Analysis of macroscopic cracks in triple cation perovskite films fabricated by the anisole antisolvent method

Abstract

The most efficient perovskite solar cells (PSCs) are currently developed using antisolvent-based fabrication technology. Despite extensive analysis of various aspects of the antisolvent method—such as the type of antisolvent, dropping time, and precursor compatibility—some antisolvents still produce uneven film surface morphology on centimeter-scale substrates. The decoupling of the relationship between local structural characteristics, such as grain boundaries and defects, and the optoelectronic performance of PSCs is currently one of the most highly regarded research issues in the field. In this study, we utilized high-resolution white light interferometry to characterize the morphological distributions of perovskite films from the center to edge, using anisole as an example of the antisolvent. We observed that macro cracks at the center of the film typically exhibit dense ridge morphology, while cracks toward the edges display a concave morphology. We analyze the stress mechanism by using EDS mapping and AFM in detail, attributing this phenomenon to the competitive attachment of 2D islands and boundaries for adatoms, which are influenced by changes in grain size. The devices at different locations were fabricated and their performance analyzed. Our findings indicate that these protruding cracks do not significantly affect the current and voltage of the photovoltaic device; however, concave cracks lead to a decrease in the device fill factor. We attribute this decrease to enhanced carrier recombination at the interface due to this morphology. This study provides valuable insights into the formation of perovskite film morphology under antisolvent treatment and the relationship between film local morphology and PSCs performance.