Addressing of organic electroluminescent displays

organic electroluminescent compounds are extensively studied around the world. They are mainly studied for flat panel display applications, where organic light emissive diodes form the elementary pixels. OLED-based displays are attractive, because they are lightweight, thin and compact. They do not exhibit viewing angle limitations as LCDs do. In principle they only use one glass plate (or one substrate plate), they need no back-light, no polarisers and no diffuser. Also, OLEDs need no alignment layers and there are no tilt angle requirements as in LCDs. In this paper, we present the major problems and limitations linked to the addressing of matrix-type displays using OLEDs. In particular, we show that active matrix addressing is necessary for high information content (HIC) displays and that for this particular application, polysilicon material is today the only serious candidate for thin film transistor fabrication.