Reactive Plasma Deposition of ITO as an Efficient Buffer Layer for Inverted Perovskite Solar Cells

Abstract In this study, the potential of reactive plasma deposition (RPD) is demonstrated for fabricating indium tin oxide (ITO) as an efficient buffer layer in inverted wide‐bandgap perovskite solar cells (PSCs). This method results in a certified efficiency of 21.33% for wide‐bandgap PSCs, demonstrating superior thermal stability and operational stability. The optimized devices achieve an impressive open‐circuit voltage ( V OC ) of 1.252 V with a bandgap of 1.67 eV, resulting in a remarkably low voltage deficit of 0.418 V, attributed to improved electron extraction, reduced interface defects, and suppressed surface recombination. The cells maintain over 90% of their initial efficiency after 1023 h of thermal aging at 88 °C. Furthermore, by integrating a highly efficient semi‐transparent PSC with a CIGS bottom cell, a four‐terminal tandem configuration is achieved with a total efficiency of 29.03%, representing one of the most efficient perovskite/CIGS tandem solar cells reported to date. This study provides valuable insights into the potential of RPD for improving the performance and scalability of inverted wide‐bandgap PSCs.