Microstructure modulation of the CH₃NH₃PbI₃ layer in perovskite solar cells by 2-propanol pre-wetting and annealing in a spray-assisted solution process

Abstract

As the light absorption layer, a CH 3 NH 3 PbI 3 perovskite film with fully and homogenously covered flat surface is crucially important for perovskite photovoltaic device. Herein, the sequential method is improved by introducing spray-assisted solution process (SSP) instead of commonly used dipping process in CH 3 NH 3 PbI 3 perovskite film deposition. The morphology analysis for PbI 2 films found that the airflow of spray pre-wetting process provides a driving force for accelerating the dissolution and deep infiltration, which is helpful to form mesoporous PbI 2 scaffold. So the 2-propanol (IPA) prewetting has advantage to complete the reaction of PbI 2 and CH 3 NH 3 I through the diffusion channel in the grain boundary and on the surface of the PbI 2 film. Furthermore, the grain size and surface coverage of the film can be controlled effectively by a facile IPA prewetting in the SSP. Meanwhile, The influences of annealing process on crystallization, chemical composition, microstructures and carrier transport property of perovskite films were investigated. Our results showed that proper annealing temperature and time can reduce crystal defect in the film and weaken the hysteresis phenomenon of the perovskite solar cell. Efficient mesoporous structured perovskite solar cells were fabricated with optimal PCE of 14.2%, because of the improved perovskite film preparation method.

Controlled Deposition and Performance Optimization of Perovskite Solar Cells Using Ultrasonic Spray‐Coating of Photoactive Layers

“…[33] After that, several recent reports furthero utlined new opportunities for spray technology in the field of perovskite solar cells. [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] The goal to achieveprintable perovskite solar cells by using spray-coating can be justifiedb y the processability of depositing solutions and post-processing treatment in as imple and low-cost way.G iven that spray-deposition has great potential for continuous processes, af undamental investigation on how the aforementionedk ey factors affect the quality and the performance of solution-processed perovskite thin-films used in solar cells is necessary.…”

Reduced Defects of MAPbI3 Thin Films Treated by FAI for High‐Performance Planar Perovskite Solar Cells

“…Zhao and co‐workers showed that the MAPbI 3 perovskite treated by a dilute methylammonium bromide solution would effectually increase crystallinity of the MAPbI 3 layer . The crystal structure of perovskite layer can also be improvement by post‐growth treating with the vapor of organic halides, polar solvents, or pyridine vapor …”

Progress in Scalable Coating and Roll‐to‐Roll Compatible Printing Processes of Perovskite Solar Cells toward Realization of Commercialization

“…(a)–(c) Reproduced with permission . Copyright 2015, American Chemical Society; (d),(e) Reproduced with permission . Copyright 2016, Royal Society of Chemistry; (f)–(i) Reproduced with permission .…”

“…To solve this problem, some research groups created porous PbI 2 film prior to reacting with MAI for complete conversion while preventing perovskite crystal from being partially converted. Yu and co‐workers suggested an IPA prewetting process, as shown in Figure d . Compared to the conventional dipping process, the airflow of the spray prewetting process facilitated the formation of a porous PbI 2 scaffold and accelerated the dissolution and deep infiltration of the MAI solution.…”