Self-Repairing Tin-Based Perovskite Solar Cells with a Breakthrough Efficiency Over 11.

Wang, Chengbo; Gu, Feidan; Zhao, Ziran; Rao, Haixia; Qiu, Yaming; Cai, Zelun; Zhan, Ge; Li, Xiaoyue et al. · Adv Mater · 2020

basic_science · Level V

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Abstract

The development of tin (Sn)-based perovskite solar cells (PSCs) is hindered by their lower power conversion efficiency and poorer stability compared to the lead-based ones, which arise from the easy oxidation of Sn<sup>2+</sup> to Sn<sup>4+</sup> . Herein, phenylhydrazine hydrochloride (PHCl) is introduced into FASnI<sub>3</sub> (FA = NH<sub>2</sub> CH  NH<sub>2</sub> <sup>+</sup> ) perovskite films to reduce the existing Sn<sup>4+</sup> and prevent the further degradation of FASnI<sub>3</sub> , since PHCl has a reductive hydrazino group and a hydrophobic phenyl group. Consequently, the device achieves a record power conversion efficiency of 11.4% for lead-free PSCs. Besides, the unencapsulated device displays almost no efficiency reduction in a glove box over 110 days and shows efficiency recovery after being exposed to air, due to a proposed self-repairing trap state passivation process.