Dense twin and domain boundaries lead to high thermoelectric performance in Sn-doped Cu3SbS4

Abstract

Exploring high-performance medium-temperature thermoelectric (TE) materials with nontoxicity and low price is of great significance for waste heat recovery. In spite of low price and nontoxicity, the poor intrinsic electrical properties of Cu3SbS4 restrict its potential commercial applications. Herein, intermediate-phase-free Cu3SbS4-based bulks were fabricated by incorporating a sulfurization process between melting and sintering, and the as-formed dense twin and domain boundaries in a Sn-doped Cu3SbS4 system can significantly enhance the electrical conductivity and retain a higher level of the Seebeck coefficient based on the energy filtering effect and band flattening and convergence. The high power factor of ∼13.6 μW cm−1 K−2 and relatively low thermal conductivity are achieved for a 1.5%Sn-doped Cu3SbS4 sample, resulting in a record zT of ∼0.76 at 623 K in Cu3SbS4-based systems. This work develops an effective pathway to synthesize intermediate-phase-free Cu3SbS4-based TE materials and provides an effective strategy for enhancing TE performance in diamond-like semiconductors by interface engineering.