Organic LED device with electrodes having reduced resistance

1. An organic electroluminescent device with a layer stack for emitting light through a top electrode which is at least partly transparent, the organic electroluminescent device comprising:

a conductive foil comprising a substrate having an upper side and a lower side, and a first metal layer located on the upper side of the substrate, wherein a sheet resistance of the first metal layer is less than 0.05 Ω/square, wherein the first metal layer comprises a first metal area and a second metal area, the first metal area being electrically insulated from the second metal area, and wherein the first metal area acts as a bottom electrode;

an organic layer stack deposited on top of the bottom electrode and configured to emit light, wherein the top electrode is located on top of the organic layer stack; and

an at least partly transparent protection element covering at least the top electrode and the organic layer stack;

wherein the conductive foil comprises a second metal layer and a conducting path, the second metal layer having a sheet resistance of less than 0.05 Ω/square and being located on the lower side of the substrate, and

wherein the conducting path is in the substrate and connects the second metal layer to the second metal area of the first metal layer, and wherein the second metal area is directly connected to the top electrode.

2. The organic electroluminescent device according to claim 1 , wherein the first metal layer further comprises a conducting diffusion barrier layer at an interface with the organic layer stack.

3. The organic electroluminescent device according to claim 1 , wherein the transparent top electrode is made of indium-tin-oxide.

4. The organic electroluminescent device according to claim 1 , wherein the top electrode has a thickness below 20 nm and comprises a top metal layer and an electron injection layer at an interface with the organic layer stack.

5. The organic electroluminescent device according to claim 1 , wherein the organic layer stack is patterned into sub-areas in order to form light-emitting sub-tiles which are separated from each other by non-emitting areas so as to provide conducting metal tracks to each of the sub-tiles.

6. The organic electroluminescent device according to claim 1 , wherein the first metal area and the second metal area of the first metal layer are separated by an insulating filling material.

7. The organic electroluminescent device according to claim 1 , wherein the conductive foil is a flexible conductive foil comprising a flexible carrier material.

8. The organic electroluminescent device according to claim 1 , wherein the at least partly transparent protection element comprises a transparent, chemically inert layer covering at least the top electrode and the organic layer stack.

9. The organic electroluminescent device according to claim 1 , wherein at least the first metal layer comprises copper.

10. A method of forming an organic electroluminescent device having an organic layer stack configured to emit light between a top electrode and a bottom electrode, the method comprising the acts of:

providing a conductive foil by gluing a first metal layer on a first side of a substrate, the first metal layer having a sheet resistance of less than 0.05 Ω/square, wherein the first metal layer comprises a first metal area and a second metal area, the first metal area being electrically insulated from the second metal area, and wherein the first metal area acts as a bottom electrode;

forming the organic layer stack on top of the bottom electrode; and

forming an at least partly transparent protection element covering at least the top electrode and the organic layer stack.

11. The method of claim 10 , wherein the providing act further comprises the acts of:

gluing a second metal layer on a second side of the substrate, the second side being opposite the first side, wherein the second metal layer has a sheet resistance of less than 0.05 Ω/square; and

forming a conducting path in the substrate for connecting the second metal layer to the second metal area of the first metal layer.

12. The method of claim 11 , wherein the second metal area is directly connected to the top electrode.

13. The method of claim 10 , wherein the conductive foil is flexible.

14. The method of claim 10 , wherein the providing act further comprises the act of forming a conducting diffusion barrier layer between the bottom electrode and the organic layer stack.