Organic electroluminescent device

1 . An organic electroluminescent device comprising:

a substrate;

an anode on the substrate;

an organic electroluminescent material layer on the anode; and

a multi-layer transparent cathode on the organic electroluminescent layer, the transparent cathode comprising:

a thin metal layer in the bottom of the transparent cathode;

a doped buffer layer on the thin metal layer; and

a transparent electrode on the doped buffer layer.

2 . The organic electroluminescent device as claimed in claim 1 , wherein the doped buffer layer comprises electron transport materials.

3 . The organic electroluminescent device as claimed in claim 2 , wherein the doped buffer layer comprises tris(8-quinolinato-N1,08)-aluminum (Alq3) or bis(10-hydroxyben-zo[h]quinolinato) beryllium (Bebq2).

4 . The organic electroluminescent device as claimed in claim 2 , wherein the dopant of the doped buffer layer comprise metal materials.

5 . The organic electroluminescent device as claimed in claim 4 , wherein the metal materials have a work function of less than or equal to 4.2 electron volts (eV).

6 . The organic electroluminescent device as claimed in claim 5 , wherein the metal materials are selected from alkali metals, alkali earth metals, transition metals, or rare earth metals.

7 . The organic electroluminescent device as claimed in claim 4 , wherein the dopant of the doped buffer layer is selected from lithium (Li), cesium (Cs), strontium (Sr), or samarium (Sm).

8 . The organic electroluminescent device as claimed in claim 4 , wherein a dopant concentration of the doped buffer layer is about 0.1-99% by weight.

9 . The organic electroluminescent device as claimed in claim 4 , wherein a dopant concentration of the doped buffer layer is about 0.1-30% by weight.

10 . The organic electroluminescent device as claimed in claim 1 , wherein the doped buffer layer has a thickness of about 1 nm to 50 nm.

11 . The organic electroluminescent device as claimed in claim 1 , wherein the thin metal layer has a thickness of about 1 nm to 20 nm.

12 . The organic electroluminescent device as claimed in claim 1 , wherein the thin metal layer comprises aluminum (Al), silver (Ag), barium (Ba), calcium (Ca), magnesium (Mg)/Ag alloy, Al/Li alloy, or Al/Ba alloy.

13 . The organic electroluminescent device as claimed in claim 1 , wherein the transparent electrode has a thickness of about 10 nm to 400 nm.

14 . The organic electroluminescent device as claimed in claim 1 , wherein the transparent electrode comprises indium tin oxide (ITO) or indium zinc oxide (IZO).

15 . The organic electroluminescent device as claimed in claim 1 , wherein the organic electroluminescent material layer comprises:

a hole injection layer (HIL) on the anode;

a hole transporting layer (HTL) on the hole injection layer;

an emitting layer (EML) on the hole transporting layer;

an electron transporting layer (ETL) on the emitting layer; and

an electron injection layer (EIL) on the electron transporting layer.

16 . The organic electroluminescent device as claimed in claim 1 , wherein the organic electroluminescent device is a top emission device or a dual emission device.

17 . The organic electroluminescent device as claimed in claim 1 , wherein the substrate comprises glass, plastic foil or metal foil.

18 . The organic electroluminescent device as claimed in claim 1 , wherein the anode comprises ITO, IZO, aurum (Au), or platinum (Pt).

19 . An organic electroluminescent display, comprising:

a display area comprising an organic electroluminescent device as claimed in claim 1;

a scan line driver and a data line driver coupled to the display area; and

a control circuit controlling the scan line driver and the data line driver to render images.

20 . An electronic device, comprising:

an organic electroluminescent display as claimed in claim 19; and

a input device providing image data to the organic electroluminescent display to render images.