Superoxide radical derived metal-free spiro-OMeTAD for highly stable perovskite solar cells

Linfeng Ye, Jiahao Wu, Sergio Catalán-Gómez, Li Yuan, Riming Sun, Ruihao Chen, Zhe Liu, Jose María Ulloa, Adrian Hierro, Pengfei Guo, Yuanyuan Zhou, Hongqiang Wang