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Evolution of defects during the degradation of metal halide perovskite solar cells under reverse bias and illumination

Abstract

The efficiency and stability of perovskite solar cells are essentially determined by defects in the perovskite layer, yet their chemical nature and linking with the degradation mechanism of devices remain unclear. Here we uncover where degradation occurs and the underlying mechanisms and defects involved in the performance degradation of p–i–n perovskite solar cells under illumination or reverse bias. Light-induced degradation starts with the generation of iodide interstitials at the interfacial region between the perovskite and both charge transport layers. While we observe trap annihilation of two types of iodide defect at the anode side, we find negatively charged iodide interstitials near the cathode side, which we show to be more detrimental to the solar cell efficiency. The reverse-bias degradation is initialized by the interaction between iodide interstitials and injected holes at the interface between the electron transport layer and the perovskite. Introducing a hole-blocking layer between the layers suppresses this interaction, improving the reverse-bias stability.

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Fig. 1: Degradation of thin single-crystal perovskite solar cell under reverse bias.
Fig. 2: Degradation of polycrystalline thin film perovskite solar cells under reverse bias.
Fig. 3: Identifying the chemical nature of traps in iodide perovskites.
Fig. 4: Improving the stability of perovskite solar cells under reverse bias.
Fig. 5: Degradation mechanism of perovskite solar cells under illumination.

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

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Acknowledgements

This work was supported by the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, Office of Science, within the US Department of Energy. We thank V. Blum in the Department of Mechanical Engineering and Material Science of Duke University for insightful discussions.

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Authors

Contributions

J.H. and Z.N. conceived the idea and designed the experiments. Z.N., H.J., C.F., H.G., S.X., G.Y. and Q.J. fabricated the perovskite polycrystalline thin film solar cells. Z.N. and Y.L. synthesized the perovskite thin single crystals. Z.N. and S.X. carried out the measurements for the devices. Z.Y. performed the ALD for the devices. Y.Y. participated in data analyses and project discussion. Y.D. did the TPC measurement. Z.N. and J.H. wrote the Article, and all authors reviewed it.

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Correspondence to Jinsong Huang.

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Supplementary Figs. 1–26, Notes 1–4, Table 1 and Refs. 1–4.

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Source data point for Fig. 1c.

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Ni, Z., Jiao, H., Fei, C. et al. Evolution of defects during the degradation of metal halide perovskite solar cells under reverse bias and illumination. Nat Energy 7, 65–73 (2022). https://doi.org/10.1038/s41560-021-00949-9

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