Strong Suppression of Thermal Conductivity in the Presence of Long Terminal Alkyl Chains in Low-Disorder Molecular Semiconductors.

Autor: Selezneva E; Optoelectronics Group, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK., Vercouter A; Laboratory for Chemistry of Novel Materials, University of Mons, Mons, 7000, Belgium., Schweicher G; Optoelectronics Group, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK., Lemaur V; Laboratory for Chemistry of Novel Materials, University of Mons, Mons, 7000, Belgium., Broch K; Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany., Antidormi A; Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, 08193, Spain., Takimiya K; Emergent Molecular Function Research Group, RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, 351-0198, Japan., Coropceanu V; School of Chemistry and Biochemistry & Center for Organic Photonics and Electronics (COPE), Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA., Brédas JL; School of Chemistry and Biochemistry & Center for Organic Photonics and Electronics (COPE), Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA.; Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721-0088, USA., Melis C; Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, Monserrato (Ca), 09042, Italy., Cornil J; Laboratory for Chemistry of Novel Materials, University of Mons, Mons, 7000, Belgium., Sirringhaus H; Optoelectronics Group, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK.
Jazyk: angličtina
Zdroj: Advanced materials (Deerfield Beach, Fla.) [Adv Mater] 2021 Sep; Vol. 33 (37), pp. e2008708. Date of Electronic Publication: 2021 Aug 03.
DOI: 10.1002/adma.202008708
Abstrakt: While the charge transport properties of organic semiconductors have been extensively studied over the recent years, the field of organics-based thermoelectrics is still limited by a lack of experimental data on thermal transport and of understanding of the associated structure-property relationships. To fill this gap, a comprehensive experimental and theoretical investigation of the lattice thermal conductivity in polycrystalline thin films of dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (Cn-DNTT-Cn with n = 0, 8) semiconductors is reported. Strikingly, thermal conductivity appears to be much more isotropic than charge transport, which is confined to the 2D molecular layers. A direct comparison between experimental measurements (3ω-Völklein method) and theoretical estimations (approach-to-equilibrium molecular dynamics (AEMD) method) indicates that the in-plane thermal conductivity is strongly reduced in the presence of the long terminal alkyl chains. This evolution can be rationalized by the strong localization of the intermolecular vibrational modes in C8-DNTT-C8 in comparison to unsubstituted DNTT cores, as evidenced by a vibrational mode analysis. Combined with the enhanced charge transport properties of alkylated DNTT systems, this opens the possibility to decouple electron and phonon transport in these materials, which provides great potential for enhancing the thermoelectric figure of merit ZT.
(© 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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