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Nanoscopic cross-grain cation homogenization in perovskite solar cells

Nature Nanotechnology volume 20, pages 630–638 (2025)Cite this article

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Abstract

Multiscale cation inhomogeneity has been a major hurdle in state-of-the-art formamidinium–caesium (FA–Cs) mixed-cation perovskites for achieving perovskite solar cells with optimal power conversion efficiencies and durability. Although the field has attempted to homogenize the overall distributions of FA–Cs in perovskite films from both plan and cross-sectional views, our understanding of grain-to-grain cation inhomogeneity and ability to tailor it—that is, spatially resolving the FA–Cs compositional difference between individual grains down to the nanoscale—are lacking. Here we reveal that as fundamental building blocks of a perovskite film, individual grains exhibit cationic compositions deviating from the prescribed ideal composition, severely limiting the interfacial optoelectronic properties and perovskite layer durability. This performance-limiting nanoscopic factor is linked to thermodynamic-driven morphological grooving, leading to a segmented surface landscape. At the grain triple junctions, grooves form nanoscale groove traps that hinder the mixing of solid-state cations across grains and thus retard inter-grain FA–Cs mixing. By rationally modulating the heterointerfacial energies, we reduced the depth of these nanoscale groove traps by a factor of three, significantly improving cation homogeneity. Perovskite solar cells with shallower nanoscale groove traps demonstrate enhanced power conversion efficiencies (25.62%) and improved stability under various standardized international protocols. Our work highlights the significance of resolving surface nano-morphologies for homogeneous properties of perovskites.

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Fig. 1: Cross-grain microstructures.
Fig. 2: Influence of the nano-GT depth on the nanoscale cross-grain cation homogeneity.
Fig. 3: Influence of cross-grain cation homogeneity on film properties.
Fig. 4: PSC performance with cross-grain cation homogenization.

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Data availability

All data that support the main findings are available in the main text and the Supplementary Information. Source data are provided with this paper.

References

  1. Kojima, A., Teshima, K., Shirai, Y. & Miyasaka, T. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. J. Am. Chem. Soc. 131, 6050–6051 (2009).

    Article  CAS  PubMed  Google Scholar 

  2. Jiang, Q. et al. Surface reaction for efficient and stable inverted perovskite solar cells. Nature 611, 278–283 (2022).

    Article  CAS  PubMed  Google Scholar 

  3. Zhao, Y. et al. Inactive (PbI2)2RbCl stabilizes perovskite films for efficient solar cells. Science 377, 531–534 (2022).

    Article  CAS  PubMed  Google Scholar 

  4. Zhou, Y. et al. Advances and challenges in understanding the microscopic structure–property–performance relationship in perovskite solar cells. Nat. Energy 7, 794–807 (2022).

    Article  CAS  Google Scholar 

  5. Min, H. et al. Efficient, stable solar cells by using inherent bandgap of α-phase formamidinium lead iodide. Science 366, 749–753 (2019).

    Article  CAS  PubMed  Google Scholar 

  6. Koh, T. M. et al. Formamidinium-containing metal-halide: an alternative material for near-IR absorption perovskite solar cells. J. Phys. Chem. C 118, 16458–16462 (2014).

    Article  CAS  Google Scholar 

  7. Pellet, N. et al. Mixed-organic-cation perovskite photovoltaics for enhanced solar-light harvesting. Angew. Chem. Int. Ed. 53, 3151–3157 (2014).

    Article  CAS  Google Scholar 

  8. Zheng, X. et al. Improved phase stability of formamidinium lead triiodide perovskite by strain relaxation. ACS Energy Lett. 1, 1014–1020 (2016).

    Article  CAS  Google Scholar 

  9. Wang, Y. et al. Unlocking the ambient temperature effect on FA-based perovskites crystallization by in situ optical method. Adv. Mater. 36, 2307635 (2023).

    Article  Google Scholar 

  10. Li, Z. et al. Stabilizing perovskite structures by tuning tolerance factor: formation of formamidinium and cesium lead iodide solid-state alloys. Chem. Mater. 28, 284–292 (2016).

    Article  Google Scholar 

  11. Yi, C. et al. Entropic stabilization of mixed A-cation ABX3 metal halide perovskites for high performance perovskite solar cells. Energy Environ. Sci. 9, 656–662 (2016).

    Article  CAS  Google Scholar 

  12. Jacobsson, T. J. et al. Unreacted PbI2 as a double-edged sword for enhancing the performance of perovskite solar cells. J. Am. Chem. Soc. 138, 10331–10343 (2016).

    Article  CAS  PubMed  Google Scholar 

  13. Hao, M. et al. Ligand-assisted cation-exchange engineering for high-efficiency colloidal Cs1−xFAxPbI3 quantum dot solar cells with reduced phase segregation. Nat. Energy 5, 79–88 (2020).

    Article  CAS  Google Scholar 

  14. Liang, Z. et al. Homogenizing out-of-plane cation composition in perovskite solar cells. Nature 624, 557–563 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Bai, Y. et al. Initializing film homogeneity to retard phase segregation for stable perovskite solar cells. Science 378, 747–754 (2022).

    Article  CAS  PubMed  Google Scholar 

  16. Huang, J., Xu, P., Liu, J. & You, X.-Z. Sequential introduction of cations deriving large-grain CsxFA1−xPbI3 thin film for planar hybrid solar cells: insight into phase-segregation and thermal-healing behavior. Small 13, 1603225 (2017).

    Article  Google Scholar 

  17. Li, N. et al. Microscopic degradation in formamidinium-cesium lead iodide perovskite solar cells under operational stressors. Joule 4, 1743–1758 (2020).

    Article  CAS  Google Scholar 

  18. Liu, L. et al. A-site phase segregation in mixed cation perovskite. Mater. Rep. Energy 1, 100064 (2021).

    CAS  Google Scholar 

  19. Mullins, W. W. Theory of thermal grooving. J. Appl. Phys. 28, 333–339 (2004).

    Article  Google Scholar 

  20. Zhao, B., Shvindlerman, L. & Gottstein, G. Line tension of grain boundary triple junctions in the copper tricrystals. In TMS 2014: 143rd Annual Meeting & Exhibition 1063–1068 (Springer, 2016).

  21. Hao, M. et al. Flattening grain-boundary grooves for perovskite solar cells with high optomechanical reliability. Adv. Mater. 35, 2211155 (2023).

    Article  CAS  Google Scholar 

  22. Yan, N., Fang, Z., Dai, Z., Feng, J. & Liu, S. Buried interface—the key issues for high performance inverted perovskite solar cells. Adv. Funct. Mater. 34, 2314039 (2024).

    Article  CAS  Google Scholar 

  23. Dong, Q. et al. Interpenetrating interfaces for efficient perovskite solar cells with high operational stability and mechanical robustness. Nat. Commun. 12, 973 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Zhao, L. et al. Enabling full-scale grain boundary mitigation in polycrystalline perovskite solids. Sci. Adv. 8, eabo3733 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Hackl, K., Fischer, F. D. & Svoboda, J. A variational approach to the modelling of grooving in a three-dimensional setting. Acta Mater. 129, 331–342 (2017).

    Article  CAS  Google Scholar 

  26. Mullins, W. W. The effect of thermal grooving on grain boundary motion. Acta Metall. 6, 414–427 (1958).

    Article  Google Scholar 

  27. Saylor, D. M. & Rohrer, G. S. Measuring the influence of grain‐boundary misorientation on thermal groove geometry in ceramic polycrystals. J. Am. Ceram. Soc. 82, 1529–1536 (1999).

    Article  CAS  Google Scholar 

  28. Correa-Baena, J.-P. et al. Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites. Science 363, 627–631 (2019).

    Article  CAS  PubMed  Google Scholar 

  29. Macpherson, S. et al. Local nanoscale phase impurities are degradation sites in halide perovskites. Nature 607, 294–300 (2022).

    Article  CAS  PubMed  Google Scholar 

  30. Guthrey, H. & Moseley, J. A review and perspective on cathodoluminescence analysis of halide perovskites. Adv. Energy Mater. 10, 1903840 (2020).

    Article  CAS  Google Scholar 

  31. Taylor, E. J. et al. Hyperspectral mapping of nanoscale photophysics and degradation processes in hybrid perovskite at the single grain level. Nanoscale Adv. 5, 4687–4695 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  32. Yang, J. et al. Understanding the role of cesium on chemical complexity in methylammonium-free metal halide perovskites. Adv. Energy Mater. 13, 2202880 (2023).

    Article  CAS  Google Scholar 

  33. Chen, J. et al. Efficient and bright white light-emitting diodes based on single-layer heterophase halide perovskites. Nat. Photon. 15, 238–244 (2021).

    Article  CAS  Google Scholar 

  34. Ma, F. et al. Stable α/δ phase junction of formamidinium lead iodide perovskites for enhanced near-infrared emission. Chem. Sci. 8, 800–805 (2017).

    Article  CAS  PubMed  Google Scholar 

  35. Lai, M. et al. Structural, optical, and electrical properties of phase-controlled cesium lead iodide nanowires. Nano Res. 10, 1107–1114 (2017).

    Article  CAS  Google Scholar 

  36. Wang, P. et al. Seed-assisted growth of methylammonium-free perovskite for efficient inverted perovskite solar cells. Small Methods 6, 2200048 (2022).

    Article  CAS  Google Scholar 

  37. Chen, Y. et al. Strain engineering and epitaxial stabilization of halide perovskites. Nature 577, 209–215 (2020).

    Article  CAS  PubMed  Google Scholar 

  38. Saidaminov, M. I. et al. Multi-cation perovskites prevent carrier reflection from grain surfaces. Nat. Mater. 19, 412–418 (2020).

    Article  CAS  PubMed  Google Scholar 

  39. Tao, S. et al. Absolute energy level positions in tin- and lead-based halide perovskites. Nat. Commun. 10, 2560 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  40. Narra, S. et al. Femtosecond transient absorption spectra and dynamics of carrier relaxation of tin perovskites in the absence and presence of additives. J. Phys. Chem. Lett. 11, 5699–5704 (2020).

    Article  CAS  PubMed  Google Scholar 

  41. Yang, L. et al. Record-efficiency flexible perovskite solar cells enabled by multifunctional organic ions interface passivation. Adv. Mater. 34, 2201681 (2022).

    Article  CAS  Google Scholar 

  42. Duan, T. et al. Chiral-structured heterointerfaces enable durable perovskite solar cells. Science 384, 878–884 (2024).

    Article  CAS  PubMed  Google Scholar 

  43. Ren, Y. et al. A spiro-OMeTAD based semiconductor composite with over 100 °C glass transition temperature for durable perovskite solar cells. Nano Energy 81, 105655 (2021).

    Article  CAS  Google Scholar 

  44. Xiao, T. et al. Elimination of grain surface concavities for improved perovskite thin-film interfaces. Nat. Energy 9, 999–1010 (2024).

    Article  CAS  Google Scholar 

  45. Jiang, Q. et al. Towards linking lab and field lifetimes of perovskite solar cells. Nature 623, 313–318 (2023).

    Article  CAS  PubMed  Google Scholar 

  46. Chen, Y. et al. Nuclei engineering for even halide distribution in stable perovskite/silicon tandem solar cells. Science 385, 554–560 (2024).

    Article  CAS  PubMed  Google Scholar 

  47. Zhao, B., Ziemons, A., Shvindlerman, L. S. & Gottstein, G. Surface topography and energy of grain boundary triple junctions in copper tricrystals. Acta Mater. 60, 811–818 (2012).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

Y.Z. acknowledges the research grants from the National Natural Science Foundation of China (NSFC) Excellent Young Scientists Fund (number 52222318), the Hong Kong Research Grant Council (RGC) Early Career Scheme (number 22300221) and General Research Fund (number 12302822), the NSFC/RFC Collaborative Research Scheme (number CRS_HKUST203/23) and the start-up grant from Hong Kong University of Science and Technology (number R9901). Y.Z. also acknowledges the support from the China Merchants Group, particularly China Merchants Testing Certification International Co. Ltd. and China Merchants Research Institute of Advanced Technology Co., Ltd. for translating fundamental research to future technology innovation. J.Y. and M.A. acknowledge the funding from the US National Science Foundation (number 2043205). Y.X. acknowledges the RGC General Research Fund (number 16301720). M.H. and T.X. acknowledge the Hong Kong PhD Fellowship Scheme. T.D. acknowledges the RGC Postdoctoral Fellowship Scheme. X.Z. acknowledges the K. C. Wong Education Foundation. Cathodoluminescence microscopy was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The work at Yale University was supported by the US National Science Foundation (number DMR-2313648). We also acknowledge the experiment assistance from C. Yang and Y. Zhang from ΣLab of The Hong Kong University of Science and Technology (HKUST), S. Guo from The Hong Kong Polytechnic University and M.-G.J. from Southeast University.

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Authors and Affiliations

  1. Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China

    Mingwei Hao, Wenjian Yu, Pengfei Guo, Tianwei Duan & Yuanyuan Zhou

  2. Department of Physics, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China

    Mingwei Hao, Xiangzhao Zhang & Tong Xiao

  3. Institute for Advanced Materials and Manufacturing, Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, USA

    Jonghee Yang & Mahshid Ahmadi

  4. Department of Chemistry, Yonsei University, Seoul, Republic of Korea

    Jonghee Yang

  5. The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA

    Benjamin J. Lawrie

  6. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA

    Benjamin J. Lawrie

  7. Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA

    Linqi Chen & Peijun Guo

  8. Energy Sciences Institute, Yale University, West Haven, CT, USA

    Linqi Chen & Peijun Guo

  9. Department of Mathematics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China

    Yang Xiang

  10. Energy Institute, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China

    Yuanyuan Zhou

Authors
  1. Mingwei Hao
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Contributions

Y.Z. directed the project and conceived the idea. Y.Z. and M.H. co-designed the experiments. Y.Z. and M.A. supervised the project. M.H. performed the materials synthesis, device fabrication and materials/device characterizations. J.Y. and B.J.L. assisted with the CL testing and data analyses. W.Y. assisted in the solar cell fabrication and testing. Pengfei Guo (HKUST) assisted with the device characterization. T.X. assisted with the device stability tests. T.D. performed the XRD measurement and assisted with the mechanical adhesion test. X.Z. performed the theoretical calculations. L.C. and Peijun Guo (Yale) performed the photoluminescence experiments. Y.X. assisted in illustrating the mechanism of cation diffusion between adjacent grains. Y.Z. and M.H. co-drafted the paper, and all co-authors reviewed the paper.

Corresponding authors

Correspondence to Mahshid Ahmadi or Yuanyuan Zhou.

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Nature Nanotechnology thanks Rui Wang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. 1–43, Tables 1 and 2 and Notes 1–3.

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Supplementary Data 1

Source data for Supplementary Figs. 5, 15–18, 20, 23–26, 35 and 39.

Source data

Source Data Fig. 1

Statistical source data of nano-GT depth in Fig. 1f.

Source Data Fig. 4

Statistical source data of VOC in Fig. 4b.

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Hao, M., Yang, J., Yu, W. et al. Nanoscopic cross-grain cation homogenization in perovskite solar cells. Nat. Nanotechnol. 20, 630–638 (2025). https://doi.org/10.1038/s41565-025-01854-y

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