Organic electroluminescent device

1. An organic electroluminescent device comprising an electroluminescent layer stack on top of a substrate, where the electroluminescent layer stack comprises an organic light-emitting layer stack with one or more organic layers sandwiched between a first electrode facing towards the substrate and a second electrode, where the second electrode comprises a layer stack of at least a transparent conductive protection layer on top of the organic light-emitting layer stack, a transparent organic conductive buckling layer disposed on top of the transparent conductive protection layer, the transparent organic conductive buckling layer having a glass transition temperature lower than the lowest glass transition temperature of the organic layers within the organic light-emitting layer stack, and a reflective stress inducing layer on top of the buckling layer to introduce stress to the buckling layer.

2. The organic electroluminescent device as claimed in claim 1 , wherein the stress inducing layer is an aluminum layer.

3. The organic electroluminescent device as claimed in claim 2 , wherein the stress inducing layer has a thickness larger than 5 nm.

4. The organic electroluminescent device as claimed in claim 2 , wherein the protection layer comprises a metal oxide.

5. The organic electroluminescent device as claimed in claim 2 , wherein the protection layer has a thickness larger than 20 nm.

6. The organic electroluminescent device as claimed in claim 2 , wherein the buckling layer has a glass transition temperature which is at least 30° C. less than the lowest glass transition temperature of the organic layers within the organic light-emitting layer stack.

7. The organic electroluminescent device as claimed in claim 2 wherein the buckling layer comprises a suitable amount of conductive material doped to the buckling layer in order to enhance the electrical conductivity of the buckling layer.

8. The organic electroluminescent device as claimed in claim 2 wherein the buckling layer has a layer thickness of more than 20 nm.

9. The organic electroluminescent device as claimed in claim 2 , wherein the second electrode further comprises a stress enhancement layer deposited on top of the stress inducing layer having a larger internal stress than the stress inducing layer.

10. The organic electroluminescent device as claimed in claim 9 , wherein the stress enhancement layer is a metal layer made of Mn, Cu, Cr or mixtures thereof.

11. The organic electroluminescent device as claimed in claim 10 , wherein a current distribution layer is deposited on top of the second electrode, and wherein the current distribution layer comprises aluminum or copper.

12. A method to manufacture an organic electroluminescent device as claimed in claim 1 , comprising:

depositing the second electrode comprising a layer stack of at least a transparent conductive protection layer, a transparent organic conductive buckling layer and a stress inducing layer, on top of the organic light-emitting layer stack, and

heating the electroluminescent layer stack to a temperature, which is above the glass transition temperature of the buckling layer and below the lowest glass transition temperature of the organic layers within the organic light-emitting layer stack for a time period sufficient to obtain buckles within the buckling layer.

13. The method as claimed in claim 12 , further comprising the step of stamping the buckling layer with a pre-shaped buckling tool during the heating step in order to introduce buckles into the buckling layer.

14. The method as claimed in claim 12 , further comprising the step of depositing a stress enhancement layer on top of the stress inducing layer before heating the electroluminescent layer stack.

15. The method as claimed in claim 14 , further comprising the step of thickening the second electrode by depositing a current distribution layer on top of the second electrode after the heating step.

16. The organic electroluminescent device as claimed in claim 2 , wherein the stress inducing layer has a thickness between 10 nm and 25 nm.

17. The organic electroluminescent device as claimed in claim 2 , wherein the buckling layer has a layer thickness between 50 nm and 100 nm.

18. A device, comprising:

a first electrode disposed on a substrate;

an organic light-emitting layer stack disposed on the first electrode, wherein the organic light-emitting layer stack includes one or more organic layers; and

a second electrode disposed on the organic light-emitting layer stack, wherein the second electrode comprises:

a transparent conductive protection layer disposed on the organic light-emitting layer stack,

a transparent organic conductive buckling layer disposed on the protection layer, wherein the transparent organic conductive buckling layer has a plurality of buckles formed therein and has a glass transition temperature which is less than the lowest glass transition temperature of the organic layers within the organic light-emitting layer stack, and

a stress inducing layer disposed on the buckling layer.

19. The device of claim 18 , wherein the buckling layer has a glass transition temperature that is at least 30° C. less than the lowest glass transition temperature of the organic layers within the organic light-emitting layer stack.

20. The device of claim 18 , further comprising a current distribution layer disposed on the second electrode, wherein the current distribution layer comprises aluminum or copper.