Extensive studies have focused on improving the operational stability of perovskite solar cells, but few have surveyed the fundamental degradation mechanisms. One aspect overlooked in earlier works is the effect of the atmosphere on device performance during operation. Here we investigate the degradation mechanisms of perovskite solar cells operated under vacuum and under a nitrogen atmosphere using synchrotron radiation-based operando grazing-incidence X-ray scattering methods. Unlike the observations described in previous reports, we find that light-induced phase segregation, lattice shrinkage and morphology deformation occur under vacuum. Under nitrogen, only lattice shrinkage appears during the operation of solar cells, resulting in better device stability. The different behaviour under nitrogen is attributed to a larger energy barrier for lattice distortion and phase segregation. Finally, we find that the migration of excessive PbI2 to the interface between the perovskite and the hole transport layer degrades the performance of devices under vacuum or under nitrogen.
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Financial support from Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) via Germany´s Excellence Strategy – EXC 2089/1 – 390776260 (e-conversion) and via International Research Training Group 2022 Alberta/Technical University of Munich International Graduate School for Environmentally Responsible Functional Materials (ATUMS), as well as from TUM.solar in the context of the Bavarian Collaborative Research Project Solar Technologies Go Hybrid (SolTech) is acknowledged. L.D. thanks the Cambridge Trust and R.G., W.C., L.D., N.L., T.X. and S. Liang acknowledge financial support from the Chinese Scholarship Council (CSC). S.P. acknowledges support from the TUM International Graduate School of Science and Engineering (IGSSE) via the GreenTech Initiative Interface Science for Photovoltaics (ISPV) of the EuroTech Universities, the excellence cluster Nanosystems Initiative Munich (NIM) and the Centre for NanoScience (CeNS). K.J. and S.D.S. acknowledge the Royal Society (UF150033) for funding. We acknowledge the Engineering and Physical Sciences Research Council (EPSRC) for funding (EP/R023980/1). This work was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (HYPERION, grant agreement number 756962).
S.D.S. is a co-founder of Swift Solar. All other authors declare no competing interests.
Peer review information Nature Energy thanks Antonino La Magna, Michael McGehee and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Guo, R., Han, D., Chen, W. et al. Degradation mechanisms of perovskite solar cells under vacuum and one atmosphere of nitrogen. Nat Energy 6, 977–986 (2021). https://doi.org/10.1038/s41560-021-00912-8