Polysaccharide Modified SnO2 for Highly Efficient Perovskite Solar Cells

Tin oxide (SnO 2 ) has been demonstrated as a promising electron transport material for perovskite solar cells (PSCs) due to its low‐temperature process and high charge extraction ability. However, the key to improving the internal performance of PSCs toward unity lies in the ability of enhancing bulk SnO 2 quality and reducing the energy level mismatch between SnO 2 and perovskite layer. Herein, a facile and effective strategy to simultaneously functionalize SnO 2 structure by sodium alginate (SA) polysaccharide compound is reported. The investigations reveal that SA leads to the formation of nanosynapse structure of SnO 2 films, which allows the aligned energy levels and suppressed charge recombination, significantly enhancing carrier extraction and transport. Consequently, CsMAFAPb(I x Br 1− x ) 3 and CsPbI 2 Br solar cells achieve a remarkable power conversion efficiency of 24.11% and 16.90%, respectively, based on SnO 2 ‐SA electron transport layers (ETLs). This work offers a facile and effective way to fabricate high‐performance SnO 2 ETL in PSCs.