Ternary CuSbSe2 chalcostibite: facile synthesis, electronic-structure and thermoelectric performance enhancement

Abstract

A single phase CuSbSe₂ polycrystalline chalcostibite compound has been facilely synthesized through mechanical alloying for the first time, and the phase evolution has been revealed in detail. The large Seebeck coefficient and poor electrical conductivity of this compound are ascribed to the existing Cu–Se ionic bonding and heavy band at the VBM. The active lone-pair s² electrons in Sb³⁺ ions are likely to be responsible for the experimentally observed low thermal conductivity in the CuSbSe₂ compound. By introducing narrow band-gap Cu₃SbSe₄ into the CuSbSe₂ matrix, the carrier concentration and mobility can be tuned effectively; thus the power factor has been improved remarkably. As a consequence, the figure of merit (ZT) is increased by a factor of 1.6 at 623 K, from 0.25 (matrix) to 0.41.