Incorporating Electrochemical Halide Oxidation into Drift-Diffusion Models to Explain Performance Losses in Perovskite Solar Cells under Prolonged Reverse Bias

Luca Bertoluzzi, Jay B. Patel, Kevin A. Bush, Caleb C. Boyd, Ross A. Kerner, Brian C. O'Regan, Michael D. McGehee

Research output: Contribution to journalArticlepeer-review

34 Scopus Citations

Abstract

Partial shading of a solar module can induce a set of cells within the module to operate under reverse bias. Studies have shown that metal halide perovskite solar cells with a wide variety of compositions and contacts exhibit interesting behavior in reverse bias that includes both reversible performance loss and non-reversible degradation. In this paper, an advanced drift-diffusion approach incorporating an electrochemical term to explain the short-circuit, open circuit and fill factor losses that are experimentally measured after prolonged reverse bias is used. It is shown that holes can tunnel into the perovskite due to sharp band bending near the contact, accumulate within the bulk of the perovskite absorber, and trigger the oxidation of halides to form neutral halogens. The density of neutral halogens is much higher in reverse bias because there are hardly any electrons available to reduce the iodine. The resulting halogens act as bulk recombination centers. While the interstitial halogen density does decay when the cell is operated in forward bias, permanent degradation can occur if the iodine diffuses out of the perovskite layer. Finally, the ways in which changing parameters such as the mobile ion density or the series resistance at the contact can influence device performance and stability are discussed.

Original languageAmerican English
Article number2002614
Number of pages9
JournalAdvanced Energy Materials
Volume11
Issue number10
DOIs
StatePublished - 2021

Bibliographical note

Publisher Copyright:
© 2021 Wiley-VCH GmbH

NREL Publication Number

  • NREL/JA-5K00-79170

Keywords

  • degradation
  • photovoltaic operational stability
  • recombination
  • reverse bias
  • solid-state electrochemical reactions

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