Abstract
Achieving a well-controlled electron-selective layer is critical for the device scalability and performance of perovskite solar cells. While phenyl-C61-butyric acid methyl ester (PCBM) is a promising electron-selective material in inverted perovskite solar cells, its dimerization under environmental stress accelerates the material degradation and complicates producing high-quality PCBM layers, thereby compromising device long-term operational stability and scale-up fabrication. Here we investigated the PCBM molecular stacking on perovskite surfaces, finding that the variability in perovskite surface termination leads to orientation and distribution heterogeneity of the PCBM layer, resulting in undesirable dimerization. To address this, we developed a molecular dopant for suppressing PCBM dimer formation, achieving a certified efficiency of 26.4% in laboratory-scale devices and 25.3% in 1 cm2 devices. Furthermore, these devices maintained 93% of their initial power conversion efficiency after 1,500 h of ageing at 85 °C following the ISOS L-2I protocol.
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The data that support the findings of this study are available from the corresponding authors upon request.
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Acknowledgements
This research was financially supported by the CAS Project for Young Scientists in Basic Research (grant number YSBR-102), the National Key R&D programme of China (grant number 2021YFB3800102) and the National Natural Science Foundation of China (grant numbers 52302324, 52272252, U22A20142 and 62204108). J.Y. acknowledges the support from the Director’s Fund of Hefei Institutes of Physical Science (grants numbers YZJJ-GGZX-2022-01 and YZJJ202304-CX). N.-G.P. acknowledges financial support through grants from the National Research Foundation of Korea, which is funded by the Korean Ministry of Science and ICT under contract NRF-2021R1A3B1076723 (Research Leader Program). J.L. acknowledges the support from the National Natural Science Foundation of China (grant number 22303053). We thank the XPS group and scanning electron microscopy group of the Instruments Center for Physical Science, University of Science and Technology of China for its vigorous support on the work in this article. X.L., J.L. and Y.Z. thank the Center for Computational Science and Engineering at Southern University of Science and Technology and Hoffmann Institute of Advanced Materials at Shenzhen Polytechnic University for providing the computing resources.
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Contributions
Z.L., J.Y. and X.P. conceived the main idea of this work; J.Y., X.P. and N.-G.P. oversaw the administration of this project; J.L., Z.L. and Y.Z. conceptualized and analysed the theoretical study; Z.L., H.X., Z.H. and B.L. fabricated devices and performed photovoltaic measurements; X.L. performed the MD simulations and DFT calculations under the supervision of J.L; Z.L. contributed to or assisted with subsequent experimental characterizations and data analysis. P.Z., Y. Li, J.Z. and J.D. synthesized the perovskite materials and performed the electrical characterizations under supervision of Y.Z. and B.X; W.C. performed optoelectronic characterization under supervision of Z.X; X.W. contributed to the methodology design under supervision of S.Y; Y.L. completed the preparation and testing of large area PSMs under supervision of Y.D. and J.S; S.W. contributed to the ARPR analysis under supervision of L.Y; Y.T. and H.Z. synthesized the additive chemicals under supervision of J.Y. and X.P; X.C. and H.Zh. performed electron microscope analysis; W.L. and Y.Zh. performed the XPS and UPS analysis; S.-U.L. and contributed to the analysis and discussion of activation energy and band alignment. H.L. performed the SFG analysis; T.K. contributed to the discussion of the mechanism; G.X., J.L., Y.Z., J.Y., B.X., X.P. and N.-G.P. secured the funding for this project; Z.L., H.X. and J.Y. wrote the original draft J.L., Y.Z., S.Y., B.X., Z.X., T.K., Y.Y., X.P. and N.-G.P. revised the paper; all authors discussed the results and commented on the paper.
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Extended data
Extended Data Fig. 1 PL spectra.
PL spectra of a, the bare perovskite (PVSK) and separately coated with FIBA (PVSK/FIBA) and b, perovskite films with bare PCBM (Ref) and FIBA-treated PCBM (FIBA).
Extended Data Fig. 2 I-V curves of FTO/PCBM/Ag stack samples.
FIBA concentration varied from 5 wt% to 25 wt%.
Extended Data Fig. 3 Energetic level (Ea’) relative to perovskite VBM.
Energetic level (Ea’) relative to perovskite VBM, as extracted from C-ω-T measurements.
Extended Data Fig. 4 Statistical data of detailed photovoltaic parameters.
Statistical data of detailed photovoltaic parameters, including a, VOC, b, JSC, c, FF and d, PCE of a series devices treated with various FIBA concentrations. Extended Data Fig. 4 presents a box plot showing the mean, the median (as a central line), the 25th to 75th percentile range as the box, and whiskers extending to 1.5 times the interquartile range.
Extended Data Fig. 5 EQE results.
a, EQE results of the reference and FIBA devices. b, Plot of the first-order derivative of EQE measurements, indicating the bandgap of the perovskite materials.
Extended Data Fig. 6 Optical microscopy images.
Optical microscopy images of the a, reference and b, FIBA devices at the metal electrodes region after stability testing under ISOS D-2I. The scale bars represent 100 μm.
Extended Data Fig. 7 Optical microscopy images.
Optical microscopy images of the a, reference and b, FIBA devices at the metal electrodes region after stability testing under ISOS L-3. The scale bars represent 50 μm.
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Supplementary Figs. 1–55, Tables 1–7, Notes 1–5 and references.
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Liang, Z., Xu, H., Huang, Z. et al. Suppression of PCBM dimer formation in inverted perovskite solar cells. Nat. Mater. 25, 267–274 (2026). https://doi.org/10.1038/s41563-025-02368-7
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DOI: https://doi.org/10.1038/s41563-025-02368-7
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