Optimizing interfacial charge transfer dynamics of t-Se photoelectrodes for boosting self-powered UV–vis photodetection

Tunable charge transfer is vital for designing high-performance optoelectronic devices. It is interesting to explore more feasible strategies for boosting the performance of self-powered photoelectrochemical-type (PEC) photodetectors. In this work, we demonstrated that optimizing the semiconductor/substrate interfacial properties is a powerful approach to regulate the charge transfer of PEC photodetectors for the first time. We fabricated the t-Se/ZnS heterojunctions by the hydrothermal and electrodeposition methods. Self-powered t-Se/ZnS heterojunction-based PEC photodetector exhibits excellent photoresponse from UV to visible light, where ZnS/FTO interfacial built-in electric field inhibits the photogenerated electrons transfer to FTO substrate and promotes more photogenerated electrons participate in the charge transfer process at t-Se/electrolyte interface, leading to the boosted photoresponse. Furthermore, t-Se/ZnS heterojunctions improve the photogenerated carrier separation efficiency. At 0 ​V bias voltage, the responsivity is as high as 155.48 ​mA/W under 365 ​nm irradiation, which is 4.4 times higher than single t-Se devices, outperforming most of the current broadband PEC photodetectors. In addition, the self-powered t-Se/ZnS PEC photodetectors exhibit a fast response time of 5/50 ​ms and good stability. This work provides new insight for tuning the charge transfer of PEC devices and offers more strategies for building high-performance PEC photodetectors.