Anomalous photoluminescence enhancement and resonance charge transfer in type-II 2D lateral heterostructures

Abstract

Type-II band alignment can realize the efficient charge transfer and separation at the semiconductor heterointerface, which results in photoluminescence (PL) quenching. Recently, several researches demonstrated great enhancement of localized PL at the interface of type-II two-dimensional (2D) heterostructure. However, the dominant physical mechanism of this enhanced PL emission has not been well understood. In this work, we symmetrically study the exciton dynamics of type-II lateral heterostructures of monolayer MoS2 and WS2 at room temperatures. The strong PL enhancement along the one-dimensional (1D) heterointerface is associated with the trion emission of the WS2 shell, while a dramatic PL quenching of neutral exciton is observed on the MoS2 core. The enhanced quantum yield of WS2 trion emission can be explained by charge-transfer-enhanced photoexcited carrier dynamics, which is facilitated by resonance hole transfer from MoS2 side to WS2 side. This work sheds light on the 1D exciton photophysics in lateral heterostructures, which has the potential to lead to new concepts and applications of optoelectronic device.