Organic element for electroluminescent devices

1. An OLED device comprising a light-emitting layer (LEL) containing a host and an emitting dopant located between a cathode and an anode wherein the dopant is an orange-red light emitting rubrene derivative represented by formula (I):

wherein:

a) there are identical oxy, aza or thio groups at the 2- and 8-positions;

b) the phenyl rings in the 5- and 11-positions contain only para-substituents identical to the oxy, aza or thio groups in paragraph a);

c) the phenyl rings in the 6- and 12-positions are substituted or unsubstituted; and

provided that when a single substituent is present on both phenyl rings in paragraph c), said substituent is not a methoxy group located at the para-position, and provided that all of the substituents are selected so that the wavelength of maximum emission (λ max ) in the EL device is such that 570 nm<λ max ≦650 nm.

2. The device of claim 1 comprising a further light-emitting compound to provide a white light emission.

3. The device of claim 2 further comprising a blue light-emitting compound to provide a white light emission.

4. The device of claim 2 further comprising a filter over-lying the device.

5. The device of claim 2 wherein the layer comprises a host and dopant where the dopant is present in an amount of up to 10%-wt of the host.

6. The device of claim 5 wherein the dopant is present in an amount of 0.1–5.0%-wt of the host.

7. The device of claim 1 wherein the dopant is represented by formula (IV):

wherein

R 2 is a substituent group;

n is 0–5;

provided that the R 2 , their location and n value on one ring are the same as those on the second ring; and

provided further that when n is 1, R 2 is not para-methoxy.

8. The device of claim 1 wherein the host is an amine compound.

9. The device of claim 1 wherein the host comprises N,N′-di-1 -naphthalenyl-N,N′-diphenyl-4,4′-diaminobiphenyl.

10. The device of claim 1 wherein the substituents are selected to provide a reduced loss of initial luminance compared to the device containing no rubrene compound.

11. The device of claim 1 wherein the rubrene compound is selected from the following:

12. A light emitting device containing the OLED device of claim 1 .

13. A light-emitting display containing the OLED device of claim 1 .

14. A method of emitting light comprising subjecting the device of claim 1 to an applied voltage.

15. An OLED device comprising a light-emitting layer (LEL) containing a host and an emitting dopant located between a cathode and an anode wherein the dopant is an orange-red light emitting rubrene derivative represented by formula (II):

wherein

R 1 is selected from alkyl, carbocyclic, and heterocyclic groups;

R 2 is a substituent group;

X is oxygen, sulfur or N(R 3 ) wherein R 3 is selected from alkyl, carbocyclic and heterocyclic groups or taken with R 1 may form a ring;

n is 0–5;

provided that all R 1 groups are the same;

provided further, that the R 2 substituents, their location and n value on one ring, are the same as those on the second ring; and

provided still further that when X is oxygen and n is 1, R 2 is not para-methoxy, and provided that all of the substituents are selected so that the wavelength of maximum emission (λ max ) in the EL device is such that 570 nm<λ max ≦650 nm.

16. The device of claim 15 wherein the dopant is represented by formula (III):

wherein

R 1 is selected from alkyl, carbocyclic, and heterocyclic groups;

R 2 is a substituent group;

n is 0–5;

provided that all R 1 groups are the same;

provided further, that the R 2 , their location and n value on one ring are the same as those on the second ring; and

provided still further that when n is 1, R 2 is not para-methoxy.

17. The device of claim 15 wherein R 1 is a carbocyclic or heterocyclic group.

18. The device of claim 15 wherein R 1 is an alkyl or aryl group.

19. The device of claim 15 wherein R 1 is represented by the formula;

wherein each of R 4 , R 5 and R 6 is hydrogen or an independently selected substituent.

20. The device of claim 19 wherein R 4 , R 5 and R 6 taken together may form a mono- or multi-cyclic ring system.

21. The device of claim 15 wherein R 1 is represented by the formula;

wherein each of R 4 , R 5 and R 6 is hydrogen or an independently selected substituent with no more than one being hydrogen.

22. The device of claim 15 comprising a further light-emitting compound to provide a white light emission.

23. The device of claim 22 further comprising a blue light-emitting compound to provide a white light emission.

24. The device of claim 22 further comprising a filter over-lying the device.

25. The device of claim 15 wherein R 2 is located in meta and para positions of the phenyl group.

26. The device of claim 15 wherein R 2 is phenyl.

27. The device of claim 15 wherein R 2 is tert-butyl.

28. The device of claim 15 wherein R 2 is selected from fluorine, trifluoromethyl, pentafluoroethyl and fluorinated-phenyl groups.

29. The device of claim 15 wherein R 2 is a fluorine-containing group.

30. The device of claim 15 wherein R 2 is fluorine.

31. The device of claim 15 wherein R 1 is a fluorine-containing group.

32. The device of claim 15 wherein R 2 are independently selected from the group consisting of fluorine, fluorine containing groups, alkyl, aryl, alkoxy and aryloxy groups.

33. The device of claim 15 wherein the layer comprises a host and dopant where the dopant is present in an amount of up to 10%-wt of the host.

34. The device of claim 33 wherein the dopant is present in an amount of 0.1–5.0%-wt of the host.

35. An OLED device comprising a light-emitting layer (LEL) containing a host and an emitting dopant located between a cathode and an anode wherein the dopant is an orange-red light emitting rubrene derivative represented by formula (I):

wherein:

a) there are identical oxy, aza or thio groups at the 2- and 8-positions;

b) the phenyl rings in the 5- and 11-positions contain only para-substituents identical to the oxy, aza or thio groups in paragraph a);

c) the phenyl rings in the 6- and 12-positions are substituted or not; and

provided that the rubrene derivative has a wavelength of maximum emission (λ max ) in ethyl acetate solution such that 560 nm<λ max ≦650 nm and a wavelength of maximum emission (λ max ) in the EL device such that 570 nm<≦650 nm.

36. An OLED device of claim 35 wherein the rubrene derivative has a wavelength of maximum emission (λ max ) in ethyl acetate solution such that 565 nm<λ max ≦625 nm and a wavelength of maximum emission (λ max ) in the EL device such that 570 nm<λ max ≦650 nm.