Film Deposition Techniques Impact the Defect Density and Photostability of MAPbI3 Perovskite Films

Over the last decade, perovskite solar cells (PSCs) have demonstrated tremendous growth in power conversion efficiencies. Different strategies toward developing new perovskite film deposition techniques were of particular help in such progress. Considering generally the poor operational stability of PSCs, understanding the influence of deposition methods on the stability of lead halide perovskite films is vital to facilitate further practical application of this technology. Herein, we studied the impact of CH3NH3PbI3 deposition methods on the photostability of perovskite films. In particular, one-step deposition in a nitrogen and an ambient air atmosphere, two-step and chemical vapor deposition, as well as close-space sublimation methods were explored. We revealed that the lifetime of absorber films under light exposure can be spectacularly extended by a factor of 2-3 when using an appropriate deposition technique. In particular, the films grown by chemical vapor deposition showed superior photostability compared to the samples obtained by other methods. A clear correlation between the concentration of defects in perovskite films and their photostability was revealed, while the grain size was shown to have a minor effect under anoxic conditions. We believe that these findings are essentially important for improving the operational lifetime of perovskite solar cells and facilitating their commercialization.