Fluorocarbon‐based Solvent‐Bath Annealing for High‐Performance Perovskite Photovoltaics

Abstract Thermal annealing is a critical process in producing high‐quality perovskite films for high‐performance perovskite solar cells. Conventional TA presents challenges such as delayed heat transfer, leading to unwanted crystal growth and hindering processing scalability. Solvent‐bath annealing is an attractive approach that can improve heat transfer and promote perovskite crystallization by immersing the as‐deposited precursor film in a liquid medium. In this study, fluorocarbon‐based solvents are developed as novel solvent baths for uniform heat flow through omnidirectional annealing. In addition, the previously neglected solvent‐to‐solvent interaction between fluorocarbon and solvents for perovskite precursor is investigated by comparing two fluorocarbon solvents. By increasing the solvent‐solvent interaction, higher quality perovskite films with increased crystallinity, improved perovskite transition, and reduced film defects are achieved. As a result, the perovskite solar cells exhibited an increased power conversion efficiency with excellent reproducibility. These findings suggest that the selection of suitable solvent bath is promising for further improving perovskite quality and device performance.