Development of ITO-Free Alternative Transparent Conductors for High-Performance Organic and Hybrid Optoelectronics
Chung-Chih Wu1*
1Department of Electrical engineering, National Taiwan University, Taipei, Taiwan
* presenting author:Chung-Chih Wu,
The transparent conductor indium tin oxide (ITO) has been widely used in organic light-emitting devices (OLEDs) and other organic optoelectronics as the transparent electrode. ITO, however, is rather expensive and thus not cost-effective due to scarcity of the indium element on earth. ITO is also brittle and usually requires high-temperature processing, limiting its compatibility with flexible plastic substrates and thus its use for flexible devices. Accordingly, in recent years, alternative (ITO-free) transparent conductors/electrodes for replacement of ITO are being intensively pursued.
In this contribution, we would present our efforts in developing high-conductivity transparent conducting polymer poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) as ITO-free alternative transparent conductors. Excellent electrical properties (conductivity up to 1000 S/cm and sheet resistance<30 Ω/sq.) and optical properties (T>90%) have been obtained through engineering phases and morphologies of such transparent conducting polymers. Superior electrochemical activity can also be obtained such transparent conducting polymers through embedded nanostructures. By judiciously utilizing unique properties of such ITO-free alternative transparent conductors, high-performance organic and hybrid optoelectronics (such as organic light emitting devices and solar cells etc.) showing efficiencies higher than devices using conventional ITO electrodes have been demonstrated.

Keywords: transparent conductor, conducting polymer, organic optoelectronics