Abstract

Monolayer tungsten selenide (WSe 2 ) has attracted attention due to its direct bandgap-generated strong light emission and light–matter interaction. Herein, vertical WSe 2 /VOCl bilayer heterojunctions with enhanced PL of WSe 2 were synthesized by the vapor growth method. The morphology, crystal structure, and chemical composition of the WSe 2 /VOCl heterojunctions were systematically investigated, which confirmed the successful formation of the heterojunctions. The PL emission intensity of WSe 2 obtained from the WSe 2 /VOCl heterojunction was about 2.4 times higher than that of the WSe 2 monolayer, demonstrating the high optical quality of the WSe 2 /VOCl heterojunction, which was further confirmed by time-resolved PL measurements. The insulator top VOCl, which was deposited on the surface of the semiconductor bottom WSe 2 as a surface passivation material, reducing the impurities and resulting in an atomically clean surface, successfully enhanced the PL emission of the bottom WSe 2 . This vertical WSe 2 /VOCl bilayer heterojunction with PL enhancement could provide a promising platform for optical devices.