Photomodulation of transport in monolayer dichalcogenides

Surface functionalization emerges as an alternative pathway for electronic structure engineering in two-dimensional (2D) systems. We explore a hybrid heterostructure built from a 2D transition-metal dichalcogenide atop a layer of photochromic self-assembled azobenzene molecules. This setup can modify carrier transport through the 2D nanosheet by an effective photoactived gating control, achieved through trans to cis isomerization of the azobenzene in close contact with the 2D nanosheet. We show theoretically that this behavior can be ascribed to a tunable gating mechanism. We use a combination of atomistic calculations of the local effective potential profile with simulations of the electron scattering by such potential in a massive Dirac Hamiltonian formalism. We find that different isomers induce a local perturbation with drastically different features that explain well the experimental behavior.