Solution slot-die coating perovskite film crystalline growth observed by <i>in situ</i> GIWAXS/GISAXS

Abstract

Solution method is an important fabrication means of optoelectronic devices. During the thin film sample preparation, organic or inorganic perovskite semiconductor materials usually needs to be finished in the glove box. However, most of the traditional experimental characterization under the environment of air, it is hard to reflect the reality of the structure and performance between films and devices, therefore urgently need to solve the microstructure evolution of these semiconductor films based on in situ real-time representation techniques. It is encouraging that we reported a synchrotron-based grazing incidence wide and small-angle scattering (GIWAXS and GISAXS) in situ real-time observation technique in combining with a mini glove box, which can realize the standard glove box environment (H₂O, O₂ content all reached below 1 ppm) under remote control film spin coating or slot-die preparation and a variety of sample post-processing. Meanwhile, this technique can real-time monitor the microstructure and morphology evolution of semiconductor films during fabrication. Based on the in situ device and GIWAXS, SnO₂ ETL interface induced perovskite growth crystallization process found that CQDs additive can result two dimensional perovskite with the random orientation growth changing into highly ordered vertical orientation, meanwhile can effectively restrain the low-level two-dimensional perovskite domains formation, helping to reveal the film microstructure transformation of inner driving force and providing the perovskite device preparation process optimized with experimental and theoretical basis. The conversion efficiency of large-area fully flexible 3D perovskite thin film solar cells prepared by the roll-to-roll total solution slit coating method was increased to 5.23% (the area of a single device was ~15cm²). Therefore, based on the in situ synchrotron-based glove box device can investigate microstructure evolution and the associated device preparation conditions of perovskite and organic semiconductor thin films, further control of thin film growth interface characteristics and film quality, which is the key technology to guide the optimization process conditions of semiconductor thin films and devices.