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Inhibition of halide oxidation and deprotonation of organic cations with dimethylammonium formate for air-processed p–i–n perovskite solar cells

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Abstract

The manufacturing of perovskite solar cells under ambient conditions is desirable, yet the efficiency of p–i–n perovskite solar cells fabricated in air still lags behind those made in an inert atmosphere. Here we introduce an ionic pair stabilizer, dimethylammonium formate (DMAFo), into the perovskite precursor solution to prevent the degradation of perovskite precursors. DMAFo inhibits the oxidization of iodide ions and deprotonation of organic cations, improving the crystallinity and reducing defects in the resulting perovskite films. We show the generation of additional p-type defects during ambient air fabrication that suggests the need for improving bulk properties of the perovskite film beyond surface passivation. Upon addition of DMAFo, we demonstrate that the efficiency of inverted p–i–n solar cells based on perovskite layers with 1.53-eV and 1.65-eV bandgaps fabricated under ambient conditions (25–30 °C, 35–50% relative humidity) increases by 15–20%. We achieve a certified stabilized efficiency of 24.72% for the 1.53-eV cell, on a par with state-of-the-art counterparts fabricated in an inert atmosphere.

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Fig. 1: Stabilization of perovskite precursor solution in ambient air with DMAFo.
Fig. 2: Impact of the DMAFo on the perovskite’s crystallization in ambient air.
Fig. 3: Surface and bulk improvements of perovskite films fabricated in ambient air.
Fig. 4: Enhanced p–i–n perovskite solar cells fabricated in ambient air.

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All data generated or analysed during this study are included in the published article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

We acknowledge the staff of the Shanghai Synchrotron Radiation Facility (SSRF, BL14B1, BL14W1 and BL03HB beamline, project number 2020-SSRF-PT-014606), J. Xue (National Synchrotron Radiation Laboratory, University of Science and Technology of China) for helpful discussion and the Anhui Absorption Spectroscopy Analysis Instrument Co. for XAFS measurements and analysis. This work was partially carried out at the Instruments Center for Physical Science, University of Science and Technology of China. Funding: the work was supported by the National Natural Science Foundation of China (number 52172246); Anhui Province Industrial Innovation Project (AHZDCYCX-LSDT2023-09); National Key R&D Program of China (number 2021YFF0501900); the Institute of Energy, Hefei Comprehensive National Science Center (number 21KZS212); the Cornerstone Science Foundation through an XPLORER PRIZE to Jixian Xu and Fundamental research funds for the central universities (WK3430000009).

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Author notes

  1. These authors contributed equally: Hongguang Meng, Kaitian Mao, Fengchun Cai, Kai Zhang.

Authors and Affiliations

  1. Key Laboratory of Precision and Intelligent Chemistry, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, China

    Hongguang Meng, Kaitian Mao, Fengchun Cai, Shaojie Yuan, Tieqiang Li, Zhengjie Zhu, Xingyu Feng, Wei Peng, Jiahang Xu, Yan Gao, Weiwei Chen, Xiaojun Wu & Jixian Xu

  2. Hefei National Research Center for Physical Sciences at the Microscale, Hefei, China

    Kai Zhang & Weiwei Chen

  3. Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo City, China

    Fangfang Cao & Chuanxiao Xiao

  4. Shanghai Synchrotron Radiation Facility (SSRF), Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China

    Zhenhuang Su

  5. Ningbo New Materials Testing and Evaluation Center Co., Ningbo City, China

    Chuanxiao Xiao

  6. Chemical and Biological Engineering, University of Colorado, Boulder, CO, USA

    Michael D. McGehee

  7. Institute of Energy, Hefei Comprehensive National Science Center, Hefei, China

    Jixian Xu

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Contributions

Jixian Xu conceived and directed the project. M.D.M., H.M. and Jixian Xu reviewed the experiment, analysed the data and wrote the manuscript, and all authors discussed the results and commented on the manuscript. H.M. synthesized the ionic liquids, fabricated films/devices and conducted XRD/UV–vis/GIWAXs/PLQY/stability measurements. K.M. and W.P. helped fabricate and characterize the devices. F. Cai performed the device simulations. C.X. and F. Cao conducted KPFM characterizations. Z.S. helped carry out GIWAXS, EXAFS and analyse data. S.Y. and Z.Z. carried out the NMR measurement. X.W., K.Z. and Y.G. performed density functional theory calculations. T.L. and X.F. helped collect and analyse XPS data. Jiahang Xu and W.C. helped synthesize and characterize the ionic liquids.

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Correspondence to Jixian Xu.

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M.D.M. is an adviser to Swift Solar. University of Science and Technology of China (USTC) has filed patents related to the subject matter of this manuscript. The remaining authors declare no competing interests.

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Nature Energy thanks Dong Suk Kim, Min Kim and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. 1–24, Notes 1–10, Tables 1–3 and references.

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Supplementary Data 1

Statistical source data for Supplementary Fig. 13.

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Source Data Fig. 4

Source data for Fig. 4k,m.

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Meng, H., Mao, K., Cai, F. et al. Inhibition of halide oxidation and deprotonation of organic cations with dimethylammonium formate for air-processed p–i–n perovskite solar cells. Nat Energy 9, 536–547 (2024). https://doi.org/10.1038/s41560-024-01471-4

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