Blue emitting internal junction organic electroluminescent device (I)

• US 5,151,629 A
• Filed: 08/01/1991
• Issued: 09/29/1992
• Est. Priority Date: 08/01/1991
• Status: Expired due to Term

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: VanSlyke, Steven A.
• Primary Examiner(s): Willis, Jr., Prince
• Assistant Examiner(s): Steinberg, Thomas
• Application Number:
  US07/738,776
• Time in Patent Office: 425 Days
• Field of Search: 252/301.16, 546/7, 313/504
• US Class Current: 313/504
• CPC Class Codes: C07F 5/069 without C-aluminium linkages
• CPC Class Codes: C09B 57/10 Metal complexes of organic compounds not being dyes in uncomplexed form
• 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 2102/103 comprising indium oxides, e.g. ITO
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 85/30 Coordination compounds
• CPC Class Codes: H10K 85/311 Phthalocyanine
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/361 Polynuclear complexes, i.e. complexes comprising two or more metal centers
• CPC Class Codes: H10K 85/615 Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
• CPC Class Codes: H10K 85/623 containing five rings, e.g. pentacene
• CPC Class Codes: H10K 85/624 containing six or more rings

Abstract

An internal junction organic electroluminescent device is disclosed comprised of, in sequence, an anode, an organic hole injecting and transporting zone, an organic electron injecting and transporting zone, and a cathode. The organic electron injecting and transporting zone is comprised of an electron injecting layer in contact with the cathode and, interposed between the electron injecting layer and the organic hole injecting and transporting zone, a blue emitting luminescent layer comprised of a bis(R^s -8-quinolinolato) aluminum(III)-μ-oxo-bis(R^s -8-quinolinolato)- aluminum(III), where R^s substituents are chosen to block the attachment of more than two substituted 8-quinolinolato ring nuclei to any one aluminum atom. Increased operating stability and device emission at even shorter blue wavelengths can be realized by the incorporation of a pentacarbocyclic aromatic fluorescent dye.

Claims

1. An internal junction organic electroluminescent device comprised of, in sequence, an anode, an organic hole injecting and transporting zone, an organic electron injecting and transporting zone, and a cathode,

characterized in that said organic electron injecting and transporting zone is comprised of

an electron injecting layer in contact with the cathode and,

interposed between the electron injecting layer and the organic hole injecting and transporting zone, a blue emitting luminescent layer comprised of a charge accepting compound of the formula:

space="preserve" listing-type="equation">(R.sup.s --Q).sub.2 --Al--O--Al--(Q--R.sup.s).sub.2

where

Q in each occurrence represents a substituted 8-quinolinolato ring nucleus and

R^s represents an 8-quinolinolato ring substituent chosen to block sterically the attachment of more than two substituted 8-quinolinolato ring nuclei to any one aluminum atom.

2. An internal device according to claim 1 further characterized in that R^s is a 2-position substituent of the 8-quinolinolato ring nucleus.

3. An internal junction organic electroluminescent device according to claim 2 further characterized in that R^s is an electron donating substituent.

4. An internal junction organic electroluminescent device according to claim 3 further characterized in that R^s is chosen from the group consisting of amino, oxy and hydrocarbon groups containing up to carbon atoms.

5. An internal junction organic electroluminescent device according to claim 4 further characterized in that R^s is a hydrocarbon containing from 1 to 6 carbon atoms.

6. An internal junction organic electroluminescent device according to claim 1 further characterized in that the 8-quinolinolato ring nucleus includes a 4-position ring substituent that is electron donating.

7. An internal junction organic electroluminescent device according to claim 6 further characterized in that the 4-position ring substituent is chosen from among amino, oxy and hydrocarbon groups containing up to 10 carbon atoms.

8. An internal junction organic electroluminescent device according to claim 1 further characterized in that the 8-quinolinolato ring nucleus includes in at least one of its 5,6 and 7 ring positions a substituent that is electron accepting.

9. An internal junction organic electroluminescent device according to claim 8 further characterized in that each of the 5, 6 and 7 ring position electron accepting substituents is chosen from among electron accepting cyano, halogen, and α

-haloalkyl, α

-haloalkoxy, amido, sulfonyl, carbonyl, carbonyloxy and oxycarbonyl substituents containing up to 10 carbon atoms.

10. An internal junction organic electroluminescent device according to claim 1 further characterized in that the luminescent layer additionally includes a fluorescent dye.

11. An internal junction organic electroluminescent device according to claim 10 further characterized in that the fluorescent dye is chosen to provide a favored recombination site for holes and electrons received from the charge accepting compound and is blue emitting.

12. An internal junction organic electroluminescent device according to claim 11 further characterized in that the blue emitting fluorescent dye exhibits a shorter wavelength emission peak than the charge accepting compound.

13. An internal junction organic electroluminescent device according to claim 11 further characterized in that the blue emitting fluorescent dye contains a stabilizing aromatic chromophoric unit containing at least 5 fused carbocyclic aromatic rings.

14. An internal junction organic electroluminescent device according to claim 13 further characterized in that the chromophoric unit contains from 20 to 40 ring carbon atoms.

15. An internal junction organic electroluminescent device according to claim 14 further characterized in that the fluorescent dye chromophoric unit is chosen from among those containing a perylene, benzopyrene, benzochrysene, benzonaphthacene, picene, pentaphene, pentacene, hexacene or anthanthrene nucleus.

16. An internal junction organic electroluminescent device according to claim 13 further characterized in that the fluorescent dye is present in a concentration ranging from 0.05 to 5 mole percent.

17. An internal junction organic electroluminescent device according to claim 16 further characterized in that the fluorecent dye is present in a concentration ranging from 0.2 to 3 mole percent.

18. An internal junction organic electroluminescent device according to claim 16 further characterized in that the fluorecent dye is present in a concentration ranging from 0.5 to 2 mole percent.

19. An internal junction organic electroluminescent device according to claim 1 further characterized in that the electron injecting and transporting zone and the hole injecting and transporting zone together exhibit a thickness of less than 1 μ

m.

20. An internal junction organic electroluminescent device according to claim 19 further characterized in that the organic electron injecting and transporting zone has a thickness of at least 300 Å

.

21. An internal junction organic electroluminescent device according to claim 20 further characterized in that the electron injecting layer has a thickness in the range of from 50 to 250 Å

.

22. An internal junction organic electroluminescent device according to claim 1 further characterized in that a metal oxinoid compound forms the electron injecting layer.

23. An internal junction organic electroluminescent device according to claim 22 further characterized in that the metal oxinoid compound satisfies the formula:

##STR14## where Me represents a metal,

n is an integer of from 1 to 3, and

Z represents the atoms necessary to complete an oxine nucleus.

24. An internal junction organic electroluminescent device according to claim 1 further characterized in that the blue emitting compound satisfies the formula:

##STR15## where R² represents an electron donating substituent,

R³ and R⁴ each independently represent hydrogen or an electron donating substituent, and

R⁵, R⁶ and R⁷ each independently represent hydrogen or an electron accepting substituent.

25. An internal junction organic electrluminescent device according to claim 24 further characterized in that the electron donating substituents are independently chosen from the group conssitign of --R'"'"', --OR'"'"' and --N(R")R'"'"', where R'"'"' is a hydrocarbon containing up to 6 carbon atoms and R" is hydrogen or R'"'"' and the electron accepting substituents are each independently chosen from among electron accepting cyano, halogen, and α

-haloalkyl, α

-haloalkoxy, amido, sulfonyl, carbonyl, carbonyloxy and oxycarbonyl substituents containing up to 6 carbon atoms.