Study Of Patterned Organic Light-emitting Diodes Fabricated By Inkjet Printing

Inkjet printing is a novel method to fabricate printed electronic devices that enables rapid, large area and efficient film deposition. It is a solution-based process, with efficient materials utilization and roll-to-roll integration. This thesis focuses on turning the organic materials into inkjet printable(on Dimatix DMP-3000 inkjet printer) inks through selection of solvents and doping. Through tuning the film forming properties, high resolution patterns can be achieved, which was then used for the fabrication of organic light emitting devices. Through the study of ink and printing properties, such as voltage setting, drop spacing, print-head temperature, substrate temperature and pre-/post-printing treatments, different film morphology can be obtained. Through the optimization of the two-component solvent system and tuning of properties such as viscosity, surface tension, concentration, different film morphology was obtained. The different wetting properties were studied to investigate their influence on film deposition in order to achieve high resolution patterning. Lastly, molecules and polymers were printed using the optimized inkjet printing processes for OLED device fabrication, throughout which detailed problems in inkjet printing were studied.