Excellent thermoelectric properties induced by different contact geometries in phenalenyl-based single-molecule devices

Xuan-Hao Cao,Wu-Xing Zhou,Mengqiu Long,Chang-Yong Chen,Ke-Qiu Chen,Li-Ming Tang

doi:10.1038/s41598-017-11224-x

Xuan-Hao Cao, Wu-Xing Zhou + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-11224-x

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Abstract

We investigated the thermoelectric properties of phenalenyl-based molecular devices by using the non-equilibrium Green’s function method combined with density function theory. The results show that the thermoelectric performance of molecular device can be significantly improved by different contact geometries. The ZT value of the device can reach 1.2 at room temperature, which is two orders of magnitude higher than that of graphene. Moreover, the change of the coupling between molecule and electrodes can also enhance the ZT value. The ZT value can be further optimized to 1.4 at 300 K and 5.9 at 100 K owing to the decrease of electronic thermal conductance and almost unchanged power factor.

Highlights

Thermoelectric materials have the advantage of realizing the mutual transformation of heat and electricity without moving parts or working fluids[1]
Recent computational works show that a high ZT values could be reached in modified graphene nanoribbons (GNRs) which have exploited with quantum coherence effects[29,30,31,32,33,34,35]
The computational results show that M11 have the highest ZT value among M11-M31, which is mainly determined by the electrical transport properties of phenalenyl-based molecular devices, and their thermoelectric performance can be optimized by the coupling between the phenaleny molecule and zigzag GNRs leads

Summary

Introduction

Thermoelectric materials have the advantage of realizing the mutual transformation of heat and electricity without moving parts or working fluids[1]. One approach is to search for electron-crystal−phonon-glass materials[7, 8], whose electrical conductivity is similar to crystal while having a glass-like phonon thermal conductivity, for instance Core-shell Nanowires[9,10,11] and superlattices[12, 13] Another method is to enhance the Seebeck coefficient by the increase of the electrical density of states at the Fermi level in low-dimensional structures[14], such as quantum rings[15], quantum wires[16,17,18,19], antidot arrays[20], nanoribbons[21, 22], nanotubes[23, 24] and single-molecule devices[25, 26]. The computational results show that M11 have the highest ZT value among M11-M31, which is mainly determined by the electrical transport properties of phenalenyl-based molecular devices, and their thermoelectric performance can be optimized by the coupling between the phenaleny molecule and zigzag GNRs leads

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Results

Conclusion