Lattice Dynamics\nand Thermoelectric Properties of\n2D LiAlTe<sub>2</sub>, LiGaTe<sub>2</sub>, and LiInTe<sub>2</sub> Monolayers

The lattice dynamics and thermoelectric properties of\nmonolayers\nof LiAlTe<sub>2</sub>, LiGaTe<sub>2</sub>, and LiInTe<sub>2</sub> are\ncomprehensively investigated by using density functional theory calculations\ncombined with the solution of the Boltzmann transport equation. At\n300 K, the intrinsic lattice thermal conductivity is determined to\nbe 10.41, 6.02, and 5.77 W/(m·K) for LiAlTe<sub>2</sub>, LiGaTe<sub>2</sub>, and LiInTe<sub>2</sub>, respectively, when spin–orbit\ncoupling effects are included in the harmonic force constants. These\nthermal conductivity values are attributed to the combination of low\nacoustic frequencies and enhanced anharmonic phonon scattering rates.\nFurther analysis reveals that thermal transport in these monolayers\nis dominated by in-plane longitudinal acoustic modes. These monolayers\nare direct band gap semiconductors with high electrical conductivity\nand Seebeck coefficients. The synergistic effect leads to a notably\nhigh power factor, which is especially evident in LiInTe<sub>2</sub> monolayers, ultimately resulting in a <i>ZT</i> value\nof 0.8 at 700 K.