Fabrication of 5.8-in. OTFT-driven flexible color AMOLED display using dual protection scheme for organic semiconductor patterning

A 5.8-in. wide-QQVGA flexible color active-matrix organic light-emitting-diode (AMOLED) display consisting of organic thin-film transistors (OTFTs) and phosphorescent OLEDs was fabricated on a plastic film. To reduce the operating voltage of the OTFTs, Ta2O5 with a high dielectric constant was employed as a gate insulator. Pentacene was used for the semiconductor layer of the OTFTs. This layer was patterned by photolithography and dry-etched using a dual protection layer of poly p-xylylene and SiO2 film. Uniform transistor performance was achieved in the OTFT backplane with QQVGA pixels. The RGB emission layers of the pixels were formed by vacuum deposition of phosphorescent small molecules. The resulting display could clearly show color moving images even when it was bent and operated at a low driving voltage (below 15 V).