ORGANIC ELECTROLUMINESCENCE ELEMENT

• US 20090026939A1
• Filed: 07/23/2008
• Published: 01/29/2009
• Est. Priority Date: 07/27/2007
• Status: Active Grant

• Current Assignee: UDC Ireland Limited
• Original Assignee: UDC Ireland Limited
• Inventors: Kinoshita, Masaru, Tobise, Manabu
• Granted Patent: US 8,129,897 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2101/80 Composition varying spatially, e.g. having a spatial gradient
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/346 comprising platinum
• 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

Abstract

The present invention provides an organic electroluminescence element having at least a light-emitting layer disposed between a pair of electrodes, wherein the light-emitting layer includes at least two electron transporting materials and a hole transporting host material, with at least one of the electron transporting materials being an electron transporting light-emitting material, and a total concentration of the at least two electron transporting materials in the light-emitting layer decreases from a cathode side toward an anode side.

Claims

1. An organic electroluminescence element comprising at least a light-emitting layer disposed between a pair of electrodes, wherein the light-emitting layer comprises at least two electron transporting materials and a hole transporting host material, with at least one of the electron transporting materials being an electron transporting light-emitting material, and a total concentration of the at least two electron transporting materials in the light-emitting layer decreases from a cathode side toward an anode side.

2. The organic electroluminescence element according to claim 1, wherein the at least two electron transporting materials comprise the electron transporting light-emitting material and an electron transporting host material, and a ratio of a total concentration of the electron transporting light-emitting material and the electron transporting host material in an interface region of the light-emitting layer on the anode side with respect to a total concentration of the electron transporting light-emitting material and the electron transporting host material in an interface region of the light-emitting layer on the cathode side (total concentration of electron transporting light-emitting material and electron transporting host material in interface region of light-emitting layer on anode side/total concentration of electron transporting light-emitting material and electron transporting host material in interface region of light-emitting layer on cathode side) is from 0% to 50%.

3. The organic electroluminescence element according to claim 2, wherein the total concentration of the electron transporting light-emitting material and the electron transporting host material is 30% by weight or less in the interface region of the light-emitting layer on the anode side.

4. The organic electroluminescence element according to claim 2, wherein the total concentration of the electron transporting light-emitting material and the electron transporting host material is 30% by weight or more in the interface region of the light-emitting layer on the cathode side.

5. The organic electroluminescence element according to claim 1, wherein the electron transporting light-emitting material is a phosphorescent light-emitting material.

6. The organic electroluminescence element according to claim 5, wherein the phosphorescent light-emitting material is a metal complex having a tri- or higher-dentate ligand.

7. The organic electroluminescence element according to claim 1, wherein the hole transporting host material is a carbazole derivative or an indole derivative.

8. The organic electroluminescence element according to claim 7, wherein the hole transporting host material is 1,3-bis(carbazole-9-yl)benzene or a derivative thereof.

9. The organic electroluminescence element according to claim 2, wherein the electron transporting host material is an azole derivative or an azine derivative.

10. The organic electroluminescence element according to claim 1, wherein a peak wavelength of an emission spectrum is 430 nm or more, and less than 480 nm.