Organic light emitting diode display including capping layer having optical thickness for improving optics

1. An organic light emitting diode (OLED) display, comprising:

a first color pixel, a second color pixel, and a third color pixel on a substrate, each of the first, second, and third color pixels comprising:

a first electrode disposed on the substrate;

an organic emission layer disposed on the first electrode;

a second electrode disposed on the organic emission layer; and

a capping layer disposed on the second electrode,

wherein:

the first color pixel is configured to emit green light, and the second and third color pixels are each configured to emit a color of light other than green;

the organic emission layer of the first color pixel comprises a first emission layer and a second emission layer each being configured to emit light;

the organic emission layer of the second color pixel or the third color pixel comprises a third emission layer configured to emit light;

the second emission layer and the third emission layer comprise both a host and a dopant; and

the first emission layer comprises the host, and does not comprise any dopants therein.

2. The OLED display of claim 1 , wherein a refractive index of the capping layer is in a range of about 1.6 to about 2.6.

3. The OLED display of claim 2 , wherein a physical thickness of the capping layer is in a range of about 600 Å to about 730 Å when the refractive index of the capping layer is about 1.87.

4. The OLED display of claim 2 , wherein the refractive index of the capping layer is measured at a wavelength of about 550 nm.

5. The OLED display of claim 1 , wherein the capping layer comprises an organic material or an inorganic material.

6. The OLED display of claim 5 , wherein the capping layer comprises at least one of a triamine derivative, an arylenediamine derivative, CBP, and tris(8-hydroxyquinoline) aluminum (Alq3).

7. The OLED display of claim 1 , wherein an optical thickness of the capping layer is in a range of about 1100 Å to about 1400 Å.

8. The OLED display of claim 1 , wherein the organic emission layer of the first color pixel further comprises:

a hole injection layer and a hole transporting layer disposed on the first electrode; and

an electron transporting layer and an electron injection layer.

9. The OLED display of claim 8 , wherein:

the first emission layer contacts the hole injection layer or the hole transporting layer; and

the second emission layer contacts the electron transporting layer or the electron injection layer.

10. The OLED display of claim 9 , wherein:

the organic emission layer of the first color pixel further comprises another first emission layer; and

the second emission layer is disposed between the first emission layer and the another first emission layer.

11. The OLED display of claim 10 , wherein the second emission layer is disposed in a center region of the organic emission layer of the first color pixel.

12. The OLED display of claim 10 , wherein:

the first emission layer disposed on the second emission layer contacts the hole injection layer or the hole transporting layer; and

the another first emission layer disposed under the second emission layer contacts the electron transporting layer or the electron injection layer.

13. The OLED display of claim 1 , wherein:

the organic emission layer of the first color pixel further comprises another first emission layer; and

the second emission layer is disposed between the first emission layer and the another first emission layer.