Abstract
Silicon solar cells are essential for sustainable energy but remain limited by efficiency losses, particularly in the fill factor1,2,3. Here we develop a hybrid interdigitated back-contact solar cell that combines advanced all-surface passivation with laser-treated tunnelling contacts. This approach achieves a power conversion efficiency of 27.81%, approaching 95% of the theoretical limit4. By integrating high- and low-temperature processes, we suppress recombination and enhance contact performance, achieving a fill factor of 87.55%—nearly 98% of the theoretical limit. A model links the ideality factor to carrier loss mechanisms, elucidating carrier recombination in both the bulk and the surface and clarifies key fill factor losses owing to recombination. These innovations provide both experimental and theoretical advances towards scalable, high-efficiency silicon photovoltaics.
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All results are presented as figures, with key experimental and simulation parameters reported. Source data (numerical values behind figures) are available upon request; simulations used commercial third-party software.
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Acknowledgements
This work was funded by the National Key R&D Program of China (2022YFB4200104, 2022YFB4200203), the National Natural Science Foundation of China (62034009), the Qinchuangyuan Project of Shaanxi Province (2025QCY-KXJ-189), and the Young Talent Fund of Association for Science and Technology in Shaanxi of China (20230525).
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X.X. and Z.L. conceived of the idea. G.W., M. Yu, H.W., Y. Li, L.X., J. Wei, Y.Y., M. Yang, C.S., L.W., J.C., X.R., F.Y. and M.Q. designed the experiments. M. Yu conceived of and led the development of the laser-induced crystallization technique. H.W., L.X. and G.W. fabricated the cell. X.D., S.Z., T.Y., F.L., Z.H., X.T., Q.T., S.Y., H.Q. and Y. Liu fabricated the devices and participated in data acquisition and result discussion. G.W., H.T. and H. Liu conducted the simulations. C.X. developed the mathematical expression for ideality factor. J. Wang, J.L., B.H., L.C. and L.F. administrated the project. H. Lin, Q.L., P.G. and D.H. provided expertise and supervised the study. G.W., M. Yu and C.X. composed the paper. C.X., P.G. and X.X. revised the paper.
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G.W., M. Yu, H.W., Y. Li, L.X., J. Wei, X.D., S.Z., T.Y., F.L., Y.Y., Z.H., X.T., Q.T., S.Y., H.Q., Y. Liu, M. Yang, C.S., L.W., J.C., X.R., F.Y., M.Q., J. Wang, J.L., B.H., L.C., C.X., L.F., X.X. and Z.L. are employed at LONGi Green Energy Technology Co., Ltd, which holds all associated intellectual property. The other authors declare no competing interests.
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Nature thanks Kean Chern Fong, Kwanyong Seo and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.
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Extended data figures and tables
Extended Data Fig. 1 The complete fabrication process flow of the HIBC solar cell.
The cell fabrication process comprises 14 major steps including Step 1. Wet chemical cleaning 1, Step 2. CVD deposition 1, Step 3. phosphorus diffusion, Step 4. CVD deposition 2, Step 5. laser patterning 1, Step 6. wet chemical cleaning 2, Step 7. CVD deposition 3, Step 8. wet chemical cleaning 3, Step 9. CVD deposition 4, Step 10. laser patterning 2, Step 11. laser patterning 3, Step 12. Physical vapour deposition, Step 13. isolation, and Step 14. Metallization.
Extended Data Fig. 2 Optical images of HIBC solar cells.
Top and bottom views of a, 27.81%- and b, 27.63%-efficiency solar cells.
Extended Data Fig. 3 The evaluation of optical parameters and electrical passivation for two designed front structures, including i-a-Si/SiNx stack and AlOx/SiNx stack.
a, Effective lifetime measured on samples symmetrically passivated by i-a-Si/SiNx and AlOx/SiNx stacks on both wafer sides, respectively. b, Recombination prefactor J0 derived from effective lifetime measurements. c, Reflectance curves showing the optical loss for the two designed front structures. d, Measurement of the optical constants (refractive index and extinction coefficient). In the box plot, the top lines, bottom lines, lines in the box and boxes represent maximum values, minimum values, median values and 25-75% distributions, respectively.
Extended Data Fig. 4 Effect of in-situ passivated edge technology (iPET) on HIBC’s photoelectrical performance.
a-c, solar cells’ FF, VOC, and JSC are shown for cells fabricated with and without iPET on wafers with low (1-1.5 Ω cm) and high (8-10 Ω cm) resistivity. In the box plot, the top lines, bottom lines, lines in the box and boxes represent maximum values, minimum values, median values and 25-75% distributions, respectively.
Extended Data Fig. 5 Laser treatment effect on HIBC’s p-type contact through technology computer-aided design simulation.
a, Simulated current flow in pristine and laser-treated pyramidal structures at full scale. b, Band alignment of the ITO/p-a-Si/i-a-Si/n-c-Si stack before and after laser-treated state.
Extended Data Fig. 6 Contact and passivation performance measurements for the n-type and p-type contacts.
a, Current-voltage curves from the transfer line method (TLM) of the n-type contact. b, Linear fitting to extract the contact resistivity of n-type contact. c, Current-voltage curves from TLM of the p-type contact. d, Linear fitting to extract the contact resistivity of p-type contact. e, Effective lifetime profiles with derived recombination parameters.
Extended Data Fig. 7 Scaning electron microscopy images of laser-treated pyramids obtained under different laser conditions.
a, 532 nm nanosecond-laser treated surface. b, 355 nm picosecond-laser treated surface.
Extended Data Fig. 8 Topography, current and surface potential mapping of a TCO/p-a-Si/p-c-Si/i-a-Si/p-a-Si stack.
a, Topography and b, current map measured by conductive atomic force microscopy. c, Topography and d, contact potential difference map measured by Kelvin probe force microscopy.
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Wang, G., Yu, M., Wu, H. et al. Silicon solar cells with hybrid back contacts. Nature 647, 369–374 (2025). https://doi.org/10.1038/s41586-025-09681-w
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DOI: https://doi.org/10.1038/s41586-025-09681-w
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