Thermoelectric Performances of n-Doped Ladder-Type Conjugated Polymers Using Various Viologen Radical Cations

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Thermoelectric Performances of n-Doped Ladder-Type Conjugated Polymers Using Various Viologen Radical Cations
Title:
Thermoelectric Performances of n-Doped Ladder-Type Conjugated Polymers Using Various Viologen Radical Cations
Other Titles:
ACS Applied Polymer Materials
Publication Date:
20 October 2021
Citation:
Tam, T. L. D., Lin, M., Handoko, A. D., & Xu, J. (2021). Thermoelectric Performances of n-Doped Ladder-Type Conjugated Polymers Using Various Viologen Radical Cations. ACS Applied Polymer Materials, 3(11), 5596–5603. https://doi.org/10.1021/acsapm.1c00920
Abstract:
Understanding the dopant–polymer interaction is of interest to the conducting polymer research community due to its influence on charge transport properties and also thermoelectric performance. However, studies on such interactions are often complicated by the change in polymer morphology upon the addition of dopants. Here, we utilized sequential solution doping of a ladder-type poly(benzimidazobenzophenanthrolinedione) (BBL) via viologen radical cation salts. The strong interchain interaction in BBL prevents the infiltration of the viologen radical cations into individual BBL fibrils, thus minimizing the disruption of the polymer morphology. By changing the N-substitution (benzyl or hexyl) and counteranion (chloride or iodide) of the viologen radical cations, the dopant–polymer interaction in such a system was studied. Our results suggest that the anion−π (radical) interaction between the counteranion and BBL (BBL–) is detrimental to the charge transport properties and thermoelectric performance of this system. This anion−π (radical) interaction between the counteranion and BBL (BBL–) is governed by the solution state of the viologen radical cation (tightly bound anion or dimerized with loosely bound anion) during the doping process, which is controlled by the bulkiness of the N-substitution and the Lewis basicity of the counteranion. As a result, BBL doped with benzyl viologen monochloride showed the highest conductivities with reasonably high Seebeck coefficients while BBL doped with hexyl viologen monochloride showed inferior conductivities and Seebeck coefficients.
License type:
Publisher Copyright
Funding Info:
This research / project is supported by the A*STAR SERC - Thermoelectric Materials Program
Grant Reference no. : 1527200019

This research / project is supported by the A*STAR SERC - Thermoelectric Materials Program
Grant Reference no. : 1527200021

This research / project is supported by the A*STAR SERC - Agritech Program
Grant Reference no. : A19D9a0096
Description:
This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Polymer Materials, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsapm.1c00920
ISSN:
2637-6105
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