Organic light emitting diode device and method of manufacturing the same

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

a substrate,

a first electrode on top of the substrate,

a buffer layer on top of the first electrode,

an emission layer on top of the buffer layer, and

a second electrode on top of the emission layer,

wherein the buffer layer includes:

a transparent conductive oxide, and

a metal or metal oxide having a work function lower than a work function of the transparent conductive oxide.

2. The OLED device as claimed in claim 1 , wherein the transparent conductive oxide has a work function of about 3.0 to about 5.0 eV.

3. The OLED device as claimed in claim 2 , wherein the transparent conductive oxide includes an oxide of at least one of indium, zinc, and tin.

4. The OLED device as claimed in claim 1 , wherein the metal or metal oxide has a work function of about 2 to about 4 eV.

5. The OLED device as claimed in claim 4 , wherein the buffer layer includes the metal, the metal including at least one of calcium, magnesium, samarium, cesium, barium, strontium, yttrium, and lanthanum.

6. The OLED device as claimed in claim 4 , wherein the buffer layer includes the metal oxide, the metal oxide including an oxide of at least one of calcium, magnesium, samarium, cesium, barium, strontium, yttrium, and lanthanum.

7. The OLED device as claimed in claim 1 , wherein the metal or metal oxide is included in an amount of about 0.5 wt % to about 20 wt % based on a total weight of the buffer layer.

8. The OLED device as claimed in claim 1 , wherein the buffer layer has a work function of about 3.6 eV to about 4.7 eV.

9. The OLED device as claimed in claim 1 , wherein the buffer layer has a transmittance of about 80% or greater at a wavelength of about 400 nm to about 700 nm.

10. The OLED device as claimed in claim 1 , wherein the buffer layer has a thickness of about 0.1 Å to about 1000 Å.

11. A method of manufacturing an organic light emitting diode (OLED) device, the method comprising

forming a first electrode on a substrate,

forming a buffer layer on the first electrode,

forming an emission layer on the buffer layer, and

forming a second electrode on the emission layer,

wherein the buffer layer includes:

a transparent conductive oxide, and

a metal or metal oxide having a work function lower than a work function of the transparent conductive oxide.

12. The method as claimed in claim 11 , wherein the buffer layer includes the metal, the metal including at least one of calcium, magnesium, samarium, cesium, barium, strontium, yttrium, and lanthanum.

13. The method as claimed in claim 11 , wherein the buffer layer includes the metal oxide, the metal oxide including an oxide of at least one of calcium, magnesium, samarium, cesium, barium, strontium, yttrium, and lanthanum.

14. The method as claimed in claim 11 , wherein forming the buffer layer includes sputtering, evaporating, or wet coating.

15. The method as claimed in claim 11 , wherein forming the buffer layer includes co-sputtering using a target of transparent conductive oxide and a target of metal or metal oxide.

16. The method as claimed in claim 15 , wherein oxygen gas is supplied during the sputtering.

17. The method as claimed in claim 16 , wherein the oxygen gas is supplied at a flow rate of about 0.01 sccm to about 1 sccm.

18. The method as claimed in claim 11 , wherein the buffer layer has a work function of about 3.6 eV to about 4.7 eV and a transmittance of about 80% or greater at a wavelength region of about 400 nm to about 700 nm.

19. The method as claimed in claim 18 , wherein the metal or metal oxide has a work function of about 2 eV to about 4 eV.

20. The method as claimed in claim 19 , wherein the transparent conductive oxide has a work function of about 3.0 eV to about 5.0 eV.