White organic light emitting device and color display apparatus employing the same

1. A white organic light emitting device (OLED), comprising:

a substrate;

a reflective electrode formed on the substrate;

an organic light emitting layer formed on the reflective electrode, the organic light emitting layer emitting white light; and

a semi-transparent electrode formed on the organic light emitting layer,

wherein optical thicknesses of the organic light emitting layer and the semi-transparent electrode are configured such that a longest resonance wavelength between the reflective electrode and the semi-transparent electrode is shorter than a shortest wavelength in a visible light region of a white light spectrum generated in the organic light emitting layer, the longest resonance wavelength is 400 nm or less.

2. The white OLED of claim 1 , in which a reflectivity of the semi-transparent electrode is within a range of 0.1% to 50% with respect to white light.

3. The white OLED of claim 2 , in which the reflectivity of the semi-transparent electrode is within a range of 10 to 50% with respect to white light.

4. The white OLED of claim 1 , in which the reflective electrode has one of a transparent conductive oxide/metal/transparent conductive oxide structure and a metal/transparent conductive oxide structure.

5. The white OLED of claim 4 , in which the transparent conductive oxide comprises one of an indium tin oxide (ITO) and an indium zinc oxide (IZO).

6. The white OLED of claim 1 , further including a capping layer formed on the semi-transparent electrode and formed of a transparent dielectric material having a refractive index within a range of 1.4 to 2.4.

7. The white OLED of claim 1 , further comprising an optical path control layer that is formed on the semi-transparent electrode, to form an additional resonator in cooperation with the reflective electrode and the semi-transparent electrode.

8. The white OLED of claim 7 , in which the optical path control layer is formed of a material having a light transmittivity of 90% or greater in a visible light region.

9. The white OLED of claim 8 , in which the optical path control layer is formed of at least one combination selected from a group consisting of Al 2 O 3 , BaO, MgO, HfO 2 , ZrO 2 , CaO 2 , SrO 2 , Y 2 O 3 , Si 3 N 4 , AlN, GaN, ZnS, and CdS.

10. The white OLED of claim 7 , further comprising a dielectric mirror layer on an upper surface of the optical path control layer.

11. The white OLED of claim 7 , further comprising a metal mirror layer on an upper surface of the optical control layer.

12. The white OLED of claim 1 , in which the organic light emitting layer comprises a hole injection layer, a hole transporting layer, a white light emitting layer, an electron transporting layer, and an electron injection layer sequentially stacked on the reflective electrode, and the reflective electrode is an anode, and the semi-transparent electrode is a cathode.

13. The white OLED of claim 1 , in which the organic light emitting layer comprises an electron injection layer, an electron transporting layer, a white light emitting layer, a hole transporting layer, and a hole injection layer sequentially stacked on the reflective electrode, with the reflective electrode being a cathode and the semi-transparent electrode being an anode.

14. A color display apparatus, comprising:

a bottom substrate;

a plurality of reflective electrodes formed on the bottom substrate;

an organic light emitting layer formed on the reflective electrodes, the organic light emitting layer emitting white light;

a semi-transparent electrode formed on the organic light emitting layer;

a top substrate disposed to face the semi-transparent electrode; and

a plurality of color filters formed in positions corresponding to the reflective electrodes on a lower surface of the top substrate,

wherein optical thicknesses of the organic light emitting layer and the semi-transparent electrode are configured such that a longest resonance wavelength between the reflective electrodes and the semi-transparent electrode is shorter than a shortest wavelength in a visible light region of a white light spectrum generated in the organic light emitting layer, the longest resonance wavelength is 400 nm or less.

15. The color display apparatus of claim 14 , in which a reflectivity of the semi-transparent electrode is within a range of 0.1 to 50% with respect to white light.

16. The color display apparatus of claim 15 , in which the reflectivity of the semi-transparent electrode is within a range of 10 to 50% with respect to white light.

17. The color display apparatus of claim 14 , in which the reflective electrode has one of a transparent conductive oxide/metal/transparent conductive oxide structure and a metal/transparent conductive oxide structure.

18. The color display apparatus of claim 14 , further including a capping layer formed on the semi-transparent electrode and formed of a transparent dielectric material having a refractive index within a range of 1.4 to 2.4.

19. The color display apparatus of claim 14 , further comprising an optical path control layer that is formed on the semi-transparent electrode, to form an additional resonator in cooperation with the reflective electrode and the semi-transparent electrode.

20. The color display apparatus of claim 19 , in which the optical path control layer is formed of a material having a light transmittivity of 90% or greater in a visible light region.