Investigation of the Influence of Laser Radiation on Material Properties of Transparent Conductive Layers

Organic electronic devices like organic thin film transistors with micron or even sub-micron sized features can be fabricated at high throughput by fast printing methods combined with high resolution laser patterning. In addition, such an approach is of interest for applications with lower requirements in resolution, such as OLEDs or OPV. Due to its high flexibility and adaptability to almost any material or material system, laser processing is a perfect tool for the production of organic electronics. In all the applications above, it is of severe importance not to cause damage to adjacent material or layers by laser radiation. For transparent conductive layers laser-induced damage can lead to changes in conductivity, transparency or material composition (e.g. oxidation). Therefore, a comprehensive study was performed to investigate the influence of laser radiation below ablation threshold on material properties of transparent conducting layers (e.g. ITO, PEDOT/PSS). Samples were irradiated by a large range of wavelengths, reaching from the deep UV (193 nm) up to near IR (1064 nm). To identify changes in material properties the samples were characterized by microscopic methods like high resolution laser scanning microscopy and conductive atomic force microscopy. Also spectroscopic methods like UV/VIS/NIR absorption spectroscopy as well as X-ray photoelectron spectroscopy were used in order to determine changes in conductivity and material composition.