Slot‐Die Coating of Ammonium Salt Passivation Layer for High‐Performance Perovskite Solar Cells and Modules

Scaling up high‐performance perovskite solar cells (PSCs) while avoiding losses in the power conversion efficiency (PCE) is a challenging task. Surface passivation of the perovskite film has been demonstrated as an effective strategy to mitigate PCE losses. However, there is limited research on scalable surface passivation techniques. Herein, we studied how to develop a slot‐die coating technique applying for passivation layers to PSCs, which can be adapted for industrial‐scale production. Molecular structure of passivators and coating parameters have been systematically optimized to achieve high‐quality film morphology, which enable effectively inhibition of interface recombination. As a result, champion efficiencies of 22.4% for small‐size solar cells (0.16 cm 2 ) and 18.3% for solar modules (10.0 cm 2 ) have been achieved with 4‐bromophenethylammonium chloride. Moreover, the encapsulated solar cells retained 89% of their initial performance after continuous operation under 100 mW·cm 2 illumination for 400 h.