8 - Conjugated polymer-based electrodes for flexible all-solid-state supercapacitors

Abstract

Intrinsically conducting π-conjugated polymers (CPs) exhibit several unique characteristics, including reduced ionization potential, optical transmission at low energy, enhanced electron affinities, adjustable conductivity, selective doping–de-doping attributes, facile processability, and eco-friendliness. Since their discovery, CPs have been explored exclusively for a wide range of applications such as organic light-emitting diodes, thin-film transistors, organic solar cells, sensors, electrochromic displays, batteries, and supercapacitors. All-solid-state flexible supercapacitors (FSCs) are characterized by considerable flexibility, augmented charge storage, and tuning resistance of electroactive materials, resulting in high charge storage abilities. These have emerged with the potency to pave the path for major advances in cutting-edge mobile, lightweight, and flexible electronics, viz. photovoltaic cells, roll-up displays, and wearable devices. CPs and their nanocomposites are amongst the most creditable electrode materials underpinning flexible supercapacitors attributed to the elevated redox facilitated specific capacitance and intrinsic elastic polymeric nature. This chapter provides a detailed review of the recent investigations conducted and the progress has been through in the further development of CP-based nanocomposites as flexible electrodes for SCs. The latest progress in designing flexible supercapacitors based on binary and ternary nanohybrid composites of CPs with various carbonaceous materials (such as carbon nanotubes, carbon nano-onions, graphene, carbon nanoparticles, etc.), metal-based compounds, MXenes, and metal–organic frameworks are discussed. Furthermore, this chapter presents a brief discussion about improved device fabrication techniques, designing concepts implementing appropriate substrates, and electrolytes included, as well. The chapter ends on a final note with a brief discussion on the existing challenges and future perspectives for CP-based FSCs.