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 Co3O4–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 × 1012 Jones, and 20/90 ms, respectively. These results suggest a new strategy for fabricating broadband photodetectors based on stable, nontoxic, low-cost metal oxides.