Abstract
Perovskite/silicon tandem solar cells have emerged as promising candidates for next-generation photovoltaic technology owing to their ultrahigh power conversion efficiency (PCE)1,2,3. However, the mechanical stress generated during repeated environmental stress cycles remains a critical challenge for flexible perovskite/silicon tandem solar cells, leading to interfacial delamination and device degradation. Here we propose a dual-buffer-layer strategy with a stress-release mechanism to synergistically mitigate ion bombardment during subsequent sputtering deposition and enhance interfacial adhesion while preserving efficient charge extraction. The loose SnOx buffer layer, engineered by adjusting the purging time of atomic layer deposition (ALD), can dissipate strain energy, whereas the compact SnOx layer can ensure robust electrical contact. On the basis of this dual-buffer layer, the flexible tandem solar cell, constructed on a 60-micron-thick ultrathin silicon bottom cell, achieves a certified PCE of 33.4% on 1-cm2 area and a certified PCE of 29.8% on a wafer-sized area of 260-cm2 with a power-per-weight of up to 1.77 W g−1. The modified tandem solar cells demonstrate good durability, retaining more than 97% of their initial PCEs after 43,000 bending cycles under a maximum curvature radius of around 40 mm in air and around 97% after thermal cycling testing (−40 °C to 85 °C) for 250 cycles.
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All data are available in the main text or supplementary materials. The data that support the findings of this study are available from the corresponding authors on request. Source data are provided with this paper.
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Acknowledgements
This work was supported by the National Key Research and Development Program of China (2024YFB3817305), the National Natural Science Foundation of China (no. 62474122, U24A2063), the Key Basic Research Program of Jiangsu Province (no. BK20243031), the Gusu Innovation and Entrepreneurship Leading Talent Program (ZXL2024389), the Special Project for the Integration of ‘Two Chains’ in Shaanxi Province (2023-LL-QY-16), Key Research and Development Program of Shaanxi Province (2025GH-YBXM-011), the Suzhou Key Core Technologies Project (SYG2024146) and Innovative and Entrepreneurial Talent Projects of Qin Chuang Yuan in Shaanxi Province (QCYRCXM-2023-197, QCYRCXM-2023-002).
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Contributions
Conceptualization: Z.F., L.D., Y. Yang, H.L. and J.L. Fabricated and optimized the perovskite/silicon tandem solar cells: Z.F., L.D., Y. Yang, S.X., L.J., Hua Zhang., C.L., Y.Q., Y.H., X.G., B. Li, B. Liu, S.J., W.L. and W.D. Fabricated and optimized the silicon bottom cells: H.C., H.L., X.W., F.Z., Y. Long, X.R. and M.Q. Conducted the XPS/UPS and AFM measurements: Z.F., Z.R., L.N., Huimin Zhang, Y. Yin, D.Y. and S.X. Conducted the stability and bending measurements: Z.F., L.D., H.C., H.L. and Y.X. Conducted the TEM measurements: W.W. and Y. Lu. Funding acquisition: Z.L., X.X., M.Q., B.H., J.L. and X.Z. Writing – original draft: J.L., Z.F., L.D., M.Q. and X.Z. Writing – review and editing: J.L., Z.F., L.D., M.Q. and X.X.
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L.D., Y. Yang, X.G., H.L., H.C., X.W., Y. Long, W.L., F.Z., S.X., L.J., C.L., B. Li, B. Liu, S.J., W.D., Hua Zhang, Y.Q., X.R., Y.X., Y.H., Z.L., X.X., M.Q. and B.H. are employees of LONGi company. All of the other authors declare no competing interests.
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Extended data figures and tables
Extended Data Fig. 1 Process pressure parameters and deposition rate of the SnOx layer by ALD.
a–e, Process pressure as a function of time using different purging times. f, Thickness of the deposited SnOx layers as a function of ALD cycles. The fitted average rates for 10 s and 2 s are 1.5 Å per cycle and 2.3 Å per cycle, respectively.
Extended Data Fig. 2 Tape peeling test on different samples after TCO deposition.
a, PVSK/C60/compact SnOx/TCO sample. b, PVSK/C60/loose SnOx/TCO sample. c, PVSK/C60/compact SnOx/loose SnOx/TCO sample. d, PVSK/C60/loose SnOx/compact SnOx/TCO sample. For each sample, the work of adhesion as a function of displacement at two different locations is given, with the corresponding optical photographs shown underneath.
Extended Data Fig. 3 Water immersion tests.
a, XRD patterns of the samples with regulated SnOx buffer layers under different purging times. b, XRD patterns of the samples after water immersion test for 20 min. c, Tested sample structure. d, Photos of the sample surface after H2O immersion test based on different SnOx layers, fabricated with different purging times ranging from 1 s to 10 s.
Extended Data Fig. 4 Box plots of performance parameters for 1-cm2 perovskite/silicon tandem solar cells based on different ALD dual-buffer layers.
a, Three types of bilayer structure for performance comparison. b, Box plots of PCE, Voc, FF and Jsc for perovskite/silicon tandem solar cells with different SnOx layers.
Extended Data Fig. 5 Theoretical limit of single-junction silicon solar cells as a function of wafer thicknesses under a standard AM 1.5G spectrum.
a–d, The calculations were performed using a self-written MATLAB program. The intrinsic radiative and Auger recombination parameterizations are obtained following the literature37,38. The optical absorption is determined by the ideal Lambertian light-trapping model. Defect-related (Shockley–Read–Hall, SRH) lifetime τn = τp = 40 ms is assumed. The ideal interface and the interface recombination with Jo = 5 fA cm−2 are both considered for comparison.
Extended Data Fig. 6 Theoretical limit of single-junction silicon solar cells as a function of wafer thicknesses under a filtered AM 1.5G spectrum.
a, Comparison of AM 1.5G spectrum filtered by perovskite top cell and standard AM 1.5G spectra. b–e, Calculated photovoltaic parameters.
Extended Data Fig. 7 Device performance of the single-junction silicon solar cells based on different silicon wafer thicknesses.
a, Photovoltaic parameter statistics, measured under 1-sun illumination. b,c, EQE and reflectance curves of the single-junction silicon solar cells.
Extended Data Fig. 8 I–V curves of the perovskite/silicon tandem.
In-house I–V curves of the best-performing perovskite/silicon tandem using 60-μm M6-sized silicon wafer.
Extended Data Fig. 9 I–V curves and photovoltaic parameters of single-junction perovskite devices.
a,b, I–V curves and extracted PV parameters and series resistance (RS) for the small-area (about 1 cm2, a) and large-area (about 261 cm2, b) single-junction perovskite devices on textured conductive silicon substrates.
Extended Data Fig. 10 Mechanical tester for bending durability tests.
A motor is used for automatic bending testing, with each cycle taking 5 s. The test lasted for more than 60 h and was executed over 43,000 cycles.
Supplementary information
Supplementary Information
This Supplementary Information file contains Supplementary Text, Supplementary Figs. 1–21, Supplementary Tables 1–3 and Supplementary References.
Supplementary Video 1
Optical video of the cyclic bending fatigue testing of flexible perovskite/silicon tandem solar cell.
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Fang, Z., Ding, L., Yang, Y. et al. Flexible perovskite/silicon tandem solar cell with a dual-buffer layer. Nature 649, 65–72 (2026). https://doi.org/10.1038/s41586-025-09835-w
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DOI: https://doi.org/10.1038/s41586-025-09835-w
