@article{Sedona2021,
title = {Au(111) Surface Contamination in Ambient Conditions: Unravelling the Dynamics of the Work Function in Air},
author = {N. Turetta And F. Sedona and A. Liscio and M. Sambi and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/admi.202100068},
year = {2021},
date = {2021-05-21},
journal = {Adv. Mater. Interfaces},
volume = {8},
number = {2100068},
abstract = {Gold is an inert noble metal displaying superior chemical stability that renders it a suitable component for the manufacturing of electrodes for various types of devices. Despite being widely employed, the variation of gold surface properties occurring upon the material's exposure to ambient conditions have been often disregarded. While it is well-known that the contamination of a metallic surface can have a dramatic impact on its properties, the process of contamination itself is poorly understood. Changes of the work function by fractions of an electron-volt are commonly observed in gold surfaces that are processed at ambient laboratory conditions, but an exhaustive comprehension and control of this phenomenon are still lacking. Here, a multiscale characterization of Au(111) surfaces aiming to unravel the surface dynamics underlying the air contamination is presented. The visualization of the adventitious carbon contamination on Au(111) surface by atomic force microscopy is key to rationalize the mechanisms of surface reorganization ruling the change of Au work function between 5.25 and 4.75 eV by solely changing the storage conditions. Such a huge variation must be taken into account when optimizing the Au surface for both controlling its fundamental surface and interfacial physical processes, as well as its functional applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Pakulski2021,
title = {High-sorption terpyridine–graphene oxide hybrid for the efficient removal of heavy metal ions from wastewater},
author = {D. Pakulski and A. Gorczyński and D. Marcinkowski and W. Czepa and T. Chudziak and S. Witomska and Y. Nishina and V. Patroniak and A. Ciesielski and Paolo Samorì},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d1nr02255e},
year = {2021},
date = {2021-05-12},
journal = {Nanoscale},
volume = {13},
pages = {10490–10499},
abstract = {Pollution of wastewater with heavy metal-ions represents one of the most severe environmental problems associated with societal development. To overcome this issue, the design of new, highly efficient systems capable of removing such toxic species, hence to purify water, is of paramount importance for public health and environmental protection. In this work, novel sorption hybrid materials were developed to enable high-performance adsorption of heavy metal ions. Towards this end, graphene oxide (GO) exhibiting various C/O ratios has been functionalized with ad hoc receptors, i.e. terpyridine ligands. The maximum adsorption capacity of highly oxidized/terpyridine hybrids towards Ni(II), Zn(II) and Co(II) was achieved at pH = 6 and 25 °C reaching values of 462, 421 and 336 mg g−1, respectively, being the highest reported in the literature for pristine GO and GO-based sorbents. Moreover, the uptake experiments showed that heavy metal ion adsorption on GO–Tpy and GOh–Tpy is strongly dependent on pH in the range from 2 to 10, as a result of the modulation of interactions at the supramolecular level. Moreover, the ionic strength was found to be independent of heavy metal ion adsorption on GO–Tpy and GOh–Tpy. Under ambient conditions, adsorption capacity values increase with the degree of oxidation of GO because dipolar oxygen units can both interact with heavy-metal ions via dipole–dipole and/or ionic interactions and enable bonding of more covalently anchored terpyridine units. Both adsorption isotherms and kinetics studies revealed that the uptake of the heavy metal ions occurs at a monolayer coverage, mostly controlled by the strong surface complexation with the oxygen of GO and nitrogen-containing groups of terpyridine. Furthermore, selectivity of the hybrid was confirmed by selective sorption of the above heavy metal ions from mixtures involving alkali (Na(I), K(I)) and alkaline Earth (Mg(II), Ca(II)) metal ions due to the chelating properties of the terpyridine subunits, as demonstrated with municipal drinking (tap) water samples. Our findings provide unambiguous evidence for the potential of chemical tailoring of GO-based materials with N-heterocyclic ligands as sorbent materials for highly efficient wastewater purification.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Krystek2021,
title = {Electrochemically Exfoliated Graphene for High-Durability Cement Composites},
author = {M. Krystek and D. Pakulski and M. Górski and L. Szojda and A. Ciesielski and P. Samorì},
editor = {ACS Publcation},
url = {https://doi.org/10.1021/acsami.1c04451},
year = {2021},
date = {2021-05-04},
journal = {ACS Appl. Mater. Interfaces},
volume = {13},
pages = {23000–23010},
abstract = {The development of radically new types of corrosion-resistant cement composites is nowadays compulsory in view of the continuous increase of concrete consumption combined with the intrinsically defective nature of concrete. Among various additives being employed in the concrete technology, carbon nanomaterials have emerged as extremely powerful components capable of remarkably enhancing nano- and microstructures as well as properties of cement-based composites. In this study, we demonstrate that cement mortar incorporating electrochemically exfoliated graphene (EEG) exhibits significantly improved fluid transport properties. The addition of 0.05 wt % of EEG to ordinary Portland cement mortar results in the reduction of initial and secondary sorptivity values by 21 and 25%, respectively. This leads to the outstanding resistance of EEG–cement composites to highly corrosive environments, namely, chloride and sulfate solutions. These observations, combined with the previously reported remarkable enhancement of the tensile strength of EEG–cement mortars, represent a major step toward the development of highly durable graphene-based cement composites.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Wang2021,
title = {2D MXene–Molecular Hybrid Additive for High-Performance Ambipolar Polymer Field-Effect Transistors and Logic Gates},
author = {H. Wang and Y. Wang and Z. Ni and N. Turetta and S. M. Gali and H. Peng and Y. Yao and Y. Chen and I. Janica and D. Beljonne and W. Hu and A. Ciesielski and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adma.202008215},
year = {2021},
date = {2021-04-12},
journal = {Adv. Mater.},
volume = {33},
pages = {2008215},
abstract = {MXenes are highly conductive layered materials that are attracting a great interest for high-performance opto-electronics, photonics, and energy applications.. Their non-covalent functionalization with ad hoc molecules enables the production of stable inks of 2D flakes to be processed in thin-films. Here, the formation of stable dispersions via the intercalation of Ti3C2Tx with didecyldimethyl ammonium bromide (DDAB) yielding Ti3C2Tx–DDAB, is demonstrated. Such functionalization modulates the properties of Ti3C2Tx, as evidenced by a 0.47 eV decrease of the work function. It is also shown that DDAB is a powerful n-dopant capable of enhancing electron mobility in conjugated polymers and 2D materials. When Ti3C2Tx–DDAB is blended with poly(diketopyrrolopyrrole-co-selenophene) [(PDPP–Se)], a simultaneous increase by 170% and 152% of the hole and electron field-effect mobilities, respectively, is observed, compared to the neat conjugated polymer, with values reaching 2.0 cm2 V−1 s−1. By exploiting the balanced ambipolar transport of the Ti3C2Tx–DDAB/PDPP–Se hybrid, complementary metal–oxide–semiconductor (CMOS) logic gates are fabricated that display well-centered trip points and good noise margin (64.6% for inverter). The results demonstrate that intercalant engineering represents an efficient strategy to tune the electronic properties of Ti3C2Tx yielding functionalized MXenes for polymer transistors with unprecedented performances and functions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Carroli2021,
title = {Multiresponsive Nonvolatile Memories Based on Optically Switchable Ferroelectric Organic Field‐Effect Transistors},
author = {M. Carroli and A. G. Dixon and M. Herder and E. Pavlica and S. Hecht and G. Bratina and E. Orgiu and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adma.202007965},
year = {2021},
date = {2021-04-07},
journal = {Adv. Mater.},
volume = {33},
number = {2007965},
abstract = {Organic transistors are key elements for flexible, wearable, and biocompatible logic applications. Multiresponsivity is highly sought‐after in organic electronics to enable sophisticated operations and functions. Such a challenge can be pursued by integrating more components in a single device, each one responding to a specific external stimulus. Here, the first multiresponsive organic device based on a photochromic–ferroelectric organic field‐effect transistor, which is capable of operating as nonvolatile memory with 11 bit memory storage capacity in a single device, is reported. The memory elements can be written and erased independently by means of light or an electric field, with accurate control over the readout signal, excellent repeatability, fast response, and high retention time. Such a proof of concept paves the way toward enhanced functional complexity in optoelectronics via the interfacing of multiple components in a single device, in a fully integrated low‐cost technology compatible with flexible substrates.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Stoeckel2021,
title = {Analysis of External and Internal Disorder to Understand Band‐Like Transport in n‐Type Organic Semiconductors},
author = {M.‐A. Stoeckel and Y. Olivier and M. Gobbi and D. Dudenko and V. Lemaur and M. Zbiri and A. A. Y. Guilbert and G. D'Avino and F. Liscio and A. Migliori and L. Ortolani and N. Demitri and X. Jin and Y.‐G. Jeong and A. Liscio and M.‐V. Nardia and L. Pasquali and L. Razzari and D. Beljonne and P. Samorì and E. Orgiu},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adma.202007870},
year = {2021},
date = {2021-04-01},
journal = {Adv. Mater.},
volume = {33},
number = {2007870},
abstract = {Charge transport in organic semiconductors is notoriously extremely sensitive to the presence of disorder, both internal and external (i.e., related to interactions with the dielectric layer), especially for n‐type materials. Internal dynamic disorder stems from large thermal fluctuations both in intermolecular transfer integrals and (molecular) site energies in weakly interacting van der Waals solids and sources transient localization of the charge carriers. The molecular vibrations that drive transient localization typically operate at low‐frequency ( keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Backes2021,
title = {Biomedical applications: general discussion},
author = {C. Backes and R. K. Behera and A. Bianco and C. Casiraghi and H. Doan and A. Criado and F. Galembeck and S. Goldie and A. M. Gravagnuolo and H.-L. Hou and A. R. Kamali and K. Kostarelos and V. Kumar and W. H. Lee and N. Martsinovich and V. Palermo and M. Palma and J. Pang and M. Prato and P. Samorì and A. Silvestri and S. Singh and M. Strano and C. Wetzl},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d1fd90003j},
year = {2021},
date = {2021-03-24},
journal = {Faraday Discuss.},
volume = {227},
pages = {245–258},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Backes2021b,
title = {2D materials production and generation of functional inks: general discussion},
author = {C. Backes and A. Bianco and C. Casiraghi and F. Galembeck and R. K. Gupta and M. C. Hersam and A. R. Kamali and M. Kolíbal and V. Kolosov and V. Kumar and W. H. Lee and N. Martsinovich and M. Melchionna and K. Müllen and A. Oyarzun and V. Palermo and M. Prato and P. Samorì and S. Sampath and A. Silvestri and D. Sirbu and R. Sui and A. Turchanin and C. Wetzl and I. A. Wright and Z. Xia and X. Zhuang},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d1fd90002a},
year = {2021},
date = {2021-03-24},
journal = {Faraday Discuss.},
volume = {227},
pages = {141-162},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Reina2021,
title = {Graphene: A Disruptive Opportunity for COVID‐19 and Future Pandemics?},
author = {G. Reina and D. Iglesias and P. Samorì and A. Bianco},
editor = {Wiley Online Library },
url = {https://doi.org/10.1002/adma.202007847},
year = {2021},
date = {2021-03-11},
journal = {Adv. Mater.},
volume = {33},
number = {2007847},
abstract = {The graphene revolution, which has taken place during the last 15 years, has represented a paradigm shift for science. The extraordinary properties possessed by this unique material have paved the road to a number of applications in materials science, optoelectronics, energy, and sensing. Graphene‐related materials (GRMs) are now produced in large scale and have found niche applications also in the biomedical technologies, defining new standards for drug delivery and biosensing. Such advances position GRMs as novel tools to fight against the current COVID‐19 and future pandemics. In this regard, GRMs can play a major role in sensing, as an active component in antiviral surfaces or in virucidal formulations. Herein, the most promising strategies reported in the literature on the use of GRM‐based materials against the COVID‐19 pandemic and other types of viruses are showcased, with a strong focus on the impact of functionalization, deposition techniques, and integration into devices and surface coatings.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Montes-García2021b,
title = {Harnessing Selectivity and Sensitivity in Ion Sensing via Supramolecular Recognition: A 3D Hybrid Gold Nanoparticle Network Chemiresistor},
author = {V. Montes-García and R. Furlan de Oliveira and Y. Wang andA. Berezin and P. Fanjul-Bolado and M. B. González García and T. M. Hermans and D. Bonifazi and S. Casalini and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adfm.202008554},
year = {2021},
date = {2021-03-03},
journal = {Adv. Funct. Mater.},
volume = {31},
number = {2008554},
abstract = {The monitoring of K+ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K+ sensors are unable to meet the requirements for the development of point‐of‐care (POC) sensors. To tackle this grand‐challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad‐hoc supramolecular receptors for K+, namely dithiomethylene dibenzo‐18‐crown‐6 ether is reported here. A multi‐technique characterization allows optimizing a new protocol for fabricating high‐performing CRs for real‐time monitoring of K+ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10–3 to 10–6 m concentration range; ii) high selectivity to K+ in presence of interfering cations (Na+, Ca2+, and Mg2+); iii) high shelf‐life stability (>45 days); iv) reversibility of K+ binding and release; v) successful device integration into microfluidic systems for real‐time monitoring; vi) fast response and recovery times (<18 s), and v) K+ detection in artificial saliva. All these characteristics make the supramolecular CRs a potential tool for future applications as POC devices, especially for health monitoring where the determination of K+ in saliva is pivotal for the early diagnosis of diseases.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ippolito2021b,
title = {Covalently interconnected transition metal dichalcogenide networks via defect engineering for high-performance electronic devices},
author = {S. Ippolito and A. G. Kelly and R. Furlan de Oliveira and M.-A. Stoeckel and D. Iglesias and A. Roy, C. Downing and Z. Bian, L. Lombardi and Y. A. Samad and V. Nicolosi, A. C. Ferrari and J. N. Coleman and P. Samorì},
editor = {Nature Nanotechnology },
url = {https://doi.org/10.1038/s41565-021-00857-9},
year = {2021},
date = {2021-02-25},
journal = {Nat. Nanotechnol.},
volume = {16},
pages = {592–598},
abstract = {Solution-processed semiconducting transition metal dichalcogenides are at the centre of an ever-increasing research effort in printed (opto)electronics. However, device performance is limited by structural defects resulting from the exfoliation process and poor inter-flake electronic connectivity. Here, we report a new molecular strategy to boost the electrical performance of transition metal dichalcogenide-based devices via the use of dithiolated conjugated molecules, to simultaneously heal sulfur vacancies in solution-processed transition metal disulfides and covalently bridge adjacent flakes, thereby promoting percolation pathways for the charge transport. We achieve a reproducible increase by one order of magnitude in field-effect mobility (µFE), current ratio (ION/IOFF) and switching time (τS) for liquid-gated transistors, reaching 10−2 cm2 V−1 s−1, 104 and 18 ms, respectively. Our functionalization strategy is a universal route to simultaneously enhance the electronic connectivity in transition metal disulfide networks and tailor on demand their physicochemical properties according to the envisioned applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Huang2021,
title = {Highly Sensitive Strain Sensors Based on Molecules–Gold Nanoparticles Networks for High‐Resolution Human Pulse Analysis},
author = {C.-B. Huang and Y. Yao and V. Montes-García and M.-A. Stoeckel and M. Von Holst and A. Ciesielski and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/smll.202007593},
year = {2021},
date = {2021-02-24},
journal = {Small},
volume = {17},
number = {2007593},
abstract = {High‐performance flexible strain sensors are key components for the next generation of wearable health monitoring devices. Here, the authors have fabricated a novel strain sensor based on gold nanoparticles (AuNPs) interconnected by flexible and responsive molecular linkers. The combination of conductive AuNPs (25 nm in diameter) with tetra(ethylene glycol) dithiol (SH‐TEG‐SH) linkers yields a covalent 3D network which can be directly deposited onto prepatterned flexible supports exposing interdigitated Au electrodes. The electrically insulating nature of the linkers effectively defines the tunneling modulated charge transfer through the AuNPs network. When compressive/tensile strain is applied, the molecular linkers adopt a compressed/stretched conformation thus decreasing/increasing the interparticle distance, ultimately yielding an exponential increase/decrease of the tunneling current when voltage is applied. The strain sensor displays state‐of‐the‐art performances including a highly sensitive response to both tensile and compressive strain, as quantified by a high gauge factor (GF≈126) combined with other superior sensing properties like high flexibility, short response time (16.1 ms), and good robustness (>2000 cycles). Finally, the applicability of the device for health monitoring is demonstrated: high‐resolution artery pulse waves are acquired by placing the strain sensor onto the skin allowing the extraction of important physical parameters for human‐health assessment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Richard2021,
title = {Functionalized 4,4′-Bipyridines: Synthesis and 2D Organization on Highly Oriented Pyrolytic Graphite},
author = {J. Richard and J. Joseph and C. Wang and A. Ciesielski and J. Weiss and P. Samorì and V. Mamane and J. A. Wytko},
editor = {ACS Publcation},
url = {https://doi.org/10.1021/acs.joc.0c02708},
year = {2021},
date = {2021-02-04},
journal = {J. Org. Chem.},
volume = {86},
pages = {3356−3366},
abstract = {Commercial 4,4′-bipyridine is a popular scaffold that is primarily employed as a linker in 3D self-assembled architectures such as metallo-organic frameworks or as a connector in 2D networks. The introduction of alkyl substituents on the bipyridine skeleton is instrumental when 4,4′-bipyridines are used as linkers to form 2D self-assembled patterns on surfaces. Here, several synthetic strategies to access 4,4′-bipyridines functionalized at various positions are described. These easily scalable reactions have been used to introduce a range of alkyl substituents at positions 2 and 2′ or 3 and 3′ and at positions 2,2′ and 6,6′ in the case of tetra-functionalization. Scanning tunneling microscopy studies of molecular monolayers physisorbed at the graphite–solution interface revealed different supramolecular patterns whose motifs are primarily dictated by the nature and position of the alkyl chains.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Montes-García2021,
title = {Chemical sensing with Au and Ag nanoparticles},
author = {V. Montes-García and M. A. Squillaci and M. Diez-Castellnou and Q. K. Ong and F. Stellacci and P. Samorì},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d0cs01112f},
year = {2021},
date = {2021-01-21},
journal = {Chem. Soc. Rev.},
volume = {50},
pages = {1269–1304},
abstract = {Noble metal nanoparticles (NPs) are ideal scaffolds for the fabrication of sensing devices because of their high surface-to-volume ratio combined with their unique optical and electrical properties which are extremely sensitive to changes in the environment. Such characteristics guarantee high sensitivity in sensing processes. Metal NPs can be decorated with ad hoc molecular building blocks which can act as receptors of specific analytes. By pursuing this strategy, and by taking full advantage of the specificity of supramolecular recognition events, highly selective sensing devices can be fabricated. Besides, noble metal NPs can also be a pivotal element for the fabrication of chemical nose/tongue sensors to target complex mixtures of analytes. This review highlights the most enlightening strategies developed during the last decade, towards the fabrication of chemical sensors with either optical or electrical readout combining high sensitivity and selectivity, along with fast response and full reversibility, with special attention to approaches that enable efficient environmental and health monitoring.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Kovtun2021,
title = {Multiscale Charge Transport in van der Waals Thin Films: Reduced Graphene Oxide as a Case Study},
author = {A. Kovtun and A. Candini and A. Vianelli and A. Boschi and S. Dell’Elce and M. Gobbi and K. H. Kim and S. Lara Avila ,and P. Samorì and M. Affronte and A. Liscio and V. Palermo},
editor = {ACS Publcation},
url = {https://doi.org/10.1021/acsnano.0c07771},
year = {2021},
date = {2021-01-19},
journal = {ACS Nano},
number = {15},
pages = {2654–2667},
abstract = {Large area van der Waals (vdW) thin films are assembled materials consisting of a network of randomly stacked nanosheets. The multiscale structure and the two-dimensional (2D) nature of the building block mean that interfaces naturally play a crucial role in the charge transport of such thin films. While single or few stacked nanosheets (i.e., vdW heterostructures) have been the subject of intensive works, little is known about how charges travel through multilayered, more disordered networks. Here, we report a comprehensive study of a prototypical system given by networks of randomly stacked reduced graphene oxide 2D nanosheets, whose chemical and geometrical properties can be controlled independently, permitting to explore percolated networks ranging from a single nanosheet to some billions with room-temperature resistivity spanning from 10–5 to 10–1 Ω·m. We systematically observe a clear transition between two different regimes at a critical temperature T*: Efros–Shklovskii variable-range hopping (ES-VRH) below T* and power law behavior above. First, we demonstrate that the two regimes are strongly correlated with each other, both depending on the charge localization length ξ, calculated by the ES-VRH model, which corresponds to the characteristic size of overlapping sp2 domains belonging to different nanosheets. Thus, we propose a microscopic model describing the charge transport as a geometrical phase transition, given by the metal–insulator transition associated with the percolation of quasi-one-dimensional nanofillers with length ξ, showing that the charge transport behavior of the networks is valid for all geometries and defects of the nanosheets, ultimately suggesting a generalized description on vdW and disordered thin films.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Lucas2021,
title = {Molecular Donor–Acceptor Dyads for Efficient Single‐Material Organic Solar Cells},
author = {S. Lucas and J. Kammerer and M. Pfannmöller and R. R. Schröder and Y. He and N. Li and C. J. Brabec and T. Leydecker and P. Samorì and T. Marszalek and W. Pisula and E. Mena-Osteritz and P. Bäuerle},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/solr.202000653},
year = {2021},
date = {2021-01-07},
journal = {Sol. RRL},
volume = {5},
number = {1},
abstract = {Single‐material organic solar cells (SMOSCs) promise several advantages with respect to prospective applications in printed large‐area solar foils. Only one photoactive material has to be processed and the impressive thermal and photochemical long‐term stability of the devices is achieved. Herein, a novel structural design of oligomeric donor–acceptor (D–A) dyads 1–3 is established, in which an oligothiophene donor and fullerene acceptor are covalently linked by a flexible spacer of variable length. Favorable optoelectronic, charge transport, and self‐organization properties of the D–A dyads are the basis for reaching power conversion efficiencies up to 4.26% in SMOSCs. The dependence of photovoltaic and charge transport parameters in these ambipolar semiconductors on the specific molecular structure is investigated before and after post‐treatment by solvent vapor annealing. The inner nanomorphology of the photoactive films of the dyads is analyzed with transmission electron microscopy (TEM) and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS). Combined theoretical calculations result in a lamellar supramolecular order of the dyads with a D–A phase separation smaller than 2 nm. The molecular design and the precise distance between donor and acceptor moieties ensure the fundamental physical processes operative in organic solar cells and provide stabilization of D–A interfaces. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Yakhlifi2021,
title = {Oxidant-dependent antioxidant activity of polydopamine films: The chemistry-morphology interplay},
author = {S. El Yakhlifi and M.-L. Alfieri and Y. Arntz and M. Eredia and A. Ciesielski and P. Samorì and M. d’Ischia and V. Ball},
editor = {Science Direct},
url = {https://doi.org/10.1016/j.colsurfa.2021.126134},
year = {2021},
date = {2021-01-01},
journal = {Colloids Surf. A},
volume = {614},
number = {126134},
abstract = {Polydopamine (PDA) films allow to functionalize almost all materials with a conformal and chemically active coating. These coatings can react with reducible metallic cations and with all kinds of molecules carrying nucleophilic groups. Recently, our team extended PDA chemistry to a vast repertoire of oxidants and to acidic conditions. However, the influence of changes in the method of PDA deposition on the properties of the obtained coatings, in particular the antioxidant properties, have not been sufficiently explored. It is anticipated that the antioxidant properties should depend on the film preparation method. A combination of experimental techniques, atomic force microscopy, cyclic voltammetry and X ray photoelectron spectroscopy are used to relate the antioxidant properties of PDA films to their structural features and to their chemical composition. It is demonstrated that the antioxidant properties of PDA films are not only dependent on the type of the employed oxidant – which can be expected to affect a variable density of oxidizable groups on the surface of PDA - but also on the oxidant film morphology and roughness.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Samorì2020,
title = {Introduction to ‘Chemistry of 2D materials: graphene and beyond'},
author = {P. Samorì and X. Feng andV. Palermo},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d0nr90263b},
year = {2020},
date = {2020-12-10},
journal = {Nanoscale},
volume = {12},
pages = {24309–24310},
abstract = {A graphical abstract is available for this content},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Janica2020,
title = {Effect of temperature and exfoliation time on the properties of chemically exfoliated MoS2 nanosheets},
author = {I. Janica and D. Iglesias and S. Ippolito and A. Ciesielski and P. Samorì},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d0cc06792j},
year = {2020},
date = {2020-11-20},
journal = {Chem. Commun.},
volume = {56},
pages = {15573–15576},
abstract = {A systematic investigation of the experimental conditions for the chemical exfoliation of MoS2 using n-butyllithium as intercalating agent has been carried out to unravel the effect of reaction time and temperature for maximizing the percentage of monolayer thick-flakes and achieve a control over the content of metallic 1T vs. semiconductive 2H phases, thereby tuning the electrical properties of ultrathin MoS2 few-layer thick films.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Yao2020,
title = {Organic photodetectors based on supramolecular nanostructures},
author = {Y. Yao and Y. Chen and H. Wang and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/smm2.1009},
year = {2020},
date = {2020-11-08},
journal = {SmartMat},
volume = {1},
number = {1},
abstract = {Self‐assembly of semiconducting (macro)molecules enables the development of materials with tailored‐made properties which could be used as active components for optoelectronics applications. Supramolecular nanostructures combine the merits of soft matter and crystalline materials: They are flexible yet highly crystalline, and they can be processed with low‐cost solution methods. Photodetectors are devices capable to convert a light input into an electrical signal. To achieve high photoresponse, the photogenerated charge carriers should be transported efficiently through the self‐assembled nanostructures to reach the electrodes; this can be guaranteed via optimal π–electron overlapping between adjacent conjugated molecules. Moreover, because of the high surface‐to‐bulk ratio, supramolecular nanostructures are prone to enhance exciton dissociation. These qualities make supramolecular nanostructures perfect platforms for photoelectric conversion. This review highlights the most enlightening recent strategies developed for the fabrication of high‐performance photodetectors based on supramolecular nanostructures. We introduce the key figure‐of‐merit parameters and working mechanisms of organic photodetectors based on single components and p–n heterojunctions. In particular, we describe new methods to devise unprecedented planar and vertical devices to ultimately realize highly integrated and flexible photodetectors. The incorporation of ordered mesoscopic supramolecular nanostructures into macroscopic optoelectronic devices will offer great promise for the next generation of multifunctional and multiresponsive devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Peng2020,
title = {Synthesis of Robust MOFs@COFs Porous Hybrid Materials via an Aza‐Diels–Alder Reaction: Towards High‐Performance Supercapacitor Materials},
author = {H. Peng and J. Raya and F. Richard and W. Baaziz and O. Ersen and A. Ciesielski and P. Samorì},
editor = {Wiley Online Library },
url = {https://doi.org/10.1002/anie.202008408},
year = {2020},
date = {2020-10-26},
journal = {Angew. Chem. Int. Ed},
volume = {59},
pages = {19602–19609},
abstract = {Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have attracted enormous attention in recent years. Recently, MOF@COF are emerging as hybrid architectures combining the unique features of the individual components to enable the generation of materials displaying novel physicochemical properties. Herein we report an unprecedented use of aza‐Diels–Alder cycloaddition reaction as post‐synthetic modification of MOF@COF‐LZU1, to generate aza‐MOFs@COFs hybrid porous materials with extended π‐delocalization. A a proof‐of‐concept, the obtained aza‐MOFs@COFs is used as electrode in supercapacitors displaying specific capacitance of 20.35 μF cm−2 and high volumetric energy density of 1.16 F cm−3. Our approach of post‐synthetic modification of MOFs@COFs hybrids implement rational design for the synthesis of functional porous materials and expands the plethora of promising application of MOFs@COFs hybrid porous materials in energy storage applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Gobbi2020,
title = {Graphene transistors for real-time monitoring molecular self-assembly dynamics},
author = {M. Gobbi and A. Galanti and M.-A. Stoeckel and B. Zyska and S. Bonacchi and S. Hecht and P. Samorì},
editor = {Nature},
url = {https://www.nature.com/articles/s41467-020-18604-4},
year = {2020},
date = {2020-09-18},
journal = {Nat. Commun},
volume = {11},
number = {4731},
abstract = {Mastering the dynamics of molecular assembly on surfaces enables the engineering of predictable structural motifs to bestow programmable properties upon target substrates. Yet, monitoring self-assembly in real time on technologically relevant interfaces between a substrate and a solution is challenging, due to experimental complexity of disentangling interfacial from bulk phenomena. Here, we show that graphene devices can be used as highly sensitive detectors to read out the dynamics of molecular self-assembly at the solid/liquid interface in-situ. Irradiation of a photochromic molecule is used to trigger the formation of a metastable self-assembled adlayer on graphene and the dynamics of this process are monitored by tracking the current in the device over time. In perspective, the electrical readout in graphene devices is a diagnostic and highly sensitive means to resolve molecular ensemble dynamics occurring down to the nanosecond time scale, thereby providing a practical and powerful tool to investigate molecular self-organization in 2D.
Introduction

Molecular self-assembly on surfaces generates highly ordered 2D structures1,2,3, which are capable to impart desired functions to a substrate4,5. As the imparted functions depend on the arrangement on the molecular scale, scanning probe microscopy techniques have been widely employed to map in the direct space the architectural motifs obtained through self-assembly6,7,8,9,10,11,12. The latter, which is ruled by a complex interplay between intramolecular, intermolecular, and interfacial interactions13 is not completely understood14,15.

Unraveling the dynamics of self-assembly16 could provide higher control over key parameters governing the mechanism of molecular self-organization in 2D, thereby permitting to further engineer molecular functionalization7,17. Scanning tunneling microscopy (STM) imaging enabled to monitor with sub-nanometer spatial resolution the kinetics of nucleation and rearrangements taking place in supramolecular adlayers at solid/liquid interfaces18,19,20,21, including light-responsive assemblies composed of photochromic molecules22,23,24,25,26. However, the information provided by STM is confined at a length scale of a few tens of square nanometers, thus not suitable to describe population dynamics of self-assembly on macroscopic distances, which involves billions of molecules. Moreover, the highest temporal resolution of STM is limited by the ability to record a few tens of frames per second16,27, yielding a temporal resolution of 10–100 ms, or slower (1–10 s) when it comes to visualizing molecular assemblies16.

For this reason, the use of a solely electrical read out to track the ensemble dynamics of molecular self-assembly would be a highly desirable tool to attain ultrafast response and insight into the phenomena governing self-organization in 2D. While electronic devices were employed to monitor in real time single-molecule reactions28 and DNA hybridization29, the dynamics of a complex ensemble process such as the on-surface self-assembly has not been read out by means of an electronic device.

Here, we demonstrate that graphene field-effect devices represent a powerful tool to monitor electrically in an easy and controllable way the complex dynamics of on-surface self-assembly of photochromic molecules. As a proof of principle, we employ a molecule that upon irradiation generates a metastable isomer capable of forming a supramolecular assembly at the graphene/solution interface, thereby introducing a light-controlled field effect on graphene analogous to that of an external gate terminal. Therefore, by measuring the temporal evolution of the electrical current flowing through graphene, we are capable to track the dynamics of formation and desorption of the metastable self-assembled monolayer. Importantly, we demonstrate that the ultrahigh surface sensitivity of graphene permits to disentangle the dynamics of self-assembly at the solid–liquid interface from those of ensemble processes taking place simultaneously in the supernatant solution, such as photoisomerization and thermal relaxation.
Results
Optical characterization of photoisomerization in solution

For this study, we employed the spiropyran (SP) derivative shown in Fig. 1a. The octadecyl side chain promotes self-assembly on graphene by forming crystalline lamellae5. Irradiation with ultraviolet (UV) light at 365 nm triggers the conversion to the ring-open zwitterionic merocyanine (MC) isomer, which is metastable and thermally reverts back to the ring-closed SP isomer30. The photoisomerization is accompanied by a drastic change in the physical properties of the molecule, with the MC isomer being characterized by a stronger molecular dipole moment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Zhao2020b,
title = {Molecular Functionalization of Chemically Active Defects in WSe2 for Enhanced Opto‐Electronics},
author = {Y. Zhao and S. M. Gali and C. Wang and A. Pershin and A. Slassi and D. Beljonne and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adfm.202005045},
year = {2020},
date = {2020-09-06},
journal = {Adv. Funct. Mater.},
volume = {30},
number = {2005045},
abstract = {Structural defects are known to worsen electrical and optical properties of 2D materials. Transition metal dichalcogenides (TMDs) are prone to chalcogen vacancies and molecular functionalization of these vacancies offers a powerful strategy to engineer the crystal structure by healing such defects. This molecular approach can effectively improve physical properties of 2D materials and optimize the performance of 2D electronic devices. While this strategy has been successfully exploited to heal vacancies in sulfides, its viability on selenides based TMDs has not yet been proven. Here, by using thiophenol molecules to functionalize monolayer WSe2 surface containing Se vacancies, it is demonstrated that the defect healing via molecular approach not only improves the performance of WSe2 transistors (> tenfold increase in the current density, the electron mobility, and the Ion/Ioff ratio), but also enhances the photoluminescence properties of monolayer WSe2 flakes (threefold increase of photoluminescence intensity at room temperature). Theoretical calculations elucidate the mechanism of molecular passivation, which originates from the strong interaction between thiol functional group at Se vacancy sites and neighboring tungsten atoms. These results demonstrate that the molecular approach represents a powerful strategy to engineer WSe2 transistors and optimize their optical properties, paving the way toward high‐performance 2D (opto)electronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Anichini2020,
title = {Ultrafast and Highly Sensitive Chemically Functionalized Graphene Oxide-Based Humidity Sensors: Harnessing Device Performances via the Supramolecular Approach},
author = {C. Anichini and A. Aliprandi and S. M. Gali and F. Liscio and V. Morandi and A. Minoia and D. Beljonne and A. Ciesielski and P. Samorì},
editor = {ACS Publcation},
url = {https://doi.org/10.1021/acsami.0c11236},
year = {2020},
date = {2020-09-03},
journal = {ACS Appl. Mater. Interfaces},
volume = {12},
pages = {44017–44025},
abstract = {Humidity sensors have been gaining increasing attention because of their relevance for well-being. To meet the ever-growing demand for new cost-efficient materials with superior performances, graphene oxide (GO)-based relative humidity sensors have emerged recently as low-cost and highly sensitive devices. However, current GO-based sensors suffer from important drawbacks including slow response and recovery, as well as poor stability. Interestingly, reduced GO (rGO) exhibits higher stability, yet accompanied by a lower sensitivity to humidity due to its hydrophobic nature. With the aim of improving the sensing performances of rGO, here we report on a novel generation of humidity sensors based on a simple chemical modification of rGO with hydrophilic moieties, i.e., triethylene glycol chains. Such a hybrid material exhibits an outstandingly improved sensing performance compared to pristine rGO such as high sensitivity (31% increase in electrical resistance when humidity is shifted from 2 to 97%), an ultrafast response (25 ms) and recovery in the subsecond timescale, low hysteresis (1.1%), excellent repeatability and stability, as well as high selectivity toward moisture. Such highest-key-performance indicators demonstrate the full potential of two-dimensional (2D) materials when decorated with suitably designed supramolecular receptors to develop the next generation of chemical sensors of any analyte of interest.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Czepa2020b,
title = {Reduced graphene oxide–silsesquioxane hybrid as a novel supercapacitor electrode},
author = {W. Czepa and S. Witomska and A. Ciesielski and P. Samorì},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d0nr05226d},
year = {2020},
date = {2020-08-12},
journal = {Nanoscale},
volume = {12},
pages = {18733–18741},
abstract = {Supercapacitor energy storage devices recently garnered considerable attention due to their cost-effectiveness, eco-friendly nature, high power density, moderate energy density, and long-term cycling stability. Such figures of merit render supercapacitors unique energy sources to power portable electronic devices. Among various energy storage materials, graphene-related materials have established themselves as ideal electrodes for the development of elite supercapacitors because of their excellent electrical conductivity, high surface area, outstanding mechanical properties combined with the possibility to tailor various physical and chemical properties via chemical functionalization. Increasing the surface area is a powerful strategy to improve the performance of supercapacitors. Here, modified polyhedral oligosilsesquioxane (POSS) is used to improve the electrochemical performance of reduced graphene oxide (rGO) through the enhancement of porosity and the extension of interlayer space between the sheets allowing efficient electrolyte transport. rGO–POSS hybrids exhibited a high specific capacitance of 174 F g−1, power density reaching 2.25 W cm−3, and high energy density of 41.4 mW h cm−3 endowed by the introduction of POSS spacers. Moreover, these electrode materials display excellent durability reaching >98% retention after 5000 cycles.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Lin2020,
title = {Comparative Effects of Graphene and Molybdenum Disulfide on Human Macrophage Toxicity},
author = {H. Lin and D.-K. Ji and M. A. Lucherelli and G. Reina and S. Ippolito and P. Samorì and A. Bianco},
editor = {Wiley },
url = {https://doi.org/10.1002/smll.202002194},
year = {2020},
date = {2020-08-02},
journal = {Small},
volume = {16},
number = {2002194},
abstract = {Graphene and other 2D materials, such as molybdenum disulfide, have been increasingly used in electronics, composites, and biomedicine. In particular, MoS2 and graphene hybrids have attracted a great interest for applications in the biomedical research, therefore stimulating a pertinent investigation on their safety in immune cells like macrophages, which commonly engulf these materials. In this study, M1 and M2 macrophage viability and activation are mainly found to be unaffected by few‐layer graphene (FLG) and MoS2 at doses up to 50 µg mL−1. The uptake of both materials is confirmed by transmission electron microscopy, inductively coupled plasma mass spectrometry, and inductively coupled plasma atomic emission spectroscopy. Notably, both 2D materials increase the secretion of inflammatory cytokines in M1 macrophages. At the highest dose, FLG decreases CD206 expression while MoS2 decreases CD80 expression. CathB and CathL gene expressions are dose‐dependently increased by both materials. Despite a minimal impact on the autophagic pathway, FLG is found to increase the expression of Atg5 and autophagic flux, as observed by Western blotting of LC3‐II, in M1 macrophages. Overall, FLG and MoS2 are of little toxicity in human macrophages even though they are found to trigger cell stress and inflammatory responses.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Wang2020,
title = {Collective Dipole‐Dominated Doping of Monolayer MoS2: Orientation and Magnitude Control via the Supramolecular Approach},
author = {Y. Wang and S. M. Gali and A. Slassi and D. Beljonne and P. Samorì},
editor = {Wiley},
url = {https://doi.org/10.1002/adfm.202002846},
year = {2020},
date = {2020-07-12},
journal = {Adv. Funct. Mater},
volume = {30},
number = {2002846},
abstract = {Molecular doping is a powerful, tuneable, and versatile method to modify the electronic properties of 2D transition metal dichalcogenides (TMDCs). While electron transfer is an isotropic process, dipole‐induced doping is a collective phenomenon in which the orientation of the molecular dipoles interfaced to the 2D material is key to modulate and boost this electronic effect, despite it is not yet demonstrated. A novel method toward the molecular functionalization of monolayer MoS2 relying on the molecular self‐assembly of metal phthalocyanine and the orientation‐controlled coordination chemistry of axial ligands is reported here. It is demonstrated that the subtle variation of position and type of functional groups exposed on the pyridinic ligand, yields a molecular dipole with programed magnitude and orientation which is capable to strongly influence the opto‐electronic properties of monolayer MoS2. In particular, experimental results revealed that both p‐ and n‐type doping can be achieved by modulating the charge carrier density up to 4.8 1012 cm−2. Density functional theory calculations showed that the doping mechanism is primarily resulting from the effect of dipole‐induced doping rather than charge transfer. The strategy to dope TMDCs is a highly modulable and robust, and it enables to enrich the functionality of 2D materials‐based devices for high‐performance applications in optoelectronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Liu2020,
title = {Photomodulation of Charge Transport in All‐Semiconducting 2D–1D van der Waals Heterostructures with Suppressed Persistent Photoconductivity Effect},
author = {Z. Liu and H. Qiu and C. Wang and Z. Chen and B. Zyska and A. Narita and A. Ciesielski and S. Hecht and L. Chi and K. Müllen and P. Samorì},
editor = {Wiley Online Library },
url = {https://doi.org/10.1002/adma.202001268},
year = {2020},
date = {2020-07-02},
journal = {Advanced Materials},
volume = {32},
pages = {2001268},
abstract = {Van der Waals heterostructures (VDWHs), obtained via the controlled assembly of 2D atomically thin crystals, exhibit unique physicochemical properties, rendering them prototypical building blocks to explore new physics and for applications in optoelectronics. As the emerging alternatives to graphene, monolayer transition metal dichalcogenides and bottom‐up synthesized graphene nanoribbons (GNRs) are promising candidates for overcoming the shortcomings of graphene, such as the absence of a bandgap in its electronic structure, which is essential in optoelectronics. Herein, VDWHs comprising GNRs onto monolayer MoS2 are fabricated. Field‐effect transistors (FETs) based on such VDWHs show an efficient suppression of the persistent photoconductivity typical of MoS2, resulting from the interfacial charge transfer process. The MoS2‐GNR FETs exhibit drastically reduced hysteresis and more stable behavior in the transfer characteristics, which is a prerequisite for the further photomodulation of charge transport behavior within the MoS2‐GNR VDWHs. The physisorption of photochromic molecules onto the MoS2‐GNR VDWHs enables reversible light‐driven control over charge transport. In particular, the drain current of the MoS2‐GNR FET can be photomodulated by 52%, without displaying significant fatigue over at least 10 cycles. Moreover, four distinguishable output current levels can be achieved, demonstrating the great potential of MoS2‐GNR VDWHs for multilevel memory devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Kang2020,
title = {2D Porous Polymers with sp2‐Carbon Connections and Sole sp2‐Carbon Skeletons},
author = {J. Kang and S. Huang and K. Jiang and C. Lu and Z. Chen and J. Zhu and C. Yang and A. Ciesielski and F. Qiu and X. Zhuang},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/adfm.202000857},
year = {2020},
date = {2020-07-02},
journal = {Advanced Functional Materials},
volume = {30},
pages = {2000857},
abstract = {2D porous polymers with a planar architecture and high specific surface area have significant applications potential, such as for photocatalysis, electrochemical catalysis, gas storage and separation, and sensing. Such 2D porous polymers have generally been classified as 2D metal–organic frameworks, 2D covalent organic frameworks, graphitic carbon nitride, graphdiyne, and sandwich‐like porous polymer nanosheets. Among these, 2D porous polymers with sp2‐hybridized carbon ( C s p 2 ) bonding are an emerging field of interest. Compared with 2D porous polymers linked by B-O, C=N, or CC bonds, C s p 2 ‐linked 2D porous polymers exhibit extended electron delocalization resulting in unique optical/electrical properties, as well as high chemical/photostability and tunable electrochemical performance. Furthermore, such 2D porous polymers are one of the best precursors for the fabrication of 2D porous carbon materials and carbon skeletons with atomically dispersed transition‐metal active sites. Herein, rational synthetic approaches for 2D porous polymers with C s p 2 bonding are summarized. Their current practical photoelectric applications, including for gas separation, luminescent sensing and imaging, electrodes for batteries and supercapacitors, and photocatalysis are also discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Fenwick2020,
title = {X‐Ray‐Induced Growth Dynamics of Luminescent Silver Clusters in Zeolites},
author = {O. Fenwick and E. Coutiño-Gonzalez and F. Richard and S. Bonacchi and W. Baekelant and D. de Vos and M. B. J. Roeffaers and J. Hofkens and P. Samorì},
editor = {Wiley Online Library},
url = {https://doi.org/10.1002/smll.202002063},
year = {2020},
date = {2020-07-02},
journal = {Small},
volume = {16},
pages = {2002063},
abstract = {Herein, AlKα X‐rays are used to drive the growth of luminescent silver clusters in zeolites. The growth of the silver species is tracked using Auger spectroscopy and fluorescence microscopy, by monitoring the evolution from their ions to luminescent clusters and then metallic, dark nanoparticles. It is shown that the growth rate in different zeolites is determined by the mobility of the silver ions in the framework and that the growth dynamics in calcined samples obeys the Hill–Langmuir equation for noncooperative binding. Comparison of the optical properties of X‐ray‐grown silver clusters with silver clusters formed by standard heat treatment indicates that the latter have a higher specificity toward the formation of luminescent clusters of a specific (small) nuclearity, whereas the former produce a wide distribution of cluster species as well as larger nanoparticles.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ji2020,
title = {Controlled functionalization of carbon nanodots for targeted intracellular production of reactive oxygen species},
author = {D.-K. Ji and G. Reina and S. Guo and M. Eredia and P. Samorì and C. Ménard-Moyon and A. Bianco},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d0nh00300j},
year = {2020},
date = {2020-06-10},
journal = {Nanoscale Horiz.},
volume = {5},
pages = {1240–1249},
abstract = {Controlled intracellular release of exogenous reactive oxygen species (ROS) is an innovative and efficient strategy for cancer treatment. Well-designed materials, which can produce ROS in targeted cells, minimizing side effects, still need to be explored as new generation nanomedicines. Here, red-emissive carbon nanodots (CNDs) with intrinsic theranostic properties are devised, and further modified with folic acid (FA) ligand through a controlled covalent functionalization for targeted cell imaging and intracellular production of ROS. We demonstrated that covalent functionalization is an effective strategy to prevent the aggregation of the dots, leading to superior colloidal stability, enhanced luminescence and ROS generation. Indeed, the functional nanodots possess a deep-red emission and good dispersibility under physiological conditions. Importantly, they show excellent targeting properties and generation of high levels of ROS under 660 nm laser irradiation, leading to efficient cell death. These unique properties enable FA-modified carbon nanodots to act as a multifunctional nanoplatform for simultaneous targeted imaging and efficient photodynamic therapy to induce cancer cell death.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Hou2020,
title = {Engineering Optically Switchable Transistors with Improved Performance by Controlling Interactions of Diarylethenes in Polymer Matrices},
author = {L. Hou and T. Leydecker and X. Zhang and W. Rekab and M. Herder and C. Cendra, S. Hecht and I. McCulloch and A. Salleo and E. Orgiu and P. Samorì},
editor = { American Chemical Society },
url = {https://doi.org/10.1021/jacs.0c02961},
year = {2020},
date = {2020-06-02},
journal = {Journal of the American Chemical Society},
volume = {42},
pages = {11050–11059},
abstract = {The integration of photochromic molecules into semiconducting polymer matrices via blending has recently attracted a great deal of attention, as it provides the means to reversibly modulate the output signal of electronic devices by using light as a remote control. However, the structural and electronic interactions between photochromic molecules and semiconducting polymers are far from being fully understood. Here we perform a comparative investigation by combining two photochromic diarylethene moieties possessing similar energy levels yet different propensity to aggregate with five prototypical polymer semiconductors exhibiting different energy levels and structural order, ranging from amorphous to semicrystalline. Our in-depth photochemical, structural, morphological, and electrical characterization reveals that the photoresponsive behavior of thin-film transistors including polymer/diarylethenes blends as the active layer is governed by a complex interplay between the relative position of the energy levels and the polymer matrix microstructure. By matching the energy levels and optimizing the molecular packing, high-performance optically switchable organic thin-film transistors were fabricated. These findings represent a major step forward in the fabrication of light-responsive organic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Parkula2020,
title = {Harnessing Selectivity and Sensitivity in Electronic Biosensing: A Novel Lab-on-Chip Multigate Organic Transistor},
author = {V. Parkula and M. Berto and C. Diacci and B. Patrahau and M. Di Lauro and A. Kovtun and A. Liscio and M. Sensi and P. Samorì and P. Greco and C. A. Bortolotti and F. Biscarini},
editor = {ACS},
url = {https://doi.org/10.1021/acs.analchem.0c01655},
year = {2020},
date = {2020-06-02},
journal = {Anal. Chem.},
volume = {92},
pages = {9330–9337},
abstract = {Electrolyte gated organic transistors can operate as powerful ultrasensitive biosensors, and efforts are currently devoted to devising strategies for reducing the contribution of hardly avoidable, nonspecific interactions to their response, to ultimately harness selectivity in the detection process. We report a novel lab-on-a-chip device integrating a multigate electrolyte gated organic field-effect transistor (EGOFET) with a 6.5 μL microfluidics set up capable to provide an assessment of both the response reproducibility, by enabling measurement in triplicate, and of the device selectivity through the presence of an internal reference electrode. As proof-of-concept, we demonstrate the efficient operation of our pentacene based EGOFET sensing platform through the quantification of tumor necrosis factor alpha with a detection limit as low as 3 pM. Sensing of inflammatory cytokines, which also include TNFα, is of the outmost importance for monitoring a large number of diseases. The multiplexable organic electronic lab-on-chip provides a statistically solid, reliable, and selective response on microliters sample volumes on the minutes time scale, thus matching the relevant key-performance indicators required in point-of-care diagnostics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@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{Iglesias2020,
title = {Simultaneous non-covalent bi-functionalization of 1T-MoS2 ruled by electrostatic interactions: towards multi-responsive materials},
author = {D. Iglesias and S. Ippolito and A. Ciesielski and P. Samorì},
editor = {Royal Society of Chemistry},
url = {https://doi.org/10.1039/d0cc02371j},
year = {2020},
date = {2020-04-29},
journal = {Chemical Communications},
volume = {56},
pages = {6878–6881},
abstract = {Dual functionalization of chemically exfoliated MoS2 has been achieved by exploiting coulombic interactions among positively charged molecules and the negatively charged 2D flakes. The reversibility and kinetics of the process have been studied by spectroscopic tools. The hybrid material has been transferred to various substrates, yielding multifunctional robust flexible films.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@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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@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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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.
},
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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.},
keywords = {},
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}
}