Materials and structures for enhancing the performance of organic light emitting devices

• US 7,018,723 B2
• Filed: 07/25/2003
• Issued: 03/28/2006
• Est. Priority Date: 07/25/2003
• Status: Active Grant

• Current Assignee: Universal Display Corporation
• Original Assignee: Universal Display Corporation, University of Southern California
• Inventors: Thompson, Mark E., Kwong, Raymond, Tung, Yeh-Jiun
• Primary Examiner(s): YAMNITZKY, MARIE ROSE
• Application Number:
  US10/626,579
• Publication Number:
  US 20050019604A1
• Time in Patent Office: 977 Days
• Field of Search: 428/690, 428/917, 313/504, 313/506
• US Class Current: 428/690
• CPC Class Codes: C07C 13/567 with a fluorene or hydrogenated fluorene ring system
• CPC Class Codes: C07C 13/66 the condensed ring system contains only four rings
• CPC Class Codes: C07C 15/24 containing two rings
• CPC Class Codes: C07C 15/38 containing four rings
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1007 Non-condensed systems
• CPC Class Codes: C09K 2211/1011 Condensed systems
• CPC Class Codes: H05B 33/14 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 Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2102/103 comprising indium oxides, e.g. ITO
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/14 Carrier transporting layers
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/60 Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• CPC Class Codes: H10K 85/615 Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

A device is provided, having an anode, a cathode, and a first organic layer disposed between the anode and the cathode. The first organic layer comprises a material that produces phosphorescent emission when a voltage is applied between the anode and the cathode. A second organic layer is disposed between the first organic layer and the cathode. The second organic layer is in direct contact with the first organic layer. The second organic layer may comprise an aromatic hydrocarbon material, comprising an aromatic hydrocarbon core optionally substituted, and wherein the substituents are the same or different, and each is selected from the group consisting of alkyl, aryl, heteroalkyl, substituted aryl, substituted heteroaryl and heterocyclic groups. The second organic layer may comprise a material having a dipole moment less than about 2.0 debyes, such that the device has an unmodified external quantum efficiency of at least about 3% and a lifetime of at least about 1000 hours at an initial luminance of about 100 to about 1000 cd/m². The second organic layer may be in direct contact with the cathode, or there may be a separate organic layer between the second organic layer and the cathode.

Claims

1. A device, comprising:

an anode;

a cathode;

a first organic layer disposed between the anode and the cathode, wherein the first organic layer comprises a material that produces phosphorescent emission when a voltage is applied between the anode and the cathode; and

a second organic layer disposed between the first organic layer and the cathode, wherein the second organic layer is in direct contact with the first organic layer, and wherein the second organic layer comprises an aromatic hydrocarbon material, having the structure

wherein;

R₁–

R₅ each represent no substitution, mono-, di-, or tri-substitution, and wherein the substituents are the same or different, and each is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroalkyl and substituted aryl.

2. The device of claim 1, wherein the aromatic hydrocarbon material has a dipole moment of less than about 2.0 debyes.

3. The device of claim 2, wherein the aromatic hydrocarbon has a dipole moment of zero.

4. The device of claim 1, wherein the aromatic hydrocarbon comprises a material having the structure:

5. The device of claim 1, wherein the second organic layer is in direct contact with the cathode.

6. The device of claim 1, further comprising a third organic layer disposed between the second organic layer and the cathode.

7. The device of claim 1, wherein the first organic layer comprises a hole transporting material, wherein the aromatic hydrocarbon material has a highest occupied molecular orbital that is not more than 0.81 eV less than the highest occupied molecular orbital of a hole transporting material in the first organic layer.

8. The device of claim 7, wherein the aromatic hydrocarbon material has a dipole moment less than about 2.0 debyes.

9. A device, comprising:

an anode;

a cathode;

a first organic layer disposed between the anode and the cathode, wherein the first organic layer comprises a hole transporting material and a material that produces phosphorescent emission when a voltage is applied between the anode and the cathode;

a second organic layer disposed between the first organic layer and the cathode, wherein the second organic layer is in direct contact with the first organic layer, and wherein the second organic layer comprises an aromatic hydrocarbon material having a highest occupied molecular orbital that is at least 0.81 eV less than the highest occupied molecular orbital of a hole transporting material in the first organic layer, wherein the aromatic hydrocarbon material has the structure

wherein;

R₁–

R₅ each represent no substitution, mono-, di-, or tri-substitution, and wherein the substituents are the same or different, and each is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroalkyl and substituted aryl.

10. The device of claim 9, wherein the aromatic hydrocarbon material has a dipole moment less than about 2.0 debyes.

11. A device, comprising:

an anode;

a cathode;

a first organic layer disposed between the anode and the cathode, wherein the first organic layer comprises a material that produces phosphorescent emission when a voltage is applied between the anode and the cathode;

a second organic layer disposed between the first organic layer and the cathode, wherein the second organic layer is in direct contact with the first organic layer, and wherein the second organic layer comprises an aromatic hydrocarbon material, and wherein the device has an unmodified external quantum efficiency of at least about 3% and a lifetime of at least about 1000 hours at an initial luminance of about 100 to about 1000 cd/m², wherein the aromatic hydrocarbon material has the structure

wherein;

R₁–

R₅ each represent no substitution, mono-, di-, or tri-substitution, and wherein the substituents are the same or different, and each is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroalkyl and substituted aryl.

12. The device of claim 11, wherein the device has an unmodified external quantum efficiency of at least about 5% and a lifetime of at least about 1000 hours at an initial luminance of about 100 to about 1000 cd/m².

13. The device of claim 11, wherein the aromatic hydrocarbon material has a dipole moment less than about 2.0 debyes.

14. The device of claim 11, wherein the aromatic hydrocarbon material has a zero dipole moment.

15. The device of claim 11, wherein the aromatic hydrocarbon material has the structure:

16. The device of claim 11, wherein after 100 hours of operation at an initial luminance of 600 cd/m² at least about 90% of initial luminance is retained.

17. The device of claim 11, wherein after 1000 hours of operation at an initial luminance of 1000 cd/m² at least about 70% of initial luminance is retained.