a-Si:H TFT phosphorescent OLED active matrix pixels fabricated on polymeric substrates

Organic light emitting diode (OLED) displays fabricated on polymeric substrates would be lightweight, flexible, rugged, and potentially less expensive to manufacture. Several passive matrix OLED displays fabricated on polymeric substrates have been demonstrated. For high information content displays, active-matrix pixel addressing provides improved display performance and reduced power consumption. To date, all active matrix OLED displays have been fabricated on rigid substrates and most used polysilicon thin film transistors (TFTs) as the active elements because they can provide sufficient current at low voltages and acceptable device dimensions. However, improvements in the efficiency of OLEDs allows lower mobility TFTs, such as those based on hydrogenated amorphous silicon (a-Si:H) or even organic semiconductors, to be used as OLED drive devices (M.A. Baldo et al, Appl. Phys. Lett., vol. 75, pp. 4-6, 1999). The lower processing temperatures of a-Si:H and organic TFTs may permit the use of polymeric substrates. In this work, 1 mm² a-Si:H TFT phosphorescent OLED active matrix pixels and pixel arrays were fabricated on 50 μm thick polyimide substrates.