Polymer based thermoelectric nanocomposite materials and devices: Fabrication and characteristics

Organic thermoelectric (TE) materials capitalize on advantages such as low thermal conductivity, low-cost, eco-friendly, versatile processability, light-weight, mechanical flexibility, roll-to-roll production, which are advantageous for the development of portable and wearable self-powered electronics. On the negative side, the figure-of-merit of polymer TE materials is low, mainly owing to typical low electrical conductivity. Various efforts have been made to enhance the TE performance of organic TE materials, i.e. chemical or electrochemical doping, modification of molecular structure, and fabrication of polymer-based composites or blends, which is the simplest and most cost-effective method for modifying polymer properties. Solution-processed polymer/inorganic or organic hybrids pave the way for formulation of functional TE inks/paste which can be used to fabricate large scale cost-effective manufacturing of TE generators. In this review, we briefly summarize the TE properties of conjugated polymers, and focus on recent developments in polymer/carbon nanofillers (e.g. CNT, graphene, GO) composites and polymer/inorganic TE nanoparticles composites along with preparation methods and thermoelectric performance. Finally, we cover recent advances in the development of functional TE inks, processing techniques, and their usage in device fabrication using various printing techniques and review device output characteristics.