The Role of EA:EtOH Mixed Antisolvents in Optimizing Crystallization of CsPbBr₃ Films

CsPbBr₃ perovskite solar cells have attracted significant attention due to their outstanding stability and ease of fabrication. However, challenges remain regarding the uniformity of film crystallization and efficiency of the devices, which necessitate further improvements. Antisolvent washing is an effective approach to enhance the crystallization quality of perovskite films. In this study, we present an optimized antisolvent rinsing strategy utilizing a multi-step spin-coating method for the fabrication of CsPbBr₃ films. In the mixed antisolvent of ethyl acetate (EA) and ethanol (EtOH), increasing the volume ratio of EtOH results in a decrease in the number of pinhole defects in CsPbBr₃ films, as well as an increase in the average grain size. When the volume ratio of EA to EtOH is set at 8:2, the average grain size attains an optimal value of 648   nm. Devices based on the FTO/c-TiO₂/m-TiO₂/CsPbBr₃/carbon structure treated with the EA:EtOH (8:2) mixed antisolvent achieved a maximum power conversion efficiency (PCE) of 7.22%. The improvement in device efficiency is primarily attributed to enhanced charge transport and reduced defect density, which collectively suppress non-radiative recombination. Additionally, after 720   hours of storage in ambient air with 40-50% relative humidity, the devices retained 93% of their initial efficiency. This work provides valuable insights into the development of highly efficient and stable CsPbBr₃ perovskite solar cells.