Moiré-Pattern-Assisted Thermoelectric Enhancement in Tungsten Diselenide Bilayer

Abstract

Two-dimensional transition metal dichalcogenides (TMDs) have emerged as promising material for thermoelectric applications due to their tunable electron and phonon transport properties. In this work, we investigate the thermoelectric performance of 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 1/4𝑡ℎ from 26.59 𝑊𝑚−1𝐾−1 at T = 300 K for 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, yet 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 designing of high-performance thermoelectric materials.