XTlO (X = K, Rb, Cs): Novel 2D semiconductors with high electron mobilities, ultra-low lattice thermal conductivities and high thermoelectric figures of merit at room temperature

Thermoelectric materials have attracted much attention in recent years because of their potential application prospects in clean energy and waste heat utilization. In this work, we proposed three novel two-dimensional materials, namely KTlO, RbTlO and CsTlO. Based on the state-of-the-art first principles calculation methods, we found that the three monolayers shown high stability, and with indirect band-gaps of 2.31 eV, 2.27 eV and 2.48 eV, respectively. Their carrier mobilities showed obvious anisotropy, with electron and hole mobilities reaching-103 and-102 cm(2).V-1.s(-1), respectively. In addition, the monolayers shown large Seebeck coefficient (1.75 2.09 mV.K-1), high conductivities (106 108 omega-1m(-1)), as well as power factor (3.19 52.19 mW.K- 2.m(-1)). Also, the monolayers possess ultra-low lattice thermal conductivities of 0.32 0.51 W.m(-1).K-1. As results, their ZT values are up to 1.22, 1.41 and 1.24 at 300 K, respectively. All these properties indicate that monolayer XTlO (X = K, Rb, Cs) have promising applications in the fields of microelectronic devices and thermoelectric materials.

Automated summary

In this work, three novel two-dimensional materials, KTlO, RbTlO, and CsTlO, were proposed for potential applications in thermoelectric materials. Based on first principles calculations, these monolayers were found to possess high stability and suitable band gaps. They exhibited anisotropic carrier mobilities, large Seebeck coefficients, high conductivities, and power factors. The research results indicate that these materials have promising applications in the fields of microelectronic devices and thermoelectric materials.