Flexible Thermoelectric Composites for Energy Harvesting

This chapter reviews recent advances in flexible thermoelectric composites for next-generation energy harvesting. Flexible thermoelectrics have emerged as a promising alternative to rigid Bi 2 Te 3 -based materials, enabling conformal power generation from low-grade heat sources such as human skin, pipelines, and ambient environments. After introducing the fundamentals of the Seebeck effect and key transport parameters (S, σ, k, ZT ), the chapter discusses the advantages and challenges of flexible composites in wearable electronics, IoT devices, and curved surfaces. Conductive polymers such as PEDOT:PSS, PANI, and PPy offer low thermal conductivity, mechanical flexibility, and solution processability, while inorganic nanomaterials—including Bi 2 Te 3 /Sb 2 Te 3 nanostructures, graphene, and carbon nanotubes—provide high electrical conductivity and enhanced thermoelectric performance. Hybrid polymer–inorganic nanocomposites are highlighted as a balanced strategy, combining improved charge transport, interfacial phonon scattering, and tunable thermoelectric properties. Strategies to enhance ZT, including filler dispersion, percolation network formation, interfacial engineering, nanostructuring, and energy filtering, are summarized. Emerging materials such as MXenes, MOFs, and 2D semiconductors, along with self-healing and stretchable thermoelectric systems, point toward durable, high-performance flexible devices. These developments position flexible thermoelectric composites as key materials for sustainable, self-powered electronics.