KCl-Mediated Defect Passivation in Vapor-Deposited Perovskites

Perovskite-based solar cells (PSCs) have reached efficiencies comparable to those of commonly used silicon solar panels. Despite the promise of PSCs, their efficiency and commercial viability are currently restricted by three main factors: nonradiative charge recombinations on defects occurring within the light-absorbing layer and at its boundaries, limited reproducibility, and upscaling due to widely employed wet deposition methods. To address these issues, we investigated the defect passivation strategy by introducing potassium salt (KCl) during perovskite vapor deposition. We observed effective passivation of the defects upon KCl addition, manifested as an immediate and significant enhancement of the real-time photoluminescence (PL) intensity. The efficiency of passivation is related to the ionic nature of the potassium salt and its flux density. On the other hand, the perovskite's crystallographic structure and texture, as observed from the grazing-incidence wide/small-angle X-ray scattering measurements, showed no significant changes due to KCl doping. Our work provides valuable insight into the possible passivation routes for the vapor-deposited perovskite layers, with implications for various chemical compositions or architectures.