Active matrix organic electroluminescent display device and method of fabricating the same

1. An active matrix organic electroluminescent display device, comprising:

a substrate including a light emitting region having sub pixel regions;

a plurality of switching elements on the substrate in the sub pixel regions;

a first passivation layer covering the plurality of switching elements and having a plurality of first contact holes exposing the plurality of switching elements;

a plurality of first electrodes on the first passivation layer, each first electrode connected to each switching element through each first contact hole;

a second passivation layer on the plurality of first electrodes, the second passivation layer having a plurality of openings exposing the plurality of first electrodes and an end portion covering edge portions of the plurality of first electrodes;

a plurality of organic electroluminescent layers on the second passivation layer, each organic electroluminescent layer contacting each first electrode through each opening; and

a second electrode on the plurality of organic electroluminescent layers,

wherein the first passivation layer is made of a first organic material having a planarized upper surface and the second passivation layer is made of a second organic material having a formation temperature lower than a formation temperature of the first organic material, and the end portion of the second passivation is disposed between a terminal end portion of each of the plurality of organic electroluminescent layers and a terminal end portion of each of the plurality of first electrodes.

2. The device according to claim 1 , wherein the first organic material includes at least one of benzocyclobutene, polyacrylate, and polyimide.

3. The device according to claim 2 , wherein the polyimide has an imidization rate of more than about 95%.

4. The device according to claim 1 , wherein the second organic material includes at least one of photoresist, benzocyclobutene, polyacrylate, and polyimide.

5. The device according to claim 4 , wherein the polyimide has an imidization rate of more than about 95%.

6. The device according to claim 1 , wherein the plurality of first electrodes function as an anode electrode and the second electrode functions as a cathode electrode.

7. The device according to claim 6 , wherein light produced by the organic electroluminescent layer is transmitted through the second electrode.

8. The device according to claim 7 , wherein the second electrode includes transparent conducting material.

9. The device according to claim 1 , wherein each switching element includes a semiconductor layer having an active region and source and drain regions, a gate electrode disposed over the active region, a source electrode connected to the source region, and a drain electrode connected to the drain region.

10. The device according to claim 9 , further comprising a plurality of storage capacitors electrically connected to the plurality of switching elements.

11. The device according to claim 10 , wherein each storage capacitor includes a first capacitor electrode made of the same material as the semiconductor layer and a second capacitor electrode connected to the source electrode.

12. The device according to claim 1 , wherein the first and second passivation layers are formed by a spin coating method.

13. The device according to claim 1 , wherein the first passivation layer has a thickness within a range of about 1 μm to about 10 μm.

14. The device according to claim 1 , wherein the first and second passivation layers are made of different organic materials.

15. A method of fabricating an active matrix organic electroluminescent display device, comprising steps of:

forming a switching element on a substrate having sub pixel regions;

forming a first passivation layer of a first organic material on the switching element, the first passivation layer includes a first contact hole to expose the switching element;

forming a first electrode on the first passivation layer in the sub pixel regions, the first electrode connected to the switching element through the first contact hole;

forming a second passivation layer of a second organic material on the first electrode, the second passivation layer having an opening to expose the first electrode and an end portion covering edge portions of the first electrode;

forming an organic electroluminescent layer on the second passivation layer in the sub pixel regions, the organic electroluminescent layer contacting the first electrode through the opening; and

forming a second electrode on the organic electroluminescent layer,

wherein the first passivation layer includes a first organic material having a planarized upper surface and the second passivation layer includes a second organic material having a formation temperature lower than a formation temperature of the first organic material, and the end portion of the second passivation is disposed between a terminal end portion of each of the plurality of organic electroluminescent layers and a terminal end portion of each of the plurality of first electrodes.

16. The method according to claim 15 , wherein the first and second passivation layers are formed by a spin coating method.

17. The method according to claim 15 , wherein one of the first and second organic materials include polyimide.

18. The method according to claim 17 , wherein the polyimide has an imidization rate of more than about 95%.

19. The method according to claim 15 , wherein the switching element includes a semiconductor layer having an active region and source and drain regions, a gate electrode disposed over the active region, a source electrode connected to the source region, and a drain electrode connected to the drain region.

20. The method according to claim 19 , further comprising forming a storage capacitor electrically connected to the switching element.

21. The method according to claim 20 , wherein the storage capacitor includes a first capacitor electrode made of the same material as the semiconductor layer and a second capacitor electrode connected to the source electrode.

22. The method according to claim 15 , wherein the first passivation layer has a thickness within a range of about 1 μm to about 10 μm.

23. The method according to claim 15 , wherein the first and second passivation layers are made of different organic materials.