On the Role of Crystal Defects on the Lattice Thermal Conductivity of Monolayer WSe2 (P63/mmc) Thermoelectric Materials by DFT Calculation

TL;DR

This study uses DFT calculations to analyze how various defects in monolayer WSe2 influence its lattice thermal conductivity, revealing significant reductions that could enhance thermoelectric performance.

Contribution

It provides a detailed first-principles analysis of defect-induced thermal conductivity changes in monolayer WSe2, offering insights for optimizing thermoelectric materials.

Findings

Defects can reduce thermal conductivity by up to 86.7%.

Different defect types and locations significantly influence thermal properties.

Atom defect introduction offers a way to tune thermal conductivity.

Abstract

As the energy problem becomes more prominent, researches on thermoelectric (TE) materials have deepened over the past few decades. Low thermal conductivity enables thermoelectric materials better thermal conversion performance. In this study, based on the first principles and phonon Boltzmann transport equation, we studied the thermal conductivities of single-layer WSe2 under several defect conditions using density functional theory (DFT) as implemented in the Vienna Ab-initio Simulation Package (VASP). The lattice thermal conductivities of WSe2 under six kinds of defect states, i.e., PS, SS-c, DS-s, SW-c, SS-e, and DS-d, are 66.1, 41.2, 39.4, 8.8, 42.1, and 38.4 W/(m2K), respectively at 300 K. Defect structures can reduce thermal conductivity up to 86.7% (SW-c) compared with perfect structure. The influences of defect content, type, location factors on thermal properties have been discussed in this research. By introducing atom defects, we can reduce and regulate the thermal property of WSe2, which should provide an interesting idea for other thermoelectric materials to gain a lower thermal conductivity.