A Versatile Molten‐Salt Induction Strategy to Achieve Efficient CsPbI<sub>3</sub> Perovskite Solar Cells with a High Open‐Circuit Voltage >1.2 V
Yuqi Cui, Jiangjian Shi, Fanqi Meng, Bingcheng Yu, Shan Tan, Shan He, Chengyu Tan, Yiming Li, Huijue Wu, Yanhong Luo, Dongmei Li, Qingbo Meng
Abstract
Abstract All‐inorganic CsPbI 3 perovskite has emerged as an important photovoltaic material due to its high thermal stability and suitable bandgap for tandem devices. Currently, the cell performance of CsPbI 3 solar cells is mainly subject to a large open‐circuit voltage ( V OC ) deficit. Herein, a multifunctional room‐temperature molten salt, dimethylamine acetate (DMAAc) is demonstrated, which not only directly acts as a solvent for precursor solutions, but also regulates the phase conversion process of the CsPbI 3 film for high‐efficiency photovoltaics. DMAAc can stabilize the DMAPbI 3 structure and eliminate the Cs 4 PbI 6 intermediate phase, which is easily spatially segregated. Meanwhile, a new homogeneous intermediate phase DMAPb(I,Ac) 3 is formed, which finally affords high‐quality CsPbI 3 films. With this approach, the charge capture activity of defects in the CsPbI 3 film is significantly suppressed. Consequently, a V OC of 1.25 V and >21% power conversion efficiency are achieved, which is the record highest reported thus far. This intermediate phase‐regulation strategy is believed to be applicable to other perovskite material systems.