Engineering High Thermoelectric Performance in Homobilayer WS 2 Through In-plane Rotational Symmetry Breaking

Abstract

In this study, we investigate the influence of in-plane rotational symmetry breaking on the thermoelectric properties of homobilayer WS 2 using first-principle calculations combined with non-equilibrium Green's function approach. The in-plane rotational symmetry breaking induces structural modifications that alter the effective mass and density of states, which directly boosts the Seebeck coefficient and, consequently, the thermopower. Specifically, for both P and N-type, 38.21 • configuration exhibits the highest Seebeck coefficient, which is 1.17 and 1.13 times higher than that of the pristine homobilayer. Additionally, the lattice contributions to the heat flow is suppressed due to enhanced interfacial phonon scattering as more scattering channels emerge from superlattice formation. These synergistic effects result in a remarkable enhancement of the thermoelectric performance, with the 21.79 • twisted bilayer exhibiting an N-type ZT that is 1.25 times higher than that of the pristine homobilayer, While the 38.21 • configuration recorded a P-type ZT that is 1.21 times higher at 800 K. This represents an important milestone, given that homobilayers benefit from perfect lattice matching and structural uniformity, making them easier to fabricate than heterobilayers. These findings underscore the prospects of in-plane rotational symmetry breaking in enhancing the efficiency of thermoelectric devices.