Simplified interconnection structure based on C60/SnO2-x for all-perovskite tandem solar cells

Abstract

The efficiencies of all-perovskite tandem devices are improving quickly. However, their complex interconnection layer (ICL) structures—with typically four or more layers deposited by different processes—limit their prospects for applications. Here, we report an ICL in all-perovskite tandem cells consisting merely of a fullerene layer and a SnO2–x (0 < x < 1) layer. The C60 layer is unintentionally n-doped by iodine ions from the perovskite and thus acts as an effective electron collecting layer. The SnO2–x layer, formed by the incomplete oxidization of tin (x = 1.76), has ambipolar carrier transport property enabled by the presence of a large density of Sn2+. The C60/SnO1.76 ICL forms Ohmic contacts with both wide and narrow bandgap perovskite subcells with low contact resistivity. The ICL boosts the efficiencies of small-area tandem cells (5.9 mm2) and large-area tandem cells (1.15 cm2) to 24.4% and 22.2%, respectively. The tandem cells remain 94% of its initial efficiency after continues 1-sun illumination for 1,000 h.

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Fig. 1: Design of C60/SnO2−x structured ICLs for monolithic all-perovskite tandem solar cells.
Fig. 2: Ambipolar property of LT-ALD SnO1.76.
Fig. 3: Optical and electronic properties of LT-ALD SnO1.76 and energy diagram of C60/SnO1.76 ICLs.
Fig. 4: Photovoltaic performance of monolithic all-perovskite tandem solar cells with C60/SnO1.76 ICLs.

Data availability

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

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Acknowledgements

This material is based on work supported by the Office of Energy Efficiency and Renewable Energy (EERE) of the US Department of Energy under Solar Energy Technologies Office (SETO) agreement numbers DE-EE0006709 and DE-EE0008749, and by the Research Opportunities Initiative of the University of North Carolina System.

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J.H. conceived the study. J.H. and Z. Yu designed the experiments. Z. Yu and Z. Yang fabricated the tandem devices and conducted the characterization. Z. Yang optimized the NBG perovskite solar cells. Z.N. studied the electronic structure and characterization of tin oxide. Z.N. and Y.S. performed the Hall effect measurement. B.C. measured the EQE spectra and took the SEM images. Y.L. and H.W. analysed the data. Z.J.Y. and Z.H. verified the JV curves of the tandem device by using their dual-lamp solar simulator. J.H. and Z. Yu wrote the paper, and all authors reviewed the paper.

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Correspondence to Jinsong Huang.

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Yu, Z., Yang, Z., Ni, Z. et al. Simplified interconnection structure based on C60/SnO2-x for all-perovskite tandem solar cells. Nat Energy 5, 657–665 (2020). https://doi.org/10.1038/s41560-020-0657-y

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