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

Zhaojian Xu, Ross A. Kerner, Steven P. Harvey, Kai Zhu, Joseph J. Berry, Barry P. Rand

Research output: Contribution to journalArticlepeer-review

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 Ii+, IX-, and BrX- 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 languageEnglish (US)
Pages (from-to)513-520
Number of pages8
JournalACS Energy Letters
DOIs
StateAccepted/In press - 2022

All Science Journal Classification (ASJC) codes

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry

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