PbS-Decorated WS₂ Phototransistors with Fast Response

Abstract

Tungsten disulfide (WS₂), as a typical metal dichalcogenides (TMDs), has aroused keen research interests in photodetection. Here, field effect phototransistors (FE_pTs) based on heterojunction between monolayer WS₂ and PbS colloidal quantum dots are demonstrated to show high photoresponsivity (up to ∼14 A/W), wide electric bandwidth (∼396 Hz), and excellent stability. Meanwhile, the devices exhibit fast photoresponse times of ∼153 μs (rise time) and ∼226 μs (fall time) due to the assistance of heterojunction on the transfer of photoexcitons. Therefore, excellent device performances strongly underscore monolayer WS₂–PbS quantum dot as a promising material for future photoelectronic applications