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White phosphorescent light emission from polymer light-emitting devices (PLEDs) has been demonstrated. To fabricate the white-emitting PLED, blue phosphorescent polymer (BPP) and red phosphorescent polymer (RPP) were used for the emissive layer, and the emission color was tuned by controlling the concentration ratio of BPP to RPP. The external quantum efficiency of the white-emitting PLED, with CIE coordinates of (0.34, 0.36), was 6.0% at luminance of 100 cd/m2. To investigate the emission mechanism in the PLED, its photoluminescence spectrum and transient decay were measured. These experimental measurements indicate that direct excitation of the iridium-complex (Ir-complex) units by carrier trapping is a major excitation process for white-emitting PLED. A 3.6-in full-color display based on the white phosphorescent PLED and color filters was demonstrated. [ABSTRACT FROM PUBLISHER]

Active matrix organic-light-emitting-diode (AM OLED) panels, driven by organic thin-film transistors (OTFT), have been successfully fabricated on a flexible plastic substrate. The pixel circuit consists of two bottom-contact pentacene OTFTs working as switching and driving transistors. The panel has 16 × 16 pixels, each of which have an OLED using a phosphorescent material with an emission efficiency of 30 cd/A. A tantalum oxide (Ta2O5) film with a dielectric constant of 24, prepared by the anodization of Tantalum (Ta), was used as the gate insulator of the OTFTs. The passivation layer on the OTFTs was formed by a layer of silicon dioxide (SiO2) and two layers of polyvinyl alcohol. Using OTFTs with a Ta2O5 gate insulator, the authors have realized a flexible active matrix OLED panel driven with a low voltage of -12 V. [ABSTRACT FROM AUTHOR]