Broad spectral photodetectors based on BiOCl@boronate polymer core-shell heterojunctions

BiOCl has been actively explored as a promising material for photodetectors (PDs), but inefficient charge separation and narrow response spectral range limit the further development of BiOCl-based PDs. Herein, we show that coating BiOCl with a boronate polymer (BP) shell may provide a simple route to overcome the above limitations. The migration of Bi3+ from BiOCl to BP changes the energy level and enhances the light absorption of BP shell. Violent coordination at the core-shell interface, as well as Bi3+ migration induces the generation of Bi3+-O center dot-Bi3+ defects. Also, BP shell can reduce the darkcurrent of BiOCl@BPs PDs. The optimized PD assembled with BiOCl@BP1.9 (the subscript represents the shell thickness) shows fast photoresponse (rise time: 32, decay time: 52 ms, respectively), high on/off ratio, and responsivity of 119.77 mu A/W under 365 nm light at 15 V. Moreover, BiOCl@BP PDs exhibit a gradually broadened spectral response range with the increase of BP shell thickness and show much higher photodetection performances. For example, under 940 nm light stimulation, the optimized PD (BiOCl@BP20.1) exhibits a high responsivity of 22.18 mu A/W, 28 times that of BP PD. Our findings may provide a guideline for the design of high-performance PDs based on the precise construction of polymer-inorganic heterostructures.