Bisulfate transport in hydrogels for self-healable and transparent thermoelectric harvesting films

Cheolhyun Cho, Byeonggwan Kim, Sienoh Park, Eunkyoung Kim

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6 Citations (Scopus)


A wearable and transparent thermoelectric (TE) hydrogel based on bisulfate transport was demonstrated to record a negative ionic Seebeck coefficient of −25.0 mV K−1, ionic power factor of 9.94 mW m−1 K−2, and an ionic figure of merit of 7.2 at 80% relative humidity and room temperature. The n-type TE hydrogel was made of electronic poly(3,4-ethylenedioxythiophene), ionic poly(2-acrylamido-2-methyl-1-propanesulfonic acid), and biocompatible bisulfate, which was used as a thermally diffusive anion carrier for the first time in TE devices, to realize a soft mixed ionic-electronic conductor. The composition of this hydrogel was precisely controlled by varying the contents of ammonium persulfate and 3,4-ethylenedioxythiophene to afford a transparent and self-healable film that recovered within 15 min after cutting (cut width of ∼35 μm). Bisulfate transport was visualized using an anion detective fluorophore as a tool to intuitively elucidate the Soret effect, in which ion carriers thermodiffuse from hot to cold parts, and to quantify the thermovoltage simultaneously. A flexible band-type TE energy harvester with 20 legs was fabricated to afford a thermovoltage of −2.75 V at a temperature gradient of 5.5 K, and the harvested energy was used to operate a light-emitting diode for the first time in an organic TE module with a small temperature gradient (<10 K). Moreover, a colorful wearable band-type module and photothermal all organic TE device were demonstrated to be effective self-powered body-worn TE harvesters under ambient conditions.

Original languageEnglish
JournalEnergy and Environmental Science
Publication statusAccepted/In press - 2022

Bibliographical note

Funding Information:
C. C. and B. K. contributed equally to this work. This research was supported by a National Research Foundation (NRF) grant funded by the Korean government (Ministry of Science, ICT & Future Planning, MSIP) through the Global Research Lab (GRL: 2016K1A1A2912753), the Creative Materials Discovery Program (2018M3D1A1058536), and the Basic Science Research Program (2020R1I1A1A01057070). B. K. thanks the Korea Initiative for fostering University of Research and Innovation Program of NRF (2020M3H1A1077207).

Publisher Copyright:
© 2022 The Royal Society of Chemistry

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution


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