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Thermoelectric properties of organic thin films enhanced by π–π stacking

Wang, Xintai; Sangtarash, Sara; Lamantia, Angelo; Dekkiche, Hervé; Forcieri, Leonardo; Kolosov, Oleg V; Jarvis, Samuel P; Bryce, Martin R; Lambert, Colin J; Sadeghi, Hatef; Robinson, Benjamin J

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Authors

Xintai Wang

Sara Sangtarash

Angelo Lamantia

Hervé Dekkiche

Leonardo Forcieri

Oleg V Kolosov

Samuel P Jarvis

Colin J Lambert

Hatef Sadeghi

Benjamin J Robinson



Abstract

Thin films comprising synthetically robust, scalable molecules have been shown to have major potential for thermoelectric energy harvesting. Previous studies of molecular thin-films have tended to focus on massively parallel arrays of discrete but identical conjugated molecular wires assembled as a monolayer perpendicular to the electrode surface and anchored via a covalent bond, know as self-assembled monolayers. In these studies, to optimise the thermoelectric properties of the thin-film there has been a trade-off between synthetic complexity of the molecular components and the film performance, limiting the opportunities for materials integration into practical thermoelectric devices. In this work, we demonstrate an alternative strategy for enhancing the thermoelectric performance of molecular thin-films. We have built up a series of films, of controlled thickness, where the basic units—here zinc tetraphenylporphyrin—lie parallel to the electrodes and are linked via π–π stacking. We have compared three commonly used fabrications routes and characterised the resulting films with scanning probe and computational techniques. Using a Langmuir-Blodgett fabrication technique, we successfully enhanced the thermopower perpendicular to the plane of the ZnTPP multilayer film by a factor of 10, relative to the monolayer, achieving a Seebeck coefficient of −65 μV K−1. Furthermore, the electronic transport of the system, perpendicular to the plane of the films, was observed to follow the tunnelling regime for multi-layered films, and the transport efficiency was comparable with most conjugated systems. Furthermore, scanning thermal microscopy characterisation shows a factor of 7 decrease in thermal conductance with increasing film thickness from monolayer to multilayer, indicating enhanced thermoelectric performance in a π–π stacked junction.

Citation

Wang, X., Sangtarash, S., Lamantia, A., Dekkiche, H., Forcieri, L., Kolosov, O. V., …Robinson, B. J. (2022). Thermoelectric properties of organic thin films enhanced by π–π stacking. JPhys Energy, 4(2), https://doi.org/10.1088/2515-7655/ac55a3

Journal Article Type Article
Acceptance Date Feb 16, 2022
Online Publication Date Feb 23, 2022
Publication Date 2022
Deposit Date May 23, 2022
Publicly Available Date May 23, 2022
Journal Journal of Physics: Energy
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 4
Issue 2
DOI https://doi.org/10.1088/2515-7655/ac55a3

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http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.







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