Thermoelectric Properties Of The Two-dimensional Material XP₃(X=Ge,As) Via First-principles Calculations

The energy crisis and environmental issues have caused increasing attention to clean energy.The ability of thermoelectric materials to convert waste heat into useful electricity has attracted widespread attention.Asa functional material that converts thermal energy into electrical energy,thermoelectric materials have broad application prospects in the field of industrial waste heat power generation due to their unique properties.However,due to the low thermoelectric conversion efficiency of traditional materials,it restricts the wide application of thermoelectric materials.It is indicated that two-dimensional materials have advantages in thermoelectric and optoelectronic properties.Espcially,a series of reports in thermoelectric research shows that phosphorene compounds may be high-performance thermoelectric materials.In this paper,the thermoelectric properties of two-dimensional phosphorene compound single-layer XP₃(X=GeP₃,AsP₃)are theoretically explored to advance the high-performance new thermoelectric materials.First,by applying the first principles combined with the Boltzmann transport equation,the heat transport properties of single-layer GeP₃and AsP₃materials are systematically studied.Studies have shown that single-layer GeP₃and AsP₃have low lattice thermal conductivity.At 300K,the lattice thermal conductivity of single-layer GeP₃along the armchair direction and the zigzag direction are 1.24 and 1.39 Wm^-1K^-1,respectively,while the corresponding values of single-layer AsP₃are 0.36 and 0.55Wm^-1K^-1,respectively.The difference in thermal conductivity between the two materials is caused by the difference in phonon relaxation time.This extremely low lattice thermal conductivity contains the material's high thermoelectric potential,which motivates us to continue research on the thermoelectric properties of the two materials.Subsequently,at 300K,the maximum value of the S coefficient of the single-layer AsP₃along the armchair direction reached 2800?VK^-1,while the maximum value in the zigzag direction reached 2860?VK^-1,which was much larger than that of the single-layer 1330?VK^-1and 970?VK^-1corresponding to GeP₃.The p-type ZT of single-layer AsP₃reaches 3.32 at 500 K,greater than the ZT(2.32)value of single-layer GeP₃.On the whole,the thermoelectric properties of single-layer GeP₃and AsP₃are both good,which once again confirms the advantages of two-dimensional phosphorus compounds in terms of thermoelectric properties.