Polymer–Perovskite Microcrystal Heterojunction for Self‐Powered Optical Sensing and Communication

Abstract The quasiepitaxial polymer‐perovskite interface is a critical enabler for next‐generation optoelectronics, offering opulent features of efficient exciton dissociation and carrier transport. However, interfacial complexities, including energy barriers, poor interface, and defect states, pose significant challenges to scalability and performance. This study maps the nanoscale barrier landscape across the polymer‐perovskite interface, revealing excellent photodetection performance and robust optical communication capacity. A tactical quasiepitaxial growth approach enables the fabrication of a high‐yield inorganic–organic abrupt hybrid heterojunction (HHJ) photodetector by integrating CsPbBr 3 monocrystal with a patterned poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) film. This strategy boosts the fabrication yield from 5% to 38% and exhibits significant autonomous light‐sensing performance, including an ultra‐low dark current of below 10 fA at room temperature, a substantial dark‐to‐light conductivity ratio exceeding 10 6 , a linear dynamic range (LDR) of ≈132.2 dB, and an open‐circuit photovoltage of ≈0.7 V. The critical role of Br − vacancies in governing the photoelectrical behavior of the polymer‐perovskite microcrystal heterojunction (PPMC HJ) device is revealed precisely at the nanoscale using various advanced KPFM techniques. Additionally, a light‐to‐frequency converter demonstrates its advanced sensing capabilities. These findings highlight the importance of precision‐engineered polymer‐perovskite microcrystal heterojunctions in overcoming current performance bottlenecks, paving the way for scalable, ultrafast photonic devices with superior performance and reliability.