Crystal Structure Classification of Copper-Based Sulfides as a Tool for the Design of Inorganic Functional Materials.

Research focusing on the interplay between structural features and transport properties of inorganic materials is of paramount importance for the identification, comprehension, and optimisation of functional materials. In this respect, Earth-abundant copper sulfides have been receiving considerable attention from scientists as the urgency remains to discover and improve the efficiency of sustainable materials for energy applications. This proposed classification of copper sulfides, associated with p- and/or d-block elements, is based on their crystallographic features and an analysis of their transport properties. It provides guidelines to help estimate some properties of new materials (type of main charge carriers, thermal conductivity, transport mechanisms, etc.) from consideration of only their chemical composition and crystal structure. The classification relies primarily on recent studies in the fields of thermoelectricity and photovoltaics as well as on crystal-structure investigations.