Investigation of Cation Exchange Behaviors of FA(x)MA(1-x)PbI(3) Films Using Dynamic Spin-Coating

Abstract

In this study, we fabricated and characterized uniform multi-cation perovskite FA(x)MA(1-x)PbI(3) films. We used the dynamic spin-coating method to control the cation ratio of the film by gradually increasing the FA+, which replaced the MA+ in the films. When the FA+ concentration was lower than xFA ~0.415 in the films, the stability of the multi-cation perovskite improved. Above this concentration, the film exhibited delta-phase FAPbI(3) in the FA(x)MA(1-x)PbI(3) films. The formation of delta-phase FAPbI(3) disturbed the homogeneity of the photoluminescence spatial distribution and suppressed the absorption spectral bandwidth with the increasing bandgap. The precise control of the cation ratio of multi-cation perovskite films is necessary to optimize the energy-harvesting performance.