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. In PressDubbel 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