Comprehensive Insights into Synthesis, Structural Features, and Thermoelectric Properties of High-Performance Inorganic Chalcogenide Nanomaterials for Conversion of Waste Heat to Electricity

Thermoelectrics are energy harvesters that can directly convert waste heat into electrical energy and vice versa. Currently, thermoelectric (TE) devices display lower efficiency as the materials used for construction possess a very low figure of merit (ZT). Therefore, understanding the structural features of materials, finding new materials, and analyzing their chemistry and physics play a vital role in enhancing their energy conversion efficiency. Among the different classes of TE materials, some inorganic chalcogenides are perfect candidates for power generation as they possess excellent TE properties. The objective of this review is to provide insights into structural features and innovative methods to obtain enhanced thermoelectric properties of selected inorganic chalcogenides. The review covers recent advances in preparation methods, structural features, and thermoelectric properties of selected metal selenides (Bi2Se3, Ag2Se, SnSe, etc.) and metal tellurides (Bi2Te3, SnTe, PbTe, etc.). The review also discusses the critical parameters for designing and optimizing the TE materials to obtain the required electrical conductivity (sigma), Seebeck coefficient (S), and thermal conductivity (k). In addition, promising mechanistic approaches to be adopted for enhancing the efficiency of TE materials such as doping, alloying, and nanostructuring are discussed in detail. Finally, a summary that describes advancements in the materials design is provided with a prospect for future applications from these materials in the development of energy harvesting technology.