Impact of Electrode Materials on Process Environmental Stability of Efficient Perovskite Solar Cells

For commercializing perovskite solar cells (PSCs), moisture-tolerant materials are required because a moisture-free environment cannot be maintained on an actual production line (large scale). Recently, PSCs with efficiency exceeding 22% have been fabricated using Li-doped mesoporous TiO₂ as an electron transport layer (ETL). However, the use of Li can negatively influence device stability during the fabrication process under humid air because of its hydroscopic property. Here, we report a strategy for improving processing stability without sacrificing the power conversion efficiency (PCE) under a humid atmospheric environment by employing a mesoporous BaSnO₃ as an ETL. Using the mesoporous BSO ETL, we achieved a certified efficiency of 21.3% and stabilized efficiency of 21.7%. Furthermore, the BSO-based PSCs also exhibited better processing stability than Li-doped TiO₂-based PSCs under humid air. We believe that this strategy of introducing BSO into PSCs will accelerate the commercialization of PSCs.