Advances in Ag₂S-based thermoelectrics for wearable electronics: progress and perspective

Traditional inorganic thermoelectric materials exhibit excellent thermoelectric performance but poor flexibility. As a new type of flexible inorganic thermoelectric material, Ag₂S owns a ductile nature and shows high flexibility and promising thermoelectric potential. Considering the rapid development of thermoelectrics, it is critical and timely to summarize the progress, challenges, and outlooks of Ag₂S. Here, we comprehensively review the crystal structure, electronic structure, thermal transport mechanism, and mechanical properties of Ag₂S. After that, we summarize the advanced strategies for improving the thermoelectric properties of Ag₂S-based materials and their assembly for high-performance flexible thermoelectric devices. The fundamentals of monolayer Ag₂S are also highlighted for potential thermoelectric applications. Finally, we point out the controversies and directions of Ag₂S-based thermoelectrics for applications in both flexible power generation and refrigeration. This review will guide researchers to pursue new directions in the field of Ag₂S.