Control of Methylamine Gas Treatment for Upscaling Perovskite Solar Module

Abstract

Methylamine (MA⁰) gas treatment (MATM) is a process that involves the adsorption of MA⁰ on methylammonium (MA)-based lead perovskite thin films, forming an adsorption intermediate, which appears as a visually transparent liquid. When MA⁰ is desorbed from this intermediate, recrystallization of the MA-based perovskite occurs. Due to the highly reversible nature of MATM and its ability to inherently levelize the film surface through liquefaction, MATM is a promising method for fabricating uniform and intact perovskite thin films over large areas, which is crucial for the commercialization of perovskite solar cells. Herein, efforts to control the MATM process are presented, including slowing down the kinetics of MA adsorption by introducing a diluent into the MA stock solution, establishing a monitoring system to investigate the desorption process in detail, and demonstrating the success of MATM in fabricating perovskite solar modules. It is found that MATM not only heals morphological flaws but also promotes (110) orientation crystallinity and reduces trap density in recrystallized MAPbI₃ films. Finally, MATM is applied to prepare perovskite minimodules using an in-house designed MA-induced liquefaction and recrystallization reactor. The minimodule (5 × 5 cm) fabricated using MATM achieves 18.32% efficiency, significantly surpassing the performance of those fabricated using antisolvent-treating (7.50%) and vacuum drying (16.09%) methods.