Hole-limited electrochemical doping in conjugated polymers

Scott T. Keene, Joonatan E.M. Laulainen, Raj Pandya, Maximilian Moser, Christoph Schnedermann, Paul A. Midgley, Iain McCulloch, Akshay Rao, George G. Malliaras

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Simultaneous transport and coupling of ionic and electronic charges is fundamental to electrochemical devices used in energy storage and conversion, neuromorphic computing and bioelectronics. While the mixed conductors enabling these technologies are widely used, the dynamic relationship between ionic and electronic transport is generally poorly understood, hindering the rational design of new materials. In semiconducting electrodes, electrochemical doping is assumed to be limited by motion of ions due to their large mass compared to electrons and/or holes. Here, we show that this basic assumption does not hold for conjugated polymer electrodes. Using operando optical microscopy, we reveal that electrochemical doping speeds in a state-of-the-art polythiophene can be limited by poor hole transport at low doping levels, leading to substantially slower switching speeds than expected. We show that the timescale of hole-limited doping can be controlled by the degree of microstructural heterogeneity, enabling the design of conjugated polymers with improved electrochemical performance.

Original languageEnglish (US)
Pages (from-to)1121-1127
Number of pages7
JournalNature Materials
Volume22
Issue number9
DOIs
StatePublished - Sep 2023
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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