A. E. Sudheer | Searcharxiv

arXiv2025

Thermoelectric properties of SbXY (X = Se, Te; Y = Br, I) Janus layers

We report a comprehensive investigation of the thermoelectric properties of SbXY (X = Se, Te; Y = Br, I) Janus layers (JL) using spin-polarized first-principles calculations. Ab initio molecular dynamics confirm that the 1T phase ($Pm31$) remains stable up to 1000 K, excluding any phase transitions. The calculated mean-square displacement further evidences the structural robustness. The thermal conductivity is strongly suppressed in Br-containing layers due to enhanced Froehlich interactions between optical and acoustic phonons. Electronic structure calculations reveal indirect band gaps of 1.1 to 1.3 eV, with valence and conduction bands dominated by the $p$-orbitals of halogen/chalcogen and of Sb, respectively. The carrier effective mass highlights anisotropic transport with lighter electrons being more mobile, while holes dominate the power factor, which attains values on the order of mW/mK$^2$. Direction-dependent transport indicates superior thermoelectric performance along the $xx$ direction, with negligible contribution along $yy$. The Figure of Merit reaches 0.6 at 1000 K in hole-doped SbSeBr, demonstrating strong potential for high-temperature applications. Our results reveal that the SbXY JLs, particularly SbSeBr, emerge as promising candidates for next-generation thermoelectric devices at elevated temperatures.

cond-mat.mtrl-sci↗

arXiv2025

Thermoelectric properties of Lead halide Janus layers -- A theoretical investigation

Thermoelectric materials offer a promising route for efficient heat-to-power conversion. In search of materials functional at high and low operating temperatures, we investigate the thermoelectric properties of two-dimensional lead halide Janus layers (JLs) using density functional theory. The electronegativity difference between halides in JLs significantly modulates the electronic structure, particularly the strong Pb-F bonding in PbIF JLs leads to pronounced band curvature and a unique direct bandgap. Estimated through three-phonon interactions, the lattice thermal conductivity is intrinsically low, primarily due to acoustic phonon contributions and suppressed optical phonon transport. The thermoelectric coefficients are enhanced with carrier doping, resulting in figures of merit as high as 8.94 at room temperature and upto 36.31 at elevated temperatures. These findings establish two-dimensional lead halide Janus layers as exceptional candidates for thermoelectric conversion, and the insights into their elemental and electronic characteristics offer a valuable basis for the future design of high-performance lead-based thermoelectric materials.

cond-mat.mtrl-sci↗