Copper chalcogenide thermoelectric materials

Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency, tunable transport properties, high elemental abundance and low toxicity. In this review, we summarize the recent research progress on this large family compounds covering diamond-like chalcogenides and liquid-like Cu2X (X=S, Se, Te) binary compounds as well as their multinary derivatives. These materials have the general features of two sublattices to decouple electron and phonon transport properties. On the one hand, the complex crystal structure and the disordered or even liquid-like sublattice bring about an intrinsically low lattice thermal conductivity. On the other hand, the rigid sublattice constitutes the charge-transport network, maintaining a decent electrical performance. For specific material systems, we demonstrate their unique structural features and outline the structure-performance correlation. Various design strategies including doping, alloying, band engineering and nanostructure architecture, covering nearly all the material scale, are also presented. Finally, the potential of the application of Cu-based chalcogenides as high-performance thermoelectric materials is briefly discussed from material design to device development.