Vapor-assisted deposition of highly efficient, stable black-phase FAPbI <sub>3</sub> perovskite solar cells
Haizhou Lu, Yuhang Liu, Paramvir Ahlawat, Aditya Mishra, Wolfgang Tress, Felix T. Eickemeyer, Yingguo Yang, Fan Fu, Zaiwei Wang, Claudia E. Avalos, Brian Carlsen, Anand Agarwalla, Xin Zhang, Xiaoguo Li, Yiqiang Zhan, Shaik M. Zakeeruddin, Lyndon Emsley, Ursula Röthlisberger, Li‐Rong Zheng, Anders Hagfeldt, Michaël Grätzel
Abstract
Moving a perovskite into the black The bandgap of the black α-phase FAPbI 3 (where FA is formamidinium) is nearly ideal for solar cells, but it is unstable with respect to the photoinactive yellow δ-phase. Lu et al. found that a film of the yellow phase was converted to a highly crystalline black phase by vapor exposure to methylammonium thiocyanate at 100°C, and it retained this structure after 500 hours at 85°C. Solar cells fabricated with this material had a power conversion efficiency of more than 23%. After 500 hours under maximum power tracking and a period of dark recovery, 94% of the original efficiency was retained. Science , this issue p. eabb8985