Janus ?-PdXY (X/Y = S, Se, Te) materials with high anisotropic thermoelectric performance
No Thumbnail Available
Date
2023-02-21T00:00:00
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Society of Chemistry
Abstract
Two-dimensional (2D) materials have garnered considerable attention as emerging thermoelectric (TE) materials owing to their unique density of states (DOS) near the Fermi level. We investigate the TE performance of Janus ?-PdXY (X/Y = S, Se, Te) monolayer materials as a function of carrier concentration and temperature in the mid-range from 300 to 800 K by combining density functional theory (DFT) and semi-classical Boltzmann transport theory. The phonon dispersion spectra and AIMD simulations confirm their thermal and dynamic stability. The transport calculation results reveal the highly anisotropic TE performance of both n and p-type Janus ?-PdXY monolayers. Meanwhile, the coexistence of low phonon group velocity and a converged scattering rate leads to a lower lattice thermal conductivity (Kl) of 0.80 W mK?1, 0.94 W mK?1, and 0.77 W mK?1 along the y-direction for these Janus materials, while the high TE power factor is attributed to the high Seebeck coefficient (S) and electrical conductivity, which are due to the degenerate top valence bands of these Janus monolayers. The combination of lower Kl and a high-power factor at 300 K (800 K) leads to an optimal figure of merit (ZT) of 0.68 (2.21), 0.86 (4.09) and 0.68 (3.63) for p-type Janus PdSSe, PdSeTe and PdSTe monolayers, respectively. To evaluate rational electron transport properties, the effects of acoustic phonon scattering (?ac), impurity scattering (?imp), and polarized phonon scattering (?polar) are included in the temperature-dependent electron relaxation time. These findings indicated that the Janus ?-PdXY monolayers are promising candidates for TE conversion devices. � 2023 The Royal Society of Chemistry.
Description
Keywords
Anisotropy, Carrier concentration, Density functional theory, Electric power factor, Electron transport properties, Phonons, Selenium compounds, Statistical mechanics, Tellurium compounds, Thermal conductivity, Thermoelectricity, Boltzmann transport theory, Densities of state, Density-functional-theory, Dispersion spectra, P-type, Phonon dispersions, Thermo-Electric materials, Thermoelectric material, Thermoelectric performance, Two-dimensional, article, density functional theory, electric conductivity, electron transport, phonon, relaxation time, simulation, thermal conductivity, Monolayers