2021 |
Qiu, H; Herder, M; Hecht, S; Samorì, P Ternary-Responsive Field-Effect Transistors and Multilevel Memories Based on Asymmetrically Functionalized Janus Few-Layer WSe2 Article de journal Dans: Adv. Funct. Mater., 31 (2102721), 2021. @article{Qiu2021b, title = {Ternary-Responsive Field-Effect Transistors and Multilevel Memories Based on Asymmetrically Functionalized Janus Few-Layer WSe2}, author = {H. Qiu and M. Herder and S. Hecht and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adfm.202102721}, year = {2021}, date = {2021-09-02}, journal = {Adv. Funct. Mater.}, volume = {31}, number = {2102721}, abstract = {Hybrids composed of 2D transition metal dichalcogenides with stimuli-responsive molecules are prototypical components for the development of multifunctional field-effect transistors (FETs), whose output currents can be remotely controlled by external inputs. Herein, ternary-responsive FETs based on a few-layer WSe2 are realized by decorating the two opposite surfaces of the 2D semiconductor with different stimuli-responsive molecules in an asymmetric fashion: the bottom surface is interfaced with a photochromic diarylethene film and the top surface with a ferroelectric poly(vinylidene fluoride–trifluoroethylene) layer. This novel Janus ternary device architecture shows superior functional complexity compared with normal mono-stimuli-responsive FETs. The synergy between the two molecularly induced effects enables the devices to respond orthogonally to an electric field and light irradiation, with an enhanced output current modulation efficiency of 87%. The 9 ferroelectric and 84 photo-generated states ensure 756 current levels in a single device. The over 10 cycles of cyclic endurance and more than 1000 h of retention time confirm the reliability of each state, implementing the demand for high-density non-volatile memories, as well as enriching the diversification in “More than Moore” technologies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hybrids composed of 2D transition metal dichalcogenides with stimuli-responsive molecules are prototypical components for the development of multifunctional field-effect transistors (FETs), whose output currents can be remotely controlled by external inputs. Herein, ternary-responsive FETs based on a few-layer WSe2 are realized by decorating the two opposite surfaces of the 2D semiconductor with different stimuli-responsive molecules in an asymmetric fashion: the bottom surface is interfaced with a photochromic diarylethene film and the top surface with a ferroelectric poly(vinylidene fluoride–trifluoroethylene) layer. This novel Janus ternary device architecture shows superior functional complexity compared with normal mono-stimuli-responsive FETs. The synergy between the two molecularly induced effects enables the devices to respond orthogonally to an electric field and light irradiation, with an enhanced output current modulation efficiency of 87%. The 9 ferroelectric and 84 photo-generated states ensure 756 current levels in a single device. The over 10 cycles of cyclic endurance and more than 1000 h of retention time confirm the reliability of each state, implementing the demand for high-density non-volatile memories, as well as enriching the diversification in “More than Moore” technologies. |
Gullace, S; Montes-García, V; Martín, V; Larios, D; Consolaro, Girelli V; Obelleiro, F; Calogero, G; Casalini, S; Samorì, P Universal Fabrication of Highly Efficient Plasmonic Thin-Films for Label-Free SERS Detection Article de journal Dans: Small, 17 (2100755), 2021. @article{Gullace2021, title = {Universal Fabrication of Highly Efficient Plasmonic Thin-Films for Label-Free SERS Detection}, author = {S. Gullace and V. Montes-García and V. Martín and D. Larios and V. Girelli Consolaro and F. Obelleiro and G. Calogero and S. Casalini and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/smll.202100755}, year = {2021}, date = {2021-08-19}, journal = {Small}, volume = {17}, number = {2100755}, abstract = {The development of novel, highly efficient, reliable, and robust surface enhanced Raman scattering (SERS) substrates containing a large number of hot spots with programmed size, geometry, and density is extremely interesting since it allows the sensing of numerous (bio-)chemical species. Herein, an extremely reliable, easy to fabricate, and label-free SERS sensing platform based on metal nanoparticles (NPs) thin-film is developed by the layer-by-layer growth mediated by polyelectrolytes. A systematic study of the effect of NP composition and size, as well as the number of deposition steps on the substrate's performance, is accomplished by monitoring the SERS enhancement of 1-naphtalenethiol (532 nm excitation). Distinct evidence of the key role played by the interlayer (poly(diallyldimethylammonium chloride) (PDDA) or PDDA-functionalized graphene oxide (GO@PDDA)) on the overall SERS efficiency of the plasmonic platforms is provided, revealing in the latter the formation of more uniform hot spots by regulating the interparticle distances to 5 ± 1 nm. The SERS platform efficiency is demonstrated via its high analytical enhancement factor (≈106) and the detection of a prototypical substance(tamoxifen), both in Milli-Q water and in a real matrix, viz. tap water, opening perspectives towards the use of plasmonic platforms for future high-performance sensing applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The development of novel, highly efficient, reliable, and robust surface enhanced Raman scattering (SERS) substrates containing a large number of hot spots with programmed size, geometry, and density is extremely interesting since it allows the sensing of numerous (bio-)chemical species. Herein, an extremely reliable, easy to fabricate, and label-free SERS sensing platform based on metal nanoparticles (NPs) thin-film is developed by the layer-by-layer growth mediated by polyelectrolytes. A systematic study of the effect of NP composition and size, as well as the number of deposition steps on the substrate's performance, is accomplished by monitoring the SERS enhancement of 1-naphtalenethiol (532 nm excitation). Distinct evidence of the key role played by the interlayer (poly(diallyldimethylammonium chloride) (PDDA) or PDDA-functionalized graphene oxide (GO@PDDA)) on the overall SERS efficiency of the plasmonic platforms is provided, revealing in the latter the formation of more uniform hot spots by regulating the interparticle distances to 5 ± 1 nm. The SERS platform efficiency is demonstrated via its high analytical enhancement factor (≈106) and the detection of a prototypical substance(tamoxifen), both in Milli-Q water and in a real matrix, viz. tap water, opening perspectives towards the use of plasmonic platforms for future high-performance sensing applications. |
de Oliveira, Furlan R; Montes-García, V; Ciesielski, A; Samorì, P Harnessing selectivity in chemical sensing via supramolecular interactions: from functionalization of nanomaterials to device applications Article de journal Dans: Mater. Horiz., 8 , p. 2685–2708, 2021. @article{deOliveira2021, title = {Harnessing selectivity in chemical sensing via supramolecular interactions: from functionalization of nanomaterials to device applications}, author = {R. Furlan de Oliveira and V. Montes-García and A. Ciesielski and P. Samorì}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d1mh01117k}, year = {2021}, date = {2021-08-16}, journal = {Mater. Horiz.}, volume = {8}, pages = {2685–2708}, abstract = {Chemical sensing is a strategic field of science and technology ultimately aiming at improving the quality of our lives and the sustainability of our Planet. Sensors bear a direct societal impact on well-being, which includes the quality and composition of the air we breathe, the water we drink, and the food we eat. Pristine low-dimensional materials are widely exploited as highly sensitive elements in chemical sensors, although they suffer from lack of intrinsic selectivity towards specific analytes. Here, we showcase the most recent strategies on the use of (supra)molecular interactions to harness the selectivity of suitably functionalized 0D, 1D, and 2D low-dimensional materials for chemical sensing. We discuss how the design and selection of receptors via machine learning and artificial intelligence hold a disruptive potential in chemical sensing, where selectivity is achieved by the design and high-throughput screening of large libraries of molecules exhibiting a set of affinity parameters that dictates the analyte specificity. We also discuss the importance of achieving selectivity along with other relevant characteristics in chemical sensing, such as high sensitivity, response speed, and reversibility, as milestones for true practical applications. Finally, for each distinct class of low-dimensional material, we present the most suitable functionalization strategies for their incorporation into efficient transducers for chemical sensing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Chemical sensing is a strategic field of science and technology ultimately aiming at improving the quality of our lives and the sustainability of our Planet. Sensors bear a direct societal impact on well-being, which includes the quality and composition of the air we breathe, the water we drink, and the food we eat. Pristine low-dimensional materials are widely exploited as highly sensitive elements in chemical sensors, although they suffer from lack of intrinsic selectivity towards specific analytes. Here, we showcase the most recent strategies on the use of (supra)molecular interactions to harness the selectivity of suitably functionalized 0D, 1D, and 2D low-dimensional materials for chemical sensing. We discuss how the design and selection of receptors via machine learning and artificial intelligence hold a disruptive potential in chemical sensing, where selectivity is achieved by the design and high-throughput screening of large libraries of molecules exhibiting a set of affinity parameters that dictates the analyte specificity. We also discuss the importance of achieving selectivity along with other relevant characteristics in chemical sensing, such as high sensitivity, response speed, and reversibility, as milestones for true practical applications. Finally, for each distinct class of low-dimensional material, we present the most suitable functionalization strategies for their incorporation into efficient transducers for chemical sensing. |
Wang, Y; Iglesias, D; Gali, S M; Beljonne, D; Samorì, P Light-Programmable Logic-in-Memory in 2D Semiconductors Enabled by Supramolecular Functionalization: Photoresponsive Collective Effect of Aligned Molecular Dipoles Article de journal Dans: ACS Nano, 15 , p. 13732–13741, 2021. @article{Wang2021b, title = {Light-Programmable Logic-in-Memory in 2D Semiconductors Enabled by Supramolecular Functionalization: Photoresponsive Collective Effect of Aligned Molecular Dipoles}, author = {Y. Wang and D. Iglesias and S. M. Gali and D. Beljonne and P. Samorì}, editor = {ACS Publcation}, url = {https://doi.org/10.1021/acsnano.1c05167}, year = {2021}, date = {2021-08-09}, journal = {ACS Nano}, volume = {15}, pages = {13732–13741}, abstract = {Nowadays, the unrelenting growth of the digital universe calls for radically novel strategies for data processing and storage. An extremely promising and powerful approach relies on the development of logic-in-memory (LiM) devices through the use of floating gate and ferroelectric technologies to write and erase data in a memory operating as a logic gate driven by electrical bias. In this work, we report an alternative approach to realize the logic-in-memory based on two-dimensional (2D) transition metal dichalcogenides (TMDs) where multiple memorized logic output states have been established via the interface with responsive molecular dipoles arranged in supramolecular arrays. The collective dynamic molecular dipole changes of the axial ligand coordinated onto self-assembled metal phthalocyanine nanostructures on the surface of 2D TMD enables large reversible modulation of the Fermi level of both n-type molybdenum disulfide (MoS2) and p-type tungsten diselenide (WSe2) field-effect transistors (FETs), to achieve multiple memory states by programming and erasing with ultraviolet (UV) and with visible light, respectively. As a result, logic-in-memory devices were built up with our supramolecular layer/2D TMD architecture where the output logic is encoded by the motion of the molecular dipoles. Our strategy relying on the dynamic control of the 2D electronics by harnessing the functions of molecular-dipole-induced memory in a supramolecular hybrid layer represents a versatile way to integrate the functional programmability of molecular science into the next generation nanoelectronics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nowadays, the unrelenting growth of the digital universe calls for radically novel strategies for data processing and storage. An extremely promising and powerful approach relies on the development of logic-in-memory (LiM) devices through the use of floating gate and ferroelectric technologies to write and erase data in a memory operating as a logic gate driven by electrical bias. In this work, we report an alternative approach to realize the logic-in-memory based on two-dimensional (2D) transition metal dichalcogenides (TMDs) where multiple memorized logic output states have been established via the interface with responsive molecular dipoles arranged in supramolecular arrays. The collective dynamic molecular dipole changes of the axial ligand coordinated onto self-assembled metal phthalocyanine nanostructures on the surface of 2D TMD enables large reversible modulation of the Fermi level of both n-type molybdenum disulfide (MoS2) and p-type tungsten diselenide (WSe2) field-effect transistors (FETs), to achieve multiple memory states by programming and erasing with ultraviolet (UV) and with visible light, respectively. As a result, logic-in-memory devices were built up with our supramolecular layer/2D TMD architecture where the output logic is encoded by the motion of the molecular dipoles. Our strategy relying on the dynamic control of the 2D electronics by harnessing the functions of molecular-dipole-induced memory in a supramolecular hybrid layer represents a versatile way to integrate the functional programmability of molecular science into the next generation nanoelectronics. |
Chen, Y; Wang, H; Yao, Y; Wang, Y; Ma, C; Samorì, P Synaptic Plasticity Powering Long-Afterglow Organic Light-Emitting Transistors Article de journal Dans: Adv. Mater., 33 (2103369), 2021. @article{Chen2021, title = {Synaptic Plasticity Powering Long-Afterglow Organic Light-Emitting Transistors}, author = {Y. Chen and H. Wang and Y. Yao and Y. Wang and C. Ma and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adma.202103369}, year = {2021}, date = {2021-08-08}, journal = {Adv. Mater.}, volume = {33}, number = {2103369}, abstract = {Long-lasting luminescence in optoelectronic devices is highly sought after for applications in optical data storage and display technology. While in light-emitting diodes this is achieved by exploiting long-afterglow organic materials as active components, such a strategy has never been pursued in light-emitting transistors, which are still rather unexplored and whose technological potential is yet to be demonstrated. Herein, the fabrication of long-afterglow organic light-emitting transistors (LAOLETs) is reported whose operation relies on an unprecedented strategy based on a photoinduced synaptic effect in an inorganic indium-gallium-zinc-oxide (IGZO) semiconducting channel layer, to power a persistent electroluminescence in organic light-emitting materials. Oxygen vacancies in the IGZO layer, produced by irradiation at λ = 312 nm, free electrons in excess yielding to a channel conductance increase. Due to the slow recombination kinetics of photogenerated electrons to oxygen vacancies in the channel layer, the organic material can be fueled by postsynaptic current and displays a long-lived light-emission (hundreds of seconds) after ceasing UV irradiation. As a proof-of-concept, the LAOLETs are integrated in active-matrix light-emitting arrays operating as visual UV sensors capable of long-lifetime green-light emission in the irradiated regions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Long-lasting luminescence in optoelectronic devices is highly sought after for applications in optical data storage and display technology. While in light-emitting diodes this is achieved by exploiting long-afterglow organic materials as active components, such a strategy has never been pursued in light-emitting transistors, which are still rather unexplored and whose technological potential is yet to be demonstrated. Herein, the fabrication of long-afterglow organic light-emitting transistors (LAOLETs) is reported whose operation relies on an unprecedented strategy based on a photoinduced synaptic effect in an inorganic indium-gallium-zinc-oxide (IGZO) semiconducting channel layer, to power a persistent electroluminescence in organic light-emitting materials. Oxygen vacancies in the IGZO layer, produced by irradiation at λ = 312 nm, free electrons in excess yielding to a channel conductance increase. Due to the slow recombination kinetics of photogenerated electrons to oxygen vacancies in the channel layer, the organic material can be fueled by postsynaptic current and displays a long-lived light-emission (hundreds of seconds) after ceasing UV irradiation. As a proof-of-concept, the LAOLETs are integrated in active-matrix light-emitting arrays operating as visual UV sensors capable of long-lifetime green-light emission in the irradiated regions. |
Wang, Y; Wang, H; Gali, S M; Turetta, N; Yao, Y; Wang, C; anf Beljonne, Chen Y D; Samorì, P Molecular Doping of 2D Indium Selenide for Ultrahigh Performance and Low-Power Consumption Broadband Photodetectors Article de journal Dans: Adv. Funct. Mater., 31 (2103353), 2021. @article{Wang2021b, title = {Molecular Doping of 2D Indium Selenide for Ultrahigh Performance and Low-Power Consumption Broadband Photodetectors}, author = {Y. Wang and H. Wang and S. M. Gali and N. Turetta and Y. Yao and C. Wang and Y. Chen anf D. Beljonne and P. Samorì}, editor = {Wiley Online Library }, url = {https://doi.org/10.1002/adfm.202103353}, year = {2021}, date = {2021-07-23}, journal = {Adv. Funct. Mater.}, volume = {31}, number = {2103353}, abstract = {Two-dimensional (2D) photodetecting materials have shown superior performances over traditional materials (e.g., silicon, perylenes), which demonstrate low responsivity (R) (<1 AW−1), external quantum efficiency (EQE) (<100%), and limited detection bandwidth. Recently, 2D indium selenide (InSe) emerged as high-performance active material in field-effect transistors and photodetectors, whose fabrication required expensive and complex techniques. Here, it is shown for the first time how molecular functionalization with a common surfactant molecule (didodecyldimethylammonium bromide) (DDAB) represents a powerful strategy to boost the (opto)electronic performances of InSe yielding major performance enhancements in phototransistors, Schottky junctions, and van der Waals heterostructures via a lithography-compatible fabrication route. The functionalization can controllably dope and heal vacancies in InSe, resulting in ultrahigh field-effect mobility (103 cm2 V−1 s−1) and photoresponsivity (106 A W−1), breaking the record of non-graphene-contacted 2D photodetectors. The strategy towards the molecular doping of 2D photodetecting materials is efficient, practical, up-scalable, and operable with ultra-low power input, ultimately paving the way to next-generation 2D opto-electronics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional (2D) photodetecting materials have shown superior performances over traditional materials (e.g., silicon, perylenes), which demonstrate low responsivity (R) (<1 AW−1), external quantum efficiency (EQE) (<100%), and limited detection bandwidth. Recently, 2D indium selenide (InSe) emerged as high-performance active material in field-effect transistors and photodetectors, whose fabrication required expensive and complex techniques. Here, it is shown for the first time how molecular functionalization with a common surfactant molecule (didodecyldimethylammonium bromide) (DDAB) represents a powerful strategy to boost the (opto)electronic performances of InSe yielding major performance enhancements in phototransistors, Schottky junctions, and van der Waals heterostructures via a lithography-compatible fabrication route. The functionalization can controllably dope and heal vacancies in InSe, resulting in ultrahigh field-effect mobility (103 cm2 V−1 s−1) and photoresponsivity (106 A W−1), breaking the record of non-graphene-contacted 2D photodetectors. The strategy towards the molecular doping of 2D photodetecting materials is efficient, practical, up-scalable, and operable with ultra-low power input, ultimately paving the way to next-generation 2D opto-electronics. |
Anichini, C; Czepa, W; Aliprandi, A; Consolaro, Girelli V; Ersen, O; Ciesielski, A; Samorì, P Synthesis and characterization of ultralong copper sulfide nanowires and their electrical properties Article de journal Dans: J. Mater. Chem. C, 9 , p. 12133–12140, 2021. @article{Anichini2021b, title = {Synthesis and characterization of ultralong copper sulfide nanowires and their electrical properties}, author = {C. Anichini and W. Czepa and A. Aliprandi and V. Girelli Consolaro and O. Ersen and A. Ciesielski and P. Samorì}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d1tc03004c}, year = {2021}, date = {2021-07-21}, journal = {J. Mater. Chem. C}, volume = {9}, pages = {12133–12140}, abstract = { We report the synthesis of ultralong copper sulfide nanowires (Cu2−xSNWs) through the sulphidation reaction of metallic copper nanowires (CuNWs) by thiourea under mild conditions. The multiscale characterization of Cu2−xSNWs revealed the presence of a core shell structure made up of an external covellite layer coating a roxbyite core. The Cu2−xSNWs, exhibiting lengths as high as 200 μm, can be easily dispersed in ethanol and deposited onto arbitrary substrates such as glass or plastic. The resulting films are readily conducting without the need for post-treatments and exhibit a sheet resistance of 4.1 kΩ sq−1 at 73.7% transmittance (at 550 nm), by virtue of the high aspect ratio of the Cu2−xSNWs. The multiscale electrical characterization down to the single Cu2−xSNWs revealed a low resistivity of 6.9 × 10−6 Ω m and perfect Ohmic conductivity. Interestingly, the conductivity of Cu2−xSNW films supported on polyethylene naphthalate sheets remained almost unaltered (4% decrease) after 10 000 bending cycles. In addition, Cu2−xSNWs have shown excellent chemical stability towards a strong oxidant like FeCl3 as well as in an acidic environment. Finally, Cu2−xSNWs have been employed as active materials in symmetric supercapacitors revealing good pseudocapacitive behaviour, with specific capacity as high as 324 F g−1 (at 5 mV s−1) and 70% retention of the initial capacitance after 5000 cycles (at 100 mV s−1). }, keywords = {}, pubstate = {published}, tppubtype = {article} } We report the synthesis of ultralong copper sulfide nanowires (Cu2−xSNWs) through the sulphidation reaction of metallic copper nanowires (CuNWs) by thiourea under mild conditions. The multiscale characterization of Cu2−xSNWs revealed the presence of a core shell structure made up of an external covellite layer coating a roxbyite core. The Cu2−xSNWs, exhibiting lengths as high as 200 μm, can be easily dispersed in ethanol and deposited onto arbitrary substrates such as glass or plastic. The resulting films are readily conducting without the need for post-treatments and exhibit a sheet resistance of 4.1 kΩ sq−1 at 73.7% transmittance (at 550 nm), by virtue of the high aspect ratio of the Cu2−xSNWs. The multiscale electrical characterization down to the single Cu2−xSNWs revealed a low resistivity of 6.9 × 10−6 Ω m and perfect Ohmic conductivity. Interestingly, the conductivity of Cu2−xSNW films supported on polyethylene naphthalate sheets remained almost unaltered (4% decrease) after 10 000 bending cycles. In addition, Cu2−xSNWs have shown excellent chemical stability towards a strong oxidant like FeCl3 as well as in an acidic environment. Finally, Cu2−xSNWs have been employed as active materials in symmetric supercapacitors revealing good pseudocapacitive behaviour, with specific capacity as high as 324 F g−1 (at 5 mV s−1) and 70% retention of the initial capacitance after 5000 cycles (at 100 mV s−1). |
Campitiello, M; Cremonini, A; Squillaci, M A; Pieraccini, S; Ciesielski, A; Samorì, P; Masiero, S Self-Assembly of Functionalized Lipophilic Guanosines into Cation-Free Stacked Guanine-Quartets Article de journal Dans: J. Org. Chem., 86 , p. 9970–9978, 2021. @article{Campitiello2021, title = {Self-Assembly of Functionalized Lipophilic Guanosines into Cation-Free Stacked Guanine-Quartets}, author = {M. Campitiello and A. Cremonini and M. A. Squillaci and S. Pieraccini and A. Ciesielski and P. Samorì and S. Masiero}, editor = {ACS }, url = {https://doi.org/10.1021/acs.joc.1c00502}, year = {2021}, date = {2021-07-19}, journal = {J. Org. Chem.}, volume = {86}, pages = {9970–9978}, abstract = {The hierarchical self-assembly of various lipophilic guanosines exposing either a phenyl or a ferrocenyl group in the C(8) position was investigated. In a solution, all the derivatives were found to self-assemble primarily into isolated guanine (G)-quartets. In spite of the apparent similar bulkiness of the two substituents, most of the derivatives form disordered structures in the solid state, whereas a specific 8-phenyl derivative self-assembles into an unprecedented, cation-free stacked G-quartet architecture.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The hierarchical self-assembly of various lipophilic guanosines exposing either a phenyl or a ferrocenyl group in the C(8) position was investigated. In a solution, all the derivatives were found to self-assemble primarily into isolated guanine (G)-quartets. In spite of the apparent similar bulkiness of the two substituents, most of the derivatives form disordered structures in the solid state, whereas a specific 8-phenyl derivative self-assembles into an unprecedented, cation-free stacked G-quartet architecture. |
Krystek, M; Ciesielski, A; Samorì, P Graphene‐Based Cementitious Composites: Toward Next‐Generation Construction Technologies Article de journal Dans: Adv. Funct. Mater., 31 (2101887), 2021. @article{Krystek2021b, title = {Graphene‐Based Cementitious Composites: Toward Next‐Generation Construction Technologies}, author = {M. Krystek and A. Ciesielski and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adfm.202101887}, year = {2021}, date = {2021-07-02}, journal = {Adv. Funct. Mater.}, volume = {31}, number = {2101887}, abstract = {The search for technological solutions to the ever-increasing demand for ultra-high-quality concrete with the simultaneous construction boom represents one of the greatest challenges concrete researchers are facing nowadays. In view of their unique properties, graphene and related materials, when utilized to form graphene-based cementitious composites, appear to be powerful components to give a boost to today's concrete technology. In this review, the most enlightening recent advancements in the development of fabrication protocols for obtaining the homogenous dispersion of graphene and derivatives thereof within the cement matrix are showcased. The hydration process and basic properties of graphene-based cementitious materials are also discussed. The integration of graphene-family materials to concrete technology allows new functions to be imparted to cement composites toward the construction of smart and multifunctional buildings. Therefore, a specific focus is given to the electrical and piezoresistive behavior of graphene-cement composites, and ultimately their great potential for structural health monitoring applications. The approaches proposed in this review can be also extended to other 2D materials offering the broadest arsenal of physical properties, which can therefore be integrated on-demand in future smart structures and constructions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The search for technological solutions to the ever-increasing demand for ultra-high-quality concrete with the simultaneous construction boom represents one of the greatest challenges concrete researchers are facing nowadays. In view of their unique properties, graphene and related materials, when utilized to form graphene-based cementitious composites, appear to be powerful components to give a boost to today's concrete technology. In this review, the most enlightening recent advancements in the development of fabrication protocols for obtaining the homogenous dispersion of graphene and derivatives thereof within the cement matrix are showcased. The hydration process and basic properties of graphene-based cementitious materials are also discussed. The integration of graphene-family materials to concrete technology allows new functions to be imparted to cement composites toward the construction of smart and multifunctional buildings. Therefore, a specific focus is given to the electrical and piezoresistive behavior of graphene-cement composites, and ultimately their great potential for structural health monitoring applications. The approaches proposed in this review can be also extended to other 2D materials offering the broadest arsenal of physical properties, which can therefore be integrated on-demand in future smart structures and constructions. |
Anichini, C; Samorì, P Graphene-Based Hybrid Functional Materials Article de journal Dans: Small, 17 (2100514), 2021. @article{Anichini2021, title = {Graphene-Based Hybrid Functional Materials}, author = {C. Anichini and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/smll.202100514}, year = {2021}, date = {2021-06-26}, journal = {Small}, volume = {17}, number = {2100514}, abstract = {Graphene is a 2D material combining numerous outstanding physical properties, including high flexibility and strength, extremely high thermal conductivity and electron mobility, transparency, etc., which make it a unique testbed to explore fundamental physical phenomena. Such physical properties can be further tuned by combining graphene with other nanomaterials or (macro)molecules to form hybrid functional materials, which by design can display not only the properties of the individual components but also exhibit new properties and enhanced characteristics arising from the synergic interaction of the components. The implementation of the hybrid approach to graphene also allows boosting the performances in a multitude of technological applications. This review reports the hybrids formed by graphene combined with other low-dimensional nanomaterials of diverse dimensionality (0D, 1D, and 2D) and (macro)molecules, with emphasis on the synthetic methods. The most important applications of these hybrids in the fields of sensing, water purification, energy storage, biomedical, (photo)catalysis, and opto(electronics) are also reviewed, with a special focus on the superior performances of these hybrids compared to the individual, nonhybridized components.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Graphene is a 2D material combining numerous outstanding physical properties, including high flexibility and strength, extremely high thermal conductivity and electron mobility, transparency, etc., which make it a unique testbed to explore fundamental physical phenomena. Such physical properties can be further tuned by combining graphene with other nanomaterials or (macro)molecules to form hybrid functional materials, which by design can display not only the properties of the individual components but also exhibit new properties and enhanced characteristics arising from the synergic interaction of the components. The implementation of the hybrid approach to graphene also allows boosting the performances in a multitude of technological applications. This review reports the hybrids formed by graphene combined with other low-dimensional nanomaterials of diverse dimensionality (0D, 1D, and 2D) and (macro)molecules, with emphasis on the synthetic methods. The most important applications of these hybrids in the fields of sensing, water purification, energy storage, biomedical, (photo)catalysis, and opto(electronics) are also reviewed, with a special focus on the superior performances of these hybrids compared to the individual, nonhybridized components. |
Yao, Y; Ou, Q; Wang, K; Peng, H; Fang, F; Shi, Y; Wang, Y; Asperilla, Iglesias D; Shuai, Z; and S. Lara Avila, Samorì P Supramolecular engineering of charge transfer in wide bandgap organic semiconductors with enhanced visible-to-NIR photoresponse Article de journal Dans: Nat. Commun, 12 (3667), 2021. @article{Yao2021, title = {Supramolecular engineering of charge transfer in wide bandgap organic semiconductors with enhanced visible-to-NIR photoresponse}, author = {Y. Yao and Q. Ou and K. Wang and H. Peng and F. Fang and Y. Shi and Y. Wang and D. Iglesias Asperilla and Z. Shuai and S. Lara Avila ,and P. Samorì}, editor = {Nature communication}, url = {https://www.nature.com/articles/s41467-021-23914-2}, year = {2021}, date = {2021-06-16}, journal = {Nat. Commun}, volume = {12}, number = {3667}, abstract = {Organic photodetectors displaying efficient photoelectric response in the near-infrared are typically based on narrow bandgap active materials. Unfortunately, the latter require complex molecular design to ensure sufficient light absorption in the near-infrared region. Here, we show a method combining an unconventional device architecture and ad-hoc supramolecular self-assembly to trigger the emergence of opto-electronic properties yielding to remarkably high near-infrared response using a wide bandgap material as active component. Our optimized vertical phototransistors comprising a network of supramolecular nanowires of N,N′-dioctyl-3,4,9,10-perylenedicarboximide sandwiched between a monolayer graphene bottom-contact and Au nanomesh scaffold top-electrode exhibit ultrasensitive light response to monochromatic light from visible to near-infrared range, with photoresponsivity of 2 × 105 A/W and 1 × 102 A/W, at 570 nm and 940 nm, respectively, hence outperforming devices based on narrow bandgap materials. Moreover, these devices also operate as highly sensitive photoplethysmography tool for health monitoring.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Organic photodetectors displaying efficient photoelectric response in the near-infrared are typically based on narrow bandgap active materials. Unfortunately, the latter require complex molecular design to ensure sufficient light absorption in the near-infrared region. Here, we show a method combining an unconventional device architecture and ad-hoc supramolecular self-assembly to trigger the emergence of opto-electronic properties yielding to remarkably high near-infrared response using a wide bandgap material as active component. Our optimized vertical phototransistors comprising a network of supramolecular nanowires of N,N′-dioctyl-3,4,9,10-perylenedicarboximide sandwiched between a monolayer graphene bottom-contact and Au nanomesh scaffold top-electrode exhibit ultrasensitive light response to monochromatic light from visible to near-infrared range, with photoresponsivity of 2 × 105 A/W and 1 × 102 A/W, at 570 nm and 940 nm, respectively, hence outperforming devices based on narrow bandgap materials. Moreover, these devices also operate as highly sensitive photoplethysmography tool for health monitoring. |
Cusin, L; Peng, H; Ciesielski, A; Samorì, P Chemical Conversion and Locking of the Imine Linkage: Enhancing the Functionality of Covalent Organic Frameworks Article de journal Dans: Angew. Chem. Int. Ed., 60 , p. 14236–14250, 2021. @article{Cusin2021, title = {Chemical Conversion and Locking of the Imine Linkage: Enhancing the Functionality of Covalent Organic Frameworks}, author = {L. Cusin and H. Peng and A. Ciesielski and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/anie.202016667}, year = {2021}, date = {2021-06-16}, journal = {Angew. Chem. Int. Ed.}, volume = {60}, pages = {14236–14250}, abstract = {Imine-based covalent organic frameworks (COFs) are a widely studied class of functional, crystalline, and porous nanostructures which combine a relatively facile crystallization with tuneable compositions and porosities. However, the imine linkage constitutes an intrinsic limitation due to its reduced stability in harsh chemical conditions and its unsuitability for in-plane π-conjugation in COFs. Urgent solutions are therefore required in order to exploit the full potential of these materials, thereby enabling their technological application in electronics, sensing, and energy storage devices. In this context, the advent of a new generation of linkages derived from the chemical conversion and locking of the imine bond represents a cornerstone for the synthesis of new COFs. A marked increase in the framework robustness is in fact often combined with the incorporation of novel functionalities including, for some of these reactions, an extension of the in-plane π-conjugation. This Minireview describes the most enlightening examples of one-pot reactions and post-synthetic modifications towards the chemical locking of the imine bond in COFs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Imine-based covalent organic frameworks (COFs) are a widely studied class of functional, crystalline, and porous nanostructures which combine a relatively facile crystallization with tuneable compositions and porosities. However, the imine linkage constitutes an intrinsic limitation due to its reduced stability in harsh chemical conditions and its unsuitability for in-plane π-conjugation in COFs. Urgent solutions are therefore required in order to exploit the full potential of these materials, thereby enabling their technological application in electronics, sensing, and energy storage devices. In this context, the advent of a new generation of linkages derived from the chemical conversion and locking of the imine bond represents a cornerstone for the synthesis of new COFs. A marked increase in the framework robustness is in fact often combined with the incorporation of novel functionalities including, for some of these reactions, an extension of the in-plane π-conjugation. This Minireview describes the most enlightening examples of one-pot reactions and post-synthetic modifications towards the chemical locking of the imine bond in COFs. |
Qiu, H; Ippolito, S; Galanti, A; Liu, Z; Samorì, P Asymmetric Dressing of WSe2 with (Macro)molecular Switches: Fabrication of Quaternary-Responsive Transistors Article de journal Dans: ACS Nano, 15 (10668–10677), 2021. @article{Qiu2021, title = {Asymmetric Dressing of WSe2 with (Macro)molecular Switches: Fabrication of Quaternary-Responsive Transistors}, author = {H. Qiu and S. Ippolito and A. Galanti and Z. Liu and P. Samorì}, editor = {ACS Publcation}, url = {https://doi.org/10.1021/acsnano.1c03549}, year = {2021}, date = {2021-06-07}, journal = {ACS Nano}, volume = {15}, number = {10668–10677}, abstract = {The forthcoming saturation of Moore’s law has led to a strong demand for integrating analogue functionalities within semiconductor-based devices. As a step toward this goal, we fabricate quaternary-responsive WSe2-based field-effect transistors (FETs) whose output current can be remotely and reversibly controlled by light, heat, and electric field. A photochromic silane-terminated spiropyran (SP) is chemisorbed on SiO2 forming a self-assembled monolayer (SAM) that can switch from the SP to the merocyanine (MC) form in response to UV illumination and switch back by either heat or visible illumination. Such a SAM is incorporated at the dielectric–semiconductor interface in WSe2-based FETs. Upon UV irradiation, a drastic decrease in the output current of 82% is observed and ascribed to the zwitterionic MC isomer acting as charge scattering site. To provide an additional functionality, the WSe2 top surface is coated with a ferroelectric co-polymer layer based on poly(vinylidene fluoride-co-trifluoroethylene). Because of its switchable inherent electrical polarization, it can promote either the accumulation or depletion of charge carriers in the WSe2 channel, thereby inducing a current modulation with 99% efficiency. Thanks to the efficient tuning induced by the two components and their synergistic effects, the device polarity could be modulated from n-type to p-type. Such a control over the carrier concentration and device polarity is key to develop 2D advanced electronics. Moreover, the integration strategy of multiple stimuli-responsive elements into a single FET allows us to greatly enrich its functionality, thereby promoting the development for More-than-Moore technology.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The forthcoming saturation of Moore’s law has led to a strong demand for integrating analogue functionalities within semiconductor-based devices. As a step toward this goal, we fabricate quaternary-responsive WSe2-based field-effect transistors (FETs) whose output current can be remotely and reversibly controlled by light, heat, and electric field. A photochromic silane-terminated spiropyran (SP) is chemisorbed on SiO2 forming a self-assembled monolayer (SAM) that can switch from the SP to the merocyanine (MC) form in response to UV illumination and switch back by either heat or visible illumination. Such a SAM is incorporated at the dielectric–semiconductor interface in WSe2-based FETs. Upon UV irradiation, a drastic decrease in the output current of 82% is observed and ascribed to the zwitterionic MC isomer acting as charge scattering site. To provide an additional functionality, the WSe2 top surface is coated with a ferroelectric co-polymer layer based on poly(vinylidene fluoride-co-trifluoroethylene). Because of its switchable inherent electrical polarization, it can promote either the accumulation or depletion of charge carriers in the WSe2 channel, thereby inducing a current modulation with 99% efficiency. Thanks to the efficient tuning induced by the two components and their synergistic effects, the device polarity could be modulated from n-type to p-type. Such a control over the carrier concentration and device polarity is key to develop 2D advanced electronics. Moreover, the integration strategy of multiple stimuli-responsive elements into a single FET allows us to greatly enrich its functionality, thereby promoting the development for More-than-Moore technology. |
Jiang, B; Che, Y; Chen, Y; Zhao, Y; Wang, C; Li, W; Zheng, H; Huang, X; Samorì, P; Zhang, L Wafer-Scale and Full-Coverage Two-Dimensional Molecular Monolayers Strained by Solvent Surface Tension Balance Article de journal Dans: ACS Appl. Mater. Interfaces, 13 , p. 26218–26226, 2021. @article{Jiang2021, title = {Wafer-Scale and Full-Coverage Two-Dimensional Molecular Monolayers Strained by Solvent Surface Tension Balance}, author = {B. Jiang and Y. Che and Y. Chen and Y. Zhao and C. Wang and W. Li and H. Zheng and X. Huang and P. Samorì and L. Zhang}, editor = {ACS }, url = {https://doi.org/10.1021/acsami.1c04198}, year = {2021}, date = {2021-05-31}, journal = {ACS Appl. Mater. Interfaces}, volume = {13}, pages = {26218–26226}, abstract = {Inspired by the outstanding properties discovered in two-dimensional materials, the bottom-up generation of molecular monolayers is becoming again extremely popular as a route to develop novel functional materials and devices with tailored characteristics and minimal materials consumption. However, achieving a full-coverage over a large-area still represents a grand challenge. Here we report a molecular self-assembly protocol at the water surface in which the monolayers are strained by a novel solvent surface tension balance (SSTB) instead of a physical film balance as in the conventional Langmuir–Blodgett (LB) method. The obtained molecular monolayers can be transferred onto any arbitrary substrate including rigid inorganic oxides and metals, as well as flexible polymeric dielectrics. As a proof-of-concept, their application as ideal modification layers of a dielectric support for high-performance organic field-effect transistors (OFETs) has been demonstrated. The field-effect mobilities of both p- and n-type semiconductors displayed dramatic improvements of 1–3 orders of magnitude on SSTB-derived molecular monolayer, reaching values as high as 6.16 cm2 V–1 s–1 and 0.68 cm2 V–1 s–1 for pentacene and PTCDI-C8, respectively. This methodology for the fabrication of wafer-scale and defect-free molecular monolayers holds potential toward the emergence of a new generation of high-performance electronics based on two-dimensional materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Inspired by the outstanding properties discovered in two-dimensional materials, the bottom-up generation of molecular monolayers is becoming again extremely popular as a route to develop novel functional materials and devices with tailored characteristics and minimal materials consumption. However, achieving a full-coverage over a large-area still represents a grand challenge. Here we report a molecular self-assembly protocol at the water surface in which the monolayers are strained by a novel solvent surface tension balance (SSTB) instead of a physical film balance as in the conventional Langmuir–Blodgett (LB) method. The obtained molecular monolayers can be transferred onto any arbitrary substrate including rigid inorganic oxides and metals, as well as flexible polymeric dielectrics. As a proof-of-concept, their application as ideal modification layers of a dielectric support for high-performance organic field-effect transistors (OFETs) has been demonstrated. The field-effect mobilities of both p- and n-type semiconductors displayed dramatic improvements of 1–3 orders of magnitude on SSTB-derived molecular monolayer, reaching values as high as 6.16 cm2 V–1 s–1 and 0.68 cm2 V–1 s–1 for pentacene and PTCDI-C8, respectively. This methodology for the fabrication of wafer-scale and defect-free molecular monolayers holds potential toward the emergence of a new generation of high-performance electronics based on two-dimensional materials. |
Turetta, N; Sedona, F; Liscio, A; Sambi, M; Samorì, P Au(111) Surface Contamination in Ambient Conditions: Unravelling the Dynamics of the Work Function in Air Article de journal Dans: Adv. Mater. Interfaces, 8 (2100068), 2021. @article{Sedona2021, title = {Au(111) Surface Contamination in Ambient Conditions: Unravelling the Dynamics of the Work Function in Air}, author = {N. Turetta And F. Sedona and A. Liscio and M. Sambi and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/admi.202100068}, year = {2021}, date = {2021-05-21}, journal = {Adv. Mater. Interfaces}, volume = {8}, number = {2100068}, abstract = {Gold is an inert noble metal displaying superior chemical stability that renders it a suitable component for the manufacturing of electrodes for various types of devices. Despite being widely employed, the variation of gold surface properties occurring upon the material's exposure to ambient conditions have been often disregarded. While it is well-known that the contamination of a metallic surface can have a dramatic impact on its properties, the process of contamination itself is poorly understood. Changes of the work function by fractions of an electron-volt are commonly observed in gold surfaces that are processed at ambient laboratory conditions, but an exhaustive comprehension and control of this phenomenon are still lacking. Here, a multiscale characterization of Au(111) surfaces aiming to unravel the surface dynamics underlying the air contamination is presented. The visualization of the adventitious carbon contamination on Au(111) surface by atomic force microscopy is key to rationalize the mechanisms of surface reorganization ruling the change of Au work function between 5.25 and 4.75 eV by solely changing the storage conditions. Such a huge variation must be taken into account when optimizing the Au surface for both controlling its fundamental surface and interfacial physical processes, as well as its functional applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Gold is an inert noble metal displaying superior chemical stability that renders it a suitable component for the manufacturing of electrodes for various types of devices. Despite being widely employed, the variation of gold surface properties occurring upon the material's exposure to ambient conditions have been often disregarded. While it is well-known that the contamination of a metallic surface can have a dramatic impact on its properties, the process of contamination itself is poorly understood. Changes of the work function by fractions of an electron-volt are commonly observed in gold surfaces that are processed at ambient laboratory conditions, but an exhaustive comprehension and control of this phenomenon are still lacking. Here, a multiscale characterization of Au(111) surfaces aiming to unravel the surface dynamics underlying the air contamination is presented. The visualization of the adventitious carbon contamination on Au(111) surface by atomic force microscopy is key to rationalize the mechanisms of surface reorganization ruling the change of Au work function between 5.25 and 4.75 eV by solely changing the storage conditions. Such a huge variation must be taken into account when optimizing the Au surface for both controlling its fundamental surface and interfacial physical processes, as well as its functional applications. |
Pakulski, D; Gorczyński, A; Marcinkowski, D; Czepa, W; Chudziak, T; Witomska, S; Nishina, Y; Patroniak, V; Ciesielski, A; Samorì, Paolo High-sorption terpyridine–graphene oxide hybrid for the efficient removal of heavy metal ions from wastewater Article de journal Dans: Nanoscale, 13 , p. 10490–10499, 2021. @article{Pakulski2021, title = {High-sorption terpyridine–graphene oxide hybrid for the efficient removal of heavy metal ions from wastewater}, author = {D. Pakulski and A. Gorczyński and D. Marcinkowski and W. Czepa and T. Chudziak and S. Witomska and Y. Nishina and V. Patroniak and A. Ciesielski and Paolo Samorì}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d1nr02255e}, year = {2021}, date = {2021-05-12}, journal = {Nanoscale}, volume = {13}, pages = {10490–10499}, abstract = {Pollution of wastewater with heavy metal-ions represents one of the most severe environmental problems associated with societal development. To overcome this issue, the design of new, highly efficient systems capable of removing such toxic species, hence to purify water, is of paramount importance for public health and environmental protection. In this work, novel sorption hybrid materials were developed to enable high-performance adsorption of heavy metal ions. Towards this end, graphene oxide (GO) exhibiting various C/O ratios has been functionalized with ad hoc receptors, i.e. terpyridine ligands. The maximum adsorption capacity of highly oxidized/terpyridine hybrids towards Ni(II), Zn(II) and Co(II) was achieved at pH = 6 and 25 °C reaching values of 462, 421 and 336 mg g−1, respectively, being the highest reported in the literature for pristine GO and GO-based sorbents. Moreover, the uptake experiments showed that heavy metal ion adsorption on GO–Tpy and GOh–Tpy is strongly dependent on pH in the range from 2 to 10, as a result of the modulation of interactions at the supramolecular level. Moreover, the ionic strength was found to be independent of heavy metal ion adsorption on GO–Tpy and GOh–Tpy. Under ambient conditions, adsorption capacity values increase with the degree of oxidation of GO because dipolar oxygen units can both interact with heavy-metal ions via dipole–dipole and/or ionic interactions and enable bonding of more covalently anchored terpyridine units. Both adsorption isotherms and kinetics studies revealed that the uptake of the heavy metal ions occurs at a monolayer coverage, mostly controlled by the strong surface complexation with the oxygen of GO and nitrogen-containing groups of terpyridine. Furthermore, selectivity of the hybrid was confirmed by selective sorption of the above heavy metal ions from mixtures involving alkali (Na(I), K(I)) and alkaline Earth (Mg(II), Ca(II)) metal ions due to the chelating properties of the terpyridine subunits, as demonstrated with municipal drinking (tap) water samples. Our findings provide unambiguous evidence for the potential of chemical tailoring of GO-based materials with N-heterocyclic ligands as sorbent materials for highly efficient wastewater purification.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pollution of wastewater with heavy metal-ions represents one of the most severe environmental problems associated with societal development. To overcome this issue, the design of new, highly efficient systems capable of removing such toxic species, hence to purify water, is of paramount importance for public health and environmental protection. In this work, novel sorption hybrid materials were developed to enable high-performance adsorption of heavy metal ions. Towards this end, graphene oxide (GO) exhibiting various C/O ratios has been functionalized with ad hoc receptors, i.e. terpyridine ligands. The maximum adsorption capacity of highly oxidized/terpyridine hybrids towards Ni(II), Zn(II) and Co(II) was achieved at pH = 6 and 25 °C reaching values of 462, 421 and 336 mg g−1, respectively, being the highest reported in the literature for pristine GO and GO-based sorbents. Moreover, the uptake experiments showed that heavy metal ion adsorption on GO–Tpy and GOh–Tpy is strongly dependent on pH in the range from 2 to 10, as a result of the modulation of interactions at the supramolecular level. Moreover, the ionic strength was found to be independent of heavy metal ion adsorption on GO–Tpy and GOh–Tpy. Under ambient conditions, adsorption capacity values increase with the degree of oxidation of GO because dipolar oxygen units can both interact with heavy-metal ions via dipole–dipole and/or ionic interactions and enable bonding of more covalently anchored terpyridine units. Both adsorption isotherms and kinetics studies revealed that the uptake of the heavy metal ions occurs at a monolayer coverage, mostly controlled by the strong surface complexation with the oxygen of GO and nitrogen-containing groups of terpyridine. Furthermore, selectivity of the hybrid was confirmed by selective sorption of the above heavy metal ions from mixtures involving alkali (Na(I), K(I)) and alkaline Earth (Mg(II), Ca(II)) metal ions due to the chelating properties of the terpyridine subunits, as demonstrated with municipal drinking (tap) water samples. Our findings provide unambiguous evidence for the potential of chemical tailoring of GO-based materials with N-heterocyclic ligands as sorbent materials for highly efficient wastewater purification. |
Krystek, M; Pakulski, D; Górski, M; Szojda, L; Ciesielski, A; Samorì, P Electrochemically Exfoliated Graphene for High-Durability Cement Composites Article de journal Dans: ACS Appl. Mater. Interfaces, 13 , p. 23000–23010, 2021. @article{Krystek2021, title = {Electrochemically Exfoliated Graphene for High-Durability Cement Composites}, author = {M. Krystek and D. Pakulski and M. Górski and L. Szojda and A. Ciesielski and P. Samorì}, editor = {ACS Publcation}, url = {https://doi.org/10.1021/acsami.1c04451}, year = {2021}, date = {2021-05-04}, journal = {ACS Appl. Mater. Interfaces}, volume = {13}, pages = {23000–23010}, abstract = {The development of radically new types of corrosion-resistant cement composites is nowadays compulsory in view of the continuous increase of concrete consumption combined with the intrinsically defective nature of concrete. Among various additives being employed in the concrete technology, carbon nanomaterials have emerged as extremely powerful components capable of remarkably enhancing nano- and microstructures as well as properties of cement-based composites. In this study, we demonstrate that cement mortar incorporating electrochemically exfoliated graphene (EEG) exhibits significantly improved fluid transport properties. The addition of 0.05 wt % of EEG to ordinary Portland cement mortar results in the reduction of initial and secondary sorptivity values by 21 and 25%, respectively. This leads to the outstanding resistance of EEG–cement composites to highly corrosive environments, namely, chloride and sulfate solutions. These observations, combined with the previously reported remarkable enhancement of the tensile strength of EEG–cement mortars, represent a major step toward the development of highly durable graphene-based cement composites.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The development of radically new types of corrosion-resistant cement composites is nowadays compulsory in view of the continuous increase of concrete consumption combined with the intrinsically defective nature of concrete. Among various additives being employed in the concrete technology, carbon nanomaterials have emerged as extremely powerful components capable of remarkably enhancing nano- and microstructures as well as properties of cement-based composites. In this study, we demonstrate that cement mortar incorporating electrochemically exfoliated graphene (EEG) exhibits significantly improved fluid transport properties. The addition of 0.05 wt % of EEG to ordinary Portland cement mortar results in the reduction of initial and secondary sorptivity values by 21 and 25%, respectively. This leads to the outstanding resistance of EEG–cement composites to highly corrosive environments, namely, chloride and sulfate solutions. These observations, combined with the previously reported remarkable enhancement of the tensile strength of EEG–cement mortars, represent a major step toward the development of highly durable graphene-based cement composites. |
Wang, H; Wang, Y; Ni, Z; Turetta, N; Gali, S M; Peng, H; Yao, Y; Chen, Y; Janica, I; Beljonne, D; Hu, W; Ciesielski, A; Samorì, P 2D MXene–Molecular Hybrid Additive for High-Performance Ambipolar Polymer Field-Effect Transistors and Logic Gates Article de journal Dans: Adv. Mater., 33 , p. 2008215, 2021. @article{Wang2021, title = {2D MXene–Molecular Hybrid Additive for High-Performance Ambipolar Polymer Field-Effect Transistors and Logic Gates}, author = {H. Wang and Y. Wang and Z. Ni and N. Turetta and S. M. Gali and H. Peng and Y. Yao and Y. Chen and I. Janica and D. Beljonne and W. Hu and A. Ciesielski and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adma.202008215}, year = {2021}, date = {2021-04-12}, journal = {Adv. Mater.}, volume = {33}, pages = {2008215}, abstract = {MXenes are highly conductive layered materials that are attracting a great interest for high-performance opto-electronics, photonics, and energy applications.. Their non-covalent functionalization with ad hoc molecules enables the production of stable inks of 2D flakes to be processed in thin-films. Here, the formation of stable dispersions via the intercalation of Ti3C2Tx with didecyldimethyl ammonium bromide (DDAB) yielding Ti3C2Tx–DDAB, is demonstrated. Such functionalization modulates the properties of Ti3C2Tx, as evidenced by a 0.47 eV decrease of the work function. It is also shown that DDAB is a powerful n-dopant capable of enhancing electron mobility in conjugated polymers and 2D materials. When Ti3C2Tx–DDAB is blended with poly(diketopyrrolopyrrole-co-selenophene) [(PDPP–Se)], a simultaneous increase by 170% and 152% of the hole and electron field-effect mobilities, respectively, is observed, compared to the neat conjugated polymer, with values reaching 2.0 cm2 V−1 s−1. By exploiting the balanced ambipolar transport of the Ti3C2Tx–DDAB/PDPP–Se hybrid, complementary metal–oxide–semiconductor (CMOS) logic gates are fabricated that display well-centered trip points and good noise margin (64.6% for inverter). The results demonstrate that intercalant engineering represents an efficient strategy to tune the electronic properties of Ti3C2Tx yielding functionalized MXenes for polymer transistors with unprecedented performances and functions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } MXenes are highly conductive layered materials that are attracting a great interest for high-performance opto-electronics, photonics, and energy applications.. Their non-covalent functionalization with ad hoc molecules enables the production of stable inks of 2D flakes to be processed in thin-films. Here, the formation of stable dispersions via the intercalation of Ti3C2Tx with didecyldimethyl ammonium bromide (DDAB) yielding Ti3C2Tx–DDAB, is demonstrated. Such functionalization modulates the properties of Ti3C2Tx, as evidenced by a 0.47 eV decrease of the work function. It is also shown that DDAB is a powerful n-dopant capable of enhancing electron mobility in conjugated polymers and 2D materials. When Ti3C2Tx–DDAB is blended with poly(diketopyrrolopyrrole-co-selenophene) [(PDPP–Se)], a simultaneous increase by 170% and 152% of the hole and electron field-effect mobilities, respectively, is observed, compared to the neat conjugated polymer, with values reaching 2.0 cm2 V−1 s−1. By exploiting the balanced ambipolar transport of the Ti3C2Tx–DDAB/PDPP–Se hybrid, complementary metal–oxide–semiconductor (CMOS) logic gates are fabricated that display well-centered trip points and good noise margin (64.6% for inverter). The results demonstrate that intercalant engineering represents an efficient strategy to tune the electronic properties of Ti3C2Tx yielding functionalized MXenes for polymer transistors with unprecedented performances and functions. |
Carroli, M; Dixon, A G; Herder, M; Pavlica, E; Hecht, S; Bratina, G; Orgiu, E; Samorì, P Multiresponsive Nonvolatile Memories Based on Optically Switchable Ferroelectric Organic Field‐Effect Transistors Article de journal Dans: Adv. Mater., 33 (2007965), 2021. @article{Carroli2021, title = {Multiresponsive Nonvolatile Memories Based on Optically Switchable Ferroelectric Organic Field‐Effect Transistors}, author = {M. Carroli and A. G. Dixon and M. Herder and E. Pavlica and S. Hecht and G. Bratina and E. Orgiu and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adma.202007965}, year = {2021}, date = {2021-04-07}, journal = {Adv. Mater.}, volume = {33}, number = {2007965}, abstract = {Organic transistors are key elements for flexible, wearable, and biocompatible logic applications. Multiresponsivity is highly sought‐after in organic electronics to enable sophisticated operations and functions. Such a challenge can be pursued by integrating more components in a single device, each one responding to a specific external stimulus. Here, the first multiresponsive organic device based on a photochromic–ferroelectric organic field‐effect transistor, which is capable of operating as nonvolatile memory with 11 bit memory storage capacity in a single device, is reported. The memory elements can be written and erased independently by means of light or an electric field, with accurate control over the readout signal, excellent repeatability, fast response, and high retention time. Such a proof of concept paves the way toward enhanced functional complexity in optoelectronics via the interfacing of multiple components in a single device, in a fully integrated low‐cost technology compatible with flexible substrates.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Organic transistors are key elements for flexible, wearable, and biocompatible logic applications. Multiresponsivity is highly sought‐after in organic electronics to enable sophisticated operations and functions. Such a challenge can be pursued by integrating more components in a single device, each one responding to a specific external stimulus. Here, the first multiresponsive organic device based on a photochromic–ferroelectric organic field‐effect transistor, which is capable of operating as nonvolatile memory with 11 bit memory storage capacity in a single device, is reported. The memory elements can be written and erased independently by means of light or an electric field, with accurate control over the readout signal, excellent repeatability, fast response, and high retention time. Such a proof of concept paves the way toward enhanced functional complexity in optoelectronics via the interfacing of multiple components in a single device, in a fully integrated low‐cost technology compatible with flexible substrates. |
Stoeckel, M ‐A; Olivier, Y; Gobbi, M; Dudenko, D; Lemaur, V; Zbiri, M; Guilbert, A A Y; D'Avino, G; Liscio, F; Migliori, A; Ortolani, L; Demitri, N; Jin, X; Jeong, Y ‐G; Liscio, A; Nardia, M ‐V; Pasquali, L; Razzari, L; Beljonne, D; Samorì, P; Orgiu, E Analysis of External and Internal Disorder to Understand Band‐Like Transport in n‐Type Organic Semiconductors Article de journal Dans: Adv. Mater., 33 (2007870), 2021. @article{Stoeckel2021, title = {Analysis of External and Internal Disorder to Understand Band‐Like Transport in n‐Type Organic Semiconductors}, author = {M.‐A. Stoeckel and Y. Olivier and M. Gobbi and D. Dudenko and V. Lemaur and M. Zbiri and A. A. Y. Guilbert and G. D'Avino and F. Liscio and A. Migliori and L. Ortolani and N. Demitri and X. Jin and Y.‐G. Jeong and A. Liscio and M.‐V. Nardia and L. Pasquali and L. Razzari and D. Beljonne and P. Samorì and E. Orgiu}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adma.202007870}, year = {2021}, date = {2021-04-01}, journal = {Adv. Mater.}, volume = {33}, number = {2007870}, abstract = {Charge transport in organic semiconductors is notoriously extremely sensitive to the presence of disorder, both internal and external (i.e., related to interactions with the dielectric layer), especially for n‐type materials. Internal dynamic disorder stems from large thermal fluctuations both in intermolecular transfer integrals and (molecular) site energies in weakly interacting van der Waals solids and sources transient localization of the charge carriers. The molecular vibrations that drive transient localization typically operate at low‐frequency ( pubstate = {published}, tppubtype = {article} } Charge transport in organic semiconductors is notoriously extremely sensitive to the presence of disorder, both internal and external (i.e., related to interactions with the dielectric layer), especially for n‐type materials. Internal dynamic disorder stems from large thermal fluctuations both in intermolecular transfer integrals and (molecular) site energies in weakly interacting van der Waals solids and sources transient localization of the charge carriers. The molecular vibrations that drive transient localization typically operate at low‐frequency (<a‐few‐hundred cm−1), which makes it difficult to assess them experimentally. Hitherto, this has prevented the identification of clear molecular design rules to control and reduce dynamic disorder. In addition, the disorder can also be external, being controlled by the gate insulator dielectric properties. Here a comprehensive study of charge transport in two closely related n‐type molecular organic semiconductors using a combination of temperature‐dependent inelastic neutron scattering and photoelectron spectroscopy corroborated by electrical measurements, theory, and simulations is reported. Unambiguous evidence that ad hoc molecular design enables the electron charge carriers to be freed from both internal and external disorder to ultimately reach band‐like electron transport is provided. |
Reina, G; Iglesias, D; Samorì, P; Bianco, A Graphene: A Disruptive Opportunity for COVID‐19 and Future Pandemics? Article de journal Dans: Adv. Mater., 33 (2007847), 2021. @article{Reina2021, title = {Graphene: A Disruptive Opportunity for COVID‐19 and Future Pandemics?}, author = {G. Reina and D. Iglesias and P. Samorì and A. Bianco}, editor = {Wiley Online Library }, url = {https://doi.org/10.1002/adma.202007847}, year = {2021}, date = {2021-03-11}, journal = {Adv. Mater.}, volume = {33}, number = {2007847}, abstract = {The graphene revolution, which has taken place during the last 15 years, has represented a paradigm shift for science. The extraordinary properties possessed by this unique material have paved the road to a number of applications in materials science, optoelectronics, energy, and sensing. Graphene‐related materials (GRMs) are now produced in large scale and have found niche applications also in the biomedical technologies, defining new standards for drug delivery and biosensing. Such advances position GRMs as novel tools to fight against the current COVID‐19 and future pandemics. In this regard, GRMs can play a major role in sensing, as an active component in antiviral surfaces or in virucidal formulations. Herein, the most promising strategies reported in the literature on the use of GRM‐based materials against the COVID‐19 pandemic and other types of viruses are showcased, with a strong focus on the impact of functionalization, deposition techniques, and integration into devices and surface coatings.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The graphene revolution, which has taken place during the last 15 years, has represented a paradigm shift for science. The extraordinary properties possessed by this unique material have paved the road to a number of applications in materials science, optoelectronics, energy, and sensing. Graphene‐related materials (GRMs) are now produced in large scale and have found niche applications also in the biomedical technologies, defining new standards for drug delivery and biosensing. Such advances position GRMs as novel tools to fight against the current COVID‐19 and future pandemics. In this regard, GRMs can play a major role in sensing, as an active component in antiviral surfaces or in virucidal formulations. Herein, the most promising strategies reported in the literature on the use of GRM‐based materials against the COVID‐19 pandemic and other types of viruses are showcased, with a strong focus on the impact of functionalization, deposition techniques, and integration into devices and surface coatings. |
Montes-García, V; de Oliveira, Furlan R; andA. Berezin, Wang Y; Fanjul-Bolado, P; García, González M B; Hermans, T M; Bonifazi, D; Casalini, S; Samorì, P Harnessing Selectivity and Sensitivity in Ion Sensing via Supramolecular Recognition: A 3D Hybrid Gold Nanoparticle Network Chemiresistor Article de journal Dans: Adv. Funct. Mater., 31 (2008554), 2021. @article{Montes-García2021b, title = {Harnessing Selectivity and Sensitivity in Ion Sensing via Supramolecular Recognition: A 3D Hybrid Gold Nanoparticle Network Chemiresistor}, author = {V. Montes-García and R. Furlan de Oliveira and Y. Wang andA. Berezin and P. Fanjul-Bolado and M. B. González García and T. M. Hermans and D. Bonifazi and S. Casalini and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adfm.202008554}, year = {2021}, date = {2021-03-03}, journal = {Adv. Funct. Mater.}, volume = {31}, number = {2008554}, abstract = {The monitoring of K+ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K+ sensors are unable to meet the requirements for the development of point‐of‐care (POC) sensors. To tackle this grand‐challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad‐hoc supramolecular receptors for K+, namely dithiomethylene dibenzo‐18‐crown‐6 ether is reported here. A multi‐technique characterization allows optimizing a new protocol for fabricating high‐performing CRs for real‐time monitoring of K+ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10–3 to 10–6 m concentration range; ii) high selectivity to K+ in presence of interfering cations (Na+, Ca2+, and Mg2+); iii) high shelf‐life stability (>45 days); iv) reversibility of K+ binding and release; v) successful device integration into microfluidic systems for real‐time monitoring; vi) fast response and recovery times (<18 s), and v) K+ detection in artificial saliva. All these characteristics make the supramolecular CRs a potential tool for future applications as POC devices, especially for health monitoring where the determination of K+ in saliva is pivotal for the early diagnosis of diseases.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The monitoring of K+ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K+ sensors are unable to meet the requirements for the development of point‐of‐care (POC) sensors. To tackle this grand‐challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad‐hoc supramolecular receptors for K+, namely dithiomethylene dibenzo‐18‐crown‐6 ether is reported here. A multi‐technique characterization allows optimizing a new protocol for fabricating high‐performing CRs for real‐time monitoring of K+ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10–3 to 10–6 m concentration range; ii) high selectivity to K+ in presence of interfering cations (Na+, Ca2+, and Mg2+); iii) high shelf‐life stability (>45 days); iv) reversibility of K+ binding and release; v) successful device integration into microfluidic systems for real‐time monitoring; vi) fast response and recovery times (<18 s), and v) K+ detection in artificial saliva. All these characteristics make the supramolecular CRs a potential tool for future applications as POC devices, especially for health monitoring where the determination of K+ in saliva is pivotal for the early diagnosis of diseases. |
Ippolito, S; Kelly, A G; de Oliveira, Furlan R; Stoeckel, M -A; Iglesias, D; A. Roy, Downing C; Z. Bian, Lombardi L; Samad, Y A; V. Nicolosi, Ferrari A C; Coleman, J N; Samorì, P Covalently interconnected transition metal dichalcogenide networks via defect engineering for high-performance electronic devices Article de journal Dans: Nat. Nanotechnol., 16 , p. 592–598, 2021. @article{Ippolito2021b, title = {Covalently interconnected transition metal dichalcogenide networks via defect engineering for high-performance electronic devices}, author = {S. Ippolito and A. G. Kelly and R. Furlan de Oliveira and M.-A. Stoeckel and D. Iglesias and A. Roy, C. Downing and Z. Bian, L. Lombardi and Y. A. Samad and V. Nicolosi, A. C. Ferrari and J. N. Coleman and P. Samorì}, editor = {Nature Nanotechnology }, url = {https://doi.org/10.1038/s41565-021-00857-9}, year = {2021}, date = {2021-02-25}, journal = {Nat. Nanotechnol.}, volume = {16}, pages = {592–598}, abstract = {Solution-processed semiconducting transition metal dichalcogenides are at the centre of an ever-increasing research effort in printed (opto)electronics. However, device performance is limited by structural defects resulting from the exfoliation process and poor inter-flake electronic connectivity. Here, we report a new molecular strategy to boost the electrical performance of transition metal dichalcogenide-based devices via the use of dithiolated conjugated molecules, to simultaneously heal sulfur vacancies in solution-processed transition metal disulfides and covalently bridge adjacent flakes, thereby promoting percolation pathways for the charge transport. We achieve a reproducible increase by one order of magnitude in field-effect mobility (µFE), current ratio (ION/IOFF) and switching time (τS) for liquid-gated transistors, reaching 10−2 cm2 V−1 s−1, 104 and 18 ms, respectively. Our functionalization strategy is a universal route to simultaneously enhance the electronic connectivity in transition metal disulfide networks and tailor on demand their physicochemical properties according to the envisioned applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Solution-processed semiconducting transition metal dichalcogenides are at the centre of an ever-increasing research effort in printed (opto)electronics. However, device performance is limited by structural defects resulting from the exfoliation process and poor inter-flake electronic connectivity. Here, we report a new molecular strategy to boost the electrical performance of transition metal dichalcogenide-based devices via the use of dithiolated conjugated molecules, to simultaneously heal sulfur vacancies in solution-processed transition metal disulfides and covalently bridge adjacent flakes, thereby promoting percolation pathways for the charge transport. We achieve a reproducible increase by one order of magnitude in field-effect mobility (µFE), current ratio (ION/IOFF) and switching time (τS) for liquid-gated transistors, reaching 10−2 cm2 V−1 s−1, 104 and 18 ms, respectively. Our functionalization strategy is a universal route to simultaneously enhance the electronic connectivity in transition metal disulfide networks and tailor on demand their physicochemical properties according to the envisioned applications. |
Huang, C -B; Yao, Y; Montes-García, V; Stoeckel, M -A; Holst, Von M; Ciesielski, A; Samorì, P Highly Sensitive Strain Sensors Based on Molecules–Gold Nanoparticles Networks for High‐Resolution Human Pulse Analysis Article de journal Dans: Small, 17 (2007593), 2021. @article{Huang2021, title = {Highly Sensitive Strain Sensors Based on Molecules–Gold Nanoparticles Networks for High‐Resolution Human Pulse Analysis}, author = {C.-B. Huang and Y. Yao and V. Montes-García and M.-A. Stoeckel and M. Von Holst and A. Ciesielski and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/smll.202007593}, year = {2021}, date = {2021-02-24}, journal = {Small}, volume = {17}, number = {2007593}, abstract = {High‐performance flexible strain sensors are key components for the next generation of wearable health monitoring devices. Here, the authors have fabricated a novel strain sensor based on gold nanoparticles (AuNPs) interconnected by flexible and responsive molecular linkers. The combination of conductive AuNPs (25 nm in diameter) with tetra(ethylene glycol) dithiol (SH‐TEG‐SH) linkers yields a covalent 3D network which can be directly deposited onto prepatterned flexible supports exposing interdigitated Au electrodes. The electrically insulating nature of the linkers effectively defines the tunneling modulated charge transfer through the AuNPs network. When compressive/tensile strain is applied, the molecular linkers adopt a compressed/stretched conformation thus decreasing/increasing the interparticle distance, ultimately yielding an exponential increase/decrease of the tunneling current when voltage is applied. The strain sensor displays state‐of‐the‐art performances including a highly sensitive response to both tensile and compressive strain, as quantified by a high gauge factor (GF≈126) combined with other superior sensing properties like high flexibility, short response time (16.1 ms), and good robustness (>2000 cycles). Finally, the applicability of the device for health monitoring is demonstrated: high‐resolution artery pulse waves are acquired by placing the strain sensor onto the skin allowing the extraction of important physical parameters for human‐health assessment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } High‐performance flexible strain sensors are key components for the next generation of wearable health monitoring devices. Here, the authors have fabricated a novel strain sensor based on gold nanoparticles (AuNPs) interconnected by flexible and responsive molecular linkers. The combination of conductive AuNPs (25 nm in diameter) with tetra(ethylene glycol) dithiol (SH‐TEG‐SH) linkers yields a covalent 3D network which can be directly deposited onto prepatterned flexible supports exposing interdigitated Au electrodes. The electrically insulating nature of the linkers effectively defines the tunneling modulated charge transfer through the AuNPs network. When compressive/tensile strain is applied, the molecular linkers adopt a compressed/stretched conformation thus decreasing/increasing the interparticle distance, ultimately yielding an exponential increase/decrease of the tunneling current when voltage is applied. The strain sensor displays state‐of‐the‐art performances including a highly sensitive response to both tensile and compressive strain, as quantified by a high gauge factor (GF≈126) combined with other superior sensing properties like high flexibility, short response time (16.1 ms), and good robustness (>2000 cycles). Finally, the applicability of the device for health monitoring is demonstrated: high‐resolution artery pulse waves are acquired by placing the strain sensor onto the skin allowing the extraction of important physical parameters for human‐health assessment. |
Richard, J; Joseph, J; Wang, C; Ciesielski, A; Weiss, J; Samorì, P; Mamane, V; Wytko, J A Functionalized 4,4′-Bipyridines: Synthesis and 2D Organization on Highly Oriented Pyrolytic Graphite Article de journal Dans: J. Org. Chem., 86 , p. 3356−3366, 2021. @article{Richard2021, title = {Functionalized 4,4′-Bipyridines: Synthesis and 2D Organization on Highly Oriented Pyrolytic Graphite}, author = {J. Richard and J. Joseph and C. Wang and A. Ciesielski and J. Weiss and P. Samorì and V. Mamane and J. A. Wytko}, editor = {ACS Publcation}, url = {https://doi.org/10.1021/acs.joc.0c02708}, year = {2021}, date = {2021-02-04}, journal = {J. Org. Chem.}, volume = {86}, pages = {3356−3366}, abstract = {Commercial 4,4′-bipyridine is a popular scaffold that is primarily employed as a linker in 3D self-assembled architectures such as metallo-organic frameworks or as a connector in 2D networks. The introduction of alkyl substituents on the bipyridine skeleton is instrumental when 4,4′-bipyridines are used as linkers to form 2D self-assembled patterns on surfaces. Here, several synthetic strategies to access 4,4′-bipyridines functionalized at various positions are described. These easily scalable reactions have been used to introduce a range of alkyl substituents at positions 2 and 2′ or 3 and 3′ and at positions 2,2′ and 6,6′ in the case of tetra-functionalization. Scanning tunneling microscopy studies of molecular monolayers physisorbed at the graphite–solution interface revealed different supramolecular patterns whose motifs are primarily dictated by the nature and position of the alkyl chains.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Commercial 4,4′-bipyridine is a popular scaffold that is primarily employed as a linker in 3D self-assembled architectures such as metallo-organic frameworks or as a connector in 2D networks. The introduction of alkyl substituents on the bipyridine skeleton is instrumental when 4,4′-bipyridines are used as linkers to form 2D self-assembled patterns on surfaces. Here, several synthetic strategies to access 4,4′-bipyridines functionalized at various positions are described. These easily scalable reactions have been used to introduce a range of alkyl substituents at positions 2 and 2′ or 3 and 3′ and at positions 2,2′ and 6,6′ in the case of tetra-functionalization. Scanning tunneling microscopy studies of molecular monolayers physisorbed at the graphite–solution interface revealed different supramolecular patterns whose motifs are primarily dictated by the nature and position of the alkyl chains. |
Montes-García, V; Squillaci, M A; Diez-Castellnou, M; Ong, Q K; Stellacci, F; Samorì, P Chemical sensing with Au and Ag nanoparticles Article de journal Dans: Chem. Soc. Rev., 50 , p. 1269–1304, 2021. @article{Montes-García2021, title = {Chemical sensing with Au and Ag nanoparticles}, author = {V. Montes-García and M. A. Squillaci and M. Diez-Castellnou and Q. K. Ong and F. Stellacci and P. Samorì}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d0cs01112f}, year = {2021}, date = {2021-01-21}, journal = {Chem. Soc. Rev.}, volume = {50}, pages = {1269–1304}, abstract = {Noble metal nanoparticles (NPs) are ideal scaffolds for the fabrication of sensing devices because of their high surface-to-volume ratio combined with their unique optical and electrical properties which are extremely sensitive to changes in the environment. Such characteristics guarantee high sensitivity in sensing processes. Metal NPs can be decorated with ad hoc molecular building blocks which can act as receptors of specific analytes. By pursuing this strategy, and by taking full advantage of the specificity of supramolecular recognition events, highly selective sensing devices can be fabricated. Besides, noble metal NPs can also be a pivotal element for the fabrication of chemical nose/tongue sensors to target complex mixtures of analytes. This review highlights the most enlightening strategies developed during the last decade, towards the fabrication of chemical sensors with either optical or electrical readout combining high sensitivity and selectivity, along with fast response and full reversibility, with special attention to approaches that enable efficient environmental and health monitoring.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Noble metal nanoparticles (NPs) are ideal scaffolds for the fabrication of sensing devices because of their high surface-to-volume ratio combined with their unique optical and electrical properties which are extremely sensitive to changes in the environment. Such characteristics guarantee high sensitivity in sensing processes. Metal NPs can be decorated with ad hoc molecular building blocks which can act as receptors of specific analytes. By pursuing this strategy, and by taking full advantage of the specificity of supramolecular recognition events, highly selective sensing devices can be fabricated. Besides, noble metal NPs can also be a pivotal element for the fabrication of chemical nose/tongue sensors to target complex mixtures of analytes. This review highlights the most enlightening strategies developed during the last decade, towards the fabrication of chemical sensors with either optical or electrical readout combining high sensitivity and selectivity, along with fast response and full reversibility, with special attention to approaches that enable efficient environmental and health monitoring. |
Kovtun, A; Candini, A; Vianelli, A; Boschi, A; Dell’Elce, S; Gobbi, M; Kim, K H; and S. Lara Avila, Samorì P; Affronte, M; Liscio, A; Palermo, V Multiscale Charge Transport in van der Waals Thin Films: Reduced Graphene Oxide as a Case Study Article de journal Dans: ACS Nano, (15), p. 2654–2667, 2021. @article{Kovtun2021, title = {Multiscale Charge Transport in van der Waals Thin Films: Reduced Graphene Oxide as a Case Study}, author = {A. Kovtun and A. Candini and A. Vianelli and A. Boschi and S. Dell’Elce and M. Gobbi and K. H. Kim and S. Lara Avila ,and P. Samorì and M. Affronte and A. Liscio and V. Palermo}, editor = {ACS Publcation}, url = {https://doi.org/10.1021/acsnano.0c07771}, year = {2021}, date = {2021-01-19}, journal = {ACS Nano}, number = {15}, pages = {2654–2667}, abstract = {Large area van der Waals (vdW) thin films are assembled materials consisting of a network of randomly stacked nanosheets. The multiscale structure and the two-dimensional (2D) nature of the building block mean that interfaces naturally play a crucial role in the charge transport of such thin films. While single or few stacked nanosheets (i.e., vdW heterostructures) have been the subject of intensive works, little is known about how charges travel through multilayered, more disordered networks. Here, we report a comprehensive study of a prototypical system given by networks of randomly stacked reduced graphene oxide 2D nanosheets, whose chemical and geometrical properties can be controlled independently, permitting to explore percolated networks ranging from a single nanosheet to some billions with room-temperature resistivity spanning from 10–5 to 10–1 Ω·m. We systematically observe a clear transition between two different regimes at a critical temperature T*: Efros–Shklovskii variable-range hopping (ES-VRH) below T* and power law behavior above. First, we demonstrate that the two regimes are strongly correlated with each other, both depending on the charge localization length ξ, calculated by the ES-VRH model, which corresponds to the characteristic size of overlapping sp2 domains belonging to different nanosheets. Thus, we propose a microscopic model describing the charge transport as a geometrical phase transition, given by the metal–insulator transition associated with the percolation of quasi-one-dimensional nanofillers with length ξ, showing that the charge transport behavior of the networks is valid for all geometries and defects of the nanosheets, ultimately suggesting a generalized description on vdW and disordered thin films.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Large area van der Waals (vdW) thin films are assembled materials consisting of a network of randomly stacked nanosheets. The multiscale structure and the two-dimensional (2D) nature of the building block mean that interfaces naturally play a crucial role in the charge transport of such thin films. While single or few stacked nanosheets (i.e., vdW heterostructures) have been the subject of intensive works, little is known about how charges travel through multilayered, more disordered networks. Here, we report a comprehensive study of a prototypical system given by networks of randomly stacked reduced graphene oxide 2D nanosheets, whose chemical and geometrical properties can be controlled independently, permitting to explore percolated networks ranging from a single nanosheet to some billions with room-temperature resistivity spanning from 10–5 to 10–1 Ω·m. We systematically observe a clear transition between two different regimes at a critical temperature T*: Efros–Shklovskii variable-range hopping (ES-VRH) below T* and power law behavior above. First, we demonstrate that the two regimes are strongly correlated with each other, both depending on the charge localization length ξ, calculated by the ES-VRH model, which corresponds to the characteristic size of overlapping sp2 domains belonging to different nanosheets. Thus, we propose a microscopic model describing the charge transport as a geometrical phase transition, given by the metal–insulator transition associated with the percolation of quasi-one-dimensional nanofillers with length ξ, showing that the charge transport behavior of the networks is valid for all geometries and defects of the nanosheets, ultimately suggesting a generalized description on vdW and disordered thin films. |
Lucas, S; Kammerer, J; Pfannmöller, M; Schröder, R R; He, Y; Li, N; Brabec, C J; Leydecker, T; Samorì, P; Marszalek, T; Pisula, W; Mena-Osteritz, E; Bäuerle, P Molecular Donor–Acceptor Dyads for Efficient Single‐Material Organic Solar Cells Article de journal Dans: Sol. RRL, 5 (1), 2021. @article{Lucas2021, title = {Molecular Donor–Acceptor Dyads for Efficient Single‐Material Organic Solar Cells}, author = {S. Lucas and J. Kammerer and M. Pfannmöller and R. R. Schröder and Y. He and N. Li and C. J. Brabec and T. Leydecker and P. Samorì and T. Marszalek and W. Pisula and E. Mena-Osteritz and P. Bäuerle}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/solr.202000653}, year = {2021}, date = {2021-01-07}, journal = {Sol. RRL}, volume = {5}, number = {1}, abstract = {Single‐material organic solar cells (SMOSCs) promise several advantages with respect to prospective applications in printed large‐area solar foils. Only one photoactive material has to be processed and the impressive thermal and photochemical long‐term stability of the devices is achieved. Herein, a novel structural design of oligomeric donor–acceptor (D–A) dyads 1–3 is established, in which an oligothiophene donor and fullerene acceptor are covalently linked by a flexible spacer of variable length. Favorable optoelectronic, charge transport, and self‐organization properties of the D–A dyads are the basis for reaching power conversion efficiencies up to 4.26% in SMOSCs. The dependence of photovoltaic and charge transport parameters in these ambipolar semiconductors on the specific molecular structure is investigated before and after post‐treatment by solvent vapor annealing. The inner nanomorphology of the photoactive films of the dyads is analyzed with transmission electron microscopy (TEM) and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS). Combined theoretical calculations result in a lamellar supramolecular order of the dyads with a D–A phase separation smaller than 2 nm. The molecular design and the precise distance between donor and acceptor moieties ensure the fundamental physical processes operative in organic solar cells and provide stabilization of D–A interfaces. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Single‐material organic solar cells (SMOSCs) promise several advantages with respect to prospective applications in printed large‐area solar foils. Only one photoactive material has to be processed and the impressive thermal and photochemical long‐term stability of the devices is achieved. Herein, a novel structural design of oligomeric donor–acceptor (D–A) dyads 1–3 is established, in which an oligothiophene donor and fullerene acceptor are covalently linked by a flexible spacer of variable length. Favorable optoelectronic, charge transport, and self‐organization properties of the D–A dyads are the basis for reaching power conversion efficiencies up to 4.26% in SMOSCs. The dependence of photovoltaic and charge transport parameters in these ambipolar semiconductors on the specific molecular structure is investigated before and after post‐treatment by solvent vapor annealing. The inner nanomorphology of the photoactive films of the dyads is analyzed with transmission electron microscopy (TEM) and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS). Combined theoretical calculations result in a lamellar supramolecular order of the dyads with a D–A phase separation smaller than 2 nm. The molecular design and the precise distance between donor and acceptor moieties ensure the fundamental physical processes operative in organic solar cells and provide stabilization of D–A interfaces. |
Yakhlifi, El S; Alfieri, M -L; Arntz, Y; Eredia, M; Ciesielski, A; Samorì, P; d’Ischia, M; Ball, V Oxidant-dependent antioxidant activity of polydopamine films: The chemistry-morphology interplay Article de journal Dans: Colloids Surf. A, 614 (126134), 2021. @article{Yakhlifi2021, title = {Oxidant-dependent antioxidant activity of polydopamine films: The chemistry-morphology interplay}, author = {S. El Yakhlifi and M.-L. Alfieri and Y. Arntz and M. Eredia and A. Ciesielski and P. Samorì and M. d’Ischia and V. Ball}, editor = {Science Direct}, url = {https://doi.org/10.1016/j.colsurfa.2021.126134}, year = {2021}, date = {2021-01-01}, journal = {Colloids Surf. A}, volume = {614}, number = {126134}, abstract = {Polydopamine (PDA) films allow to functionalize almost all materials with a conformal and chemically active coating. These coatings can react with reducible metallic cations and with all kinds of molecules carrying nucleophilic groups. Recently, our team extended PDA chemistry to a vast repertoire of oxidants and to acidic conditions. However, the influence of changes in the method of PDA deposition on the properties of the obtained coatings, in particular the antioxidant properties, have not been sufficiently explored. It is anticipated that the antioxidant properties should depend on the film preparation method. A combination of experimental techniques, atomic force microscopy, cyclic voltammetry and X ray photoelectron spectroscopy are used to relate the antioxidant properties of PDA films to their structural features and to their chemical composition. It is demonstrated that the antioxidant properties of PDA films are not only dependent on the type of the employed oxidant – which can be expected to affect a variable density of oxidizable groups on the surface of PDA - but also on the oxidant film morphology and roughness.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Polydopamine (PDA) films allow to functionalize almost all materials with a conformal and chemically active coating. These coatings can react with reducible metallic cations and with all kinds of molecules carrying nucleophilic groups. Recently, our team extended PDA chemistry to a vast repertoire of oxidants and to acidic conditions. However, the influence of changes in the method of PDA deposition on the properties of the obtained coatings, in particular the antioxidant properties, have not been sufficiently explored. It is anticipated that the antioxidant properties should depend on the film preparation method. A combination of experimental techniques, atomic force microscopy, cyclic voltammetry and X ray photoelectron spectroscopy are used to relate the antioxidant properties of PDA films to their structural features and to their chemical composition. It is demonstrated that the antioxidant properties of PDA films are not only dependent on the type of the employed oxidant – which can be expected to affect a variable density of oxidizable groups on the surface of PDA - but also on the oxidant film morphology and roughness. |
2020 |
Samorì, P; andV. Palermo, Feng X Introduction to ‘Chemistry of 2D materials: graphene and beyond' Article de journal Dans: Nanoscale, 12 , p. 24309–24310, 2020. @article{Samorì2020, title = {Introduction to ‘Chemistry of 2D materials: graphene and beyond'}, author = {P. Samorì and X. Feng andV. Palermo}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d0nr90263b}, year = {2020}, date = {2020-12-10}, journal = {Nanoscale}, volume = {12}, pages = {24309–24310}, abstract = {A graphical abstract is available for this content}, keywords = {}, pubstate = {published}, tppubtype = {article} } A graphical abstract is available for this content |
Janica, I; Iglesias, D; Ippolito, S; Ciesielski, A; Samorì, P Effect of temperature and exfoliation time on the properties of chemically exfoliated MoS2 nanosheets Article de journal Dans: Chem. Commun., 56 , p. 15573–15576, 2020. @article{Janica2020, title = {Effect of temperature and exfoliation time on the properties of chemically exfoliated MoS2 nanosheets}, author = {I. Janica and D. Iglesias and S. Ippolito and A. Ciesielski and P. Samorì}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d0cc06792j}, year = {2020}, date = {2020-11-20}, journal = {Chem. Commun.}, volume = {56}, pages = {15573–15576}, abstract = {A systematic investigation of the experimental conditions for the chemical exfoliation of MoS2 using n-butyllithium as intercalating agent has been carried out to unravel the effect of reaction time and temperature for maximizing the percentage of monolayer thick-flakes and achieve a control over the content of metallic 1T vs. semiconductive 2H phases, thereby tuning the electrical properties of ultrathin MoS2 few-layer thick films.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A systematic investigation of the experimental conditions for the chemical exfoliation of MoS2 using n-butyllithium as intercalating agent has been carried out to unravel the effect of reaction time and temperature for maximizing the percentage of monolayer thick-flakes and achieve a control over the content of metallic 1T vs. semiconductive 2H phases, thereby tuning the electrical properties of ultrathin MoS2 few-layer thick films. |
Yao, Y; Chen, Y; Wang, H; Samorì, P Organic photodetectors based on supramolecular nanostructures Article de journal Dans: SmartMat, 1 (1), 2020. @article{Yao2020, title = {Organic photodetectors based on supramolecular nanostructures}, author = {Y. Yao and Y. Chen and H. Wang and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/smm2.1009}, year = {2020}, date = {2020-11-08}, journal = {SmartMat}, volume = {1}, number = {1}, abstract = {Self‐assembly of semiconducting (macro)molecules enables the development of materials with tailored‐made properties which could be used as active components for optoelectronics applications. Supramolecular nanostructures combine the merits of soft matter and crystalline materials: They are flexible yet highly crystalline, and they can be processed with low‐cost solution methods. Photodetectors are devices capable to convert a light input into an electrical signal. To achieve high photoresponse, the photogenerated charge carriers should be transported efficiently through the self‐assembled nanostructures to reach the electrodes; this can be guaranteed via optimal π–electron overlapping between adjacent conjugated molecules. Moreover, because of the high surface‐to‐bulk ratio, supramolecular nanostructures are prone to enhance exciton dissociation. These qualities make supramolecular nanostructures perfect platforms for photoelectric conversion. This review highlights the most enlightening recent strategies developed for the fabrication of high‐performance photodetectors based on supramolecular nanostructures. We introduce the key figure‐of‐merit parameters and working mechanisms of organic photodetectors based on single components and p–n heterojunctions. In particular, we describe new methods to devise unprecedented planar and vertical devices to ultimately realize highly integrated and flexible photodetectors. The incorporation of ordered mesoscopic supramolecular nanostructures into macroscopic optoelectronic devices will offer great promise for the next generation of multifunctional and multiresponsive devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Self‐assembly of semiconducting (macro)molecules enables the development of materials with tailored‐made properties which could be used as active components for optoelectronics applications. Supramolecular nanostructures combine the merits of soft matter and crystalline materials: They are flexible yet highly crystalline, and they can be processed with low‐cost solution methods. Photodetectors are devices capable to convert a light input into an electrical signal. To achieve high photoresponse, the photogenerated charge carriers should be transported efficiently through the self‐assembled nanostructures to reach the electrodes; this can be guaranteed via optimal π–electron overlapping between adjacent conjugated molecules. Moreover, because of the high surface‐to‐bulk ratio, supramolecular nanostructures are prone to enhance exciton dissociation. These qualities make supramolecular nanostructures perfect platforms for photoelectric conversion. This review highlights the most enlightening recent strategies developed for the fabrication of high‐performance photodetectors based on supramolecular nanostructures. We introduce the key figure‐of‐merit parameters and working mechanisms of organic photodetectors based on single components and p–n heterojunctions. In particular, we describe new methods to devise unprecedented planar and vertical devices to ultimately realize highly integrated and flexible photodetectors. The incorporation of ordered mesoscopic supramolecular nanostructures into macroscopic optoelectronic devices will offer great promise for the next generation of multifunctional and multiresponsive devices. |
Peng, H; Raya, J; Richard, F; Baaziz, W; Ersen, O; Ciesielski, A; Samorì, P Synthesis of Robust MOFs@COFs Porous Hybrid Materials via an Aza‐Diels–Alder Reaction: Towards High‐Performance Supercapacitor Materials Article de journal Dans: Angew. Chem. Int. Ed, 59 , p. 19602–19609, 2020. @article{Peng2020, title = {Synthesis of Robust MOFs@COFs Porous Hybrid Materials via an Aza‐Diels–Alder Reaction: Towards High‐Performance Supercapacitor Materials}, author = {H. Peng and J. Raya and F. Richard and W. Baaziz and O. Ersen and A. Ciesielski and P. Samorì}, editor = {Wiley Online Library }, url = {https://doi.org/10.1002/anie.202008408}, year = {2020}, date = {2020-10-26}, journal = {Angew. Chem. Int. Ed}, volume = {59}, pages = {19602–19609}, abstract = {Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have attracted enormous attention in recent years. Recently, MOF@COF are emerging as hybrid architectures combining the unique features of the individual components to enable the generation of materials displaying novel physicochemical properties. Herein we report an unprecedented use of aza‐Diels–Alder cycloaddition reaction as post‐synthetic modification of MOF@COF‐LZU1, to generate aza‐MOFs@COFs hybrid porous materials with extended π‐delocalization. A a proof‐of‐concept, the obtained aza‐MOFs@COFs is used as electrode in supercapacitors displaying specific capacitance of 20.35 μF cm−2 and high volumetric energy density of 1.16 F cm−3. Our approach of post‐synthetic modification of MOFs@COFs hybrids implement rational design for the synthesis of functional porous materials and expands the plethora of promising application of MOFs@COFs hybrid porous materials in energy storage applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have attracted enormous attention in recent years. Recently, MOF@COF are emerging as hybrid architectures combining the unique features of the individual components to enable the generation of materials displaying novel physicochemical properties. Herein we report an unprecedented use of aza‐Diels–Alder cycloaddition reaction as post‐synthetic modification of MOF@COF‐LZU1, to generate aza‐MOFs@COFs hybrid porous materials with extended π‐delocalization. A a proof‐of‐concept, the obtained aza‐MOFs@COFs is used as electrode in supercapacitors displaying specific capacitance of 20.35 μF cm−2 and high volumetric energy density of 1.16 F cm−3. Our approach of post‐synthetic modification of MOFs@COFs hybrids implement rational design for the synthesis of functional porous materials and expands the plethora of promising application of MOFs@COFs hybrid porous materials in energy storage applications. |
Gobbi, M; Galanti, A; Stoeckel, M -A; Zyska, B; Bonacchi, S; Hecht, S; Samorì, P Graphene transistors for real-time monitoring molecular self-assembly dynamics Article de journal Dans: Nat. Commun, 11 (4731), 2020. @article{Gobbi2020, title = {Graphene transistors for real-time monitoring molecular self-assembly dynamics}, author = {M. Gobbi and A. Galanti and M.-A. Stoeckel and B. Zyska and S. Bonacchi and S. Hecht and P. Samorì}, editor = {Nature}, url = {https://www.nature.com/articles/s41467-020-18604-4}, year = {2020}, date = {2020-09-18}, journal = {Nat. Commun}, volume = {11}, number = {4731}, abstract = {Mastering the dynamics of molecular assembly on surfaces enables the engineering of predictable structural motifs to bestow programmable properties upon target substrates. Yet, monitoring self-assembly in real time on technologically relevant interfaces between a substrate and a solution is challenging, due to experimental complexity of disentangling interfacial from bulk phenomena. Here, we show that graphene devices can be used as highly sensitive detectors to read out the dynamics of molecular self-assembly at the solid/liquid interface in-situ. Irradiation of a photochromic molecule is used to trigger the formation of a metastable self-assembled adlayer on graphene and the dynamics of this process are monitored by tracking the current in the device over time. In perspective, the electrical readout in graphene devices is a diagnostic and highly sensitive means to resolve molecular ensemble dynamics occurring down to the nanosecond time scale, thereby providing a practical and powerful tool to investigate molecular self-organization in 2D. Introduction Molecular self-assembly on surfaces generates highly ordered 2D structures1,2,3, which are capable to impart desired functions to a substrate4,5. As the imparted functions depend on the arrangement on the molecular scale, scanning probe microscopy techniques have been widely employed to map in the direct space the architectural motifs obtained through self-assembly6,7,8,9,10,11,12. The latter, which is ruled by a complex interplay between intramolecular, intermolecular, and interfacial interactions13 is not completely understood14,15. Unraveling the dynamics of self-assembly16 could provide higher control over key parameters governing the mechanism of molecular self-organization in 2D, thereby permitting to further engineer molecular functionalization7,17. Scanning tunneling microscopy (STM) imaging enabled to monitor with sub-nanometer spatial resolution the kinetics of nucleation and rearrangements taking place in supramolecular adlayers at solid/liquid interfaces18,19,20,21, including light-responsive assemblies composed of photochromic molecules22,23,24,25,26. However, the information provided by STM is confined at a length scale of a few tens of square nanometers, thus not suitable to describe population dynamics of self-assembly on macroscopic distances, which involves billions of molecules. Moreover, the highest temporal resolution of STM is limited by the ability to record a few tens of frames per second16,27, yielding a temporal resolution of 10–100 ms, or slower (1–10 s) when it comes to visualizing molecular assemblies16. For this reason, the use of a solely electrical read out to track the ensemble dynamics of molecular self-assembly would be a highly desirable tool to attain ultrafast response and insight into the phenomena governing self-organization in 2D. While electronic devices were employed to monitor in real time single-molecule reactions28 and DNA hybridization29, the dynamics of a complex ensemble process such as the on-surface self-assembly has not been read out by means of an electronic device. Here, we demonstrate that graphene field-effect devices represent a powerful tool to monitor electrically in an easy and controllable way the complex dynamics of on-surface self-assembly of photochromic molecules. As a proof of principle, we employ a molecule that upon irradiation generates a metastable isomer capable of forming a supramolecular assembly at the graphene/solution interface, thereby introducing a light-controlled field effect on graphene analogous to that of an external gate terminal. Therefore, by measuring the temporal evolution of the electrical current flowing through graphene, we are capable to track the dynamics of formation and desorption of the metastable self-assembled monolayer. Importantly, we demonstrate that the ultrahigh surface sensitivity of graphene permits to disentangle the dynamics of self-assembly at the solid–liquid interface from those of ensemble processes taking place simultaneously in the supernatant solution, such as photoisomerization and thermal relaxation. Results Optical characterization of photoisomerization in solution For this study, we employed the spiropyran (SP) derivative shown in Fig. 1a. The octadecyl side chain promotes self-assembly on graphene by forming crystalline lamellae5. Irradiation with ultraviolet (UV) light at 365 nm triggers the conversion to the ring-open zwitterionic merocyanine (MC) isomer, which is metastable and thermally reverts back to the ring-closed SP isomer30. The photoisomerization is accompanied by a drastic change in the physical properties of the molecule, with the MC isomer being characterized by a stronger molecular dipole moment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Mastering the dynamics of molecular assembly on surfaces enables the engineering of predictable structural motifs to bestow programmable properties upon target substrates. Yet, monitoring self-assembly in real time on technologically relevant interfaces between a substrate and a solution is challenging, due to experimental complexity of disentangling interfacial from bulk phenomena. Here, we show that graphene devices can be used as highly sensitive detectors to read out the dynamics of molecular self-assembly at the solid/liquid interface in-situ. Irradiation of a photochromic molecule is used to trigger the formation of a metastable self-assembled adlayer on graphene and the dynamics of this process are monitored by tracking the current in the device over time. In perspective, the electrical readout in graphene devices is a diagnostic and highly sensitive means to resolve molecular ensemble dynamics occurring down to the nanosecond time scale, thereby providing a practical and powerful tool to investigate molecular self-organization in 2D. Introduction Molecular self-assembly on surfaces generates highly ordered 2D structures1,2,3, which are capable to impart desired functions to a substrate4,5. As the imparted functions depend on the arrangement on the molecular scale, scanning probe microscopy techniques have been widely employed to map in the direct space the architectural motifs obtained through self-assembly6,7,8,9,10,11,12. The latter, which is ruled by a complex interplay between intramolecular, intermolecular, and interfacial interactions13 is not completely understood14,15. Unraveling the dynamics of self-assembly16 could provide higher control over key parameters governing the mechanism of molecular self-organization in 2D, thereby permitting to further engineer molecular functionalization7,17. Scanning tunneling microscopy (STM) imaging enabled to monitor with sub-nanometer spatial resolution the kinetics of nucleation and rearrangements taking place in supramolecular adlayers at solid/liquid interfaces18,19,20,21, including light-responsive assemblies composed of photochromic molecules22,23,24,25,26. However, the information provided by STM is confined at a length scale of a few tens of square nanometers, thus not suitable to describe population dynamics of self-assembly on macroscopic distances, which involves billions of molecules. Moreover, the highest temporal resolution of STM is limited by the ability to record a few tens of frames per second16,27, yielding a temporal resolution of 10–100 ms, or slower (1–10 s) when it comes to visualizing molecular assemblies16. For this reason, the use of a solely electrical read out to track the ensemble dynamics of molecular self-assembly would be a highly desirable tool to attain ultrafast response and insight into the phenomena governing self-organization in 2D. While electronic devices were employed to monitor in real time single-molecule reactions28 and DNA hybridization29, the dynamics of a complex ensemble process such as the on-surface self-assembly has not been read out by means of an electronic device. Here, we demonstrate that graphene field-effect devices represent a powerful tool to monitor electrically in an easy and controllable way the complex dynamics of on-surface self-assembly of photochromic molecules. As a proof of principle, we employ a molecule that upon irradiation generates a metastable isomer capable of forming a supramolecular assembly at the graphene/solution interface, thereby introducing a light-controlled field effect on graphene analogous to that of an external gate terminal. Therefore, by measuring the temporal evolution of the electrical current flowing through graphene, we are capable to track the dynamics of formation and desorption of the metastable self-assembled monolayer. Importantly, we demonstrate that the ultrahigh surface sensitivity of graphene permits to disentangle the dynamics of self-assembly at the solid–liquid interface from those of ensemble processes taking place simultaneously in the supernatant solution, such as photoisomerization and thermal relaxation. Results Optical characterization of photoisomerization in solution For this study, we employed the spiropyran (SP) derivative shown in Fig. 1a. The octadecyl side chain promotes self-assembly on graphene by forming crystalline lamellae5. Irradiation with ultraviolet (UV) light at 365 nm triggers the conversion to the ring-open zwitterionic merocyanine (MC) isomer, which is metastable and thermally reverts back to the ring-closed SP isomer30. The photoisomerization is accompanied by a drastic change in the physical properties of the molecule, with the MC isomer being characterized by a stronger molecular dipole moment. |
Zhao, Y; Gali, S M; Wang, C; Pershin, A; Slassi, A; Beljonne, D; Samorì, P Molecular Functionalization of Chemically Active Defects in WSe2 for Enhanced Opto‐Electronics Article de journal Dans: Adv. Funct. Mater., 30 (2005045), 2020. @article{Zhao2020b, title = {Molecular Functionalization of Chemically Active Defects in WSe2 for Enhanced Opto‐Electronics}, author = {Y. Zhao and S. M. Gali and C. Wang and A. Pershin and A. Slassi and D. Beljonne and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adfm.202005045}, year = {2020}, date = {2020-09-06}, journal = {Adv. Funct. Mater.}, volume = {30}, number = {2005045}, abstract = {Structural defects are known to worsen electrical and optical properties of 2D materials. Transition metal dichalcogenides (TMDs) are prone to chalcogen vacancies and molecular functionalization of these vacancies offers a powerful strategy to engineer the crystal structure by healing such defects. This molecular approach can effectively improve physical properties of 2D materials and optimize the performance of 2D electronic devices. While this strategy has been successfully exploited to heal vacancies in sulfides, its viability on selenides based TMDs has not yet been proven. Here, by using thiophenol molecules to functionalize monolayer WSe2 surface containing Se vacancies, it is demonstrated that the defect healing via molecular approach not only improves the performance of WSe2 transistors (> tenfold increase in the current density, the electron mobility, and the Ion/Ioff ratio), but also enhances the photoluminescence properties of monolayer WSe2 flakes (threefold increase of photoluminescence intensity at room temperature). Theoretical calculations elucidate the mechanism of molecular passivation, which originates from the strong interaction between thiol functional group at Se vacancy sites and neighboring tungsten atoms. These results demonstrate that the molecular approach represents a powerful strategy to engineer WSe2 transistors and optimize their optical properties, paving the way toward high‐performance 2D (opto)electronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Structural defects are known to worsen electrical and optical properties of 2D materials. Transition metal dichalcogenides (TMDs) are prone to chalcogen vacancies and molecular functionalization of these vacancies offers a powerful strategy to engineer the crystal structure by healing such defects. This molecular approach can effectively improve physical properties of 2D materials and optimize the performance of 2D electronic devices. While this strategy has been successfully exploited to heal vacancies in sulfides, its viability on selenides based TMDs has not yet been proven. Here, by using thiophenol molecules to functionalize monolayer WSe2 surface containing Se vacancies, it is demonstrated that the defect healing via molecular approach not only improves the performance of WSe2 transistors (> tenfold increase in the current density, the electron mobility, and the Ion/Ioff ratio), but also enhances the photoluminescence properties of monolayer WSe2 flakes (threefold increase of photoluminescence intensity at room temperature). Theoretical calculations elucidate the mechanism of molecular passivation, which originates from the strong interaction between thiol functional group at Se vacancy sites and neighboring tungsten atoms. These results demonstrate that the molecular approach represents a powerful strategy to engineer WSe2 transistors and optimize their optical properties, paving the way toward high‐performance 2D (opto)electronic devices. |
Anichini, C; Aliprandi, A; Gali, S M; Liscio, F; Morandi, V; Minoia, A; Beljonne, D; Ciesielski, A; Samorì, P Ultrafast and Highly Sensitive Chemically Functionalized Graphene Oxide-Based Humidity Sensors: Harnessing Device Performances via the Supramolecular Approach Article de journal Dans: ACS Appl. Mater. Interfaces, 12 , p. 44017–44025, 2020. @article{Anichini2020, title = {Ultrafast and Highly Sensitive Chemically Functionalized Graphene Oxide-Based Humidity Sensors: Harnessing Device Performances via the Supramolecular Approach}, author = {C. Anichini and A. Aliprandi and S. M. Gali and F. Liscio and V. Morandi and A. Minoia and D. Beljonne and A. Ciesielski and P. Samorì}, editor = {ACS Publcation}, url = {https://doi.org/10.1021/acsami.0c11236}, year = {2020}, date = {2020-09-03}, journal = {ACS Appl. Mater. Interfaces}, volume = {12}, pages = {44017–44025}, abstract = {Humidity sensors have been gaining increasing attention because of their relevance for well-being. To meet the ever-growing demand for new cost-efficient materials with superior performances, graphene oxide (GO)-based relative humidity sensors have emerged recently as low-cost and highly sensitive devices. However, current GO-based sensors suffer from important drawbacks including slow response and recovery, as well as poor stability. Interestingly, reduced GO (rGO) exhibits higher stability, yet accompanied by a lower sensitivity to humidity due to its hydrophobic nature. With the aim of improving the sensing performances of rGO, here we report on a novel generation of humidity sensors based on a simple chemical modification of rGO with hydrophilic moieties, i.e., triethylene glycol chains. Such a hybrid material exhibits an outstandingly improved sensing performance compared to pristine rGO such as high sensitivity (31% increase in electrical resistance when humidity is shifted from 2 to 97%), an ultrafast response (25 ms) and recovery in the subsecond timescale, low hysteresis (1.1%), excellent repeatability and stability, as well as high selectivity toward moisture. Such highest-key-performance indicators demonstrate the full potential of two-dimensional (2D) materials when decorated with suitably designed supramolecular receptors to develop the next generation of chemical sensors of any analyte of interest.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Humidity sensors have been gaining increasing attention because of their relevance for well-being. To meet the ever-growing demand for new cost-efficient materials with superior performances, graphene oxide (GO)-based relative humidity sensors have emerged recently as low-cost and highly sensitive devices. However, current GO-based sensors suffer from important drawbacks including slow response and recovery, as well as poor stability. Interestingly, reduced GO (rGO) exhibits higher stability, yet accompanied by a lower sensitivity to humidity due to its hydrophobic nature. With the aim of improving the sensing performances of rGO, here we report on a novel generation of humidity sensors based on a simple chemical modification of rGO with hydrophilic moieties, i.e., triethylene glycol chains. Such a hybrid material exhibits an outstandingly improved sensing performance compared to pristine rGO such as high sensitivity (31% increase in electrical resistance when humidity is shifted from 2 to 97%), an ultrafast response (25 ms) and recovery in the subsecond timescale, low hysteresis (1.1%), excellent repeatability and stability, as well as high selectivity toward moisture. Such highest-key-performance indicators demonstrate the full potential of two-dimensional (2D) materials when decorated with suitably designed supramolecular receptors to develop the next generation of chemical sensors of any analyte of interest. |
Czepa, W; Witomska, S; Ciesielski, A; Samorì, P Reduced graphene oxide–silsesquioxane hybrid as a novel supercapacitor electrode Article de journal Dans: Nanoscale, 12 , p. 18733–18741, 2020. @article{Czepa2020b, title = {Reduced graphene oxide–silsesquioxane hybrid as a novel supercapacitor electrode}, author = {W. Czepa and S. Witomska and A. Ciesielski and P. Samorì}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d0nr05226d}, year = {2020}, date = {2020-08-12}, journal = {Nanoscale}, volume = {12}, pages = {18733–18741}, abstract = {Supercapacitor energy storage devices recently garnered considerable attention due to their cost-effectiveness, eco-friendly nature, high power density, moderate energy density, and long-term cycling stability. Such figures of merit render supercapacitors unique energy sources to power portable electronic devices. Among various energy storage materials, graphene-related materials have established themselves as ideal electrodes for the development of elite supercapacitors because of their excellent electrical conductivity, high surface area, outstanding mechanical properties combined with the possibility to tailor various physical and chemical properties via chemical functionalization. Increasing the surface area is a powerful strategy to improve the performance of supercapacitors. Here, modified polyhedral oligosilsesquioxane (POSS) is used to improve the electrochemical performance of reduced graphene oxide (rGO) through the enhancement of porosity and the extension of interlayer space between the sheets allowing efficient electrolyte transport. rGO–POSS hybrids exhibited a high specific capacitance of 174 F g−1, power density reaching 2.25 W cm−3, and high energy density of 41.4 mW h cm−3 endowed by the introduction of POSS spacers. Moreover, these electrode materials display excellent durability reaching >98% retention after 5000 cycles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Supercapacitor energy storage devices recently garnered considerable attention due to their cost-effectiveness, eco-friendly nature, high power density, moderate energy density, and long-term cycling stability. Such figures of merit render supercapacitors unique energy sources to power portable electronic devices. Among various energy storage materials, graphene-related materials have established themselves as ideal electrodes for the development of elite supercapacitors because of their excellent electrical conductivity, high surface area, outstanding mechanical properties combined with the possibility to tailor various physical and chemical properties via chemical functionalization. Increasing the surface area is a powerful strategy to improve the performance of supercapacitors. Here, modified polyhedral oligosilsesquioxane (POSS) is used to improve the electrochemical performance of reduced graphene oxide (rGO) through the enhancement of porosity and the extension of interlayer space between the sheets allowing efficient electrolyte transport. rGO–POSS hybrids exhibited a high specific capacitance of 174 F g−1, power density reaching 2.25 W cm−3, and high energy density of 41.4 mW h cm−3 endowed by the introduction of POSS spacers. Moreover, these electrode materials display excellent durability reaching >98% retention after 5000 cycles. |
Lin, H; Ji, D -K; Lucherelli, M A; Reina, G; Ippolito, S; Samorì, P; Bianco, A Comparative Effects of Graphene and Molybdenum Disulfide on Human Macrophage Toxicity Article de journal Dans: Small, 16 (2002194), 2020. @article{Lin2020, title = {Comparative Effects of Graphene and Molybdenum Disulfide on Human Macrophage Toxicity}, author = {H. Lin and D.-K. Ji and M. A. Lucherelli and G. Reina and S. Ippolito and P. Samorì and A. Bianco}, editor = {Wiley }, url = {https://doi.org/10.1002/smll.202002194}, year = {2020}, date = {2020-08-02}, journal = {Small}, volume = {16}, number = {2002194}, abstract = {Graphene and other 2D materials, such as molybdenum disulfide, have been increasingly used in electronics, composites, and biomedicine. In particular, MoS2 and graphene hybrids have attracted a great interest for applications in the biomedical research, therefore stimulating a pertinent investigation on their safety in immune cells like macrophages, which commonly engulf these materials. In this study, M1 and M2 macrophage viability and activation are mainly found to be unaffected by few‐layer graphene (FLG) and MoS2 at doses up to 50 µg mL−1. The uptake of both materials is confirmed by transmission electron microscopy, inductively coupled plasma mass spectrometry, and inductively coupled plasma atomic emission spectroscopy. Notably, both 2D materials increase the secretion of inflammatory cytokines in M1 macrophages. At the highest dose, FLG decreases CD206 expression while MoS2 decreases CD80 expression. CathB and CathL gene expressions are dose‐dependently increased by both materials. Despite a minimal impact on the autophagic pathway, FLG is found to increase the expression of Atg5 and autophagic flux, as observed by Western blotting of LC3‐II, in M1 macrophages. Overall, FLG and MoS2 are of little toxicity in human macrophages even though they are found to trigger cell stress and inflammatory responses.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Graphene and other 2D materials, such as molybdenum disulfide, have been increasingly used in electronics, composites, and biomedicine. In particular, MoS2 and graphene hybrids have attracted a great interest for applications in the biomedical research, therefore stimulating a pertinent investigation on their safety in immune cells like macrophages, which commonly engulf these materials. In this study, M1 and M2 macrophage viability and activation are mainly found to be unaffected by few‐layer graphene (FLG) and MoS2 at doses up to 50 µg mL−1. The uptake of both materials is confirmed by transmission electron microscopy, inductively coupled plasma mass spectrometry, and inductively coupled plasma atomic emission spectroscopy. Notably, both 2D materials increase the secretion of inflammatory cytokines in M1 macrophages. At the highest dose, FLG decreases CD206 expression while MoS2 decreases CD80 expression. CathB and CathL gene expressions are dose‐dependently increased by both materials. Despite a minimal impact on the autophagic pathway, FLG is found to increase the expression of Atg5 and autophagic flux, as observed by Western blotting of LC3‐II, in M1 macrophages. Overall, FLG and MoS2 are of little toxicity in human macrophages even though they are found to trigger cell stress and inflammatory responses. |
Wang, Y; Gali, S M; Slassi, A; Beljonne, D; Samorì, P Collective Dipole‐Dominated Doping of Monolayer MoS2: Orientation and Magnitude Control via the Supramolecular Approach Article de journal Dans: Adv. Funct. Mater, 30 (2002846), 2020. @article{Wang2020, title = {Collective Dipole‐Dominated Doping of Monolayer MoS2: Orientation and Magnitude Control via the Supramolecular Approach}, author = {Y. Wang and S. M. Gali and A. Slassi and D. Beljonne and P. Samorì}, editor = {Wiley}, url = {https://doi.org/10.1002/adfm.202002846}, year = {2020}, date = {2020-07-12}, journal = {Adv. Funct. Mater}, volume = {30}, number = {2002846}, abstract = {Molecular doping is a powerful, tuneable, and versatile method to modify the electronic properties of 2D transition metal dichalcogenides (TMDCs). While electron transfer is an isotropic process, dipole‐induced doping is a collective phenomenon in which the orientation of the molecular dipoles interfaced to the 2D material is key to modulate and boost this electronic effect, despite it is not yet demonstrated. A novel method toward the molecular functionalization of monolayer MoS2 relying on the molecular self‐assembly of metal phthalocyanine and the orientation‐controlled coordination chemistry of axial ligands is reported here. It is demonstrated that the subtle variation of position and type of functional groups exposed on the pyridinic ligand, yields a molecular dipole with programed magnitude and orientation which is capable to strongly influence the opto‐electronic properties of monolayer MoS2. In particular, experimental results revealed that both p‐ and n‐type doping can be achieved by modulating the charge carrier density up to 4.8 1012 cm−2. Density functional theory calculations showed that the doping mechanism is primarily resulting from the effect of dipole‐induced doping rather than charge transfer. The strategy to dope TMDCs is a highly modulable and robust, and it enables to enrich the functionality of 2D materials‐based devices for high‐performance applications in optoelectronics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular doping is a powerful, tuneable, and versatile method to modify the electronic properties of 2D transition metal dichalcogenides (TMDCs). While electron transfer is an isotropic process, dipole‐induced doping is a collective phenomenon in which the orientation of the molecular dipoles interfaced to the 2D material is key to modulate and boost this electronic effect, despite it is not yet demonstrated. A novel method toward the molecular functionalization of monolayer MoS2 relying on the molecular self‐assembly of metal phthalocyanine and the orientation‐controlled coordination chemistry of axial ligands is reported here. It is demonstrated that the subtle variation of position and type of functional groups exposed on the pyridinic ligand, yields a molecular dipole with programed magnitude and orientation which is capable to strongly influence the opto‐electronic properties of monolayer MoS2. In particular, experimental results revealed that both p‐ and n‐type doping can be achieved by modulating the charge carrier density up to 4.8 1012 cm−2. Density functional theory calculations showed that the doping mechanism is primarily resulting from the effect of dipole‐induced doping rather than charge transfer. The strategy to dope TMDCs is a highly modulable and robust, and it enables to enrich the functionality of 2D materials‐based devices for high‐performance applications in optoelectronics. |
Liu, Z; Qiu, H; Wang, C; Chen, Z; Zyska, B; Narita, A; Ciesielski, A; Hecht, S; Chi, L; Müllen, K; Samorì, P Photomodulation of Charge Transport in All‐Semiconducting 2D–1D van der Waals Heterostructures with Suppressed Persistent Photoconductivity Effect Article de journal Dans: Advanced Materials, 32 , p. 2001268, 2020. @article{Liu2020, title = {Photomodulation of Charge Transport in All‐Semiconducting 2D–1D van der Waals Heterostructures with Suppressed Persistent Photoconductivity Effect}, author = {Z. Liu and H. Qiu and C. Wang and Z. Chen and B. Zyska and A. Narita and A. Ciesielski and S. Hecht and L. Chi and K. Müllen and P. Samorì}, editor = {Wiley Online Library }, url = {https://doi.org/10.1002/adma.202001268}, year = {2020}, date = {2020-07-02}, journal = {Advanced Materials}, volume = {32}, pages = {2001268}, abstract = {Van der Waals heterostructures (VDWHs), obtained via the controlled assembly of 2D atomically thin crystals, exhibit unique physicochemical properties, rendering them prototypical building blocks to explore new physics and for applications in optoelectronics. As the emerging alternatives to graphene, monolayer transition metal dichalcogenides and bottom‐up synthesized graphene nanoribbons (GNRs) are promising candidates for overcoming the shortcomings of graphene, such as the absence of a bandgap in its electronic structure, which is essential in optoelectronics. Herein, VDWHs comprising GNRs onto monolayer MoS2 are fabricated. Field‐effect transistors (FETs) based on such VDWHs show an efficient suppression of the persistent photoconductivity typical of MoS2, resulting from the interfacial charge transfer process. The MoS2‐GNR FETs exhibit drastically reduced hysteresis and more stable behavior in the transfer characteristics, which is a prerequisite for the further photomodulation of charge transport behavior within the MoS2‐GNR VDWHs. The physisorption of photochromic molecules onto the MoS2‐GNR VDWHs enables reversible light‐driven control over charge transport. In particular, the drain current of the MoS2‐GNR FET can be photomodulated by 52%, without displaying significant fatigue over at least 10 cycles. Moreover, four distinguishable output current levels can be achieved, demonstrating the great potential of MoS2‐GNR VDWHs for multilevel memory devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Van der Waals heterostructures (VDWHs), obtained via the controlled assembly of 2D atomically thin crystals, exhibit unique physicochemical properties, rendering them prototypical building blocks to explore new physics and for applications in optoelectronics. As the emerging alternatives to graphene, monolayer transition metal dichalcogenides and bottom‐up synthesized graphene nanoribbons (GNRs) are promising candidates for overcoming the shortcomings of graphene, such as the absence of a bandgap in its electronic structure, which is essential in optoelectronics. Herein, VDWHs comprising GNRs onto monolayer MoS2 are fabricated. Field‐effect transistors (FETs) based on such VDWHs show an efficient suppression of the persistent photoconductivity typical of MoS2, resulting from the interfacial charge transfer process. The MoS2‐GNR FETs exhibit drastically reduced hysteresis and more stable behavior in the transfer characteristics, which is a prerequisite for the further photomodulation of charge transport behavior within the MoS2‐GNR VDWHs. The physisorption of photochromic molecules onto the MoS2‐GNR VDWHs enables reversible light‐driven control over charge transport. In particular, the drain current of the MoS2‐GNR FET can be photomodulated by 52%, without displaying significant fatigue over at least 10 cycles. Moreover, four distinguishable output current levels can be achieved, demonstrating the great potential of MoS2‐GNR VDWHs for multilevel memory devices. |
Kang, J; Huang, S; Jiang, K; Lu, C; Chen, Z; Zhu, J; Yang, C; Ciesielski, A; Qiu, F; Zhuang, X 2D Porous Polymers with sp2‐Carbon Connections and Sole sp2‐Carbon Skeletons Article de journal Dans: Advanced Functional Materials, 30 , p. 2000857, 2020. @article{Kang2020, title = {2D Porous Polymers with sp2‐Carbon Connections and Sole sp2‐Carbon Skeletons}, author = {J. Kang and S. Huang and K. Jiang and C. Lu and Z. Chen and J. Zhu and C. Yang and A. Ciesielski and F. Qiu and X. Zhuang}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adfm.202000857}, year = {2020}, date = {2020-07-02}, journal = {Advanced Functional Materials}, volume = {30}, pages = {2000857}, abstract = {2D porous polymers with a planar architecture and high specific surface area have significant applications potential, such as for photocatalysis, electrochemical catalysis, gas storage and separation, and sensing. Such 2D porous polymers have generally been classified as 2D metal–organic frameworks, 2D covalent organic frameworks, graphitic carbon nitride, graphdiyne, and sandwich‐like porous polymer nanosheets. Among these, 2D porous polymers with sp2‐hybridized carbon ( C s p 2 ) bonding are an emerging field of interest. Compared with 2D porous polymers linked by B-O, C=N, or CC bonds, C s p 2 ‐linked 2D porous polymers exhibit extended electron delocalization resulting in unique optical/electrical properties, as well as high chemical/photostability and tunable electrochemical performance. Furthermore, such 2D porous polymers are one of the best precursors for the fabrication of 2D porous carbon materials and carbon skeletons with atomically dispersed transition‐metal active sites. Herein, rational synthetic approaches for 2D porous polymers with C s p 2 bonding are summarized. Their current practical photoelectric applications, including for gas separation, luminescent sensing and imaging, electrodes for batteries and supercapacitors, and photocatalysis are also discussed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } 2D porous polymers with a planar architecture and high specific surface area have significant applications potential, such as for photocatalysis, electrochemical catalysis, gas storage and separation, and sensing. Such 2D porous polymers have generally been classified as 2D metal–organic frameworks, 2D covalent organic frameworks, graphitic carbon nitride, graphdiyne, and sandwich‐like porous polymer nanosheets. Among these, 2D porous polymers with sp2‐hybridized carbon ( C s p 2 ) bonding are an emerging field of interest. Compared with 2D porous polymers linked by B-O, C=N, or CC bonds, C s p 2 ‐linked 2D porous polymers exhibit extended electron delocalization resulting in unique optical/electrical properties, as well as high chemical/photostability and tunable electrochemical performance. Furthermore, such 2D porous polymers are one of the best precursors for the fabrication of 2D porous carbon materials and carbon skeletons with atomically dispersed transition‐metal active sites. Herein, rational synthetic approaches for 2D porous polymers with C s p 2 bonding are summarized. Their current practical photoelectric applications, including for gas separation, luminescent sensing and imaging, electrodes for batteries and supercapacitors, and photocatalysis are also discussed. |
Fenwick, O; Coutiño-Gonzalez, E; Richard, F; Bonacchi, S; Baekelant, W; de Vos, D; Roeffaers, M B J; Hofkens, J; Samorì, P X‐Ray‐Induced Growth Dynamics of Luminescent Silver Clusters in Zeolites Article de journal Dans: Small, 16 , p. 2002063, 2020. @article{Fenwick2020, title = {X‐Ray‐Induced Growth Dynamics of Luminescent Silver Clusters in Zeolites}, author = {O. Fenwick and E. Coutiño-Gonzalez and F. Richard and S. Bonacchi and W. Baekelant and D. de Vos and M. B. J. Roeffaers and J. Hofkens and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/smll.202002063}, year = {2020}, date = {2020-07-02}, journal = {Small}, volume = {16}, pages = {2002063}, abstract = {Herein, AlKα X‐rays are used to drive the growth of luminescent silver clusters in zeolites. The growth of the silver species is tracked using Auger spectroscopy and fluorescence microscopy, by monitoring the evolution from their ions to luminescent clusters and then metallic, dark nanoparticles. It is shown that the growth rate in different zeolites is determined by the mobility of the silver ions in the framework and that the growth dynamics in calcined samples obeys the Hill–Langmuir equation for noncooperative binding. Comparison of the optical properties of X‐ray‐grown silver clusters with silver clusters formed by standard heat treatment indicates that the latter have a higher specificity toward the formation of luminescent clusters of a specific (small) nuclearity, whereas the former produce a wide distribution of cluster species as well as larger nanoparticles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Herein, AlKα X‐rays are used to drive the growth of luminescent silver clusters in zeolites. The growth of the silver species is tracked using Auger spectroscopy and fluorescence microscopy, by monitoring the evolution from their ions to luminescent clusters and then metallic, dark nanoparticles. It is shown that the growth rate in different zeolites is determined by the mobility of the silver ions in the framework and that the growth dynamics in calcined samples obeys the Hill–Langmuir equation for noncooperative binding. Comparison of the optical properties of X‐ray‐grown silver clusters with silver clusters formed by standard heat treatment indicates that the latter have a higher specificity toward the formation of luminescent clusters of a specific (small) nuclearity, whereas the former produce a wide distribution of cluster species as well as larger nanoparticles. |
Ji, D -K; Reina, G; Guo, S; Eredia, M; Samorì, P; Ménard-Moyon, C; Bianco, A Controlled functionalization of carbon nanodots for targeted intracellular production of reactive oxygen species Article de journal Dans: Nanoscale Horiz., 5 , p. 1240–1249, 2020. @article{Ji2020, title = {Controlled functionalization of carbon nanodots for targeted intracellular production of reactive oxygen species}, author = {D.-K. Ji and G. Reina and S. Guo and M. Eredia and P. Samorì and C. Ménard-Moyon and A. Bianco}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d0nh00300j}, year = {2020}, date = {2020-06-10}, journal = {Nanoscale Horiz.}, volume = {5}, pages = {1240–1249}, abstract = {Controlled intracellular release of exogenous reactive oxygen species (ROS) is an innovative and efficient strategy for cancer treatment. Well-designed materials, which can produce ROS in targeted cells, minimizing side effects, still need to be explored as new generation nanomedicines. Here, red-emissive carbon nanodots (CNDs) with intrinsic theranostic properties are devised, and further modified with folic acid (FA) ligand through a controlled covalent functionalization for targeted cell imaging and intracellular production of ROS. We demonstrated that covalent functionalization is an effective strategy to prevent the aggregation of the dots, leading to superior colloidal stability, enhanced luminescence and ROS generation. Indeed, the functional nanodots possess a deep-red emission and good dispersibility under physiological conditions. Importantly, they show excellent targeting properties and generation of high levels of ROS under 660 nm laser irradiation, leading to efficient cell death. These unique properties enable FA-modified carbon nanodots to act as a multifunctional nanoplatform for simultaneous targeted imaging and efficient photodynamic therapy to induce cancer cell death.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Controlled intracellular release of exogenous reactive oxygen species (ROS) is an innovative and efficient strategy for cancer treatment. Well-designed materials, which can produce ROS in targeted cells, minimizing side effects, still need to be explored as new generation nanomedicines. Here, red-emissive carbon nanodots (CNDs) with intrinsic theranostic properties are devised, and further modified with folic acid (FA) ligand through a controlled covalent functionalization for targeted cell imaging and intracellular production of ROS. We demonstrated that covalent functionalization is an effective strategy to prevent the aggregation of the dots, leading to superior colloidal stability, enhanced luminescence and ROS generation. Indeed, the functional nanodots possess a deep-red emission and good dispersibility under physiological conditions. Importantly, they show excellent targeting properties and generation of high levels of ROS under 660 nm laser irradiation, leading to efficient cell death. These unique properties enable FA-modified carbon nanodots to act as a multifunctional nanoplatform for simultaneous targeted imaging and efficient photodynamic therapy to induce cancer cell death. |
Hou, L; Leydecker, T; Zhang, X; Rekab, W; Herder, M; C. Cendra, Hecht S; McCulloch, I; Salleo, A; Orgiu, E; Samorì, P Engineering Optically Switchable Transistors with Improved Performance by Controlling Interactions of Diarylethenes in Polymer Matrices Article de journal Dans: Journal of the American Chemical Society, 42 , p. 11050–11059, 2020. @article{Hou2020, title = {Engineering Optically Switchable Transistors with Improved Performance by Controlling Interactions of Diarylethenes in Polymer Matrices}, author = {L. Hou and T. Leydecker and X. Zhang and W. Rekab and M. Herder and C. Cendra, S. Hecht and I. McCulloch and A. Salleo and E. Orgiu and P. Samorì}, editor = { American Chemical Society }, url = {https://doi.org/10.1021/jacs.0c02961}, year = {2020}, date = {2020-06-02}, journal = {Journal of the American Chemical Society}, volume = {42}, pages = {11050–11059}, abstract = {The integration of photochromic molecules into semiconducting polymer matrices via blending has recently attracted a great deal of attention, as it provides the means to reversibly modulate the output signal of electronic devices by using light as a remote control. However, the structural and electronic interactions between photochromic molecules and semiconducting polymers are far from being fully understood. Here we perform a comparative investigation by combining two photochromic diarylethene moieties possessing similar energy levels yet different propensity to aggregate with five prototypical polymer semiconductors exhibiting different energy levels and structural order, ranging from amorphous to semicrystalline. Our in-depth photochemical, structural, morphological, and electrical characterization reveals that the photoresponsive behavior of thin-film transistors including polymer/diarylethenes blends as the active layer is governed by a complex interplay between the relative position of the energy levels and the polymer matrix microstructure. By matching the energy levels and optimizing the molecular packing, high-performance optically switchable organic thin-film transistors were fabricated. These findings represent a major step forward in the fabrication of light-responsive organic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The integration of photochromic molecules into semiconducting polymer matrices via blending has recently attracted a great deal of attention, as it provides the means to reversibly modulate the output signal of electronic devices by using light as a remote control. However, the structural and electronic interactions between photochromic molecules and semiconducting polymers are far from being fully understood. Here we perform a comparative investigation by combining two photochromic diarylethene moieties possessing similar energy levels yet different propensity to aggregate with five prototypical polymer semiconductors exhibiting different energy levels and structural order, ranging from amorphous to semicrystalline. Our in-depth photochemical, structural, morphological, and electrical characterization reveals that the photoresponsive behavior of thin-film transistors including polymer/diarylethenes blends as the active layer is governed by a complex interplay between the relative position of the energy levels and the polymer matrix microstructure. By matching the energy levels and optimizing the molecular packing, high-performance optically switchable organic thin-film transistors were fabricated. These findings represent a major step forward in the fabrication of light-responsive organic devices. |
Parkula, V; Berto, M; Diacci, C; Patrahau, B; Lauro, Di M; Kovtun, A; Liscio, A; Sensi, M; Samorì, P; Greco, P; Bortolotti, C A; Biscarini, F Harnessing Selectivity and Sensitivity in Electronic Biosensing: A Novel Lab-on-Chip Multigate Organic Transistor Article de journal Dans: Anal. Chem., 92 , p. 9330–9337, 2020. @article{Parkula2020, title = {Harnessing Selectivity and Sensitivity in Electronic Biosensing: A Novel Lab-on-Chip Multigate Organic Transistor}, author = {V. Parkula and M. Berto and C. Diacci and B. Patrahau and M. Di Lauro and A. Kovtun and A. Liscio and M. Sensi and P. Samorì and P. Greco and C. A. Bortolotti and F. Biscarini}, editor = {ACS}, url = {https://doi.org/10.1021/acs.analchem.0c01655}, year = {2020}, date = {2020-06-02}, journal = {Anal. Chem.}, volume = {92}, pages = {9330–9337}, abstract = {Electrolyte gated organic transistors can operate as powerful ultrasensitive biosensors, and efforts are currently devoted to devising strategies for reducing the contribution of hardly avoidable, nonspecific interactions to their response, to ultimately harness selectivity in the detection process. We report a novel lab-on-a-chip device integrating a multigate electrolyte gated organic field-effect transistor (EGOFET) with a 6.5 μL microfluidics set up capable to provide an assessment of both the response reproducibility, by enabling measurement in triplicate, and of the device selectivity through the presence of an internal reference electrode. As proof-of-concept, we demonstrate the efficient operation of our pentacene based EGOFET sensing platform through the quantification of tumor necrosis factor alpha with a detection limit as low as 3 pM. Sensing of inflammatory cytokines, which also include TNFα, is of the outmost importance for monitoring a large number of diseases. The multiplexable organic electronic lab-on-chip provides a statistically solid, reliable, and selective response on microliters sample volumes on the minutes time scale, thus matching the relevant key-performance indicators required in point-of-care diagnostics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electrolyte gated organic transistors can operate as powerful ultrasensitive biosensors, and efforts are currently devoted to devising strategies for reducing the contribution of hardly avoidable, nonspecific interactions to their response, to ultimately harness selectivity in the detection process. We report a novel lab-on-a-chip device integrating a multigate electrolyte gated organic field-effect transistor (EGOFET) with a 6.5 μL microfluidics set up capable to provide an assessment of both the response reproducibility, by enabling measurement in triplicate, and of the device selectivity through the presence of an internal reference electrode. As proof-of-concept, we demonstrate the efficient operation of our pentacene based EGOFET sensing platform through the quantification of tumor necrosis factor alpha with a detection limit as low as 3 pM. Sensing of inflammatory cytokines, which also include TNFα, is of the outmost importance for monitoring a large number of diseases. The multiplexable organic electronic lab-on-chip provides a statistically solid, reliable, and selective response on microliters sample volumes on the minutes time scale, thus matching the relevant key-performance indicators required in point-of-care diagnostics. |
Carroli, M; Duong, D T; Buchaca-Domingo, E; Liscio, A; Börjesson, K; Herder, M; Palermo, V; Hecht, S; Stingelin, N; Salleo, A; Orgiu, E; Samorì, P The Role of Morphology in Optically Switchable Transistors Based on a Photochromic Molecule/p‐Type Polymer Semiconductor Blend Article de journal Dans: Adv. Funct. Mater., 30 , p. 1907507, 2020. @article{Carroli2020, title = {The Role of Morphology in Optically Switchable Transistors Based on a Photochromic Molecule/p‐Type Polymer Semiconductor Blend}, author = {M. Carroli and D. T. Duong and E. Buchaca-Domingo and A. Liscio and K. Börjesson and M. Herder and V. Palermo and S. Hecht and N. Stingelin and A. Salleo and E. Orgiu and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adfm.201907507}, year = {2020}, date = {2020-05-15}, journal = {Adv. Funct. Mater.}, volume = {30}, pages = {1907507}, abstract = {The correlation between morphology and optoelectronic performance in organic thin‐film transistors based on blends of photochromic diarylethenes (DAE) and poly(3‐hexylthiophene) (P3HT) is investigated by varying molecular weight (Mw = 20–100 kDa) and regioregularity of the conjugated polymer as well as the temperature of thermal annealing (rt‐160 °C) in thin films. Semicrystalline architectures of P3HT/DAE blends comprise crystalline domains, ensuring efficient charge transport, and less aggregated regions, where DAEs are located as a result of their spontaneous expulsion from the crystalline domains during the self‐assembly. The best compromise between field‐effect mobility (μ) and switching capabilities is observed in blends containing P3HT with Mw = 50 kDa, exhibiting μ as high as 1 × 10−3 cm2 V−1 s−1 combined with a >50% photoswitching ratio. Higher or lower Mw than 50 kDa are found to be detrimental for field‐effect mobility and to lead to reduced device current switchability. The microstructure of the regioregular P3HT blend is found to be sensitive to the thermal annealing temperature, with an increase in μ and a decrease in current modulation being observed as a response to the light‐stimulus likely due to an increased P3HT‐DAE segregation, partially hindering DAE photoisomerization. The findings demonstrate the paramount importance of fine tuning the structure and morphology of bicomponent films for leveraging the multifunctional nature of optoelectronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The correlation between morphology and optoelectronic performance in organic thin‐film transistors based on blends of photochromic diarylethenes (DAE) and poly(3‐hexylthiophene) (P3HT) is investigated by varying molecular weight (Mw = 20–100 kDa) and regioregularity of the conjugated polymer as well as the temperature of thermal annealing (rt‐160 °C) in thin films. Semicrystalline architectures of P3HT/DAE blends comprise crystalline domains, ensuring efficient charge transport, and less aggregated regions, where DAEs are located as a result of their spontaneous expulsion from the crystalline domains during the self‐assembly. The best compromise between field‐effect mobility (μ) and switching capabilities is observed in blends containing P3HT with Mw = 50 kDa, exhibiting μ as high as 1 × 10−3 cm2 V−1 s−1 combined with a >50% photoswitching ratio. Higher or lower Mw than 50 kDa are found to be detrimental for field‐effect mobility and to lead to reduced device current switchability. The microstructure of the regioregular P3HT blend is found to be sensitive to the thermal annealing temperature, with an increase in μ and a decrease in current modulation being observed as a response to the light‐stimulus likely due to an increased P3HT‐DAE segregation, partially hindering DAE photoisomerization. The findings demonstrate the paramount importance of fine tuning the structure and morphology of bicomponent films for leveraging the multifunctional nature of optoelectronic devices. |
Iglesias, D; Ippolito, S; Ciesielski, A; Samorì, P Simultaneous non-covalent bi-functionalization of 1T-MoS2 ruled by electrostatic interactions: towards multi-responsive materials Article de journal Dans: Chemical Communications, 56 , p. 6878–6881, 2020. @article{Iglesias2020, title = {Simultaneous non-covalent bi-functionalization of 1T-MoS2 ruled by electrostatic interactions: towards multi-responsive materials}, author = {D. Iglesias and S. Ippolito and A. Ciesielski and P. Samorì}, editor = {Royal Society of Chemistry}, url = {https://doi.org/10.1039/d0cc02371j}, year = {2020}, date = {2020-04-29}, journal = {Chemical Communications}, volume = {56}, pages = {6878–6881}, abstract = {Dual functionalization of chemically exfoliated MoS2 has been achieved by exploiting coulombic interactions among positively charged molecules and the negatively charged 2D flakes. The reversibility and kinetics of the process have been studied by spectroscopic tools. The hybrid material has been transferred to various substrates, yielding multifunctional robust flexible films.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dual functionalization of chemically exfoliated MoS2 has been achieved by exploiting coulombic interactions among positively charged molecules and the negatively charged 2D flakes. The reversibility and kinetics of the process have been studied by spectroscopic tools. The hybrid material has been transferred to various substrates, yielding multifunctional robust flexible films. |
Huang, C -B; Ciesielski, A; Samorì, P Molecular Springs: Integration of Complex Dynamic Architectures into Functional Devices Article de journal Dans: Angew. Chem. Int. Ed. 2020, 59 , p. 7319–7330, 2020. @article{Huang2020, title = {Molecular Springs: Integration of Complex Dynamic Architectures into Functional Devices}, author = {C.-B. Huang and A. Ciesielski and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/anie.201914931}, year = {2020}, date = {2020-04-22}, journal = {Angew. Chem. Int. Ed. 2020}, volume = {59}, pages = {7319–7330}, abstract = {Molecular/supramolecular springs are artificial nanoscale objects possessing well‐defined structures and tunable physicochemical properties. Like a macroscopic spring, supramolecular springs are capable of switching their nanoscale conformation as a response to external stimuli by undergoing mechanical spring‐like motions. This dynamic action offers intriguing opportunities for engineering molecular nanomachines by translating the stimuli‐responsive nanoscopic motions into macroscopic work. These nanoscopic objects are reversible dynamic multifunctional architectures which can express a variety of novel properties and behave as adaptive nanoscopic systems. In this Minireview, we focus on the design and structure–property relationships of supramolecular springs and their (self‐)assembly as a prerequisite towards the generation of novel dynamic materials featuring controlled movements to be readily integrated into macroscopic devices for applications in sensing, robotics, and the internet of things.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular/supramolecular springs are artificial nanoscale objects possessing well‐defined structures and tunable physicochemical properties. Like a macroscopic spring, supramolecular springs are capable of switching their nanoscale conformation as a response to external stimuli by undergoing mechanical spring‐like motions. This dynamic action offers intriguing opportunities for engineering molecular nanomachines by translating the stimuli‐responsive nanoscopic motions into macroscopic work. These nanoscopic objects are reversible dynamic multifunctional architectures which can express a variety of novel properties and behave as adaptive nanoscopic systems. In this Minireview, we focus on the design and structure–property relationships of supramolecular springs and their (self‐)assembly as a prerequisite towards the generation of novel dynamic materials featuring controlled movements to be readily integrated into macroscopic devices for applications in sensing, robotics, and the internet of things. |
Zhao, Y; Bertolazzi, S; Maglione, M S; Rovira, C; Mas-Torrent, M; Samorì, P Molecular Approach to Electrochemically Switchable Monolayer MoS2 Transistors Article de journal Dans: Advanced Materials, 32 (2000740), 2020. @article{Zhao2020, title = {Molecular Approach to Electrochemically Switchable Monolayer MoS2 Transistors}, author = {Y. Zhao and S. Bertolazzi and M. S. Maglione and C. Rovira and M. Mas-Torrent and P. Samorì}, editor = {Wiley Online Library}, url = {https://doi.org/10.1002/adma.202000740}, year = {2020}, date = {2020-04-02}, journal = {Advanced Materials}, volume = {32}, number = {2000740}, abstract = {As Moore's law is running to its physical limit, tomorrow's electronic systems can be leveraged to a higher value by integrating “More than Moore” technologies into CMOS digital circuits. The hybrid heterostructure composed of two‐dimensional (2D) semiconductors and molecular materials represents a powerful strategy to confer new properties to the former components, realize stimuli‐responsive functional devices, and enable diversification in “More than Moore” technologies. Here, an ionic liquid (IL) gated 2D MoS2 field‐effect transistor (FET) with molecular functionalization is fabricated. The suitably designed ferrocene‐substituted alkanethiol molecules not only improve the FET performance, but also show reversible electrochemical switching on the surface of MoS2. Field‐effect mobility of monolayer MoS2 reaches values as high as ≈116 cm2 V−1 s−1 with Ion/Ioff ratio exceeding 105. Molecules in their neutral or charged state impose distinct doping effect, efficiently tuning the electron density in monolayer MoS2. It is noteworthy that the joint doping effect from IL and switchable molecules results in the steep subthreshold swing of MoS2 FET in the backward sweep. These results demonstrate that the device architecture represents an unprecedented and powerful strategy to fabricate switchable 2D FET with a chemically programmed electrochemical signal as a remote control, paving the road toward novel functional devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } As Moore's law is running to its physical limit, tomorrow's electronic systems can be leveraged to a higher value by integrating “More than Moore” technologies into CMOS digital circuits. The hybrid heterostructure composed of two‐dimensional (2D) semiconductors and molecular materials represents a powerful strategy to confer new properties to the former components, realize stimuli‐responsive functional devices, and enable diversification in “More than Moore” technologies. Here, an ionic liquid (IL) gated 2D MoS2 field‐effect transistor (FET) with molecular functionalization is fabricated. The suitably designed ferrocene‐substituted alkanethiol molecules not only improve the FET performance, but also show reversible electrochemical switching on the surface of MoS2. Field‐effect mobility of monolayer MoS2 reaches values as high as ≈116 cm2 V−1 s−1 with Ion/Ioff ratio exceeding 105. Molecules in their neutral or charged state impose distinct doping effect, efficiently tuning the electron density in monolayer MoS2. It is noteworthy that the joint doping effect from IL and switchable molecules results in the steep subthreshold swing of MoS2 FET in the backward sweep. These results demonstrate that the device architecture represents an unprecedented and powerful strategy to fabricate switchable 2D FET with a chemically programmed electrochemical signal as a remote control, paving the road toward novel functional devices. |
Luo, H; Dimitrov, S; Daboczi, M; Kim, J -S; Guo, Q; Fang, Y; Stoeckel, M -A; Samorì, P; Fenwick, O; Sobrido, Jorge A B; Wang, X; Titirici, M -M Nitrogen-Doped Carbon Dots/TiO2 Nanoparticle Composites for Photoelectrochemical Water Oxidation Article de journal Dans: ACS Appl. Nano Mater., 3 (4), p. 3371–3381, 2020. @article{Luo2020, title = {Nitrogen-Doped Carbon Dots/TiO2 Nanoparticle Composites for Photoelectrochemical Water Oxidation}, author = {H. Luo and S. Dimitrov and M. Daboczi and J.-S. Kim and Q. Guo and Y. Fang and M.-A. Stoeckel and P. Samorì and O. Fenwick and A. B. Jorge Sobrido and X. Wang and M.-M. Titirici}, editor = {ACS Publcation}, url = {https://doi.org/10.1021/acsanm.9b02412}, year = {2020}, date = {2020-03-20}, journal = {ACS Appl. Nano Mater.}, volume = {3}, number = {4}, pages = {3371–3381}, abstract = {Carbon dots on photoactive semiconductor nanomaterials have represented an effective strategy for enhancing their photoelectrochemical (PEC) activity. By carefully designing and manipulating a carbon dot/support composite, a high photocurrent could be obtained. Currently, there is not much fundamental understanding of how the interaction between such materials can facilitate the reaction process. This hinders the wide applicability of PEC devices. To address this need of improving the fundamental understanding of the carbon dots/semiconductor nanocomposite, we have taken the TiO2 case as a model semiconductor system with nitrogen-doped carbon dots (NCDs). We present here with in-depth investigation of the structural hybridization and energy transitions in the NCDs/TiO2 photoelectrode via high-resolution scanning transmission microscopy (HR-STEM), electron energy loss spectroscopy (EELS), UV–vis absorption, electrochemical impedance spectroscopy (EIS), Mott–Schottky (M–S), time-correlated single-photon counting (TCSPC), and ultraviolet photoelectron spectroscopy (UPS), which shed some light on the charge-transfer process at the carbon dots and TiO2 interface. We show that N doping in carbon dots can effectively prolong the carrier lifetime, and the hybridization of NCDs and TiO2 is able not only to extend TiO2 light response into the visible range but also to form a heterojunction at the NCDs/TiO2 interface with a properly aligned band structure that allows a spatial separation of the charges. This work is arguably the first to report the direct probing of the band positions of the carbon dot–TiO2 nanoparticle composite in a PEC system for understanding the energy-transfer mechanism, demonstrating the favorable role of NCDs in the photocurrent response of TiO2 for the water oxidation process. This study reveals the importance of combining structural, photophysical, and electrochemical experiments to develop a comprehensive understanding of the nanoscale charge-transfer processes between the carbon dots and their catalyst supports.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Carbon dots on photoactive semiconductor nanomaterials have represented an effective strategy for enhancing their photoelectrochemical (PEC) activity. By carefully designing and manipulating a carbon dot/support composite, a high photocurrent could be obtained. Currently, there is not much fundamental understanding of how the interaction between such materials can facilitate the reaction process. This hinders the wide applicability of PEC devices. To address this need of improving the fundamental understanding of the carbon dots/semiconductor nanocomposite, we have taken the TiO2 case as a model semiconductor system with nitrogen-doped carbon dots (NCDs). We present here with in-depth investigation of the structural hybridization and energy transitions in the NCDs/TiO2 photoelectrode via high-resolution scanning transmission microscopy (HR-STEM), electron energy loss spectroscopy (EELS), UV–vis absorption, electrochemical impedance spectroscopy (EIS), Mott–Schottky (M–S), time-correlated single-photon counting (TCSPC), and ultraviolet photoelectron spectroscopy (UPS), which shed some light on the charge-transfer process at the carbon dots and TiO2 interface. We show that N doping in carbon dots can effectively prolong the carrier lifetime, and the hybridization of NCDs and TiO2 is able not only to extend TiO2 light response into the visible range but also to form a heterojunction at the NCDs/TiO2 interface with a properly aligned band structure that allows a spatial separation of the charges. This work is arguably the first to report the direct probing of the band positions of the carbon dot–TiO2 nanoparticle composite in a PEC system for understanding the energy-transfer mechanism, demonstrating the favorable role of NCDs in the photocurrent response of TiO2 for the water oxidation process. This study reveals the importance of combining structural, photophysical, and electrochemical experiments to develop a comprehensive understanding of the nanoscale charge-transfer processes between the carbon dots and their catalyst supports. |
