Efficient and stable inverted perovskite solar cells with very high fill factors via incorporation of star-shaped polymer

• Published in: Science advances Vol. 7; no. 28
• Main Authors: Cao, Qi, Li, Yongjiang, Zhang, Hong, Yang, Jiabao, Han, Jian, Xu, Ting, Wang, Shuangjie, Wang, Zishuai, Gao, Bingyu, Zhao, Junsong, Li, Xiaoqiang, Ma, Xiaoyan, Zakeeruddin, Shaik Mohammed, Sha, Wei E. I., Li, Xuanhua, Grätzel, Michael
• Format: Journal Article
• Language: English
• Published: American Association for the Advancement of Science 01.07.2021
• Subjects: Applied Physics; Materials Science; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.abg0633

A star-shaped polymer enables inverted perovskite solar cells with efficiency over 22% and a very high fill factor of 0.862. Stabilizing high-efficiency perovskite solar cells (PSCs) at operating conditions remains an unresolved issue hampering its large-scale commercial deployment. Here, we report a star-shaped polymer to improve charge transport and inhibit ion migration at the perovskite interface. The incorporation of multiple chemical anchor sites in the star-shaped polymer branches strongly controls the crystallization of perovskite film with lower trap density and higher carrier mobility and thus inhibits the nonradiative recombination and reduces the charge-transport loss. Consequently, the modified inverted PSCs show an optimal power conversion efficiency of 22.1% and a very high fill factor (FF) of 0.862, corresponding to 95.4% of the Shockley-Queisser limited FF (0.904) of PSCs with a 1.59-eV bandgap. The modified devices exhibit excellent long-term operational and thermal stability at the maximum power point for 1000 hours at 45°C under continuous one-sun illumination without any significant loss of efficiency.