Charge Transport in Thermoelectric SnSe Single Crystals

Abstract

SnSe has attracted increasing attention as a promising thermoelectric material. In this work, a horizontal vapor transfer method was developed to synthesize high-quality, fully dense, and stoichiometric SnSe single crystals, which enables an evaluation of the transport properties inherent to SnSe along the bc-plane. The electronic transport properties can be well-understood by a single parabolic band model with acoustic phonon scattering, enabling insights into the fundamental material parameters determining the electronic properties. The lattice thermal conductivity (κl) decreases from 2.0 W m–1 K–1 at 300 K to 0.55 W m–1 K–1 at 773 K. It is revealed that an increase in hole concentration, an involvement of low-lying bands for transport, and a further reduction in κl would all enable p-type SnSe to be a promising eco-friendly thermoelectric material. This work not only provides a fundamental understanding of the charge transport but also guides the further improvement of thermoelectric SnSe.