A concise review on the progression of copper sulfide as a potential thermoelectric material: Synthesis and thermoelectric properties

Abstract

Copper sulfides are an interesting group of materials as they are found in various stoichiometries. Covellite (CuS), digenite (Cu1.8S), and chalcocite (Cu2S) are the three major phases of copper sulfides. Synthesis of copper sulfide nanostructures via diverse techniques such as solvothermal, pyrolytic, and high-temperature precursor injection has been done for various applications, including electrochemical capacitance, lithium storage and transdermal drug delivery. Additionally, they have been found to show promising behaviour as thermoelectric materials. Thermoelectric energy generation is a fascinating method for energy generation. It is a renewable energy source which utilizes waste heat and converts it into electrical energy, hence is of high value since renewable sources of energy are the need of the hour. Thermoelectric materials are broadly classified into three types: organic, inorganic, and hybrid. Bismuth telluride (Bi2Te3), lead telluride (PbTe), silicon-germanium (SiGe) and their alloys are some of the most widely used thermoelectric materials. However, most of these materials are toxic, expensive and its challenging to improve their figure of merit (zT). Copper sulfides have emerged as cost-effective, less toxic alternatives to traditional thermoelectric materials, and different approaches such as doping and phase regulation of copper sulfides have been found to further enhance their thermoelectric properties.