Self-Power Broadband Photodetection Enhancement via Co₃O₄/ZnCo₂O₄/ZnO Heterojunction with DFT Analysis

Photodetectors are indispensable optoelectronic devices crucial for various applications such as optical communication, military reconnaissance, multispectral sensing, and environmental surveillance. In this study, we present a photodetector design based on a bottlebrush-like structure comprising Co 3 O 4 /ZnO/ZnO heterojunction, showcasing significant advancements in detection performance. The fabricated photodetector demonstrates a rational band structure, leading to enhanced light absorption efficiency and reduced electron–hole recombination. Notably, it exhibits highly efficient detection capabilities across the ultraviolet–visible–near infrared (UV–vis–NIR) region under zero-bias conduction. By incorporating an intermediate layer of ZnCo 2 O 4, we further enhance the photodetection performance without compromising material morphology. Density functional theory (DFT) analysis elucidates the electronic structure at different heterojunction interfaces, providing insights into electron transitions and their impact on photodetection mechanisms. The combination of DFT results with optical absorption data reveals the underlying principles governing the superior performance of the Co 3 O 4 /ZnCo 2 O 4 /ZnO heterojunction. Our findings demonstrate remarkable metrics for photodetection, with a maximum achievable responsivity ( R ) of 119.99 mA/W and a specific detectivity ( D ) of 2.19 × 10 13 Jones. These results highlight a promising strategy for developing broadband photodetectors based on stable, nontoxic, and cost-effective metal oxides, paving the way for significant advancements in photodetection technology.