Organic light emitting display device

1. An organic light emitting display (OLED) device comprising:

first and second electrodes facing each other on a substrate;

at least two light emitting units between the first and second electrodes; and

a charge generation layer between the at least two light emitting units, the charge generation layer including an N-type charge generation layer and a P-type charge generation layer,

wherein the N-type charge generation layer comprises at least two hosts and a dopant, and wherein the at least two hosts have different lowest unoccupied molecular orbital (LUMO) energy levels.

2. The OLED device according to claim 1 , wherein the N-type charge generation layer has a multi-layer or single-layer structure comprising first and second hosts and the dopant.

3. The OLED device according to claim 2 , wherein

a difference between the LUMO energy level of the first host and the LUMO energy level of the second host is about 0.1 eV or more, and

a difference between a highest occupied molecular orbital (HOMO) energy level of the first host and a HOMO energy level of the second host is about 0.1 eV or more.

4. The OLED device according to claim 2 , wherein a ratio of the second host to the first host in the N-type charge generation layer is about 5% to about 95% and a doping ratio of the dopant to the sum of the first and second hosts in the N-type charge generation layer is about 1% to about 8%.

5. The OLED device according to claim 2 , wherein the dopant includes an alkali metal or an alkali earth metal and has a work function of about −2.5 eV to about −3.2 eV.

6. The OLED device according to claim 2 , wherein the N-type charge generation layer has a multi-layer structure comprising:

a first N-type charge generation layer including the first host and the dopant;

a second N-type charge generation layer including the second host and the dopant; and

a third N-type charge generation layer including the first and second hosts and the dopant.

7. The OLED device according to claim 6 , wherein the first to third N-type charge generation layers each has a thickness of about 10 Å to about 500 Å.

8. The OLED device according to claim 2 , wherein the N-type charge generation layer has a multi-layer structure comprising:

a first N-type charge generation layer including the first host and the dopant; and

a second N-type charge generation layer including the second host and the dopant.

9. The OLED device according to claim 8 , wherein the first and second N-type charge generation layers each has a thickness of about 10 Å to about 500 Å.

10. An organic light emitting display (OLED) device comprising:

first and second electrodes facing each other on a substrate;

at least two light emitting units formed between the first and second electrodes; and

a charge generation layer formed between the at least two light emitting units, the charge generation layer comprising an N-type charge generation layer and a P-type charge generation layer, wherein

one of the at least two light emitting units comprises:

a hole transport layer on the first electrode;

an emission layer on the hole transport layer; and

an electron transport layer on the emission layer,

the N-type charge generation layer on the electron transport layer, the N-type charge generation layer including at least two hosts having different LUMO energy levels and a dopant, and

the electron transport layer including any one of the at least two hosts in the N-type charge generation layer.

11. The OLED device according to claim 10 , wherein the N-type charge generation layer has a multi-layer or single-layer structure comprising first and second hosts and a dopant.

12. The OLED device according to claim 11 , wherein

a difference between the LUMO energy level of the first host and the LUMO energy level of the second host is about 0.1 eV or more, and

a difference between a HOMO energy level of the first host and a HOMO energy level of the second host is about 0.1 eV or more.

13. The OLED device according to claim 11 , wherein a ratio of the second host to the first host in the N-type charge generation layer is about 5% to 95% and a doping ratio of the dopant to the sum of the first and second hosts in the N-type charge generation layer is about 1% to 8%.

14. The OLED device according to claim 11 , wherein the dopant includes an alkali metal or an alkali earth metal and has a work function of about −2.5 eV to about −3.2 eV.

15. The OLED device according to claim 11 , wherein the N-type charge generation layer has a multi-layer structure comprising:

a first N-type charge generation layer including the first host and the dopant;

a second N-type charge generation layer including the second host and the dopant; and

a third N-type charge generation layer including the first and second hosts and the dopant.

16. The OLED device according to claim 15 , wherein the first to third N-type charge generation layers each has a thickness of about 10 Å to about 500 Å.

17. The OLED device according to claim 11 , wherein the N-type charge generation layer has a multi-layer structure comprising:

a first N-type charge generation layer including the first host and the dopant; and

a second N-type charge generation layer including the second host and the dopant.

18. The OLED device according to claim 17 , wherein the first and second N-type charge generation layers each has a thickness of about 10 Å to about 500 Å.

19. The OLED device according to claim 11 , wherein the electron transport layer has a thickness of about 100 Å to about 500 Å.

20. A method for manufacturing an organic light emitting display (OLED) device, the method comprising:

forming a first electrode on a substrate;

forming a first light emitting unit on the first electrode;

forming a charge generation layer on the first light emitting unit, the charge generation layer including a first host, a second host and a dopant;

forming a second light emitting unit on the charge generation layer; and

forming a second electrode on the second light emitting unit,

wherein LUMO energy levels of the first host and the second host are different by about 0.1 eV or more, and wherein HOMO energy levels of the first host and the second host are different by about 0.1 eV or more.