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Nature Energy (2026)
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Selenium (Se), the world’s oldest photovoltaic material, is experiencing a resurgence in interest due to its intrinsic wide bandgap of approximately 1.9 eV, making it an ideal photoabsorber for the top cell in tandem solar cells and for indoor photovoltaics. However, the power conversion efficiency of Se solar cells remains constrained by severe non-radiative recombination losses caused by the small grain size (~500 nm) of conventionally thermally annealed Se films. Here we report an illumination-assisted annealing strategy that enables photo-induced crystallization at ambient temperature while suppressing dewetting, followed by subsequent thermal annealing, to fabricate Se films with large grains (~2.7 μm), a low trap-state density (6.9 × 10¹⁴ cm⁻³) and a long carrier lifetime (22.9 ns). The resultant Se solar cells achieve a certified power conversion efficiency of 10.3% with a 1.03 V open-circuit voltage. Unencapsulated devices exhibit negligible performance loss after 1,000 h under maximum power point tracking in ambient conditions.
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This work is supported by the National Key Research and Development Program of China (grant no. 2024YFB4205201 to D-.J-X.), the National Natural Science Foundation of China (grant no. 22375206 to D-.J-X., grant no. 22269019 to Z.L.), the Youth Innovation Promotion Association CAS (grant no. Y2021014 to D-.J-X.) and the Natural Science Foundation of Tianjin (grant no. 22JCYBJC00480 to W.X.).
These authors contributed equally: Xin Wen, Zongbao Li, Wenbo Lu.
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
Xin Wen, Wenbo Lu, Zhouqing Wei, Qingxiang Liu, Xiaoyan An, Mingjie Feng, Jin-Song Hu, Ding-Jiang Xue & Li-Jun Wan
University of Chinese Academy of Sciences, Beijing, China
Xin Wen, Wenbo Lu, Zhouqing Wei, Qingxiang Liu, Xiaoyan An, Jin-Song Hu, Ding-Jiang Xue & Li-Jun Wan
School of Materials Science and Engineering, Wuhan Textile University, Wuhan, China
Zongbao Li
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
Jianjun Li & Gang Liu
College of Chemistry, Nankai University, Tianjin, China
Weiwei Xie
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
Shunchang Liu & Yi Hou
School of Physics, University of Electronic Science and Technology of China, Chengdu, China
Shunchang Liu
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X.W., Z.L. and W.L. prepared films, fabricated devices and characterized them. Z.L. and W.X. performed the DFT calculations and analysed the results. J.L., Z.W., S.L., Q.L., X.A. and M.F. assisted in the material and device characterization. X.W. and D.-J.X. wrote the paper. G.L. provided valuable discussion of the work. J.-S.H. helped with the manuscript preparation. Y.H. and L.-J.W. were involved in the paper writing and revisions, and provided valuable discussion of the work. D.-J.X. conceived the idea and supervised the overall project. All authors read and commented on the manuscript.
Correspondence to Yi Hou, Ding-Jiang Xue or Li-Jun Wan.
The authors declare no competing interests.
Nature Energy thanks Xinwei Wang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Wen, X., Li, Z., Lu, W. et al. Illumination-assisted annealing enables selenium solar cells with open-circuit voltage over 1 V and efficiency exceeding 10%. Nat Energy (2026). https://doi.org/10.1038/s41560-025-01939-x
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