A promising high temperature 2D thermoelectric material: novel single-layer ZrHfS₄

Based on the first-principles calculation and Boltzmann transport theory, we report the discovery of a promising candidate for high-performance two-dimensional (2D) thermoelectric material: the single-layer (1L) ZrHfS₄. Through the first-principles molecular dynamics simulation and phonon calculation, 1L-ZrHfS₄ is predicted to be thermodynamically stable even at high temperatures. In addition, the lattice thermal conductivity of 1L-ZrHfS₄ is calculated to be 10.2 W m^-1 K^-1, which is smaller than that of 2D transition-metal dichalcogenides, such as MoS₂ and WS₂. Notably, considering not only all the transport coefficients but also the relaxation time for both acoustic and optical phonon scattering, the maximum figure of merit (ZT) of 1L-ZrHfS₄ at 1200 K can achieve 1.92 at moderate n-type doping. These findings suggest 1L-ZrHfS₄ as a potential material for efficient thermoelectric energy conversion, particularly in applications requiring high temperature operation.