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