Halogen Redox Shuttle Explains Voltage-Induced Halide Redistribution in Mixed-Halide Perovskite Devices

Zhaojian Xu, Ross Kerner, Steven Harvey, Kai Zhu, Joseph Berry, Barry Rand

Research output: Contribution to journalArticlepeer-review

20 Scopus Citations

Abstract

Voltage-induced halide segregation greatly limits the optoelectronic applications of mixed-halide perovskite devices, but a mechanistic explanation behind this phenomenon remains unclear. In this work, we use electron microscopy and elemental mapping to directly measure the halide redistribution in mixed-halide perovskite solar cells with quasi-ion-impermeable contact layers under different bias polarities to find iodide and bromide accumulation at the cathode and anode, respectively. This is consistent with a mechanism based on preferential iodide oxidation at the anode, leading to unbalanced Formula Presented, Formula Presented, and Formula Presented fluxes. Importantly, switching the anode from “inert” Au to “active” Ag prevents segregation because Ag oxidation precludes the oxidation of lattice iodide, which suggests employing redox-active additives as a general strategy to suppress halide segregation. Overall, these results show that halide perovskite devices operate as solid-state electrochemical cells when threshold voltages are exceeded, providing fresh insight to understand the impacts of voltage bias on halide perovskite devices.

Original languageAmerican English
Pages (from-to)513-520
Number of pages8
JournalACS Energy Letters
Volume8
Issue number1
DOIs
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2022 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-84175

Keywords

  • electrochemistry
  • halide peroskites
  • halide segregation
  • phase separation
  • voltage-induced

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