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Regulating grain growth via Li2SnS3 interphase in kesterite solar cells with certified efficiencies exceeding 15%

Nature Energy volume 11, pages 460–469 (2026) Cite this article

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Abstract

The selenization reaction process is the key step in determining the quality of Cu2ZnSn(S,Se)4 thin films. Imbalanced migration kinetics of metal ions during selenization led to high concentrations of deep-level defects, resulting in dramatic open-circuit voltage loss. In this work, we reported a Li2SnS3 interphase strategy to modify cation migration paths and balance Zn2+/Sn4+ migration differences. The Li2SnS3 interphase selectively encapsulates the Cu2Sn(S,Se)3 intermediate grains, serving as the rate-determining layer for ion migration. The Zn2+/Sn4+ migration barrier difference in the interphase decreases from 0.41 eV in Cu2Sn(S,Se)3 to 0.21 eV in Li2SnS3, which promotes the formation of larger, uniform, high-crystallinity grains. As a result, device efficiency improves from 13.86% to 15.45% (certified at 15.04%), and open-circuit voltage reaches 602 mV at a bandgap of 1.10 eV.

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Fig. 1: Characterization of the selenization process.
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Fig. 2: Composition and elements distribution of the initial grains.
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Fig. 3: Effect of Li2SnS3 interphase on elemental migration.
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Fig. 4: Electric characterization of the final films.
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Fig. 5: Performance of photovoltaic devices.
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Data availability

The data that support the findings of this study are available within the Article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

This study was supported by the National Natural Science Foundation of China (grant 22405286 to X.F., grant 22279154 to Z.S.), Natural Science Foundation of Shandong Province (grant ZR2024ZD15 to Z.S., grant ZR2024QB320 to X.F.), China Postdoctoral Science Foundation (grant 2024M753351 to X.F.), Postdoctoral Fellowship Program (grant GZB20240781 to X.F.), Taishan Scholars of Shandong Province (grant tsqn202408284 to Z.S.) and the Youth Innovation Promotion Association of Chinese Academy of Sciences (CAS) (grant 2023218 to Z.S.).

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Author notes

  1. These authors contributed equally: Changcheng Cui, Yimeng Li, Hao Wei, Xiaofan Du.

Authors and Affiliations

  1. State Key Laboratory of Photoelectric Conversion and Utilization of Solar Energy, Qingdao New Energy Shandong Laboratory, Qingdao Industrial Energy Storage Research Institute, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Science, Qingdao, People’s Republic of China

    Changcheng Cui, Yimeng Li, Hao Wei, Xiaofan Du, Zhipeng Shao, Zucheng Wu, Shengren Xia, Xiaopeng Feng, Shuping Pang, Xiao Wang & Guanglei Cui

  2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, People’s Republic of China

    Changcheng Cui, Yimeng Li, Hao Wei & Guanglei Cui

  3. Key Laboratory for Special Functional Materials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng, People’s Republic of China

    Dongxing Kou, Zucheng Wu, Shengren Xia & Sixin Wu

  4. National Center of International Research for Hybrid Materials Technology, College of Materials Science and Engineering, Qingdao University, Qingdao, People’s Republic of China

    Sui Mao

  5. Key Laboratory of Organic Electronics and Information Displays, Nanjing University of Posts and Telecommunications, Nanjing, People’s Republic of China

    Hao Xin

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Contributions

G.C. and Z.S. conceived and directed the project. C.C., Y.L. and H.W. performed experiments and data analysis. X.D. performed kinetic simulations of elemental migration. Z.W. and S.X. assisted in the preparation and characterization of kesterite films and in the performance characterization of devices. X.F., S.P., X.W., S.M. and H.X. supported the discussion of the results. D.K. and S.W. commented on the results and provided constructive suggestions. All authors analysed the data. C.C., Y.L., H.W. and X.D. wrote the manuscript. Z.S., D.K., S.W. and G.C. commented and reviewed the manuscript.

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Correspondence to Zhipeng Shao, Dongxing Kou, Sixin Wu or Guanglei Cui.

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Nature Energy thanks Charlotte Platzer Björkman, Kaiwen Sun and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information (download PDF )

Supplementary Figs. 1–31 and Supplementary Tables 1–4.

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Supplementary Data (download XLSX )

Statistical source data for Supplementary Figs. 10, 14 and 30.

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Unprocessed Raman and XRD data.

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Unprocessed TEM-EDS point scan and EELS data.

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Unprocessed migration barrier data.

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Unprocessed PL, PLQY, TPV, DLTS, UPS, KPFM contact potential, C–V and DLCP data.

Source Data Fig. 5 (download XLSX )

Unprocessed J–V and EQE data, statistical device data, integrated JSC from EQE, derivative of EQE versus wavelength.

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Cui, C., Li, Y., Wei, H. et al. Regulating grain growth via Li2SnS3 interphase in kesterite solar cells with certified efficiencies exceeding 15%. Nat Energy 11, 460–469 (2026). https://doi.org/10.1038/s41560-026-01987-x

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