Surface Passivation and Energetic Modification Suppress Nonradiative Recombination in Perovskite Solar Cells

Wei Dong; Wencheng Qiao; Shaobing Xiong; Jianming Yang; Xuelu Wang; Liming Ding; Yefeng Yao; Qinye Bao

doi:10.1007/s40820-022-00854-0

Surface Passivation and Energetic Modification Suppress Nonradiative Recombination in Perovskite Solar Cells

Nanomicro Lett. 2022 Apr 19;14(1):108. doi: 10.1007/s40820-022-00854-0.

Authors

Wei Dong¹, Wencheng Qiao¹, Shaobing Xiong², Jianming Yang², Xuelu Wang¹, Liming Ding³, Yefeng Yao⁴, Qinye Bao^{5

6}

Affiliations

¹ Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, 200241, People's Republic of China.
² School of Physics and Electronic Science, East China Normal University, Shanghai, 200241, People's Republic of China.
³ Center for Excellence in Nanoscience (CAS), Key Laboratory of Nanosystem and Hierarchical Fabrication (CAS), National Center for Nanoscience and Technology, Beijing, 100190, People's Republic of China. ding@nanoctr.cn.
⁴ Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, 200241, People's Republic of China. yfyao@phy.ecnu.edu.cn.
⁵ School of Physics and Electronic Science, East China Normal University, Shanghai, 200241, People's Republic of China. qybao@clpm.ecnu.edu.cn.
⁶ Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006, Shanxi, People's Republic of China. qybao@clpm.ecnu.edu.cn.

Abstract

Surface passivation via post-treatment is an important strategy for improving power conversion efficiency and operational stability of perovskite solar cells. However, so far the interaction mechanisms between passivating additive and perovskite are not well understood. Here, we report the atomic-scale interaction of surface passivating additive 2,2-difluoroethylammonium bromine (2FEABr) on the MAPbI₃. It is found that the bulky 2FEA⁺ cations tend to distribute at film surface, while the Br^- anions diffuse from surface into bulk. A combination of ¹⁹F, ²⁰⁷Pb, and ²H solid-state NMR further reveal the Br^- anions' partial substitution for the I^- sites, the restricted motion of partial MA⁺ cations, and the firmed perovskite lattices, which would improve charge transport and stability of the perovskite films. Optical spectroscopy and ultraviolet photoelectron spectroscopy demonstrate that the 2FEABr induced surface passivation and energetic modification suppress the nonradiative recombination loss. These findings enable the efficiency of the p-i-n structured PSC significantly increasing from 19.44 to 21.06%, accompanied by excellent stability. Our work further establishes more knowledge link between passivating additive and PSC performance.

Keywords: Charge transport; Passivation; Perovskite solar cell; Solid-state NMR.