In Situ Probing the Crystallization Kinetics in Gas‐Quenching‐Assisted Coating of Perovskite Films

Abstract

The pursuit of commercializing perovskite photovoltaics is driving the development of various scalable perovskite crystallization techniques. Among them, gas quenching is a promising crystallization approach for high‐throughput deposition of perovskite films. However, the perovskite films prepared by gas‐quenching assisted blade coating are susceptible to the formation of pinholes and frequently show inferior crystallinity if the interplay between film coating, film drying, and crystallization kinetics is not fully optimized. That arguably requires a thorough understanding of how single processing steps influence the crystallization kinetics of printed perovskite films. Here, in situ optical spectroscopies are integrated into a doctor‐blading setup that allows to real‐time monitor film formation during the gas‐quenching process. It is found that the essential role of gas quenching treatment is in achieving a smooth and compact perovskite film by controlling the nucleation rate. Moreover, with the assistance of phase‐field simulations, the role of excessive methylammonium iodide is revealed to increase grain size by accelerating the crystal growth rate. These results show a tailored control of crystal growth rate is critical to achieving optimal film quality, leading to fully printed solar cells with a champion power conversion efficiency of 19.50% and mini solar modules with 15.28% efficiency are achieved.

Blade-Coating of High Crystallinity Cesium-Formamidinium Perovskite Formulations

“…This conversion process could be then further visualized by in situ optical microscopy observations on top of coated inks 54 and SEM observations of perovskite films at different annealing times/temperatures. 55 It might also be interesting to complement this study with phase field simulations to link nucleation rate, growth rate, and final film morphology and properties (e.g., with various amounts of TU) as studied in previous studies 56 , 57 to obtain a composition optimized both for the deposition process (faster kinetics in the case of blade-coating) and for the final film quality (high crystallinity and defect-free perovskite).…”