Vacancy-modulated vertical heterojunction for high-performance self-driven photodetectors

초록

Developing efficient and sustainable ultraviolet (UV) self-powered photodetectors is crucial for next-generation environmental monitoring and wearable optoelectronics. In this work, we proposed a structural strategy for developing self-powered UV photodetectors based on the copper iodide (CuI)/indium‑gallium‑tin-oxide vertical heterojunction, integrated with bottom interlayer and double interlayer (DIL) architectures for controlling vacancy modulation and enhanced charge transport. By introducing interfacial layers and optimizing vacuum annealing conditions, we systematically tuned the copper and iodine vacancy concentrations in CuI thin film, which play critical roles in carrier transport dynamics and device efficiency. Comprehensive characterization confirmed the vacancy modulation mechanisms of effective defect suppression, and structural and surface analyses revealed enhanced crystallinity and film uniformity in vacancy-modulated CuI layers. Furthermore, the optimized heterojunction photodetector with DIL architecture exhibited superior self-powered performance, characterized by high responsivity, reduced ideality factor, increased rectification ratio, and rapid UV photoresponse without external bias. These enhancements are attributed to hydrogen-assisted anion vacancy formation and copper vacancy compensation, enabling efficient charge separation and minimized interfacial recombination. Therefore, this work demonstrates a scalable, low-temperature, and environmentally benign strategy for vacancy engineering in CuI-based optoelectronic systems, offering a viable platform for future self-powered UV photodetectors in energy-autonomous applications.

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