Multifunctional Copper‐Based Quaternary Chalcogenide Semiconductors Toward State‐of‐the‐Art Energy Applications

Abstract Cu‐based quaternary chalcogenide semiconductors have been attractive materials in many aspects since the last decade. Most of the scientific literature about quaternary chalcogenides is dedicated to photovoltaic (PV) research with no astonishment as the material initially emerged as a cost‐effective replacement of expensive Si for PV applications. These materials possess all the important properties such as, abundant and non‐toxic constituent elements, efficient charge transport, optimum band gap, and high absorption coefficient for being an efficient PV material in either thin film or nanoparticle form. However, in the recent few years, a new range of quaternary materials Cu₂M_IM_IIX₄ (where, M_I=Zn, Ni, Co, Fe, Mn, Cd and Hg; M_II=Si, Sn and Ge and X=S and/or Se) have evolved and found applications in thermoelectrics, photocatalysis and photoelectrocatalysis, sensors and batteries etc. The combination of properties exhibited by these quaternary chalcogenides such as optical and electric, optical and magnetic, electric and thermal makes them potential materials, which could be utilized in multiple applications. Although the PV properties of these quaternary chalcogenides has been discussed earlier in many reports, the other versatile applications of the material have not been reviewed yet. The present article sheds light on the multifunctional aspects of various new Cu‐based quaternary chalcogenides, their synthesis, effect of doping on their properties, and then elaborating the discussion on their chemical and physical properties that are helpful in different applications along with photovoltaics. Here, we discuss synthetic methods bestowing enhanced features and also summarize their achieved efficiency in recent years.