Organic light emitting device and method of fabricating the same

Patent metadata

Field	Value
Publication number	US-9640774-B2
Application number	US-201514819164-A
Country	US
Kind code	B2
Filing date	Aug 5, 2015
Priority date	Aug 22, 2014
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A light emitting device is discussed, and includes a first electrode; a hole transporting layer (HTL) on the first electrode; an organic light-emission layer (EML) having a red emission layer (EML) formed in a red sub pixel area Rp, a green emission layer formed in a green sub pixel area Gp, and a blue emission layer formed in a blue sub pixel area Bp; an electron transporting layer (ETL) on the red, green and blue emission layers; and a second electrode on the electron transporting layer, wherein the green emission layer includes a phosphor host material, a second phosphor host material, and a dopant material.

First claim

What is claimed is:

1. A light emitting device comprising:
a first electrode;
a hole transporting layer (HTL) on the first electrode;
an organic light-emission layer (EML) having a red emission layer (EML) formed in a red sub pixel area Rp, a green emission layer formed in a green sub pixel area Gp, and a blue emission layer formed in a blue sub pixel area Bp;
an electron transporting layer (ETL) on the red, green and blue emission layers; and
a second electrode on the electron transporting layer,
wherein the green emission layer includes a phosphor host material, a second phosphor host material, and a dopant material.

2. The light emitting device of claim 1 , wherein the phosphor host material has a pre-mixed state of a first phosphor host material and a third phosphor host material having a band gap wider than those of the first phosphor host material and the second phosphor host material.

3. The light emitting device of claim 1 , further comprising a first optical aid layer and a second optical aid layer arranged on the hole transporting layer and respectively formed to correspond to the red sub pixel area Rp and the green sub pixel area Gp.

4. The light emitting device of claim 2 , wherein a Lowest Unoccupied Molecular Orbital (LUMO) energy level of the third phosphor host material has a value between a LUMO energy level of the first phosphor host material and a LUMO energy level of the second phosphor host material.

5. The light emitting device of claim 2 , wherein a Highest Occupied Molecular Orbital (HOMO) energy level of the third phosphor host material has a value about the same as a HOMO energy level of the second phosphor material.

6. A light emitting device comprising:
a first electrode and a second electrode; and
an organic light-emission layer (EML) having a red emission layer, a green emission layer, and a blue emission layer between the first electrode and the second electrode,
wherein at least one of the red emission layer, the green emission layer, and the blue emission layer emits a baseline amount of light, and further includes a plurality of organic materials generating an exciplex state of energy in an exciplex state, the plurality of organic materials emitting additional amount of light above the baseline amount of light in the exciplex state due to energy corresponding to differences of different energy levels of different kinds of the plurality of organic materials.

7. The light emitting device of claim 6 , wherein the plurality of organic materials include a phosphor host material, a second phosphor host material, and a dopant material.

8. The light emitting device of claim 7 , wherein the phosphor host material has a pre-mixed state of a first phosphor host material and a third phosphor host material having a band gap wider than those of the first phosphor host material and the second phosphor host material.

9. The light emitting device of claim 8 , wherein a triplet energy level of the first phosphor host material and the third phosphor material, and a triplet energy level of the second phosphor host material have a difference.

10. The light emitting device of claim 9 , wherein the difference is 0.04 eV to 0.1 eV.

11. The light emitting device of claim 7 , wherein a Lowest Unoccupied Molecular Orbital (LUMO) energy level of the third phosphor host material has a value between a LUMO energy level of the first phosphor host material and a LUMO energy level of the second phosphor host material.

12. The light emitting device of claim 7 , wherein a Highest Occupied Molecular Orbital (HOMO) energy level of the third phosphor host material has a value about the same as a HOMO energy level of the second phosphor material.

13. The light emitting device of claim 6 , wherein the exciplex state is formed in the green emission layer.

14. The light emitting device of claim 13 , wherein the green emission layer has a thickness of 200 Å to 500 Å.

15. The light emitting device of claim 13 , wherein the phosphor dopant in the green emission layer is at a concentration level of 3 to 20%.

16. The light emitting device of claim 13 , wherein the green emission layer includes phosphor materials selected from TCTA (Tris(4-carbazoy-9-ylphenyl)amine), CBP (4,4′-Bis(N-carbazolyl)-1,1′-biphenyl), Balq (Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum) and PPV (poly(p phenylene vinylene)), as host materials.

17. The light emitting device of claim 13 , wherein the dopant includes Ir complex containing Ir(ppy)3 or Ir(mmapy)3.

18. A method of manufacturing a light emitting device, the method comprising:
forming an emission layer having an exciplex material by:
depositing a phosphor host material from a first deposition source onto a substrate;
depositing a second phosphor host material from a second deposition source onto the substrate; and
depositing a dopant material from a third deposition source onto the substrate, wherein the depositing of the phosphor host material, the second phosphor material and the dopant material occur simultaneously using a thermal evaporation method.

19. The method of claim 18 , wherein the phosphor host material includes a first phosphor host material and a third phosphor host material, which are formed in a pre-mixed state, and
wherein the third phosphor host material has a band gap wider than those of the first phosphor host material and the second phosphor host material.

20. An organic light emitting layer comprising:
a phosphor-based emission layer including a wide band gap material configured for exciplex generation that results in increased emission efficiency and reduced power consumption when compared to a conventional phosphor-based emission layer that lacks the wide band gap material,
wherein the phosphor-based emission layer includes a first phosphor host material, a second phosphor host material and a third phosphor host material, wherein the third phosphor host material is made of a wide band gap material.

21. The organic light emitting layer of claim 20 , wherein the third phosphor host material has a LUMO level between a LUMO level of the first phosphor host material and a LUMO level of the second phosphor host material.

22. The organic light emitting layer of claim 21 , wherein a triplet energy level T 1 of each of the first phosphor host material and the third phosphor host material have a difference 0.04 eV to 0.1 eV as compared with a triplet energy level T 1 of the second phosphor host material.

23. The organic light emitting layer of claim 20 , wherein the first phosphor host material and the third phosphor host material are pre-mixed with each other.

Assignees

• Lg Display Co Ltd

Inventors

• Lee Heui Dong
• Lee Kwang Yeon

Classifications

• H05B33/14 Primary

  characterised by the chemical or physical composition or the arrangement of the electroluminescent material {, or by the simultaneous addition of the electroluminescent material in or onto the light source} · CPC title

• H01L2251/5384

  Electricity · mapped topic

• H01L51/5004

  Electricity · mapped topic

• C09K11/06

  containing organic luminescent materials · CPC title

• H01L51/5016 Primary

  Electricity · mapped topic