Recent advances, challenges, and perspective of copper-based liquid-like thermoelectric chalcogenides: A review

As a group of emerging liquid-like thermoelectric materials for waste heat recovery into useful energy, di-chalcogenides Cu-2(S, Se, Te) have been considered as superionic thermoelectric materials. Due to their highly disordered degree of Cu-ion in the crystal lattice, Cu-2(S, Se, Te) compounds can exhibit ultralow thermal conductivity, and in the meantime, their rigid sublattice can decently maintain the electrical performance, making them distinct from other state-of-the-art thermoelectric materials. This review summarizes the well-designed strategies to realize the impressive performance in thermoelectric materials and their modules by linking the adopted approaches such as defect engineering, interfaces, nano-porous inclusions, thin films, dislocations, nano-inclusions, and polycrystalline bulks etc., with the moderate design of the device. Some recent reports are selected to outline the fundamentals, underlined challenges, outlooks, and future development of Cu-2(S, Se, Te) liquid-like thermoelectric materials. We expect that this review covers the needs of future researchers in choosing some potential materials to explore thermoelectricity and other efficient energy conversion technologies.