Self-Powered Broadband Photodetectors Material Based on Co₃O₄–ZnO Heterojunction with Bottlebrush Nanostructure

Self-powered broadband photodetectors operating in the ultraviolet–visible window are essential for optical communication, military monitoring, multispectral detection, and environmental monitoring. In this study, a new bottlebrush nanostructure based on the Co 3 O 4 –ZnO PN junction is fabricated as an efficient broadband photodetector capable of operation under zero bias conditions. This photodetector has a reasonable band structure, exhibits improved efficiency of light absorption, and features reduced electron–hole recombination. Moreover, the device exhibits highly efficient detection performance in the UV–visible region. The responsivity ( R ), specific detectivity ( D ), and response speed of the device were 22.7 mA W –1, 3.14 × 10 12 Jones, and 20/90 ms, respectively. These results suggest a new strategy for fabricating broadband photodetectors based on stable, nontoxic, low-cost metal oxides.