Abstract
Incorporating two-dimensional (2D) perovskite phases at the interfaces of three-dimensional (3D) perovskite solar cells improves device performance. These 2D structures form in the bulk and at interfaces of the perovskite film by adding long-chain ammonium salts into the perovskite, but achieving them exclusively at the buried interface remains challenging. Here we sequentially graft thioglycolic acid and oleylamine onto SnO2 nanoparticles. The strong chemical bond between thioglycolic acid and oleylamine ensures that cation exchange with formamidinium iodide, a perovskite precursor, occurs only during thermal annealing, creating a 2D/3D perovskite structure solely at the bottom interface. This localized 2D layer accelerates 3D phase formation, enhances perovskite crystallization and reduces defect concentration at the interface by over tenfold. The resulting solar cells achieve power conversion efficiencies of 26.19% (certified 26.04%, 0.09 cm2), 23.44% (aperture area of 21.54 cm2, certified 22.68%) and 22.22% (aperture area of 64.80 cm2), respectively.
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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
S.P. acknowledges funding support from the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB1140000), the National Natural Science Foundation of China (52272255, U23A20141), the Young Taishan Scholar Program (tstp20240521), Key R&D Program of Shandong Province (2024SFGC0102) and Qingdao New Energy Shandong Laboratory (QIBEBT/SEI/QNESL S202305). K.W. acknowledges funding support from the National Natural Science Foundation of China (62474142), Key Research and Development Program of Shaanxi Province (2025GH-YBXM-011) and Natural Science Foundation of Shandong Province (ZR2024YQ070). X.W. acknowledges the National Natural Science Foundation of China (22379156). We also thank L. Z. Hao at The Hong Kong Polytechnic University for support with the STEM measurements.
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S.P., S.D.W. and K.W. supervised the project. S.P., Q. Zhao. and K.W. conceived the ideas. Q. Zhao. designed the experiments and conducted the device fabrication and characterization. B.Z. contributed to the module fabrication and stability test and part of the characterization and analyses. W.H. and Z.S. helped with the GIWAXS characterization and analyses. Q. Zhang. and H.W. helped with ultraviolet photoelectron spectroscopy (UPS) and FTIR measurements. C.Z. helped with SEM characterization. X.S. and X.F. contributed to part of the TRPL measurements. C.P. and K.W. carried out transient absorption (TA) measurements. C.G. performed the trap state density and SCLC measurements. K.G. and H.J. contributed to part of the perovskite solar cell measurements. X.W. helped with FTIR and nuclear magnetic resonance measurements and analyses. L.W., S.P. and K.W. participated in all the data analyses. S.P., K.W. and Q. Zhao. wrote the paper, and all authors have given approval to the final version of the manuscript.
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S.P., Q.Z., X.W. and K.G. are the inventors of a patent application (filed in the China National Intellectual Property Administration on 10 November 2025 and accorded as application number 2025116336006) related to preparing carboxylate- and aminyl-ligand-modified tin oxide nanoparticles and its applications in this work. The remaining authors declare no competing interests.
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Zhao, Q., Zhang, B., Hui, W. et al. Buried 2D/3D heterojunction in n–i–p perovskite solar cells through solid-state ligand-exchange reaction. Nat Energy (2026). https://doi.org/10.1038/s41560-026-01980-4
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DOI: https://doi.org/10.1038/s41560-026-01980-4
