Conductive Polymer Nanocomposites for Organic Light-Emitting Diodes (OLEDs)

Abstract

A one-step synthesis technique has been used to fabricate sensors by growing polyaniline nanofibers and polyaniline/metal nanocomposites in the active area of an interdigitated electrode array. Polyaniline nanofiber sensors can be fabricated by irradiating an aqueous precursor solution containing aniline, HCl, a metal salt, and ammonium persulfate (APS) with a high-pressure Hg lamp. The sensors are ready for operation after polymerization is complete, and no additional processing steps are necessary. These sensors showed faster and more intense response to various organic vapors than conventional bulk polyaniline sensors due to their larger surface area. A chemisorption model and a diffusion model were used to fit the sensor response of nanostructured polyaniline sensors. Both models can mathematically fit the sensor response as a function of time. Fitting errors from the two models were in a reasonable range, both allowing reasonable mathematical forms for the time-dependent and concentration behavior. An oligomer-assisted polymerization method was carried out to synthesize polythiophene nanofibers. In this approach, a solution of thiophene, FeCl₃, and terthiophene was dissolved in acetonitrile. Compared to conventional chemical polymerization, a polythiophene oligomer, terthiophene or bithiophene, was added to assist the formation of nanofibers. In this review, we focus on the emerging alternative TCE materials for OLED applications, including carbon nanotubes (CNTs), metallic nanowires, conductive polymers, and graphene. These materials are selected, because they have been applied as transparent electrodes for OLED devices and achieved reasonably good performance or even higher device performance than that of indium tin oxide (ITO) glass.