Molecular chemistry approaches for tuning the properties of two-dimensional transition metal dichalcogenides

Abstract

Two-dimensional (2D) semiconductors, such as ultrathin layers of transition metal dichalcogenides (TMDs), offer a unique combination of electronic, optical and mechanical properties, and hold potential to enable a host of new device applications spanning from flexible/wearable (opto)electronics to energy-harvesting and sensing technologies. A critical requirement for developing practical and reliable electronic devices based on semiconducting TMDs consists in achieving a full control over their charge-carrier polarity and doping. Inconveniently, such a challenging task cannot be accomplished by means of well-established doping techniques (e.g. ion implantation and diffusion), which unavoidably damage the 2D crystals resulting in degraded device performances. Nowadays, a number of alternatives are being investigated, including various (supra)molecular chemistry approaches relying on the combination of 2D semiconductors with electroactive donor/acceptor molecules. As yet, a large variety of molecular systems have been utilized for functionalizing 2D TMDs via both covalent and non-covalent interactions. Such research endeavours enabled not only the tuning of the charge-carrier doping but also the engineering of the optical, electronic, magnetic, thermal and sensing properties of semiconducting TMDs for specific device applications. Here, we will review the most enlightening recent advancements in experimental (supra)molecular chemistry methods for tailoring the properties of atomically-thin TMDs - in the form of substrate-supported or solution-dispersed nanosheets - and we will discuss the opportunities and the challenges towards the realization of novel hybrid materials and devices based on 2D semiconductors and molecular systems.

Photonic nanoarchitectonics with stimuli-responsive 2D materials

“…There are now many reports available describing how to tailor the properties of the nanosheets and parent layered materials by covalent modifications. 48,49,89,90,[102][103][104][105][106] The reactions are as diverse as the different nanosheet compositions and structures and comprise reactions with thiols, including click reactions, electrophiles, such as alkyl iodides and diazonium salts, isocyanates, epoxides and coordination with metal salts. Furthermore, with the recent focus on improving existing strategies and inventing new ones for quantitative nanosheet exfoliation, processing, and assembly, it is likely that scalable, as well as more complex photonic architectures based on 2D materials become readily available, like for example printable nanostructures and systems amenable to roll-to-roll processes.…”

“…40,41 The advantages for creating structural colors based on 2D materials include their tunable 2D morphology, inherent responsiveness to stimuli by swelling, diversity in composition and structure, and existence of methods to tailor and fine-tune their properties. [42][43][44][45][46][47][48][49] However, they remained almost unexplored until recent times due to the limited availability of nanosheets and efficient processing techniques for 2D materials, despite early efforts with 2D materials in thin film interference sensors. 50 With the recent advances in nanosheet processing protocols and tailoring methods, 43,[51][52][53][54] 2D materials made their way into the field of structural colors.…”

Ping‐Pong Energy Transfer in Covalently Linked Porphyrin‐MoS2 Architectures

“…However, the covalent functionalization of MoS 2 has been accomplished. [7] For example, the basal plane of the 1T-MoS 2 polytype has been reacted with organoiodides, [8] while reaction with diazonium salts has been reported for the basal plane modification of 1T [9] as well as 2H-MoS 2 . [10] Herein we adopt the recently developed method based on the addition of 1,2-dithiolanes to S-vacant sites located at the edges of exfoliated 2H-MoS 2 nanosheets.…”

Simultaneous Optical Tuning of Hole and Electron Transport in Ambipolar WSe2 Interfaced with a Bicomponent Photochromic Layer: From High‐Mobility Transistors to Flexible Multilevel Memories

“…[14][15][16] The interfacing with molecular systems possessing tunable structures and functionalities constitutes an efficient and versatile approach to provide different charge carrier doping levels and thus to reversibly modulate the optoelectronic properties of 2DMs. [17,18] For example, it has been demonstrated that photochromic molecules, capable of undergoing reversible isomerization between two different states induced by light stimuli, [19] can serve as optically responsive components when employed to functionalize unipolar 2DMs. [20,21] Importantly, such hybrid structures take full advantage of the ultrahigh sensitivity of 2DMs to any subtle environmental change, [18] which will emerge as an additional molecular-driven photoresponsivity.…”