Cesium Lead Inorganic Solar Cell with Efficiency beyond 18% via Reduced Charge Recombination

• Published in: Advanced materials (Weinheim) Vol. 31; no. 49; pp. e1905143 - n/a
• Main Authors: Ye, Qiufeng, Zhao, Yang, Mu, Shaiqiang, Ma, Fei, Gao, Feng, Chu, Zema, Yin, Zhigang, Gao, Pingqi, Zhang, Xingwang, You, Jingbi
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.12.2019
• Subjects: Cesium; Circuits; Conduction bands; Efficiency; Electron transport; Energy conversion efficiency; Energy levels; inorganic perovskite solar cells; Lead chlorides; Lithium; Lithium fluoride; Perovskites; Photovoltaic cells; recombination defects; Solar cells; Tin dioxide; VOC loss; VOC loss; inorganic perovskite solar cells; recombination defects
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.201905143

Cesium‐based inorganic perovskite solar cells (PSCs) are promising due to their potential for improving device stability. However, the power conversion efficiency of the inorganic PSCs is still low compared with the hybrid PSCs due to the large open‐circuit voltage (VOC) loss possibly caused by charge recombination. The use of an insulated shunt‐blocking layer lithium fluoride on electron transport layer SnO2 for better energy level alignment with the conduction band minimum of the CsPbI3‐xBrx and also for interface defect passivation is reported. In addition, by incorporating lead chloride in CsPbI3‐xBrx precursor, the perovskite film crystallinity is significantly enhanced and the charge recombination in perovksite is suppressed. As a result, optimized CsPbI3‐xBrx PSCs with a band gap of 1.77 eV exhibit excellent performance with the best VOC as high as 1.25 V and an efficiency of 18.64%. Meanwhile, a high photostability with a less than 6% efficiency drop is achieved for CsPbI3‐xBrx PSCs under continuous 1 sun equivalent illumination over 1000 h. The power conversion efficiency of inorganic perovskite solar cells (PSCs) is still low compared with hybrid PSCs. The use of lithium fluoride on SnO2 and PbCl2 additive in perovskite is reported for reducing the charge recombination; 18.64% efficiency of CsPbI3–xBrx solar cells is demonstrated; and the devices show over than 1000 h light soaking stability.