Passivation of organic light emitting diode anode grid lines by pulsed Joule heating

• Published in: Applied physics letters 2015-09, Vol.107 (10)
• Main Authors: Janka, M., Gierth, R., Rubingh, J.-E., Abendroth, M., Eggert, M., Moet, D. J. D., Lupo, D.
• Format: Article
• Language: English
• Subjects: Accuracy; Alignment; Anodes; Applied physics; Conduction heating; Conductive heat transfer; Current distribution; Current pulses; Magnetic fields; Ohmic dissipation; Organic light emitting diodes; Passivity; Polymers; Resistance heating; Self alignment
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4930883

We report the self-aligned passivation of a current distribution grid for an organic light emitting diode (OLED) anode using a pulsed Joule heating method to align the passivation layer accurately on the metal grid. This method involves passing an electric current through the grid to cure a polymer dielectric. Uncured polymer is then rinsed away, leaving a patterned dielectric layer that conforms to the shape of the grid lines. To enhance the accuracy of the alignment, heat conduction into the substrate and the transparent electrode is limited by using short current pulses instead of a constant current. Excellent alignment accuracy of the dielectric layer on printed metal grid lines has been achieved, with a typical 4-μm dielectric overhang. In addition to good accuracy, pulsed Joule heating significantly cuts down process time and energy consumption compared to heating with a constant current. The feasibility of using a printed current distribution grid and Joule heating was demonstrated in an OLED device.