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Proceedings Paper

A laser induced local transfer for patterning of RGB-OLED-displays
Author(s): Michael Kroeger; Marc Hueske; Thomas Dobbertin; Jens Meyer; Henning Krautwald; Thomas Riedl; Hans-Hermann Johannes; Wolfgang Kowalsky
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Paper Abstract

RGB-OLED-displays can be realized by at least three different approaches: Color from white, color from blue or patterning of red, green and blue OLEDs, which is favorable for reasons of higher efficiency and lower costs. Common patterning techniques like photolithography cannot be applied due to the degradation of the OLEDs after the exposure to solvents. Shadow masking which is currently widely applied is not applicable for bigger substrate sizes of future mass production tools. Therefore a novel approach for patterning of organic semiconductors will be demonstrated. The laser induced local transfer (LILT) of organic small molecule materials allows for mass production of high resolution RGB-OLED-displays. An infrared absorbing target is coated with the desired emitting material, which is placed in a short distance in front of an OLED substrate. A scanner deflects and focuses an infrared laser beam onto the target. By adjusting scanning speed and laser power accurately the target locally heats up to a temperature where the organic material sublimes and will be deposited on the opposite OLED substrate. By repeating this for red, green and blue emitting materials a RGB-OLED-display can be realized. For process evaluation and development a LILT-module has been built, incorporating two custom vacuum chambers, several lift and transfer stages, a high-speed high-precision scanner and an infrared continuous-wave laser (cw). This module is designed to be part of a future inline deposition system for full-color OLED displays. In the first experiments it could be observed, that the pattern resolution is strongly dependent on the scanning speed, exhibiting minimum feature sizes of 40μm. It can be deducted that this is due to the laser's beam profile (TEM00), which allows for the smallest focus possible, but may not allow for rugged process conditions suitable for production. Rectangular steep-edged beam profiles may overcome this problem.

Paper Details

Date Published: 7 July 2005
PDF: 8 pages
Proc. SPIE 5840, Photonic Materials, Devices, and Applications, (7 July 2005); doi: 10.1117/12.608702
Show Author Affiliations
Michael Kroeger, Technische Univ. Braunschweig (Germany)
Marc Hueske, LPKF Laser & Electronics AG (Germany)
Thomas Dobbertin, Technische Univ. Braunschweig (Germany)
Jens Meyer, Technische Univ. Braunschweig (Germany)
Henning Krautwald, Technische Univ. Braunschweig (Germany)
Thomas Riedl, Technische Univ. Braunschweig (Germany)
Hans-Hermann Johannes, Technische Univ. Braunschweig (Germany)
Wolfgang Kowalsky, Technische Univ. Braunschweig (Germany)

Published in SPIE Proceedings Vol. 5840:
Photonic Materials, Devices, and Applications
Goncal Badenes; Derek Abbott; Ali Serpenguzel, Editor(s)

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