Electroluminescent material

• US 6,524,727 B1
• Filed: 12/17/1999
• Issued: 02/25/2003
• Est. Priority Date: 06/17/1997
• Status: Expired due to Fees

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: South Bank University Limited
• Inventors: Kathirgamanathan, Poopathy
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): XU, LING X
• Application Number:
  US09/466,523
• Time in Patent Office: 1,166 Days
• Field of Search: 428/690, 428/704, 428/917, 313/504, 313/506, 252/301.16, 252/301.26, 257/40, 257/103
• US Class Current: 428/690
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• 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 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

Electrolumiinescent devices with a high photoluminescent efficiency comprise a transparent conductive substrate on which is a layer of an electroluminescent material. The electroluminescent material is a rare earth metal, actinde or transition metal organic complex which has a photoluminescent efficiency of greater than 25%.

Claims

1. An electroluminescent device comprising:

a transparent substrate, and a layer comprising an electroluminescent material above the substrate wherein the electroluminescent material comprises at least one complex selected from the group consisting of a rare earth metal complex, an actinide complex and a transition metal complex wherein the electroluminescent device has a photoluminescent efficiency of greater than 25%, the complex having the formula X(Y_m)_n where X is a rare earth metal, actinide or transition metal and n is the valence state of the metal, and Y_m is the same or different ligand wherein at least one Y_m is

where R is the same or different and is selected from the group consisting of hydrogen, hydrocarbyl, alkoxy, fluorine, nitrile, fluorocarbon, phenyl, substituted phenyl and a phenoxy moiety, and wherein each phenyl group has from 1 to 5 R substituents.

2. An electroluminescent material in accordance with claim 1 wherein the electroluminescent material has a photoluminescent efficiency of greater than 40%.

3. An electroluminescent device as in claim 1 wherein X is selected from the group consisting of Sm(III), Eu(II), Tb(III), Dy(III), Yb(III), Lu(III), Gd(III), Eu(III), Gd(III), U(III), U(VI)O₂ and Th(III).

4. An electroluminescent device according to claim 1 wherein a triplet state of the at least one ligand is no greater than 0.6 eV above a resonant frequency of the metal ion in said complex.

5. An electroluminescent device according to claim 1 wherein a triplet state of the at least one ligand is no greater than 0.4 eV above a resonant frequency of the metal ion in said complex.

6. An electroluminescent device according to claim 3 wherein a triplet state of the at least one ligand is no greater than 0.6 eV above a resonant frequency of the metal ion in said complex.

7. An electroluminescent device according to claim 3 wherein a triplet state of the at least one ligand is no greater than 0.4 eV above a resonant frequency of the metal ion in said complex.

8. An electroluminescent device according to claim 2 further comprising a hole transporting layer deposited on the transparent substrate and wherein the electroluminescent material is deposited on the hole transporting layer.

9. An electroluminescent device according to claim 2 wherein the layer includes a hole transporting material mixed with the electroluminescent material in a ratio of 5 to 95% of the electroluminescent material to 95 to 5% of the hole transporting material.

10. An electroluminescent device according to claim 9 wherein the hole transporting material is an aromatic amine complex.

11. An electroluminescent device according to claim 9 wherein the hole transporting material is selected from the group consisting of poly(vinylcarbazole),N,N′

diphenyl-N,N¹-bis(3-methylphenyl)-1,1¹-biphenyl-4,4¹-diamine and polyaniline.

12. An electroluminescent device according to claim 2 wherein the layer comprises an electron injecting material mixed with the electroluminescent material.

13. An electroluminescent device according to claim 12 wherein the electron injecting material is selected from the group consisting of a metal complex, oxadiazole, an oxadizole derivative, an aluminum quinolate and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4 oxadiazole.