Organic electroluminescent device with carrier blocking layer interposed between two emitting layers

• US 7,737,625 B2
• Filed: 03/15/2005
• Issued: 06/15/2010
• Est. Priority Date: 03/25/2004
• Status: Active Grant

• Current Assignee: Idemitsu Kosan Company Limited
• Original Assignee: Idemitsu Kosan Company Limited
• Inventors: Iwakuma, Toshihiro, Kawamura, Hisayuki, Kuma, Hitoshi, Hosokawa, Chishio, Arakane, Takashi
• Primary Examiner(s): Williams; Joseph L
• Application Number:
  US10/575,092
• Publication Number:
  US 20070090753A1
• Time in Patent Office: 1,918 Days
• Field of Search: 313504-506, 313498-512, 445 23- 25
• US Class Current: 313/504
• 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 2211/1048 with oxygen
• CPC Class Codes: C09K 2211/1096 containing other heteroatoms
• 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 2101/30 Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/60 Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• CPC Class Codes: H10K 85/615 Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
• CPC Class Codes: H10K 85/624 containing six or more rings
• 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 85/636 comprising heteroaromatic hydrocarbons as substituents on the nitrogen 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 85/6572 : comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole

Abstract

An organic electroluminescent device including in sequence an anode, a first emitting layer (5), a carrier barrier layer (6), a second emitting layer (7) and a cathode stacked; wherein the ionization potential of the carrier barrier layer (6) is more than the ionization potential of the first emitting layer (5) by 0.1 eV or more and the affinity level of the carrier barrier layer (6) is less than the affinity levels of the first emitting layer (5) and the second emitting layer (7) by 0.1 eV or more.

Claims

1. An organic electroluminescent device comprising in sequence an anode, a first emitting layer, a carrier barrier layer, a second emitting layer and a cathode stacked;

wherein the ionization potential of the carrier barrier layer is more than the ionization potential of the first emitting layer by 0.1 eV or more and the affinity level of the carrier barrier layer is less than the affinity levels of the first emitting layer and the second emitting layer by 0.1 eV or more;

provided that the carrier barrier layer which is formed of bathocuproine is excluded.

2. The organic electroluminescent device according to claim 1, wherein the ionization potential of the carrier barrier layer is more than the ionization potential of the first emitting layer by 0.2 eV or more and the affinity level of the carrier barrier layer is less than the affinity levels of the first emitting layer and the second emitting layer by 0.2 eV or more.

3. The organic electroluminescent device according to claim 1, wherein the first emitting layer comprises a first dopant for a first emission color and the second emitting layer comprises a second dopant for a second emission color.

4. The organic electroluminescent device according to claim 3, wherein at least one carrier barrier layer comprises a third dopant for a third emission color.

5. The organic electroluminescent device according to claim 4, wherein the first, second and third dopants are selected from blue, green or red.

6. The organic electroluminescent device according to claim 1, wherein the first emitting layer emits blue or red light.

7. The organic electroluminescent device according to claim 1, wherein the second emitting layer emits blue or red light.

8. The organic electroluminescent device according to claim 1, wherein one of the first emitting layer and the second emitting layer emits blue light, and another emitting layer emits red light.

9. The organic electroluminescent device according to claim 1, wherein the first emitting layer comprises a hole-transporting material and the second emitting layer comprises an electron-transporting material.

10. The organic electroluminescent device according to claim 9, wherein the hole mobility of the first emitting layer is 10⁻

5 cm²/v·

s or more and the electron mobility of the second emitting layer is 10<sup>−

6</sup> cm²/v·

s or more.

11. The organic electroluminescent device of claim 1 that emits white light.