High-performance self-powered ultraviolet photodetector based on BiOCl/TiO2 heterojunctions: Carrier engineering of TiO2

For low-energy photoelectric devices, it is essential to develop self-powered photodetectors (PDs), because it can work independently, wirelessly and sustainably. The heterojunction PDs based on BiOCl nanoflakes (NFs) and anatase TiO2 film fabricated by the hydrothermal method demonstrate the excellent ultraviolet (UV) photoresponse properties without external power supply. The strong built-in electric field formed at the heterojunction interface and the efficient carrier transmission characteristic of TiO2 film can improve the self-powered performance of PDs. The optimized heterojunction device with TiO2 film grown for 1.75 h exhibits a high photocurrent-to-dark current ratio of 103, responsivity of 0.17 A/W, remarkable detectivity of 1.3 × 1012 Jones, linear dynamic range of 70 dB and fast response speed of 23 ms under 0 V bias and weak UV light irradiation (340 nm, 0.18 mW/cm2). These results demonstrate that the BiOCl/TiO2 heterojunction devices have great application potential in the future UV communications systems.