High Conductivity and Electron-Transfer Validation in an n-Type Fluoride-Anion-Doped Polymer for Thermoelectrics in Air
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Zhao, Xingang, Deepa Madan, Yan Cheng, et al. “High Conductivity and Electron-Transfer Validation in an n-Type Fluoride-Anion-Doped Polymer for Thermoelectrics in Air.” Advanced Materials 29, no. 34 (2017): 1606928. https://doi.org/10.1002/adma.201606928.
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This is the peer reviewed version of the following article: Zhao, Xingang, Deepa Madan, Yan Cheng, et al. “High Conductivity and Electron-Transfer Validation in an n-Type Fluoride-Anion-Doped Polymer for Thermoelectrics in Air.” Advanced Materials 29, no. 34 (2017): 1606928. https://doi.org/10.1002/adma.201606928, which has been published in final form at https://doi.org/10.1002/adma.201606928. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited
Abstract
Air-stable and soluble tetrabutylammonium fluoride (TBAF) is demonstrated as an efficient n-type dopant for the conjugated polymer ClBDPPV. Electron transfer from F⁻ anions to the π-electron-deficient ClBDPPV through anion–π electronic interactions is strongly corroborated by the combined results of electron spin resonance, UV–vis–NIR, and ultraviolet photoelectron spectroscopy. Doping of ClBDPPV with 25 mol% TBAF boosts electrical conductivity to up to 0.62 S cm⁻¹, among the highest conductivities that have been reported for solution-processed n-type conjugated polymers, with a thermoelectric power factor of 0.63 µW m⁻¹ K⁻² in air. Importantly, the Seebeck coefficient agrees with recently published correlations to conductivity. Moreover, the F⁻-doped ClBDPPV shows significant air stability, maintaining the conductivity of over 0.1 S cm⁻¹ in a thick film after exposure to air for one week, to the best of our knowledge the first report of an air-stable solution-processable n-doped conductive polymer with this level of conductivity. The result shows that using solution-processable small-anion salts such as TBAF as an n-dopant of organic conjugated polymers possessing lower LUMO (lowest unoccupied molecular orbital), less than -4.2 eV) can open new opportunities toward high-performance air-stable solution-processable n-type thermoelectric (TE) conjugated polymers.