Electrode annealing of methylammonium lead halide organic perovskite film

Organic perovskites have shown significant potential in optoelectronic device applications. However, these materials are susceptible to degradation by water and oxygen. A critical factor for practical applications is the preparation of highly crystalline films to enhance stability. In this study, we introduce a novel annealing method, termed electrode annealing, to produce high-quality methylammonium lead halide (CH₃NH₃PbI₃, MAPbI₃) organic perovskite films by applying a bias to the sample. Using a solution process with optimized parameters, we prepared MAPbI₃ films with a transparent intermediate phase structure on Glass/Indium Tin Oxide (ITO) substrates. Subsequently, the phase transformation from the intermediate phase to the perovskite crystal was achieved through a low thermal budget annealing process, utilizing electric current-induced Joule heating of the ITO electrode under bias. This electrode annealing method established a temperature gradient along the film thickness and induced an electric current effect on the ITO surface, promoting preferential nucleation of the perovskite phase at the ITO/MAPbI₃ interface. As a result, the MAPbI₃ films developed a columnar grain structure with large grain sizes, fewer defects, and lower contamination levels. This high-quality MAPbI₃ film demonstrated improved resistance to atmospheric degradation.