Decoupling light- and oxygen-induced degradation mechanisms of Sn-Pb perovskites in all perovskite tandem solar cells

Yang Bai, Ruijia Tian, Kexuan Sun, Chang Liu*, Xiting Lang, Ming Yang, Yuanyuan Meng, Chuanxiao Xiao, Yaohua Wang, Xiaoyi Lu, Jingnan Wang, Haibin Pan, Zhenhua Song, Shujing Zhou, Ziyi Ge*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Efficiencies of all-perovskite tandem solar cells are dominantly constrained by the challenges pertaining to defects and stability within tin-lead (Sn-Pb) perovskite sub-cells. On top of the well-studied oxygen oxidation, defects related to iodide and the consequent generation of I2 upon light illumination pose significant degradation risks, leading to Sn2+ → Sn4+ oxidation. To address this, we screen phenylhydrazine cation (PEH+)-based additives of varying polarities, which strongly coordinate with Sn for reinforcing the Sn-I bond, and interacting electrostatically with negatively charged defects (VSn, VFA, ISn, and Ii). The synergistic effects suppress the photo-induced formation of I2 and the subsequent oxidation of Sn-Pb perovskites, circumventing the stability concerns of narrow bandgap (NBG) perovskite solar cells (PSCs) under operational conditions. The reducing agent 2-mercaptobenzimidazole (MBI) was further introduced into the precursor solution, which not only demonstrates strong resistance to oxygen erosion, but also reduces the deep-level defect density of the Sn-Pb perovskites. Consequently, single-junction Sn-Pb cells achieve a champion efficiency of 23.0%. The enhanced light stability allows these cells to retain 89.4% of their initial efficiency after 400 hours of continuous operation, as assessed by tracking the maximum power point (MPP). We further integrated the Sn-Pb perovskite into a two-terminal (2T) monolithic all-perovskite tandem cell and achieved a PCE of 27.9% (27.2% certified). Meanwhile, the encapsulated tandem device maintained 90.3% of its initial PCE after 300 h through MPP tracking. The work offers new ideas for tackling the stability issues related to light-triggered oxidation.

Original languageEnglish
Pages (from-to)8557-8569
Number of pages13
JournalEnergy and Environmental Science
Volume17
Issue number22
DOIs
Publication statusPublished - 2 Aug 2024
Externally publishedYes

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Bai, Y., Tian, R., Sun, K., Liu, C., Lang, X., Yang, M., Meng, Y., Xiao, C., Wang, Y., Lu, X., Wang, J., Pan, H., Song, Z., Zhou, S., & Ge, Z. (2024). Decoupling light- and oxygen-induced degradation mechanisms of Sn-Pb perovskites in all perovskite tandem solar cells. Energy and Environmental Science, 17(22), 8557-8569. https://doi.org/10.1039/d4ee02427c