Microscopic Degradation in Formamidinium-Cesium Lead Iodide Perovskite Solar Cells under Operational Stressors

Nengxu Li, Yanqi Luo, Zehua Chen, Xiuxiu Niu, Xiao Zhang, Jiuzhou Lu, Rishi Kumar, Junke Jiang, Huifen Liu, Xiao Guo, Barry Lai, Geert Brocks, Qi Chen, Shuxia Tao*, David P. Fenning, Huanping Zhou

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

159 Citations (Scopus)
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The most important obstacle to widespread use of perovskite solar cells is their poor stability under operational stressors. Here, we systematically monitor the evolution of the photovoltaic performance of perovskite solar cells based on formamidinium-cesium lead iodide (FA0.9Cs0.1PbI3) for 600 h, under a series of controlled operational stressors. Although these devices exhibit reasonable thermal stability, their stability under illumination or stabilized power output (SPO) is far from commercial demands. Synchrotron-based nanoprobe X-ray fluorescence and X-ray-beam-induced current measurements reveal that current-blocking Cs-rich phases segregate during stress tests. The decrease in performance is in line with the increasing density of the Cs-rich clusters in area upon illumination. Theoretical calculations indicate that light-generated carriers provide the thermodynamic driving force for that phase segregation. Our findings correlate device performance to microscopic behavior and atomistic mechanisms and shed light on inhibiting the cation-dependent phase segregation during device operation.

Original languageEnglish
Pages (from-to)1743-1758
Number of pages16
Issue number8
Publication statusPublished - 19 Aug 2020


  • Degradation
  • Density functional theory calculation
  • Mechanism
  • Microscopic characterization
  • Nanoprobe X-ray fluorescence
  • Perovskite solar cells
  • Phase segregation
  • Stability
  • 22/4 OA procedure


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