Stacked Organic Light Emitting Device Having High Efficiency and High Brightness

• US 20070221912A1
• Filed: 04/07/2005
• Published: 09/27/2007
• Est. Priority Date: 04/09/2004
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Lee, Young, Noh, Jeoung, Jang, Jun, Hahm, Yun, Jeong, Dong, Jeong, Ji
• Granted Patent: US 8,951,645 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 85/6572 comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole
• CPC Class Codes: H10K 85/731 Liquid crystalline materials
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

A stacked organic light emitting device that includes an anode connected to an external power source, a cathode connected to the external power source, at least two light emitting sections aligned between the anode and the cathode, including a light emitting layer, and an internal electrode aligned between the light emitting sections. The internal electrode is a single-layered internal electrode which is made from one selected from the group consisting of a metal, alloys of the metal, and metal oxides thereof, having a work function below 4.5 eV, each light emitting section includes an organic material layer containing an organic material having an electron affinity above 4 eV, and the organic material layer is formed between the light emitting layer of the light emitting section and the electrode facing the anode connected to the external power source in two electrodes which make contact with the light emitting section.

Claims

1. A stacked organic light emitting device comprising:

an anode connected to an external power source;

a cathode connected to the external power source;

at least two light emitting sections aligned between the anode and the cathode, including a light emitting layer; and

an internal electrode aligned between the light emitting sections, wherein the internal electrode is a single-layered internal electrode which is made from one selected from the group consisting of a metal, alloys of the metal, and metal oxides thereof, having a work function below 4.5 eV,

each light emitting section includes an organic material layer containing an organic material having an electron affinity above 4 eV, and

the organic material layer is formed between the light emitting layer of the light emitting section and the electrode facing the anode connected to the external power source in two electrodes which make contact with the light emitting section.

2. The stacked organic light emitting device as claimed in claim 1, wherein the organic material having the electron affinity above 4 eV is a compound having a chemical formula as shown below.

wherein, R₁ to R₆ are one selected from the group consisting of hydrogen, halogen atom, nitrile(—

CN), nitro(—

NO₂), sulfonyl(—

SO₂R), sulfoxide(—

SOR), sulfonamide(—

SO₂NR₂), sulfonate(—

SO₃R), trifluoromethyl(—

CF₃), ester(—

COOR), amide(—

CONHR or —

CONRR′

), substituted or unsubstituted linear or branched C₁-C₁₂ alkoxy, substituted or unsubstituted linear or branched C₁-C₁₂ alkyl, substituted or unsubstituted aromatic or non-aromatic heterocyclic compound, substituted or unsubstituted aryl, substituted or unsubstituted mono-arylamine or de-arylamine, and substituted or unsubstituted aralkyl, and R and R′

are one selected from the group consisting of substituted or unsubstituted C₁-C₆₀ alkyl, substituted or unsubstituted aryl, and substituted or unsubstituted 5-7 membered heterocyclic compound.

3. The stacked organic light emitting device as claimed in claim 2, wherein R₁ to R₆ are nitrile(—

CN).

4. The stacked organic light emitting device as claimed in claim 1, wherein the organic material having the electron affinity above 4 eV is one selected from the group consisting of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, fluoride 3,4,9,10-perylenetetracarboxylicdianhydride (PTCDA), cyano PTCDA, naphthalenetetracarboxylicdianhydride (NTCDA), fluoride NTCDA and cyano NTCDA.

5. The stacked organic light emitting device as claimed in claim 1, wherein the internal electrode is made from at least one selected from the group consisting of Al (4.28 eV), Ag (4.26 eV), Zn (4.33 eV), Nb (4.3 eV), Zr (4.05 eV), Sn (4.42 eV), Ta (4.25 eV), V (4.3 eV), Hg (4.49 eV), Ga (4.2 eV), In (4.12 eV), Cd (4.22 eV), B (4.4 eV), Hf (3.9 eV), La (3.5 eV), Ti (4.3 eV), Ca (2.87 eV), Mg (3.66 eV), Li (2.9eV), Na (2.75eV), K (2.3eV), Cs, (2.14eV), and alloys thereof.

6. The stacked organic light emitting device as claimed in claim 1, wherein each of the stacked light emitting sections has a light emission spectrum of a color selected from red, green, blue, and combination thereof, so that the stacked organic light emitting device is able to emit white light.

7. The stacked organic light emitting device as claimed in claim 1, wherein the stacked organic light emitting device is able to emit a white light of a wide range due to a micro-cavity effect.

8. A display apparatus comprising a stacked organic light emitting device as claimed in claim 1,

the stacked organic light emitting device comprising:

an anode connected to an external power source;

a cathode connected to the external power source;

at least two light emitting sections aligned between the anode and the cathode, including alight emitting layer; and

an internal electrode aligned between the light emitting sections, wherein the internal electrode is a single-layered internal electrode which is made from one selected from the group consisting of a metal, alloys of the metal, and metal oxides thereof, having a work function below 4.5 eV, each light emitting section includes an organic material layer containing an organic material having an electron affinity above 4 eV, and

the organic material layer is formed between the light emitting layer of the light emitting section and the electrode facing the anode connected to the external power source in two electrodes which make contact with the light emitting section.

9. The display apparatus as claimed in claim 8, wherein the organic material having the electron affinity above 4 eV is a compound having a chemical formula as shown below.

wherein, R₁ to R₆ are one selected from the group consisting of hydrogen, halogen atom, nitrile(—

CN), nitro(—

NO₂), sulfonyl(—

SO₂R), sulfoxide(—

SOR), sulfonamide(—

SO₂NR₂), sulfonate(—

SO₃R), trifluoromethyl(—

CF₃), ester(—

COOR), amide(—

CONHR or —

CONRR′

), substituted or unsubstituted linear or branched C₁-C₁₂ alkoxy, substituted or unsubstituted linear or branched C₁-C₁₂ alkyl, substituted or unsubstituted aromatic or non-aromatic heterocyclic compound, substituted or unsubstituted aryl, substituted or unsubstituted mono-arylamine or de-arylamine, and substituted or unsubstituted aralkyl, and R and R′

are one selected from the group consisting of substituted or unsubstituted C₁-C₆₀ alkyl, substituted or unsubstituted aryl, and substituted or unsubstituted 5-7 membered heterocyclic compound.

10. The display of apparatus as claimed in claim 9, wherein R₁ to R₆ are nitrile(—

CN).

11. The display apparatus as claimed in claim 8, wherein the organic material having the electron affinity above 4 eV is one selected from the group consisting of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, fluoride 3,4,9,10-perylenetetracarboxylidianhydride (PTCDA), cyano PTCDA, naphthalenetetracarboxylicdianhydride (NTCDA), fluoride NTCDA and cyano NTCDA.

12. The display apparatus as claimed in claim 8, wherein the internal electrode is made from at least one selected from the group consisting of AL (4.28 eV), Ag (4.26 eV), Zn (4.33 eV), Nb (4.3 eV), Zr (4.05 eV), Sn (4.42 Ev), Ta (4.25 eV) V (4.3 eV), Hg (4.49 eV), Ga (4.2 eV), In (4.12 eV) Cd (4.22 eV), B (4.4 eV), Hf (3.9 eV), La (3.5 eV), Ti (4.3 eV), Ca (2.87 eV), Mg (3.66 eV), Li (2.9 eV), Na (2.75 eV), K (2.3 eV), Cs, (2.14 eV), and alloys thereof.

13. The display apparatus as claimed in claim 8, wherein each of the stacked light emitting sections has a light emission spectrum of a color selected from red, green, blue, and combination thereof, so that the stacked organic light emitting device is able to emit white light.

14. The display apparatus as claim in claim 8, wherein the stacked organic light emitting device is able to emit a white light of a wide range due to a micro-cavity effect.