Multiple Synergistic Mechanisms of Urea in Vacuum‐Assisted Prepared Triple‐Cation Perovskite Solar Cells

Triple‐cation perovskites have attracted significant attention as promising photovoltaic materials due to their excellent optoelectronic properties. However, the resulting solar cells remain limited by issues such as crystal defects and poor film uniformity. In this study, we introduce urea as a multifunctional additive to fabricate triple‐cation perovskite solar cells with a bandgap of 1.61 eV. Incorporating urea into the precursor solution enhances coordination between its amino and carbonyl groups and the perovskite components, effectively slowing the crystallization kinetics during vacuum‐assisted deposition. Consequently, the films exhibit significantly improved crystal orientation and enlarged grain size. Urea also serves as an effective passivator, mitigating various defects within the perovskite lattice due to its small molecular structure and active functional groups. This dual function yields an optimized perovskite solar cell with a champion PCE of 19.61%, demonstrating the strategy's efficacy in enhancing both film quality and device performance.