SnO<sub>2</sub> Interacted with Sodium Thiosulfate for Perovskite Solar Cells over 25% Efficiency
Tianyu Xia, Yunfei Ouyang, Can Wang, Yi Pan, Qin Gao, Xiao Chen, Bo Zhang, Kun Chen, Zijuan He, Xiangbao Yuan, C.F. Shen, Bing Guo, Yehao Deng, Shijian Chen, Tingming Jiang, Kuan Sun
Abstract
Tin oxide (SnO 2 ) as electron transportation layer (ETL) has demonstrated remarkable performance applied in perovskite solar cells but still accommodated a host of defects such as oxygen vacancies, uncoordinated Sn 4+, and absorbed hydroxyl groups. Here, we use inorganic sodium thiosulfate Na 2 S 2 O 3 to modify SnO 2 nanoparticles in a bulk blending manner. Strong interaction between Na 2 S 2 O 3 and SnO 2 occurs, as reflected from the elemental chemical state change. The interaction has endowed the SnO 2 film with better uniformity, increased conductivity, and more matched energy level with perovskite. Moreover, the modified SnO 2 film as a substrate could promote the crystallization of perovskite by suppressing unreacted residual PbI 2 . The trap density from perovskite bulk to the SnO 2 film across their interface has been effectively reduced, thus inhibiting the nonradiative recombination and promoting the transportation and extraction of charge carriers. Finally, the solar cell based on modified SnO 2 has achieved a champion efficiency of 25.2%, demonstrating the effectiveness and potential of sulfur-containing molecules on optimizing the SnO 2 property.