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2010
Presentation
Titel
Substrate patterning for organic electronic devices at Fraunhofer IPMS
Titel Supplements
Presentation held at Plastic Electronics, PE 2010, October 19-21, 2010, Dresden
Abstract
Substrates for organic light-emitting diodes currently are patterned by means of photolithography. In order to achieve a large market penetration in a segment like lighting, the cost issue of the complete fabrication chain is the major key for commercialisation. In the field of OLED signage and lighting alternative patterning technologies have the potential for considerable cost saving compared to standard photolithography. This is realized with much less requirements for the patterning resolution of the OLED substrate layers. Fraunhofer IPMS uses a screen printing process for OLED substrate patterning. Base is an ITO coated glass substrate (370 x 470 mm2). The ITO is patterned by printing an ITO etch paste which is activated under nitrogen atmosphere at 150 °C. After cleaning (removing the residual etch paste) only the patterned ITO layer remains on the glass. In a second step contact lines and a metal grid are printed upon the anode to compensate the insufficient sheet resistance of the ITO layer. Finally a passivation layer for isolating the metallisation grid is added to prevent short-circuits to the cathode or organic thin film layers. With this method, the manufactured OLEDs on screen printed substrates reach performance parameters comparable to substrates patterned by means of photolithography. As an alternative to printing an ITO etch paste Fraunhofer IPMS recently investigated patterning the ITO layer by means of laser ablation. This allows further enhancement of the patterning process, additionally simplifies the cleaning process after ITO patterning, and minimizes the number of ITO defects.