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A universal close-space annealing strategy towards high-quality perovskite absorbers enabling efficient all-perovskite tandem solar cells


The broad bandgap tunability of organic–inorganic metal halide perovskites enables the fabrication of multi-junction all-perovskite tandem solar cells with ultra-high power conversion efficiencies (PCEs). Controllable crystallization plays a crucial role in the formation of high-quality perovskites. Here we report a universal close-space annealing strategy that increases grain size, enhances crystallinity and prolongs carrier lifetimes in low-bandgap (low-Eg) and wide-bandgap (wide-Eg) perovskite films. By placing the intermediate-phase perovskite films with their faces towards solvent-permeable covers during the annealing process, high-quality perovskite absorber layers are obtained with a slowed solvent releasing process, enabling fabrication of efficient single-junction perovskite solar cells (PVSCs) and all-perovskite tandem solar cells. As a result, the best PCEs of 21.51% and 18.58% for single-junction low-Eg and wide-Eg PVSCs are achieved and thus ensure the fabrication of 25.15% efficiency 4-terminal and 25.05% efficiency 2-terminal all-perovskite tandem solar cells.

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Fig. 1: Scheme of different annealing processes and corresponding film morphology.
Fig. 2: Characterizations of low-Eg perovskite films and PVSCs based on normal annealing, solvent annealing and CSA processes.
Fig. 3: Film quality of wide-Eg perovskites and device performance with normal annealing, solvent annealing and CSA processes.
Fig. 4: Photovoltaic performance of 4-T and 2-T tandem solar cells.

Data availability

The datasets analysed and generated during the current study are included in the paper and its Supplementary Information. Source data are provided with this paper.


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The work was financially supported by the National Key Research and Development Program of China (number 2019YFE0120000), National Natural Science Foundation of China (numbers 61875143, 62005188, 62174112, and 62120106001), Natural Science Foundation of Jiangsu Province (BK20190825), Fundamental Research Funds for the Central Universities (numbers YJ2021157, 2021SCU12057, and YJ201955), the Science and Technology Program of Sichuan Province (numbers 2020JDJQ0030), Engineering Featured Team Fund of Sichuan University (2020SCUNG102) and Engineering Research Center of Digital Imaging and Display, Ministry of Education, Soochow University. F.F. acknowledges funding from the Swiss Federal Office of Energy (SFOE)-BFE (project number SI/501805-01).

Author information

Authors and Affiliations



C.W. and D.Z. conceived the project. C.W. carried out single cell and tandem cell fabrication and characterization. Y.Z., Y.A. and R.H. helped with the fabrication of single-junction wide-Eg PVSCs in both regular and inverted structures. T.M. and J.Z. helped the device fabrication of single-junction low-Eg PVSCs. C.C. did the SEM, X-ray diffraction characterizations of single-junction PVSCs and helped the solvent annealing processes of both low-Eg and wide-Eg perovskite films. S.R. did the PL and TRPL measurements. C.W., F.F., D.Z. and X.L. analysed the data and wrote the manuscript. Y.Z., T.M., Y.A., R.H., J.Z., C.C., S.R. and F.F. helped with the manuscript preparation. All the authors discussed the results and commented on the manuscript. X.L. and D.Z. supervised the project.

Corresponding authors

Correspondence to Fan Fu, Dewei Zhao or Xiaofeng Li.

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The authors declare no competing interests.

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Nature Energy thanks Rohit Prasanna, Atsushi Wakamiya and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–31, Discussions 1–4, Tables 1–5 and References 1–4.

Reporting Summary.

Supplementary Data 1

Supplementary Figs. 1 and 13h and Tables 1 and 3–5.

Source data

Source Data Fig. 2

Source data for Fig. 2c.

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Wang, C., Zhao, Y., Ma, T. et al. A universal close-space annealing strategy towards high-quality perovskite absorbers enabling efficient all-perovskite tandem solar cells. Nat Energy 7, 744–753 (2022).

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