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.