Ink-Jet Instability Behavior Analysis for Polymer Light Emitting Diodes Fabrication

摘要

A polymer light emitting diodes (PLED) is manufactured by thermal bubble ink-jet (TIJ) printing technique. This study is to solve the innate character of ink-jet instability causes the device defect in manufacturing process. Analysis shows that the ink-jet instability occurs at the beginning of each strip pixel because of the mechanical inertia force, the head start-driving instability, and the capillary pressure-driving force effects on drop landing on substrate. The mechanical inertia force generally causes an exponential decay of drop position deviation with the printing distance, and the head start-driving instability makes some nozzles have a critical characteristic in drop landing behavior. Besides, we found different bank pattern at start and end side to regulate the pressure difference will dramatic improve the uniformity of the polymer film in drying. The data shows that converging opening channel of bank pattern got uniform polymer film, and a closing channel of bank pattern made a local defect at both end of strip. By this analysis and improvement, the transient instability can be solved at same time not in conflict. Ink-jet line-width can be very stable and consistence, the line-width average is approximately 95.4 μm and the variation is approximately 2.5%. The printing PEDOT layer and the printing Green-PF layer above said PEDOT layer, it appeared a perfect film distribution in both.