Anisotropic Thermoelectric Materials: Pentagonal PtM (M = S, Se, Te).

We here report a new pentagonal network structure of the PtM (M = S, Se, Te) monolayers with the 2/ (no. 14) space group. The electronic structure and thermoelectric properties of the pentagonal PtM monolayers are calculated through the VASP and BoltzTraP codes. We verify their dynamic and thermodynamic stabilities by calculating their phonon spectra and simulating ab initio molecular dynamics. It is found that the new material belongs to the medium-wide indirect band gap semiconductors from the PBE and HSE06 methods. At 300 K, the lattice thermal conductivities () of the pentagonal PtTe in the and directions are the smallest among these three materials, being 1.77 and 5.17 W/m K, respectively. The anisotropic values (2.60/1.14) in the / direction of the pentagonal PtTe at 300 K are much greater than those of the pentagonal PtSe (1.75/0.82) and the pentagonal PtS (0.58/0.16) at 300 K. Importantly, the p-type pentagonal PtTe also has excellent thermoelectric properties at 600 K, with a value of 5.03 in the direction, indicating that the p-type pentagonal PtTe has a good application potential in the thermoelectric field.