Thermoelectric Copper and Silver Chalcogenides

The importance of thermoelectric (TE) energy generation as a sustainable energy conversion method continues to increase. Recently, the focus has begun to shift from tellurides to more abundant and environmentally benign sulfides and selenides. For these materials, other methods of achieving low thermal conductivity must be used because they are composed of lighter elements. An advantageous property in this regard is anharmonicity, as demonstrated for SnSe and the tetrahedrites Cu 12-x M x Sb 4 S 13 , with M = Mn, Fe, Co, Ni, Zn and Hg. A second is extreme disorder, all the way up to a "liquid-like" sublattice as realized in various copper chalcogenides, the focus of this chapter, including β-Cu 2 Se. The chapter also discusses the connection between binary copper and silver chalcogenides as well as ternary and higher copper and silver chalcogenides.