Electroluminescent efficiency

• US 20060008673A1
• Filed: 12/21/2004
• Published: 01/12/2006
• Est. Priority Date: 07/07/2004
• Status: Active Grant

• Current Assignee: University of Southern California
• Original Assignee: University of Southern California
• Inventors: Knowles, David, Li, Xiao-Chang Charles, Ma, Bin, Kwong, Raymond, Ceyrolles, William
• Granted Patent: US 7,709,100 B2
• Time in Patent Office: Days
• US Class Current: 428/690
• CPC Class Codes: C07F 15/0033 Iridium compounds
• CPC Class Codes: C07F 15/006 Palladium compounds
• CPC Class Codes: C07F 15/0073 Rhodium compounds
• CPC Class Codes: C07F 15/0086 Platinum compounds
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1011 Condensed systems
• CPC Class Codes: C09K 2211/1029 containing one nitrogen atom as the heteroatom
• CPC Class Codes: C09K 2211/1088 containing oxygen as the only heteroatom
• CPC Class Codes: C09K 2211/1092 containing sulfur as the only heteroatom
• CPC Class Codes: C09K 2211/185 of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd
• 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 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

An organic light emitting device is provided. The device has an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer further includes a molecule of Formula I wherein an alkyl substituent at position R′₅ results in high efficiency and operational stability in the organic light emitting device.

Claims

1. A compound having the formula:

2. The compound of claim 1 wherein m=3

3. The compound of claim 1 having the formula

4. The compound of claim 3 having the formula:

5. The compound of claim 1 wherein at least one of R′

₃, R′

₄, and R′

₆ is not H.

6. The compound of claim 5 having the structure

7. The compound of claim 5 wherein at least one of R′

₃, R′

₄, and R′

₆ is alkyl or phenyl.

8. The compound of claim 5 wherein R₅ has the formula

9. The compound of claim 1 wherein R′

₃, R′

₄, R′

₆, R₃, R₄, R₅ and R₆ are all H.

10. The compound of claim 9 having the formula

11. The compound of claim 1 having the formula:

12. A device comprising

an anode;

a cathode;

an organic layer including an emissive material disposed between the anode and the cathode, the emissive material comprising a compound as set forth in claim 1 such that, when a voltage is applied between the anode and the cathode, the device produces phosphorescent emission and has an unmodified external quantum efficiency of at least about 10% at current densities between about 0.1 and about 1000 mA/cm².

13. The device of claim 12, wherein the device has an unmodified external quantum efficiency of at least about 15% at current densities between about 0.1 and about 1000 mA/cm².

14. The device of claim 12 further comprising 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 non-heterocyclic aromatic hydrocarbon material.

15. The device of claim 14 wherein the device has an unmodified external quantum efficiency of at least about 15% at current densities between about 0.1 to about 1000 mA/cm².

16. The device of claim 12 wherein the device has an unmodified external quantum efficiency of at least about 20% at current densities between about 0.1 to about 1000 mA/cm².

17. The device of claim 14, wherein the aromatic hydrocarbon material has a molecular dipole moment less than about 2.0 debyes.

18. The device of claim 12, wherein the device has a T_(0.5)-L₀ product that is at least 3×

10⁶ nit-hours.

19. The device of claim 12, wherein the emissive material has the structure:

20. An organic light emitting device comprising

an anode

a cathode, and

an emissive layer disposed between the anode and the cathode

wherein the emissive layer comprises an emissive material wherein the emissive layer comprises an emissive material having the formula:

wherein

M is a metal selected from Ir, Pt, Rh or Pd;

(X-Y) is an ancillary ligand;

m is a value from 1 to the maximum number of ligands that may be attached to the metal; and

m+n is the maximum number of ligands that may be attached to the metal;

ring A is an aromatic heterocyclic or a fused aromatic heterocyclic ring having an alkyl substituent at the R′

₅ position and having at least one nitrogen atom, N, that is coordinated to the metal M,

wherein the ring A can be optionally substituted with one or more substituents at the R′

₃, R′

₄ and R′

₆ positions;

R′

₃ R′

₄ and R′

₆ are each independently H, alkyl, alkenyl, alkynyl, heteroalkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, aralkyl; and

wherein R′

₃ R′

₄ and R′

₆ are optionally substituted by one or more substituents Z;

additionally or alternatively the R′

₃ and R′

₄ substituted positions on ring A together form, independently a fused ring, wherein the fused ring may be optionally substituted;

ring B is an aromatic ring with at least one carbon atom coordinated to metal M, wherein ring B can be optionally substituted with one or more substituents at the R₃, R₄, R₅ and R₆ positions;

R₃, R₄, R₅ and R₆ is each independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, alkylaryl, CN, CO₂R, C(O)R, NR₂, OR, halo, aryl, heteroaryl, substituted aryl, substituted heteroaryl or a heterocyclic group such that when R₁₃, R′

₄, and R′

₆ are all H, R₃, R₄, R₅ and R₆ are also all H or at least one of R₄, R₅ and R₆ is selected from the group consisting of a linking group covalently linking two or more of the maximum number of ligands that may be attached to the metal, an unsubstituted phenyl ring, a fluoro-substituted phenyl ring, and a phenyl ring substituted with a substituent that renders the phenyl ring equally or less coplanar than the unsubstituted phenyl ring with respect to Ring B;

alternatively, R′

₃ and R₆ may be bridged by a group selected from —

CR₂—

CR₂—

, —

CR═

CR—

, —

CR₂—

, —

O—

, —

NR—

, —

O—

CR₂—

, —

NR—

CR₂—

, and —

N═

CR—

;

each R is independently H, alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, or aralkyl;

wherein R is optionally substituted by one or more substituents Z;

each Z is independently a halogen, R′

, O R′

, N(R′

)₂, S R′

, C(O)R′

, C(O)O R′

, C(O)N(R′

)₂, CN, SO₂, SO R′

, SO₂ R′

, or SO₃ R′

and

each R′

is independently H, alkyl, alkenyl, alkynyl, heteroalkyl, aryl, or heteroaryl.