Zhanfei Zhang: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China.
Jianghu Liang: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China.
Jianli Wang: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China.
Yiting Zheng: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China.
Xueyun Wu: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China.
Congcong Tian: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China.
Anxin Sun: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China.
Zhenhua Chen: Shanghai Synchrotron Radiation Facility (SSRF), Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201800, People's Republic of China.
Chun-Chao Chen: School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, People's Republic of China. c3chen@sjtu.edu.cn.
The complete elimination of methylammonium (MA) cations in Sn-Pb composites can extend their light and thermal stabilities. Unfortunately, MA-free Sn-Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor crystallization, due to the coexistence of mixed intermediate phases. Here, we report an additive strategy for finely regulating the impurities in the intermediate phase of CsFAPbSnI and, thereby, obtaining high-performance solar cells. We introduced d-homoserine lactone hydrochloride (D-HLH) to form hydrogen bonds and strong Pb-O/Sn-O bonds with perovskite precursors, thereby weakening the incomplete complexation effect between polar aprotic solvents (e.g., DMSO) and organic (FAI) or inorganic (CsI, PbI, and SnI) components, and balancing their nucleation processes. This treatment completely transformed mixed intermediate phases into pure preformed perovskite nuclei prior to thermal annealing. Besides, this D-HLH substantially inhibited the oxidation of Sn species. This strategy generated a record efficiency of 21.61%, with a V of 0.88 V for an MA-free Sn-Pb device, and an efficiency of 23.82% for its tandem device. The unencapsulated devices displayed impressive thermal stability at 85 °C for 300 h and much improved continuous operation stability at MPP for 120 h.
