Field of the Invention
The present invention relates to an organic light emitting device, and more particularly, to a white organic light emitting device in which a lifetime of a device is enhanced.
Discussion of the Related Art
Recently, as society advances to the information-oriented society, the field of display apparatuses, which visually express an electrical information signal, is rapidly advancing. Flat panel display (FPD) apparatuses, having excellent performance in terms of thinness, lightness, and low power consumption, have been developed.
Examples of the FPD apparatuses include LCD apparatuses, plasma display panel (PDP) apparatuses, field emission display (FED) apparatuses, organic light emitting display apparatuses, etc.
In particular, the organic light emitting display apparatuses are self-emitting devices. In comparison with other FPD apparatuses, the organic light emitting display apparatuses have a fast response time, high emission efficiency, high luminance, and a wide viewing angle.
An organic light emitting device includes an organic emission layer which is formed between two electrodes. Electrons and holes are injected from the two electrodes into the organic emission layer, and an exciton is generated by combining a electron with a hole. The organic light emitting device is a device using the principle that light is emitted when the generated exciton is dropped from an excited state to a ground state.
A related art organic light emitting display apparatus includes a blue emission layer formed of a fluorescent material, for realizing white. However, a quantum efficiency of an emission layer formed of a fluorescent material theoretically is about 25% of a quantum efficiency of an emission layer formed of a phosphorescence material. For this reason, the blue emission layer formed of a fluorescent material cannot show sufficient luminance in comparison with a phosphorescence material.