Efficient and Stable Carbon-Based Hole-Transport-Layer-Free CsPbI<sub>2</sub>Br Solar Cells by Adding Trace Amounts of Yttrium Acetate into the Photoactive Layer
Xueyan Ma, Hongbo Tong, Wenxuan Li, Hai Liu, Xiaoyang Liu, Guodong Wan, Yali Li, Yujun Fu, Zhenguo Li, Deyan He, Junshuai Li
Abstract
CsPbI 2 Br solar cells are a kind of important inorganic perovskite photovoltaic (PV) device that can serve as the top cells in a tandem configuration or semitransparent PV devices with balanced structural stability and light absorption. However, the issues relating to their power conversion efficiency (PCE) and long-term stability are still severely impeded by uncoordinated Pb 2+ and migratable I – . To effectively passivate the uncoordinated Pb 2+ and meanwhile anchor the migratable I –, herein, we propose a simple strategy by adding yttrium acetate (Y(Ac) 3 ) in the photoactive layer. A leading PCE of 15.53%, together with the notably improved stability and reduced current–voltage hysteresis, indicates the effectiveness of this additive strategy, as demonstrated in the carbon-based hole-transport-layer (HTL)-free CsPbI 2 Br solar cells having a higher performance-to-cost ratio than their conventional counterparts because they abandon the usage of noble metal electrodes and the expensive organic HTLs that are also detrimental to the photoactive layer.