Cu3SnS4 chalcogenide as a low-cost, earth abundant thermoelectric material has recently attracted much attention. However, its Seebeck coefficient is rather low due to its metallic-like behavior; therefore, substantial work is required to enhance its thermoelectric (TE) properties. In this work, an alternative method is proposed, that is, a regulation of the crystal structure through alloying with Cu3SbSe3. This regulation is realized by the incorporation of Sb and Se in the Cu3SnS4 host frame with an addition of Cu3SbSe3, thus altering the bond lengths (CuS and SnS) and bond angles (SCuS and SSnS), and leading to widening of the bandgap and the convergence of top valence bands. At the same time, the lattice thermal conductivity reduces by ≈50% at high temperatures, mainly triggered by the crystal structure distortion and introduced point defects. The approach of crystal structure regulation may help design the properties of other ternary CuSn(Sb)S(Se) compounds for TE applications.
- band gap
- crystal structures
- CuSnS-based chalcogenides
- thermoelectric performance
- ultralow lattice thermal conductivity