Perovskite-WS(2) Nanosheet Composite Optical Absorbers on Graphene as High-Performance Phototransistors

High-responsivity phototransistors with a structure of perovskite-WS(2) nanosheet composite optical absorber and a reduced graphene oxide (rGO) channel layer is demonstrated via a facile and low-cost solution-processing method. The WS(2) nanosheets are dispersed within the perovskite matrix, forming the perovskite-WS(2) bulk heterojunction (BHJ). The hybrid phototransistor exhibits excellent figures of merit including high photoresponsivity of 678.8 A/W, high specific detectivity of 4.99 × 10(11) Jones, high EQE value of 2.04 × 10(5)% and rapid response to photoswitching. The high photoresponsivity could be attributed to the WS(2) nanosheets induced photo-generated electron-hole separation promotion effects due to the selective electron trapping effects in the WS(2) nanosheets, together with the high carrier mobility of the rGO channel. This work provides a promising platform for constructing high-responsivity photodetectors.