Highly Efficient α-FAPbI₃ Perovskite Wafer-Based Photodetectors Enabled by Intramolecular Hydrogen Bonding

The photoactive α-FAPbI₃ perovskite has gained significant attention for near-infrared (NIR) photodetection due to its excellent optoelectronic properties. However, its practical application is limited by challenges such as ion migration, poor phase stability, and high defect density, which impair device performance and long-term stability. In this study, α-FAPbI₃ perovskite wafers were fabricated using a mechanical hot-pressing method, with oxanilide (OANI) molecules introduced to improve both structural stability and optoelectronic characteristics. OANI molecules form hydrogen bonds with FA⁺ and I^- ions, effectively inhibiting ion migration. Upon NIR illumination, OANI forms intramolecular hydrogen bonds (IMHB) that enhance defect passivation and charge transfer. Consequently, the OANI-modified photodetector demonstrates significant improvements in photoresponse and long-term stability. The device exhibits outstanding performance at 815 nm, with an external quantum efficiency (EQE) of 60.00%, a responsivity of 0.39 A W^-1, and an exceptional specific detectivity of 1.59 × 10¹³ Jones under 15 V bias. Furthermore, the device maintains high stability under prolonged operation and high electric fields, making it suitable for long-term use. This work introduces a NIR-induced IMHB approach to regulate defects and charge dynamics in perovskite, offering a promising route for high-performance, stable photodetectors with applications in biomedical imaging, military surveillance, and environmental monitoring.