Additive Engineering in Crystallization Regulation of Highly Efficient Perovskite Solar Cell

Metal halide perovskites are promising solar cell materials due to excellent photoelectric performance. High-quality films are crucial for stable perovskite solar cells (PSCs). However, defects, pinholes, and small grains hinder fabrication, causing nonradiative recombination. Among crystallization regulation strategies, additive engineering is versatile and effective for optimizing film quality via crystal growth control. This review summarizes the role of additive engineering in modulating crystallization across different perovskite types. For formamidinium (FA)-based perovskites, additives address problems like rapid crystallization, unstable secondary phases, residual stress, and random orientation, thereby stabilizing the phase and reducing grain boundaries. For methylammonium (MA)-based perovskites, additives (e.g., Lewis base-containing compounds and biomass-derived cellulose derivatives) adjust the lattice structure, slow down crystallization through intermediate adducts, and enhance grain alignment and defect healing. For all-inorganic CsPbX3, additives (e.g., alkylamines and liquid monomers) decelerate crystallization to enlarge grains, decrease roughness through ion coordination, and form hydrophobic grain boundaries. Mechanistically, additives adjust crystallization kinetics, passivate defects via ion coordination, relieve residual stress, and direct preferential growth. This review offers insights for scalable high-quality film fabrication—essential for PSC commercialization—with future exploration of additives is set to further unlock PSC performance.