Modified Chemical Bath Deposition of Tin Oxide for All‐Scalable Perovskite Solar Modules

Chemical bath deposition (CBD) of tin oxide is a commercially viable method for manufacturing the electron transport layer in perovskite solar cells, yet it remains highly sensitive to reaction conditions, particularly pH . This study introduces tin‐like cation, namely Pb 2+ , as a chemical modulator to stabilize the CBD process. Due to nearly two orders of magnitude higher solubility of lead hydroxide (Pb(OH) 2 ) as compared to tin hydroxides (Sn(OH) 2 and Sn(OH) 4 ), Pb(OH) 2 acts as an OH − scavenger, reducing free excess OH − concentration and suppressing premature tin oxide (SnO x ) precipitation. This enables the formation of smooth, uniform SnO x films. Perovskite photovoltaics fabricated on these SnO x films via ambient and scalable processes achieve a power conversion efficiency of 24.5% for cells (and 17.8% for solar modules), retaining >84% of initial performance after 1000 h of operation under maximum power point tracking (MPPT) at 65 ± 5 °C.