Flexible AM OLED panel driven by bottom-contact OTFTs

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.