Polymers for electroluminescent devices

• US 5,514,878 A
• Filed: 03/18/1994
• Issued: 05/07/1996
• Est. Priority Date: 03/18/1994
• Status: Expired due to Term

• Current Assignee: IPIFS Guarantee Corp.
• Original Assignee: Andrew B. Holmes, Derek R. Baigent, Donald C. Bradley, Neil C. Greenham, Peter J. Hamer, Raoul Cervini, Richard H. Friend, Stephen C. Moratti
• Inventors: Hamer, Peter J., Bradley, Donald C., Holmes, Andrew B., Moratti, Stephen C., Greenham, Neil C., Cervini, Raoul, Baigent, Derek R., Friend, Richard H.
• Primary Examiner(s): Crane, Sara W.
• Application Number:
  US08/210,327
• Time in Patent Office: 781 Days
• Field of Search: 257/40, 257/13, 257/103, 313/504
• US Class Current: 257/40
• CPC Class Codes: C08G 61/00 Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule C08G2/00 - C08G16/00 take precedence
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: H01B 1/127 comprising five-membered aromatic rings in the main chain, e.g. polypyrroles, polythiophenes
• CPC Class Codes: H01B 1/128 comprising six-membered aromatic rings in the main chain, e.g. polyanilines, polyphenylenes
• CPC Class Codes: H05B 33/10 Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
• 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: H05B 33/26 characterised by the composition or arrangement of the conductive material used as an electrode

Abstract

This invention provides semiconductive conjugated polymers incorporating electron-withdrawing groups for use in electroluminescent devices, methods for their manufacture, and electroluminescent devices incorporating the polymers. The electron-withdrawing group is conjugatively linked to the polymer chain and is selected so that the polymer exhibits electroluminesence upon application of an electric field to a layer thereof.

Claims

1. A semiconductive conjugated polymer comprising arylene vinylene units forming at least part of the polymer main chain in which a solubilising group is present on at least some of the arylene moieties so as to render the polymer solution processible, and an electron-withdrawing group is conjugatively linked to the polymer main chain, wherein the solubilising group and the electron-withdrawing group are selected so that the polymer exhibits electroluminescence upon application of an electric field to a layer thereof.

2. A semiconductive conjugated polymer according to claim 1, wherein the electron-withdrawing group is conjugatively linked to at least some of the vinylene moieties.

3. A semiconductive conjugated polymer according to claim 1, wherein the electron-withdrawing group is selected to modulate the optical properties of the polymer.

4. A semiconductive conjugated polymer according to claim 3, wherein the electron-withdrawing group is selected to modulate the wavelength of radiation emitted in electroluminescence.

5. A semiconductive conjugated polymer according to claim 1, wherein the electron-withdrawing group comprises a nitrile group, an ester group, an acid amide, a sulfone, a sulfoxide, a trifluoromethyl or a ketone group.

6. A semiconductive conjugated polymer according to claim 1, wherein the solubilising group comprises an alkoxy or alkyl group with 4 or more carbon atoms.

7. A semiconductive conjugated polymer according to claim 1, wherein the polymer is a substantially fully conjugated poly(arylene vinylene) polymer.

8. A semiconductive conjugated polymer according to claim 7, having the following general formula:

space="preserve" listing-type="equation"> Ar-vinylene-Ar'"'"'-vinylene!.sub.n

in which Ar and Ar'"'"' are the same or different and represent arylene groups, each vinylene is substituted with the electron withdrawing group X, and n represents the degree of polymerisation.

18. A method of making a semiconductive conjugated polymer according to claim 1, which method comprises reacting a first compound of general formula

19. A method according to claim 18, wherein the reaction is performed under base catalysis.

20. A method according to claim 19, wherein the base is selected from potassium t-butoxide, tetra-N-butylammonium hydroxide and mixtures thereof.

21. A method according to claim 18, which is performed in the presence of t-butyl alcohol, and/or THF as solvent components.

22. A method according to claim 18, which is performed in the temperature range 20°

to 60°

C.

23. A method according to claim 18, wherein R is hydrogen.

24. A method according to claim 18, wherein X comprises a nitrile group, an ester group, an acid amide, a sulfone, a sulfoxide, a trifluoromethyl or a ketone group.

25. A method according to claim 18, wherein the solubilising group comprises an alkoxy or alkyl group with 4 or more carbon atoms.

26. A method according to claim 18, wherein Ar and Ar'"'"' are both 2,5-dihexyloxyphenylene moieties and X is CN.

27. A method according to claim 18, wherein Ar 2-dodecyloxy,5-methylthio phenylene, Ar'"'"' is 2,5 dihexyloxy phenylene, and X is CN.

28. A method according to claim 18, wherein Ar is 2,6-dihexyloxynaphthylene and Ar'"'"' is 2,5 dihexyloxy phenylene.

29. A method according to claim 18, wherein Ar is a 2,5 dihexyloxy phenylene and Ar'"'"' is a dodecyl-substituted thiophene.

30. A method according to claim 18, wherein Ar'"'"' comprises the unit Ar"-R"-Ar"'"'"' in which Ar" and Ar"'"'"' are the same or different and represent arylene moieties, and R" represents an aliphatic linker group.

31. A method according to claim 30, wherein Ar" and Ar"'"'"' are both p phenylene, X is CN and R" is --O--(CH₂)₈ --O--.

33. An electroluminescent device according to claim 32, wherein the semiconductive conjugated polymer is as defined for claim 1.

9. A semiconductive conjugated polymer, having the general formula:

space="preserve" listing-type="equation"> Ar--CX═

CH--Ar'"'"'--CH═

CX!.sub.n

wherein Ar and Ar'"'"' are the same or different and represent arylene groups, each vinylene is substituted with an electron withdrawing group X, n represents the degree of polymerisation and a solubilising group is present on at least some of the arylene groups so as to render the polymer solution processible; and

wherein the polymer exhibits electroluminscence upon application of an electric field to a layer thereof.

10. A semiconductive conjugated polymer according to claim 9, wherein Ar and Ar'"'"' are both 2,5 dihexyloxy phenylene moieties and X is CN.

11. A semiconductive conjugated polymer according to claim 9, wherein Ar is 2-dodecyloxy,5-methylthio phenylene, Ar'"'"' is 2,5 dihexyloxy phenylene, and X is CN.

12. A semiconductive conjugated polymer according to claim 9, wherein Ar is 2,6-dihexyloxy naphthalene and Ar'"'"' is 2,5 dihexyloxy phenylene.

13. A semiconductive conjugated polymer according to claim 9, wherein Ar is a 2,5 dihexyloxy phenylene and Ar'"'"' is a dodecyl-substituted thiophene.

14. A semiconductive conjugated polymer comprising:

(i) conjugated regions incorporating arylene vinylene units forming part of the polymer main chain in which a solubilising group is present on at least some of the arylene moieties so as to render the polymer solution processible, and an electron-withdrawing group is conjugatively linked to the polymer main chain; and

(ii) unconjugated regions, wherein the solubilising group and the electron-withdrawing group are selected so that the polymer exhibits electroluminescence upon application of an electric field to a layer thereof.

15. A semiconductive conjugated polymer according to claim 14, wherein the conjugated regions comprise distyrylbenzene moieties which incorporate the arylene vinylene units.

16. A semiconductive conjugated polymer according claim 15, having the following general formula:

##STR15## in which at least one of R and R'"'"' is a solubilising group, X is the electron-withdrawing group, and R" is an aliphatic linker group.

17. A semiconductive conjugated polymer according to claim 16, wherein R and R'"'"' are both hexyloxy groups, X is CN and R" is --O--(CH₂)₈ --O--.

35. An electroluminescent device according to claim 32, wherein the semiconductive conjugated polymer is as defined for claim 14.

32. An electroluminescent device comprising a semiconductive layer which comprises an emissive layer of semiconductive conjugated polymer, a first contact layer in contact with a first surface of the semiconductive layer, and a second contact layer in contact with a second surface of the semiconductor layer, wherein the polymer comprises arylene vinylene units forming at least part of the polymer main chain, on which is present a solubilising group so as to render the polymer solution processible, and an electron-withdrawing group is conJugatively linked to the polymer main chain, wherein the solubilising group and the electron-withdrawing group are selected so that the polymer emits radiation upon application of an electric field between the first and second contact layers.

34. An electroluminescent device according to claim 32, wherein the semiconductive conjugated polymer is as defined for claim 9.

36. An electroluminescent device according to claim 32, wherein the semiconductive layer further comprises a hole-transporting polymer layer between the emissive layer and the first contact layer, which hole-transporting polymer layer matches the first contact layer for hole injection.

37. An electroluminescent device according to claim 36, wherein the first contact layer comprises indium-tin oxide and the hole transporting polymer comprises poly(paraphenylenevinylene), polythiophene or polyphenylene.

38. An electroluminescent device according to claim 32, wherein the second contact layer comprises a metal selected from calcium, aluminium and gold.

39. An electroluminescent device according to claim 38, wherein the second contact layer comprises aluminum.