Chalcostibite single-crystal CuSbS2 as high-performance thermoelectric material

Abstract

Chalcostibite CuSbS2 has attracted attention as an environmentally friendly material in thermoelectric (TE) field. Our investigations into the TE properties of high-quality p-type CuSbS2 single crystals revealed that they exhibit a uniquely low thermal conductivity caused by the active lone-pair electrons in Sb3+ ions. The electrical conductivity was improved by the high density of shallow acceptor Cu vacancies and the absence of potential barriers to carrier transport. Consequently, the figure of merit for the Cu-poor CuSbS2 single crystal reached 0.5 at 700 K, which is 25 times higher than that of the reported polycrystalline sample.