2D ferroelectric In2SSeTe with low lattice thermal conductivity and high Seebeck coefficient: A promising thermoelectric material

Abstract

This work investigates the electronic structure and thermoelectric characteristics of the ferroelectric Janus single-layer In₂SSeTe, using first-principles calculations and Boltzmann transport theory. The single-layer In₂SSeTe exhibits a band gap of 2.28 eV, as calculated using the HSE06 functional. Remarkably, it possesses ultra-low lattice thermal conductivity (up to 0.4 WK⁻¹ m⁻¹) and a high Seebeck coefficient (up to 2905 μVK⁻¹). The computed figure of merit is approximately 4.2 at 700 K. Furthermore, it achieves conversion and refrigeration efficiencies of 24 % and 25.7 % of the Carnot limit at 300 K, which underscores its potential for next-generation cooling devices.