All-Inorganic Perovskite Solar Cells with Tetrabutylammonium Acetate as the Buffer Layer between the SnO<sub>2</sub> Electron Transport Film and CsPbI<sub>3</sub>
Hang Zhong, Wenbo Li, Yin Huang, Duoling Cao, Congqiang Zhang, Huaxi Bao, Zhiguang Guo, Li Wan, Xu Zhang, Xu Zhang, Xun Zhang, Xun Zhang, Yuebin Li, Xiao‐Ming Ren, Xianbao Wang, Dominik Eder, Kai Wang, Shengzhong Liu, Shimin Wang
Abstract
All-inorganic CsPbI3 perovskites have great potential in tandem cells in combination with other photovoltaic devices. However, CsPbI3 perovskite solar cells (PSCs) still face a huge challenge, resulting in a low power conversion efficiency (PCE) relative to organic–inorganic PSCs. In this work, we introduced tetrabutylammonium acetate (TBAAc) as a buffer layer between the SnO2 electron-transport layer (ETL) and CsPbI3 all-inorganic perovskite film interface for the first time. TBAAc not only improved the conductivity of SnO2 ETL but also formed a 1D TBAPbI3 layer between the SnO2 ETL and the 3D CsPbI3 all-inorganic perovskite film, thereby enhancing the stability and passivating the surface defects of the CsPbI3 perovskite to fabricate high-efficiency carbon-counter electrode (CE)-based CsPbI3 solar cells. We fabricated carbon-CE-based hole-transporting layer ( HTL)-free PSCs with an FTO/SnO2/TBAAc/CsPbI3/C structure. The open-circuit voltage (Voc), short circuit current density (Jsc), PCE, and fill factor of the champion CsPbI3 PSCs simultaneously enhanced to 1.08 V, 17.48 mA/cm2, 12.79, and 67.8%, respectively. This PCE is currently one of the high efficiencies reported for the above planar-structured carbon-CE-based CsPbI3 PSCs to date. Moreover, the optimized device exhibits excellent stability, which retained over 83% of its initial PCE after 350 h. This work provides a facile way of simultaneous optimization of the SnO2 ETL and the CsPbI3 perovskite layer to fabricate stable and high-efficiency carbon-CE-based CsPbI3 PSCs.