Novel synthesis recipes boosting thermoelectric study of A2Q (A = Cu, Ag; Q = S, Se, Te)

Discovering new materials and developing novel synthesis techniques are like two wheels of a cart in materials-based science and technology. As is often the case, innovative synthesis recipe can rejuvenate the research landscape of a material that is otherwise thought to be matured. A good example of such is the narrow band gap semiconductor/semimetal family of A(2)Q (A = Cu, Ag; Q = S, Se, Te). Here we briefly review the recent development of synthesis recipes and the impact on the thermoelectric study of A(2)Q. While the mixed ionic electronic conduction in A(2)Q promises advantages in thermoelectricity, it poses challenges in material synthesis and applications. The concepts, approaches, and strategies embodied in these novel synthesis recipes of A(2)Q can be extended to other materials in diverse regimes of fundamental research and technical applications beyond thermoelectrics.