Merck and University of Cologne: Polymer OLED using Direct Lithography

Prof. Meerholz from the U. of Cologne will present the first high-resolution, full-color OLED display based on a direct photolithographic process. The direct photolithography technique avoids most pitfalls with ink-jet printing. Existing LCD production facilities can be easily adapted. Today, three main OLED challenges remain for pixelating the emissive layer:

1. Large substrate compatibility.

2. Fine pixel structure definition.

3. Production cost reduction.

The direct photoligraphic technology does not require an entirely new process technology but requires only a chemical modification or the organic material, a material developed in collaboration with Merck OLED Materials GmbH, formerly Covion.

Oxetane side groups are added to the emissive polymers that produces photo-resist properties. A thin film of these photo-resist emissive polymers allow patterning with exposure to UV light. The first working prototype required only two months of development work according to Prof. Meerholz.

Each polymer is deposited onto a transparent substrate using spin coating. UV is irradiated onto the polymer film through a shadow mask. The polymer is cross linked and forms an insoluble material and the non-cross-linked material is washed away. Direct lithography does not have problems with variations in film thickness. A pixel density of much more than 1000 ppi was demonstrated on standard commercial and untreated glass.

Source: Social Business Club

Leave a Reply