Increasing the thermopower of crown-ether-bridged anthraquinones

Ismael, Ali K. and Grace, Iain and Lambert, Colin J. (2015) Increasing the thermopower of crown-ether-bridged anthraquinones. Nanoscale, 7 (41). pp. 17338-17342. ISSN 2040-3364

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Abstract

We investigate strategies for increasing the thermopower of crown-ether-bridged anthraquinones. The novel design feature of these molecules is the presence of either (1) crown-ether or (2) diaza-crown-ether bridges attached to the side of the current-carrying anthraquinone wire. The crown-ether side groups selectively bind alkali-metal cations and when combined with TCNE or TTF dopants, provide a large phase-space for optimising thermoelectric properties. We find that the optimum combination of cations and dopants depends on the temperature range of interest. The thermopowers of both 1 and 2 are negative and at room temperature are optimised by binding with TTF alone, achieving thermpowers of -600 mu V K-1 and -285 mu V K-1 respectively. At much lower temperatures, which are relevant to cascade coolers, we find that for 1, a combination of TTF and Na+ yields a maximum thermopower of -710 mu V K-1 at 70 K, whereas a combination of TTF and Li+ yields a maximum thermopower of -600 mu V K-1 at 90 K. For 2, we find that TTF doping yields a maximum thermopower of -800 mu VK-1 at 90 K, whereas at 50 K, the largest thermopower (of -600 mu V K-1) is obtain by a combination TTF and K+ doping. At room temperature, we obtain power factors of 73 mu W m(-1) K-2 for 1 (in combination with TTF and Na+) and 90 mu W m(-1) K-2 for 2 (with TTF). These are higher or comparable with reported power factors of other organic materials.

Item Type:
Journal Article
Journal or Publication Title:
Nanoscale
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2500
Subjects:
ID Code:
77424
Deposited By:
Deposited On:
09 Aug 2016 09:44
Refereed?:
Yes
Published?:
Published
Last Modified:
17 Jun 2020 03:29