Flat panel display with high efficiency and method of fabricating the same

1. An organic light emitting device, comprising:

red (R), green (G), and blue (B) lower electrodes formed on a substrate, the R, G, B lower electrodes each having an equal thickness;

R, G, B organic thin film layers formed on the R, G, B lower electrodes, respectively; and

an upper electrode formed over the substrate, the upper electrode comprising a first upper electrode layer and a second upper electrode layer,

wherein at least a portion of the upper electrode, corresponding to one of the R, G, B organic thin film layers, has a different thickness from other portions of the upper electrode,

wherein the upper electrode corresponds to a side of the organic light emitting device from which light is emitted, and

wherein the first upper electrode layer has a uniform thickness, and the second upper electrode layer is comprised of transparent materials, and

wherein the second upper electrode layer is comprised of at least one or more materials selected from IZO and ITO.

2. The organic light emitting device of claim 1 ,

wherein the first upper electrode layer is formed over the substrate; and

the second upper electrode layer is formed on the first upper electrode layer,

wherein at least a portion of the second upper electrode layer, corresponding to one of the R, G, B organic thin film layers, has a different thickness from other portions of the second upper electrode layer.

3. The organic light emitting device of claim 2 , wherein the first upper electrode layer is comprised of at least one or more materials selected from LiF and Mg:Ag.

4. The organic light emitting device of claim 1 ,

wherein the first upper electrode layer is formed over the substrate; and

the second upper electrode layer is formed on the first upper electrode layer,

wherein portions of the second upper electrode layer corresponding to the R, G, B organic thin film layers each have a different thickness.

5. The organic light emitting device of claim 4 , wherein the first upper electrode layer is comprised of at least one or more materials selected from LiF and Mg:Ag.

6. The organic light emitting device of claim 4 , wherein the second upper electrode layer has a thickness of approximately 800 Å to approximately 2400 Å.

7. The organic light emitting device of claim 6 , wherein the second upper electrode layer has a thickness of approximately 800 Å to approximately 1600 Å to obtain a high luminous efficiency.

8. The organic light emitting device of claim 6 , wherein the second upper electrode layer has a thickness of approximately 800 Å to approximately 2400 Å to obtain a high color purity.

9. The organic light emitting device of claim 4 , wherein the portion of the second upper electrode layer, corresponding to the R organic thin film layer, has a thickness in the range of approximately 1200 Å to approximately 2400 Å.

10. The organic light emitting device of claim 4 , wherein the portion of the second upper electrode layer, corresponding to the G organic thin film layer, has a thickness of approximately 800 Å.

11. The organic light emitting device of claim 4 , wherein the portion of the second upper electrode layer, corresponding to the B organic thin film layer, has a thickness of approximately 1600 Å.

12. The organic light emitting device of claim 1 ,

wherein the first upper electrode layer is formed over the substrate; and

the second upper electrode layer is formed on the first upper electrode layer, the second upper electrode layer having portions of different thicknesses which correspond to the R, G, B organic thin film layers,

wherein the second upper electrode layer includes:

first layers for R, G, B unit pixels, the first layers independently formed in different thicknesses on respective portions of the first upper electrode layer that correspond to the R, G, B organic thin film layers; and

a second layer formed in a uniform thickness on the first layers and the first upper electrode layer.

13. The organic light emitting device of claim 12 , wherein the first upper electrode layer is comprised of at least one or more materials selected from LiF and Mg:Ag.

14. The organic light emitting device of claim 12 , wherein the sum of the thickness of any one of the first layers and the thickness of the second layer of the second upper electrode layer is approximately 800 Å to 2400 Å.

15. The organic light emitting device of claim 1 ,

wherein the first upper electrode layer is formed over the substrate; and

the second upper electrode layer is formed on the first upper electrode layer, the second upper electrode layer I having portions of different thicknesses which correspond to the R, G, B organic thin film layers,

wherein the second upper electrode layer includes:

a first layer formed on the first upper electrode layer in a uniform thickness; and

second layers for the R, G, B unit pixels, each of the second layers independently formed in a different thickness on respective portions of the first layer that correspond to the R, G, B organic thin film layers.

16. The organic light emitting device of claim 15 , wherein the first upper electrode layer is comprised of at least one or more materials selected from LiF and Mg:Ag.

17. The organic light emitting device of claim 15 , wherein the sum of the thickness of the first layer and the thickness of any one of the second layers of the second upper electrode layer is approximately 800 Å to 2400 Å.

18. The organic light emitting device of claim 1 , wherein the substrate corresponds to a side of the organic light emitting device from which light is not emitted.

19. The organic light emitting device of claim 1 , wherein the upper electrode covers the R, G, B lower electrodes.