(Invited) Controlling and Using Optoelectronic Properties of MoS2 and WS2 Monolayers

Abstract

Transition metal dichalcogenides (TMDCs) are an important class of materials because they can be reduced to 2D, where their quantum confined properties are easily manipulated for various applications. MoS2 is one of the most heavily studied TMDCs and is thermodynamically stable in the semiconducting 2H state. However, these monolayers are more catalytically active and have greater electron conductivity in the unstable, metallic (1T/1T’) state. Recently, we have demonstrated how to control the optoelectronic properties of MoS2 monolayers using n-butyl lithium immersion treatments and functional groups, where shorter treatment times heavily n-type dope MoS2 and longer treatment times fully convert the MoS2 from the semiconducting to metallic (1T/1T’) phase. By adding functional groups, the doped/converted MoS2 is stable for up to two weeks. In addition to MoS2, we have also explored how monolayers of semiconducting WS2 can be used as a contactless humidity sensor via photoluminescence. In this presentation, we will discuss the ways in which MoS2 and WS2 can be tuned for various optoelectronic properties.