Issue 3, 2020

Radical enhancement of molecular thermoelectric efficiency


There is a worldwide race to find materials with high thermoelectric efficiency to convert waste heat to useful energy in consumer electronics and server farms. Here, we propose a radically new method to enhance simultaneously the electrical conductance and thermopower and suppress heat transport through ultra-thin materials formed by single radical molecules. This leads to a significant enhancement of room temperature thermoelectric efficiency. The proposed strategy utilises the formation of transport resonances due to singly occupied spin orbitals in radical molecules. This enhances the electrical conductance by a couple of orders of magnitude in molecular junctions formed by nitroxide radicals compared to the non-radical counterpart. It also increases the Seebeck coefficient to high values of 200 μV K−1. Consequently, the power factor increases by more than two orders of magnitude. In addition, the asymmetry and destructive phonon interference that was induced by the stable organic radical side group significantly decreases the phonon thermal conductance. The enhanced power factor and suppressed thermal conductance in the nitroxide radical lead to the significant enhancement of room temperature ZT to values ca. 0.8. Our result confirms the great potential of stable organic radicals to form ultra-thin film thermoelectric materials with unprecedented thermoelectric efficiency.

Graphical abstract: Radical enhancement of molecular thermoelectric efficiency

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Article information

Article type
12 Oct 2019
21 Jan 2020
First published
26 Jan 2020
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2020,2, 1031-1035

Radical enhancement of molecular thermoelectric efficiency

S. Sangtarash and H. Sadeghi, Nanoscale Adv., 2020, 2, 1031 DOI: 10.1039/C9NA00649D

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