Perovskite-Inspired Lead-Free Ag₂BiI₅ for Self-Powered NIR-Blind Visible Light Photodetection

In recent years, solution-processible semiconductors with perovskite or perovskite-inspired structures have been extensively investigated for optoelectronic applications. In particular, silver-bismuth-halides have been identified as especially promising because of their bulk properties and lack of heavily toxic elements. This study investigates the potential of Ag₂BiI₅ for near-infrared (NIR)-blind visible light photodetection, which is critical to emerging applications (e.g., wearable optoelectronics and the Internet of Things). Self-powered photodetectors were realized and provided a near-constant ≈ 100 mA W^-1 responsivity through the visible, a NIR rejection ratio of > 250, a long-wavelength responsivity onset matching standard colorimetric functions, and a linear photoresponse of > 5 orders of magnitude. The optoelectronic characterization of Ag₂BiI₅ photodetectors additionally revealed consistency with one-center models and the role of the carrier collection distance in self-powered mode. This study provides a positive outlook of Ag₂BiI₅ toward emerging applications on low-cost and low-power NIR-blind visible light photodetector.