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Laser ablation of transparent conducting materials for organic electronics
|Large-area Organic and Printed Electronics Convention, LOPE-C 2011. Proceedings : 28.-30.6.2011, Frankfurt a.M., Germany|
Frankfurt/M.: Electronics Association, 2011
|Large-area Organic and Printed Electronics Convention (LOPE-C) <2011, Frankfurt/Main>|
| Conference Paper|
|Fraunhofer ILT ()|
One of the great advantages of polymer electronics is the possibility to produce low cost electronics by fast printing methods. Screen and inkjet printing offer minimal features sizes of 10 µm and are therefore not accordable with small structure sizes of a few microns or even sub microns as needed for highly integrated circuits. To achieve structures of this size most of the possible methods are very time consuming and thus cannot be applied in a reel-to-reel process. Laser processing provides a possible solution for a fast and high resolution patterning method for transparent conducting materials which are needed for OLEDs, organic photovoltaics, fully transparent displays and transparent circuits. The ablation of such materials as for example ITO (Indium Tin Oxide) and PEDOT/PSS (Poly (3, 4-ethylene dioxythiophene) Poly (styrenesulfonate)) is based on photochemical ablation and stress based evaporation. In this paper the ablation at different wavelengths from the deepultraviolet range with excimer lasers up to the infrared range with solid state lasers is discussed. By evaluation of the different thin films using UV/VIS/NIR spectrometry measurements the optimal wavelength for micro patterning of each material is determined. The different ablation mechanisms at the different wavelengths are examined. Special emphasis will be put on the accuracy of the edges of the ablated areas. This has been investigated by different microscopy methods such as optical microscopy, white light interferometer microscopy (WIM) and atomic force microscopy (AFM). Different patterning methods, like ablation via mask projection, scanner based ablation and ablation via microscopy optics will be compared concerning process speed and achievable highest resolution.