Aluminum‐Doped Indium Oxide Electron Transport Layer Grown by Atomic Layer Deposition: Highly Efficient and Damage‐Resistant Interconnection Solution for All‐Perovskite Tandem Solar Cells with 25.46% Efficiency

Abstract In fabricating high‐efficiency all‐perovskite tandem solar cells (APTSCs) with a p‐i‐n configuration, the electron transport layer (ETL) plays a critical role in facilitating the transport of photogenerated electrons from the front cell to the recombination layer and protecting the front cell from damage during rear cell fabrication. This study introduces aluminum‐doped In₂O₃ (AIO) films grown by atomic layer deposition (ALD) as a promising ETL for high‐efficiency APTSCs. ALD‐grown AIO films with an optimized Al concentration exhibit superior charge transport characteristics, excellent transparency, and damage‐resistant barrier properties against solution infiltration compared with conventional SnO₂ ETLs and undoped ALD In₂O₃. Using an ALD SnO₂/3 at.% AIO bilayer as the electron transport layer, an efficiency of 18.33% is achieved from single‐junction wide bandgap perovskite solar cells. Furthermore, the use of ALD SnO₂/3 at.% AIO ETL enables the reliable fabrication of APTSCs with negligible solution damage to the front cell and minimized power loss. Consequently, APTSC employing the ALD AIO‐based ETL exhibit an excellent photoconversion efficiency of 25.46%, outperforming APTSCs with the ALD SnO₂ ETL.