Dual-Channel Poly(vinyl alcohol) Engineering Enhanced Synergistic Bulk-Surface Passivation for High-Performance and Stable Perovskite Photodetectors

This study presents a synergistic passivation strategy employing poly(vinyl alcohol) (PVA) to concurrently mitigate surface and bulk iodine vacancy defects in perovskite photodetectors (PPDs). Through the dual incorporation of PVA in precursor solutions and post-treatment solutions, we establish a hierarchical protection mechanism: Oxygen-functional groups in PVA form stable coordination complexes with undercoordinated Pb2+ species, achieving a 32.3% reduction in defect density, while simultaneously creating moisture/oxygen-resistant barriers through grain boundary encapsulation. This dual-function approach effectively suppresses nonradiative recombination pathways, resulting in a 2-fold enhancement of carrier lifetimes. The optimized PPDs achieve a responsivity of 0.184 A/W and a detectivity of 2.55 × 1011 Jones. Remarkably, unencapsulated devices maintain 90% of initial performance following 360 h ambient exposure (T90 > 360 h). The universality of this strategy is validated across I/Br/Cl-based perovskite systems. Combined with solution-processability and room-temperature fabrication compatibility, this approach provides a scalable platform for industrial production of stable perovskite optoelectronics.