Enhancing Organic-Inorganic Perovskite Thin Film Crystallization via Vapor-Solid Reaction by Modifying PbI2 Precursors Films with Pyridinium Trifluoromethanesulfonate

The vapor-solid reaction technique holds potential for producing large-scale organic-inorganic perovskite films, using a two-step deposition process. The sucess of perovskite formation heavily relies on the crystallization of lead iodide (PbI2) precursor films. However, the high crystallinity of PbI2 can hinder organic vapors' diffusion and negatively affecting the solar cells by increasing charge recombination and accelerating degradation. To address this, pyridinium trifluoromethanesulfonate (PTFS) is introduced into the PbI(2 )precursor solution to control the nucleation and growth of PbI2 films. PTFS has been found to effectively suppresses PbI2 crystallization and enhance the integration of formamidinium ion (FA(+)) through hydrogen bonding, facilitating the full transformation of PbI2 into perovskite. It also minimizes defect formation by interacting with uncoordinated Pb2+ and FA+ ions. These modifications have significantly enhanced power conversion efficiency (PCE), reaching up to 21.19%, and the devices have maintained 93% of their initial performance after 1580 h of exposure to air.