A Versatile Molten‐Salt Induction Strategy to Achieve Efficient CsPbI3 Perovskite Solar Cells with a High Open‐Circuit Voltage >1.2 V

• Published in: Advanced materials (Weinheim) Vol. 34; no. 45; pp. e2205028 - n/a
• Main Authors: Cui, Yuqi, Shi, Jiangjian, Meng, Fanqi, Yu, Bingcheng, Tan, Shan, He, Shan, Tan, Chengyu, Li, Yiming, Wu, Huijue, Luo, Yanhong, Li, Dongmei, Meng, Qingbo
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.11.2022
• Subjects: Circuits; CsPbI 3; Electric potential; Energy conversion efficiency; intermediate phase; Molten salts; perovskite solar cells; Perovskites; Photovoltaic cells; room‐temperature molten salts; Solar cells; Thermal stability; V OC deficit; Voltage
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202205028

All‐inorganic CsPbI3 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 CsPbI3 solar cells is mainly subject to a large open‐circuit voltage (VOC) 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 CsPbI3 film for high‐efficiency photovoltaics. DMAAc can stabilize the DMAPbI3 structure and eliminate the Cs4PbI6 intermediate phase, which is easily spatially segregated. Meanwhile, a new homogeneous intermediate phase DMAPb(I,Ac)3 is formed, which finally affords high‐quality CsPbI3 films. With this approach, the charge capture activity of defects in the CsPbI3 film is significantly suppressed. Consequently, a VOC 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. A room‐temperature molten salt dimethylamine acetate is developed as the solvent for precursor solutions, which also regulates the phase conversion process of the CsPbI3 film. Consequently, 1.25 V of the open‐circuit voltage and >21% power conversion efficiency are achieved, which is the record highest for CsPbI3 perovskite solar cells reported so far.