Improved Photoelectric Performance of UV Photodetector Based on ZnO Nanoparticle-Decorated BiOCl Nanosheet Arrays onto PDMS Substrate: The Heterojunction and Ti₃C₂T_x MXene Conduction Layer

Large-area BiOCl nanosheet arrays grown on Cu substrate are transferred onto the polydimethylsiloxane (PDMS) substrate, while the as-fabricated BiOCl/PDMS photodetector (PD) yields negligible photocurrents under UV light illumination. The introduction of a Ti₃C₂T_x MXene conduction layer at the interface increases both the photocurrent and dark current by 2–3 orders of magnitude. But this PD suffers from a large dark current (6.7 pA), a low on–off ratio (2.4), and a long decay time (6.87 s) under 350 nm light illumination at 5 V. After the deposition of ZnO nanoparticles (NPs), the optimized PD achieves a low dark current of 86 fA, a high on–off ratio of 7996.5, and a short decay time of 0.93 s. Additionally, the elimination of the Ti₃C₂T_x MXene layer causes decreased photocurrent and prolonged decay time. The greatly improved photoresponse and response speed of these PDs are ascribed to the increased light absorption brought by the ZnO NPs, the improved carrier separation promoted by the ZnO–BiOCl heterojunction, and the efficient carrier pathways provided by the Ti₃C₂T_x MXene conduction layers. The construction of heterojunctions and introduction of conduction additives improve the photodetecting performance of these BiOCl-based PDs, promoting their practical applications in the photoelectric devices.