Electrically Programmed Doping Gradients Optimize the Thermoelectric Power Factor of a Conjugated Polymer
Artikel i vetenskaplig tidskrift, 2024

Functionally graded materials (FGMs) are widely explored in the context of inorganic thermoelectrics, but not yet in organic thermoelectrics. Here, the impact of doping gradients on the thermoelectric properties of a chemically doped conjugated polymer is studied. The in-plane drift of counterions in moderate electric fields is used to create lateral doping gradients in films composed of a polythiophene with oligoether side chains, doped with 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4TCNQ). Raman microscopy reveals that a bias voltage of as little as 5 V across a 50 µm wide channel is sufficient to trigger counterion drift, resulting in doping gradients. The effective electrical conductivity of the graded channel decreases with bias voltage, while an overall increase in Seebeck coefficient is observed, yielding an up to eight-fold enhancement in power factor. Kinetic Monte Carlo simulations of graded films explain the increase in power factor in terms of a roll-off of the Seebeck coefficient at high electrical conductivities in combination with a mobility decay due to increased Coulomb scattering at high dopant concentrations. Therefore, the FGM concept is found to be a way to improve the thermoelectric performance of not yet optimally doped organic semiconductors, which may ease the screening of new materials as well as the fabrication of devices.

functionally graded materials

chemical doping

organic thermoelectrics

counterion drift

conjugated polymer

Författare

Jian Liu

Chinese Academy of Sciences

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Mariavittoria Craighero

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Vandna Kumari Gupta

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Dorothea Scheunemann

Universität Heidelberg

Sri Harish Kumar Paleti

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Emmy Järsvall

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Youngseok Kim

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Kai Xu

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

Juan Sebastián Reparaz

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

L. Jan Anton Koster

Rijksuniversiteit Groningen

M. Campoy-Quiles

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

M. Kemerink

Universität Heidelberg

Anna Martinelli

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Christian Müller

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Advanced Functional Materials

1616-301X (ISSN) 16163028 (eISSN)

Vol. 34 18 2312549

Dubbel Dopning av Halvledande Polymerer

Vetenskapsrådet (VR) (2018-03824), 2018-01-01 -- 2021-12-31.

Hybrid and Organic Thermoelectric Systems (HORATES)

Europeiska kommissionen (EU) (EC/H2020/955837), 2021-03-01 -- 2025-02-28.

Ämneskategorier

Oorganisk kemi

Materialkemi

Annan elektroteknik och elektronik

Den kondenserade materiens fysik

DOI

10.1002/adfm.202312549

Mer information

Senast uppdaterat

2024-05-11