Abstract
Organic (Alq<sub>3</sub>) film, which was coated on a donor
plate, was transferred to an organic light emitting diode (OLED) substrate with help
of heat generated by a dithering laser beam. The laser beam was diffracted in an
acousto-optic modulator (AOM), then focused on the laser-to-heat converting layer of
the donor plate; the focused spot followed trajectories guided by rotation of a
Galvano-mirror. Three different functional waveforms, sine wave, square wave, and
saw tooth wave were applied to the AOM as modulation signal to generate the
dithering beam. The fluorescence microscope images of the donor plate showed that
the patterns of removed Alq<sub>3</sub> film were affected
considerably by the modulation waveforms and the phase difference between adjacent
dithering beams. Further, the printed images of Alq3 film on the OLED substrate were
different from the patterns of removed Alq<sub>3</sub> film. Atomic force microscope images
indicated that not only direct transfer but also deposition by sublimated vapor of
Alq<sub>3</sub> contributed to the pattern formation. Printed patterns affected considerably
the electricity-to-light conversion characteristics of OLEDs. For uniform transfer,
not only the phase relation of dithering beam lines but also adequate waveform were
important.
© 2011 Optical Society of Korea
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