@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}
}

@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}
}

@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}
}

@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}
}

@article{Czepa2020,
title = {Graphene oxide-mesoporous SiO2 hybrid composite for fast and efficient removal of organic cationic contaminants},
author = {W. Czepa and D. Pakulski and S. Witomska and V. Patroniak and A. Ciesielski and P. Samorì},
editor = {Science Direct and ELSEVIER},
url = {https://doi.org/10.1016/j.carbon.2019.11.091},
year = {2020},
date = {2020-03-01},
journal = {Carbon},
volume = {158},
pages = {193–201},
abstract = {In this study, we have developed a novel mesoporous SiO2 - graphene oxide hybrid material (SiO2NH2-GO) as highly efficient adsorbent for removal of cationic organic dyes from water. The fabrication of such a three-dimensional (3D) SiO2NH2-GO composite has been achieved via the condensation reaction between the amine units exposed on 3-aminopropyl-functionalized silica nanoparticles and the epoxy groups on surface of GO. As a proof-of-concept, SiO2NH2-GO was used for the removal of archetypical dyes from water and revealed outstanding maximum adsorption capacity towards methylene blue (MB), rhodamine B (RhB) and methyl violet (MV) at pH 10 reaching 300, 358 and 178 mg g−1 for MB, RhB and MV, respectively, thus outperforming the neat components of composite, i.e. GO and SiO2. Moreover, the adsorption process revealed that ∼99.7% of MB, RhB and MV have been removed in only 3 min thereby highlighting the superior nature of SiO2NH2-GO composite with respect to most of graphene oxide-based adsorbents of organic dyes. Finally, the composite was used in solid phase extraction (SPE) as column packing material, for continuous water purification, thus highlighting the great potential of SiO2NH2-GO for the large-scale removal of cationic dyes from aqueous solutions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Rekab2020,
title = {Phototuning Selectively Hole and Electron Transport in Optically Switchable Ambipolar Transistors},
author = {W. Rekab and T. Leydecker and L. Hou and H. Chen and M. Kirkus and C. Cendra and M. Herder and S. Hecht and A. Salleo and I. McCulloch and E. Orgiu and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adfm.201908944},
year = {2020},
date = {2020-01-29},
journal = {Adv. Funct. Mater},
volume = {30},
number = {1908944},
abstract = {One of the grand challenges in organic electronics is to develop multicomponent materials wherein each component imparts a different and independently addressable property to the hybrid system. In this way, the combination of the pristine properties of each component is not only preserved but also combined with unprecedented properties emerging from the mutual interaction between the components. Here for the first time, that tri‐component materials comprised of an ambipolar diketopyrrolopyrrole‐based semiconducting polymer combined with two different photochromic diarylethene molecules possessing ad hoc energy levels can be used to develop organic field‐effect transistors, in which the transport of both, holes and electrons, can be photo‐modulated. A fully reversible light‐switching process is demonstrated, with a light‐controlled 100‐fold modulation of p‐type charge transport and a tenfold modulation of n‐type charge transport. These findings pave the way for photo‐tunable inverters and ultimately for completely re‐addressable high‐performance circuits comprising optical storage units and ambipolar field‐effect transistors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Backes2020,
title = {Production and processing of graphene and related materials},
author = {C. Backes, A. M. Abdelkader, C. Alonso, A. Andrieux-Ledier, R. Arenal, J. Azpeitia, N. Balakrishnan, L. Banszerus, J. Barjon, R. Bartali, S. Bellani, C. Berger, R. Berger, M. M. Bernal Ortega, C. Bernard, P. H. Beton, A. Beyer, A. Bianco, P. Bøggild, F. Bonaccorso, G. Borin Barin, C. Botas, R. A. Bueno, D. Carriazo, A. Castellanos-Gomez, M. Christian, A. Ciesielski, T. Ciuk, M. T. Cole, J. Coleman, C. Coletti, L. Crema, H. Cun, D. Dasler, D. De Fazio, N. Díez, S. Drieschner, G. S. Duesberg, R. Fasel, X. Feng, A. Fina, S. Forti, C. Galiotis, G. Garberoglio, J. M. García, J. A. Garrido, M. Gibertini, A. Gölzhäuser, J. Gómez, T. Greber, F. Hauke, A. Hemmi, I. Hernandez-Rodriguez, A. Hirsch, S. A. Hodge, Y. Huttel, P. U. Jepsen, I. Jimenez, U. Kaiser, T. Kaplas, H. Kim, A. Kis, K. Papagelis, K. Kostarelos, A. Krajewska, K. Lee, C. Li, H. Lipsanen, A. Liscio, M. R. Lohe, A. Loiseau, L. Lombardi, M. F. López, O. Martin, C. Martín, L. Martínez, J. A. Martin-Gago, J. I. Martínez, N. Marzari, A. Mayoral, J. McManus, M. Melucci, J. Méndez, C. Merino, P. Merino, A. P. Meyer, E. Miniussi, V. Miseikis, N. Mishra, V. Morandi, C. Munuera, R. Muñoz, H. Nolan, L. Ortolani, A. K. Ott, I. Palacio, V. Palermo, J. Parthenios, I. Pasternak, A. Patane, M. Prato, H. Prevost, V. Prudkovskiy, N. Pugno, T. Rojo, A. Rossi, P. Ruffieux, P. Samorì, L. Schué, E. Setijadi, T. Seyller, G. Speranza, C. Stampfer, I. Stenger, W. Strupinski, Y. Svirko, S. Taioli, K. B. K. Teo, M. Testi, F. Tomarchio, M. Tortello, E. Treossi, A. Turchanin, E. Vazquez, E. Villaro, P. R. Whelan, Z. Xia, R. Yakimova, S. Yang, G. R. Yazdi, C. Yim, D. Yoon, X. Zhang, X. Zhuang, L. Colombo, A. C. Ferrari, M. Garcia-Hernandez},
editor = {IOPSCIENCE},
url = {https://doi.org/10.1088/2053-1583/ab1e0a},
year = {2020},
date = {2020-01-29},
journal = {2D Materials},
volume = {7},
number = {2},
pages = {022001},
abstract = {We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a 'hands-on' approach, providing practical details and procedures as derived from literature as well as from the authors' experience, in order to enable the reader to reproduce the results.

Section I is devoted to 'bottom up' approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour.

Section II covers 'top down' techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers' and modified Hummers' methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach.

The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step.

Sections IV–VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning.

Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V.

Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer.

There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown.

Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp 2 basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp 2 carbon network by π–π stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs, can be functionalized and we summarize emerging approaches to covalently and noncovalently functionalize MoS2 both in the liquid and on substrate.

Section IX describes some of the most popular characterization techniques, ranging from optical detection to the measurement of the electronic structure. Microscopies play an important role, although macroscopic techniques are also used for the measurement of the properties of these materials and their devices. Raman spectroscopy is paramount for GRMs, while PL is more adequate for non-graphene LMs (see section IX.2). Liquid based methods result in flakes with different thicknesses and dimensions. The qualification of size and thickness can be achieved using imaging techniques, like scanning probe microscopy (SPM) or transmission electron microscopy (TEM) or spectroscopic techniques. Optical microscopy enables the detection of flakes on suitable surfaces as well as the measurement of optical properties. Characterization of exfoliated materials is essential to improve the GRM metrology for applications and quality control. For grown GRMs, SPM can be used to probe morphological properties, as well as to study growth mechanisms and quality of transfer. More generally, SPM combined with smart measurement protocols in various modes allows one to get obtain information on mechanical properties, surface potential, work functions, electrical properties, or effectiveness of functionalization. Some of the techniques described are suitable for 'in situ' characterization, and can be hosted within the growth chambers. If the diagnosis is made 'ex situ', consideration should be given to the preparation of the samples to avoid contamination. Occasionally cleaning methods have to be used prior to measurement.
},
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pubstate = {published},
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}

@article{Pakulski2020,
title = {Atom‐Thick Membranes for Water Purification and Blue Energy Harvesting},
author = {D. Pakulski and W. Czepa and S. Del Buffa and A. Ciesielski and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adfm.201902394},
year = {2020},
date = {2020-01-10},
journal = {Adv. Funct. Mater.},
volume = {30},
pages = {1902394},
abstract = {Membrane‐based processes, namely, water purification and harvesting of osmotic power deriving from the difference in salinity between seawater and freshwater are two strategic research fields holding great promise for overcoming critical global issues such as the world growing energy demand, climate change, and access to clean water. Ultrathin membranes based on 2D materials (2DMs) are particularly suitable for highly selective separation of ions and effective generation of blue energy because of their unique physicochemical properties and novel transport mechanisms occurring at the nano‐ and sub‐nanometer length scale. However, due to the relatively high costs of fabrication compared to traditional porous membrane materials, their technological transfer toward large‐scale applications still remains a great challenge. Herein, the authors present an overview of the current state‐of‐the‐art in the development of ultrathin membranes based on 2DMs for osmotic power generation and water purification. The authors discuss several synthetic routes to produce atomically thin membranes with controlled porosity and describe in detail their performance, with a particular emphasis on pressure‐retarded osmosis and reversed electrodialysis methods. In the last section, an outlook and current limitations as well as viable future developments in the field of 2DM membranes are provided.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Wang2019b,
title = {Tuning the Optical and Electrical Properties of Few‐Layer Black Phosphorus via Physisorption of Small Solvent Molecules},
author = {Y. Wang and A. Slassi and J. Cornil and D. Beljonne and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/smll.201903432},
year = {2019},
date = {2019-11-20},
journal = {Small},
volume = {15},
pages = {1903432},
abstract = {Black phosphorus (BP) is recently becoming more and more popular among semiconducting 2D materials for (opto)electronic applications. The controlled physisorption of molecules on the BP surface is a viable approach to modulate its optical and electronic properties. Solvents consisting of small molecules are often used for washing 2D materials or as liquid media for their chemical functionalization with larger molecules, disregarding their ability to change the opto‐electronic properties of BP. Herein, it is shown that the opto‐electronic properties of mechanically exfoliated few‐layer BP are altered when physically interacting with common solvents. Significantly, charge transport analysis in field‐effect transistors reveals that physisorbed solvent molecules induce a modulation of the charge carrier density which can be as high as 1012 cm−2 in BP, i.e., comparable to common dopants such as F4‐TCNQ and MoO3. By combining experimental evidences with density functional theory calculations, it is confirmed that BP doping by solvent molecules not only depends on charge transfer, but is also influenced by molecular dipole. The results clearly demonstrate how an exquisite tuning of the opto‐electronic properties of few‐layer BP can be achieved through physisorption of small solvent molecules. Such findings are of interest both for fundamental studies and more technological applications in opto‐electronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Lucas2019,
title = {Covalently linked donor–acceptor dyad for efficient single material organic solar cells},
author = {S. Lucas and T. Leydecker and P. Samorì and E. Mena-Osteritz and P. Bäuerle},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/c9cc07179b},
year = {2019},
date = {2019-11-04},
journal = {Chem. Commun},
volume = {55},
pages = {14202–14205},
abstract = {A novel covalently linked donor–acceptor dyad comprising a dithienopyrrol-based oligomeric donor and a fullerene acceptor was synthesized and characterized. The concomitant effect of favorable optoelectronic properties, energy levels of the frontier orbitals, and ambipolar charge transport enabled the application of the dyad in simplified solution-processed single material organic solar cells reaching a power conversion efficiency of 3.4%.
},
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pubstate = {published},
tppubtype = {article}
}

@article{Samorì2019b,
title = {From Supramolecular Chemistry to Complex Chemical Systems},
author = {P. Samorì and N. Giuseppone},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/chem.201904385},
year = {2019},
date = {2019-09-27},
journal = {Chem. Eur. J},
volume = {25},
pages = {13229–13230},
abstract = {Happy Birthday! In their editorial, Paolo Samorì and Nicolas Giuseppone introduce our Virtual Collection honoring Professor Jean‐Marie Lehn on the occasion of his 80th birthday. This anniversary represents just an excellent excuse to celebrate a most remarkable chemist who has always been far ahead of his time, thanks to a unique combination of scientific visions, creativity, breadth, drive, and dedication.
image

It is our greatest pleasure to introduce this Virtual Collection honoring Professor Jean‐Marie Lehn on the occasion of his 80th birthday. This anniversary represents just an excellent excuse to celebrate a most remarkable chemist who has always been far ahead of his time, thanks to a unique combination of scientific visions, creativity, breadth, drive, and dedication. During the last 55 years, he has shaped his field of research and he has been a major source of inspiration for several generations of researchers in chemistry, and sometimes beyond chemistry. We could not see entire parts of biology and materials science as we see them today without knowing what supramolecular chemistry has taught us. Jean‐Marie Lehn has also been a most successful mentor who trained more than 400 students and collaborators over the years in his laboratory, always with a real human touch in all his interpersonal interactions. Over 100 of them are today professors in the most important universities and research centers worldwide, many others are leaders in industry, and one of them even received the Nobel Prize (see Figure 1).
image
Figure 1
Open in figure viewerPowerPoint

Jean‐Marie Lehn (Nobel Prize 1987) together with the recipients of the 2016 Nobel Prize for Chemistry, Jean‐Pierre Sauvage, Sir Fraser Stoddart, and Ben Feringa, during the Ceremony in Stockholm on December 10th, 2016. Supramolecular chemistry concepts have been instrumental in the design and synthesis of artificial molecular machines. ©Nobel Media AB. Photo: Alexander Mahmoud. The Nobel Foundation is gratefully acknowledged for allowing the publication of this photo.

Jean‐Marie Lehn is in formal records an Alsatian, strongly attached to his roots, but he can also be firmly described as a true European citizen. He has always been a greatest supporter of Europe, and not surprisingly, together with Peter Gölitz, he founded “Chemistry – A European Journal” in 1995. This has been only one of the many joint initiatives he has co‐directed with Wiley‐VCH. He has been Board Chair of Chemistry ‐A European Journal until 2003 and on the International Advisory Board of Angewandte Chemie for over 20 years. He has supported the launch of the open access journal ChemistryOpen, for which he currently serves as Board Chair, and was founding Co‐Chair of the Editorial Advisory Board of ChemBioChem.

Following a PhD in Chemistry at the University of Strasbourg under the supervision of Prof. Guy Ourisson, former President of the French Academy of Sciences, and a Post Doc at Harvard University with legendary Prof. Robert Burns Woodward working on Vitamin B12, Jean‐Marie Lehn has been Professor at the University of Strasbourg since 1966. In 1980, he took the Chair of Chemistry of Molecular Interactions at the Collège de France in Paris and was awarded the Nobel Prize for Chemistry in 1987, together with Charles J. Pedersen and Donald J. Cram.

Jean‐Marie Lehn is a true innovator who opened numerous new fields of research. Whereas chemistry had been historically considered to rely on the use of covalent bonds to generate isolated molecules with intrinsic physical and chemical properties, the major revolution steered by Professor Lehn has been based on the use of noncovalent interactions to create well‐defined multicomponent architectures: this is the essence of supramolecular chemistry. A major strength of his scientific approach has always been to precisely demonstrate with rigorous methodologies and simple examples new notions, and to put these notions in much broader perspectives – often inspired by philosophy and arts – to generate paradigms of deep impact. From early works dedicated to the selective complexation between a single host molecule and a single guest molecule, he rapidly moved to the extension of supramolecular chemistry towards larger supramolecular assemblies and to their emerging functions as self‐assembled systems. In parallel, he demonstrated by a series of striking examples how such entities can be encoded at the molecular level to make their supramolecular structures precisely programmable and reconfigurable, in order to design stimuli‐responsive systems with specific properties and capable of performing well‐defined tasks. A direct consequence of these approaches resulted in his pioneering works in dynamic combinatorial chemistry, a domain merging the reversible nature of supramolecular bonds with combinatorial chemistry, in order to spontaneously generate well‐defined chemical entities from large libraries of constituents. Altogether, this string of endeavors strongly impacted the birth of what we consider nowadays as the chemistry of complex systems, a domain which is of crucial importance to understand very fundamental questions, such as the functioning of living systems, and to drive new technologies in sectors of major societal relevance such as medicine, information technology, and environment. Jean‐Marie Lehn has been overall a real driving force, seeding and catalyzing intellectual advances in fundamental science and processes of innovation in industry: a true gift for chemistry and for science.

This interdisciplinary research was given a home in 2002 when Jean‐Marie Lehn founded the Institut de Science et d′Ingénierie Supramoléculaires (ISIS), a truly cross‐disciplinary institute of the University of Strasbourg and CNRS where chemistry is carried out at its interface with physics and biology, in a unique environment where academic and industrial satellite labs are intertwined.

We are most grateful to Wiley, in particular to Neville Compton, Haymo Ross, Francesca Novara, and Diane Smith for shaping up this virtual issue combining some papers of Jean‐Marie Lehn with some of his former students and close collaborators. Although it represents just the “tip of the iceberg”, it already provides ample evidence of the central and instrumental role played by a unique and extremely inspiring scientist who is key to the past, present, and future of chemistry and certainly beyond! },
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@article{Assies2019,
title = {Dynamic covalent conjugated polymer epitaxy on graphene},
author = {L. Assies and C. Fu and P. Kovaříček and Z. Bastl and K. A. Drogowska and J. Lang and V. L. P. Guerra and P. Samorì and E. Orgiu and D. F. Perepichka and M. Kalbáč},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/c9tc03155c},
year = {2019},
date = {2019-09-16},
journal = {J. Mater. Chem. C},
volume = {7},
pages = {12240–12247},
abstract = {
Hybrid heterostructures formed from ordered molecular layers on two-dimensional materials can have unique properties differing from those of their bulk phases. By employing principles of dynamic covalent chemistry, we have synthesized a series of novel conjugated polyimines that form epitaxial ordered monolayers on graphene. The interplay between molecular physisorption and dynamic polymerization at the solid–liquid interface drives the formation of longer chains at the surface with dramatically higher rates than in solution. The physico-chemical properties of such assemblies at different length scales on graphene were investigated by a combination of experimental techniques. ‘Covalent dynamic epitaxy’ was also found to modulate the properties of both substrate and dynamers such as doping and photoluminescence, respectively.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{deOliveira2019,
title = {Liquid‐Gated Transistors Based on Reduced Graphene Oxide for Flexible and Wearable Electronics},
author = {R. Furlan de Oliveira and P. A. Livio and V. Montes-García and S. Ippolito and M. Eredia and P. Fanjul-Bolado and M. B. González García and S. Casalini and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adfm.201905375},
year = {2019},
date = {2019-09-15},
journal = {Adv. Funct. Mater.},
volume = {29},
pages = {1905375},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Stoeckel2019,
title = {Boosting and Balancing Electron and Hole Mobility in Single- and Bilayer WSe2 Devices via Tailored Molecular Functionalization},
author = {M. A. Stoeckel and M. Gobbi and T. Leydecker and Y. Wang and M. Eredia and S. Bonacchi and R. Verucchi and M. Timpel and M. V. Nardi and E. Orgiu and P. Samorì},
editor = {ACS Publcation},
url = {https://doi.org/10.1021/acsnano.9b05423},
year = {2019},
date = {2019-09-11},
journal = {ACS Nano},
volume = {13},
pages = {11613–11622},
abstract = {WSe2 is a layered ambipolar semiconductor enabling hole and electron transport, which renders it a suitable active component for logic circuitry. However, solid-state devices based on single- and bilayer WSe2 typically exhibit unipolar transport and poor electrical performance when conventional SiO2 dielectric and Au electrodes are used. Here, we show that silane-containing functional molecules form ordered monolayers on the top of the WSe2 surface, thereby boosting its electrical performance in single- and bilayer field-effect transistors. In particular, by employing SiO2 dielectric substrates and top Au electrodes, we measure unipolar mobility as high as μh = 150 cm2 V–1 s–1 and μe = 17.9 cm2 V–1 s–1 in WSe2 single-layer devices when ad hoc molecular monolayers are chosen. Additionally, by asymmetric double-side functionalization with two different molecules, we provide opposite polarity to the top and bottom layer of bilayer WSe2, demonstrating nearly balanced ambipolarity at the bilayer limit. Our results indicate that the controlled functionalization of the two sides of the WSe2 mono- and bilayer flakes with highly ordered molecular monolayers offers the possibility to simultaneously achieve energy level engineering and defect functionalization, representing a path toward deterministic control over charge transport in 2D materials.},
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pubstate = {published},
tppubtype = {article}
}

@article{Hou2019,
title = {Photomodulation of Two-Dimensional Self-Assembly of Azobenzene–Hexa-peri-hexabenzocoronene–Azobenzene Triads},
author = {I. C.-Y. Hou and V. Diez-Cabanes and A. Galanti and M. Valášek and M. Mayor and J. Cornil and A. Narita and P. Samorì and K. Müllen
},
editor = {ACS},
url = {https://doi.org/10.1021/acs.chemmater.9b01535},
year = {2019},
date = {2019-09-10},
journal = {Chem. Mater.},
volume = {31},
pages = {6979–6985},
abstract = {Achieving exquisite control over self-assembly of functional polycyclic aromatic hydrocarbons (PAH) and nanographene (NG) is essential for their exploitation as active elements in (nano)technological applications. In the framework of our effort to leverage their functional complexity, we designed and synthesized two hexa-peri-hexabenzocoronene (HBC) triads, pAHA and oAHA, decorated with two light-responsive azobenzene moieties at the pseudo-para and ortho positions, respectively. Their photoisomerization in solution is demonstrated by UV–vis absorption. 1H NMR measurements of oAHA suggested 23% of Z-form can be obtained at a photostationary state with UV irradiation (366 nm). Scanning tunneling microscopy imaging revealed that the self-assembly of pAHA and oAHA at the solid–liquid interface between highly oriented pyrolytic graphite (HOPG) and their solution in 1,2,4-trichlorobenzene can be modulated upon light irradiation. This is in contrast to our previous work using HBC bearing a single azobenzene moiety, which did not show such photomodulation of the self-assembled structure. Upon E-Z isomerization both pAHA and oAHA displayed an increased packing density on the surface of graphite. Moreover, pAHA revealed a change of self-assembled pattern from an oblique unit cell to a dimer row rectangular crystal lattice whereas the assembly of oAHA retained a dimer row structure before and after light irradiation, yet with a modification of the inter-row molecular orientation. Molecular mechanics/molecular dynamics simulations validated the self-assembly patterns of pAHA and oAHA, comprising azobenzenes in their Z-forms. These results pave the way toward use of suitably functionalized large PAHs, as well as NGs, to develop photoswitchable devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Leydecker2019,
title = {Controlling Ambipolar Transport and Voltage Inversion in Solution-Processed Thin-Film Devices through Polymer Blending},
author = {T. Leydecker and M. A. Squillaci and F. Liscio and E. Orgiu and P. Samorì},
editor = {ACS},
url = {https://doi.org/10.1021/acs.chemmater.8b04819},
year = {2019},
date = {2019-09-10},
journal = {Chem. Mater.},
volume = {31},
pages = {6491–6498},
abstract = {Ambipolar semiconductors are attracting a great interest as building blocks for photovoltaics and logic applications. Field-effect transistors built on solution-processable ambipolar materials hold strong promise for the engineering of large-area low-cost logic circuits with a reduced number of devices components. Such devices still suffer from a number of obstacles including the challenging processing, the low Ion/Ioff, the unbalanced mobility, and the low gain in complementary metal–oxide–semiconductor (CMOS)-like circuits. Here, we demonstrate that the simple approach of blending commercially available n- and p-type polymers such as P(NDI2OD-T2), P3HT, PCD-TPT, PDVT-8, and IIDDT-C3 can yield high-performing ambipolar field-effect transistors with balanced mobilities and Ion/Ioff > 107. Each single component was studied separately and upon blending by means of electrical characterization, ambient ultraviolet photoelectron spectroscopy, atomic force microscopy, and grazing incidence wide angle X-ray scattering to unravel the correlation between the morphology/structure of the semiconducting films and their functions. Blends of n- and p-type semiconductors were used to fabricate CMOS-like inverter circuits with state-of-the-art gains over 160 in the case of P(NDI2OD-T2) blended with PDVT-8. Significantly, our blending approach was successful in producing semiconducting films with balanced mobilities for each of the four tested semiconductor blends, although the films displayed different structural and morphological features. Our strategy, which relies on establishing a correlation between ambipolar performances, film morphology, molecular structure, and blending ratio, is extremely efficient and versatile; thus it could be applied to a wide range of polymers or solution processable small molecules.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Mahmood2019,
title = {Tuning graphene transistors through ad hoc electrostatics induced by a nanometer-thick molecular underlayer},
author = {A. Mahmood and C.-S. Yang and S. Jang and L. Routaboul and H. Chang and A. Ghisolfi and P. Braunstein and L. Bernard and T. Verduci and J.-F. Dayen and P. Samorì and J.-O Lee and B. Doudin},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/c9nr06407a},
year = {2019},
date = {2019-09-05},
journal = {Nanoscale},
volume = {11},
pages = {19705–19712},
abstract = {We report on the modulation of the electrical properties of graphene-based transistors that mirror the properties of a few nanometers thick layer made of dipolar molecules sandwiched in between the 2D material and the SiO2 dielectric substrate. The chemical composition of the films of quinonemonoimine zwitterion molecules adsorbed onto SiO2 has been explored by means of X-ray photoemission and mass spectroscopy. Graphene-based devices are then fabricated by transferring the 2D material onto the molecular film, followed by the deposition of top source–drain electrodes. The degree of supramolecular order in disordered films of dipolar molecules was found to be partially improved as a result of the electric field at low temperatures, as revealed by the emergence of hysteresis in the transfer curves of the transistors. The use of molecules from the same family, which are suitably designed to interact with the dielectric surface, results in the disappearance of the hysteresis. DFT calculations confirm that the dressing of the molecules by an external electric field exhibits multiple minimal energy landscapes that explain the thermally stabilized capacitive coupling observed. This study demonstrates that the design and exploitation of ad hoc molecules as an interlayer between a dielectric substrate and graphene represents a powerful tool for tuning the electrical properties of the 2D material. Conversely, graphene can be used as an indicator of the stability of molecular layers, by providing insight into the energetics of ordering of dipolar molecules under the effect of electrical gating.
},
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pubstate = {published},
tppubtype = {article}
}

@article{Mohankumar2019,
title = {Oxacycle‐Fused [1]Benzothieno[3,2‐b][1]benzothiophene Derivatives: Synthesis, Electronic Structure, Electrochemical Properties, Ionisation Potential, and Crystal Structure},
author = {M. Mohankumar and B. Chattopadhyay and R. Hadji and L. Sanguinet and A. R. Kennedy and V. Lemaur and J. Cornil and O. Fenwick and P. Samorì and Y. Geerts},
editor = {Wiley},
url = {https://doi.org/10.1002/cplu.201800346},
year = {2019},
date = {2019-09-02},
journal = {ChemPlusChem},
volume = {84},
pages = {1263–1269},
abstract = {The molecular properties of [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) are vulnerable to structural modifications, which in turn are determined by the functionalization of the backbone. Hence versatile synthetic strategies are needed to discover the properties of this molecule. To address this, we have attempted heteroatom (oxygen) functionalization of BTBT by a concise and easily scalable synthesis. Fourfold hydroxy‐substituted BTBT is the key intermediate, from which the compounds 2,3,7,8‐bis(ethylenedioxy)‐[1]benzothieno[3,2‐b][1]benzothiophene and 2,3,7,8‐bis(methylenedioxy)‐[1]benzothieno[3,2‐b][1]benzothiophene are synthesized. The difference in ether functionalities on the BTBT scaffold influences the ionisation potential values substantially. The crystal structure reveals the transformation of the herringbone motif in bare BTBT towards π‐stacked columns in the newly synthesized derivatives. The results are further justified by the simulated HOMO levels of the model compound...},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Samorì2019b,
title = {π‐Conjugated Molecules: From Structure to Function},
author = {P. Samorì and X. Feng and D. Bonifazi},
editor = {Wiley},
url = {https://doi.org/10.1002/cplu.201900442},
year = {2019},
date = {2019-08-23},
journal = {ChemPlusChem},
volume = {84},
pages = {1177–1178},
abstract = {Appealing properties: ChemPlusChem is proud to present its Special Issue on π‐Conjugated Molecules and their Applications, guest‐edited by Paolo Samorí, Xinliang Feng, and Davide Bonifazi. It contains both research and review articles that feature some of the most enlightening approaches on the synthesis of novel conjugated (macro)molecules, and highlights their special chemical and physical properties arising from the π‐conjugation, as well as their processing and self‐assembly at surfaces and interfaces, and integration into a range of devices.

Since the discovery and development of conductive polymers in the 1970s, which led to the award of the Nobel Prize in Chemistry 2000 to Alan. J. Heeger, Alan. G. MacDiarmid, and Hideki Shirakawa, an ever‐increasing effort is being devoted to the science and technology of π‐conjugated molecules and macromolecules. These systems display unique properties that make them appealing for a multitude of applications in optoelectronics, photonics, energy, and (bio)sensing. Compared to their inorganic counterparts, the greatest advantages of π‐conjugated (macro)molecules lie in the molecular‐level tunability of their optoelectronic properties and their processability into thin films through cheap and easily scalable methods. Furthermore, macromolecular derivatives can feature mechanical properties (flexibility, toughness, malleability, elasticity, etc.) typical of plastics thus making it possible to fabricate nonplanar and even flexible yet robust devices.

The fabrication and technology of plastic optoelectronics is an area of intense international investigation where one of the ultimate goals is to develop smart and multifunctional devices such as LEDs, solar cells, field‐effect transistors, and related applications in flexible active‐matrix electronic‐paper displays, sensing, and radiofrequency identification (RDIF) tags. The knowledge developed in this field will also lead to potential technological breakthroughs in organic nanophotonics, nanoelectronics, spintronics, and data‐storage, as well as novel approaches to smart textiles, medical diagnostic tools (e.g. lab‐on‐a‐chip), biocompatible devices (from artificial retinas to synthetic muscles), and flexible batteries.

At the basis of this interdisciplinary research endeavor, one can find the synthesis of more and more sophisticated 1D, 2D, and 3D (macro)molecular building blocks that are designed to exhibit specific physical and chemical properties. In particular, the synthesis of such systems that possess different structures and dimensionalities, as well as being characterized by multiple and regiospecific substitutions with functional groups at the core, in the scaffold and/or in the periphery, makes it possible to improve fundamental photophysical properties, namely excitation energy and electron transfer. This will allow, among others, tuning of absorption and emission properties, increases in thermal and (photo)chemical stability, enhancement of molar absorptivities and fluorescence quantum efficiencies, and generation of nonlinear optical responses.

It is widely established that the properties of organic and polymeric materials, either arranged as thin or thicker films, strongly depend on the organization at the supramolecular level. This means that the materials and device properties are determined not only by those intrinsic to the structure of the constituent molecules (molecular level) but also by those resulting from the interactions between adjacent molecules (supramolecular level). In particular, there are many physical properties, such as charge transfer (through hopping), charge split and recombination, and exciton diffusion, to name but a few, that depend more critically on the supramolecular organization. In light of this, the self‐assembly and self‐organization of macromolecules at surfaces and interfaces are key, also to enabling optimal interfacial properties such as charge injection and extraction via energy matching. Such a control over these physical properties at the molecular and supramolecular level is therefore of paramount importance for improved device performance.

This Special Issue highlights some of the most enlightening approaches on the synthesis of novel conjugated (macro)molecules with special properties arising from their π‐conjugation, their processing and self‐assembly at surfaces and interfaces, their multiscale analysis of the relevant physical and chemical properties, and their integration in optoelectronic, photovoltaics, batteries, and chemical sensing devices. Images from the Review and Minireview articles, as well as the paper featured on the cover are shown here.

We believe that this Special Issue will offer readers some inspiring examples of the wide scope of this field of science and technology and hopefully convey the enthusiasm of the scientists involved in this research. We are most grateful to all contributing authors for their effort in highlighting and addressing the key questions in this highly dynamic field of chemistry at its interface with physics and engineering, in the interdisciplinary realms of materials and nanoscience.
},
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@article{Pavlica2019,
title = {Enhancement of Charge Transport in Polythiophene Semiconducting Polymer by Blending with Graphene Nanoparticles},
author = {E. Pavlica and N. Pastukhova and R. A. Nawrocki and A. Ciesielski and V. Tkachuk and P. Samorì and G. Bratina},
editor = {Wiley},
url = {https://doi.org/10.1002/cplu.201900219},
year = {2019},
date = {2019-08-21},
journal = {ChemPlusChem},
volume = {84},
pages = {1366–1374},
abstract = {This paper describes a study on the charge transport in a composite of liquid‐exfoliated graphene nanoparticles (GNPs) and a polythiophene semiconducting polymer. While the former component is highly conducting, although it consists of isolated nanostructures, the latter offers an efficient charge transport path between the individual GNPs within the film, overall yielding enhanced charge transport properties of the resulting bi‐component system. The electrical characteristics of the composite layers were investigated by means of measurements of time‐of‐flight photoconductivity and transconductance in field‐effect transistors. In order to analyze both phenomena separately, charge density and charge mobility contributions to the conductivity were singled out. With the increasing GNP concentration, the charge mobility was found to increase, thereby reducing the time spent by the carriers on the polymer chains. In addition, for GNP loading above 0.2 % (wt.), an increase of free charge density was observed that highlights an additional key role played by doping. Variable‐range hopping model of a mixed two‐ and three‐dimensional transport is explained using temperature dependence of mobility and free charge density. The temperature variation of free charge density was related to the electron transfer from polythiophene to GNP, with an energy barrier of 24 meV...},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Squillaci2019,
title = {3D hybrid networks of gold nanoparticles: mechanoresponsive electrical humidity sensors with on-demand performances},
author = {M. A. Squillaci and M.-A. Stoeckel and P. Samorì},
editor = {Royal Society of Chemistry },
url = {https://doi.org/10.1039/c9nr05336k},
year = {2019},
date = {2019-08-15},
journal = {Nanoscale},
volume = {11},
pages = {19319–19326},
abstract = {We have engineered macroscopic 3D porous networks of gold nanoparticles (AuNPs) chemically interconnected by di-thiolated ethylene glycol oligomers. The formation of such superstructures has been followed by means of UV-Vis spectroscopy by monitoring the aggregation-dependent plasmonic band of such nanomaterials. The controlled chemical tethering of the AuNPs with di-thiolated linkers possessing a well-defined contour length rules the interparticle distance. The use of ad-hoc linkers ensures charge transport via direct tunneling and the hygroscopic nature of the ethylene glycol backbone allows interaction with moisture. Upon interaction with water molecules from the atmosphere, our 3D networks undergo swelling reducing the tunnelling current passing through the system. By exploiting such a behavior, we have devised a new approach for the fabrication of electrical resistive humidity sensors. For the first time we have also introduced a new strategy to fabricate stable and robust devices by covalently attaching our 3D networks to gold electrodes. Devices comprising both 4 (TEG) or 6 (HEG) ethylene glycol repetitive units combined with AuNPs exhibited (i) unprecedentedly high response speed (∼26 ms), (ii) short recovery time (∼250 ms) in the absence of any hysteresis effect, and (iii) a linear response to humidity changes characterized by a highest sensitivity of 51 kΩ per RH(%) for HEG- and 500 Ω per RH(%) for TEG-based devices. The employed green solution processing in water and the extreme robustness of our 3D networks make them interesting candidates for the fabrication of sensors which can operate under extreme conditions and for countless cycles.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Wang2019b,
title = {Chemical Synthesis at Surfaces with Atomic Precision: Taming Complexity and Perfection},
author = {C. Wang and L. Chi and A. Ciesielski and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/anie.201906645},
year = {2019},
date = {2019-08-13},
journal = {Angew. Chem. Int. Ed.},
volume = {58},
pages = {18758–18775},
abstract = {canning probe microscopy (SPM) is a powerful tool to study the structure and dynamics of molecules at surfaces and interfaces as well as to precisely manipulate atoms and molecules by applying an external force, by inelastic electron tunneling, or by means of an electric field. The rapid development of these SPM manipulation modes made it possible to achieve fine‐control over fundamental processes in the physics of interfaces as well as chemical reactivity, such as adsorption, diffusion, bond formation, and bond dissociation with precision at the single atom/molecule level. Their controlled use for the fabrication of atomic‐scale structures and synthesis of new, perhaps uncommon, molecules with programmed properties are reviewed. Opportunities and challenges towards the development of complex chemical systems are discussed, by analyzing potential future impacts in nanoscience and nanotechnology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Qiu2019,
title = {Modulating the Charge Transport in 2D Semiconductors via Energy‐Level Phototuning},
author = {H. Qiu and Y. Zhao and Z. Liu and M. Herder and S. Hecht and P. Samorì},
editor = {Wiley},
url = {https://doi.org/10.1002/adma.201903402},
year = {2019},
date = {2019-08-12},
journal = {Adv. Mater.},
volume = {31},
pages = {1903402},
abstract = {The controlled functionalization of semiconducting 2D materials (2DMs) with photoresponsive molecules enables the generation of novel hybrid structures as active components for the fabrication of high‐performance multifunctional field‐effect transistors (FETs) and memories. This study reports the realization of optically switchable FETs by decorating the surface of the semiconducting 2DMs such as WSe2 and black phosphorus with suitably designed diarylethene (DAE) molecules to modulate their electron and hole transport, respectively, without sacrificing their pristine electrical performance. The efficient and reversible photochemical isomerization of the DAEs between the open and the closed isomer, featuring different energy levels, makes it possible to generate photoswitchable charge trapping levels, resulting in the tuning of charge transport through the 2DMs by alternating illumination with UV and visible light. The device reveals excellent data‐retention capacity combined with multiple and well‐distinguished accessible current levels, paving the way for its use as an active element in multilevel memories.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Liu2019,
title = {Water-Dispersed High-Quality Graphene: A Green Solution for Efficient Energy Storage Applications},
author = {Z. Liu and H. Zhang and M. Eredia and H. Qiu and W. Baaziz and O. Ersen and A. Ciesielski and M. Bonn and H. I. Wang and P. Samorì},
editor = {ACS},
url = {https://doi.org/10.1021/acsnano.9b04232},
year = {2019},
date = {2019-08-06},
journal = {ACS Nano},
volume = {13},
pages = {9431–9441},
abstract = {Graphene has been the subject of widespread research during the past decade because of its outstanding physical properties which make it an ideal nanoscale material to investigate fundamental properties. Such characteristics promote graphene as a functional material for the emergence of disruptive technologies. However, to impact daily life products and devices, high-quality graphene needs to be produced in large quantities using an environmentally friendly protocol. In this context, the production of graphene which preserves its outstanding electronic properties using a green chemistry approach remains a key challenge. Herein, we report the efficient production of electrode material for micro-supercapacitors obtained by functionalization of water-dispersed high-quality graphene nanosheets with polydopamine. High-frequency (terahertz) conductivity measurements of the graphene nanosheets reveal high charge carrier mobility up to 1000 cm–2 V–1 s–1. The fine water dispersibility enables versatile functionalization of graphene, as demonstrated by the pseudocapacitive polydopamine coating of graphene nanosheets. The polydopamine functionalization causes a modest, i.e., 20%, reduction of charge carrier mobility. Thin film electrodes based on such hybrid materials for micro-supercapacitors exhibit excellent electrochemical performance, namely a volumetric capacitance of 340 F cm–3 and a power density of 1000 W cm–3, thus outperforming most of the reported graphene-based micro-supercapacitors. These results highlight the potential for water-dispersed, high-quality graphene nanosheets as a platform material for energy-storage applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Squillaci2019b,
title = {2D hybrid networks of gold nanoparticles: mechanoresponsive optical humidity sensors},
author = {M. A. Squillaci and X. Zhong and L. Peyruchat and C. Genet and T. W. Ebbesen and P. Samorì},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/c9nr05337a},
year = {2019},
date = {2019-08-05},
journal = {Nanoscale},
volume = {11},
pages = {19315–19318},
abstract = {Plasmonic coupling is a fascinating phenomenon occurring between neighboring metal nanostructures. We report a straightforward approach to study such process macroscopically by fabricating 2D networks of gold nanoparticles, interconnected with responsive hygroscopic organic linkers. By controlling the humidity we tune the interparticle distance to reversibly trigger plasmonic coupling collectively over several millimeters.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ippolito2019,
title = {Tailoring the physicochemical properties of solution-processed transition metal dichalcogenides via molecular approaches},
author = {S. Ippolito and A. Ciesielski and P. Samorì},
editor = {RSC },
url = {https://doi.org/10.1039/c9cc03845k},
year = {2019},
date = {2019-06-27},
journal = {Chem. Commun},
volume = {55},
pages = {8900–8914},
abstract = {During the last five years, the scientific community has witnessed tremendous progress in solution-processed semiconducting 2D transition metal dichalcogenides (TMDs), in combination with the use of chemical approaches to finely tune their electrical, optical, mechanical and thermal properties. Because of the strong structure–properties relationship, the adopted production methods contribute in affecting the quality and characteristics of the nanomaterials, along with the costs, scalability and yield of the process. Nevertheless, a number of (supra)molecular approaches have been developed to meticulously tailor the properties of TMDs via formation of both covalent and non-covalent bonds, where small molecules, (bio)polymers or nanoparticles interact with the basal plane and/or edges of the 2D nanosheets in a controlled fashion. In this Feature Article, we will highlight the recent advancements in the development of production strategies and molecular approaches for tailoring the properties of solution-processed TMD nanosheets. We will also discuss opportunities and challenges towards the realization of multifunctional devices and sensors based on such novel hybrid nanomaterials.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ruiz-Carretero2019,
title = {Charge transport enhancement in supramolecular oligothiophene assemblies using Pt(II) centers as a guide},
author = {A. Ruiz-Carretero and Y. Atoini and T. Han and A. Operamolla and S. Ippolito and C. Valentini and S. Carrara and S. Sinn and E. A. Prasetyanto and T. Heiser and P. Samorì and G. Farinola and L. De Cola},
editor = {RSC},
url = {https://doi.org/10.1039/c9ta04364k},
year = {2019},
date = {2019-06-20},
journal = {J. Mater. Chem. A},
volume = {7},
pages = {16777–16784},
abstract = {The self-assembly behaviour of platinum(II) neutral complexes has been explored in derivatives exposing oligothiophene substituents in order to organize the semiconducting units in ordered supramolecular structures. The morphology and the photophysical properties of the assemblies were studied by scanning electron microscopy, powder X-ray diffraction and photoluminescence techniques, and correlated to their charge transport properties measured in space-charge-limited current (SCLC) devices. The nature of the intermolecular Pt⋯Pt and/or π–π stacking interactions in the different supramolecular structures and in particular the inter-chromophoric distance were found to affect the hole mobility values estimated for the various semiconducting thiophene-based assemblies. The thiophene-containing architectures exhibit enhanced mobility values compared to the free ligand based ones. These results demonstrate that the supramolecular organization strategy can be applied to generate semiconducting materials via exquisite control over the arrangement of simple conjugated segments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Yao2019,
title = {Unconventional Nanofabrication for Supramolecular Electronics},
author = {Y. Yao and L. Zhang and E. Orgiu and P. Samorì},
editor = {Wiley Online Library },
url = {https://doi.org/10.1002/adma.201900599},
year = {2019},
date = {2019-06-06},
journal = {Advanced Materials},
volume = {31},
number = {1900599},
abstract = {The scientific effort toward achieving a full control over the correlation between structure and function in organic and polymer electronics has prompted the use of supramolecular interactions to drive the formation of highly ordered functional assemblies, which have been integrated into real devices. In the resulting field of supramolecular electronics, self‐assembly of organic semiconducting materials constitutes a powerful tool to generate low‐dimensional and crystalline functional architectures. These include 1D nanostructures (nanoribbons, nanotubes, and nanowires) and 2D molecular crystals with tuneable and unique optical, electronic, and mechanical properties. Optimizing the (opto)electronic properties of organic semiconducting materials is imperative to harness such supramolecular structures as active components for supramolecular electronics. However, their integration in real devices currently represents a significant challenge to the advancement of (opto)electronics. Here, an overview of the unconventional nanofabrication techniques and device configurations to enable supramolecular electronics to become a real technology is provided. A particular focus is put on how single and multiple supramolecular fibers and gels as well as supramolecularly engineered 2D materials can be integrated into novel vertical or horizontal junctions to realize flexible and high‐density multifunctional transistors, photodetectors, and memristors, exhibiting a set of new properties and excelling in their performances.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Witomska2019,
title = {Production and Patterning of Liquid Phase–Exfoliated 2D Sheets for Applications in Optoelectronics},
author = {S. Witomska and T. Leydecker and A. Ciesielski and P. Samorì},
editor = {Wiley Online Library },
url = {https://doi.org/10.1002/adfm.201901126},
year = {2019},
date = {2019-05-31},
journal = {Advanced Functional Materials},
volume = {29},
number = {1901126},
abstract = {2D materials (2DMs), which can be produced by exfoliating bulk crystals of layered materials, display unique optical and electrical properties, making them attractive components for a wide range of technological applications. This review describes the most recent developments in the production of high‐quality 2DMs based inks using liquid‐phase exfoliation (LPE), combined with the patterning approaches, highlighting convenient and effective methods for generating materials and films with controlled thicknesses down to the atomic scale. Different processing strategies that can be employed to deposit the produced inks as patterns and functional thin‐films are introduced, by focusing on those that can be easily translated to the industrial scale such as coating, spraying, and various printing technologies. By providing insight into the multiscale analyses of numerous physical and chemical properties of these functional films and patterns, with a specific focus on their extraordinary electronic characteristics, this review offers the readers crucial information for a profound understanding of the fundamental properties of these patterned surfaces as the millstone toward the generation of novel multifunctional devices. Finally, the challenges and opportunities associated to the 2DMs' integration into working opto‐electronic (nano)devices is discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Galanti2019,
title = {A New Class of Rigid Multi(azobenzene) Switches Featuring Electronic Decoupling: Unravelling the Isomerization in Individual Photochromes},
author = {A. Galanti and J. Santoro and R. Mannancherry and Q. Duez and V. Diez-Cabanes and M. Valášek and J. De Winter and J. Cornil and P. Gerbaux and M. Mayor and P. Samorì},
editor = {American Chemical Society},
url = {https://doi.org/10.1021/jacs.9b02544},
year = {2019},
date = {2019-05-15},
journal = {American Chemical Society},
volume = {141},
pages = {9273−9283},
abstract = {We report a novel class of star-shaped multiazobenzene photoswitches comprising individual photochromes connected to a central trisubstituted 1,3,5-benzene core. The unique design of such C3-symmetric molecules, consisting of conformationally rigid and pseudoplanar scaffolds, made it possible to explore the role of electronic decoupling in the isomerization of the individual azobenzene units. The design of our tris-, bis-, and mono(azobenzene) compounds limits the π-conjugation between the switches belonging to the same molecule, thus enabling the efficient and independent isomerization of each photochrome. An in-depth experimental insight by making use of different complementary techniques such as UV–vis absorption spectroscopy, high performance liquid chromatography, and advanced mass spectrometry methods as ion mobility revealed an almost complete absence of electronic delocalization. Such evidence was further supported by both experimental (electrochemistry, kinetical analysis) and theoretical (DFT calculations) analyses. The electronic decoupling provided by this molecular design guarantees a remarkably efficient photoswitching of all azobenzenes, as evidenced by their photoisomerization quantum yields, as well as by the Z-rich UV photostationary states. Ion mobility mass spectrometry was exploited for the first time to study multiphotochromic compounds revealing the occurrence of a large molecular shape change in such rigid star-shaped azobenzene derivatives. In view of their high structural rigidity and efficient isomerization, our multiazobenzene photoswitches can be used as key components for the fabrication of complex stimuli-responsive porous materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhao2019b,
title = {Functionalization of 2D Materials with Photosensitive Molecules: From Light‐Responsive Hybrid Systems to Multifunctional Devices},
author = {Y. Zhao and S. Ippolito and P. Samorì},
editor = {Wiley},
url = {https://doi.org/10.1002/adom.201900286},
year = {2019},
date = {2019-05-12},
journal = {Advanced Optical Materials},
volume = {7},
pages = {1900286},
abstract = {2D materials possess exceptional physical and chemical properties that render them appealing components for numerous potential applications in (opto)electronics, energy storage, sensing, and biomedicine. However, such unique properties are hardly tunable or modifiable. The functionalization of 2D crystals with molecules constitutes a powerful strategy to adjust and modulate their properties, by also imparting them new functions. In this framework, the combination of 2D materials with photosensitive molecules is a viable route for harnessing their light‐responsive nature. The latter takes full advantage of the extremely high sensitivity of 2D materials to subtle changes in the local environment and the capacity of photosensitive molecules to modify their intrinsic properties when exposed to electromagnetic fields. The hybrid molecule–2D materials can preserve the unique optical and electrical properties of 2D layers and can exhibit additional light‐tunable features. In this Progress Report, the protocols that can be pursued for the 2D material functionalization and switching mechanisms in photosensitive systems are reviewed, followed by an in‐depth discussion on their tunable optical properties and their exploitation when integrated in novel photoswitchable electronic devices. The opportunities and associated challenges to be tackled for the development of unprecedented and high‐performance light‐responsive devices are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Samorì2019,
title = {Interface Engineering in Organic Devices},
author = {P. Samorì and F. Biscarini},
editor = {Wiley Online Library },
url = {https://doi.org/10.1002/admt.201900303},
year = {2019},
date = {2019-05-10},
journal = {Advanced Materials Technologies},
volume = {4},
number = {1900303},
abstract = {Interfaces are ubiquitous in nature and play a key role in many fundamental physical and chemical processes. In organic electronic devices, where charge injection, charge transport, and trapping are indeed interfacial phenomena, the intrinsic properties of the active materials, their processability and their response in devices can be modulated and even disguised by mismatched interfacial properties, sometimes hampering the concept of “properties by molecular design” which is one of the pillars of organic electronics.

Tailoring the interface and thus achieving full control over their properties in fabrication processes of organic devices, and optimizing them for device response, is technologically challenging due to the intertwining of complex phenomena during the assembly of molecular and supramolecular architectures on technological surfaces. Examples include the control of molecular orientation, nucleation and growth of molecularly ordered domains which affect the surface roughness and lateral morphological correlations, as well as the coexistence of misoriented crystalline domains, their size distribution and the extent of domain boundaries. Dynamic processes such as wetting, dewetting and ripening govern the occurrence of (re‐)crystallization yielding the formation of inhomogeneous thin films on specific length scales during the device fabrication, and can also be subjected to re‐adjustment while the device is “in‐action” thereby affecting its time‐stability. From the more functional viewpoint, the boosting of charge injection can be attained via the optimization of energy level alignment and the minimization of energy barriers through the physisorption or chemisorption of suitably designed molecular building blocks. Moreover, density of charged surface states, (local) doping and trapping can be modulated via non‐covalent surface interactions.

The bottom‐up engineering of the physical chemistry of the interfaces is an effective approach towards the multiscale control of supramolecular organization and energy (dis‐)order of the device interfaces, such as organic/dielectric, organic/electrode, organic/organic, and organic/ambient. The approach is also central to the design of chemo‐ and biosensors, as it endows them with sensitivity and selectivity towards specific analytes. Interface engineering has to be regarded, therefore, as an enabling strategy for achieving unprecedented multifunctional and multi‐responsive organic devices with full control over the correlation between structure and function.

This special section of Advanced Materials Technologies reports a few enlightening recent experimental and chemical‐design approaches aimed at controlling and tuning some technologically relevant interfacial properties in organic devices, including field‐effect transistors, solar cells and light‐emitting diodes.

We briefly overview below the five contributions to this special section, sorting them according to a logical sequence, from charge‐injection interfaces, to transport‐layer interfaces, to novel low‐dimensional architectures for organic devices.

Work function modification is the central topic of the article by V. Diez‐Cabanes and co‐workers, as a joint collaboration between Université de Mons (Belgium), ICMAB‐CSIC and CIBER‐BBN Barcelona (Spain), Università di Parma (Italy), and Universidad de Ambato (Ecuador). Self‐assembling monolayers (SAMs) are a vastly explored topic both experimentally and theoretically in organic electronics devices, and SAMs are already consolidated in the manufacturing technology of organic devices. Here the authors report a not‐so well investigated effect, viz. the role of molecular polarizability of SAMs on the work function modification of Au electrodes, and in particular, using a donor‐acceptor paradigmatic dyad, ferrocene (D) and PCTM radical (A), they rationalize the effect of charge transfer and spin states on determining the work function and level alignment at the charge injection interface, also suggesting routes for tailoring the work function shift.

The article by F. Hermerschmidt, S. A. Choulis, and E. J. W. List‐Kratochvil from Humboldt Universität Berlin (Germany) addresses a nowadays relevant technological problem which is the availability, processing and replacement of ITO in conductive transparent electrodes for optoelectronics applications such as OPV and OLED. The authors discuss the potential of the use of metal nanoparticles that are inkjet‐printed, how to process them to control conductivity and interfacial properties, to show how the manufacturing of organic optoelectronics devices can be aligned to a whole‐additive printing platform.

The article by Weining Zhang, Hongliang Chen, and Xuefeng Guo, from Peking University (China) reviews the recent developments and challenges of interface‐engineered organic optoelectronic devices for future applications in electronics and optoelectronics. They emphasize the control of interfacial charge transport for building functional optoelectronic devices, by means of the finest control of individual layers of materials and their interfaces in devices, to design functional transistors, biodetection devices, and flexible electronics, as well as other types of traditional optoelectronic devices, such as photodetectors, photovoltaic devices, and light‐emitting devices, with unprecedented characteristics or unique functionalities.

The group of Yun Li from Nanjing University (China) presents an overview of the technology of field‐effect transistors based on solution‐processed two‐dimensional molecular crystals (2DMCs), as a route to overcome the limits in the charge transport properties imposed by the heterogenous nature of active layers and thin films. They highlight the present capability of upscaled manufacturing of OFETs with 2DMCs, which shows how the field has moved in recent years from the very fundamental field of organic single crystals for studies of the transport physics, towards an enabling technology that may lead to high performance back‐end panels and logic circuits that consumer electronics requires.

The contribution by Zhengbang Wang and Christof Wöll from Karlsruhe Institute of Technology (KIT) (Germany) introduces an emerging class of low‐dimensional nanomaterials, metal‐organic frameworks (MOFs), that are encountering the interest of materials scientists for the next generation of hybrid organic/inorganic optoelectronics, photonics and sensing devices. In particular, the authors discuss the approach to MOFs based on the programmed layer‐by‐layer assembly technique, which enables exquisite control over the MOF architecture on surfaces (SURMOFs) across large areas and with very high control of order and orientation. The relevant properties and device applications are finally reviewed.

This special section well reflects the breadth of this burgeoning and interdisciplinary field of science, which holds great potential for technological breakthroughs. We hope the readers of Advanced Materials Technologies find these contributions inspiring in terms of the importance of devising novel approaches, based on both knowledge and chemical creativity, for the technology of organic devices.

With best regards,

Paolo Samorì & Fabio Biscarini (Guest Editors)
Biographies

Paolo Samorì is Distinguished Professor at the Université de Strasbourg, Director of the Institut de Science et d'Ingénierie Supramoléculaires (ISIS). He obtained a Laurea at University of Bologna and his PhD at the Humboldt University of Berlin. He was permanent research scientist at Istituto per la Sintesi Organica e la Fotoreattività of the Consiglio Nazionale delle Ricerche of Bologna. His research interests encompass nanochemistry, supramolecular sciences, materials chemistry, and scanning probe microscopies with a specific focus on graphene and other 2D materials as well as functional organic/polymeric and hybrid nanomaterials for application in optoelectronics, energy and sensing.
image

Fabio Biscarini is Full Professor of General Chemistry and Nanobiotechnology in the Life Sciences Department, Università di Modena e Reggio Emilia since 2013. From 2017 he is Research Associate at Istituto Italiano di Tecnologia (IIT)‐Center for Translational Neurosciences in Ferrara, where he heads the Organic Neuroelectronics team. He graduated in Industrial Chemistry at Università di Bologna (1986), received a PhD in Chemistry at University of Oregon (1993), and was postdoc (1994–1995) at Consiglio Nazionale delle Ricerche (CNR) Bologna, where became Research Scientist (1994–2000), Senior Scientist (2001–2010), and Research Director (2010–2013). His current research interests are in fundamental aspects of organic bioelectronics, biosensors, and implantable devices for bidirectional communication with the central nervous system.

},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Muchowska2019,
title = {Synthesis and breakdown of universal metabolic precursors promoted by iron},
author = {Kamila B. Muchowska and Sreejith J. Varma and Joseph Moran



},
editor = {Nature},
url = {https://www.nature.com/articles/s41586-019-1151-1},
doi = {10.1038/s41586-019-1151-1},
year = {2019},
date = {2019-05-01},
journal = {Nature},
volume = {569},
pages = {104-107},
abstract = {Life builds its molecules from carbon dioxide (CO2) and breaks them back down again through the intermediacy of just five metabolites, which are the universal hubs of biochemistry1. However, it is unclear how core biological metabolism began and why it uses the intermediates, reactions and pathways that it does. Here we describe a purely chemical reaction network promoted by ferrous iron, in which aqueous pyruvate and glyoxylate—two products of abiotic CO2 reduction2,3,4—build up 9 of the 11 intermediates of the biological Krebs (or tricarboxylic acid) cycle, including all 5 universal metabolic precursors. The intermediates simultaneously break down to CO2 in a life-like regime that resembles biological anabolism and catabolism5. Adding hydroxylamine6,7,8 and metallic iron into the system produces four biological amino acids in a manner that parallels biosynthesis. The observed network overlaps substantially with the Krebs and glyoxylate cycles9,10, and may represent a prebiotic precursor to these core metabolic pathways.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Travaglini2019,
title = {Tuning and controlling the shape of mesoporous silica particles with CTAB/sodium deoxycholate catanionic mixtures},
author = {Travaglini, Leana and Picchetti, Pierre and Del Giudice, Alessandra and Galantini, Luciano and De Cola, Luisa},
editor = {MICROPOROUS AND MESOPOROUS MATERIALS},
doi = {10.1016/j.micromeso.2019.01.030},
year = {2019},
date = {2019-05-01},
journal = {MICROPOROUS AND MESOPOROUS MATERIALS},
volume = {279 },
pages = {423-431},
abstract = {Controlling the shape and size of mesoporous silica particles (MSPs) requires a deep understanding of the different parameters that play a major role during the synthesis of the materials. One of the key factors that can determine the morphology and porosity of the systems is the surfactant, used as a templating agent. We have very recently proven that binary mixtures of hexadecyltrimethylammonium bromide (CTAB) and bile salts are templating systems effective in controlling the morphology of MSPs in a facile and non-costly way. In this work we investigated the effect of different surfactant ratios in order to gain deeper insights on the influence of these catanionic mixtures on particle morphology. We employed mixtures of CTAB and sodium deoxycholate (NaDC) and upon variation of a sole parameter, the NaDC concentration, we achieved shape tuning. Hexagonal platelets, rods, oblate and toroidal particles were obtained and fully characterized. Moreover, investigation of the CTAB/ NaDC assemblies showed that the morphology tuning is related to the evolution of the mixed micelles properties, occurring upon variation of the surfactant ratio.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Aliprandi2019,
title = {Persian waxing of graphite: towards green large-scale production of graphene},
author = {A. Aliprandi and M. Eredia and C. Anichini and W. Baaziz and O. Ersen and A. Ciesielski and P. Samorì},
doi = {10.1039/c9cc01822k},
year = {2019},
date = {2019-04-04},
journal = {Chem. Commun 2019},
volume = {55},
pages = {5331-5334},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Guasch2019,
title = {Two-dimensional self-assembly and electrical properties of the donor-acceptor tetrathiafulvalene-polychlorotriphenylmethyl radical on graphite substrates},
author = {J. Guasch and N. Crivillers and M. Souto and I. Ratera and C. Rovira and P. Samorì and J. Veciana},
editor = {AIP },
url = {https://aip.scitation.org/doi/abs/10.1063/1.5065448},
doi = {10.1063/1.5065448},
year = {2019},
date = {2019-04-02},
journal = {Journal of Applied Physics},
volume = {125},
number = {142909},
abstract = {The electron donor-acceptor tetrathiafulvalene-polychlorotriphenylmethyl (PTM) radical dyad, which shows a strong interplay between intra- and intermolecular charge transfer processes in solution, has been deposited by drop-casting on highly oriented pyrolytic graphite substrates, and its self-assembled structure has been investigated. Conducting atomic force microscopy revealed that the presence of a PTM radical in the molecules enhances the electrical conduction by almost two orders of magnitude and that this enhancement occurs in spite of the poor molecular orientation control achieved with drop-casting. Moreover, the study also reveals that the presence of a tetrathiafulvalene subunit in the deposited molecules can result in slightly asymmetric I-V curves.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhao2019,
title = {A Universal Approach toward Light-Responsive Two-Dimensional Electronics: Chemically Tailored Hybrid van der Waals Heterostructures},
author = {Yuda Zhao and Simone Bertolazzi and Paolo Samorì},
editor = {2019 American Chemical Society},
url = {https://pubs.acs.org/doi/pdf/10.1021/acsnano.9b01716},
doi = {10.1021/acsnano.9b01716},
year = {2019},
date = {2019-03-27},
journal = {ACS Nano 2019},
volume = {13},
number = {4},
pages = {4814-4825},
abstract = {Stimuli-responsive hybrid van der Waals heterostructures (vdWHs), composed of organic molecular switches superimposed on inorganic 2D materials (2DMs), can combine the outstanding physical properties of the latter components with the virtually infinite variety of tunable functionality of molecules, thereby offering an efficient protocol for the development of high-performance multifunctional materials and devices. The use of light as a remote control to modulate the properties of semiconducting 2DMs when interfaced with photochromic molecules suffers from both the limitation associated with the persistent photoconductivity characterizing the 2DMs and the finite thermal stability of the photochromic molecule in its different states. Here, we have devised a universal approach toward the fabrication of optically switchable electronic devices comprising a few nanometers thick azobenzene (AZO) layer physisorbed on 2D semiconductors supported on a trap-free polymer dielectric. The joint effect of the improved 2D/dielectric interface, the molecule’s light-modulated dipolar doping, and the high thermal stability of cis-AZO offers the highest control over the reversible and efficient charge carrier tuning in 2D semiconductors with a preserved high performance in 2D field-effect transistors, as quantified in terms of carrier mobility and Ion/Ioff ratio. The device has the potential to operate as an optical memory with four current levels and long retention time (>15 h). Furthermore, by using a CMOS-compatible micropatterning process, the photoswitchable resistor–diode transition has been achieved on hybrid lateral heterojunction devices. Our approach is of general applicability toward the generation of high-performance hybrid vdWHs for the emergence of functional and responsive devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Darmawan2019,
title = {Blue-emitting bolaamphiphilic zwitterionic iridium(iii) complex},
author = {Darmawan, Noviyan and Sambri, Letizia and Daniliuc, Constantin G. and De Cola, Luisa},
editor = {DALTON TRANSACTIONS},
doi = {10.1039/c8dt04833a},
year = {2019},
date = {2019-03-21},
journal = {DALTON TRANSACTIONS},
volume = {48},
number = {11},
pages = {3664-3670 },
abstract = {Aggregation induced emission is a very interesting phenomenon that recently has attracted a lot of interest. Most of the examples deal with organic molecules or flat metal complexes. Here we demonstrate that, by design, even iridium compounds can display this process without shifting the emission energy. In order to enhance the aggregation properties we have focussed on amphiphilic complexes. We report the synthesis and photophysical characterisation of a blue-emitting bolaamphiphilic zwitterionic Ir(III) complex and an analogous cationic amphiphilic compound, used as a reference. The bolaamphiphile exhibited blue (lambda(max) = 450 nm) emission in dilute, deaerated solution with a photoluminescence quantum yield (PLQY) of 22%, similar to the related cationic amphiphilic complex. The bolaamphiphile displayed significant emission enhancement in the solid state, with an emission quantum yield that reach 52%. Interestingly, the emission of the cationic analogue suffers from aggregation quenching in the solid state, (PLQY = 3%) as is common for these type of complexes. A correlation between the photophysical data and the arrangement in the solid state is discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Hagenmüller2019,
title = {Enhancement of the Electron−Phonon Scattering Induced by Intrinsic Surface Plasmon−Phonon Polaritons},
author = {David Hagenmüller and Johannes Schachenmayer and Cyriaque Genet and Thomas W. Ebbesen and Guido Pupillo},
editor = {Copyright © 2019 American Chemical Society },
doi = {10.1021/acsphotonics.9b00268},
year = {2019},
date = {2019-03-17},
journal = {ACS Photonics 2019, 6 (4), pp 1073–1081},
volume = {6},
number = {4},
pages = {1073-1081},
abstract = {We investigate light−matter coupling in metallic
crystals where plasmons coexist with phonons exhibiting large
oscillator strength. We demonstrate theoretically that this coexistence
can lead to strong light−matter interactions without external
resonators. When the frequencies of plasmons and phonons are
comparable, hybridization of these collective matter modes occurs in
the crystal. We show that the coupling of these modes to photonic
degrees of freedom gives rise to intrinsic surface plasmon−phonon
polaritons, which offer the unique possibility to control the phonon
properties by tuning the electron density and the crystal thickness. In
particular, dressed phonons with reduced frequency and large wave
vectors arise in the case of quasi-2D crystals, which could lead to large
enhancements of the electron−phonon scattering in the vibrational ultrastrong coupling regime. This suggests that photons can
play a key role in determining the quantum properties of certain materials. A nonperturbative self-consistent Hamiltonian
method is presented that is valid for arbitrarily large coupling strengths.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Bertolazzi2019,
title = {Nonvolatile Memories Based on Graphene and Related 2D Materials},
author = {S. Bertolazzi and P. Bondavalli and S. Roche and T. San and S.-Y. Choi and L. Colombo and F. Bonaccorso and P. Samorì},
editor = {Wiley Online Library},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201806663},
doi = {10.1002/adma.201806663},
year = {2019},
date = {2019-03-08},
journal = {Advanced Materials},
volume = {31},
number = {Issue 10},
pages = {1806663},
abstract = {The pervasiveness of information technologies is generating an impressive amount of data, which need to be accessed very quickly. Nonvolatile memories (NVMs) are making inroads into high‐capacity storage to replace hard disk drives, fuelling the expansion of the global storage memory market. As silicon‐based flash memories are approaching their fundamental limit, vertical stacking of multiple memory cell layers, innovative device concepts, and novel materials are being investigated. In this context, emerging 2D materials, such as graphene, transition metal dichalcogenides, and black phosphorous, offer a host of physical and chemical properties, which could both improve existing memory technologies and enable the next generation of low‐cost, flexible, and wearable storage devices. Herein, an overview of graphene and related 2D materials (GRMs) in different types of NVM cells is provided, including resistive random‐access, flash, magnetic and phase‐change memories. The physical and chemical mechanisms underlying the switching of GRM‐based memory devices studied in the last decade are discussed. Although at this stage most of the proof‐of‐concept devices investigated do not compete with state‐of‐the‐art devices, a number of promising technological advancements have emerged. Here, the most relevant material properties and device structures are analyzed, emphasizing opportunities and challenges toward the realization of practical NVM devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Schnoering2019,
title = {Thermally Limited Force Microscopy on Optically Trapped Single Metallic Nanoparticles},
author = {Gabriel Schnoering and Yoseline Rosales-Cabara and Hugo Wendehenne and Antoine Canaguier-Durand and Cyriaque Genet},
editor = {© 2019 American Physical Society},
doi = {DOI: 10.1103/PhysRevApplied.11.034023},
year = {2019},
date = {2019-03-08},
journal = {PHYSICAL REVIEW APPLIED },
volume = {11},
number = { 034023},
abstract = {We propose and evaluate a new type of optical force microscope based on a standing-wave optical trap. Our microscope, calibrated in situ and operating in a dynamic mode, is able to trap, without heating, a single metallic nanoparticle of 150 nm that acts as a highly sensitive probe for external radiation pressure. An Allan-deviation-based stability analysis of the setup yields an optimal 0.1-Hz measurement bandwidth over which the microscope is thermally limited. Over this bandwidth, and with a genuine sine-wave external drive, we demonstrate an optical force resolution down to 3 fN in water at room temperature with a dynamical range for force detection that covers almost 2 orders of magnitude. This resolution is reached in both the confined regime and the freely diffusing regime of the optical trap. In the latter, we measure induced displacements of 10−11 m on the trapped nanoparticle spatially confined within less than 25 nm along the optical axis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{K2019,
title = {Recreating ancient metabolic pathways before enzymes.},
author = {Muchowska K and Chevallot-Beroux E and Moran J},
editor = {Copyright © 2019. Published by Elsevier Ltd},
url = {https://www.sciencedirect.com/science/article/pii/S0968089619300033?via%3Dihub},
doi = {10.1016/j.bmc.2019.03.012},
year = {2019},
date = {2019-03-07},
journal = {Bioorganic & Medicinal Chemistry},
abstract = {The biochemistry of all living organisms uses complex, enzyme-catalyzed metabolic reaction networks. Yet, at life's origins, enzymes had not yet evolved. Therefore, it has been postulated that non-enzymatic metabolic pathways predated their enzymatic counterparts. In this account article, we describe our recent work to evaluate whether two ancient carbon fixation pathways, the rTCA (reductive tricarboxylic acid) cycle and the reductive AcCoA (Wood-Ljungdahl) pathway, could have operated without enzymes and therefore have originated as prebiotic chemistry. We also describe the discovery of an Fe2+-promoted complex reaction network that may represent a prebiotic predecessor to the TCA and glyoxylate cycles. The collective results support the idea that most central metabolic pathways could have roots in prebiotic chemistry.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Krystek2019,
title = {High‐Performance Graphene‐Based Cementitious Composites},
author = {M. Krystek and D. Pakulski and V. Patroniak and M. Górski and L. Szojda and A. Ciesielski and P. Samorì},
editor = {Wiley Online Library },
url = { https://doi.org/10.1002/advs.201801195},
doi = {10.1002/advs.201801195},
year = {2019},
date = {2019-03-07},
journal = {ADVANCED SCIENCE},
volume = {6},
number = {1801195},
abstract = {This study reports on the development of a cementitious composite incorporating electrochemically exfoliated graphene (EEG). This hybrid functional material features significantly enhanced microstructure and mechanical properties, as well as unaffected workability; thus, it outperforms previously reported cementitious composites containing graphene derivatives. The manufacturing of the composite relies on a simple and efficient method that enables the uniform dispersion of EEG within cement matrix in the absence of surfactants. Different from graphene oxide, EEG is found to not agglomerate in cement alkaline environment, thereby not affecting the fluidity of cementitious composites. The addition of 0.05 wt% graphene content to ordinary Portland cement results in an increase up to 79%, 8%, and 9% for the tensile strength, compressive strength, and Young's modulus, respectively. Remarkably, it is found that the addition of EEG promotes the hydration reaction of both alite and belite, thus leading to the formation of a large fraction of 3CaO·2SiO2·3H2O (C‐S‐H) phase. These findings represent a major step forward toward the practical application of nanomaterials in civil engineering.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Hou2019b,
title = {Optically switchable organic light-emitting transistors},
author = {Lili Hou and Xiaoyan Zhang and Giovanni F Cotella and Giuseppe Carnicella and Martin Herder and Bernd M Schmidt and Michael Pätzel and Stefan Hecht andFranco Cacialli and Paolo Samorì },
editor = {Nature},
url = {https://www.nature.com/articles/s41565-019-0370-9},
doi = {10.1038/s41565-019-0370-9},
year = {2019},
date = {2019-02-18},
journal = {Nature Nanotechnology},
volume = {14},
pages = {347-353},
abstract = {Organic light-emitting transistors are pivotal components for emerging opto- and nanoelectronics applications, such as logic circuitries and smart displays. Within this technology sector, the integration of multiple functionalities in a single electronic device remains the key challenge. Here we show optically switchable organic light-emitting transistors fabricated through a judicious combination of light-emitting semiconductors and photochromic molecules. Irradiation of the solution-processed films at selected wavelengths enables the efficient and reversible tuning of charge transport and electroluminescence simultaneously, with a high degree of modulation (on/off ratios up to 500) in the three primary colours. Different emitting patterns can be written and erased through a non-invasive and mask-free process, on a length scale of a few micrometres in a single device, thereby rendering this technology potentially promising for optically gated highly integrated full-colour displays and active optical memory.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Chevallot-Beroux2019,
title = {Synthesis of new Mn19 analogues and their structural, electrochemical and catalytic properties },
author = { Elodie Chevallot-Beroux and Ayuk M. Ako and Wolfgang Schmitt and Brendan Twamley and Joseph Moran and Boudon Corinne and Laurent Ruhlmannc and Samir Mameri},
editor = {Royal Society of Chemistry},
doi = {10.1039/C8DT04807J},
year = {2019},
date = {2019-02-13},
journal = {Dalton Transactions},
number = {15},
abstract = {We report the synthesis and structural characterisation of new Mn19 and Mn18M analogues, [MnIII12MnII7(μ4-O)8(μ3-OCH3)2(μ3-Br)6(HLMe)12(MeOH)6]Br2 (2) and [MnIII12MnII6Sr(μ4-O8(μ3-Cl)8(HLMe)12(MeCN)6]Cl2 cluster (3), where H3LMe is 2,6-bis(hydroxymethyl)-p-cresol. The electrochemistry of 2 and 3 has been investigated and their activity as catalysts in the oxidation of benzyl alcohol has been evaluated. Selective oxidation of benzyl alcohol to benzaldehyde by O2 was achieved using 1 mol% of catalyst with conversions of 74% (2) and 60% (3) at 140 °C using TEMPO as a co-catalyst. No partial conversion of benzaldehyde to benzoic acid was observed. The results obtained revealed that different operative parameters – such as catalyst loading, temperature, time, solvent and the presence of molecular oxygen – played an important role in the selective oxidation of benzyl alcohol.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Thomas2019,
title = {Tilting a ground-state reactivity landscape by vibrational strong coupling},
author = {A. Thomas and L. Lethuillier-Karl and K. Nagarajan, R. M. A. Vergauwe and J. George and T. Chervy and A. Shalabney and E. Devaux and C. Genet and J. Morana nd T. W. Ebbesen},
url = {https://science.sciencemag.org/content/363/6427/615.abstract},
doi = {10.1126/science.aau7742 },
year = {2019},
date = {2019-02-08},
journal = {Science},
volume = {363},
number = {6427},
pages = {615-619},
abstract = {Many chemical methods have been developed to favor a particular product in transformations of compounds that have two or more reactive sites. We explored a different approach to site selectivity using vibrational strong coupling (VSC) between a reactant and the vacuum field of a microfluidic optical cavity. Specifically, we studied the reactivity of a compound bearing two possible silyl bond cleavage sites—Si–C and Si–O, respectively—as a function of VSC of three distinct vibrational modes in the dark. The results show that VSC can indeed tilt the reactivity landscape to favor one product over the other. Thermodynamic parameters reveal the presence of a large activation barrier and substantial changes to the activation entropy, confirming the modified chemical landscape under strong coupling.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Li2019,
title = {Nano-Subsidence-Assisted Precise Integration of Patterned Two-Dimensional Materials for High-Performance Photodetector Arrays},
author = {S.L. Li and L. Zhang and X. Zhong and M. Gobbi and S. Bertolazzi and W. Guo and B. Wu and Y. Liu and N. Xu and W. Niu and Y. Hao and E. Orgiu and P. Samori},
editor = {ASC Publications},
url = {https://pubs.acs.org/doi/10.1021/acsnano.9b00889},
doi = {10.1021/acsnano.9b00889},
year = {2019},
date = {2019-02-07},
journal = {ACS Nano},
volume = {13},
number = {2},
pages = {2654–2662},
abstract = {The spatially precise integration of arrays of micropatterned two-dimensional (2D) crystals onto three-dimensionally structured Si/SiO2 substrates represents an attractive, low-cost system-on-chip strategy toward the realization of extended functions in silicon microelectronics. However, the reliable integration of such atomically thin arrays on planar patterned surfaces has proven challenging due to their poor adhesion to underlying substrates, as ruled by weak van der Waals interactions. Here, we report on an integration method utilizing the flexibility of the atomically thin crystals and their physical subsidence in liquids, which enables the reliable fabrication of the micropatterned 2D materials/Si arrays. Our photodiode devices display peak sensitivity as high as 0.35 A/W and external quantum efficiency (EQE) of ∼90%. The nano-subsidence technique represents a viable path to on-chip integration of 2D crystals onto silicon for advanced microelectronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Pakulski2018,
title = {Novel Keplerate type polyoxometalate-surfactant-graphene hybrids as advanced electrode materials for supercapacitors},
author = {D. Pakulski, A. Gorczyński, W. Czepa, Z. Liu, L. Ortolani, V. Morandi, V. Patroniak, A. Ciesielski, P. Samorì},
editor = {ELSEVIER},
url = {https://doi.org/10.1016/j.ensm.2018.11.012},
year = {2019},
date = {2019-02-01},
journal = {Energy Storage Materials},
volume = {17},
number = {February 2019},
pages = {p 186-193},
abstract = {The development of novel materials for enhanced electrochemical energy storage applications, in particular for the fabrication of supercapacitors (SCs) displaying increased properties, is a milestone of both fundamental and technological relevance. Among nanostructured materials, polyoxometalates (POMs) combined with various carbon-based nanostructures represent a very promising class of hybrid systems for energy storage, yet, guidelines for their rational design and synthesis leading to high-performance SCs is still lacking. Here, we have produced a novel hybrid architecture based on Keplerate type POM (Mo132) functionalized with dodecyltrimethylammonium bromide (DTAB), which upon mixing with electrochemically exfoliated graphene (EEG) nanosheets results in the formation of porous 3D superstructures. Mo132-DTAB-EEG combines the redox activity of POMs and high electrical conductivity of graphene, all synergically mediated by the surfactant-assisted porosity enhancement, to form new electrode materials for SCs. Cyclic voltammetry and galvanostatic charge/discharge electrochemical studies on Mo132-DTAB-EEG performed in aqueous H2SO4 electrolyte revealed that the unique combination of these three components yields highly efficient energy storage materials. In particular, our highly porous hybrids system exhibits high specific capacitance of 65 F g−1 (93 F cm−3, 93mFcm−2) combined with excellent stability (99% of specific capacitance retained) after 5000 charge/discharge cycles at different current densities, overall displaying significantly improved performance compared to pristine electrochemically exfoliated graphene material. Strong non-covalent interactions between Keplerate type polyoxometalate Mo132-DTAB and graphene surface offer higher stability compared to other hybrid POM/carbon-based systems, and unique electrical properties of the multicomponent structure, thereby paving the way towards the development of novel, and potentially multifunctional, POM-based architectures to be exploited as SC electrode materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Lichosyt2019,
title = {Catalytic Transition Metal Systems for Functionalization of Unreactive Sites of Molecules},
author = {Lichosyt, D. and Zhang, Y. and Hurej, K. and Dydio, P.},
editor = {Nature},
url = {https://www.nature.com/articles/s41929-018-0207-1},
year = {2019},
date = {2019-01-29},
journal = {Nature Catalysis},
volume = {2},
pages = {114-122},
abstract = {Catalytic reactions occur readily at the sites of starting materials that are both innately reactive and sterically accessible, or that are predisposed by a functional group amenable to direct a catalyst. However, selective reactions at unbiased sites of substrates remain challenging and typically require additional preactivation steps or the use of highly reactive reagents. Here we report dual-catalytic transition metal systems that merge a reversible activation cycle with a functionalization cycle, which together enable the functionalization of substrates at their inherently unreactive sites. By engaging the Ru- or Fe-catalysed equilibrium between an alcohol and an aldehyde, methods for Pd-catalysed β-arylation of aliphatic alcohols and Rh-catalysed γ-hydroarylation of allylic alcohols were developed. The mild conditions, functional group tolerance and broad scope (81 examples) demonstrate the synthetic applicability of the dual-catalytic systems. This work highlights the potential of the multicatalytic approach to address challenging transformations to circumvent multistep procedures and the use of highly reactive reagents in organic synthesis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Wang2019,
title = {Doping of Monolayer Transition-Metal Dichalcogenides via Physisorption of Aromatic Solvent Molecules},
author = {Ye Wang, Amine Slassi, Marc-Antoine Stoeckel, Simone Bertolazzi, Jerôme Cornil, David Beljonne , Paolo Samorì},
editor = {Copyright © 2019 American Chemical Society },
url = {https://pubs.acs.org/doi/10.1021/acs.jpclett.8b03697},
doi = {10.1021/acs.jpclett.8b03697},
year = {2019},
date = {2019-01-16},
journal = {J. Phys. Chem. Lett},
volume = {10},
number = {3},
pages = {540-547},
abstract = {Two-dimensional (2D) transition-metal dichalcogenides (TMDs) recently emerged as novel materials displaying a wide variety of physicochemical properties that render them unique scaffolds for high-performance (opto)electronics. The controlled physisorption of molecules on the TMD surface is a viable approach for tuning their optical and electronic properties. Solvents, made of small aromatic molecules, are frequently employed for the cleaning of the 2D materials or as a “dispersant” for their chemical functionalization with larger (macro)molecules, without considering their potential key effect in locally modifying the characteristics of 2D materials. In this work, we demonstrate how the electronic and optical properties of a mechanically exfoliated monolayer of MoS2 and WSe2 are modified when physically interacting with small aromatic molecules of common solvents. Low-temperature photoluminescence (PL) spectra recorded at 78 K revealed that physisorbed benzene derivatives could modulate the charge carrier density in monolayer TMDs, hence affecting the switching between a neutral exciton and trion (charged exciton). By combining experimental evidence with density functional theory calculations, we confirm that charge-transfer doping on TMDs depends not only on the difference in chemical potential between molecules and 2D materials but also on the thermodynamic stability of physisorption. Our results provide unambiguous evidences of the great potential of optical and electrical tuning of monolayer MoS2 and WSe2 by physisorption of small aromatic solvent molecules, which is highly relevant for both fundamental studies and device application purposes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}