Solution-Processed Highly Conductive Polymer and Polymer Nanocomposite Films as the Transparent Electrode of Optoelectronic Devices

J. Ouyang
National University of Singapore, SG

Keywords: nanocomposite, transparent electrode, conductivity

Summary:

Optoelectronic devices, such as liquid crystal displays (LCDs), light-emitting diodes (LEDs), solar cells, touch panel displays, lasers and detectors, have important application in many areas. Their market has been huge and has kept growing. An optoelectronic device requires at least one electrode to be transparent in order to emit or harvest light. Indium tin oxide (ITO) is currently the most popular material as the transparent electrode of optoelectronic devices. However, ITO has problems of scarce indium on earth, high mechanical brittleness, and poor adhesion to organic and polymeric materials. Therefore, there is strong demand for new transparent conductive materials to replace ITO. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is promising to be the next-generation transparent electrode material. PEDOT:PSS films can be prepared by solution processing. They have high transparency in the visible range, high mechanical flexibility, and excellent thermal stability. However, an as-prepared PEDOT:PSS film from aqueous PEDOT:PSS solution usually has a conductivity below 1 S cm-1, which is remarkably lower than ITO. Here, we will report novel and facile methods to develop PEDOT:PSS, PEDOT:PSS/carbon nanotube composites and PEDOT:PSS/graphene composites with high conductivity and transparency. The conductivity of over 3000 S/cm has been observed, which is comparable to that of ITO.