Enhanced thermopower in two-dimensional ruthenium dichalcogenides $RuX_2$ (X = S, Se): a first-principles study

TL;DR

This study uses first-principles calculations to demonstrate that two-dimensional ruthenium dichalcogenides exhibit high thermopower and promising thermoelectric performance at elevated temperatures, making them suitable for thermoelectric applications.

Contribution

First-principles analysis of $T^{\'-}RuX_2$ (X=S, Se) reveals their high thermopower and stability, identifying them as promising thermoelectric materials.

Findings

High Seebeck coefficients: 2685 μV/K for RuS2 and 1515 μV/K for RuSe2.

Maximum ZT values of 0.85 and 0.87 at 1200 K.

Stable and mechanically robust $T^{\prime}-RuX_2$ monolayers.

Abstract

Transition metal dichalcogenides (TMDs) have garnered attention for their potential in thermoelectric applications due to their unique electronic properties and tunable bandgaps. In this study, we systematically explore the electronic and thermoelectric properties of $T^{\prime}-RuX_2$ (X = S, Se) using first-principles calculations and semi-classical Boltzmann transport equations. Our findings confirm that $T^{\prime}-RuX_2$ is energetically and mechanically stable, with high thermopower values such that $T^{\prime}-RuS_2$ exhibits a Seebeck coefficient of $2685~\mu V/K$ for hole doping and $2585~\mu V/K$ for electron doping, while $T^{\prime}-RuSe_2$ shows values of $1515~\mu V/K$ and $1533~\mu V/K$ for hole and electron doping, respectively. Both materials exhibit reasonable power factors and $ZT$ values, with p-type $T^{\prime}-RuS_2$ and $T^{\prime}-RuSe_2$ achieving maximum ZT values of 0.85 and 0.87, respectively, at 1200~K along the y-direction. These results highlight $T^{\prime}$-$RuS_2$ and $T^{\prime}$-$RuSe_2$ as promising candidates for high-temperature TMD-based thermoelectric devices.