Recent Advances in the Study of Bulk Crystals: Copper Chalcogenides

Solid crystalline materials play a crucial role in a range of technological applications, from photovoltaics to thermoelectrics. Increasing the performance of these materials is important in terms of application efficiency. This review provides an overview of recent developments in the field, with a focus on photovoltaic materials, defect chemistry, and thermoelectric properties. Copper sulfide and selenides have advantages such as environmental friendliness, low cost and improved thermoelectric efficiency that set them apart from the competition. Special emphasis is placed on copper sulfides (Cu₂S) and selenides (Cu₂Se) due to their unique structural and electronic properties, making them promising candidates for sustainable energy applications. The manifestation of these copper chalcogens occurs within a variety of crystal structures, contingent on the liquid-like motion of the Cu⁺ ion within the crystal. In this review, the defective, deficiency and regular structures identified in recent years were also discussed.