Phosphorescent iridium complexes
View Patent ↗An OLED device comprises a cathode, an anode, and located therebetween a light emitting layer containing a compound represented by formula (I): A m -M-B n (I) wherein m+n=2 or 3 and neither m nor n is 0; M is Ir, Pt, Os, Ru, Rh, or Pd; A m includes at least one ligand A having a triplet energy of at least 2.9 eV as measured in a homoleptic complex of M and A; and B is represented by the formula (II): wherein Q represents an atomic group forming a nitrogen-containing heterocyclic ring; and R5, R6, R7, R8 and R5′ independently represent a hydrogen atom or a substituent.
1. An OLED device comprising a cathode, an anode, and located therebetween a light emitting layer containing a compound represented by formula (I):
A m -M-B n (I)
wherein
m+n=2 or 3 and neither m nor n is 0;
M is Ir, Pt, Os, Ru, Rh, Re or Pd;
A m includes at least one ligand A having a triplet energy of at least 2.9 eV as measured in a homoleptic complex of M and A; and
B is represented by the formula (II):
wherein
Q represents an atomic group forming a nitrogen-containing heterocyclic ring; and R5, R6, R7, R8 and R5′ independently represent a hydrogen atom or a substituent; and
wherein at least one ligand A of formula (I) is a 1-phenylpyrazole group represented by formula (II):
wherein R 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, and R 3 ′ are each hydrogen or an independently selected substituent.
2. The device of claim 1 wherein ligand A has a triplet energy of at least 3.0 eV as measured in a homoleptic complex of M and A.
3. The device of claim 1 wherein ligand A has a triplet energy of at least 3.1 eV as measured in a homoleptic complex of M and A.
4. The device of claim 1 wherein at least one of R 1 , R 2 , R 3 , or R 4 is an electron withdrawing group having a positive Hammett's sigma para or meta value.
5. The device of claim 4 wherein the electron withdrawing group is selected from those having a Hammett's sigma pan or meta value of at least 0.3.
6. The device of claim 4 wherein the electron withdrawing group is selected from the group consisting of F, CF 3 , CN, NO 2 , C(O)OR, C(O)R, C(O)NR,P(O)RR′, P(S)RR′, SO 2 , SOR, SO 2 R, SO 3 R, BRR′, and B(OR) 2 groups wherein each R and R′ is a substituent.
7. The device of claim 1 wherein at least one R 1 ′, R 2 ′, or R 3 ′ is represented by an electron donating group having a negative Hanimett's sigma para or meta value.
8. The device of claim 7 wherein the electron donating group is selected from C 1 -C 20 alkyl, C 1 -C 20 alkoxy, NRR′, and thiophene groups wherein each R and R′ is a substituent.
9. The device of claim 1 wherein at least one ligand A of formula (I) is selected from the group consisting of:
10. The device of claim 1 wherein at least one ligand B of formula (I) is a pyridylpyrazole.
11. The device of claim 10 wherein ligand B is represented by formula (III):
wherein each R 5 , R 6 , R 7 , R 8 , R 5 ′, and R 6 ′ is independently a hydrogen or substituent.
12. The device of claim 11 wherein ligand B is independently substituted with at least one electron withdrawing group having a positive Hammett's sigma pam or meta value at R 5 ′, or R 6 ′.
13. The device of claim 12 wherein the electron withdrawing group is selected from those having a Hanimett's sigma para or meta value of at least 0.3.
14. The device of claim 13 wherein the electron withdrawing group is selected from the group consisting of F, CF 3 , CN, NO 2 , C(O)OR, C(O)R, C(O)NR,P(O)RR′, P(S)RR′, SO 2 , SOR, SO 2 R, SO 3 R, BRR′, and B(OR) 2 groups wherein each R and R′ is a substituent.
15. The device of claim 11 wherein ligand B is independently substituted with at least one electron donating group having a negative Rammett's sigma para or meta value at R 5 , R 6 , R 7 , or R 8 .
16. The device of claim 15 wherein the electron donating group is selected from C 1 -C 20 alkyl, C 1 -C 20 alkoxy, NRR′, and thiophene groups wherein each R and R′ is a substituent.
17. The device of claim 1 wherein ligand B of formula (I) is selected from the group consisting of:
18. The device of claim 1 wherein n is 2 and m is 1.
19. The device of claim 1 wherein n is 1 and m is 2.
20. The device of claim 1 wherein the device emits white light.
21. The device of claim 1 wherein the light emitted from the light-emitting layer is blue.
22. The device of claim 1 wherein the compound having formula (I) is in a layer which comprises a polymer.
23. The device of claim 1 wherein the compound having formula (I) is in a layer adjacent to a layer which comprises a polymer.
24. The device of claim 1 wherein the compound having formula (I) is polvmenc.
25. A stacked device comprising the device of claim 1 .
26. The device of claim 1 wherein the light emitting layer contains a host material that has a triplet energy higher than that of the compound having formula (I) and the host is selected from: 4,4′-N,N′-dicarbazole-biphenyl (CBP), 2,2′-dimethyl-4,4′-N, N′-dicarbazole-biphenyl, m-(N,N′-dicarbazole)benzene, poly(N-vinylcarbazole) compounds, diphenyldi(o-tolyl)silane and p-bis(triphenylsilyl)silane.