GaInX3 (X = S, Se, Te): Ultra-low thermal conductivity and excellent thermoelectric performance

Abstract

Abstract Seeking intrinsically low thermal conductivity materials is a viable strategy in the pursuit of high-performance thermoelectric materials. Here, by using first-principles calculations and semiclassical Boltzmann transport theory, we systemically investigate the carrier transport and thermoelectric properties of monolayer Janus GaInX 3 (X = S, Se, Te). It is found that the lattice thermal conductivities can reach values as low as 3.07 W⋅m−1⋅K−1, 1.16 W⋅m−1⋅K−1 and 0.57 W⋅m−1⋅K−1 for GaInS3, GaInSe3, and GaInTe3, respectively, at room temperature. This notably low thermal conductivity is attributed to strong acoustic-optical phonon coupling caused by the presence of low-frequency optical phonons in GaInX 3 materials. Furthermore, by integrating the characteristics of electronic and thermal transport, the dimensionless figure of merit ZT can reach maximum values of 0.95, 2.37, and 3.00 for GaInS3, GaInSe3, and GaInTe3, respectively. Our results suggest that monolayer Janus GaInX 3 (X = S, Se, Te) is a promising candidate for thermoelectric and heat management applications.