A review on high-performance flexible thermoelectrics: material, device, and applications

Flexible thermoelectric (TE) materials and their devices have gained increasing attention due to the flexibility and lightness of flexible TE technology for low-temperature waste heat collection. In recent decades, various efforts have been devoted to the impressive efficiency of flexible thermoelectric technology including the synthesis, designing, and integration of flexible thermoelectric generators (TEGs). In this regard, the urgent need for eco-friendly, stable, and durable power sources motivates the booming market for integrated electronics. This review comprehensively summarizes the state-of-the-art development of flexible thermoelectric materials, device types, fabrication techniques, and the fundamentals behind their applications. In addition, the employed methods for moderate physical properties including theoretical analysis, experimental prospects, and importantly the challenges of flexible thermoelectrics are introduced. Moreover, we summarized the applications of flexible thermoelectrics in textiles, wearable electronics, waste heat utilization, and their applications in sensors, the Internet of Things, health monitoring, etc. We believe that this review addresses the current research challenges and their future directions to the researchers for choosing potential materials to explore flexible thermoelectric technology.