Photomodulation of Charge Transport in All-Semiconducting 2D-1D van der Waals Heterostructures with Suppressed Persistent Photoconductivity Effect.

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.