Decoupling of thermal and electrical conductivities by adjusting the anisotropic nature in tungsten diselenide causing significant enhancement in thermoelectric performance

Abstract

A polycrystalline WSe2 nanocompound was produced via a brief thermal reaction between the atomic elements. It should grow along the in-plane direction with covalent bonds rather than along the through-plane direction with van der Waals forces, leading to both crystallographic and morphological anisotropies. Not only the anisotropies should structurally induce strong phonon scattering but they alleviate possible electron scattering at the van der Waals forces; thus, we greatly reduced thermal conductivity while minimizing electrical conductivity loss. The decoupled conductivities resulted in enhancement in figure of merit, by approximately 70% at 350°C, thus affording a promising material for mid-temperature thermoelectric operations. © 2017 The Korean Society of Industrial and Engineering Chemistry.