PbS-Decorated WS2 Phototransistors with Fast Response

Tungsten disulfide (WS2), as a typical metal dichalcogenides (TMDs), has aroused keen research interests in photodetection. Here, field effect phototransistors (FEpTs) 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.