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

Qi Cao, Yongjiang Li, Hong Zhang, Jiabao Yang, Jian Han, Ting Xu, Shuangjie Wang, Zishuai Wang, Bingyu Gao, Junsong Zhao, Xiaoqiang Li, Xiaoyan Ma, Shaik Mohammed Zakeeruddin, Wei E.I. Sha, Xuanhua Li, Michael Grätzel