Coordination‐Induced Defects Elimination of SnO<sub>2</sub> Nanoparticles via a Small Electrolyte Molecule for High‐Performance Inverted Organic Solar Cells
Huaizhi Gao, Xueqi Wei, Runnan Yu, Fong‐Yi Cao, Yongshuai Gong, Zongwen Ma, Yen‐Ju Cheng, Chain‐Shu Hsu, Zhan’ao Tan
Abstract
Abstract Tin oxide (SnO 2 ) is broadly used as an electron transport layer (ETL) in organic solar cells (OSCs). However, there are many hydroxyl groups and the defects of oxygen vacancy on the surface of SnO 2 , resulting in charge recombination. Herein, an electrolyte 4‐(dimethyl(pyridin‐2‐yl) ammonio)butane‐1‐sulfonate (PAS) is doped into SnO 2 films with an appropriate proportion to improve the performance of the inverted OSCs. The PAS can coordinate with the Sn atoms in SnO 2 films to reduce the surface defects, resulting adjustable work function and increased electron conductivity. Meanwhile, the PAS doping can decrease the surface energy of SnO 2 layer, forming vertical phase distribution of the active layer for better exciton dissociation and charge transport. The PM6:Y6 based inverted OSC with SnO 2 ETL shows a power conversion efficiency (PCE) of 14.72%, while the device with PAS‐doped SnO 2 ETL demonstrates greatly enhanced PCE of 16.37%. The device performance can be further improved by using PM6:BTP‐eC9 as active layer and a PCE of 17.12% can be achieved with PAS‐doped SnO 2 ETL. Furthermore, PAS‐doped SnO 2 can effectively enhance the device stability under continuous illumination. These findings demonstrate that exquisite regulation of SnO 2 layer via a small electrolyte molecule coordination is a promising approach to achieve efficient and stable inverted OSCs.