Silver Copper Chalcogenide Thermoelectrics: Advance, Controversy, and Perspective

Thermoelectric technology, which enables a direct and pollution‐free conversion of heat into electricity, provides a promising path to address the current global energy crisis. Among the broad range of thermoelectric materials, silver copper chalcogenides (AgCuQ, Q = S, Se, Te) have garnered significant attention in thermoelectric community in light of inherently ultralow lattice thermal conductivity, controllable electronic transport properties, excellent thermoelectric performance across various temperature ranges, and a degree of ductility. This review epitomizes the recent progress in AgCuQ‐based thermoelectric materials, from the optimization of thermoelectric performance to the rational design of devices, encompassing the fundamental understanding of crystal structures, electronic band structures, mechanical properties, and quasi‐liquid behaviors. The correlation between chemical composition, mechanical properties, and thermoelectric performance in this material system is also highlighted. Finally, several key issues and prospects are proposed for further optimizing AgCuQ‐based thermoelectric materials. Thermoelectric technology enables direct, pollution‐free heat‐to‐electricity conversion. Silver‐copper‐based semiconductors (AgCuQ, Q = S, Se, Te) demonstrate compelling attributes, such as ultralow thermal conductivity, tunable electronic properties, and ductility. This review summarizes their fundamentalfeatures and recent achievements, including crystal structures, electronic bands, mechanical features, and strategies for performance enhancement, as well as addressing challenges and prospects.