CsAc-Mediated Dynamic Reconstruction of Chloride Perovskite Films for High-Performance Self-Powered Near-UV Photodetectors

Methylammonium lead chloride perovskite (MAPbCl3), with its wide bandgap of ∼3 eV, exhibits unique advantages for near-UV to UV optoelectronic devices. However, the fast crystallization kinetics and significant solubility differences of MAPbCl3 precursors in solvents cause discontinuous films with high surface defect densities, severely limiting device performance. This study introduces a solution mediated dissolution recrystallization strategy to address the aforementioned issues, namely, employing a CsAc/methanol solution to dynamically reconstruct preformed MAPbCl3 films. During this process, Cs+ doping regulates the crystallization kinetics and suppresses the formation of pinholes caused by nonequilibrium crystallization, and Ac– anions passivate grain boundaries and surface defects through coordination. This synergistic approach yields dense, high-quality Cs0.35MA0.65PbCl3 polycrystalline films. The resulting self-powered photodetector demonstrates exceptional performance under 405 nm laser excitation: an on/off ratio of 1.38 × 106, responsivity of 0.278 A/W, detectivity of 3.49 × 1012 Jones, and a response time of 16 μs. These metrics significantly surpass those of previously reported solution-processed counterparts. This work offers a new pathway for fabricating high-quality chloride-based perovskite films and facilitates their application in optoelectronic devices such as transparent solar cells and radiation detectors.