Solution and Evaporation Hybrid Approach to Enhance the Stability and Pattern Resolution Characteristics of Organic Light-Emitting Diodes.

ABSTRACT

The solution process and vacuum evaporation, both fabrication methods for conventional organic light-emitting diodes (OLEDs), are intrinsically restricted with regard to their ability to enhance pattern resolutions and film stability outcomes. Here, we introduce a novel approach of the solution process followed by intense pulsed light (IPL) evaporation for producing high-resolution line patterns of OLEDs. Through control of the wettability between the banks and microchannels via a mask-free selective surface treatment, we successfully deposited phosphorescent green and red inks only into the microchannels. Then, high-resolution patterns of an emitting layer (EML) layer were uniformly evaporated onto the device substrate using IPL evaporation. Ultimately, we fabricated green and red phosphorescent OLED devices with a high pixel density of a line-patterned EML with a width of 6 µm and a pitch of 13.6 µm. In addition, we demonstrated that the IPL-evaporated films have many advantages compared to those fabricated by the conventional solution process. We also showed that the IPL evaporation process can be less sensitive to problems related to the aggregation of organic molecules during a drying or annealing process. Hence, the device performance and lifetime of the IPL-evaporated OLEDs were enhanced compared to those of the spin-coated OLEDs.