Environmentally friendly thermoelectric sulphide Cu2ZnSnS4 single crystals achieving a 1.6 dimensionless figure of merit ZT

Thermoelectrics (TEs) are an important class of technology that harvest electric power directly from heat sources. When designing both high performance and environmentally friendly TE materials, the pseudo-cubic structure has great theoretical potential to maximize the dimensionless figure of merit ZT. The TE multinary single crystal with a pseudo-cubic structure paves a new path toward manipulating valley degeneracy and anisotropy with low thermal conductivity caused by short-range lattice distortion. Here, we report a record high ZT = 1.6 around 800 K realized in a totally environmentally benign p-type Na-doped Cu2ZnSnS4 (CZTS) single crystal. The exceptional performance comes from a high power factor while maintaining intrinsically low thermal conductivity. The combination of the pseudo-cubic structure and intrinsic properties of the CZTS single crystal takes advantage of simple material tuning without complex techniques.

Automated summary

Thermoelectrics (TEs) are an important class of technology that can directly harvest electric power from heat sources. The use of a pseudo-cubic structure in TE materials can maximize the dimensionless figure of merit ZT, leading to high performance and environmentally friendly materials. A record high ZT of 1.6 around 800 K was achieved in a environmentally benign p-type Na-doped Cu2ZnSnS4 (CZTS) single crystal, demonstrating exceptional performance due to a high power factor and low thermal conductivity.