U.S. patent application number 10/774286 was filed with the patent office on 2007-12-20 for electroluminescent iridium compounds with fluorinated phenylpyridine ligands, and devices made with such compounds.
Invention is credited to Kerwin D. Dobbs, Norman Herron, Viacheslav A. Petrov.
Application Number | 20070292713 10/774286 |
Document ID | / |
Family ID | 34841270 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070292713 |
Kind Code |
A9 |
Dobbs; Kerwin D. ; et
al. |
December 20, 2007 |
Electroluminescent iridium compounds with fluorinated
phenylpyridine ligands, and devices made with such compounds
Abstract
The present invention is generally directed to
electroluminescent Ir(III) compounds, the substituted
2-phenylpyridines that are used to make the Ir(III) compounds, and
devices that are made with the Ir(III) compounds.
Inventors: |
Dobbs; Kerwin D.;
(Wilmington, DE) ; Herron; Norman; (Newark,
DE) ; Petrov; Viacheslav A.; (Hockessin, 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
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Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20050037233 A1 |
February 17, 2005 |
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Family ID: |
34841270 |
Appl. No.: |
10/774286 |
Filed: |
February 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10768298 |
Jan 30, 2004 |
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10774286 |
Feb 6, 2004 |
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10366295 |
Feb 13, 2003 |
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10774286 |
Feb 6, 2004 |
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09879014 |
Jun 12, 2001 |
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10366295 |
Feb 13, 2003 |
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60215362 |
Jun 30, 2000 |
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60224273 |
Aug 10, 2000 |
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Current U.S.
Class: |
428/690 ; 257/40;
313/504; 428/917; 546/4 |
Current CPC
Class: |
C09K 2211/1029 20130101;
H01L 51/0085 20130101; H01L 51/5016 20130101; C09K 11/06 20130101;
C09K 2211/185 20130101; Y10S 428/917 20130101 |
Class at
Publication: |
428/690 ;
428/917; 313/504; 257/040; 546/004 |
International
Class: |
H05B 33/14 20060101
H05B033/14; C09K 11/06 20060101 C09K011/06 |
Claims
1. An organic electronic device comprising at least one layer
comprising a compound having Formula I ##STR15## wherein:
R.sup.1=H, R.sup.4, OR.sup.4, N(R.sup.4).sub.2 R.sup.2=H,
C.sub.nF.sub.2n+1, C.sub.nF.sub.2n+1SO.sub.2, COOR.sup.4, CN
R.sup.3=H, C.sub.nF.sub.2n+1, C.sub.nF.sub.2n+1SO.sub.2,
COOR.sup.4, CN R.sup.4 is the same or different at each occurrence
and is H, alkyl, aryl, or adjacent R.sup.4 groups can join together
to form a 5- or 6-membered ring, L'=a bidentate ligand and is not a
phenylpyridine, phenylpyrimidine, or phenylquinoline; L''=a
monodentate ligand, and is not a phenylpyridine, and
phenylpyrimidine, or phenylquinoline; m=1, 2 or 3, n is an integer
from 1 through 20, y=0, 1 or 2, and z=0 or an integer from 1
through 4, with the proviso that the compound is charge neutral and
the iridium is hexacoordinate.
2. The device of claim 1 wherein R.sup.2 and R.sup.3 are
independently selected from H, CF.sub.3, C.sub.2F.sub.3,
n-C.sub.3F.sub.7, i-C.sub.3F.sub.7, C.sub.4F.sub.9,
CF.sub.3SO.sub.2, COOR.sup.4 and CN.
3. The device of claim 1 wherein m=3, y=0, and z=0.
4. The device of claim 1 wherein m=2, y=1, z=0, and L' is a
monoanionic bidentate ligand.
5. The device of claim 1 wherein m=1, y=1, and z=2.
6. The device of claim 5 wherein at least one L'' is a hydride.
7. The device of claim 4 wherein L' has a coordinating group
selected from amino, imino, amido, alkoxide, carboxylate,
phosphino, and thiolate.
8. The device of claim 4 wherein L' is selected from .beta.-enolate
ligands, N-analogs of .beta.-enolate ligands, S-analogs of
.beta.-enolate ligands, aminocarboxylate ligands, iminocarboxylate
ligands, salicylate ligands, hydroxyquinolinate ligands, S-analogs
of hydroxyquinolinate ligands, phosphinoalkoxide ligands, and a
ligand coordinated through a carbon atom that is part of an
aromatic group.
9. The device of claim 8 wherein L' is a .beta.-enolate having
Formula III: ##STR16## where R.sup.5 is the same or different at
each occurrence and is selected from hydrogen, halogen, substituted
or unsubstituted alkyl, aryl, alkylaryl and heterocyclic groups, or
adjacent R.sup.5 groups can be joined to form five- and
six-membered rings, which can be substituted, and R.sup.6 is
selected from alkyl, aryl, alkylaryl, heterocyclic groups, and
fluorine.
10. The device of claim 8 wherein L' is a phosphinoalkoxide having
Formula IV: ##STR17## where R.sup.7 can be the same or different at
each occurrence and is selected from H and C.sub.n(H+F).sub.2n+1,
R.sup.8 can be the same or different at each occurrence and is
selected from C.sub.n(H+F).sub.2n+1 and C.sub.6(H+F).sub.5, or
C.sub.6H.sub.5-n(R.sup.9).sub.n, R.sup.9=CF.sub.3, C.sub.2F.sub.5,
n-C.sub.3F.sub.7, i-C.sub.3F.sub.7, C.sub.4F.sub.9,
CF.sub.3SO.sub.2, and .phi. is 2 or 3.
11. The device of claim 8 wherein L' has Formula VII: ##STR18##
12. The device of claim 1 wherein the at least one layer is a
light-emitting layer.
13. The device of claim 12 wherein the light-emitting layer further
comprises a diluent.
14. The device of claim 13 wherein the diluent comprises a
polymeric or small molecule material, or a mixture thereof.
15. A compound having Formula I ##STR19## wherein: R.sup.1=H,
R.sup.4, OR.sup.4, N(R.sup.4).sub.2 R.sup.2=H, C.sub.nF.sub.2n+1,
C.sub.nF.sub.2n+1SO.sub.2, COOR.sup.4, CN R.sup.3=H,
C.sub.nF.sub.2n+1, C.sub.nF.sub.2n+1SO.sub.2, COOR.sup.4, CN
R.sup.4 is the same or different at each occurrence and is H,
alkyl, aryl, or adjacent R.sup.4 groups can join together to form a
5- or 6-membered ring, L'=a bidentate ligand and is not a
phenylpyridine, phenylpyrimidine, or phenylquinoline; L''=a
monodentate ligand, and is not a phenylpyridine, and
phenylpyrimidine, or phenylquinoline; m=1, 2 or 3, n is an integer
from 1 through 20, y=0, 1 or 2, and z=0 or an integer from 1
through 4, with the proviso that the compound is charge neutral and
the iridium is hexacoordinate.
16. A compound according to claim 15, wherein R.sup.2 and R.sup.3
in Formula I are independently selected from H, CF.sub.3,
C.sub.2F.sub.3, n-C.sub.3F.sub.7, i-C.sub.3F.sub.7, C.sub.4F.sub.9,
CF.sub.3SO.sub.2, COOR.sup.4 and CN.
17. A compound selected from Formula IX, Formula X, Formula XI, and
Formula XII: ##STR20##
18. A compound having a structure selected from Formula XIII,
Formula XIV, and Formula XV below: ##STR21##
19. A compound having Formula VIII: ##STR22##
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation-in-Part of U.S. Serial
No. ______(DuPont Docket No. UC0405 US NA), filed Jan. 30, 2004 and
a Continuation-In-Part of U.S. Ser. No. 10/366,295, filed Feb. 13,
2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to electroluminescent complexes of
iridium(III) with fluorinated phenylpyridines. It also relates to
electronic devices in which the active layer includes an
electroluminescent Ir(III) complex.
[0004] 2. Description of the Related Art
[0005] 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.
[0006] 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.
[0007] 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)pyridine-C'.sup.2,N]iridium(III).
(Polymer Preprints 2000, 41(1), 770.) Electroluminescent iridium
complexes having fluorinated phenylpyridine, phenylpyrimidine, or
phenylquinoline ligands have been disclosed in published
application WO 02/02714.
[0008] However, there is a continuing need for electroluminescent
compounds.
SUMMARY OF THE INVENTION
[0009] The present invention is directed to an iridium compound
(generally referred as "Ir(III) compounds") having Formula I:
##STR1## wherein: [0010] R.sup.1=H, R.sup.4, OR.sup.4,
N(R.sup.4).sub.2 [0011] R.sup.2=H, C.sub.nF.sub.2n+1,
C.sub.nF.sub.2n+1SO.sub.2, COOR.sup.4.sub.3 CN [0012] R.sup.3=H,
C.sub.nF.sub.2n+1, C.sub.nF.sub.2n+1SO.sub.2, COOR.sup.4, CN [0013]
R.sup.4 is the same or different at each occurrence and is H,
alkyl, aryl, or adjacent R.sup.4 groups can join together to form a
5- or 6-membered ring, [0014] L'=a bidentate ligand and is not a
phenylpyridine, phenylpyrimidine, or phenylquinoline; [0015] L''=a
monodentate ligand, and is not a phenylpyridine, and
phenylpyrimidine, or phenylquinoline; [0016] m=1, 2 or 3, [0017] n
is an integer from 1 through 20, [0018] y=0, 1 or 2, and [0019] z=0
or an integer from 1 through 4, [0020] with the proviso that the
compound is charge neutral and the iridium is hexacoordinate.
[0021] In another embodiment, the present invention is directed to
substituted 2-phenylpyridine precursor compounds from which the
above Ir(III) compounds are made. The precursor compounds have a
Formula II below: ##STR2## [0022] where R.sup.1, R.sup.2, and
R.sup.3 are as defined in Formula I above.
[0023] It is understood that there is free rotation about the
phenyl-pyridine bond. However, for the discussion herein, the
compounds will be described in terms of one orientation.
[0024] In another embodiment, the present invention is directed to
an organic electronic device having at least one layer comprising
the above Ir(III) compound, or combinations of the above Ir(III)
compounds.
DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a schematic diagram of one illustrative example of
a light-emitting device (LED).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The complexes of the invention have Formula I described
above.
[0027] In one embodiment of Formula I, R.sup.2 and R.sup.3 are
independently selected from H, CF.sub.3, C.sub.2F.sub.5,
n-C.sub.3F.sub.7, i- C.sub.3F.sub.7, C.sub.4F.sub.9,
CF.sub.3SO.sub.2, COOR' and CN.
[0028] In one embodiment of Formula I, L' ligand is a monoanionic
bidentate ligand. In general these ligands have N, O, P, or S as
coordinating atoms and form 5- or 6-membered rings when coordinated
to the iridium. Suitable coordinating groups include amino, imino,
amido, alkoxide, carboxylate, phosphino, thiolate, and the like.
Examples of suitable parent compounds for these ligands include
.beta.-dicarbonyls (.beta.-enolate ligands), and their N and S
analogs; amino carboxylic acids (aminocarboxylate ligands);
pyridine carboxylic acids (iminocarboxylate ligands); salicylic
acid derivatives (salicylate ligands); hydroxyquinolines
(hydroxyquinolinate ligands) and their S analogs; and
phosphinoalkanols (phosphinoalkoxide ligands).
[0029] The .beta.-enolate ligands generally have the Formula III
##STR3## where R.sup.5 is the same or different at each occurrence.
The R.sup.5 groups can be hydrogen, halogen, substituted or
unsubstituted alkyl, aryl, alkylaryl or heterocyclic groups.
Adjacent R.sup.5 and R.sup.6 groups can be joined to form five- and
six-membered rings, which can be substituted. In one embodiment,
R.sup.5 groups are selected from C.sub.n(H+F).sub.2n+1,
--C.sub.6H.sub.5, c-C.sub.4H.sub.3S, and c-C.sub.4H.sub.3O, where n
is an integer from 1 through 20. The R.sup.6 group can be H,
substituted or unsubstituted, alkyl, aryl, alkylaryl, heterocyclic
groups or fluorine.
[0030] Examples of suitable .beta.-enolate ligands include the
compounds listed below. The abbreviation for the .beta.-enolate
form is given below in brackets. [0031] 2,4-pentanedionate [acac]
[0032] 1,3-diphenyl-1,3-propanedionate [DI] [0033]
2,2,6,6-tetramethyl-3,5-heptanedionate [TMH] [0034]
4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate [TTFA] [0035]
7,7-dimethyl-1,1,1,2,2,3,3-heptafluoro-4,6-octanedionate [FOD]
[0036] 1,1,1,3,5,5,5-heptafluoro-2,4-pentanedionate [F7acac] [0037]
1,1,1,5,5,5-hexaflouro-2,4-pentanedionate [F6acac] [0038]
1-phenyl-3-methyl-4-1-butyryl-pyrazolinonate [FMBP]
[0039] The .beta.-dicarbonyl parent compounds, are generally
available commercially. The parent compound
1,1,1,3,5,5,5-heptafluoro-2,4-pentanedione,
CF.sub.3C(O)CFHC(O)CF.sub.3, can be prepared using a two-step
synthesis, based on the reaction of perfluoropentene-2 with
ammonia, followed by a hydrolysis step according to the procedure
published in Izv. AN USSR. Ser. Khim. 1980, 2827 This compound
should be stored and reacted under anhydrous conditions as it is
susceptible to hydrolysis.
[0040] The hydroxyquinolinate ligands can be substituted with
groups such as alkyl or alkoxy groups which may be partially or
fully fluorinated. Examples of suitable hydroxyquinolinate ligands
include (with abbreviation provided in brackets): [0041]
8-hydroxyquinolinate [8hq] [0042] 2-methyl-8-hydroxyquinolinate
[Me-8hq] [0043] 10-hydroxybenzoquinolinate [10-hbq] The parent
hydroxyquinoline compounds are generally available
commercially.
[0044] Phosphino alkoxide ligands generally have Formula IV:
##STR4## where [0045] R.sup.7 can be the same or different at each
occurrence and is selected from H and C.sub.n(H+F).sub.2n+1, [0046]
R.sup.8 can be the same or different at each occurrence and is
selected from C.sub.n(H+F).sub.2n+1 and C.sub.6(H+F).sub.5, or
C.sub.6H.sub.5-b(R.sup.9).sub.b, [0047] R.sup.9=CF.sub.3,
C.sub.2F.sub.5, n-C.sub.3F.sub.7, i-C.sub.3F.sub.7, C.sub.4F.sub.9,
CF.sub.3SO.sub.2, and [0048] .phi. is 2 or 3; [0049] b is 0-5; and
[0050] n is 1-20.
[0051] Examples of suitable phosphino alkoxide ligands include
(with abbreviation provided in brackets): [0052]
3-(diphenylphosphino)-1-oxypropane [dppO] [0053]
1,1-bis(trifluoromethyl)-2-(diphenylphosphino)-ethoxide [tfmdpeO]
Some of the parent phosphino alkanol compounds are available
commercially, or can be prepared using known procedures, such as,
for example, the procedure reported for tfmdpeO in Inorg. Chem.
1985, v.24, p.3680 or in J. Fluorine Chem. 2002, 117, 121
[0054] In one embodiment, L' is a ligand coordinated through a
carbon atom which is part of an aromatic group. The ligand can have
Formula V: Ar[--(CH.sub.2).sub.q--Y].sub.p (V) wherein Ar is an
aryl or heteroaryl group, Y is a group having a heteroatom capable
of coordinating to Ir, q is 0 or an integer from 1 through 20, p is
an integer from 1 through 5, and further wherein one or more of the
carbons in (CH.sub.2).sub.q can be replaced with a heteroatom and
one or more of the hydrogens in (CH.sub.2).sub.q can be replaced
with D or F.
[0055] In one embodiment, Y is selected from N(R.sup.10).sub.2,
OR.sup.10, SR.sup.10, and P(R.sup.11).sub.2, wherein R.sup.10 is
the same or different at each occurrence and is H,
C.sub.nH.sub.2n+1 or C.sub.n(H+F).sub.2n+1 and R.sup.11 is the same
or different at each occurrence and is selected from H, R.sup.10,
Ar and substituted Ar.
[0056] In one embodiment, Ar is phenyl, q is 1, Y is P(Ar).sub.2,
and p is 1 or 2.
[0057] Monodentate ligand L'' can be anionic or nonionic. Anionic
ligands include, but are not limited to, H-- ("hydride") and
ligands having C, O or S as coordinating atoms. Coordinating groups
include, but are not limited to alkoxide, carboxylate,
thiocarboxylate, dithiocarboxylate, sulfonate, thiolate, carbamate,
dithiocarbamate, thiocarbazone anions, sulfonamide anions, and the
like. In some cases, ligands listed above as L', such as
.beta.-enolates and phosphinoakoxides, can act as monodentate
ligands. The monodentate ligand can also be a coordinating anion
such as halide, nitrate, sulfate, hexahaloantimonate, and the like.
These ligands are generally available commercially.
[0058] The monodentate L'' ligand can be a non-ionic ligand, such
as CO or a monodentate phosphine ligand. The phosphine ligands can
have Formula VI PAr.sub.3 (VI) where Ar represents an aryl or
heteroaryl group. The Ar group can be unsubstituted or substituted
with alkyl, heteroalkyl, aryl, heteroaryl, halide, carboxyl,
sulfoxyl, or amino groups. The phosphine ligands are generally
available commercially.
[0059] In one embodiment of Formula I, the compound is
tris-cyclometallated, with m=3 and y=z=0. The compound can be
facial, meridional, or a combination of isomers.
[0060] In one embodiment of Formula I, m=2. In one embodiment, y=1
and z=0.
[0061] In one embodiment of Formula I, m=1. In one embodiment y=1
and z=2. In one embodiment at least one L'' ligand is a hydride. In
one embodiment L' is a ligand coordinated through a carbon atom
which is part of an aromatic group.
[0062] In one embodiment, the complexes having Formula I exhibit
blue luminescence. In one embodiment, the complexes have
photoluminescent and/or electroluminescent spectra which have a
maximum at 500 nm or Is less. In one embodiment, the maximum is
less than 480 nm.
[0063] Examples of iridium complexes having Formula I are given in
Table 1 below. TABLE-US-00001 TABLE 1 Complexes of Formula I where
z = 0 Complex R.sup.1 R.sup.2 R.sup.3 m L' y 1-a H H H 3 -- 0 1-b H
CF.sub.3 H 3 -- 0 1-c H COOMe H 3 -- 0 1-d H CN H 3 -- 0 1-e
CH.sub.3 H H 3 -- 0 1-f CH.sub.3 CF.sub.3 H 3 -- 0 1-g CH.sub.3
COOMe H 3 -- 0 1-h CH.sub.3 CN H 3 -- 0 1-i CH.sub.3 H H 2 PO 1 1-j
t-butyl H H 3 -- 0 1-k OMe CF.sub.3 H 3 -- 0 1-l OMe COOMe H 3 -- 0
1-m OMe CN H 3 -- 0 1-n OMe CF.sub.3 CF.sub.3 3 -- 0 1-o NMe.sub.2
H H 3 -- 0 1-p NMe.sub.2 CF.sub.3 H 3 -- 0 1-q NMe.sub.2 COOMe H 3
-- 0 1-r NMe.sub.2 CN H 3 -- 0 1-s NMe.sub.2 CF.sub.3SO.sub.2 H 3
-- 0 1-t NMe.sub.2 C.sub.2F.sub.5 H 3 -- 0 1-u NMe.sub.2
CF(CF.sub.3).sub.2 H 3 -- 0 1-v NMe.sub.2 H H 2 P0 1 1-w NPh.sub.2
CF.sub.3 H 3 -- 0 1-x NPh.sub.2 COOMe H 3 -- 0 1-y NPh.sub.2 CN H 3
-- 0
where "PO" represents the bidentate monoanionic ligand having
Formula VII: ##STR5##
[0064] In one embodiment of Formula I, the complex comprises a
ligand derived from ligand precursors having Formula VIII, Formula
IX, Formula X, Formula XI, and Formula XII below: ##STR6##
[0065] The Ir(III) compounds 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.
[0066] The iridium complexes of the invention are generally
prepared from the appropriate substituted 2-phenylpyridine
compound. The substituted 2-phenylpyridines, as shown in Formula II
above, are prepared, in good to excellent yield, using the Suzuki
coupling of the substituted 2-chloropyridine with arylboronic acid
as described in O. Lohse, P. Thevenin, E. Waldvogel Synlett, 1999,
45-48. This reaction is illustrated in Equation (1) below:
##STR7##
[0067] Examples of 2-phenylpyridine compounds are Formulae VIII
through XII, shown above.
[0068] The 2-phenylpyridines 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 in Equation (2) below: ##STR8## Tris-cyclometalated
iridium complexes having Formula I where m=3, can be isolated,
purified, and fully characterized by elemental analysis, .sup.1H
and .sup.19F NMR spectral data, and, for compounds, single crystal
X-ray diffraction. In some cases, mixtures of isomers are obtained.
Often the mixture can be used without isolating the individual
isomers.
[0069] Bis-cyclometalated iridium complexes having Formula I where
m=2, may, in some cases, be isolated from the reaction mixture
using the same synthetic procedures as preparing the
tris-cyclometalated complexes above. The complexes can also be
prepared by first preparing an intermediate iridium dimer ##STR9##
where L is the same or different and is a phenylpyridine ligand,
and Z is Cl or OR.sup.12, where R.sup.12 is H, CH.sub.3, or
C.sub.2H.sub.5. The iridium dimers can generally be prepared by
first reacting iridium trichloride hydrate with the
2-phenylpyridine and optionally adding NaOR.sup.12.
[0070] Mono-cyclometalated iridium complexes of the invention can,
in some cases, be isolated from reaction mixtures formed by the
above-described processes. Such mono-cyclometallated species can be
favored by use of phosphine containing ligands such as that shown
in formula VII and by using a stoichiometric excess of such ligands
(>2equivalents per Ir). These materials can be isolated from the
reaction mixture by standard techniques, such as chromatography on
silica with methylene chloride eluent.
Electronic Device
[0071] The present invention also relates to an electronic device
comprising at least one layer positioned between two electrical
contact layers, wherein the at least one layer of the device
includes the iridium complex of the invention. Devices frequently
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.
[0072] 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).
[0073] 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 and such diluent may be a charge
transport material or an inert matrix. A diluent may comprise
polymeric materials, small molecule or mixtures thereof. A diluent
may act as a processing aid, may improve the physical or electrical
properties of films containing the iridium compound, may decrease
self-quenching in the iridium compounds described herein, and/or
may decrease the aggregation of the iridium compounds described
herein. Non-limiting examples of suitable polymeric materials
include poly(N-vinyl carbazole), conjugated polymers, and
polysilane. Non-limiting examples of suitable small molecules
includes 4,4'-N,N'-dicarbazole biphenyl or tertiary aromatic
amines. Examples of suitable conjugated polymers include
polyarylenevinylenes, polyfluorenes, polyoxadiazoles, polyanilines,
polythiophenes, polyphenylenes, copolymers thereof and combinations
thereof. The conjugated polymer can be a copolymer having
non-conjugated portions, for example, acrylic, methacrylic, or
vinyl monomeric units. In one embodiment, the diluent comprises
homopolymers and copolmers of fluorine and substituted fluorenes.
When a diluent is used, the iridium compound is generally present
in a small amount. In one embodiment, the iridium compound is less
than 20% by weight, based on the total weight of the layer. In one
embodiment, the iridium compound is less than 10% by weight, based
on the total weight of the layer.
[0074] 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.
[0075] 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.
[0076] 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 477479 (11 Jun. 1992). At
least one of the anode and cathode should be at least partially
transparent to allow the generated light to be observed.
[0077] 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'-dimethyl)bip-
henyl]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]pyrazoline
(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), 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.
[0078] Examples of electron transport materials for layer 140
include metal chelated oxinoid compounds, such as
tris(8-hydroxyquinolato)aluminum (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)-1,3,4-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.
[0079] 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 lanthamides, 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.
[0080] 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.
[0081] It is understood that each functional layer may be made up
of more than one layer.
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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, where "a" and "b" represent different coordinating
atoms, having octahedral geometry, in which the three "a" atoms 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"
atoms occupy three positions such that two are trans to each other.
The term "hexacoordinate" is intended to mean that six groups or
points of attachment are coordinated to a central metal. 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. In the Formulae and
Equations, the letters L, R, Y, and Z are used to designate atoms
or groups which are defined within. All other letters are used to
designate conventional atomic symbols. The term "(H+F)" is intended
to mean all combinations of hydrogen and fluorine, including
completely hydrogenated, partially fluorinated or perfluorinated
substituents.
[0086] As used herein, the terms "comprises," "comprising,"
"includes," "including," "has," "having" or any other variation
thereof, are intended to cover a non-exclusive inclusion. For
example, a process, method, article, or apparatus that comprises a
list of elements is not necessarily limited to only those elements
but may include other elements not expressly listed or inherent to
such process, method, article, or apparatus. Further, unless
expressly stated to the contrary, "or" refers to an inclusive or
and not to an exclusive or. For example, a condition A or B is
satisfied by any one of the following: A is true (or present) and B
is false (or not present), A is false (or not present) and B is
true (or present), and both A and B are true (or present).
[0087] Also, use of the "a" or "an" are employed to describe
elements and components of the invention. This is done merely for
convenience and to give a general sense of the invention. This
description should be read to include one or at least one and the
singular also includes the plural unless it is obvious that it is
meant otherwise.
[0088] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. All
publications, patent applications, patents, and other references
mentioned herein are incorporated by reference in their entirety.
In case of conflict, the present specification, including
definitions, will control. In addition, the materials, methods, and
examples are illustrative only and not intended to be limiting.
EXAMPLES
[0089] 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
[0090] This example illustrates the preparation of a ligand
precursor compound having Formula II, where R.sup.2=CF.sub.3, and
R.sup.1=R.sup.3=H. Preparation of
2,4-difluoro-3-trifluoromethylbenzeneboronic acid ##STR10##
[0091] To a solution of 2.4 g of
2,6-difluoro-trifluoromethylbenzene in the mixture of 25 ml of dry
ether and 25 ml of dry THF 7 ml of solution 2M butyl lithium in
pentane was added dropwise at -70.degree. C. The reaction mixture
was stirred 15 min at -70.degree. C. and 2 g of trimethylborate was
added. The reaction was allowed to warm up to 25.degree. C. and was
diluted with 200 ml of 10% hydrochloric acid and extracted with
ether (2.times.50 ml). The combined organic layers were washed with
water (2.times.100 ml), dried over MgSO.sub.4 and solvent was
remover under vacuum at 50.degree. C. to leave 3.4 g of crude
boronic acid (containing .about.50% of THF), which was used for the
next reaction without further purification. .sup.1H NMR
(CDCl.sub.3): 6.9 (2H, t), 7.9 (1H, q), 5.3 (2H, br s); .sup.19F
NMR: -56.68(3F, t), -106.0 (1F, m), -108.0(1F, m). Preparation of
2-(2,4-difluoro-3-trifluoromethylphenyl)-pyridine Formula VIII
##STR11##
[0092] To a solution of 10 g potassium carbonate in 100 ml of
degassed water, the solution of 3.4 g
2,4-difluoro-3-trifluoromethylbenzeneboronic acid (50% purity, the
rest THF) in 50 ml of monoglyme was added, followed by the addition
of 3.5 g of 2-bromopyridine, 0.1 g of
dicyclohexyl(biphenyl)phosphine, 0.05 g of palladium acetate. The
reaction mixture was refluxed (90-95.degree. C.) for 16 h. The
reaction mixture was diluted with 500 ml of water, extracted with
dichloromethane (3.times.50 ml), the organic layer was washed with
water (1.times.300 ml), dried over MgSO.sub.4 and solvent was
removed under vacuum. Crude product (3.2 g) was dissolved in 50 ml
of hexane and the solution was passed through a short plug of
silicagel (Silicagel 60, EM Science). The column was washed with
another 30 ml of hexane. From final solution hexane was removed
under vacuum to leave 1.6 g of slightly yellow liquid, which based
on NMR analysis was
2-(2,4-difluoro-3-trifluoromethylphenyl)-pyridine, containing 27%
of 2-bromopyridine. The crude material was used for the next
reaction without further purification.
Example 2
[0093] This example illustrates the preparation of a complex of the
invention having Formula XIII: ##STR12##
[0094] 0.52 g of the ligand precursor from Example 1 was mixed with
0.38 g iridium chloride in 10 mL 2-ethoxyethanol and 1 mL water.
This mixture was refluxed under nitrogen for 30 mins. The mixture
was cooled, and to the cooled mixture was added 0.2 g
di-t-butylacetylacetone (tetramethylheptanedione) and 300 mg sodium
carbonate. Refluxing was continued for at least 30 mins. This was
then cooled, evaporated to dryness in a nitrogen stream, extracted
into methylene chloride, and filtered. The methylene chloride
extract was dark orange in color and blue-green luminescent. The
methylene chloride solution was then evaporated to dryness and
chromatographed on silica to isolate the blue luminescent fraction.
This fraction was then recrystallized from methylene
chloride/methanol.
[0095] Analysis by nmr indicated the material to be the complex
having Formula XIII.
Example 3
[0096] This example illustrates the preparation of the precursor
phosphino-alcohol compound
1,1-bis(trifluoromethyl)-2-bis(triphenylphosphino)-ethanol
("PO-1H") for the ligand having Formula VII. The compound was made
by two different methods.
Method a:
[0097] The phosphino alkanol was made according to the procedure in
Inorg. Chem. (1985), 24 (22), pp. 3680-7. Under nitrogen,
1,1-bis(trifluoromethyl)ethylene oxide (12 g, 0.066 mol) was added
dropwise to a pre-cooled (10-15.degree. C.) solution of
diphenylphosphine (10 g, 0.053 mol) in dry THF (50 mL). The
reaction mixture was stirred at 25.degree. C. for 2 days, after
which NMR analysis indicated >90% conversion. The solvent was
removed under vacuum and the residual viscous oil was distilled
under vacuum to give 8 g of the fraction (b.p. 110-114.degree. C.
at 0.05 mm Hg) which crystallized on standing. Both the NMR data
and m.p. (59-62.degree. C.) of this material (>95% purity) were
consistent with those reported in: Boere, R. T. et al., Inorg.
Chem. (1985), 24, 3680. .sup.1H NMR (CDCl.sub.3, 20.degree. C.),
.delta.: 7.3-7.8 (m, 10H, arom. H); 2.8 (br. s.; 1H, OH); 2.2 (s,
2H, CH.sub.2). .sup.19F NMR (CDCl.sub.3, 20.degree. C.), .delta.:
-77.3 (d, J.sub.F-P=15.5 Hz). .sup.31P NMR (CDCl.sub.3, 20.degree.
C.), .delta.: -24.4 (septet, J.sub.P-F=15.5 Hz).
Method b:
[0098] (i) Preparation of 1,1-bis(trifluoromethyl)-2-bromoethanol,
BrCH.sub.2C(CF.sub.3).sub.2OH. 1,1-bis(trifluoromethyl)oxirane (100
g; 0.55 mol; prepared as described in WO 00/66575, 2000, to
DuPont). was added slowly to 100 ml of 47% aqueous HBr placed in a
round bottom glass flask equipped with a dry-ice condenser,
thermometer, and magnetic stir bar at 30-40.degree. C. The reaction
mixture was stirred under reflux for 3 h. At that point the
temperature raised to 90.degree. C. After cooling to room
temperature, the bottom layer was separated, dried over MgSO.sub.4,
and distilled to give 104 g (72%) of BrCH.sub.2C(CF.sub.3).sub.2OH,
b.p. 101-103.degree. C. .sup.1H NMR (CDCl.sub.3): 3.50 (br s, 1H,
--OH), 3.70(s, 2H, CH.sub.2). .sup.19F NMR (CDCl.sub.3): -75.9 (s).
This material was dried over freshly calcined molecular sieves (4
A) prior to the next step.
[0099] (ii) Under nitrogen, to a stirring solution of
1,1-bis(trifluoromethyl)-2-bromoethanol (5.64 g; prepared as
described above) in dry ether (110 mL) cooled to -78.degree. C.,
was added drop-wise 1.6 M n-BuLi in hexanes (Aldrich; 27 mL). After
1 h at -78.degree. C., chlorodiphenylphosphine (Strem; 4.53 g) was
added drop-wise, at vigorous stirring, to the resulting solution of
the dilithiated derivative. After stirring the mixture for 3 h 20
min at -78.degree. C., it was allowed to warm slowly to room
temperature and then stirred at room temperature overnight. The
solvents were removed under vacuum. Dichloromethane (10 mL) and
trifluoroacetic acid (1.66 mL) were added to the residue, and the
mixture was chromatographed on a silica gel column (5.times.25 cm)
with dichloromethane. The product was isolated as an oil which
crystallized upon drying under vacuum. The yield of the product as
white crystalline solid was 5.3 g (71%). The compound was found
identical with the material synthesized according to method a.
Example 4
[0100] This example illustrates the preparation of a complex of the
invention having Formula XIV: ##STR13##
[0101] 0.26 g of the ligand precursor from Example 1 was mixed with
0.19 g iridium chloride in 10 mL 2-ethoxyethanol and 1 mL water.
This mixture was refluxed under nitrogen for 30 mins. The mixture
was cooled, and to the cooled mixture was added 0.37 g
phosphinoalcohol (2eq) from Example 3 and 300 mg sodium carbonate.
Refluxing was continued for at least 30 mins. This was then cooled,
evaporated to dryness in a nitrogen stream, extracted into
methylene chloride, and filtered. The methylene chloride extract
was light yellow in color and blue green luminescent. This solution
was evaporated to dryness and chromatographed to isolate the blue
luminescent fraction.
[0102] Analysis by TLC showed a very deep blue phosphorescent spot
running at the solvent front and a turquoise phosphorescent spot
running behind as the major fraction. A silica column with
methylene chloride eluent was used to separate the two materials.
Two fractions were collected: (i) a small amount of the fast
running bluer material and (ii) a larger amount of pale yellow
glassy material which was turquoise luminescent. Both of these
materials were recrystallized from ethylacetate/hexanes to give
pale crystals--blocks for the first material (i), and needles for
the second material (ii). The major material was approximately 250
mg of fluffy pale yellow needles. Solutions of this material were
sky blue photoluminescent. The solid was turquoise
photoluminescent. Analysis by nmr indicated that this material had
Formula XIV.
[0103] The second material was purified by additional
chromatography using 50:50 hexanes:methylene chloride. A
non-luminescent yellow band washed out ahead of the bright blue
photoluminescent band. The blue photoluminescent band material was
collected as a white solid (-25 mg). Analysis by nmr indicated that
this material was a monocyclometallated hydrido material having
Formula XV: ##STR14##
[0104] In this complex there are two phosphino alcohol ligands, one
which is bidentate and one which is monodentate.
* * * * *