Layer-Dependent Electron Transfer and Recombination\nProcesses in MoS₂/WSe₂ Multilayer Heterostructures

Abstract

Understanding\nand controlling the charge transfer processes of\ntwo-dimensional (2D) materials are fundamental for the optimized device\nperformance based on 2D semiconductors and heterostructures. The charge\ntransfer rate is very robust in transition metal disulfide (TMD) heterostructures\nwith type II band alignments, which can be manipulated by intercalating\na dielectric layer like hBN to isolate the donor and acceptor monolayers.\nThis study shows that there is an alternative way to change the electron\ntransfer and recombination rates in the case of nLMoS₂/mLWSe₂ multilayer heterostructures, where the donor–acceptor\ndistance is maintained, but the rate of electron transfer is strongly\nlayer dependent and shows asymmetry for the layer number of donor\nand acceptor monolayers. Especially, the 1LMoS₂/2LWSe₂ heterostructure slows electron transfer and charge recombination\nrates ∼2.3 and ∼12 times that of the 1LMoS₂/1LWSe₂ heterostructure, respectively, which have been\ncompetitive with that in the 1LMoS₂/hBN/1LWSe₂ heterostructure. From an application perspective, the noninterfacial\nelectron transfer in which photogenerated electrons should across\nmore than one atomically thin layer is not favorable due to the built-in\nelectric field established by the initial interfacial electron transfer.