Organometallic complexes as phosphorescent emitters in organic LEDs

• US 20020034656A1
• Filed: 06/18/2001
• Published: 03/21/2002
• Est. Priority Date: 09/14/1998
• Status: Active Grant

• Current Assignee: The Trustees of Princeton University (Princeton University), University of Southern California
• Original Assignee: University of Southern California
• Inventors: Burrows, Paul E., Baldo, Marc A., Forrest, Stephen R., Abdel-Razzaq, Feras, Lamansky, Sergey, Thompson, Mark E., Kwong, Raymond, Djurovich, Peter, Murphy, Drew
• Granted Patent: US 6,830,828 B2
• Time in Patent Office: Days
• US Class Current: 428/690
• CPC Class Codes: C07D 209/86 with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to carbon atoms of the ring system
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1007 Non-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 2211/1033 with oxygen
• CPC Class Codes: C09K 2211/1037 with sulfur
• 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: C09K 2211/186 of the light metals other than alkali metals and alkaline earth metals, i.e. Be, Al or Mg
• 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 50/18 Carrier blocking layers
• CPC Class Codes: H10K 85/146 poly N-vinylcarbazol; Derivatives thereof
• CPC Class Codes: H10K 85/30 Coordination compounds
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/346 comprising platinum
• CPC Class Codes: H10K 85/348 : comprising osmium
• CPC Class Codes: H10K 85/631 : Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
• CPC Class Codes: H10K 85/633 : comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom
• CPC Class Codes: H10K 85/649 : Aromatic compounds comprising a hetero atom
• CPC Class Codes: H10K 85/653 : comprising only oxygen as heteroatom
• CPC Class Codes: H10K 85/654 : comprising only nitrogen as heteroatom H10K85/652 takes precedence
• CPC Class Codes: H10K 85/655 : comprising only sulfur as heteroatom
• CPC Class Codes: H10K 85/657 : Polycyclic condensed heteroaromatic hydrocarbons
• CPC Class Codes: H10K 85/6572 : comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole
• CPC Class Codes: Y10S 428/917 : Electroluminescent

Abstract

Organic light emitting devices are described wherein the emissive layer comprises a host material containing an emissive molecule, which molecule is adapted to luminesce when a voltage is applied across the heterostructure, and the emissive molecule is selected from the group of phosphorescent organometallic complexes, including cyclometallated platinum, iridium and osmium complexes. The organic light emitting devices optionally contain an exciton blocking layer. Furthermore, improved electroluminescent efficiency in organic light emitting devices is obtained with an emitter layer comprising organometallic complexes of transition metals of formula L₂MX, wherein L and X are distinct bidentate ligands. Compounds of this formula can be synthesized more facilely than in previous approaches and synthetic options allow insertion of fluorescent molecules into a phosphorescent complex, ligands to fine tune the color of emission, and ligands to trap carriers.

Claims

1. An emissive layer of an organic light emitting device comprising a phosphorescent organometallic compound for enhancing the quantum efficiency of the organic light emitting device.

2. An emissive layer of an organic light emitting device comprising a phosphorescent organometallic compound for enhancing the quantum efficiency of the organic light emitting device, wherein the phosphorescent organometallic compound is selected from the group consisting of iridium and osmium compounds.

3. The emissive layer of claim 2 wherein the phosphorescent organometallic compound is an osmium compound.

4. The emissive layer of claim 3 further comprising a host material for the osmium compound.

5. The emissive layer of claim 4 wherein the osmium compound is denoted by the formula:

6. The emissive layer of claim 4 wherein the emissive layer is one layer of an organic light emitting device, including at least an anode and a cathode, and wherein the emissive layer produces light when a voltage is applied across the anode and the cathode of the organic light emitting device.

7. The emissive layer of claim 4 wherein the host material is a hole-transporting material selected from the group consisting of substituted tri-aryl amines and polyvinylcarbazoles.

8. The emissive layer of claim 7 wherein the hole transporting material comprises 4,4′

-N,N′

-dicarbazole-biphenyl as denoted by the formula;

9. The emissive layer of claim 4 wherein the host material is a hole-transporting material and the hole transporting material further comprises 4,4′

-bis[N-(1-naphthyl)-N-phenyl-amino] biphenyl.

10. The emissive layer of claim 4 wherein the host material is an electron transporting material.

11. The emissive layer of claim 10 wherein the electron transporting material comprises tris-(8-hydroxyquinoline) aluminum.

12. The emissive layer of claim 3 further comprising a polarization dopant having a dipole moment.

13. The emissive layer of claim 3 wherein the emissive layer is in contact with an exciton blocking layer.

14. The emissive layer of claim 13 wherein the exciton blocking layer comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline as denoted by the formula:

15. The emissive layer of claim 2 wherein the phosphorescent organometallic compound is an iridium compound.

16. The emissive layer of claim 15 further comprising a host material for the organometallic iridium compound.

17. The emissive layer of claim 16 wherein the iridium compound produces a green emission when a voltage is applied across the emissive layer.

18. The emissive layer of claim 16 wherein the iridium compound is fac-tris(2-phenylpyridine) iridium, as denoted by the formula:

19. The emissive layer of claim 16 wherein the emissive layer is one layer of an organic light emitting device including at least an anode and a cathode, and wherein the emissive layer produces light when a voltage is applied across the anode and the cathode of the organic light emitting device.

20. The emissive layer of claim 16 wherein the host material is a hole-transporting material selected from the group consisting of substituted tri-aryl amines and polyvinylcarbazoles.

21. The emissive layer of claim 20 wherein the hole transporting material comprises 4,4′

-N,N′

-dicarbazole-biphenyl as denoted by the formula;

22. The emissive layer of claim 20 wherein the host material is a hole-transporting material and the hole transporting material further comprises 4,4′

-bis [N-(1-naphthyl)-N-phenyl-amino] biphenyl.

23. The emissive layer of claim 16 wherein the host material is an electron transporting material.

24. The emissive layer of claim 23 wherein the electron transporting material comprises tris-(8-hydroxyquinoline) aluminum.

25. The emissive layer of claim 16 further comprising a polarization dopant having a dipole moment.

26. The emissive layer of claim 16 wherein the emissive layer is in contact with an exciton blocking layer.

27. The emissive layer of claim 26 wherein the exciton blocking layer comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline as denoted by the formula:

30. The organic light emitting device of claim 29 wherein the phosphorescent organometallic compound is an iridium compound, and wherein the emissive layer further comprises a host material for the iridium compound.

31. The organic light emitting device of claim 30 wherein the iridium compound is fac-tris(2-phenylpyridine) iridium, as denoted by the formula:

32. The organic light emitting device of claim 30 wherein the iridium compound produces a green emission when a voltage is applied across the emissive layer.

33. The organic light emitting device of claim 29 wherein the phosphorescent organometallic compound is an osmium compound, and wherein the emissive layer further comprises a host material for the osmium compound.

34. The organic light emitting device of claim 33 wherein the osmium compound is denoted by the formula:

35. The organic light emitting device of claim 34 wherein the host material is a hole-transporting material selected from the group of hole-transporting materials consisting of substituted tri-aryl amines and polyvinylcarbozoles.

36. The organic light emitting device of claim 35 wherein the hole transporting material comprises 4,4′

-N,N′

-dicarbazole-biphenyl as denoted by the formula;

37. The organic light emitting device of claim 30 wherein the host material is an electron transporting material.

38. The organic light emitting device of claim 37 wherein the electron transporting material comprises tris-(8-hydroxyquinoline) aluminum.

39. The organic light emitting device of claim 30 wherein the emissive layer further comprises a polarization dopant having a dipole moment.

40. The organic light emitting device of claim 30 wherein the emissive layer is in contact with an exciton blocking layer.

41. The organic light emitting device of claim 40 wherein the exciton blocking layer comprises 2,9-dimethyl-1,10-phenanthroline as denoted by the formula:

42. The organic light emitting device of claim 33 wherein the host material is a hole-transporting material selected from the group of hole-transporting materials consisting of substituted tri-aryl amines and polyvinylcarbozoles.

43. The organic light emitting device of claim 42 wherein the hole transporting material comprises 4,4′

-N,N′

-dicarbazole-biphenyl as denoted by the formula;

44. The organic light emitting device of claim 42 wherein the hole transporting material further comprises 4,4′

-bis[N-(1-naphthyl)-N-phenyl-amino] biphenyl.

45. The organic light emitting device of claim 33 wherein the host material is an electron transporting material.

46. The organic light emitting device of claim 45 wherein the electron transporting material comprises tris-(8-hydroxyquinoline) aluminum.

47. The organic light emitting device of claim 33 wherein the emissive layer further comprises a polarization dopant having a dipole moment.

48. The organic light emitting device of claim 33 wherein the emissive layer is in contact with an exciton blocking layer.

49. The organic light emitting device of claim 48 wherein the exciton blocking layer comprises 2,9-dimethyl-1,10-phenanthroline as denoted by the formula:

50. A display device incorporating at least one of the organic light emitting device of claim 29.

51. The display device of claim 50 wherein the display device is incorporated into a system selected from the group of systems consisting of a vehicle, a computer, a television, a printer, a flush-mounted wall monitor, a billboard, a stadium screen, a theater screen, and a sign.

66. The organic light emitting device of claim 28 wherein the at least one emissive layer further comprises a host material, wherein the phosphorescent organometallic compound is present as a dopant in said host material.

67. A display device incorporating at least one of the organic light emitting device of claim 66.

68. The display device of claim 67 wherein the display device is incorporated into a system selected from the group of systems consisting of a vehicle, a computer, a television, a printer, a flush-mounted wall monitor, a billboard, a stadium screen, a theater screen, and a sign.

71. The device of claim 69 wherein L is selected from the group consisting of 2-((1-naphthyl)benzoxazole), (2-phenylbenzoxazole), (2-phenylbenzothiazole), (7,8-benzoquinoline), coumarin, (thienylpyridine), phenylpyridine, benzothienylpyridine, 3-methoxy-2-phenylpyridine, thienylpyridine, and tolylpyridine;

and X is selected from the group consisting of acetylacetonate (“

acac”

), hexafluoroacetylacetonate, salicylidene, picolinate, and 8-hydroxyquinolinate.

72. The device of claim 69 wherein M is iridium.

73. The device of claim 71 wherein M is iridium.

74. The device of claim 69 wherein L is fluorescent and L₂MX is phosphorescent.

77. The device of claim 69 wherein M is selected from the group consisting of osmium, iridium and platinum.

78. The device of claim 69 wherein X functions to trap electrons or holes.

79. The device of claim 69 wherein L₂MX is made from L₂M(μ

-Cl)₂ML₂.

80. A display device incorporating at least one of the organic light emitting device of claim 69.

81. The display device of claim 80 wherein the display device is incorporated into a system selected from the group of systems consisting of a vehicle, a computer, a television, a printer, a flush-mounted wall monitor, a billboard, a stadium screen, a theater screen, and a sign.

28. An organic light emitting device comprising at least an anode, a cathode and at least one emissive layer, wherein the at least one emissive layer is located between the anode and the cathode, and the emissive layer comprises a phosphorescent organometallic compound for enhancing the quantum efficiency of the organic light emitting device.

29. An organic light emitting device comprising at least an anode, a cathode and at least one emissive layer, wherein the at least one emissive layer is located between the anode and the cathode, and the emissive layer comprises a phosphorescent organometallic compound for enhancing the quantum efficiency of the organic light emitting device, wherein the phosphorescent organometallic compound is selected from the group consisting of iridium and osmium compounds.

52. An emissive layer of an organic light emitting device comprising:

a phosphorescent organometallic compound for enhancing the quantum efficiency of the organic light emitting device; and

a host material, wherein the phosphorescent organometallic compound is present as a dopant in said host material.

53. An emissive layer of an organic light emitting device comprising:

a phosphorescent organometallic compound for enhancing the quantum efficiency of the organic light emitting device; and

a host material, wherein the phosphorescent organometallic compound is present as a dopant in said host material, and the phosphorescent organometallic compound is selected from the group consisting of phosphorescent organometallic platinum complexes.

62. The emissive layer of claim 53 wherein the phosphorescent organometallic platinum complex is substituted with at least one of electron donors and electron acceptors.

54. An emissive layer of an organic light emitting device comprising:

a phosphorescent organometallic compound for enhancing the quantum efficiency of the organic light emitting device; and

a host material, wherein the phosphorescent organometallic compound is present as a dopant in said host material, and the phosphorescent organometallic compound is selected from the group consisting of phosphorescent cyclometallated platinum complexes.

55. The emissive layer of claim 54 wherein the phosphorescent organometallic compound produces an emission at a wavelength between 400 nm and 700 nm.

56. The emissive layer of claim 55 wherein the emission will appear blue.

57. The emissive layer of claim 55 wherein the emission will appear green.

58. The emissive layer of claim 55 wherein the emission will appear red.

59. The emissive layer of claim 54 wherein the host material is a hole-transporting material selected from the group consisting of substituted tri-aryl amines and polyvinylcarbazoles.

60. The emissive layer of claim 54 wherein the host material is an electron-transporting material selected from the group consisting of metal quinoxolates, oxadiazoles and triazoles.

61. The emissive layer of claim 54 wherein the phosphorescent organometallic compound is selected from the group consisting of cis-Bis[2-(2-phenyl)pyridinato-N,C²]Pt (II), cis-Bis[2-(2′

-thienyl)pyridinato-N,C³Pt(II) and cis-Bis[benzo(h)quinolinato-N,C] Pt (II).

63. The emissive layer of claim 54 wherein the phosphorescent cyclometallated platinum complex is substituted with at least one of electron donors and electron acceptors.

64. The emissive layer of claim 54 further comprising a polarization molecule, present as a second dopant in said host material and having a dipole moment.

65. The emissive layer of claim 64 wherein the polarization molecule is an aromatic molecule substituted with at least one of electron donors and electron acceptors.

69. An organic light emitting device comprising:

an emitter layer comprising a molecule of the formula L₂MX, wherein L and X are inequivalent, bidentate ligands and M is a metal which forms octahedral complexes, and wherein the emitter layer produces an emission which has a maximum at a certain wavelength λ

_max.

70. An organic light emitting device comprising:

an emitter layer comprising a host and a dopant wherein the dopant comprises a molecule of the formula L₂MX, wherein L and X are inequivalent, bidentate ligands and M is a metal which forms octahedral complexes.

75. The device of claim 70 wherein the host is selected from the group consisting of:

76. An organic light emitting device comprising:

an emitter layer comprising a moiety L₂M, wherein L is a monoanionic bidentate ligand coordinated to M through an sp² carbon and a heteroatom, M is a metal which forms octahedral complexes, and the heteroatom of each L ligand is in a trans configuration.

82. An organic light emitting device comprising:

an emitter layer comprising a molecule of the formula LL′

L″

M wherein L, L′ and

L″

are inequivalent bidentate ligands, M is a metal which forms octahedral complexes, and the molecule of the formula LL′

L″

M is phosphorescent.

83. An organic light emitting device comprising:

an emitter layer comprising an L₂M moiety, wherein L is a bidentate ligand containing a nitrogen atom which coordinates to M and M is a metal which forms octahedral complexes, wherein the nitrogen atoms of the two L-M bonds are in a trans configuration to one another.

84. A composition of formula LL′

L″

M, wherein

L, L′

, and L″

are bidentate ligands which coordinate to M and M is a metal selected from the group consisting of the third row of the transition metal group of the periodic table which forms an octahedral complex with L, L′ and

L″

.

85. The composition of claim 84 wherein the composition electroluminesces via a phosphorescent mechanism.

86. The composition of claim 84 wherein L, L′

, and L″

each contain a nitrogen atom which coordinates to M and the nitrogen atoms are in a meridianal arrangement.

87. The composition of claim 84 wherein L and L′

are bidentate monoanionic ligands containing a nitrogen atom which coordinates to M, and L″

is a bidentate monoanionic ligand.

88. The composition of claim 84 wherein L and L′

are equivalent, monoanionic bidentate ligands which coordinate to M via an sp² hybridized carbon and a heteroatom, and L″

is a monoanionic bidentate ligand.

89. An organic light emitting device comprising:

an emitter layer comprising a moiety L₂M, wherein L is a monoanionic bidentate ligand coordinated to M through an sp² carbon and a heteroatom, and M is a metal which forms octahedral complexes, wherein the heteroatoms of the two L ligands are in a trans configuration.

90. A method of making a composition of the formula L₂MX, said method comprising the step of combining a bridged dimer of formula L₂M(μ

-Cl)₂ML₂ with a Bronsted acid XH to make an organometallic complex of formula L₂MX wherein L and X are monoanionic, bidentate ligands and M is a metal which forms octahedral complexes.