Functionalization of 2D Materials with Photosensitive Molecules: From Light‐Responsive Hybrid Systems to Multifunctional Devices

Abstract

2D materials possess exceptional physical and chemical properties that render them appealing components for numerous potential applications in (opto)electronics, energy storage, sensing, and biomedicine. However, such unique properties are hardly tunable or modifiable. The functionalization of 2D crystals with molecules constitutes a powerful strategy to adjust and modulate their properties, by also imparting them new functions. In this framework, the combination of 2D materials with photosensitive molecules is a viable route for harnessing their light‐responsive nature. The latter takes full advantage of the extremely high sensitivity of 2D materials to subtle changes in the local environment and the capacity of photosensitive molecules to modify their intrinsic properties when exposed to electromagnetic fields. The hybrid molecule–2D materials can preserve the unique optical and electrical properties of 2D layers and can exhibit additional light‐tunable features. In this Progress Report, the protocols that can be pursued for the 2D material functionalization and switching mechanisms in photosensitive systems are reviewed, followed by an in‐depth discussion on their tunable optical properties and their exploitation when integrated in novel photoswitchable electronic devices. The opportunities and associated challenges to be tackled for the development of unprecedented and high‐performance light‐responsive devices are discussed.

Molecular Approach to Electrochemically Switchable Monolayer MoS2 Transistors

“…A nice proof of this concept was reported by combining photochromic molecules and 2D materials to form light-switchable hybrid van der Waals (vdW) heterostructures, [11][12][13] which have been successfully exploited as channel materials in FETs to construct stimuli-responsive functional devices, including optically controlled FET, optical memory, and optically tunable p-n diode. [14][15][16] These achievements greatly promote the development of 2D hybrid systems in the field of optoelectronics.…”

Guide to optical spectroscopy of layered semiconductors

“…First, it enables access to intrinsic properties of the layers in a well-controlled environment (between two inert buffer layers). Second, the layered material acts as a probe as we make use of the interaction of the optical excitations with the direct environment to investigate, for example, the magnetization of adjacent layers or detection of molecules in proximity 18 .…”

Modulating the Charge Transport in 2D Semiconductors via Energy‐Level Phototuning

“…In this regard, it is highly appealing to manipulate the electronic properties of 2DMs, by also conferring them new functions, toward emergence of novel applications in optoelectronics and related technologies. In view of the highest sensitivity of 2D materials to subtle changes in the local environment, their functionalization with photosensitive molecules represents a powerful strategy for modifying their intrinsic properties when exposed to electromagnetic fields . The modification of the properties of 2D materials when interacting with molecules can result in doping effects due to either charge transfer processes or interfacial dipoles .…”

“…The modification of the properties of 2D materials when interacting with molecules can result in doping effects due to either charge transfer processes or interfacial dipoles . Recently, in order to go beyond the mere doping effect induced modification, much attention has been given to the combination of 2DMs with molecular building blocks, which could impart reversible and phototunable characteristics . Among various approaches, the use of photochromic molecules as optically responsive components makes it possible to form stable hybrid structures with molecular‐driven photoresponsivity .…”