Tailored interfaces of unencapsulated perovskite solar cells for >1,000 hour operational stability

Abstract

Long-term device stability is the most pressing issue that impedes perovskite solar cell commercialization, given the achieved 22.7% efficiency. The perovskite absorber material itself has been heavily scrutinized for being prone to degradation by water, oxygen and ultraviolet light. To date, most reports characterize device stability in the absence of these extrinsic factors. Here we show that, even under the combined stresses of light (including ultraviolet light), oxygen and moisture, perovskite solar cells can retain 94% of peak efficiency despite 1,000 hours of continuous unencapsulated operation in ambient air conditions (relative humidity of 10–20%). Each interface and contact layer throughout the device stack plays an important role in the overall stability which, when appropriately modified, yields devices in which both the initial rapid decay (often termed burn-in) and the gradual slower decay are suppressed. This extensively modified device architecture and the understanding developed will lead towards durable long-term device performance.

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Fig. 1: Champion FAMAs device characterization.
Fig. 2: Operational stability of TiO2/FAMACs/HTM/Au devices in ambient conditions.
Fig. 3: ToF–SIMS profiling of operated devices.
Fig. 4: Operational stability of ETL/FAMACs/EH44/MoO x /Al devices in ambient.

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Acknowledgements

This work was supported by the Hybrid Perovskite Solar Cell Program, and B.T.V. was supported by the Organic Photovoltaic Program, which are funded by the US Department of Energy (DOE) under Contract No. DE-AC36-08-GO28308 with the National Renewable Energy Laboratory through the US DOE Solar Energy Technologies Program. J.A.C. was supported by the DOE Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award through the Solar Energy Technologies Office under DOE contract number DE-SC00014664. We thank B. To for the SEM imaging, A. Hicks for assistance with the graphics, and A. Paquin and F. Bélanger of PCAS Canada for supplying 2,7-dibromocarbazole as a precursor for the synthesis of the EH44 HTM used in this study.

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J.A.C, J.M.L. and J.J.B. conceived the project. J.A.C. fabricated the devices and thin-film samples. P.S. designed and performed the photoemission experiments and analysed the data. J.S.T. and T.H.S. synthesized and characterized EH44, and A.S. supervised. J.A.C. and B.J.T.V. performed the stability experiments. S.P.H. performed the ToF–SIMS measurements and S.P.H., J.A.C. and P.S. analysed the ToF–SIMS data. J.M.L. supervised the entire project. J.A.C. wrote the first draft of the paper. All the authors discussed the results and contributed to the writing of the paper.

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Correspondence to Joseph J. Berry or Joseph M. Luther.

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Supplementary Tables 1–4, Supplementary Figures 1–18

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Christians, J.A., Schulz, P., Tinkham, J.S. et al. Tailored interfaces of unencapsulated perovskite solar cells for >1,000 hour operational stability. Nat Energy 3, 68–74 (2018). https://doi.org/10.1038/s41560-017-0067-y

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