Regulating Solution Spreading and Intermediate Phase Evolution for Large-Area Perovskite Films and Solar Modules

Abstract

Halide perovskite films are commonly fabricated using a variety of deposition equipment. The self-spreading method, in contrast, offers a simple and equipment-free alternative for film preparation. However, previous implementations of this method have been limited to small-area, circular films. In this work, we present strategies to control the spreading and crystallization behavior of perovskite solutions through the use of solvent and solid additives, enabling the fabrication of large-area (up to 100 cm²) perovskite films via selfspreading under ambient conditions. The effects of these additives on the crystallization process are elucidated using in-situ light absorption spectroscopy, which reveals distinct reaction pathways depending on the additive composition. High-quality perovskite films are prepared in air without using antisolvent or vacuum-assisted processing, leading to solar cells with a power conversion efficiency (PCE) of 23.61%. Furthermore, we demonstrate a laser-free module fabrication process, achieving a high geometric fill factor of 97.3% and a PCE of 19.88% (aperture area: 14.1 cm²)-the highest PCE (aperture area) for perovskite solar modules fabricated using non-laser processing. This study highlights a scalable and cost-effective route toward high-performance perovskite solar cells and modules.