A Self-Powered and Temperature-Sensitive Photodetector Based on VO 2 Films With Reversible Dark Current Polarity

Self-powered photodetectors with low dark current and high sensitivity are highly desirable for advanced optoelectronic applications. Herein, we report a novel temperature-sensitive photodetector based on a CH3NH3PbI3/VO2composite film, which integrates the strong visible-light absorption of perovskite and the reversible metal-insulator transition (MIT) of VO2. Operating under zero bias, the device exhibits excellent self-powered performance, achieving a high responsivity of 538 mAW${}^{\text {-1}}$and a broad spectral response ranging from 450 to800nm. Notably, a unique reversible dark current polarity reversal is observed at temperatures below 306.3 K, where the dark current direction is opposite to that of the photocurrent. Temperature-dependent characterizations reveal enhanced photocurrent dynamics near the phase transition regions of both CH3NH3PbI3and VO2. At 300 K, the device attains a detectivity of$3.2\times 10^{{12}}$Jones and an on–off ratio of 342. This work proposes a novel strategy leveraging the synergistic effect of dual phase-transition materials, realizes a temperature-tunable self-powered mechanism induced by spin-coating-induced perovskite inhomogeneity, and bridges the gap between phase-transition materials and hybrid perovskite systems, paving the way for multifunctional photodetectors in dual-parameter sensing and adaptive optical systems.