Organic light emitting display device

1. An organic light emitting display device comprising:

a substrate;

a first pixel disposed over the substrate and configured emit light having a first color; and

a second pixel disposed over the substrate and configured to emit light having a second color different from the first color;

wherein each of the first and second pixels comprises a first electrode disposed over the substrate, a light emission layer formed over the first electrode, an electron transport layer formed over the light emission layer, and a second electrode disposed over the electron transport layer, and

wherein each electron transport layer of the first and second pixels comprises a first electron transport material and a second electron transport material different from the first electron transport material,

wherein a ratio by weight of the first electron transport material to the second electron transport material in the electron transport layer of the first pixel is substantially different from that of the first electron transport material to the second electron transport material in the electron transport layer of the second pixel,

wherein the first electron transport material is Alq3 and the second electron transport material is Liq.

2. The organic light emitting display device of claim 1 , further comprising a third pixel disposed over the substrate and configured to emit light having a third color different from the first and second colors, wherein the first, second and third colors are blue, green, and red, respectively.

3. The organic light emitting display device of claim 2 , wherein a ratio by weight of Alq3 to Liq in the first pixel is about 2:8 to about 5:5.

4. The organic light emitting display device of claim 2 , wherein a ratio by weight of Alq3 to Liq in the second pixel is about 3:7 to about 6:4.

5. The organic light emitting display device of claim 2 , wherein a ratio by weight of Alq3 to Liq in the third pixel is about 4:6 to about 7:3.

6. An organic light emitting display device comprising:

a substrate;

a first pixel disposed over the substrate and configured emit light having a first color; and

a second pixel disposed over the substrate and configured to emit light having a second color different from the first color; and

a third pixel disposed over the substrate and configured to emit light having a third color different from the first and second colors;

wherein each of the first, second and third pixels comprises first and second electrodes formed over the substrate and a light emission layer disposed between the first and second electrodes,

wherein the first, second and third pixels comprise a common electron transport layer extending in each of the first, second and third pixels such that the common electron transport layer is disposed between the light emission layer and the second electrode of each of the first, second and third pixels,

wherein the first pixel comprises an auxiliary electron transport layer that is disposed between the light emission layer and the second electrode of the first pixel,

wherein each of the common electron transport layer and the auxiliary electron transport layer comprises a first electron transport material and a second electron transport material different from the first electron transport material,

wherein a ratio by weight of the first electron transport material to the second electron transport material in the common electron transport layer within the first pixel is substantially different from that of the first electron transport material to the second electron transport material in the auxiliary electron transport layer of the first pixel.

7. The organic light emitting display device of claim 6 ,

wherein the common electron transport layer comprises the first electron transport material of Alq3 and the second electron transport material of Liq, and a ratio by weight of Alq3 to Liq is about 4:6 to about 7:3.

8. The organic light emitting display device of claim 7 , wherein the first second and third colors are blue, green, and red, respectively, wherein the auxiliary electron transport layer of the first pixel comprises the first electron transport material of Alq3 and the second electron transport material of Liq, and a ratio by weight of Alq3 to Liq is about 2:8 to about 5:5.

9. The organic light emitting display device of claim 7 , wherein the first second and third colors are green, blue, and red, respectively, wherein the auxiliary electron transport layer of the first pixel comprises the first electron transport material of Alq3 and the second electron transport material of Liq, and a ratio by weight of Alq3 to Liq is about 3:7 to about 6:4.

10. The organic light emitting display device of claim 6 , wherein the common electron transport layer has a thickness of about 200 Å to about 450 Å.

11. The organic light emitting display device of claim 6 , wherein the auxiliary electron transport layer comprises the first electron transport material of Alq3 and the second electron transport material of Liq.

12. The organic light emitting display device of claim 6 , wherein the first, second and third colors are blue, green, and red, respectively.

13. The organic light emitting display device of claim 6 , wherein the common electron transport layer has a thickness of about 50 Å to about 100 Å.

14. The organic light emitting display device of claim 6 , wherein the common electron transport layer contacts the auxiliary electron transport layer.

15. The organic light emitting display device of claim 6 , wherein the second pixel comprises another auxiliary electron transport layer, wherein the other auxiliary electron transport layer comprises the first electron transport material and the second electron transport material different from the first electron transport material, wherein a ratio by weight of the first electron transport material to the second electron transport material in the other auxiliary electron transport layer is substantially different from that of the first electron transport material to the second electron transport material in each of the common electron transport layer and auxiliary electron transport layer.

16. The organic light emitting display device of claim 6 , wherein the electron transport layer of the first pixel comprises first and second sub-layers, wherein a ratio by weight of the first electron transport material to the second electron transport material in the first sub-layer is substantially different from that of the first electron transport material to the second electron transport material in the second sub-layer.

17. The organic light emitting display device of claim 16 , wherein the electron transport layer of the second pixel and the first sub-layer of the first pixel are integrated in a single common layer such that the ratio by weight of the first electron transport material to the second electron transport material in the first sub-layer of the first pixel is substantially the same as that of the first electron transport material to the second electron transport material in the electron transport layer of the second pixel.