U.S. patent application number 09/879014 was filed with the patent office on 2002-09-05 for electroluminescent iridium compounds with fluorinated phenylpyridines, phenylpyrimidines, and phenylquinolines and devices made with such compounds.
Invention is credited to Grushin, Vladimir, Petrov, Viacheslav A., Wang, Ying.
Application Number | 20020121638 09/879014 |
Document ID | / |
Family ID | 26909953 |
Filed Date | 2002-09-05 |
United States Patent
Application |
20020121638 |
Kind Code |
A1 |
Grushin, Vladimir ; et
al. |
September 5, 2002 |
Electroluminescent iridium compounds with fluorinated
phenylpyridines, phenylpyrimidines, and phenylquinolines and
devices made with such compounds
Abstract
The present invention is generally directed to
electroluminescent Ir(III) compounds, the substituted
2-phenylpyridines, phenylpyrimidines, and phenylquinolines that are
used to make the Ir(III) compounds, and devices that are made with
the Ir(III) compounds.
Inventors: |
Grushin, Vladimir;
(Hockessin, DE) ; Petrov, Viacheslav A.;
(Hockessin, DE) ; Wang, Ying; (Wilmington,
DE) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
26909953 |
Appl. No.: |
09/879014 |
Filed: |
June 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60215362 |
Jun 30, 2000 |
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60224273 |
Aug 10, 2000 |
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Current U.S.
Class: |
257/40 ; 257/103;
257/79 |
Current CPC
Class: |
C09K 11/06 20130101;
H01L 51/5012 20130101; C07D 213/26 20130101; C07D 213/61 20130101;
Y10S 428/917 20130101; C07F 15/0033 20130101; C07D 215/04 20130101;
C09K 2211/1014 20130101; C09K 2211/185 20130101; H01L 51/0084
20130101; H01L 51/50 20130101; C07D 239/26 20130101; C09K 2211/1029
20130101; H01L 51/005 20130101; C07D 213/68 20130101; C07D 213/30
20130101; C09K 2211/1007 20130101; H01L 51/0085 20130101; H05B
33/14 20130101; C09K 2211/1011 20130101 |
Class at
Publication: |
257/40 ; 257/79;
257/103 |
International
Class: |
H01L 035/24; H01L
051/00; H01L 027/15; H01L 031/12; H01L 033/00 |
Claims
What is claimed is:
1. An organic electronic device comprising an emitting layer
wherein at least 20% by weight of the emitting layer comprises at
least one compound having a formula
below:IrL.sup.aL.sup.bL.sup.c.sub.xL'.sub.yL".sub.z,wher- e: x=0 or
1, y=0, 1 or 2, and z=0 or 1, with the proviso that: x=0 or y+z=0
and when y=2 then z=0; L'=a bidentate ligand or a monodentate
ligand, and is not a phenylpyridine, phenylpyrimidine, or
phenylquinoline; with the proviso that: when L' is a monodentate
ligand, y+z=2, and when L' is a bidentate ligand, z=0; L" a
monodentate ligand, and is not a phenylpyridine, and
phenylpyrimidine, or phenylquinoline; and L.sup.a, L.sup.b and
L.sup.c are alike or different from each other and each of L.sup.a,
L.sup.b and L.sup.c has structure (I) below: 9wherein: adjacent
pairs of R.sub.1-R.sub.4 and R.sub.5-R.sub.8 can be joined to form
a five- or six-membered ring, at least one of R.sub.1-R.sub.8 is
selected from F, C.sub.nF.sub.2n+1, OC.sub.nF.sub.2n+1, and
OCF.sub.2X, where n=1-6 and X=H, Cl, or Br, and A=C or N, provided
that when A=N, there is no R.sub.1.
2. The device of claim 1 wherein x=1, y=0, and z=0.
3. The device of claim 2 wherein A=C and none of R.sub.1-R.sub.8 is
selected from nitro.
4. The device of claim 1 wherein R.sub.3 is CF.sub.3.
5. The device of claim 4 wherein at least one of R.sub.5-R.sub.8 is
selected from F, C.sub.nF.sub.2n+1, OC.sub.nF.sub.2n+1, and
OCF.sub.2X, where n=1-6 and X.dbd.H, Cl, or Br.
6. The device of claim 2 wherein A=C, R.sub.3.dbd.CF.sub.3,
R.sub.7.dbd.F, and R.sub.1, R.sub.2, R.sub.4-R.sub.6 and
R.sub.8.dbd.H.
7. The device of claim 2 wherein A=C, R.sub.3 and
R.sub.6.dbd.CF.sub.3, and R.sub.1, R.sub.2, R.sub.4, R.sub.5,
R.sub.7 and R.sub.8.dbd.H.
8. The device of claim 2 wherein A=C, R.sub.3=CF.sub.3, R.sub.6 and
R.sub.8.dbd.F, and R.sub.1, R.sub.2, R.sub.4, R.sub.5, and
R.sub.7.dbd.H.
9. The device of claim 1 wherein x=0 and y=1 having a structure
(VI) below: 10
10. An organic electronic device comprising an emitting layer
wherein the emitting layer comprises a diluent and less than 20% by
weight of at least one compound that has a formula
below:IrL.sup.aL.sup.bL.sup.c,where- : L.sup.a, L.sup.b and L.sup.c
are alike or different from each other and each of L.sup.a, L.sup.b
and L.sup.c has structure (I) below: 11wherein: adjacent pairs of
R.sub.1-R.sub.4 and R.sub.5-R.sub.8 can be joined to form a five-
or six-membered ring, at least one of R.sub.1-R.sub.8 is selected
from F, C.sub.nF.sub.2n+1, OC.sub.nF.sub.2n+1, and OCF.sub.2X,
where n=1-6 and X.dbd.H, Cl, or Br, and A=C or N, provided that
when A=N, there is no R.sub.1.
11. The device of claim 10 wherein the diluent is selected from
poly(N-vinyl carbazole), polysilane, 4,4'-N,N'-dicarbazole
biphenyl, and tertiary aromatic amines.
12. The device of claim 1, further comprising a hole transport
layer selected from
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-
-diamine (TPD), 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane
(TAPC),
N,N'-bis(4-methylphenyl)-N,N'-bis(4-ethylphenyl)-[1,1'-(3,3'-dimethyl)bip-
henyl]-4,4'-diamine (ETPD),
tetrakis-(3-methylphenyl)-N,N,N',N'-2,5-phenyl- enediamine (PDA),
-phenyl-4-N,N-diphenylaminostyrene (TPS),
p-(diethylamino)-benzaldehyde diphenylhydrazone (DEH),
triphenylamine (TPA),
bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane
(MPMP),
1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyr-
azoline (PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane
(DCZB),
N,N,N',N'-tetrakis(4-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine
(TTB), porphyrinic compounds, and combinations thereof.
13. The device of claim 1, further comprising an electron transport
layer selected from tris(8-hydroxyquinolato)aluminum,
2,9-dimethyl-4,7-diphenyl- -1,10-phenanthroline (DDPA),
4,7-diphenyl-1,1 0-phenanthroline (DPA),
2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD),
3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ),
and combinations thereof.
14. A compound having a formula selected from fac-Ir(L).sub.3,
mer-Ir(L).sub.3, and combinations thereof, where L is selected from
group 1-a through 1-m and 1-q through 1-v as shown in Table 1, and
has structure (I) below: 12wherein: adjacent pairs of
R.sub.1-R.sub.4 and R.sub.5-R.sub.8 can be joined to form a five-
or six-membered ring, at least one of R.sub.1-R.sub.8 is selected
from F, C.sub.nF.sub.2n+1, OC.sub.nF.sub.2n+1, and OCF.sub.2X,
where n=1-6 and X.dbd.H, Cl, or Br, and A=C or N, provided that
when A=N, there is no R.sub.1.
15. A compound having a structure selected from structures (IV),
(V), (VI), (IX) and (X) below: 13
16. An organic electronic device comprising an emitting layer that
comprises a compound selected from the following (i) and (ii): (i)
a compound having a formula selected from fac-Ir(L).sub.3,
mer-Ir(L).sub.3, and combinations thereof, where L is a group
selected from 1-a through 1-m and 1-q through 1-v, as shown in
Table 1 and has structure (I) below: 14wherein: adjacent pairs of
R.sub.1-R.sub.4 and R.sub.5-R.sub.8 can be joined to form a five-
or six-membered ring, at least one of R.sub.1-R.sub.8 is selected
from F, C.sub.nF.sub.2n+1, OC.sub.nF.sub.2n+1, and OCF.sub.2X,
where n=1-6 and X.dbd.H, Cl, or Br, and A=C or N, provided that
when A=N, there is no R.sub.1; (ii) a compound having one of
structures (IV), (V), (VI), (IX), and (X) below: 15
17. The device of claim 16 wherein the emitting layer further
comprises a diluent.
18. The device of claim 17 wherein the diluent is selected from
poly(N-vinyl carbazole), polysilane, 4,4'-N,N'-dicarbazole
biphenyl, and tertiary aromatic amines.
19. A compound selected from compounds 2-a through 2-aa as shown in
Table 2, having structure (II) below: 16wherein: R.sub.9 is H;
adjacent pairs of R.sub.1-R.sub.4 and R.sub.5-R.sub.8 can be joined
to form a five- or six-membered ring; at least one of
R.sub.1-R.sub.8 is selected from F, C.sub.nF.sub.2n+1,
OC.sub.nF.sub.2n+1, and OCF.sub.2X, where n=1-6 and X.dbd.H, Cl, or
Br, and A=C or N, provided that when A=N, there is no R.sub.1.
20. A compound having structure (III) below: 17wherein
R.sub.17.dbd.CF.sub.3 and R.sub.10-R.sub.16 and
R.sub.18-R.sub.20.dbd.H.
21. A compound having structure VII below: 18wherein: B=H,
CH.sub.3, or C.sub.2H.sub.5; L.sup.a, L.sup.b, L.sup.c, and L.sup.d
are the same or different from each other; and each of L.sup.a,
L.sup.b, L.sup.c, and L.sup.d has structure (I) below: 19wherein:
adjacent pairs of R.sub.1-R.sub.4 and R.sub.5-R.sub.8 can be joined
to form a five- or six-membered ring, at least one of
R.sub.1-R.sub.8 is selected from F, C.sub.nF.sub.2n+1,
OC.sub.nF.sub.2n+1, and OCF.sub.2X, where n=1-6 and X.dbd.H, Cl, or
Br, and A=C or N, provided that when A=N, there is no R.sub.1.
22. The compound of claim 21 wherein:
L.sup.a=L.sup.b=L.sup.c=L.sup.d; B=H; R.sub.3.dbd.CF.sub.3;
R.sub.7.dbd.F; R.sub.1, R.sub.2, R.sub.4-R.sub.6 and R.sub.8.dbd.H.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to electroluminescent complexes of
iridium(III) with fluorinated phenylpyridines, phenylpyrimidines,
and phenylquinolines. It also relates to electronic devices in
which the active layer includes an electroluminescent Ir(III)
complex.
[0003] 2. Description of the Related Art
[0004] Organic electronic devices that emit light, such as
light-emitting diodes that make up displays, are present in many
different kinds of electronic equipment. In all such devices, an
organic active layer is sandwiched between two electrical contact
layers. At least one of the electrical contact layers is
light-transmitting so that light can pass through the electrical
contact layer. The organic active layer emits light through the
light-transmitting electrical contact layer upon application of
electricity across the electrical contact layers.
[0005] It is well known to use organic electroluminescent compounds
as the active component in light-emitting diodes. Simple organic
molecules such as anthracene, thiadiazole derivatives, and coumarin
derivatives are known to show electroluminescence. Semiconductive
conjugated polymers have also been used as electroluminescent
components, as has been disclosed in, for example, Friend et al.,
U.S. Pat. No. 5,247,190, Heeger et al., U.S. Pat. No. 5,408,109,
and Nakano et al., Published European Patent Application 443 861.
Complexes of 8-hydroxyquinolate with trivalent metal ions,
particularly aluminum, have been extensively used as
electroluminescent components, as has been disclosed in, for
example, Tang et al., U.S. Pat. No. 5,552,678.
[0006] Burrows and Thompson have reported that
fac-tris(2-phenylpyridine) iridium can be used as the active
component in organic light-emitting devices. (Appl. Phys. Lett.
1999, 75, 4.) The performance is maximized when the iridium
compound is present in a host conductive material. Thompson has
further reported devices in which the active layer is poly(N-vinyl
carbazole) doped with fac-tris[2-(4',5'-difluorophenyl)pyrid-
ine-C'.sup.2,N]iridium(III). (Polymer Preprints 2000, 41(1),
770.)
[0007] However, there is a continuing need for electroluminescent
compounds having improved efficiency.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to an iridium compound
(generally referred as "Ir(III) compounds") having at least two
2-phenylpyridine ligands in which there is at least one fluorine or
fluorinated group on the ligand. The iridium compound has the
following First Formula:
IrL.sup.aL.sup.bL.sup.c.sub.xL'.sub.yL".sub.z (First Formula)
[0009] where:
[0010] x=0 or 1, y=0, 1 or 2, and z=0 or 1, with the proviso
that:
[0011] x=0 or y+z=0 and
[0012] when y=2 then z=0;
[0013] L'=a bidentate ligand or a monodentate ligand, and is not a
phenylpyridine, phenylpyrimidine, or phenylquinoline; with the
proviso that:
[0014] when L' is a monodentate ligand, y+z=2, and
[0015] when L' is a bidentate ligand, z=0;
[0016] L"=a monodentate ligand, and is not a phenylpyridine, and
phenylpyrimidine, or phenylquinoline; and
[0017] L.sup.a, L.sup.b and L.sup.c are alike or different from
each other and each of L.sup.a, L.sup.b and L.sup.c has structure
(I) below: 1
[0018] wherein:
[0019] adjacent pairs of R.sub.1-R.sub.4 and R.sub.5-R.sub.8 can be
joined to form a five- or six-membered ring,
[0020] at least one of R.sub.1-R.sub.8 is selected from F,
C.sub.nF.sub.2n+1, OC.sub.nF.sub.2n+1, and OCF.sub.2X, where n=1-6
and X=H, Cl, or Br, and
[0021] A=C or N, provided that when A=N, there is no R.sub.1.
[0022] In another embodiment, the present invention is directed to
substituted 2-phenylpyridine, phenylpyrimidine, and phenylquinoline
precursor compounds from which the above Ir(III) compounds are
made. The precursor compounds have a structure (II) or (III) below:
2
[0023] where A and R.sub.1-R.sub.8 are as defined in structure (I)
above, and R.sub.9 is H. 3
[0024] where:
[0025] at least one of R.sub.10-R.sub.19 is selected from F,
C.sub.nF.sub.2n+1, OC.sub.nF.sub.2n+1, and OCF.sub.2X, where n=1-6
and X=H, Cl, or Br, and R.sub.20 is H.
[0026] It is understood that there is free rotation about the
phenyl-pyridine, phenyl-pyrimidine and the phenyl-quinoline bonds.
However, for the discussion herein, the compounds will be described
in terms of one orientation.
[0027] In another embodiment, the present invention is directed to
an organic electronic device having at least one emitting layer
comprising the above Ir(III) compound, or combinations of the above
Ir(III) compounds.
[0028] As used herein, the term "compound" is intended to mean an
electrically uncharged substance made up of molecules that further
consist of atoms, wherein the atoms cannot be separated by physical
means. The term "ligand" is intended to mean a molecule, ion, or
atom that is attached to the coordination sphere of a metallic ion.
The term "complex", when used as a noun, is intended to mean a
compound having at least one metallic ion and at least one ligand.
The term "group" is intended to mean a part of a compound, such a
substituent in an organic compound or a ligand in a complex. The
term "facial" is intended to mean one isomer of a complex,
Ma.sub.3b.sub.3, having octahedral geometry, in which the three "a"
groups are all adjacent, i.e. at the corners of one face of the
octahedron. The term "meridional" is intended to mean one isomer of
a complex, Ma.sub.3b.sub.3, having octahedral geometry, in which
the three "a" groups occupy three positions such that two are trans
to each other. The phrase "adjacent to," when used to refer to
layers in a device, does not necessarily mean that one layer is
immediately next to another layer. On the other hand, the phrase
"adjacent R groups," is used to refer to R groups that are next to
each other in a chemical formula (i.e., R groups that are on atoms
joined by a bond). The term "photoactive" refers to any material
that exhibits electroluminescence and/or photosensitivity.
DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a schematic diagram of a light-emitting device
(LED).
[0030] FIG. 2 is a schematic diagram of an LED testing
apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] The Ir(III) compounds of the invention have the First
Formula Ir(III)L.sup.aL.sup.bL.sup.c.sub.xL'.sub.y above.
[0032] The above Ir(III) compounds are frequently referred to as
cyclometalated complexes: Ir(III) compounds having the following
Second Formula is also frequently referred to as a
bis-cyclometalated complex.:
IrL.sup.aL.sup.bL'.sub.yL".sub.z (Second Formula)
[0033] where:
[0034] y, z, L.sup.a, L.sup.b,L', and L" are as defined in the
First Formula above.
[0035] Ir(III) compounds having the following Third Formula is also
frequently referred to as a tris-cyclometalated complex.:
IrL.sup.aL.sup.bL.sup.c (Third Formula)
[0036] where:
[0037] L.sup.a, L.sup.b and L.sup.c are as defined in the First
Formula described above.
[0038] The preferred cyclometalated complexes are neutral and
non-ionic, and can be sublimed intact. Thin films of these
materials obtained via vacuum deposition exhibit good to excellent
electroluminescent properties. Introduction of fluorine
substituents into the ligands on the iridium atom increases both
the stability and volatility of the complexes. As a result, vacuum
deposition can be carried out at lower temperatures and
decomposition of the complexes can be avoided. Introduction of
fluorine substituents into the ligands can often reduce the
non-radiative decay rate and the self-quenching phenomenon in the
solid state. These reductions can lead to enhanced luminescence
efficiency. Variation of substituents with electron-donating and
electron-withdrawing properties allows for fine-tuning of
electroluminescent properties of the compound and hence
optimization of the brightness and efficiency in an
electroluminescent device.
[0039] While not wishing to be bound by theory, it is believed that
the emission from the iridium compounds is ligand-based, resulting
from metal-to-ligand charge transfer. Therefore, compounds that can
exhibit electroluminescence include those of compounds of the
Second Formula IrL.sup.aL.sup.bL' .sub.yL".sub.z above, and the
Third Formula IrL.sup.aL.sup.bL.sup.c above, where all L.sup.a,
L.sup.b, and L.sup.c in the Third Formula are phenylpyridines,
phenylpyrimidines, or phenylquinolines. The R.sub.1-R.sub.8 groups
of structures (I) and (II), and the R.sub.10-R.sub.19 groups of
structure (III) above may be chosen from conventional substitutents
for organic compounds, such as alkyl, alkoxy, halogen, nitro, and
cyano groups, as well as fluoro, fluorinated alkyl and fluorinated
alkoxy groups. The groups can be partially or fully fluorinated
(perfluorinated). Preferred iridium compounds have all
R.sub.1-R.sub.8 and R.sub.10-R.sub.19 substituents selected from
fluoro, perfluorinated alkyl (C.sub.nF.sub.2n+1) and perfluorinated
alkoxy groups (OC.sub.nF.sub.2n+1), where the perfluorinated alkyl
and alkoxy groups have 1-6 carbon atoms, or a group of the formula
OCF.sub.2X, where X.dbd.H, Cl, or Br.
[0040] It has been found that the electroluminescent properties of
the cyclometalated iridium complexes are poorer when any one or
more of the R.sub.1-R.sub.8 and R.sub.10-R.sub.19 groups is a nitro
group. Therefore, it is preferred that none of the R.sub.1-R.sub.8
and R.sub.10-R.sub.19 groups is a nitro group.
[0041] The nitrogen-containing ring can be a pyridine ring, a
pyrimidine or a quinoline. It is preferred that at least one
fluorinated substituent is on the nitrogen-containing ring; most
preferably CF.sub.3.
[0042] Any conventional ligands known to transition metal
coordination chemistry is suitable as the L' and L" ligands.
Examples of bidentate ligands include compounds having two
coordinating groups, such as ethylenediamine and acetylacetonate,
which may be substituted. Examples of monodentate ligands include
chloride and nitrate ions and mono-amines. It is preferred that the
iridium complex be neutral and sublimable. If a single bidentate
ligand is used, it should have a net charge of minus one (-1). If
two monodentate ligands are used, they should have a combined net
charge of minus one (-1). The bis-cyclometalated complexes can be
useful in preparing tris-cyclometalated complexes where the ligands
are not all the same.
[0043] In a preferred embodiment, the iridium compound has the
Third Formula IrL.sup.aL.sup.bL.sup.c as described above.
[0044] In a more preferred embodiment, L.sup.a=L.sup.b=L.sup.C.
These more preferred compounds frequently exhibit a facial
geometry, as determined by single crystal X-ray diffraction, in
which the nitrogen atoms coordinated to the iridium are trans with
respect to carbon atoms coordinated to the iridium. These more
preferred compounds have the following Fourth Formula:
fac-Ir(L.sup.a).sub.3 (Fourth Formula)
[0045] where L.sup.a has structure (I) above.
[0046] The compounds can also exhibit a meridional geometry in
which two of the nitrogen atoms coordinated to the iridium are
trans to each other. These compounds have the following Fifth
Formula:
mer-Ir(L.sup.a).sub.3 (Fifth Formula)
[0047] where L.sup.a has structure (I) above.
[0048] Examples of compounds of the Fourth Formula and Fifth
Formula above are given in Table I below:
1TABLE 1 Compound A R.sub.1 R.sub.2 R.sub.3 R.sub.4 R.sub.5 R.sub.6
R.sub.7 R.sub.8 Formula 1-a C H H CF.sub.3 H H H H H Fourth 1-b C H
H CF.sub.3 H H H F H Fourth 1-c C H H CF.sub.3 H F H H H Fourth 1-d
C H H H H F H H H Fourth 1-e C H H CF.sub.3 H H CF.sub.3 H H Fourth
1-f C H H H H H CF.sub.3 H H Fourth 1-g C H H H H H H F H Fourth
1-h C Cl H CF.sub.3 H H H H H Fourth 1-i C H H CF.sub.3 H H H
OCH.sub.3 H Fourth 1-j C H H CF.sub.3 H H F H H Fourth 1-k C H H
NO.sub.2 H H CF.sub.3 H H Fourth 1-1 C H H CF.sub.3 H H H OCF.sub.3
H Fourth 1-m N -- CF.sub.3 H H H H F H Fourth 1-q C H H CF.sub.3 H
H OCH.sub.3 H H Fourth 1-r C H OCH.sub.3 H H H H CF.sub.3 H Fourth
1-s C H H H H F H F H Fourth and Fifth 1-t C H H CF.sub.3 H H F H F
Fifth 1-u C H H CF.sub.3 H F H F H Fifth 1-v C H H CF.sub.3 H H H F
H Fifth
[0049] Examples compounds of the Second Formula
IrL.sup.aL.sup.bL'.sub.yL"- .sub.z above include compounds 1-n,
1-o, 1-p, 1-w and 1-x, respectively having structure (IV), (V),
(VI), (IX) and (X) below: 4
[0050] The iridium complexes of the Third Formula
IrL.sup.aL.sup.bL.sup.c above are generally prepared from the
appropriate substituted 2-phenylpyridine, phenylpyrimidine, or
phenylquinoline. The substituted 2-phenylpyridines,
phenylpyrimidines, and phenylquinolines, as shown in Structure (II)
above, are prepared, in good to excellent yield, using the Suzuki
coupling of the substituted 2-chloropyridine, 2-chloropyrimidine or
2-chloroquinoline with arylboronic acid as described in O. Lohse,
P.Thevenin, E. Waldvogel Synlett, 1999, 45-48. This reaction is
illustrated for the pyridine derivative, where X and Y represent
substituents, in Equation (1) below: 5
[0051] Examples of 2-phenylpyridine and 2-phenylpyrimidine
compounds, having structure (II) above, are given in Table 2
below:
2TABLE 2 Compound A R.sub.1 R.sub.2 R.sub.3 R.sub.4 R.sub.5 R.sub.6
R.sub.7 R.sub.8 R.sub.9 2-a C H H CF.sub.3 H F H H H H 2-b C H H
CF.sub.3 H H CF.sub.3 H H H 2-c C H H NO.sub.2 H H CF.sub.3 H H H
2-d C H H CF.sub.3 H H F H H H 2-e C H H CF.sub.3 H H H CH.sub.3O H
H 2-f C Cl H CF.sub.3 H H H H H H 2-g C H H H CH.sub.3 H H F H H
2-h N -- H H H H H F H H 2-i C H H CF.sub.3 H H H CF.sub.3O H H 2-j
N -- CF.sub.3 H H F H H H H 2-k C H H CF.sub.3 H H H F H H 2-l C
CF.sub.3 H H H H H H H H 2-m C Cl H CF.sub.3 H H H F H H 2-n C
CF.sub.3 H H H H H F H H 2-o C CF.sub.3 H H H H H CH.sub.3O H H 2-p
C Cl H CF.sub.3 H H H CH.sub.3O H H 2-q N -- CF.sub.3 H H H H F H H
2-r C Cl H CF.sub.3 H H H H H F 2-s C H H CF.sub.3 H H H H H H 2-t
C Cl H H H F H H H H 2-v C H H CF.sub.3 H H CH.sub.3O H H H 2-w C H
CH.sub.3O H H H H CF.sub.3 H H 2-x C H H H H H F F H H 2-y C H H
CF.sub.3 H H F H F H 2-z C H H CF.sub.3 H F H F H H 2-aa C H H Br H
H H Br H H
[0052] One example of a substituted 2-phenylquinoline compound,
having structure (III) above, is compound 2-u, which has
R.sub.17.dbd.CF.sub.3 and R.sub.10-R.sub.16 and
R.sub.18-R.sub.20.dbd.H.
[0053] The 2-phenylpyridines, pyrimidines, and quinolines thus
prepared are used for the synthesis of the cyclometalated iridium
complexes. A convenient one-step method has been developed
employing commercially available iridium trichloride hydrate and
silver trifluoroacetate. The reactions are generally carried out
with an excess of 2-phenylpyridine, pyrimidine, or quinoline,
without a solvent, in the presence of 3 equivalents of
AgOCOCF.sub.3. This reaction is illustrated for a 2-phenylpyridine
in Equation (2) below: 6
[0054] The tris-cyclometalated iridium complexes were isolated,
purified, and fully characterized by elemental analysis, .sup.1H
and .sup.19F NMR spectral data, and, for compounds 1-b, 1-c, and
1-e, single crystal X-ray diffraction. In some cases, mixtures of
isomers are obtained. Often the mixture can be used without
isolating the individual isomers.
[0055] The iridium complexes having the Second Formula
IrL.sup.aL.sup.bL'.sub.YL".sub.z above, may, in some cases, be
isolated from the reaction mixture using the same synthetic
procedures as preparing those having Third Formula
IrL.sup.aL.sup.bL.sup.c above. The complexes can also be prepared
by first preparing an intermediate iridium dimer having structure
VII below: 7
[0056] wherein:
[0057] B.dbd.H, CH.sub.3, or C.sub.2H.sub.5, and
[0058] L.sup.a, L.sup.b, L.sup.C, and L.sup.d can be the same or
different from each other and each of L.sup.a, L.sup.b, L.sup.C,
and L.sup.d has structure (I) above.
[0059] The iridium dimers can generally be prepared by first
reacting iridium trichloride hydrate with the 2-phenylpyridine,
phenylpyrimidine or phenylquinoline, and adding NaOB.
[0060] One particularly useful iridium dimer is the hydroxo iridium
dimer, having structure VIII below: 8
[0061] This intermediate can be used to prepare compound 1-p by the
addition of ethyl acetoacetate.
[0062] Electronic Device
[0063] The present invention also relates to an electronic device
comprising at least one photoactive layer positioned between two
electrical contact layers, wherein the at least one layer of the
device includes the iridium complex of the invention.
Devicesfrequently have additional hole transport and electron
transport layers. A typical structure is shown in FIG. 1. The
device 100 has an anode layer 110 and a cathode layer 150. Adjacent
to the anode is a layer 120 comprising hole transport material.
Adjacent to the cathode is a layer 140 comprising an electron
transport material. Between the hole transport layer and the
electron transport layer is the photoactive layer 130.
[0064] Depending upon the application of the device 100, the
photoactive layer 130 can be a light-emitting layer that is
activated by an applied voltage (such as in a light-emitting diode
or light-emitting electrochemical cell), a layer of material that
responds to radiant energy and generates a signal with or without
an applied bias voltage (such as in a photodetector). Examples of
photodetectors include photoconductive cells, photoresistors,
photoswitches, phototransistors, and phototubes, and photovoltaic
cells, as these terms are describe in Markus, John, Electronics and
Nucleonics Dictionary, 470 and 476 (McGraw-Hill, Inc. 1966).
[0065] The iridium compounds of the invention are particularly
useful as the photoactive material in layer 130, or as electron
transport material in layer 140. Preferably the iridium complexes
of the invention are used as the light-emitting material in diodes.
It has been found that in these applications, the fluorinated
compounds of the invention do not need to be in a solid matrix
diluent in order to be effective. A layer that is greater than 20%
by weight iridium compound, based on the total weight of the layer,
up to 100% iridium compound, can be used as the emitting layer.
This is in contrast to the non-fluorinated iridium compound,
tris(2-phenylpyridine) iridium (III), which was found to achieve
maximum efficiency when present in an amount of only 6-8% by weight
in the emitting layer. This was necessary to reduce the
self-quenching effect. Additional materials can be present in the
emitting layer with the iridium compound. For example, a
fluorescent dye may be present to alter the color of emission. A
diluent may also be added. The diluent can be a polymeric material,
such as poly(N-vinyl carbazole) and polysilane. It can also be a
small molecule, such as 4,4'-N,N'-dicarbazole biphenyl or tertiary
aromatic amines. When a diluent is used, the iridium compound is
generally present in a small amount, usually less than 20% by
weight, preferably less than 10% by weight, based on the total
weight of the layer.
[0066] In some cases the iridium complexes may be present in more
than one isomeric form, or mixtures of different complexes may be
present. It will be understood that in the above discussion of
OLEDs, the term "the iridium compound" is intended to encompass
mixtures of compounds and/or isomers.
[0067] To achieve a high efficiency LED, the HOMO (highest occupied
molecular orbital) of the hole transport material should align with
the work function of the anode, the LUMO (lowest un-occupied
molecular orbital) of the electron transport material should align
with the work function of the cathode. Chemical compatibility and
sublimation temp of the materials are also important considerations
in selecting the electron and hole transport materials.
[0068] The other layers in the OLED can be made of any materials
which are known to be useful in such layers. The anode 110, is an
electrode that is particularly efficient for injecting positive
charge carriers. It can be made of, for example materials
containing a metal, mixed metal, alloy, metal oxide or mixed-metal
oxide, or it can be a conducting polymer. Suitable metals include
the Group 11 metals, the metals in Groups 4, 5, and 6, and the
Group 8-10 transition metals. If the anode is to be
light-transmitting, mixed-metal oxides of Groups 12, 13 and 14
metals, such as indium-tin-oxide, are generally used. The IUPAC
numbering system is used throughout, where the groups from the
Periodic Table are numbered from left to right as 1-18 (CRC
Handbook of Chemistry and Physics, 81.sup.st Edition, 2000). The
anode 110 may also comprise an organic material such as polyaniline
as described in "Flexible light-emitting diodes made from soluble
conducting polymer," Nature vol. 357, pp 477-479 (June 11, 1992).
At least one of the anode and cathode should be at least partially
transparent to allow the generated light to be observed.
[0069] Examples of hole transport materials for layer 120 have been
summarized for example, in Kirk-Othmer Encyclopedia of Chemical
Technology, Fourth Edition, Vol. 18, p. 837-860, 1996, by Y. Wang.
Both hole transporting molecules and polymers can be used. Commonly
used hole transporting molecules are:
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'--
biphenyl]-4,4'-diamine (TPD), 1,1-bis[(di-4-tolylamino)
phenyl]cyclohexane (TAPC),
N,N'-bis(4-methylphenyl)-N,N'-bis(4-ethylphenyl)-[1,1'-(3,3'-dime-
thyl)biphenyl]-4,4'-diamine (ETPD),
tetrakis-(3-methylphenyl)-N,N,N',N'-2,- 5-phenylenediamine (PDA),
a-phenyl-4-N,N-diphenylaminostyrene (TPS),
p-(diethylamino)-benzaldehyde diphenylhydrazone (DEH),
triphenylamine (TPA),
bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane
(MPMP),
1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyr-
azoline (PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane
(DCZB),
N,N,N',N'-tetrakis(4-methyl-phenyl)-(1,1'-biphenyl)-4,4'-diamine
(TTB), and porphyrinic compounds, such as copper phthalocyanine.
Commonly used hole transporting polymers are polyvinylcarbazole,
(phenylmethyl)polysilane, and polyaniline. It is also possible to
obtain hole transporting polymers by doping hole transporting
molecules such as those mentioned above into polymers such as
polystyrene and polycarbonate.
[0070] Examples of electron transport materials for layer 140
include metal chelated oxinoid compounds, such as
tris(8-hydroxyquinolato)aluminu- m (Alq.sub.3);
phenanthroline-based compounds, such as
2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA) or
4,7-diphenyl-1,10-phenanthroline (DPA), and azole compounds such as
2-(4-biphenylyl)-5-(4-t-butylphenyl)-l,3,4-oxadiazole (PBD) and
3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ).
Layer 140 can function both to facilitate electron transport, and
also serve as a buffer layer or confinement layer to prevent
quenching of the exciton at layer interfaces. Preferably, this
layer promotes electron mobility and reduces exciton quenching.
[0071] The cathode 150, is an electrode that is particularly
efficient for injecting electrons or negative charge carriers. The
cathode can be any metal or nonmetal having a lower work function
than the anode. Materials for the cathode can be selected from
alkali metals of Group 1 (e.g., Li, Cs), the Group 2 (alkaline
earth) metals, the Group 12 metals, including the rare earth
elements and lanthanides, and the actinides. Materials such as
aluminum, indium, calcium, barium, samarium and magnesium, as well
as combinations, can be used. Li-containing organometallic
compounds can also be deposited between the organic layer and the
cathode layer to lower the operating voltage.
[0072] It is known to have other layers in organic electronic
devices. For example, there can be a layer (not shown) between the
conductive polymer layer 120 and the active layer 130 to facilitate
positive charge transport and/or band-gap matching of the layers,
or to function as a protective layer. Similarly, there can be
additional layers (not shown) between the active layer 130 and the
cathode layer 150 to facilitate negative charge transport and/or
band-gap matching between the layers, or to function as a
protective layer. Layers that are known in the art can be used. In
addition, any of the above-described layers can be made of two or
more layers. Alternatively, some or all of inorganic anode layer
110, the conductive polymer layer 120, the active layer 130, and
cathode layer 150, may be surface treated to increase charge
carrier transport efficiency. The choice of materials for each of
the component layers is preferably determined by balancing the
goals of providing a device with high device efficiency.
[0073] It is understood that each functional layer may be made up
of more than one layer.
[0074] The device can be prepared by sequentially vapor depositing
the individual layers on a suitable substrate. Substrates such as
glass and polymeric films can be used. Conventional vapor
deposition techniques can be used, such as thermal evaporation,
chemical vapor deposition, and the like. Alternatively, the organic
layers can be coated from solutions or dispersions in suitable
solvents, using any conventional coating technique. In general, the
different layers will have the following range of thicknesses:
anode 110, 500-5000 .ANG., preferably 1000-2000 .ANG.; hole
transport layer 120, 50-1000 .ANG., preferably 200-800 .ANG.;
light-emitting layer 130, 10-1000 .ANG., preferably 100-800 .ANG.;
electron transport layer 140, 50-1000 .ANG., preferably 200-800
.ANG.; cathode 150, 200-10000 .ANG., preferably 300-5000 .ANG.. The
location of the electron-hole recombination zone in the device, and
thus the emission spectrum of the device, can be affected by the
relative thickness of each layer. Thus the thickness of the
electron-transport layer should be chosen so that the electron-hole
recombination zone is in the light-emitting layer. The desired
ratio of layer thicknesses will depend on the exact nature of the
materials used.
[0075] It is understood that the efficiency of devices made with
the iridium compounds of the invention, can be further improved by
optimizing the other layers in the device. For example, more
efficient cathodes such as Ca, Ba or LiF can be used. Shaped
substrates and novel hole transport materials that result in a
reduction in operating voltage or increase quantum efficiency are
also applicable. Additional layers can also be added to tailor the
energy levels of the various layers and facilitate
electroluminescence.
[0076] The iridium complexes of the invention often are
phosphorescent and photoluminescent and may be useful in
applications other than OLEDs. For example, organometallic
complexes of iridium have been used as oxygen sensitive indicators,
as phosphorescent indicators in bioassays, and as catalysts. The
bis cyclometalated complexes can be used to sythesize tris
cyclometalated complexes where the third ligand is the same or
different.
EXAMPLES
[0077] The following examples illustrate certain features and
advantages of the present invention. They are intended to be
illustrative of the invention, but not limiting. All percentages
are by weight, unless otherwise indicated.
Example 1
[0078] This example illustrates the preparation of the
2-phenylpyridines and 2-phenylpyrimidines which are used to form
the iridium compounds.
[0079] The general procedure used was described in O. Lohse, P.
Thevenin, E. Waldvogel Synlett, 1999, 45-48. In a typical
experiment, a mixture of 200 ml of degassed water, 20 g of
potassium carbonate, 150 ml of 1,2-dimethoxyethane, 0.5 g of
Pd(PPh.sub.3).sub.4, 0.05 mol of a substituted 2-chloropyridine
(quinoline or pyrimidine) and 0.05 mol of a substituted
phenylboronic acid was refluxed (80-90.degree. C.) for 16-30 h. The
resulting reaction mixture was diluted with 300 ml of water and
extracted with CH.sub.2Cl.sub.2 (2.times.100 ml). The combined
organic layers were dried over MgSO.sub.4, and the solvent removed
by vacuum. The liquid products were purified by fractional vacuum
distillation. The solid materials were recrystallized from hexane.
The typical purity of isolated materials was >98%.
[0080] The starting materials, yields, melting and boiling points
of the new materials are given in Table 3. NMR data and analytical
data are given in Table 4.
3TABLE 3 Preparation of 2-Phenyl Pyridines, Phenylpyrimidines and
Phenylquinolines Compound Yield in % B.p./mm Hg (m.p.) in .degree.
C. .sup. 2-s 70 -- .sup. 2-a 72 -- 2-b 48 -- 2-u 75 (76-78) .sup.
2-c 41 (95-96) 2-d 38 (39-40) .sup. 2-e 55 74.5/0.1 2-g 86
71-73/0.07 2-t 65 77-78/0.046 2-k 50 (38-40) 2-m 80 72-73/0.01
2-f.sup. 22 52-33/0.12 2-v 63 95-96/13 2-w 72 2-x 35 61-62/0.095
2-y 62 (68-70) .sup. 2-z 42 66-67/0.06 (58-60) .sup. 2-aa 60
[0081]
4TABLE 4 Properties of 2-Phenyl Pyridines, Phenylpyrimidines and
Phenylquinolines Analysis %, found (calc.) Compound .sup.1H NMR
.sup.19F NMR or MS (M.sup.+) .sup. 2-s 7.48 (3H), -62.68 C, 64.50
7.70 (1H), (64.57) 7.83 (1H), H, 3.49 7.90 (2H), (3.59) 8.75 (1H)
N, 6.07 (6.28) .sup. 2-a 7.19 (1H), -60.82 (3F, s), C, 59.56 7.30
(1H), -116.96 (1F, m) (59.75) 7.43 (1H), H, 3.19 7.98 (2H), (2.90)
8.07 (1H) N, 5.52 9.00 (1H) (5.81) 2-b 7.58 (1H), -62.75 (3F, s),
C, 53.68 7.66 (1H), -63.10 (3F, s) (53.60) 7.88 (1H), H, 2.61 8.03
(1H), (2.40) 8.23 (1H), N, 4.53 8.35 (1H) (4.81) 8.99 (1H) 2-u 7.55
(1H), -62.89 (s) C, 69.17 7.63 (1H), (70.33) 7.75 (2H), H, 3.79
7.89 (2H), (3.66) 8.28 (2H), N, 4.88 8.38 (1H), (5.12) 8.50 (1H)
.sup. 2-c 7.53 (1H), -62.14 (s) C, 53.83 (53.73) 7.64 (1H), H, 2.89
7.90 (1H), (2.61) 8.18 (1H), N, 9.99 8.30 (1H), (10.44) 8.53 (1H),
9.43 (1H) 2-d 7.06 (1H), -62.78 (3F, s), C, 59.73 7.48 (1H),
-112.61 (59.75) 7.81 (3H), H, 2.86 8.01 (1H), (1F, m) (2.90) 8.95
(1H), N, 5.70 (5.81) .sup. 2-e 3.80 (3H) -62.63 C, 61.66 6.93 (2H),
(s) (61.90) 7.68 (1H), H, 3.95 7.85 (1H), (4.04) 7.96 (2H), N, 5.53
8.82 (1H), (5.38) 2-g 2.70 (3H) -114.03 C, 76.56 7.10 (3H), (m)
(77.00) 7.48 (1H), H, 5.12 7.60 (1H), (5.30) 8.05 (2H), N, 5.43
(7.50) 2-t 7.10 (2H), -62.73 C, 50.51 7.35 (2H), (3F, s) (52.17)
7.96 (1H), -113.67 H, 1.97 8.78 (1H), (1F, m) (2.17) N, 5.09 (5.07)
2-k 7.08 (2H), -62.75 C, 60.39 7.62 (1H), (3F, s) (59.75), H, 3.38
7.90 (3H), -111.49 (2.90), 8.80 (1H), (m) N, 5.53 (5.51) 2-m 7.10
(2H), -62.63 C, 52.13 7.80 (2H), (3F, s) (52.17) 8.00 (1H), -111.24
H, 2.16 8.75 (1H), (m) (2.17) N, 4.85 (5.07) 2-f.sup. 7.55 (3H),
-62.57 (s) 257 (M.sup.+, 7.77 (2H),
C.sub.l2H.sub.7F.sub.3ClN.sup.+), 8.06 (1H), 222 (M-Cl) 8.87 (1H)
2-v 3.8 (3H), -62.70 ppm C, 61.66 (61.37), 6.95 (1H), H, 3.98
(3.67), 7.30 (1H), N, 5.53 (5.48) 7.50 (1H), 7.58 (1H), 7.75 (1H),
7.90 (1H), 8.87 (1H) 2-w 8.54 (1H, d),.sup. -63.08 (3F, s) 8.21
(2H, d),.sup. 7.70 (2H, d),.sup. 7.24 (1H, s), 6.82 (1H, dd), .sup.
3.91 (3H, s) 2-x 6.9 (2H, m), -109.70 (1F, m), 7.18 (2H, m),.sup.
-113.35 (1F, m). 7.68 (2H, m),.sup. 7.95 (1H, m),.sup. 8.65 (1H,
m);.sup. 2-y 6.94 (1H), -62.72 ( 3F, s), 7.62 (2H), -109.11 (2F, m)
7.82 (1H), 8.03 (1H), 8.96 (1H); .sup. 2-z 6.85 (1H), -62.80 (3F,
s), 6.93 (1H), -107.65 (1F, m), 7.80, 7.90, -112.45 (1F, m). 8.05
(3H), 8.89 (1H); .sup. 2-aa 7.70 (3H, m),.sup. 7.85 (3H, m),.sup.
7.80, 7.90, 8.85 (1H, m)..sup.
Example 2
[0082] This example illustrates the preparation of iridium
compounds of the Fourth Formula fac-Ir(L.sup.a).sub.3 above.
[0083] In a typical experiment, a mixture of
IrCl.sub.3..multidot.nH.sub.2- O (53-55% Ir), AgOCOCF.sub.3 (3.1
equivalents per Ir), 2-arylpyridine (excess), and (optionally) a
small amount of water was vigorously stirred under N.sub.2 at
180-195.degree. C. (oil bath) for 2-8 hours. The resulting mixture
was thoroughly extracted with CH.sub.2Cl.sub.2 until the extracts
were colorless. The extracts were filtered through a silica column
to produce a clear yellow solution. Evaporation of this solution
gave a residue which was treated with methanol to produce colored
crystalline tris-cyclometalated Ir complexes. The complexes were
separated by filtration, washed with methanol, dried under vacuum,
and (optionally) purified by crystallization, vacuum sublimation,
or Soxhlet extraction. Yields: 10-82%. All materials were
characterized by NMR spectroscopic data and elemental analysis, and
the results are given in Table 5 below. Single-crystal X-ray
structures were obtained for three complexes of the series.
[0084] Compound 1-b
[0085] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 508
mg), 2-(4-fluorophenyl)-5-trifluoromethylpyridine, compound kk
(2.20 g), AgOCOCF.sub.3 (1.01 g), and water (1 mL) was vigorously
stirred under a flow of N.sub.2 as the temperature was slowly (30
min) brought up to 185.degree. C. (oil bath). After 2 hours at
185-190.degree. C. the mixture solidified. The mixture was cooled
down to room temperature. The solids were extracted with
dichloromethane until the extracts decolorized. The combined
dichloromethane solutions were filtered through a short silica
column and evaporated. After methanol (50 mL) was added to the
residue the flask was kept at -10.degree. C. overnight. The yellow
precipitate of the tris-cyclometalated complex, compound b, was
separated, washed with methanol, and dried under vacuum. Yield:
1.07 g (82%). X-Ray quality crystals of the complex were obtained
by slowly cooling its warm solution in 1,2-dichloroethane.
[0086] Compound 1-e
[0087] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 504
mg), 2-(3-trifluoromethylphenyl)-5-trifluoromethylpyridine,
compound bb (1.60 g), and AgOCOCF.sub.3 (1.01 g) was vigorously
stirred under a flow of N.sub.2 as the temperature was slowly (15
min) brought up to 192.degree. C. (oil bath). After 6 hours at
190-195.degree. C. the mixture solidified. The mixture was cooled
down to room temperature. The solids were placed on a silica column
which was then washed with a large quantity of dichloromethane. The
residue after evaporation of the filtrate was treated with methanol
to produce yellow solid. The solid was collected and purified by
extraction with dichloromethane in a 25-mL micro-Soxhlet extractor.
The yellow precipitate of the tris-cyclometalated complex, compound
e, was separated, washed with methanol, and dried under vacuum.
Yield: 0.59 g (39%). X-Ray quality crystals of the complex were
obtained from hot 1,2-dichloroethane.
[0088] Compound 1-d
[0089] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 508
mg), 2-(2-fluorophenyl)-5-trifluoromethylpyridine, compound aa
(1.53 g), and AgOCOCF.sub.3 (1.01 g) was vigorously stirred under a
flow of N.sub.2 at 190-195.degree. C. (oil bath) for 6 h 15 min.
The mixture was cooled down to room temperature and then extracted
with hot 1,2-dichloroethane. The extracts were filtered through a
short silica column and evaporated. Treatment of the residue with
methanol (20 mL) resulted in precipitation of the desired product,
compound d, which was separated by filtration, washed with
methanol, and dried under vacuum. Yield: 0.63 g (49%). X-Ray
quality crystals of the complex were obtained from
dichloromethane/methanol.
[0090] Compound 1-i
[0091] A mixture of IrCl.sub.3.multidot.nH.sub.2O (54% Ir; 503 mg),
2-(4-trifluoromethoxyphenyl)-5-trifluoromethylpyridine, compound ee
(2.00 g), and AgOCOCF.sub.3 (1.10 g) was vigorously stirred under a
flow of N.sub.2 at 190-195.degree. C. (oil bath) for 2 h 45 min.
The mixture was cooled down to room temperature and then extracted
with dichloromethane. The extracts were filtered through a short
silica column and evaporated. Treatment of the residue with
methanol (20 mL) resulted in precipitation of the desired product,
compound i, which was separated by filtration, washed with
methanol, and dried under vacuum. The yield was 0.86 g.
Additionally, 0.27 g of the complex was obtained by evaporating the
mother liquor and adding petroleum ether to the residue. Overall
yield: 1.13 g (72%).
[0092] Compound 1-q
[0093] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 530
mg), 2-(3-methoxyphenyl)-5-trifluoromethylpyridine (2.50 g),
AgOCOCF.sub.3 (1.12 g), and water (1 mL) was vigorously stirred
under a flow of N.sub.2 as the temperature was slowly (30 min)
brought up to 185.degree. C. (oil bath). After 1 hour at
185.degree. C. the mixture solidified. The mixture was cooled down
to room temperature. The solids were extracted with dichloromethane
until the extracts decolorized. The combined dichloromethane
solutions were filtered through a short silica column and
evaporated. The residue was washed with hexanes and then
recrystallized from 1,2-dichloroethane-hexanes (twice). Yield: 0.30
g. .sup.19F NMR (CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: -63
(s). .sup.1H NMR (CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: 8.1
(1H), 7.9 (1H), 7.8 (1H), 7.4(1H), 6.6 (2H), 4.8 (3H). X-Ray
quality crystals of the complex (1,2-dichloroethane, hexane
solvate) were obtained from 1,2-dichloroethane-hexanes. This facial
complex was orange-photoluminescent.
[0094] Compounds 1-a, 1-c, 1-f through 1-h, 1-j through 1-m and 1-r
were similarly prepared. In the preparation of compound 1-j, a
mixture of isomers was obtained with the fluorine in either the
R.sub.6 or R.sub.8 position.
5TABLE 5 Analysis NMR Compound (calcd (found) (CD.sub.2Cl.sub.2,
25.degree. C.) .sup. 1-a C: 50.3 (50.1) .sup.1H: 6.8 (1H), 6.9
(1H), 7.0 (1H), 7.8 H: 2.5 (2.7) (2H), 7.95 (1H), 8.1 (1H) N: 4.9
(4.9) .sup.19F: -63.4 Cl: 0.0 (0.2) 1-b C: 47.4 (47.3) .sup.1H: 6.4
(1H), 6.75 (1H), 7.7 (1H), 7.8 H: 2.0 (2.1) (1H), 7.95 (1H), 8.05
(1H) N: 4.6 (4.4) .sup.19F: -63.4 (s); -109.5 (ddd) .sup. 1-c C:
47.4 (47.2) .sup.1H: 6.6 (1H), 6.7 (1H), 6.9 (1H), 7.8 H: 2.0 (2.0)
(1H), 8.0 (1H), 8.6 (1H) N: 4.6 (4.5) .sup.19F: -63.5 (s); -112.8
(ddd) 1-d C: 55.9 (56.1) .sup.1H: 6.6 (2H), 6.8 (1H), 7.0 (1H), 7.6
H: 3.0 (3.2) (1H), 7.7 (1H), 8.4 (1H) N: 5.9 (5.8) .sup.19F: -115.0
(ddd) .sup. 1-e C: 44.1 (43.3) .sup.1H: 6.9 (1H), 7.1 (1H), 7.8
(1H), 8.0 H: 1.7 (2.1) (2H), 8.2 (1H) N: 3.9 (3.6) .sup.19F: -63.0
(1F), -63.4 (1F) 1-f.sup. C: 50.4 (50.5) .sup.1H: 6.9 (1H), 7.1
(2H), 7.6 (1H), 7.8 H: 2.5 (2.7) (1H), 7.9 (1H), 8.1 (1H) N: 4.9
(4.9) .sup.19F: -62.4 1-g C: 55.9 (56.3) .sup.1H; 6.4 (1H), 6.7
(1H), 7.0 (1H), 7.6 H: 3.0 (3.2) (1H), 7.7 (2H), 7.9 (1H) N: 5.9
(6.0) .sup.19F: -112.6 (ddd) 1-h C: 51.0 (45.2) .sup.1H: 6.8 (1H),
6.95 (1H), 7.05 (1H), 7.7 H: 2.1 (2.3) (1H), 8.0 (1H), 8.9 (1H) N:
4.9 (4.2) .sup.19F: -63.3 1-i C: 49.4 (49.3) .sup.1H: 3.6 (3H), 6.3
(1H), 6.6 (1H), 7.7 H: 2.9 (2.8) (2H), 7.85 (1H), 7.95 (1H) N: 4.4
(4.4) .sup.19F: -63.2 1-j C: 47.4 (47.4) .sup.1H: 6.7 (m), 7.1 (m),
7.5 (m), 7.6 (m), H: 2.0 (2.3) 7.7 (m), 8.0 (m), 8.2 (m) N: 4.6
(4.7) .sup.19F: 8 s resonances (-63.0--63.6) and 8 ddd resonances
(-92.2--125.5) 1-k C: 43.5 (44.0) .sup.1H: 6.9 (1H), 7.15 (1H), 8.1
(1H), 8.3 H: 1.8 (2.1) (1H), 8.45 (1H), 8.6 (1H) N: 8.5 (8.4)
.sup.19F: -62.9 1-l C: 42.2 (42.1) .sup.1H: 6.5 (1H), 6.7 (1H),
7.75 (1H), 7.85 H: 16. (1.8) (1H), 8.0 (1H), 8.1 (1H) N: 3.8 (3.7)
.sup.19F: -58.1 (1F), -63.4 (1F)
Example 3
[0095] This example illustrates the preparation of iridium
complexes of the Second Formula
IrL.sup.aL.sup.bL.sup.c.sub.xL'.sub.yL".sub.z above,
[0096] Compound 1-n
[0097] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 510
mg), 2-(3-trifluoromethylphenyl)-quinoline (1.80 g), and silver
trifluoroacetate (1.10 g) was vigorously stirred at 190-195.degree.
C. for 4 hours. The resulting solid was chromatographed on silica
with dichloromethane to produce a mixture of the dicyclometalated
complex and the unreacted ligand. The latter was removed from the
mixture by extraction with warm hexanes. After the extracts became
colorless the hexane-insoluble solid was collected and dried under
vacuum. The yield was 0.29 g. .sup.19F NMR: -63.5 (s, 6F), -76.5
(s, 3F). The structure of this complex was established by a single
crystal X ray diffraction study.
[0098] Compound 1-o
[0099] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 500
mg), 2-(2-fluorophenyl)-3-chloro-5-trifluoromethylpyridine (2.22
g), water (0.3 mL), and silver trifluoroacetate (1.00 g) was
stirred at 190.degree. C. for 1.5 hours. The solid product was
chromatographed on silica with dichloromethane to produce 0.33 g of
a 2:1 co-crystallized adduct of the dicyclometalated aqua
trifluoroacetato complex, compound 1-p, and the unreacted ligand.
.sup.19F NMR: -63.0 (9F), -76.5 (3F), -87.7 (2F), -114.4 (1F). The
co-crystallized phenylpyridine ligand was removed by
recrystallization from dichloromethane-hexanes. The structures of
both the adduct and the complex were established by a single
crystal X-ray diffraction study.
Example 4
[0100] This example illustrates the preparation of an hydroxo
iridium dimer, having structure (VIII) above.
[0101] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 510
mg), 2-(4-fluorophenyl)-5-trifluoromethylpyridine (725 mg), water
(5 mL), and 2-ethoxyethanol (20 mL) was vigorously stirred under
reflux for 4.5 hours. After a solution of NaOH (2.3 g) in water (5
mL) was added, followed by 20 mL of water, the mixture was stirred
under reflux for 2 hours. The mixture was cooled down to room
temperature, diluted with 50 mL of water, and filtered. The solid
was vigorously stirred under reflux with 30 mL of
1,2-dichloroethane and aqueous NaOH (2.2 g in 8 mL of water) for 6
hours. The organic solvent was evaporated from the mixture to leave
a suspension of an orange solid in the aqueous phase. The orange
solid was separated by filtration, thoroughly washed with water,
and dried under vacuum to produce 0.94 g (95%) of the iridium
hydroxo dimer (spectroscopically pure). .sup.1H NMR
(CD.sub.2Cl.sub.2): -1.0 (s, 1H, IrOH), 5.5 (dd, 2H), 6.6 (dt, 2H),
7.7 (dd, 2H), 7.9 (dd, 2H), 8.0 (d, 2H), 9.1 (d, 2H). .sup.19F NMR
(CD.sub.2Cl.sub.2): -62.5 (s, 3F), -109.0 (ddd, 1F).
Example 5
[0102] This example illustrates the preparation of
bis-cyclometalated complexes from an iridium dimer.
[0103] Compound 1-p
[0104] A mixture of the iridium hydroxo dimer (100 mg) from Example
4, ethyl acetoacetate (0.075 mL; 4-fold excess), and
dichloromethane (4 mL) was stirred at room temperature overnight.
The solution was filtered through a short silica plug and
evaporated to give an orange-yellow solid which was washed with
hexanes and dried. The yield of the complex was 109 mg (94%).
.sup.1H NMR (CD.sub.2Cl.sub.2): 1.1 (t, CH.sub.3), 3.9 (dm,
CH.sub.2), 4.8 (s, CH.sub.3COCH), 5.9 (m), 6.7 (m), 7.7 (m), 8.0
(m), 8.8 (d). .sup.19F NMR (CD.sub.2Cl.sub.2): -63.1 (s, 3F), -63.2
(s, 3F), -109.1 (ddd, 1F), -109.5 (ddd). Analysis: Calcd: C, 44.9;
H, 2.6; N, 3.5. Found: C, 44.4; H, 2.6; N, 3.3.
[0105] Compound 1-w
[0106] A solution of hydroxo iridium dimer from Example 4 (0.20 g)
in THF (6 mL) was treated with 50 mg of trifluoroacetic acid,
filtered through a short silica plug, evaporated to ca. 0.5 mL,
treated with hexanes (8 mL), and left overnight. The yellow
crystalline solid was separated, washed with hexanes, and dried
under vacuum. Yield (1:1 THF solvate): 0.24 g (96%). .sup.19F NMR
(CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: -63.2 (s, 3F), -76.4
(s, 3F), -107.3 (ddd, 1F). .sup.1H NMR (CD.sub.2Cl.sub.2,
20.degree. C.), .delta.: 9.2 (br s, 1H), 8.2 (dd, 1H), 8.1 (d, 1H),
7.7 (m, 1H), 6.7 (m, 1H), 5.8 (dd, 1H), 3.7 (m, 2H, THF), 1.8 (m,
2H, THF).
[0107] Compound 1-x
[0108] A mixture of the trifluoroacetate intermediate, compound 1-w
(75 mg), and 2-(4-bromophenyl)-5-bromopyridine (130 mg) was stirred
under N.sub.2 at 150-155.degree. C. for 30 min. The resulting solid
was cooled to room temperature and dissolved in CH.sub.2Cl.sub.2.
The resulting solution was filtered through silica gel and
evaporated. The residue was washed several times with warm hexanes
and dried under vacuum to leave a yellow, yellow-photoluminescent
solid. Yield: 74 mg (86%). .sup.19F NMR (CD.sub.2Cl.sub.2,
20.degree. C.), .delta.: -63.1 (s, 3F), -63.3 (s, 3F), -108.8 (ddd,
1F), -109.1 (ddd, 1F). .sup.1H NMR (CD.sub.2Cl.sub.2, 20.degree.
C.), .delta.: 8.2 (s), 7.9 (m), 7.7 (m), 7.0 (m), (d), 6.7 (m), 6.2
(dd), 6.0 (dd). The complex was meridional, with the nitrogens of
the fluorinated ligands being trans, as confirmed by X-ray
analysis.
Example 6
[0109] This example illustrates the preparation of iridium
compounds of the Fifth Formula mer-Ir(L.sup.a).sub.3 above.
[0110] Compound 1-s
[0111] This complex was synthesized in a manner similar to compound
1-n. According to the NMR, TLC, and TGA data, the result was an
approximately 1:1 mixture of the facial and meridional isomers.
[0112] Compound 1-t
[0113] A mixture of IrCl.sub.3..multidot.nH.sub.2O (54% Ir; 0.40
g), 2-(3,5-difluorophenyl)-5-trifluoromethylpyridine (1.40 g),
AgOCOCF.sub.3 (0.81 g), and water (0.5 mL) was vigorously stirred
under a flow of N.sub.2 as the temperature was slowly (30-40 min)
brought up to 165.degree. C. (oil bath). After 40 min at
165.degree. C. the mixture solidified. The mixture was cooled down
to room temperature. The solids were extracted with dichloromethane
until the extracts decolorized. The combined dichloromethane
solutions were filtered through a short silica column and
evaporated. The residue was thoroughly washed with hexanes and
dried under vacuum. Yield: 0.53 g (49%). .sup.19F NMR
(CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: -63.55 (s, 3F), -63.57
(s, 3F), -63.67 (s, 3F), -89.1 (t, 1F), -100.6 (t, 1F), -102.8 (dd,
1F), -118.6 (ddd, 1F), -119.3 (ddd, 1F), -123.3 (ddd, 1F). .sup.1H
NMR (CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: 8.4 (s), 8.1 (m),
7.9 (m), 7.6 (s), 7.5 (m), 6.6 (m), 6.4 (m). The complex was
meridional, as was also confirmed by X-ray analysis.
[0114] Compound 1-u
[0115] This complex was prepared and isolated similarly to compound
1-q, then purified by crystallization from
1,2-dichloroethane-hexanes. The yield of the purified product was
53%. The complex is mer, as follows from the NMR data. .sup.19F NMR
(CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: -63.48 (s, 3F), -63.52
(s, 6F), -105.5 (ddd, 1F) -105.9 (ddd, 1F), -106.1 (ddd, 1F),
-107.4 (t, 1F), -107.9 (t, 1F), -109.3 (t, 1F). .sup.1H NMR
(CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: 8.6 (m), 8.3 (s), 8.2
(s), 8.1 (m), 7.9 (m), 7.6 (m), 6.6 (m), 6.4 (m), 6.0 (m), 5.8
(m).
[0116] Compound 1-v
[0117] This mer-complex was prepared in a manner similar to
compound 1-w, using the trifluoroacetate dicyclometalated
intermediate, compound 1-x, and
2-(4-fluorophenyl)-5-trifluoromethylpyridine. .sup.19F NMR
(CD.sub.2Cl.sub.2, 20.degree. C.), .delta.: -63.30 (s, 3F), -63.34
(s, 3F), -63.37 (s, 3F), -108.9 (ddd, 1F), -109.0 (ddd, 1F), -109.7
(ddd, 1F). .sup.1H NMR (CD.sub.2Cl.sub.2, 20.degree. C.), .delta.:
8.3-7.6 (m), 6.7 (m), 6.6 (dd), 6.3 (dd), 6.0 (dd). This
yellow-luminescent merisional complex isomerised to the green
luminescent facial isomer, compound 1-b, upon sublimation at 1
atm.
Example 7
[0118] This example illustrates the formation of OLEDs using the
iridium complexes of the invention.
[0119] Thin film OLED devices including a hole transport layer (HT
layer), electroluminescent layer (EL layer) and at least one
electron transport layer (ET layer) were fabricated by the thermal
evaporation technique. An Edward Auto 306 evaporator with oil
diffusion pump was used. The base vacuum for all of the thin film
deposition was in the range of 10.sup.-6 torr. The deposition
chamber was capable of depositing five different films without the
need to break up the vacuum.
[0120] An indium tin oxide (ITO) coated glass substrate was used,
having an ITO layer of about 1000-2000 .ANG.. The substrate was
first patterned by etching away the unwanted ITO area with 1N HCl
solution, to form a first electrode pattern. Polyimide tape was
used as the mask. The patterned ITO substrates were then cleaned
ultrasonically in aqueous detergent solution. The substrates were
then rinsed with distilled water, followed by isopropanol, and then
degreased in toluene vapor for .about.3 hours.
[0121] The cleaned, patterned ITO substrate was then loaded into
the vacuum chamber and the chamber was pumped down to 10.sup.-6
torr. The substrate was then further cleaned using an oxygen plasma
for about 5-10 minutes. After cleaning, multiple layers of thin
films were then deposited sequentially onto the substrate by
thermal evaporation. Finally, patterned metal electrodes of Al were
deposited through a mask. The thickness of the film was measured
during deposition using a quartz crystal monitor (Sycon STC-200).
All film thickness reported in the Examples are nominal, calculated
assuming the density of the material deposited to be one. The
completed OLED device was then taken out of the vacuum chamber and
characterized immediately without encapsulation.
[0122] A summary of the device layers and thicknesses is given in
Table 6. In all cases the anode was ITO as discussed above, and the
cathode was Al having a thickness in the range of 700-760 .ANG.. In
some of the samples, a two-layer electron transport layer was used.
The layer indicated first was applied adjacent to the EL layer.
6TABLE 6 HT layer EL layer ET layer Sample (Thickness, .ANG.)
(Thickness, .ANG.) (Thickness, .ANG.) Compar- MPMP (528)
Ir(ppy).sub.3 (408) DDPA (106) + Alq.sub.3 (320) ative 1 MPMP (520)
Compound 1-b DDPA (125) + Alq.sub.3 (365) (499) 2 MPMP (541)
Compound 1-b DDPA (407) (580) 3 MPMP (540) Compound 1-e DDPA (112)
+ Alq.sub.3 (340) (499) 4 MPMP (525) Compound 1-k DDPA (106)
Alq.sub.3 (341) (406) 5 MPMP (570) Compound 1-i DDPA (107) +
Alq.sub.3 (339) (441) 6 MPMP (545) Compound 1-j DDPA (111) +
Alq.sub.3 (319) (462) 7 MPMP (643) Compound 1-g DDPA (112) +
Alq.sub.3 (361) (409) 8 MPMP (539) Compound 1-f DDPA (109) +
Alq.sub.3 (318) (430) 9 MPMP (547) Compound 1-a DDPA (105) +
Alq.sub.3 (300) (412) 10 MPMP (532) Compound 1-h DDPA (108) +
Alq.sub.3 (306) (457) 11 MPMP (603) Compound 1-d DDPA (111) +
Alq.sub.3 (303) (415) 12 MPMP (551) Compound 1-c DDPA (106) +
Alq.sub.3 (313) (465) 13 MPMP (520) Compound 1-l DDPA (410) (405)
14 MPMP (504) Compound 1-b DDPA (393) (400) 15 MPMP (518) Compound
1-b DDPA (418) (153) 16 MPMP (556) Compound 1-m DDPA (430) (416) 17
MPMP (520) Compound 1-n DDPA (420) (419) 18 MPMP (511) Compound 1-o
DDPA (413) (412) 19 MPMP (527) Compound 1-p DDPA (412) (425) 20
MPMP (504) Compound 1-q DPA (407) (417) 21 MPMP Compound 1-t DPA
(416) (525) (419) 22 MPMP Compound 1-u DPA (405) (520) (421)
Alq.sub.3 = tris(8-hydroxyquinolato) aluminum DDPA =
2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline Ir(ppy).sub.3 =
fac-tris(2-phenylpyridine) iridium MPMP = bis[4-(N,N-diethylamino-
)-2-methylphenyl](4-methylphenyl)methane
[0123] The OLED samples were characterized by measuring their (1)
current-voltage (I-V) curves, (2) electroluminescence radiance
versus voltage, and (3) electroluminescence spectra versus voltage.
The apparatus used, 200, is shown in FIG. 2. The I-V curves of an
OLED sample, 220, were measured with a Keithley Source-Measurement
Unit Model 237, 280. The electroluminescence radiance (in the unit
of Cd/m.sup.2) vs. voltage was measured with a Minolta LS-110
luminescence meter, 210, while the voltage was scanned using the
Keithley SMU. The electroluminescence spectrum was obtained by
collecting light using a pair of lenses 230, through an electronic
shutter, 240, dispersed through a spectrograph, 250, and then
measured with a diode array detector, 260. All three measurements
were performed at the same time and controlled by a computer, 270.
The efficiency of the device at certain voltage is determined by
dividing the electroluminescence radiance of the LED by the current
density needed to run the device. The unit is in Cd/A.
[0124] The result are given in Table 7 below:
7TABLE 7 Electroluminescent Properties of Iridium Compounds
Approximate Peak Efficiency at Peak Peak Radiance, peak radiance,
efficiency, Wavelengths, Sample Cd/m2 Cd/A Cd/A nm Comparative 540
0.39 0.48 522 at 22 V 1 1400 3.4 11 525 at 21 V 2 1900 5.9 13 525
at 25 V 3 830 1.7 13.5 525 at 18 V 4 7.6 0.005 0.13 521 at 27 V 5
175 0.27 1.8 530, 563 at 25 V 6 514 1.5 2.2 560 at 20 V 7 800 0.57
1.9 514 at 26 V 8 1200 0.61 2 517 at 28 V 9 400 1.1 4 545 at 18 V
10 190 2.3 3.3 575 at 16 V 11 1150 1.2 3.8 506, 526 at 25 V 12 340
0.49 2.1 525 at 20 V 13 400 3 5 520 at 21 V 14 1900 5 9 525 15 2500
6 11 525 16 100 0.17 0.2 560 at 27 V 17 3.5 0.005 0.014 575 at 28 V
18 30 0.08 0.16 590 at 26 V 19 2000 6 8 532 at 21 V 20 350 0.60 1.6
595 at 26 V 21 1200 5 545 at 22 V 22 80 1 540 at 19 V
[0125] The peak efficiency is the best indication of the value of
the electroluminescent compound in a device. It gives a measure of
how many electrons have to be input into a device in order to get a
certain number of photons out radience). It is a fundamentally
important number, which reflects the intrinsic efficiency of the
light-emitting material. It is also important for practical
applications, since higher efficiency means that fewer electrons
are needed in order to achieve the same radiance, which in turn
means lower power consumption. Higher efficiency devices also tend
to have longer lifetimes, since a higher portion of injected
electrons are converted to photons, instead of generating heat or
causing an undesirable chemical side reactions. Most of the iridium
complexes of the invention have much higher peak efficiencies than
the parent fac-tris(2-phenylpyridine) iridium complex. Those
complexes with lower efficiencies may also find utility as
phosphorescent or photoluminescent materials, or as catalysts, as
discussed above.
* * * * *