Thin film encapsulation of OLED displays with organic-inorganic composite film

Abstract

Organic Light-Emitting diode (OLED) display is considered as one of the most potential display technology. Since it has the advantages of low-driving voltage, high luminance and high efficiency, the OLED can perform large area panel full-color display and flexible organic electroluminescent display. OLED display has been extensively studied and become a hot spot in international research recently. However, the short operation lifetime due to the sensitivity to vapor and oxygen limits the process of OLED technology to industrialization. Hence effective encapsulation technology is the best way to solve the problem. High-performance Thin Film Encapsulation (TFE) should be fabricated to realize long-time driving OLED display. First, a high-quality TFE should have a good diffusion barrier to water and oxygen penetration, high flexibility or mechanically robust to avoid cracking during bending. Secondly, a TFE should have good heat diffusion effect. This is because the device may degrade when the current is turn on, resulting from the electro-chemical process. The heat accumulation will promote the growth of pinhole in the cathode area and the formation of darkspot in the emissive layer. Finally, damage effect on device should be lower enough to avoid the degradation of organic layers during passivation deposition, since the organic materials cannot withstand high process temperature and also require an inert processing environment. OLED displays can be fabricated as thin as the substrate if thin film packaging is used. We propose a novel multilayer stack of organic-inorganic composite film encapsulation. The results on the barrier properties of this stack and a working passive matrix polymer OLED demonstrator are presented. The focus of this paper is to investigate the relationship between deposition parameters and its properties in order to prepare excellent organic-inorganic composite film for OLED. The compatibility with the OLED structure itself and results on device operation will be shown. By analyzing the observation and data, the influence of deposition parameters of organic-inorganic composite film for OLED is systematically discussed. At last, more tests are needed in order to get a more precise investigation.