Organic light emitting device non-emissive area formation and inhibition

Abstract

In this PhD project, the study of organic light emitting device degradation process has been focused on the formation of non-emissive spots on the device active area. Cathode deterioration and polymer degradation under electrical stress have been extensively studied which contribute to the understanding of non-emissive area formation mechanism based on the device point of view. The a??dark non-emissive areaa?? has been identified as current density reduced region. My studies show that due to ITO polymer interface rough and polymer material imperfection, the local shorting point causes the formation of the dark shadow center. The heating induced polymer degradation is the main reason to cause the dark shadow area growth. A novel OLED structure design and suitable process technology for the effective control of non-emissive area formation and growth are proposed. The experiment results based on the designed structure prove that stabilizing and smoothing the interface is the key point to maintain uniformed current density distribution and minimize dark shadow formation in active area.