Micro patterning of organic solvents on OLED device using EHD inkjet technology

Although there are many modes of the ejection mechanism from the EHD nozzle [2], a cone-jet mode, a pulse-jet mode and a micro-dripping mode have been analyzed by capturing the jetting phenomena using organic solvents as working fluids in this study to find out the optimum liquid for each mode at the required condition. The detailed jetting mechanisms and modes have been investigated to design the EHD jetting system optimally and to examine forces on the jetting mechanism for droplet-on-demand operation according to important physical parameters such as an onset voltage, liquid conductivity, surface tension, viscosity, etc. The effect of the factors has been analyzed by the experiments initially to confirm the dominant factors for the determination of the width of the patterned line, which should be less than 100μm. Then, the modeling equation has been derived to calculate the jetting mechanism numerically using those important factors and to compare with the experimental results of the micro-sized patterning. The EML (EMission Layer) of the OLED (Organic Light Emitting Diodes) device has been calculated numerically by the confirmed equation and fabricated experimentally by the developed micro patterning technology using the EHD inkjet system in this study.