OLEDs having inorganic material containing anode capping layer

1. An organic light emitting device comprising:

a cathode;

a layer including an organic electroluminescent material;

a layer including an electron accepting material;

an anode capping layer comprising a mixture of inorganic material and organic material;

an anode; and

a substrate in the sequence before the cathode or after the anode,

wherein the anode capping layer is selected to provide the device with a luminance stability ratio that is greater than 1.

2. The device of claim 1 , wherein the anode comprises indium tin oxide.

3. The device of claim 1 , wherein the inorganic material is an inorganic metal containing material.

4. The device of claim 1 , wherein the inorganic material is an elemental metal, or a metal alloy, or a mixture of the elemental metal and the metal alloy.

5. The device of claim 1 , wherein the inorganic material is an elemental metal, or a metal alloy, or a mixture of the elemental metal and the metal alloy, wherein the elemental metal and the metals of the metal alloy are selected from the group consisting of Mg, Cr, Au, and Pd.

6. The device of claim 1 , wherein the electron accepting material is selected from the group consisting of: tetracyanoquinodimethane compounds; thiopyranylidine compounds; polynitrofluorenone compounds; tetracyanoethylene compounds; chloranil compounds; carboxylfluorenone malonitrile compounds; N,N′bis(dialkyl)-1,4,5,8-naphthalenetetracarboxylic diimide compounds; N,N bis(diaryl)-1,4,5,8-naphthalenetetracarboxylic diimide compounds; carboxybenzylnaphthaquinone compounds; diphenoquionone compounds, inorganic Lewis acid compounds, and fullerene compounds, and a mixture thereof.

7. The device of claim 1 , wherein the layer including an electron accepting material further includes an organic material.

8. The device of claim 1 , wherein the electroluminescent layer is capable of emitting blue light.

9. The device of claim 1 , wherein the electroluminescent layer is capable of emitting red light.

10. The device of claim 1 , wherein the electroluminescent layer is capable of emitting green light.

11. The device of claim 1 , wherein the electroluminescent layer is capable of emitting white light.

12. The device of claim 1 , wherein the anode capping layer is selected such that the luminance stability ratio is greater than about 2.

13. The device of claim 1 , wherein the anode capping layer is selected such that the luminance stability ratio is greater than about 5.

14. The device of claim 1 , wherein the anode capping layer is selected such that the luminance stability ratio is greater than about 10.

15. The organic light emitting device of claim 1 , wherein the anode capping layer is a multilayer structure comprising one layer of inorganic material and one layer of organic material.

16. The organic light emitting device of claim 15 , wherein the inorganic material is one selected from the group consisting of Mg, Ca and mixture thereof.

17. The organic light emitting device of claim 16 , wherein the organic material comprises NPB.

18. The organic light emitting device of claim 17 , wherein the NPB layer is doped with F 4 TCNQ.

19. The device of claim 1 , wherein the inorganic material is one selected from the group consisting of C, Ge, Si, SiO 2 , Si 3 N 4 , metal hydroxides, metal halides, metal sulfides, and metal nitrides.

20. An organic light emitting device comprising:

a cathode;

a layer including an organic electroluminescent material;

a layer including an electron accepting material;

an anode capping layer including a mixture of an organic material and of an elemental metal, or a metal alloy, or a mixture of the elemental metal and the metal alloy;

an anode; and

a substrate in the sequence before the cathode or after the anode,

wherein the anode capping layer is selected to provide the device with a luminance stability ratio that is greater than 1.

21. The device of claim 20 , wherein the anode comprises indium tin oxide.

22. The device of claim 20 , wherein the elemental metal and the metals of the metal alloy are selected from the group consisting of Mg, Cr, Au, and Pd.

23. The device of claim 20 , wherein the electron accepting material is selected from the group consisting of: tetracyanoquinodimethane compounds; thiopyranylidine compounds; polynitrofluorenone compounds; tetracyanoethylene compounds; chloranil compounds; carboxylfluorenone malonitrile compounds; N,N′bis(dialkyl)-1,4,5,8-naphthalenetetracarboxylic diimide compounds; N,N′bis(diaryl)-1,4,5,8-naphthalenetetracarboxylic diimide compounds; carboxybenzylnaphthaquinone compounds; diphenoquionone compounds, inorganic Lewis acid compounds, and fullerene compounds, and a mixture thereof.

24. The device of claim 20 , wherein the layer including an electron accepting material further includes an organic material.

25. The device of claim 20 , wherein the electroluminescent layer is capable of emitting blue light.

26. The device of claim 20 , wherein the electroluminescent layer is capable of emitting red light.

27. The device of claim 20 , wherein the electroluminescent layer is capable of emitting green light.

28. The device of claim 20 , wherein the electroluminescent layer is capable of emitting white light.

29. The device of claim 20 , wherein the anode capping layer is selected such that the luminance stability ratio is greater than about 2.

30. The device of claim 20 , wherein the anode capping layer is selected such that the luminance stability ratio is greater than about 5.

31. The device of claim 20 , wherein the anode capping layer is selected such that the luminance stability ratio is greater than about 10.

32. An organic light emitting device comprising:

a cathode;

a layer including an organic electroluminescent material;

a multilayer anode capping layer comprising one layer of a mixture of an inorganic material selected from the group consisting of Mg, Ca, and mixture thereof, and of F 4 TCNQ doped NPB; and

an anode,

wherein the anode capping layer is selected to provide the device with a luminance stability ratio that is greater than 1.