Abstract
Carbon-based perovskite solar cells (C-PSCs) processed at low temperature are gaining attention due to their enhanced stability and cost-effectiveness. However, these benefits are offset by reduced device performance, primarily stemming from inefficient charge transfer between the hole transport layer (HTL) and the carbon electrode. Here we report the use of graphene oxide functionalized with carboxy groups (GO-COOH) as a dopant for the HTL material 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (Spiro-OMeTAD) to facilitate interfacial charge transfer and immobilize lithium ions to improve both device performance and stability. We demonstrate electron transfer between GO-COOH and Spiro-OMeTAD, where the delocalized electrons in GO-COOH enable p-doping without exposure to oxygen, leading to a strong π–π-conjugated HTL–carbon interface. The formation of Li–C bonds immobilizes the mobile lithium ions, further improving device stability. As a result, the C-PSCs achieve a power conversion efficiency of 23.6%, maintaining 98.7% of their initial performance after 1,000 h of continuous illumination. These results bring the performance of C-PSCs closer to that of devices employing metal electrodes.
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Acknowledgements
We thank S. M. Zakeeruddin and M. Grätzel for their help with the initial phase of preparation of this paper, X. Gao at the Instrumental Analysis Center of Dalian University of Technology for electron microscopy testing and W. Sun (Dalian University of Technology) for surface potential measurements. Y.W. acknowledges support from the National Natural Science Foundation of China (22109019), the Liaoning Provincial Central Guidance Fund for Local S & T Development (Category B of the Youth Science Fund Program: 2025JH6/101000004) and the Fundamental Research Funds for the Central Universities (DUT23RC(3)002). Yantao Shi acknowledges support from the National Natural Science Foundation of China (52272193) and the Fundamental Research Funds for the Central Universities (DUT22LAB602). Z.Z. acknowledges support from the Science Technology and Innovation Committee of Shenzhen Municipality (JCYJ20220818101018038) and a Research Grants Council of Hong Kong Grant (N_CityU102/23, C4005-22Y, C1055-23G and 11306521). G.M. acknowledges support from the Spring City Plan: the High-level Talent Promotion and Training Project of Kunming (2022SCP005) and Yunnan Fundamental Research Projects (202301AT070081). X.W. acknowledges support from the Research Grants Council of the Hong Kong Special Administrative Region, China, through a fellowship award (CityU PDFS2425-1S11).
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Y.W., Yantao Shi and Z.Z. conceived the idea together. Y.W. and X.W. developed the concept and analysed the data. Y.W. and W.L. designed the experiments and characterization measurements. G.M. and H.L. performed and analysed the theoretical DFT calculations. Y.W., W.L., Yanying Shi, Z.T. and L.Z. contributed to the fabrication of high-performance devices. S.W. performed the C-AFM and AFM measurements. Q.L., X.W., B.L. and F.V. helped to draw the illustrations. J.Z. and W.Z. performed the device stability tests. Y.W., W.L. and X.W. wrote the paper with comments from all of the other authors.
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Wang, Y., Li, W., Wu, X. et al. Graphene oxide doping of the hole injection layer enables 23.6% efficiency in perovskite solar cells with carbon electrodes. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01893-8
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DOI: https://doi.org/10.1038/s41560-025-01893-8