Ag2Se-based thermoelectric materials and devices: Progress, challenges, and perspectives

Abstract

Ag2Se has emerged as one of the most promising n-type thermoelectric candidates for near-room-temperature energy harvesting and solid-state cooling, owing to its exceptionally high carrier mobility, intrinsically low lattice thermal conductivity, scalable synthesis routes, and relatively low material cost. These advantages make Ag2Se particularly attractive for sustainable power supply in wearable electronics and Internet-of-Things (IoT) applications. In recent years, intensive efforts in materials engineering and device design have driven rapid progress in Ag2Se-based thermoelectrics, which calls for a timely and comprehensive review. This article systematically summarizes the latest advances in the synthesis, modification, and application of Ag2Se thermoelectric materials in bulk, thin-film, and fiber forms. Recent breakthroughs in device integration are also critically examined, highlighting high-efficiency flexible thermoelectric generators, active cooling modules, and mechanically robust self-powered sensors enabled by this emerging material system. By linking fundamental transport mechanisms with practical device architectures, this review identifies key strategies to address challenges in stability and scalability, thereby facilitating the commercialization of flexible Ag2Se-based thermoelectric technologies.