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The critical role of composition-dependent intragrain planar defects in the performance of MA1xFAxPbI3 perovskite solar cells


Perovskite solar cells show excellent power conversion efficiencies, long carrier diffusion lengths and low recombination rates. This encourages a view that intragrain defects are electronically benign with little impact on device performance. In this study we varied the methylammonium (MA)/formamidinium (FA) composition in MA1xFAxPbI3 (x = 0–1), and compared the structure and density of the intragrain planar defects with device performance, otherwise keeping the device nominally the same. We found that charge carrier lifetime, open-circuit voltage deficit and current density–voltage hysteresis correlate empirically with the density and structure of {111}c planar defects (x = 0.5–1) and {112}t twin boundaries (x = 0–0.1). The best performance parameters were found when essentially no intragrain planar defects were evident (x = 0.2). Similarly, reducing the density of {111}c planar defects through MASCN vapour treatment of FAPbI3 (x ≈ 1) also improved performance. These observations suggest that intragrain defect control can provide an important route for improving perovskite solar cell performance, in addition to well-established parameters such as grain boundaries and interfaces.

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Fig. 1: Microstructural characteristics of MA1xFAxPbI3.
Fig. 2: Material characterizations and device properties.
Fig. 3: Schematics of the proposed {111}c twinning structure in MA1xFAxPbI3.
Fig. 4: Ion migration activation energy in MA1xFAxPbI3 films.

Data availability

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


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This work was financially supported by the National Natural Science Foundation of China (NSFC 91963209) and the Australian Government through the Australian Renewable Energy Agency and the ARC Discovery Grants DP150104483 and DP200103070. W.L., M.U.R., U.B. and Y.-B.C. acknowledge the support from the Australian Centre for Advanced Photovoltaics. The authors acknowledge use of facilities within the Monash Centre for Electron Microscopy, a node of Microscopy Australia, and the Monash X-Ray Platform. M.U.R. and W.L. are grateful to L. Bourgeois for expert advice on the operation of the JEOL 2100F transmission electron microscope. W.L. acknowledges support from the National Natural Science Foundation of China (NSFC 51802241) and the Fundamental Research Funds for the Central Universities (WUT: 2019IVB055 and 2019IVA066). Y.Z. was supported by the Hong Kong Research Grants Council (Project no. 15305020) and a Hong Kong Polytechnic University grant (Project no. ZVRP).

Author information




W.L., M.U.R. and Y.Z. contributed equally to this work. W.L., M.U.R., U.B., Y.-B.C. and J.E. conceived and designed the experiments. W.L. and M.U.R. carried out sample preparation. W.L. and M.U.R. performed the electron microscopy, and W.L., M.U.R., Y.Z. and J.E. analysed the data. W.L., Y.Y. and C.Y. carried out the temperature-dependent conductivity tests and data analysis. W.L. is grateful to R. Zhu from Oxford Instruments for operation of the conductive atomic force microscope. W.L., M.U.R., Y.Z. and J.E. wrote the manuscript. All authors contributed to the discussion of the results and revision of the manuscript.

Corresponding authors

Correspondence to Yi-Bing Cheng or Udo Bach or Joanne Etheridge.

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Supplementary Figs. 1–26, Notes 1–7 and Tables 1–4.

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Li, W., Rothmann, M.U., Zhu, Y. et al. The critical role of composition-dependent intragrain planar defects in the performance of MA1xFAxPbI3 perovskite solar cells. Nat Energy 6, 624–632 (2021).

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