Organometallic compounds and emission-shifting organic electrophosphorescence

• US 20020182441A1
• Filed: 10/16/2001
• Published: 12/05/2002
• Est. Priority Date: 08/11/2000
• Status: Active Grant

• Current Assignee: The Trustees of Princeton University (Princeton University), University of Southern California
• Original Assignee: The Trustees of Princeton University (Princeton University)
• Inventors: Baldo, Marc A., Forrest, Stephen R., Lamansky, Sergey, Thompson, Mark E., Kwong, Raymond, Adachi, Chihaya, Adamovich, Vadim, Djurovich, Peter I.
• Granted Patent: US 6,939,624 B2
• Time in Patent Office: Days
• US Class Current: 428/690
• CPC Class Codes: C07F 15/0033 Iridium compounds
• CPC Class Codes: C07F 15/0086 Platinum compounds
• 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: C09K 2211/1014 bridged by heteroatoms, e.g. N, P, Si or B
• CPC Class Codes: C09K 2211/1029 containing one nitrogen atom as the heteroatom
• CPC Class Codes: C09K 2211/1044 containing two nitrogen atoms as heteroatoms
• 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 85/341 Transition metal complexes, e.g. Ru(II)polypyridine complexes H10K85/331 takes precedence
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/346 comprising platinum
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

Emissive phosphorescent organometallic compounds are described that produce improved electroluminescence, particularly in the blue region of the visible spectrum. Organic light emitting devices employing such emissive phosphorescent organometallic compounds are also described. Also described is an organic light emitting layer including a host material having a lowest triplet excited state having a decay rate of less than about 1 per second; a guest material dispersed in the host material, the guest material having a lowest triplet excited state having a radiative decay rate of greater than about 1×10⁵ or about 1×10⁶ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the guest material.

Claims

1. An organic light emitting device including an emissive layer comprising an organometallic compound comprised of:

a heavy transition metal that produces an efficient phosphorescent emission at room temperature from a mixture of metal-to-ligand charge transfer and π

-π

* ligand states;

at least one mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the at least one mono-anionic, bidentate, carbon-coordination ligand is substituted with at least one of an electron donating substituent and an electron withdrawing substituent, wherein the at least one of an electron donating substituent and an electron withdrawing substituent shifts the emission, relative to an un-substituted mono-anionic, bidentate, carbon-coordination ligand, to either the blue, green or red region of the visible spectrum; and

at least one non-mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the at least one non-mono-anionic, bidentate, carbon-coordination ligand causes the emission to have a well defined vibronic structure.

2. The organic light emitting device of claim 1, wherein the heavy transition metal is selected from the group consisting of Os, Ir, Pt and Au.

5. The organic light emitting device of claim 1, wherein the at least one mono-anionic, bidentate, carbon-coordination ligand is selected from the group consisting of:

6. The organic light emitting device of claim 1, wherein the at least one mono-anionic, bidentate, carbon-coordination ligand is selected from the group consisting of:

7. The organic light emitting device of claim 1, wherein the at least one non-mono-anionic, bidentate, carbon-coordination ligand is selected from the group consisting of:

8. The organic light emitting device of claim 1, wherein the at least one non-mono-anionic, bidentate, carbon-coordination ligand is selected from the group consisting of:

10. The organic light emitting device of claim 1, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

11. The organic light emitting device of claim 2, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

14. The organic light emitting device of claim 5, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

15. The organic light emitting device of claim 6, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

16. The organic light emitting device of claim 7, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

17. The organic light emitting device of claim 8, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

19. The organic light emitting device of claim 10, wherein the energy difference between the lowest triplet excited state of the organometallic compound and a corresponding relaxed stated of the organometallic compound has a corresponding wavelength of about 420 nm to 480 nm for blue light emission.

20. The organic light emitting device of claim 10, wherein the energy difference between the lowest triplet excited state of the organometallic compound and a corresponding relaxed stated of the organometallic compound has a corresponding wavelength of about 480 nm to 510 nm for aqua-blue light emission.

21. The organic light emitting device of claim 10, wherein the host material has a bandgap with an energy difference corresponding to about 470 nm and the organometallic compound has a lowest triplet excited state at an energy level at about 450 nm.

22. The organic light emitting device of claim 10, wherein the host material is an electron transport layer.

23. The organic light emitting device of claim 10, wherein the host material conducts electrons primarily through hole transmission.

24. The organic light emitting device of claim 10, wherein the ratio of the host material and organometallic compound decay rates is at least about 1:

1000 to about 5;

1000.

25. The organic light emitting device of claim 10, wherein the host material is TPD.

26. The organic light emitting device of claim 10, wherein a plurality of organometallic compounds are dispersed in the host material.

28. The organometallic compound of claim 27, wherein the heavy transition metal is selected from the group consisting of Os, Ir, Pt and Au.

3. An organic light emitting device including an emissive layer comprising an organometallic compound comprised of:

a heavy transition metal;

at least one mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal; and

at least one non-mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the organometallic compound has a chemical structure represented by a formula selected from the group consisting of;

12. The organic light emitting device of claim 3, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

4. An organic light emitting device including an emissive layer comprising an organometallic compound comprised of:

a heavy transition metal;

at least one mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal; and

at least one non-mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the organometallic compound has a chemical structure represented by the following formula;

13. The organic light emitting device of claim 4, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

9. An organic light emitting device including an emissive layer comprising an organometallic compound comprised of:

a heavy transition metal selected from the group consisting of Os, Ir, Pt and Au;

at least one mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the at least one mono-anionic, bidentate, carbon-coordination ligand is selected from the group consisting of;

wherein X=S, O, NR; and

R₁, R₂, R₃, R₄ and R₅ are, independently, hydrogen, halogen, alkyl, aryl or arylene; and

R′

₁, and R′

₂ may, in combination, be aryl; and

at least one non-mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the at least one non-mono-anionic, bidentate, carbon-coordination ligand is selected from the group consisting of;

wherein R, R₁, R₂, R₃, R₄, R₅, R₆, R₇ and R₈ are, independently, hydrogen, halogen, alkyl or aryl.

18. The organic light emitting device of claim 9, wherein the emissive layer further comprises:

a host material having a lowest triplet excited state having a first decay rate of less than about 1 per second;

wherein the organometallic compound is present as a guest material dispersed in the host material, the organometallic compound having a lowest triplet excited state having a radiative decay rate of greater than about 1×

10⁵ per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the organometallic compound.

27. An organometallic compound comprising:

a heavy transition metal that produces an efficient phosphorescent emission at room temperature from a mixture of metal-to-ligand charge transfer and π

-π

* ligand states;

at least one mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the at least one mono-anionic, bidentate, carbon-coordination ligand is substituted with at least one of an electron donating substituent and an electron withdrawing substituent, wherein the at least one of an electron donating substituent and an electron withdrawing substituent shifts the emission, relative to an un-substituted mono-anionic, bidentate, carbon-coordination ligand, to either the blue, green or red region of the visible spectrum; and

at least one non-mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the at least one non-mono-anionic, bidentate, carbon-coordination ligand causes the emission to have a well defined vibronic structure.

29. An organometallic compound comprising:

a heavy transition metal;

at least one mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal; and

at least one non-mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the organometallic compound has a chemical structure represented by a formula selected form the group consisting of;

30. An organometallic compound comprising:

a heavy transition metal;

at least one mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal; and

at least one non-mono-anionic, bidentate, carbon-coordination ligand bound to the heavy transition metal, wherein the organometallic compound has a chemical structure represented by the following formula;