Applications of Carbon Nanotubes to Flexible Transparent Conductive Electrodes

Transparent conductive electrodes (TCEs) have attracted great interest because of their wide range of applications in solar cells, liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs), and touch screen panels (TSPs). Indium-tin-oxide (ITO) thin films as TCEs possess exceptional optoelectronic properties, but they have several disadvantages such as a brittle nature due to their low fracture strain and lack of flexibility, a high processing temperature that damages the flexible substrates, low adhesion to polymeric materials, and relative rarity on Earth, which makes their price unstable. This has motivated several research studies of late for developing alternative materials to replace ITO such as metal meshes, metal nanowires, conductive polymers, graphene, and carbon nanotubes (CNTs). Out of the abovementioned candidates, CNTs have advantages in chemical stability, thermal conductivity, mechanical strength, and flexibility. However, there are still several problems yet to be solved for achieving CNT-based flexible TCEs with excellent characteristics and high stability. In this chapter, the properties of CNTs and their applications especially for flexible TCEs are presented, including the preparation details of CNTs based on solution processes, the surface modification of flexible substrates, and the various types of hybrid TCEs based on CNTs