Organic light emitting diode and display device including the same

1. An organic light emitting diode, comprising:

a first electrode layer disposed on a base substrate;

a second electrode layer disposed on the first electrode layer and facing the first electrode layer;

an emitting layer disposed between the first electrode layer and the second electrode layer;

a hole transport region disposed between the emitting layer and the first electrode layer;

an auxiliary layer disposed between the hole transport region and the emitting layer, the auxiliary layer comprising a first material and a second material; and

an electron transport region disposed between the emitting layer and the second electrode layer,

wherein:

a lowest unoccupied molecular orbital (LUMO) energy level of the first material is higher than a LUMO energy level of the emitting layer;

a LUMO energy level of the second material is lower than the LUMO energy level of the emitting layer; and

a highest occupied molecular orbital (HOMO) energy level of the first material is higher than a HOMO energy level of the second material.

2. The organic light emitting diode of claim 1 , wherein:

the emitting layer comprises a host material and a dopant material;

the LUMO energy level of the first material is higher than a LUMO energy level of the host material; and

the LUMO energy level of the second material is lower than the LUMO energy level of the host material.

3. The organic light emitting diode of claim 2 , wherein:

the emitting layer further comprises a third material; and

the third material is the same as the second material.

4. The organic light emitting diode of claim 3 , wherein an energy band gap of the third material is larger than an energy band gap of the dopant material.

5. The organic light emitting diode of claim 2 , wherein the auxiliary layer comprises:

a first layer comprising the first material; and

a second layer comprising the first and second materials,

wherein the first layer is disposed between the second layer and the emitting layer, and the second layer is disposed between the first layer and the hole transport region.

6. The organic light emitting diode of claim 5 , wherein the auxiliary layer further comprises a third layer comprising the first material disposed between the second layer and the hole transport region.

7. The organic light emitting diode of claim 2 , wherein the HOMO energy level of the first material and the HOMO energy level of the second material are each higher than a HOMO energy level of the host material.

8. The organic light emitting diode of claim 1 , wherein:

the auxiliary layer has a thickness proportional to a wavelength of light emitted from the emitting layer; and

a resonance distance between the first and second electrodes is adjusted by the thickness of the auxiliary layer.

9. A display device, comprising:

a base substrate; and

pixels disposed on the base substrate, each of the pixels comprising an organic light emitting diode,

wherein the organic light emitting diode comprises:

a first electrode layer disposed on the base substrate;

a second electrode layer disposed on the first electrode layer and facing the first electrode layer;

an emitting layer disposed between the first and second electrode layers;

a hole transport region disposed between the emitting layer and the first electrode layer;

an electron transport region disposed between the emitting layer and the second electrode layer; and

an auxiliary layer disposed between the hole transport region and the emitting layer, the auxiliary layer comprising:

a first material having a lowest unoccupied molecular orbital (LUMO) energy level higher than a LUMO energy level of the emitting layer, the first material being configured to prevent electrons from moving the emitting layer to the hole transport region; and

a second material having a LUMO energy level lower than the LUMO energy level of the emitting layer, and

wherein a highest occupied molecular orbital (HOMO) energy level of the first material is higher than a HOMO energy level of the second material.

10. The display device of claim 9 , wherein:

the emitting layer comprises a host material and a dopant material;

the LUMO energy level of the first material is higher than a LUMO energy level of the host material; and

the LUMO energy level of the second material is lower than the LUMO energy level of the host material.

11. The display device of claim 10 , wherein:

the emitting layer further comprises a third material;

the third material is the same as the second material; and

an energy band gap of the third material is lager than an energy band gap of the dopant material.

12. The display device of claim 10 , wherein the auxiliary layer comprises:

a first layer comprising the first material; and

a second layer comprising the first and second materials,

wherein the first layer is disposed between the second layer and the emitting layer, and the second layer is disposed between the first layer and the hole transport region.

13. The display device of claim 12 , wherein the auxiliary layer further comprises a third layer comprising the first material disposed between the second layer and the hole transport region.

14. The display device of claim 10 , wherein the HOMO energy level of the first material and the HOMO energy level of the second material are each higher than a HOMO energy level of the host material.

15. The display device of claim 10 , wherein:

the emitting layer comprises a first emitting layer emitting light having a first wavelength and a second emitting layer emitting light having a second wavelength shorter than the first wavelength; and

when the auxiliary layer comprises a first auxiliary layer disposed between the first emitting layer and the hole transport region, and a second auxiliary layer disposed between the second emitting layer and the hole transport region, the first auxiliary layer is thicker than the second auxiliary layer.

16. A method of manufacturing an organic light emitting diode, the method comprising:

forming a first electrode layer on a base substrate;

forming a hole transport region on the first electrode layer;

forming an auxiliary layer comprising a first material and a second material on the hole transport region;

forming an emitting layer on the auxiliary layer;

forming an electron transport region on the emitting layer; and

forming a second electrode layer on the electron transport region,

wherein:

a lowest unoccupied molecular orbital (LUMO) energy level of the first material is higher than a LUMO energy level of the emitting layer;

a LUMO energy level of the second material is lower than the LUMO energy level of the emitting layer; and

a highest occupied molecular orbital (HOMO) energy level of the first material is higher than a HOMO energy level of the second material.

17. The method of claim 16 , wherein forming the auxiliary layer comprises:

forming a first layer comprising the first material between the emitting layer and the hole transport region; and

forming a second layer comprising the first and second materials between the first layer and the hole transport region.

18. The method of claim 16 , wherein each of the HOMO energy level of the first material and the HOMO energy level of the second material is higher than a HOMO energy level of a host material of the emitting layer.