U.S. patent application number 10/835481 was filed with the patent office on 2005-11-03 for organic light-emitting devices.
Invention is credited to Chan, Siu-Chung, Che, Chi-Ming.
Application Number | 20050244672 10/835481 |
Document ID | / |
Family ID | 35187456 |
Filed Date | 2005-11-03 |
United States Patent
Application |
20050244672 |
Kind Code |
A1 |
Che, Chi-Ming ; et
al. |
November 3, 2005 |
Organic light-emitting devices
Abstract
Disclosed are electrophosphorescent organic metal complexes with
formula (I), (H), (III) or (IV), of either geometrical isomers,
comprising two bidentate NN-type ligands, or two NO-type ligands,
or a tetradentate NNNN-type ligand or a tetradentate NOON-type
ligand, and a transition metal. These electrophosphorescent
materials are valuable to the application in organic light-emitting
devices (OLEDs), including red-, orange-, or yellow-light
OLEDs.
Inventors: |
Che, Chi-Ming; (Hong Kong,
CN) ; Chan, Siu-Chung; (Hong Kong, CN) |
Correspondence
Address: |
DICKSTEIN SHAPIRO MORIN & OSHINSKY LLP
1177 AVENUE OF THE AMERICAS (6TH AVENUE)
41 ST FL.
NEW YORK
NY
10036-2714
US
|
Family ID: |
35187456 |
Appl. No.: |
10/835481 |
Filed: |
April 30, 2004 |
Current U.S.
Class: |
428/690 ;
257/102; 313/504; 313/506; 427/66; 428/917 |
Current CPC
Class: |
C09K 11/06 20130101;
C09K 2211/185 20130101; H01L 51/0087 20130101; H05B 33/14 20130101;
C09K 2211/1044 20130101; H01L 51/5016 20130101; C09K 2211/1007
20130101; C09K 2211/1011 20130101; H01L 51/002 20130101; Y10S
428/917 20130101; C09K 2211/1059 20130101 |
Class at
Publication: |
428/690 ;
428/917; 313/504; 313/506; 257/102; 427/066 |
International
Class: |
H05B 033/14 |
Claims
What is claimed is:
1. A heterostructured organic light-emitting device comprising at
least one emissive layer comprising at least one host material and
at least one dopant complex, wherein the dopant complex comprises a
transition metal atom coordinated to two bidentate NN ligands, or
two bidentate NO ligands, or a tetradentate NNNN ligand, or a
tetradentate NOON ligand.
2. The heterostructured organic light-emitting device of claim 1,
wherein the emissive layer comprises one dopant complex, which
dopant complex dopes the host material.
3. The heterostructured organic light-emitting device of claim 2,
wherein the dopant complex is geometrically in the
cis-configuration.
4. The heterostructured organic light-emitting device of claim 2,
wherein the dopant complex is geometrically in the
trans-configuration.
5. The heterostructured organic light-emitting device of claim 1,
wherein the emissive layer is a sublimation, vacuum deposition,
vapor deposition or spin-coating layer.
6. The heterostructured organic light-emitting device of claim 1,
wherein the dopant complex is: 3132or a mixture thereof, wherein M
is a transition metal selected from the group consisting of Ni, Pd
and Pt; each R.sup.1-R.sup.10 is independently --H, --OH,
--NH.sub.2, -halogen, --CN, --NO.sub.2, --R.sup.13, --OR.sup.14
--NHR.sub.4, or --N(R.sup.14).sub.2; R.sub.11 is
--(C(R.sup.15).sub.2).sub.n-, 33each R.sup.12 is independently --H,
--(C.sub.1-C.sub.6)alkyl, -phenyl, -naphthyl; -halogen, or --CN;
R.sup.13 is --(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl, each
of which is unsubstituted or substituted with one or more
--(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl; R.sup.14 is as
defined above for R.sup.13; R.sup.15 is as defined above for
R.sup.1; each x is independently a carbon or nitrogen atom; and n
is an integer from 1 to 6.
7. The heterostructured organic light-emitting device of claim 6,
wherein M is Pt.
8. The heterostructured organic light-emitting device of claim 7,
having structure I or II.
9. The heterostructured organic light-emitting device of claim 7,
having structure III or IV.
10. The heterostructured organic light-emitting device of claim 7,
wherein the dopant complex is selected from the group consisting
of: 34or a mixture thereof.
11. The heterostructured organic light-emitting device of claim 1,
wherein the emissive layer comprises 0.5 to 8.0 weight % dopant
complex based on the weight of host material.
12. The heterostructured organic light-emitting device of claim 1,
wherein the emissive layer comprises a dopant complex exhibits an
electroluminescence of visible color.
13. The heterostructured organic light-emitting device of claim 1,
wherein the emissive layer comprises a dopant complex which
exhibits red, orange or yellow electroluminescence.
14. The heterostructured organic light-emitting device of claim 1,
wherein the host material is selected from the group consisting of
beryllium bis(2-(2'-hydroxyphenyl)pyridine,
4,4'-bis(carbazol-9-yl)biphenyl (CBP),
N,N'-diphenyl-N,N'-bis(1-naphthalene)benzidine (.alpha.-NPB),
N,N'-diphenyl-N,N'-bis(2-naphthalene)benzidine (.beta.-NPB),
N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD),
4,4',4"-tris(N-3-methylphenyl-N-phenylamino)triphenylamine
(m-TDATA) or tetrakis(diarylamino)-9,9'-spirobifluorene.
15. A method for preparing a heterostructured organic light
emitting devices which comprises providing an emissive layer,
wherein the emissive layer comprising at least one host material
and at least one dopant complex, the dopant complex comprising a
transition metal coordinated to two bidentate NN ligands, or two
bidentate NO ligands, or a tetradentate NNNN ligand, or a
tetradentate NOON ligand.
16. The method of claim 15, wherein the dopant complex in emissive
layer is: 3536or a mixture thereof, wherein M is a transition metal
selected from the group consisting of Ni, Pd and Pt; each
R.sup.1-R.sup.10 is independently --H, --OH, --NH.sub.2, -halogen,
--CN, --NO.sub.2, --R.sup.13, --OR.sup.4, --NHR.sup.14, or
--N(R.sup.4).sub.2; R.sub.11 is 13 (C(R.sup.15).sub.2).sub.n-,
37each R.sup.12 is independently --H, --(C.sub.1-C.sub.6)alkyl,
-phenyl, -naphthyl; -halogen, or --CN; R.sup.13 is
--(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl, each of which is
unsubstituted or substituted with one or more
--(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl; R.sup.14 is as
defined above for R.sup.13; and R.sup.15 is as defined above for
R.sup.1; each x is independently a carbon or nitrogen atom; and n
is an integer number from 1 to 6.
17. The method of claim 15, wherein M is Pt.
18. The method of claim 17, wherein the dopant complex in emissive
layer is selected from the group consisting of: 38or a mixture
thereof
19. The method of claim 15, wherein the emissive layer comprises
0.5 to 8.0 weight % dopant complex based on weight of host
material.
20. The method of claim 15, wherein the emissive layer comprises a
dopant complex exhibits an electroluminescence of visible
color.
21. The method of claim 20, wherein the emissive layer comprises a
dopant complex which exhibits red, orange or yellow
electroluminescence.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to efficient organic
light-emitting devices (OLEDs) which comprise a transition metal
complex, wherein the transition metal complex, of either
geometrical isomers, comprises two bidentate NN-type ligands, or
two bidentate NO-type ligands, or a tetradentate NNNN-type ligand,
or a tetradentate NOON-type ligand, and a transition metal atom as
the electrophosphorescent emitter. The invention also relates to
methods for preparing thin film OLEDs and their applications such
as in liquid crystal displays, plasma panel displays and
light-emitting diodes.
BACKGROUND OF THE INVENTION
[0002] Organic light-emitting devices (OLEDs) are finding
applications as next-generation flat-panel displays (FPDs), liquid
crystal displays (LCDs), and plasma display panels (PDPs). This has
been driven by their favorable properties including lightweight,
fast video response and low power consumption. To this end,
organometallic compounds exhibiting electroluminescence are
particularly attractive for electrophosphorescent applications,
since both the ligand structure and the central metal atom can be
varied to modify the properties of the device using these
compounds.
[0003] An organic light-emitting device (OLED) is an energy
conversion device which emits light when current is applied. A
multilayer OLED is generally comprised of hole and electron
injection layers, hole- and electron-transporting layers, an
emissive layer, metal oxide layer and metal electrodes. The use of
organic small molecules and polymers in the emissive layer has
attracted much attention due to their potential applications in
full-color large-area flat-panel displays. Tang and VanSlyke first
disclosed that organic small molecules can be prepared as
thin-films by vacuum deposition to form multilayer organic
light-emitting devices (OLEDs) (see Tang et al., Appl. Phys. Lett.
51:913, (1987)).
[0004] Investigations on organic small molecules have been made in
order to improve the performance of OLEDs. In general, fluorescent
and phosphorescent materials are employed as light emitters in the
emissive layer of OLEDs. Light emission from a fluorescent compound
occurs as a result of formation of singlet excitons in the emissive
layer of the electroluminescent device. U.S. Pat. No. 6,310,360
disclosed that theoretically 25% singlet excitons and 75% triplet
excitons are produced after recombination of holes and electrons in
the emissive layer of an electroluminescent device. The singlet
excitons transfer their energy to the singlet excited state while
the triplet excitons transfer their energy to triplet excited
state. Most of the organic small molecules exhibit fluorescence;
hence, only 25% of the generated excitons are utilized resulting in
the device with low external efficiency.
[0005] In contrast to fluorescent compounds, a series of effective
phosphorescent iridium complexes with different color emissions has
been reported jointly by Thompson et al. at the University of
Southern California and Forrest et al. at Princeton University (see
U.S. Pat. No. 6,515,298 B2; U.S. patent application Publication
No.20020182441 A1; Lamansky et al., J. Am. Chem. Soc., 123:4304
(2001); and Xie et al., Adv. Mat., 13:1245 (2001)). Che et al. also
demonstrated the use of organic metal complexes employing various
metal centres such as platinum(II), copper(I), gold(I), and
zinc(II) as OLED emitters (see U.S. patent application Publication
No. 23205707 A1; U.S. patent application Publication No. 22179885
A1; Y.-Y. Lin et al., Chem. Eur. J., 29:1263 (2003); Lu et al.,
Chem. Commun., 206 (2002); Ma et al., New J. Chem., 263 (1999); Ma
et al., Appl. Phys. Lett., 74:1361 (1999); Ho et al., Chem.
Commun., 2101 (1998); and Ma et al., Chem. Commun., 2491
(1998)).
[0006] A variety of light-emitting compounds, especially red
emitters, have been investigated as active emitters in a number of
device structures. U.S. Pat. No. 6,048,630 disclosed OLEDs based on
phosphorescent Pt(OEP) complex (H2OEP=octylethylporphyrin) which
emits saturated red electroluminescence. Thompson and Forrest et
al. reported a red phosphorescent material
(bis(2-(2'-benzo[4,5-a]thienyl)pyridinato-N, C.sup.3) iridium
(acetylacetonate) [Btp2Ir(acac)]) with high-efficiency
(.eta..sub.ext=7.0.+-.0.5%) (see Adachi et al., Appl. Phys. Lett.,
78:1622 (2001)). In addition, europium complex employed as red
emissive dopant in OLED (Eu(TTA).sub.3phen,
TTA=thenoyltrifluoroacetone; phen=1,10-phenanthroline) was also
reported to show sharp red electroluminescence (see Adachi et al.,
J. Appl. Phys., 87:8049, (2000)).
[0007] Efforts in the development of red phosphorescent emitters
with high efficiency for OLEDs are geared towards the full-color
flat panel display application. Even though remarkable progress has
been made, challenges such as optimization of stability and
efficiency of OLEDs need to be met before commercialization. It is,
therefore, particularly contemplated to develop phosphorescent
materials, which exhibit electroluminescent (EL) emissions in
visible light region, with high efficiencies and good
stabilities.
SUMMARY OF THE INVENTION
[0008] The main objective of this invention is to provide organic
light-emitting devices (OLEDs) comprising an emissive layer, which
employs at least one dopant complex as an electrophosphorescent
emitter. The devices should exhibit low turn-on voltages, high
luminance, high efficiencies, and desirable colors.
[0009] Another objective of the present invention is to provide an
OLED structure, which employs an emissive layer comprising at least
one electrophosphorescent dopant complex and at least one host
material.
[0010] Yet another objective is to provide OLEDs that emit
desirable colors by varying concentration of the dopant complex in
the emissive layer under different applied voltages. It is
concerned with the efficiencies of the selected dopant complexes,
which can be used at low concentration levels in OLEDs.
[0011] In one embodiment, the invention relates to a
heterostructured organic light-emitting device comprising:
[0012] a substrate upon which a first electrode is placed;
[0013] a hole-transporting layer;
[0014] at least one emissive layer comprising at least one host
material and at least one dopant complex; the dopant complex, of
either geometrical isomers, comprising at least one transition
metal coordinated to two bidentate NN-type ligands, or two
bidentate NO-type ligands, or a tetradentate NNNN-type ligand, or a
tetradentate NOON-type ligand;
[0015] a hole-blocking layer;
[0016] an electron-transporting layer;
[0017] a charge injection layer; and
[0018] a second electrode sandwiching the hole-transporting layer,
emissive layer, hole-blocking layer, electron-transporting layer
and charge injection layer between the first and the second
electrode.
[0019] In preferred embodiments, the invention relates to OLED
comprising an emissive layer which contains at least one transition
metal complex. The transition metal complexes, of either
geometrical isomers, contain two bidentate NN-type ligand, or two
bidentate NO-type ligands, or a tetradentate NNNN-type ligand, or a
tetradentate NOON-type ligand, and a transition metal as the
electrophosphorescent dopant complexes.
[0020] In a preferred embodiment, the invention relates to a
heterostructured OLED comprising one or more dopant complexes of
following formulae: 12
[0021] or mixtures thereof, wherein
[0022] M is a transition metal selected from the group consisting
of Ni, Pd and Pt;
[0023] each R.sup.1-R.sup.10 is independently --H, --OH,
--NH.sub.2, -halogen, --CN, --NO.sub.2, --R.sup.13,
--OR.sup.14,
[0024] --NHR.sup.14, or --N(R.sup.14).sub.2;
[0025] R.sup.11 is --(C(R.sup.15)2)n, 3
[0026] each R.sup.12 is independently --H,
--(C.sub.1-C.sub.6)alkyl, -phenyl, -naphthyl; -halogen, or
--CN;
[0027] R.sup.13 is --(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl,
each of which is unsubstituted or substituted with one or more
--(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl;
[0028] R.sup.14 is defined as above for R.sup.13;
[0029] R.sup.15 is defined as above for R.sup.1;
[0030] x is independently a carbon or nitrogen atom; and
[0031] n is an integer number from 1 to 6.
[0032] Another embodiment, the present invention relates to a
method of preparing heterostructured organic light emitting devices
with yellow, orange or red color emissions. The method includes the
steps of
[0033] providing a substrate upon which a first electrode is
placed;
[0034] providing a hole-transporting layer on top of the first
electrode;
[0035] forming an emissive layer on top of the hole-transporting
layer, the emissive layer comprising at least one host material and
at least one dopant complex, the dopant complex, of either
geometrical isomers, comprising a transition metal coordinated to
two bidentate NN-type ligands, or two bidentate NO-type ligands, or
a tetradentate NNNN-type ligand, or a tetradentate NOON-type
ligand.
[0036] providing a hole-blocking layer on top of the emissive
layer;
[0037] providing an electron-transporting layer on top of the
hole-blocking layer;
[0038] providing a charge injection layer on top of the
electron-transporting layer; and
[0039] providing a second electrode on top of the charge injection
layer.
[0040] In a preferred embodiments of the present invention
includes, but is not limited to, OLEDs comprising heterostructures
for producing red, orange or yellow electroluminescence; the
devices contain an anode (ITO glass substance), a hole-transporting
layer (N,N'-diphenyl-N,N'-bis(2-nap- hthalene)benzidine
(.beta.-NPB)), an emissive layer comprising a host material
(4,4'-bis(carbazol-9-yl)biphenyl (CBP)) and an
electrophosphorescent dopant complex as illustrated in Formulae I,
II, III or IV herein), a hole-blocking layer
(2,9-dimethyl-4,7-diphenyl-1,10-- phenanthroline (BCP)), an
electron-transporting layer (tris(8-hydroxyquinolato) aluminum
(Alq.sub.3)), a charge injection layer (lithium fluoride) and a
cathode (aluminum metal).
[0041] More preferably, the OLEDs employing electrophosphorescent
dopant complexes as illustrated in Formulae I, II, III or IV herein
demonstrate red, orange or yellow emission while a current is
applied.
[0042] In according with the present invention, the high efficiency
OLEDs can be applied to the field of electronic flat panel display,
display board for sign lamp or light source.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1. Absorption, excitation and emission spectra of
dopant complex 1 in CH.sub.3CN
[0044] FIG. 2. Absorption, excitation and emission spectra of
dopant complex 2 in CH.sub.3CN
[0045] FIG. 3. Absorption, excitation and emission spectra of
dopant complex 4 in CH.sub.3CN
[0046] FIG. 4. Schematic diagram of OLED in present invention
[0047] FIG. 5. EL spectra of OLED A with 4.0 wt. % dopant 1 at
different dopant concentrations under 8 V
[0048] FIG. 6. EL spectra of OLED A with 4.0 wt. % dopant 1 at
different applied voltages
[0049] FIG. 7. V-I-B curve of OLED A with 4.0 wt. % dopant 1
[0050] FIG. 8. External quantum efficiency and luminous efficiency
of OLED A with 4.0 wt % dopant 1
[0051] FIG. 9. EL spectra of OLED B with 5 wt. % dopant 2 at
different dopant concentrations at 8 V
[0052] FIG. 10. EL spectra of OLED B with 5 wt. % dopant 2 at
different applied voltages
[0053] FIG. 11. V-I-B curve of OLED B with 5 wt. % dopant 2
[0054] FIG. 12. The external quantum efficiency and luminous
efficiency of OLED B with 5.0 wt. % dopant 2
[0055] FIG. 13. EL spectra of OLED C with 3 wt. % dopant 19 at
different dopant concentrations at 8 V
[0056] FIG. 14. EL spectra of OLED C with 3 wt. % dopant 19 at
different applied voltages
[0057] FIG. 15. V-I-B curve of OLED C with 3 wt. % dopant 19
[0058] FIG. 16. The external quantum efficiency and luminous
efficiency of OLED C with 3.0 wt. % dopant 19
[0059] FIG. 17. EL spectra of OLED D with 4 wt. % dopant 51 at
different dopant concentrations at 8 V
[0060] FIG. 18. EL spectra of OLED D with 4 wt. % dopant 51 at
different applied voltages
[0061] FIG. 19. V-I-B curve of OLED D with 4 wt. % dopant 51
[0062] FIG. 20. The external quantum efficiency and luminous
efficiency of OLED D with 4.0 wt. % dopant 51
[0063] FIG. 21 EL spectra of OLED E with 1.5 wt. % dopant 99 at
different dopant concentrations at 8 V
[0064] FIG. 22 EL spectra of OLED E with 1.5 wt. % dopant 99 at
different applied voltages
[0065] FIG. 23 V-I-B curve of OLED E with 1.5 wt. % dopant 99
[0066] FIG. 24 External quantum efficiency and luminous efficiency
of OLED E with 1.5 wt. % dopant 99
[0067] FIG. 25 EL spectra of OLED F with 1.6 wt. % dopant 104 at
different dopant concentrations at 8 V
[0068] FIG. 26 EL spectra of OLED F with 1.6 wt. % dopant 104 at
different applied voltages
[0069] FIG. 27 V-I-B curve of OLED F with 1.6 wt. % dopant 104
[0070] FIG. 28 External quantum efficiency and luminous efficiency
of OLED F with 1.6 wt. % dopant 104
DETAILED DESCRIPTION OF THE INVENTION
[0071] Some definitions useful for describing the present invention
are provided below:
[0072] As used herein, the phrase "bidentate NN-type ligands"
refers to a molecule containing an imine group and either a pyrrol
group, a pyrazol group, an imidazol group, or a triazol group,
which ligand is coordinated to a metal through the nitrogen atoms
of these groups.
[0073] As used herein, the phrase "bidentate NO-type ligands"
refers to a molecule containing an imine group and a phenoxide
group, which ligand is coordinated to a metal through the nitrogen
and oxygen atoms of these groups.
[0074] As used herein, the phrase "tetradentate NNNN-type ligand"
refers to a molecule containing a two imine groups and either two
pyrrol groups, two pyrazol groups, two imidazol groups, or two
triazol groups, which ligand is coordinated to a metal through the
nitrogen atoms of these groups.
[0075] As used herein, the phrase "tetradentate NOON-type ligand"
refers to a molecule containing two imine groups and two phenoxide
groups, which ligand is coordinated to a metal through the nitrogen
and oxygen atoms of these groups.
[0076] As used herein, the phrase "light-emitting device" refers to
structures presenting an assymetric impedance to current.
Typically, such a device allows current to flow more easily in one
direction when it is said to be forward biased. However, in some
devices of the present invention, significant current may flow in
the reverse biased state as well with generation of light.
[0077] The present invention is related to a heterostructured OLED
comprising an emissive layer, wherein the emissive layer comprises
at least one host material and at least one emissive material.
Preferably, the emissive material is a dopant complex, of either
geometrical isomers, comprising a transition metal coordinated to
two bidentate NN-type ligands, or two bidentate NO-type ligands, or
a tetradentate NNNN-type ligand, or a tetradentate NOON-type
ligand. The dopant complex can be present as a monomer, a dimer, an
oligomer, or mixtures thereof.
[0078] In one embodiment, the invention relates to a
heterostructured organic light-emitting device comprising:
[0079] a substrate upon which a first electrode is placed;
[0080] a hole-transporting layer;
[0081] at least one an emissive layer comprising at least one host
material and at least one dopant complex; the dopant complex, of
either geometrical isomers, comprising at least one transition
metal coordinated to two bidentate NN-type ligands or two bidentate
NO-type ligands or a tetradentate NNNN-type ligand or a
tetradentate NOON-type ligand;
[0082] a hole-blocking layer;
[0083] an electron-transporting layer;
[0084] a charge injection layer; and
[0085] a second electrode sandwiching the hole-transporting layer,
emissive layer, hole-blocking layer, electron-transporting layer
and charge injection layer between the first and the second
electrode.
[0086] Preferably, the emissive materials are dopant complexes, of
either geometrical isomers, comprising two bidentate NN-type
ligands or two bidentate NO-type ligands or a tetradentate
NNNN-type ligand or a tetradentate NOON-type ligand and a
transition metal atom. More preferably, the emissive materials
include dopant complexes of the following formulae: 45
[0087] or mixtures thereof, wherein
[0088] M is a transition metal selected from the group consisting
of Ni, Pd and Pt;
[0089] each R.sup.1-R.sup.10 is independently --H, --OH,
--NH.sub.2, -halogen, --CN, --NO.sub.2, --R.sup.13,
--OR.sup.14,
[0090] NHR.sup.14, or --N(R.sup.14).sub.2;
[0091] R.sup.11 is --(C(R.sup.15).sub.2).sub.n-, 6
[0092] each R.sup.12 is independently --H,
--(C.sub.1-C.sub.6)alkyl, -phenyl, -naphthyl; -halogen, or
--CN;
[0093] R.sup.13 is --(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl,
each of which is unsubstituted or substituted with one or more
--(C.sub.1-C.sub.6)alkyl, -phenyl, or -naphthyl;
[0094] R.sup.14 is defined as above for R.sup.13; and
[0095] R.sup.15 is defined as above for R.sup.1;
[0096] x is independently carbon or nitrogen atom; and
[0097] n is an integer from 1 to 6.
[0098] In some embodiments, the compounds of formulae (I), (II),
(III) or (IV) may comprise R.sup.1-R.sup.10 groups that are
electron donors. Non-limiting examples of electron donor groups are
amines including --N(R.sup.14).sub.2 and --OR.sup.14.
[0099] In some embodiments, the compounds of formulae (I), (II),
(III) or (IV) may comprise R.sup.1-R.sup.10 groups that are
electron acceptors. Non-limiting examples of electron acceptor
groups include --F, --Cl, --Br, --I, --NO.sub.2,
--C(O)(C.sub.1-C.sub.6), --C(O)O(C.sub.1-C.sub.6), --SCN,
--SO.sub.3F and --CN.
[0100] Some illustrative examples and exemplary compounds of
formulae (I) and (II) are listed below in Table 1:
1 TABLE 1 Structure Dopant Complex 7 1 8 2 9 3 10 4 11 5 12 6 13 8
14 9 15 10 16 11 17 12 18 13 19 14 20 15 21 16 22 17 23 18
[0101] Some illustrative examples and exemplary compounds of
formulas (III) and (IV) are listed below in Table 2:
2TABLE 2 Structure Dopant Complex 24 19: n = 2, X = H, Z = H 20: n
= 2, X = H, Z = Cl 21: n = 2, X = H, Z = Br 22: n = 2, X = H, Z = F
23: n = 2, X = H, Z = I 24: n = 2, X = H, Z = CH.sub.325: n = 2, X
= H, Z = t-butyl 26: n = 2, X = H, Z = NO.sub.227: n = 3, #X = H, Z
= H 28: n = 3, X = H, Z = Cl 29: n = 3, X = H, Z = Br 30: n = 3, X
= H, Z = F 31: n = 3, X = H, Z = I 32: n = 3, X = H, Z =
CH.sub.333: n = 3, X = H, Z = t-butyl 34: n = 3, X = H, Z =
NO.sub.235: n = 2, X = CH.sub.3, #Z = H 36: n = 2, X = CH.sub.3, Z
= Cl 37: n = 2, X = CH.sub.3, Z = Br 38: n = 2, X = CH.sub.3, Z = F
39: n = 2, X = CH.sub.3, Z = I 40: n = 2, X = CH.sub.3, Z =
CH.sub.341: n = 2, X = CH.sub.3, Z = t-butyl 42: n = 2, X =
CH.sub.3, Z = NO.sub.243: #n = 3, X = CH.sub.3, Z = H 44: n = 3, X
= CH.sub.3, Z = Cl 45: n = 3, X = CH.sub.3, Z = Br 46: n = 3, X =
CH.sub.3, Z = F 47: n = 3, X = CH.sub.3, Z = I 48: n = 3, X =
CH.sub.3, Z = CH.sub.349: n = 3, X = CH.sub.3, Z = t-butyl 50: n =
3, X = CH.sub.3, #Z = NO.sub.2 25 51: X = H, Z = H 52: X = H, Z =
Cl 53: X = H, Z = Br 54: X = H, Z = F 55: X = H, Z = I 56: X = H, Z
= CH.sub.357: X = H, Z = t-butyl 58: X = H, Z = NO.sub.259: X =
CH.sub.3, Z = H 60: X = CH.sub.3, Z = Cl 61: X = CH.sub.3, #Z = Br
62: X = CH.sub.3, Z = F 63: X = CH.sub.3, Z = I 64: X = CH.sub.3, Z
= CH.sub.365: X = CH.sub.3, Z = t-butyl 66: X = CH.sub.3, Z =
NO.sub.2 26 67: X = H, Y = CH.sub.3, Z = H 68: X = H, Y = CH.sub.3,
Z = Cl 69: X = H, Y = CH.sub.3, Z = Br 70: X = H, Y = CH.sub.3, Z =
F 71: X = H, Y = CH.sub.3, Z = I 72: X = H, Y = CH.sub.3, Z =
CH.sub.373: X = H, Y = CH.sub.3, Z = t-butyl 74: X = H, #Y
=CH.sub.3, Z = NO.sub.275: X = CH.sub.3, Y = CH.sub.3, Z = H 76: X
= CH.sub.3, Y = CH.sub.3, Z = Cl 77: X = CH.sub.3, Y = CH.sub.3, Z
= Br 78: X = CH.sub.3, Y = CH.sub.3, Z = F 79: X = CH.sub.3, Y =
CH.sub.3, Z = I 80: X = CH.sub.3, Y = CH.sub.3, #Z =CH.sub.381: X =
CH.sub.3, Y = CH.sub.3, Z = t-butyl 82: X = CH.sub.3, Y = CH.sub.3,
Z = NO.sub.283: X = CH.sub.3, Y = CN, Z = H 84: X = CH.sub.3, Y =
CN, Z = Cl 85: X = CH.sub.3, Y = CN, Z = Br 86: X = CH.sub.3, Y =
CN, Z = F 87: X = CH.sub.3, #Y = CN, Z = I 88: X = CH.sub.3, Y =
CN, Z = CH.sub.389: X = CH.sub.3, Y = CN, Z = t-butyl 90: X =
CH.sub.3, Y = CN, Z = NO.sub.291: X = H, Y = CN, Z = H 92: X = H, Y
= CN, Z = Cl 93: X = H, Y = CN, Z = Br 94: X = H, Y = CN, Z = F 95:
X = H, Y = CN, #Z = I 96: X = H, Y = CN, Z = CH.sub.397: X = H, Y =
CN, Z = t-butyl 98: X = H, Y = CN, Z = NO.sub.2 27 99: X = H, W =
H, Z = H 100: X = H, W = H, Z = Cl 101: X = H, W = H, Z = Br 102: X
= H, W = H, Z = F 103: X = H, W = H, Z = I 104: X = H, W = H, Z =
CH.sub.3105: X = H, W = H, Z = t-butyl 106: X = H, W = H, Z =
NO.sub.2107: X = #CH.sub.3, W =H, Z = H 108: X = CH.sub.3, W = H, Z
= Cl 109: X = CH.sub.3, W = H, Z = Br 110: X = CH.sub.3, W = H, Z =
F 111: X = CH.sub.3, W = H, Z = I 112: X = CH.sub.3, W = H, Z =
CH.sub.3113: X = CH.sub.3, W = H, Z = t-butyl 114: X = CH.sub.3, #W
= H, Z = NO.sub.2115: X = H, W = CH.sub.3, Z = H 116: X = H, W =
CH.sub.3, Z = Cl 117: X = H, W = CH.sub.3, Z = Br 118: X = H, W =
CH.sub.3, Z = F 119: X = H, W = CH.sub.3, Z = I 120: X = H, W =
CH.sub.3, Z = CH.sub.3121: X = H, W = CH.sub.3, Z = #t-butyl 122: X
= H, W = CH.sub.3, Z = NO.sub.2123: X = CH.sub.3, W = CH.sub.3, Z =
H 124: X = CH.sub.3, W = CH.sub.3, Z = Cl 125: X = CH.sub.3, W =
CH.sub.3, Z = Br 126: X = CH.sub.3, W = CH.sub.3, Z = F 127: X =
CH.sub.3, W = CH.sub.3, Z = I 128: #X = CH.sub.3, W = CH.sub.3, Z =
CH.sub.3129: X = CH.sub.3, W = CH.sub.3, Z = t-butyl 130: X =
CH.sub.3, W = CH.sub.3, Z = NO.sub.2 28 131: X = H, Z = H 132: X =
H, Z = Cl 133: X = H, Z = Br 134: X = H, Z = F 135: X = H, Z = I
136: X = H, Z = CH.sub.3137: X = H, Z = t-butyl 138: X = H, Z =
NO.sub.2139: X = CH.sub.3, Z = H 140: X = CH.sub.3, Z = Cl 141: X =
CH.sub.3, #Z = Br 142: X = CH.sub.3, Z = F 143: X = CH.sub.3, Z = I
144: X = CH.sub.3, Z = CH.sub.3145: X = CH.sub.3, Z = t-butyl 146:
X = CH.sub.3, Z = NO.sub.2 29 147: X = H, Z = H 148: X = H, Z = Cl
149: X = H, Z = Br 150: X = H, Z = F 151: X = H, Z = I 152: X = H,
Z = CH.sub.3153: X = H, Z = t-butyl 154: X = H, Z = NO.sub.2155: X
= CH.sub.3, Z = H 156: X = CH.sub.3, Z = Cl 157: X = CH.sub.3, #Z =
Br 158: X = CH.sub.3, Z = F 159: X = CH.sub.3, Z = I 160: X =
CH.sub.3, Z = CH.sub.3161: X = CH.sub.3, Z = t-butyl 162: X =
CH.sub.3, Z = NO.sub.2 30 163: X = H, Z = H 164: X = H, Z = Cl 165:
X = H, Z = Br 166: X = H, Z = F 167: X = H, Z = I 168: X = H, Z =
CH.sub.3169: X = H, Z = t-butyl 170: X = H, Z = NO.sub.2171: X =
CH.sub.3, Z = H 172: X = CH.sub.3, Z = Cl 173: X = CH.sub.3, #Z =
Br 174: X = CH.sub.3, Z = F 175: X = CH.sub.3, Z = I 176: X =
CH.sub.3, Z = CH.sub.3177: X = CH.sub.3, Z = t-butyl 178: X =
CH.sub.3, Z = NO.sub.2
[0102] Non-limiting examples of bidentate NN-type ligands include
those shown above for dopant complexes 3 and 14 to 18. For example,
NN-type ligands are selected from ligands consisting of at least an
unsubstituted 5-membered or 6-membered ring or substituted
5-membered or 6-membered ring; wherein the substituted 5-membered
or 6-membered ring includes at least one substituent selected from
the groups; a hydrogen, a halogen, a hydroxyl group, an alkyl
group, a cycloalkyl group, an aryl group, an acyl group, an alkoxy,
an acyloxy group, an amino group, an acyl amino group, an aralkyl
group, a cyano group, a carboxyl group, a thio group, a vinyl
group, a styryl group, an aminocarbonyl group, a carbonyl group, an
aranyl group, an aryloxycarbonyl group, a xylyloxycarbonyl group, a
phenoxycarbonyl group or an alkoxycarbonyl group as well as
recognized donor or acceptor groups; wherein the substituents, for
example, an aryl group, may combine together to form a substituted
or unsubstituted, saturated or unsaturated ring with any number of
members. In a preferred embodiment, the transition metal is Pt.
[0103] Non-limiting examples of bidentate NO-type ligands include
those shown above for dopant complexes 67 to 98. For example,
NO-type ligands are selected from ligands consisting of at least an
un-substituted 6-membered or 5-membered ring or substituted
6-membered or 5-membered ring; wherein the substituted 6-membered
or 5-membered ring includes at least one substituent selected from
the groups; a hydrogen, a halogen, a hydroxyl group, an alkyl
group, a cycloalkyl group, an aryl group, an acyl group, an alkoxy,
an acyloxy group, an amino group, an acyl amino group, an aralkyl
group, a cyano group, a carboxyl group, a thio group, a vinyl
group, a styryl group, an aminocarbonyl group, a carbonyl group, an
aranyl group, an aryloxycarbonyl group, a xylyloxycarbonyl group, a
phenoxycarbonyl group or an alkoxycarbonyl group as well as
recognized donor or acceptor groups; wherein the substituents, for
example, an aryl group, may combine together to form a substituted
or unsubstituted, saturated or unsaturated ring with any number of
members. In a preferred embodiment, the transition metal is Pt.
[0104] Non-limiting examples NNNN-type ligands include those shown
above for dopant complexes 1-2 and 4-13. For example, NNNN-type
ligands are selected from ligands consisting of at least an
unsubstituted 5-membered or 6-membered ring or substituted
5-membered or 6-membered ring; wherein those substituted 5-membered
or 6-membered ring includes at least a substituent selected from
the groups; a hydrogen, a halogen, a hydroxyl group, an alkyl
group, a cycloalkyl group, an aryl group, an acyl group, an alkoxy,
an acyloxy group, an amino group, an acyl amino group, an aralkyl
group, a cyano group, a carboxyl group, a thio group, a vinyl
group, a styryl group, an aminocarbonyl group, a carbonyl group, an
aranyl group, an aryloxycarbonyl group, a xylyloxycarbonyl group, a
phenoxycarbonyl group or an alkoxycarbonyl group as well as
recognized donor or acceptor groups; wherein the substituents, for
example, an aryl group, may combine together to form a substituted
or unsubstituted, saturated or unsaturated ring with any number of
members. In a preferred embodiment, the transition metal is Pt.
[0105] Non-limiting examples NOON-type ligands include those shown
above for dopant complexes 19-66 and 99-178. For example, NOON-type
ligands are selected from ligands consisting of at least an
unsubstituted 6-membered or 5-membered ring or substituted
6-membered or 5-membered ring; wherein those substituted 6-membered
or 5-membered ring includes at least a substituent selected from
the groups; a hydrogen, a halogen, a hydroxyl group, an alkyl
group, a cycloalkyl group, an aryl group, an acyl group, an alkoxy,
an acyloxy group, an amino group, an acyl amino group, an aralkyl
group, a cyano group, a carboxyl group, a thio group, a vinyl
group, a ,styryl group, an aminocarbonyl group, a carbonyl group,
an aranyl group, an aryloxycarbonyl group, a xylyloxycarbonyl
group, a phenoxycarbonyl group or an alkoxycarbonyl group as well
as recognized donor or acceptor groups; wherein the substituents,
for example, an aryl group, may combine together to form a
substituted or unsubstituted, saturated or unsaturated ring with
any number of members. In a preferred embodiment, the transition
metal is Pt.
[0106] The present invention is also directed to methods for
preparation of OLEDs that can be fabricated by a vapor deposition
process.
[0107] In one embodiment, OLEDs contain an anode, a
hole-transporting layer, an emissive layer comprising at least one
host material and at least one dopant complex, a hole-blocking
layer, an electron-transporting layer, a charge injection layer and
a cathode.
[0108] Non-limiting examples of an anode useful for OLEDs are
indium-tin-oxide (ITO) and doped polyaniline.
[0109] Non-limiting examples of hole-transporting materials useful
in the present invention are beryllium
bis(2-(2'-hydroxyphenyl)pyridine, 4,440 -bis(carbazol-9-yl)biphenyl
(CBP), N,N-diphenyl-N,N'-bis(1-naphthalene)be- nzidine
(.alpha.-NPB), N,N'-diphenyl-N,N'-bis(2-naphthalene)benzidine
(2-NPB), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD),
4,4',4"-tris(N-3-methylphenyl-N-phenylamino)triphenylamine
(m-TDATA) and tetrakis(diarylamino)-9,9'-spirobifluorenes.
[0110] Non-limiting examples of host materials useful in the
present invention include beryllium
bis(2-(2'-hydroxyphenyl)pyridine, 4,4'-bis(carbazol-9-yl)biphenyl
(CBP), N,N'-diphenyl-N,N'-bis(1-naphthale- ne)benzidine
(.alpha.-NPB), N,N'-diphenyl-N,N'-bis(2-naphthalene)benzidine
(.beta.-NPB), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine
(TPD), 4,4',4"-tris(N-3-methylphenyl-N-phenylamino)triphenylamine
(m-TDATA) tetrakis(diarylamino)-9,9'-spirobifluorenes, beryllium
bis(2-(2'-hydroxyphenyl)pyridine (Bepp.sub.2),
3-phenyl-4-(1'-naphthyl)-5- -phenyl-1,2,4-triazole (TAZ);
2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolin- e (BCP),
1,3-bis(N,N-t-butyl-phenyl)-1,3,4-oxadiazole (OXD7), and
1,3,5-tris(3-methyldiphenylamino)benzene (m-MTDAB).
[0111] In this invention, at least one suitable host material was
employed in an emissive layer together with at least one dopant
complex.
[0112] Non-limiting examples of dopant complexes, of either
geometrical isomers, comprising a transition metal coordinated to
two bidentate NN-type ligands, or two bidentate NO-type ligands, or
a tetradentate NNNN-type ligand, or a tetradentate NOON-type ligand
include those shown for dopant complexes 1-178 in Table 1 and 2
above. In a preferred embodiment, the dopant complexes are selected
from the groups consisting of dopant complexes 1-18, 19, 22, 24-25,
27, 30, 32-33, 35, 38, 40-41, 43, 46, 48-49, 51, 54, 56-57, 59, 62,
64-65, 99, 102, 104-105, 107, 110, 112-113, 115, 118, 120-121, 123,
126, 128-129 and mixtures thereof More preferably, the dopant
complexs are 1, 2, 4, 19, 35, 51, 99 and 104.
[0113] Non-limiting examples of hole-blocking layer suitable for
the present invention include 3,4,5-triphenyl-1,2,4-triazole,
3-(biphenyl-4-yl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole
(TAZ), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and
1,3.5-tris[5-(4-(1,1-dimethylethyl)phenyl)-1,3,4-oxadiazol-2-yl]benzene
(TBOP).
[0114] Non-limiting examples of electron-transporting materials for
the present invention include tris(8-hydroxyquinolato) aluminum
(Alq.sub.3) and
2-(4-biphenylyl)-5-(p-tert-butylphenyl)-1,3,4-oxadiazole.
[0115] Non-limiting examples of charge injection layer suitable for
the present invention include lithium fluoride, cesium fluoride and
lithium benzoate.
[0116] Non-limiting examples of low work function metals for use as
cathode in the present invention include aluminum, potassium,
lithium, magnesium, silver, gold, rubidium, beryllium and
cesium.
[0117] In one preferred embodiment, the, OLED described herein
comprises heterostructures for producing electroluminescence which
contain an anode (ITO glass substance), a hole-transporting layer
(N,N'-diphenyl-N,N'-bis(- 2-naphthalene)benzidine (.beta.-NPB)), a
matrix emissive layer including a host material
4,4'-bis(carbazol-9-yl)biphenyl (CBP)) and an electrophosphorescent
dopant complex as illustrated in Formulae I, II, III or IV herein,
a hole-blocking layer (2,9-dimethyl-4,7-diphenyl-1,10-p-
henanthroline (BCP)), an electron-transporting layer
(tris(8-hydroxyquinolato) aluminum (Alq.sub.3)), a charge injection
layer (lithium fluoride) and a cathode (aluminum metal).
[0118] Preferably, in present invention, OLEDs comprising dopant
complexes as illustrated in Formula I, II, III or IV herein exhibit
red, orange or yellow electroluminescence. The concentration of the
dopant complexes in the emissive layer can range from 0.5 to 8.0
wt. % based on the efficiency of energy conversion between dopant
complexes and host materials and molecular structure of dopant
complexes. However, other concentrations can be used.
[0119] The following examples are set forth to aid in understanding
of the inventions but are not intended to, and should not be
interpreted to, limit in any way the claimed invention.
EXAMPLE 1
[0120] Example 1 shows the synthesis of dopant complex 1. The
tetradentate NNNN-type ligand was prepared according to
modification of literature procedures (see Bacchi et al.,
InorganicaChimica Acta. 342:229, (2003); Male et al., J. Chem.
Soc., Dalton Trans. 2487, (1997)).
[0121] Synthesis of Dopant Complex 1
[0122] Sodium acetate (0.077 g, 0.94 mmol) was suspended in a DMF
(10 mL) solution of bidentate ligand, N,N-Bis-(
1H-pyrrol-2-ylmethylene)-ethane-1- ,2-diamine (0.1 g, 0.47 mmol).
K.sub.2PtCl.sub.4 (0.19 g, 0.47 mmol) dissolved in DMSO (1 mL) was
dropwise added to the suspension at 80.degree. C. dropwise. The
resulting yellow solution turned orange-red after being stirred at
80.degree. C. for 4 hours. After cooling, distilled water (50 mL)
was then added to the orange-red mixture to afford an orange-brown
precipitate. The solid product was filtered and washed with
H.sub.2O (2.times.10 mL) to give an orange-brown solid, which was
then purified by silica gel column chromatography with
CH.sub.2Cl.sub.2 as the eluent. Removal of solvent gave an orange
solid. Orange red crystals were obtained by slow evaporation of
acetonitrile solution of the orange solid.
[0123] Yield: 42 mg (22%). .sup.1H NMR (CDCl.sub.3): .delta.=7.67
(s, 2H, HC.dbd.N), 7.10 (m, 2H, pyrrole), 6.71 (d, J=3.3 Hz, 2H,
pyrrole), 6.29 (dd, J=3.9, 1.8 Hz, 2H, pyrrole), 4.18 (s, 4H,
CH.sub.2). .sup.13C NMR (CDCl.sub.3): .delta.=155.7, 145.4, 137.7,
119.0, 110.7, 59.4. FAB-MS (m-NBA) (m/z): 407 {M.sup.+}. IR (KBr):
v=3107, 3095, 3028, 2998, 2913, 1582, 1570 cm.sup.-1. Anal. Calcd
(%) for C.sub.12H.sub.12N.sub.4Pt: C, 35.38; H, 2.97; N, 13.75.
Found: C, 34.89; H, 2.98; N, 13.29.
EXAMPLE 2
[0124] Example 2 shows the photophysical properties of non-limiting
illustrative emissive materials corresponding to dopant complexes
1, 2 and 4 of the present invention. The absorption and
photoluminescence properties of dopant complexes are provided in
Table 3. UV/vis absorption, excitation and emission spectra of
dopant complexes 1, 2 and 4 are shown in FIGS. 1 to 3 respectively.
The photoluminescence (PL) spectrum is substantially independent of
excitation wavelength from 300 to 450 nm. At room temperature,
strong PL emissions are obtained with quantum yields (.phi.) up to
0.110 in CH.sub.3CN. The emission lifetimes of the dopant complexes
range from 0.57 to 4.25 .mu.s.
3TABLE 3 Physical characterization of dopant complexes 1, 2 and 4.
Dopant .lambda..sub.abs, sol. (nm) .lambda..sub.em, sol..sup.a
.tau. (.mu.s).sup.b Complex [.epsilon. (10.sup.-4 dm.sup.3
mol.sup.-1cm.sup.-1)].sup.a (nm) [.PHI..sub.em, sol.] 1 278 [1.52],
307 [1.47], 566 (max), 4.25 [0.097] 317 [1.56], 372 [sh, 1.34], 613
388 [1.85], 438 [0.45], 459 [sh, 0.36] 2 279 [1.45], 316 [1.64],
563 (max), 3.60 [0.110] 367 [1.36], 383 [1.82], 606, 656 431
[0.48], 448 [sh, 0.41] 4 246 [1.19], 310 [sh, 1.94], 680 (max),
0.57 [0.001] 324 [2.57], 379 [1.99], 740, 822 390 [sh, 1.80], 478
[sh, 1.20], 498 [1.30], 520 [sh, 1.06] .sup.aUV/vis and PL emission
was measured in acetonitrile (CH.sub.3CN) .sup.bLifetime was
measured at peak maximum
[0125] FIG. 1 shows representative U/vis absorption, excitation and
emission spectra of dopant complex 1 in CH.sub.3CN solution. The
solution exhibits strong absorption bands ranged from 278 to 388 nm
(.epsilon.=1.52 to 1.85.times.10.sup.-4 dm.sup.3 mol.sup.-1
cm.sup.-1) and moderately intense absorption bands from 438 to 459
nm (.epsilon.=0.45 to 0.36.times.10.sup.-4 dm.sup.3 mol .sup.-1
cm.sup.-1). Upon excitation at 459 nm, an orange photoluminescence
(PL) emission is obtained with .lambda..sub.max 566 nm and 613 nm.
PL quantum yield (.PHI.) of complex 1 is 0.097.
[0126] FIG. 2 depicts the UV/vis, excitation and emission spectra
of dopant complex 2 in CH.sub.3CN solution. The solution exhibits
several vibronic absorption transitions ranged from 279 to 383 nm
(.epsilon.=1.45 to 1.82.times.10.sup.-4 dm.sup.3 mol.sup.-1
cm.sup.-) and moderately intense absorption bands from 431 to 448
nm (.epsilon.=0.48 to 0.41.times.10.sup.-4 dm.sup.3 mol.sup.-1
cm.sup.-1). The dopant complex 2 exhibits an orange PL emission
bands at .lambda..sub.max 563 nm and 656 nm while the excitation
wavelength is at 431 nm. PL quantum yield (D) of complex 2 is 0.1
10.
[0127] FIG. 3 shows the UV/vis absorption, excitation and emission
spectra of dopant complex 4 in CH.sub.3CN solution. The UV/vis
absorption spectrum shows vibronic absorption transitions ranged
246 to 390 nm (.epsilon.=1.19 to 1.80.times.10.sup.-4 dm.sup.3
mol.sup.-1 cm.sup.-1) and moderately intense absorption bands from
478 to 520 nm (.epsilon.=1.20 to 1.06.times.10.sup.-4 dm.sup.3
mol.sup.-1 cm.sup.-1). The PL spectrum of dopant 4 in CH.sub.3CN
shows a deep red emission at .lambda..sub.max 680 nm and 740 nm. PL
quantum yield ((.PHI.) of complex 4 is 0.001.
EXAMPLE 3
[0128] Example 3 illustrates a non-limiting method for preparing an
OLED of the present invention. The electroluminescent devices were
prepared on patterned indium-tin-oxide (ITO) glass with a sheet
resistance of 20 .OMEGA./square. The glass was cleaned sequentially
in detergent solution, deionized water, ethanol and acetone. After
the wet-cleaning process, the ITO glass was dried at 130.degree. C.
for 1 h and treated in UV ozone cleaner for 10 mins. In the
practice of the present invention of this example, the device
configuration is ITO/NPB (40 nm)/CBP:X wt. % dopant complex as
illustrated in formulae (I), (II), (III) or (IV) (30 nm)/BCP (20
nm)/Alq.sub.3 (30 nm)/LiF (0.5 nm)/Al (150 nm); all of the layers
were grown sequentially by thermal deposition at a deposition rate
of about 0.2 .ANG./sec or about 5 .ANG./sec under a vacuum of
1.times.10.sup.-6 Torr.
[0129] The configuration of OLED in the present invention is
schematically shown in FIG. 4. The device has multiple layers as
shown. In particular, anode layer 410 preferably comprising
indium-tin-oxide is deposited upon substrate layer 405. The
substrate can be glass or other material through which the
electroluminescence can traverse. Hole-transporting layer 415
comprising NPB is placed on top of layer 410. Emissive layer 420
employing CBP host and dopant complex is in contact with
hole-transporting layer 415. A hole-blocking layer 425 containing
BCP is deposited on the emissive layer 420. Adjacent to the
hole-blocking layer 425, an electron-transporting layer 430,
preferably Alq.sub.3, is placed on it. A charge injection layer 435
comprising LiF is then deposited on the layer 430. On top of the
layer 435, a cathode layer 440 is fabricated. Preferably, the
thickness for NPB is 40 nm (hole-transporting layer 415) and the
emissive layer 420 is about 30 nm thick; the hole-blocking layer
425 is 20 nm and electron-transporting layer 430 is 30 nm. The
charge transport layer 435 is 0.5 nm thick and cathode layer 440 is
preferably about 150 nm thick. The emissive area of device is
3.times.3 mm.sup.2, which is defined by overlapping area between
cathode and anode. Although not shown, glass substrate 405 need not
be flat in all embodiments of the invention. In one embodiment, the
glass substrate 405 is shaped, for instance, in a concave shape to
focus the light generated in emissive layer 420, which provides
even greater light intensity in a small region. In another
embodiment, the glass substrate 405 is shaped, for instance, in a
convex shape that spreads the generated light more diffusely.
EXAMPLE 4
[0130] Example 4 shows a red OLED A employing dopant complex 1 as
dopant in a CBP host. The configuration of device A is ITO/NPB (40
nm)/CBP:4 wt. % dopant 1 (30 nm)/BCP (20 nm)/Alq.sub.3 (30 nm)/LiF
(0.5 nm)/Al (150 nm). At 4 wt. % dopant concentration, there was a
red EL emission with a peak maximum at 620 nm corresponding to the
1931 Commission Internationale de L'Eclairage (CIE.sub.--1931)
coordinates of x=0.62 and y=0.38 is obtained at 8V. The maximum
external quantum efficiency (.lambda..sub.ext), luminous efficiency
(.lambda..sub.L), power efficiency (.lambda..sub.P) and brightness
of the device are 6.5%, 9.0 cd/A, 4.0 Im/W and 11 000 cd/m.sup.2,
respectively.
[0131] FIG. 5 shows EL spectra of the OLED A with 4.0 wt. % dopant
1 at different dopant concentrations under 8 V.
[0132] FIG. 6 shows EL spectra of the OLED A with 4.0 wt. % dopant
1 at different applied voltage.
[0133] FIG. 7 depicts V-I-B curve of the OLED A with 4.0 wt. %
dopant 1.
[0134] FIG. 8 shows external quantum efficiency and luminous
efficiency of the OLED A with 4.0 wt. % dopant 1.
[0135] Table 4 shows the EL performance of OLED A with 4.0 wt. %
dopant 1 at different dopant concentrations.
4TABLE 4 EL performance of OLED A with dopant 1 at different dopant
concentrations Dopant V.sub.on B.sub.max .eta..sub.ext,max
.eta..sub.L,max .eta..sub.P,max (wt. %) (V) (cd/m.sup.2) (%) (cd/A)
(lm/W) 0.5 3.5 8 030 4.1 7.1 3.1 1.0 3.4 9 700 5.5 7.4 3.5 2.0 3.5
10 050 5.9 8.6 3.8 4.0 3.2 11 000 6.5 9.0 4.0 6.0 3.3 9 500 5.6 7.5
3.3
EXAMPLE 5
[0136] Example 5 demonstrates an orange OLED B employing dopant
complex 2 as dopant in a CBP host. The device configuration is
ITO/NPB (40 nm)/CBP:5 wt. % dopant 2 (30 nm)/BCP (20 nm)/Alq.sub.3
(30 nm)/LiF (0.5 nm)/Al (150 nm). At 5 wt. % dopant concentration,
there was a orange EL emission with a peak maximum and a shoulder
at 568 and 616 nm corresponding to the 1931 Commission
Internationale de L'Eclairage (CIE.sub.--193 1) coordinates of
x=0.52 and y=0.48 is obtained at 8V. The maximum external quantum
efficiency (.lambda..sub.ext), luminous efficiency
(.lambda..sub.L), power efficiency (.lambda..sub.P) and brightness
of the device are 4.9%, 13.1 cd/A, 5.9 Im/W and 10120 cd/m.sup.2,
respectively.
[0137] FIG. 9 shows the EL spectra of OLED B with 5 wt. % dopant 2
at different dopant concentrations at 8 V.
[0138] FIG. 10 shows the EL spectra of OLEDs B with 5 wt. % dopant
2 at different applied voltages.
[0139] FIG. 11 shows the V-I-B curve of OLED B with 5 wt. % dopant
2.
[0140] FIG. 12 shows the external quantum efficiency and luminous
efficiency of OLED B with 5.0 wt. % dopant 2.
[0141] Table 5 shows the EL performance of OLED B with dopant 2 at
different dopant concentrations.
5TABLE 5 The EL performance of OLED B with dopant 2 at different
dopant concentrations Dopant V.sub.on B.sub.max .eta..sub.ext,max
.eta..sub.L,max .eta..sub.P,max (wt. %) (V) (cd/m.sup.2) (%) (cd/A)
(lm/W) 1.0 3.3 8 200 3.9 10.2 4.8 3.0 3.2 9 150 4.4 11.9 5.3 5.0
2.9 10 120 4.9 13.1 5.9 8.0 3.0 9 250 4.2 11.6 5.1
EXAMPLE 6
[0142] Example 6 shows a yellow OLED C employing dopant complex 19
as dopant in a CBP host. The configuration of device C is ITO/NPB
(40 nm)/CBP:3 wt. % dopant 19 (30 nm)/BCP (20 nm)/Alq.sub.3 (30
nm)/LiF (0.5 nm)/Al (150 nm). At 3 wt. % dopant concentration,
there was a yellow EL emission with a peak maximum at 620 nm
corresponding to the 1931 Commission Internationale de L'Eclairage
(CIE.sub.--1931) coordinates of x=0.49 and y=0.50 is obtained at
8V. The maximum external quantum efficiency (.lambda..sub.ext),
luminous efficiency (.lambda..sub.L), power efficiency
(.lambda..sub.P) and brightness of the device are 2.3%, 6.1 cd/A,
2.4 lm/W and 9370 cd/m.sup.2, respectively.
[0143] FIG. 13 shows the EL spectra of OLED C with 3 wt. % dopant
19 at different dopant concentrations at 8 V.
[0144] FIG. 14 shows the EL spectra of OLED C with 3 wt. % dopant
19 at different applied voltages.
[0145] FIG. 15 shows the V-I-B curve of OLED C with 3 wt. % dopant
19.
[0146] FIG. 16 shows the external quantum efficiency and luminous
efficiency of OLED C with 3.0 wt. % dopant 19.
[0147] Table 6 shows the EL performance of OLED C with dopant 19 at
different dopant concentrations.
6TABLE 6 EL performance of OLED C with dopant 19 at different
dopant concentrations Dopant V.sub.on B.sub.max .eta..sub.ext,max
.eta..sub.L,max .eta..sub.P,max (wt. %) (V) (cd/m.sup.2) (%) (cd/A)
(lm/W) 1.0 3.4 9 050 2.2 5.9 2.3 3.0 3.4 9 370 2.3 6.1 2.4 5.0 3.5
6 120 1.4 3.8 1.4 8.0 3.6 3 460 0.81 2.1 0.85
EXAMPLE 7
[0148] Example 7 shows a yellow OLED D employing dopant complex 51
as dopant in a CBP host. The configuration of device D is ITO/NPB
(40 nm)/CBP:4 wt. % dopant 51 (30 nm)/BCP (20 nm)/Alq.sub.3 (30
nm)/LiF (0.5 nm)/Al (150 nm). At 4 wt. % dopant concentration,
there was a yellow EL emission with a peak maximum and a shoulder
at 550 and 590 nm corresponding to the 1931 Commission
Internationale de L'Eclairage (CIE.sub.--1931) coordinates of
x=0.48 and y=0.52 is obtained at 8V. The maximum external quantum
efficiency (.lambda..sub.ext), luminous efficiency
(.lambda..sub.L), power efficiency (.lambda..sub.P) and brightness
of the device are 11%, 31 cd/A, 14 lm/W and 23000 cd/m.sup.2,
respectively.
[0149] FIG. 17 shows the EL spectra of OLED D with 4 wt. % dopant
51 at different dopant concentrations at 8 V.
[0150] FIG. 18 shows the EL spectra of OLED D with 4 wt. % dopant
51 at different applied voltages.
[0151] FIG. 19 shows the V-I-B curve of OLED D with 4 wt. % dopant
51.
[0152] FIG. 20 shows the external quantum efficiency and luminous
efficiency of
[0153] Table 7 shows the EL performance of OLED D with dopant 51 at
different dopant concentrations.
7TABLE 7 EL performance of OLED D with dopant 51 at different
dopant concentrations Dopant V.sub.on B.sub.max .eta..sub.ext,max
.eta..sub.L,max .eta..sub.P,max (wt. %) (V) (cd/m.sup.2) (%) (cd/A)
(lm/W) 0.5 3.8 4 500 2.0 2.8 1.2 1.0 3.3 11 000 5.4 14 6.2 2.0 2.9
20 500 10 28 13 4.0 2.8 23 000 11 31 14
EXAMPLE 8
[0154] Example 8 shows a red OLED E employing dopant complex 99 as
dopant in a CBP host. The configuration of device E is ITO/NPB (40
nm)/CBP: 1.5 wt. % dopant 99 (30 nm)/BCP (20 nm)/Alq.sub.3 (30
nm)/LiF (0.5 nm)/Al (150 nm). At 1.5 wt. % dopant concentration,
there was a red EL emission with a peak maximum at 636 nm
corresponding to the 1931 Commission Internationale de L'Eclairage
(CIE.sub.--1931) coordinates of x=0.65 and y=0.35 is obtained at
8V. The maximum external quantum efficiency (.lambda..sub.ext),
luminous efficiency (.lambda..sub.L), power efficiency (77P) and
brightness of the device are 9.4%, 11 cd/A, 4.91 m/W and 17900
cd/m.sup.2, respectively.
[0155] FIG. 21 shows the EL spectra of OLED E with 1.5 wt. % dopant
99 at different dopant concentrations at 8 V.
[0156] FIG. 22 shows the EL spectra of OLED E with 1.5 wt. % dopant
99 at different applied voltages.
[0157] FIG. 23 shows the V-I-B curve of OLED E with 1.5 wt. %
dopant 99.
[0158] FIG. 24 shows the external quantum efficiency and luminous
efficiency of OLED E with 1.5 wt. % dopant 99.
[0159] Table 8 shows the EL performance of OLED E with dopant 99 at
different dopant concentrations.
8TABLE 8 EL performance of OLED E with dopant 99 at different
dopant concentrations Dopant V.sub.on B.sub.max .eta..sub.ext,max
.eta..sub.L,max .eta..sub.P,max (wt. %) (V) (cd/m.sup.2) (%) (cd/A)
(lm/W) 0.5 3.2 12 200 6.1 7.2 3.3 1.0 3.2 14 300 7.3 8.5 3.7 1.5
3.1 17 900 9.4 11 4.9 2.5 3.3 15 100 8.1 9.4 3.8 5.0 3.2 10 500 5.5
6.7 2.5
EXAMPLE 9
[0160] Example 9 shows a red OLED F employing dopant complex 104 as
dopant in a CBP host. The configuration of device F is ITO/NPB (40
nm)/CBP: 1.6 wt. % dopant 104 (30 nm)/BCP (20 nm)/Alq.sub.3 (30
nm)/LiF (0.5 nm)/Al (150 nm). At 1.6 wt. % dopant concentration,
there was a red EL emission with a peak maximum at 628 nm
corresponding to the 1931 Commission Internationale de L'Eclairage
(CIE.sub.--1931) coordinates of x=0.64 and y=0.35 is obtained at
8V. The maximum external quantum efficiency (.lambda..sub.ext)
luminous efficiency (.lambda..sub.L), power efficiency
(.lambda..sub.P) and brightness of the device are 6.4%, 7.5 cd/A,
3.4 lm/W and 13600 cd/m.sup.2, respectively.
[0161] FIG. 25 shows the EL spectra of OLED F with 1.6 wt. % dopant
104 at different dopant concentrations at 8 V.
[0162] FIG. 26 shows the EL spectra of OLED F with 1.6 wt. % dopant
104 at different applied voltages.
[0163] FIG. 27 shows the V-I-B curve of OLED F with 1.6 wt. %
dopant 104.
[0164] FIG. 28 shows the external quantum efficiency and luminous
efficiency of OLED F with 1.6 wt. % dopant 104.
[0165] Table 9 shows the EL performance of OLED F with dopant 104
at different dopant concentrations.
9TABLE 9 EL performance of OLED F with dopant 104 at different
dopant concentrations Dopant V.sub.on B.sub.max .eta..sub.ext,max
.eta..sub.L,max .eta..sub.P,max (wt. %) (V) (cd/m.sup.2) (%) (cd/A)
(lm/W) 1.0 3.1 11 300 5.1 6.1 2.7 1.6 3.0 13 600 6.4 7.5 3.4 2.8
3.1 10 100 4.7 5.5 2.5 5.0 3.0 8 500 4.1 4.7 2.2
[0166] The foregoing description of the preferred embodiments of
the present invention has been presented for purposes of
illustration and explanation. The various cited references and
documents in the preceding description are all incorporated herein
by reference in their entirety for all purposes. The description is
not intended to be exhaustive nor to limit the invention to the
precise form disclosed. As is expected, many modifications and
variations will be apparent to those skilled in the art since the
embodiments were chosen and described in order to explain the
principles of the invention and its practical applications, thereby
enabling others skilled in the art to understand the invention. For
example, an advantage of the OLEDs of the present invention is that
the color of the emitted light may be tuned during fabrication by
changing the concentration of the dopant complex. In other
embodiments, the color and/or intensity of the emission of the
OLEDs of the present invention may be changed by the use of
filters, as is known in the art. Various contemplated alternative
embodiments and modifications that are suited to a particular use
are within the scope of the invention. It is intended that the
scope of the invention be defined by the accompanying claims and
their equivalents.
* * * * *