Effect of lattice defects on electronic structure and thermoelectric properties of two- dimensional WS2 materials

WS2 is a kind of thermoelectric material with great development potential that is used for thermoelectric power generation and refrigeration. In this study, the NEGF-DFT method was used to study the thermoelectric properties of intrinsic 2D-WS2 and the effects of periodic vacancy or substitution atoms on their electronic structure and thermoelectric properties. The results show that the ZT value of p-type 2D-WS2 is better than that of n-type 2D-WS2. The thermoelectric properties of p-type 2D-WS2 and p-type 2D-WS2 with O-atom replacing S-atom are better than those of the corresponding n-type 2D-WS2, while the thermoelectric properties of n-type 2D-WS2 with periodic defects and n-type 2D-WS2 with Se-atom or Te-atom replacement for S-atom are better than those of the corresponding p-type 2D-WS2. The ZT values of n-type 2D-WS2 with periodic defects, n-type 2D-WS2 with Se-atom replacement for S-atom, and n-type 2D-WS2 with Te-atom replacement for S-atom are 2.973, 3.383, and 3.0413, respectively, which indicates 2D-WS2 with Se-atom replacement for S-atom has the best thermoelectric performance.