Precise Control of Crystal Growth for Highly Efficient CsPbI2Br Perovskite Solar Cells
Weijie Chen1, Haiyang Chen1, Guiying Xu1, Rongming Xue1, Shuhui Wang1, Yaowen Li1,3,*（李耀文）,and Yongfang Li1,2,*（李永舫）
1Laboratory of Advanced Optoelectronic Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, uzhou, Jiangsu 215123, People’s Republic of China
2CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
Joule 3, 1--14, January 16, 2019
All-inorganic perovskite solar cells (pero-SCs) are attracting considerable attention due to their promising thermal stability, but their inferior power-conversion efficiency (PCE) and moisture instability are hindering their application. Here, we used a gradient thermal annealing (GTA) method to control the growth of a-CsPbI2Br crystals and then utilized a green anti-solvent (ATS) isopropanol to further optimize the morphology of a-CsPbI2Br film. Through this GTA-ATS synergetic effect, the growth of a-CsPbI2Br crystals could be precisely controlled, leading to a high-quality perovskite film with one-micron average grain size, low root-mean-square of 25.9 nm, and reduced defect density. Pero-SCs based on this CsPbI2Br film achieved a champion scan PCE of 16.07% (stabilized efficiency of 15.75%), which is the highest efficiency reported in all-inorganic pero-SCs. Moreover, the CsPbI2Br pero-SC demonstrates excellent robustness against moisture and oxygen, and maintains 90% of initial PCE after aging 120 hr under 100 mW/cm2 UV irradiation.