Moiré-pattern-assisted thermoelectric enhancement in tungsten diselenide bilayer

Abstract

Two-dimensional transition metal dichalcogenides (TMDs) have emerged as a promising material for thermoelectric applications due to their tunable electron and phonon transport properties. In this work, we investigate the thermoelectric performance of a twisted tungsten diselenide (WSe₂) bilayer and compare it with the untwisted configuration using first-principles calculations combined with Boltzmann transport theory. We find that twisting the WSe₂ bilayer by 12.53° can significantly reduce the lattice thermal conductivity by a quarter from 26.59 W m⁻¹ K⁻¹ at T = 300 K for the untwisted bilayer. This is primarily due to enhanced anharmonicity and phonon scattering arising from Moiré-induced structural modifications. Although the thermoelectric power factor reduces due to symmetry breaking which enhances electrons scattering rate, a signification reduction in thermal conductivity (∼77%) leads to an improved thermoelectric figure of merit of 0.46 at 300 K and 1.40 at 700 K for the twisted WSe₂ bilayer. Our findings highlight the role of twist engineering as an effective strategy to optimize electron and phonon transport in layered TMDs, for the design of high-performance thermoelectric materials.