Mutual stabilization of hybrid and inorganic perovskites for photovoltaics
Yuheng Li, Ziwei Zheng, Xin Zheng, Xiaoyuan Liu, Yingguo Yang, Yongcheng Zhu, Zaiwei Wang, Xingyu Ren, Mingye Fu, Rui Guo, Jing Guo, Zewen Xiao, Yaoguang Rong, Xiong Li
Abstract
Stabilizing black-phase formamidinium lead triiodide (FAPbI 3 ) is critical for high-performance perovskite solar cells (PSCs). We present a stabilization strategy utilizing co-evaporated cesium lead iodide (CsPbI 3 ) capping layers. Enabled by favorable crystal lattice matching, cubic-phase CsPbI 3 spontaneously forms on FAPbI 3 surfaces, establishing mutual phase stabilization with the underlying black-phase FAPbI 3 . When combined with ammonium salt interface modification, the CsPbI 3 interlayer effectively suppresses the ion (FA + and F-PEA + ) diffusion between the stacked perovskite layers. The FAPbI 3 /CsPbI 3 bilayer structured devices exhibited a certified record reverse-scanning power-conversion efficiency of 27.17% and maintained a stabilized power output efficiency of 26.62%. Remarkably, the cells retain 93.5% of the initial efficiency after 1500 h damp-heat test, and retaining over 94.2% of its maximum PCE after about 1185 h with a linear extrapolation to a T 90 of 2352 h operation under continuous illumination at maximum power point tracking at 85 °C. • Cubic CsPbI 3 capping stabilizes black-phase FAPbI 3 via mutual lattice matching. • Ion diffusion between perovskite layers is suppressed by the CsPbI 3 interlayer. • Achieved certified PCE of 27.17% and 24.88% for small and large area PSCs. • Stable operation with 94.2% PCE retention after 1185 h at 85 °C under 1-sun MPP. • Bilayer 3D/3D perovskite design enables universal efficiency boost across bandgaps.