Bi₂O₃/Bi₂S₃ heterojunction composite preparation and photodetection performance

The Bi₂O₃/Bi₂S₃ heterojunction composite was prepared by thermal polymerization combined with room temperature solution method, and its micromorphology, crystal structure and elemental composition were characterized. The results demonstrate that the Bi₂O₃/Bi₂S₃ heterojunction composite exhibits a bulk morphology, accompanied by the presence of pores and a relatively rough surface. Based on the Bi₂O₃/Bi₂S₃ heterojunction composite, the photodetector was fabricated and its photodetection performance was measured under zero bias voltage. When exposed to ultraviolet (UV) light, the maximum photocurrent (0.32 μA) and response speed (65.65/80.56 ms) of the Bi₂O₃/Bi₂S₃ photodetector are significantly enhanced compared to those of the Bi₂O₃ photodetector. In addition, the device exhibits a wide photodetection band from the UV to the visible (Vis) spectrum, as well as fast and stable self-driven photodetection capability. This is mainly attributed the successful coupling of Bi₂O₃ and Bi₂S₃ with a narrow band gap, resulting in the formation of a heterojunction composite that exhibits a type II band structure. It is noteworthy that the photodetection performance of the device was measured by continuously alternating between blue light on and off for 100 times. This indicates that the Bi₂O₃/Bi₂S₃ photodetector exhibits excellent cycle stability.