Issue 36, 2024

Effects of loosely bound electrons and electron–phonon interaction on the thermoelectric properties of electrenes

Abstract

The low carrier mobility in conventional two-dimensional materials limits their thermoelectric (TE) applications due to high “density of scatterings”. Electrene, a new type of two-dimensional material has spatially interstitial electrons. These loosely bound electrons with a longer carrier–lattice distance undergo a weaker lattice perturbation, resulting in a higher mobility. Here, we systematically study the effect of loosely bound electrons, electron–phonon interaction, and spin orbital interaction on the TE properties of an electrene, HfI2, via first-principles calculations. We found that the p-type Seebeck coefficient is relatively large compared with those of other 2D materials with small effective mass. The larger hole relaxation time of HfI2 results in high p-type electrical conductivity and power factor compared with n-type ones. It is found that the spin-orbital interaction splits the spin-degenerate bands near the Fermi level inducing a decrease of the bandgap and an increase of electrical conductivity. The electron–phonon interaction also affects the phonon transport which decreases the lattice thermal conductivity by 16% under the n-type doping. Overall, our high-fidelity calculations show that the maximum ZT value of HfI2 reaches 1.12 at a temperature of 1200 K under p-type doping. Our work provides a physical picture of the effects of loosely bound electrons and their interaction with phonons and orbitals on thermoelectric properties, providing suggestions for further design of high-performance 2D thermoelectric materials.

Graphical abstract: Effects of loosely bound electrons and electron–phonon interaction on the thermoelectric properties of electrenes

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Article information

Article type
Paper
Submitted
10 May 2024
Accepted
05 Aug 2024
First published
06 Aug 2024

J. Mater. Chem. C, 2024,12, 14496-14504

Effects of loosely bound electrons and electron–phonon interaction on the thermoelectric properties of electrenes

Y. Zhao, Z. Wang, J. Zhou, C. Zhang, S. Shin and L. Shen, J. Mater. Chem. C, 2024, 12, 14496 DOI: 10.1039/D4TC01927J

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