Abstract
In the fabrication of FAPbI3-based perovskite solar cells, Lewis bases play a crucial role in facilitating the formation of the desired photovoltaic α-phase. However, an inherent contradiction exists in their role: they must strongly bind to stabilize the intermediate δ-phase, yet weakly bind for rapid removal to enable phase transition and grain growth. To resolve this conflict, we introduced an on-demand Lewis base molecule formation strategy. This approach utilized Lewis-acid-containing organic salts as synthesis additives, which deprotonated to generate Lewis bases precisely when needed and could be reprotonated back to salts for rapid removal once their role is fulfilled. This method promoted the optimal crystallization of α-phase FAPbI3 perovskite films, ensuring the uniform vertical distribution of A-site cations, larger grain sizes and fewer voids at buried interfaces. Perovskite solar cells incorporating semicarbazide hydrochloride achieved an efficiency of 26.1%, with a National Renewable Energy Laboratory-certified quasi-steady-state efficiency of 25.33%. These cells retained 96% of their initial efficiency after 1,000 h of operation at 85 °C under maximum power point tracking. Additionally, mini-modules with an aperture area of 11.52 cm2 reached an efficiency of 21.47%. This strategy is broadly applicable to all Lewis-acid-containing organic salts with low acid dissociation constants and offers a universal approach to enhance the performance of perovskite solar cells and modules.
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Data availability
The main data supporting the findings of this study are available in the Article and its Supplementary Information. Additional data are available from the corresponding authors on reasonable request.
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Acknowledgements
This material is based on work supported by the US Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Solar Energy Technologies Office award no. DE-EE0008970 and under Hydrogen and Fuel Cell Technologies Office award nos. DE-EE0008837 and DE-EE0010740, and by the US Air Force Research Laboratory under agreement no. FA9453-19-C-1002. We also acknowledge support on the DFT calculations from the Center for Hybrid Organic-Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, Office of Science, US Department of Energy. The DFT calculations are performed using computational resources sponsored by the US Department of Energy’s Office of Energy Efficiency and Renewable Energy located at the National Renewable Energy Laboratory, also using resources of the National Energy Research Scientific Computing Center (NERSC), a US Department of Energy, Office of Science User Facility, located at Lawrence Berkeley National Laboratory, operated under contract no. DE-AC02-05CH11231 using NERSC award no. BES-ERCAP0017591. This work was partially supported by award no. 70NANB19H005 from the US Department of Commerce, National Institute of Standards and Technology, as part of the Center for Hierarchical Materials Design (CHiMaD). The views expressed in the Article do not necessarily represent the views of the Department of Energy or the US Government.
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Contributions
Y. Yan and S.F. conceived the strategy. Y. Yan supervised the projects and processes. S.F. and N.S. fabricated the devices. S.F., N.S., H.C. and C. Liu conducted the film fabrications and characterizations. X.W. and Y. Xian performed the DFT simulations. A.A. and R.J.E. performed the PL, time-resolved PL and transient photovoltage measurements. Y.L. performed the stability tests. Y. Xu, S.R., Q.Y., Y. Yin and Y.Z. conducted the GIWAXS measurements and data analysis. T.Z. and Haoran Chen collected the XRD data. A.R. and M.M.S. participated in the module fabrications. C. Li, Y. Yang and H.W. measured the TOF-SIMS depth profiles. Z.H. and D.S.G. performed the hyperspectral PL mapping measurements. Z.S. performed the TR-MS measurement. S.F., N.S. and Y. Yan wrote the first draft of the manuscript. S.F., B.C., Z.S., M.G.K., E.H.S. and Y. Yan edited the manuscript. All authors discussed and contributed to the revision of the manuscript.
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Y. Yan and S.F. are authors of a provisional patent (NI2713-004 U, USA) based on this manuscript. The other authors declare no competing interests.
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Nature Nanotechnology thanks Yongzhen Wu, Changduk Yang, Zonglong Zhu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Extended data
Extended Data Fig. 1 TG spectrum of SECl powders (7.591 mg).
The powders decompose at a temperature of around 165.4 °C.
Extended Data Fig. 2 XRD patterns of the films with different SECl concentrations.
The film with 2 mg/mL SECl shows the strongest XRD intensity among all the conditions.
Extended Data Fig. 3 XPS spectra of the Ref and Target films.
In comparison to the Ref, the Target shows an obvious peak of -C = O (a), confirming the existence of SECl in the annealed film. The chemical shifts of the Pb 4f (b) and I 3d (c) binding energies in the Target film reflect the change in the distribution of A-site cations.
Extended Data Fig. 4 XPS depth profiles of the Ref and Target films.
(a), (b) XPS spectra of Rb, Pb, and Cs at different depths in the Ref and Target films. (c), (d) extracted Rb/Pb and Cs/Pb ratios at different depths in the Ref and Target films.
Extended Data Fig. 5 Thermal stability of the perovskite films.
XRD patterns of the aged Ref and Target perovskite films.
Extended Data Fig. 6 J-V curves of the p-i-n PSCs with different SECl concentrations.
The detailed parameters are listed in Extended Data Table 1.
Extended Data Fig. 7 Photovoltaic performances with CBH and CBHCl2 additives.
J-V curves and PV parameters of p-i-n PSCs with two different amounts of CBH and CBHCl2.
Supplementary information
Supplementary Information
Supplementary Figs. 1–32 and Tables 1 and 2.
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Fu, S., Sun, N., Chen, H. et al. On-demand formation of Lewis bases for efficient and stable perovskite solar cells. Nat. Nanotechnol. 20, 772–778 (2025). https://doi.org/10.1038/s41565-025-01900-9
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DOI: https://doi.org/10.1038/s41565-025-01900-9
