U.S. patent application number 11/759084 was filed with the patent office on 2007-11-08 for polymeric compound and organic luminescence device.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Satoshi Igawa, Jun Kamatani, Shinjiro Okada, Takao Takiguchi, Akira Tsuboyama.
Application Number | 20070257604 11/759084 |
Document ID | / |
Family ID | 26621611 |
Filed Date | 2007-11-08 |
United States Patent
Application |
20070257604 |
Kind Code |
A1 |
Kamatani; Jun ; et
al. |
November 8, 2007 |
POLYMERIC COMPOUND AND ORGANIC LUMINESCENCE DEVICE
Abstract
A main chain-type or side chain-type polymeric compound having a
structure wherein at least one metal complex segment having a
plurality of ligands is introduced into a main chain or a side
chain is provided. In the case where the polymeric compound is the
main chain-type polymeric compound, the metal complex segment has
at least one ligand constituting a polymer main chain of the
polymeric compound and having a carbon atom and oxygen atom bonded
to a metal atom. On the other hand, in the case where the polymeric
compound is the side chain-type polymeric compound, a polymer main
chain thereof has a conjugated structure, preferably a conjugated
double bond. A ligand for the polymeric compound includes a chain
or cyclic ligand, of which a bidentate ligand having an organic
cyclic structure is preferred, and the ligand has at least one
carbon atom or oxygen atom and is bonded to a center metal atom,
preferably iridium, via the carbon atom or oxygen atom. In a case
of forming a luminescence layer by using the polymeric compound as
a luminescent material, a resultant organic luminescence device is
less liable to cause a concentration extinction and is a
high-luminescence efficiency device excellent in stability.
Inventors: |
Kamatani; Jun;
(Kawasaki-shi, JP) ; Okada; Shinjiro;
(Isehara-shi, JP) ; Tsuboyama; Akira;
(Sagamihara-shi, JP) ; Takiguchi; Takao; (Tokyo,
JP) ; Igawa; Satoshi; (Fujisawa-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
26621611 |
Appl. No.: |
11/759084 |
Filed: |
June 6, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10258241 |
Oct 22, 2002 |
7238435 |
|
|
PCT/JP02/08804 |
Aug 30, 2002 |
|
|
|
11759084 |
Jun 6, 2007 |
|
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|
Current U.S.
Class: |
313/504 |
Current CPC
Class: |
H01L 51/0094 20130101;
H01L 51/0035 20130101; H01L 51/0084 20130101; C08G 61/02 20130101;
H01L 51/0059 20130101; C09K 2211/1014 20130101; C09K 2211/188
20130101; H01L 51/0043 20130101; H01L 51/0062 20130101; C09K 11/06
20130101; C09K 2211/1433 20130101; C09K 2211/1466 20130101; C09K
2211/1092 20130101; Y10S 428/917 20130101; C08G 2261/5242 20130101;
C09K 2211/1029 20130101; C08G 2261/374 20130101; C09K 2211/1408
20130101; C08G 83/001 20130101; H01L 51/0085 20130101; C08G
2261/1526 20130101; H01L 51/0081 20130101; C09K 2211/1416 20130101;
H01L 51/5012 20130101; C08G 2261/3142 20130101; H01L 51/004
20130101; H01L 51/0039 20130101; H01L 51/5016 20130101; C09K
2211/1425 20130101; C09K 2211/185 20130101; C08G 2261/312 20130101;
C08G 61/04 20130101 |
Class at
Publication: |
313/504 |
International
Class: |
H01J 1/62 20060101
H01J001/62 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 4, 2001 |
JP |
2001-267233 |
Sep 4, 2001 |
JP |
2001-267110 |
Claims
1-25. (canceled)
26. An organic electroluminescence device comprising: a plurality
of organic electroluminescence elements, disposed in a
two-dimensional direction, each comprising at least an anode, a
cathode, and a polymeric compound disposed between the anode and
the cathode, wherein the polymeric compound has a side chain
containing a metal complex portion which is indirectly bonded to a
main chain of the polymeric compound.
27. A device according to claim 26, wherein the anode and the
cathode are stripe electrodes disposed so that the stripe
electrodes intersect each other, and wherein each of the plurality
of electroluminescence elements is located at an intersection
between the stripe electrodes for the anode and the cathode.
28. An illumination apparatus comprising: an organic
electroluminescence device according to claim 27.
29. An image display apparatus comprising: an organic
electroluminescence device according to claim 27.
30. A device according to claim 26, wherein each of the plurality
of organic electroluminescence devices is connected to an
individual thin film transistor.
31. An illumination apparatus comprising: an organic
electroluminescence device according to claim 30.
32. An image display apparatus comprising: an organic
electroluminescence device according to claim 30.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of copending application Ser.
No. 10/258,241 filed Oct. 22, 2002
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] 1. Technical Field
[0003] The present invention relates to an organic luminescence
device for use in a planar light source, a planar display, etc.
(hereinafter also referred to as an "organic EL
(electroluminescence) device"), and a polymeric compound used
therefor.
[0004] The present invention particularly relates to a luminescence
device using a polymeric compound having a metal complex segment,
more specifically to a luminescence device exhibiting a high
luminescence efficiency and less change with time by using a main
chain or side chain-type polymeric compound having coordinate bond
of a plurality of organic cyclic ligands with a metal, as a
luminescent material containing in its luminescence layer a
luminescence material comprising a metal coordination compound less
liable to cause concentration extinction even when used at a high
concentration.
[0005] 2. Background Art
[0006] An old example of organic luminescence device is, e.g., one
using luminescence of a vacuum-deposited anthracene film (Thin
Solid Films, 94 (1982) 171). In recent years, however, in view of
advantages, such as easiness of providing a large-area device
compared with an inorganic luminescence device, and possibility of
realizing desired luminescence colors by development of various new
materials and drivability at low voltages, an extensive study
thereon for device formation as a luminescence device of a
high-speed responsiveness and a high efficiency, has been
conducted.
[0007] As described in detail in, e.g., Macromol. Symp. 125, 1-48
(1997), an organic EL device generally has a structure comprising
upper and lower two electrodes and (a plurality of) organic
compound layers including a luminescence layer between the
electrodes formed on a transparent substrate.
[0008] For the luminescence layer, aluminum guinolynol complexes (a
representative example thereof is Alq3 shown hereinafter), etc.,
having an electron-transporting characteristic and luminescence
characteristic are used. For a hole-transporting layer, e.g.,
biphenyldiamine derivatives (a representative example thereof is
.alpha.-NPD shown hereinafter), etc., having an electron-donative
characteristic are used.
[0009] These devices have a rectifying characteristic, and when an
electric field is applied between electrodes, electrons are
injected from a cathode into the luminescence layer and holes are
injected from an anode.
[0010] The injected holes and electrons are recombined within the
luminescence layer to form excitons and cause luminescence when
transferred to the ground state.
[0011] In this process, an excited state includes an excited
singlet state and an excited triplet state, and the transition from
the former state to the ground state is called "fluorescence" and
the transition from the latter state to the ground state is called
"phosphorescence". And the substances in these excited states are
called a singlet exciton and a triplet exciton, respectively.
[0012] In most of the organic luminescence devices studied
heretofore, fluorescence caused by the transition from the excited
singlet state to the ground state, has been utilized. On the other
hand, in recent years, devices utilizing phosphorescence via
triplet excitons have been studied.
[0013] Representative published literature may include:
[0014] Article 1: Improved energy transfer in electrophosphorescent
device (D. F. O'Brien, et al., Applied Physics Letters, Vol. 74,
No. 3, p. 422 (1999)); and
[0015] Article 2: Very high-efficiency green organic light-emitting
devices based on electrophosphorescence (M. A. Baldo, et al.,
Applied Physics Letters, Vol. 75, No. 1, p. 4 (1999)).
[0016] In these articles, a structure including 4 lamination layers
as organic layers sandwiched between electrodes has been
principally used. Materials used therein include
carrier-transporting materials and phosphorescent materials.
Abbreviations for the respective materials are as follows.
[0017] Alq3: aluminum quinolinol complex
[0018] .alpha.-NPD:
N4,N4'-di-naphthalene-1-yl-N4,N4'-diphenyl-biphenyl-4,4'-diamine
[0019] CBP: 4,4'-N,N'-dicarbazole-biphenyl
[0020] BCP: 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline
[0021] PtOEP: platinum-octaethylporphyrin complex
[0022] Ir(ppy).sub.3: iridium-phenylpyrimidine complex ##STR1##
##STR2##
[0023] The above-mentioned Articles 1 and 2 both have reported
devices exhibiting a high efficiency, including a hole-transporting
layer comprising .alpha.-NPD, an electron-transporting layer
comprising Alq3, an exciton diffusion-preventing layer comprising
BCP, and a luminescence layer comprising CBP as a host material and
ca. 6% of PtOEP or Ir(ppy).sub.3 as a phosphorescent material
dispersed in mixture therein.
[0024] Such a phosphorescent material is particularly noted at
present because it is expected to provide a high luminescence
efficiency in principle for the following reasons.
[0025] Excitons formed by carrier recombination comprise singlet
excitons and triplet excitons in a probability ratio of 1:3.
Conventional organic EL devices have utilized fluorescence of which
the luminescence efficiency is limited to at most 25%, which has
been an upper limit. However, if phosphorescence generated from
triplet excitons is utilized, an efficiency of at least three times
is expected in principle, and even an efficiency of 100%, i.e.,
four times, can be expected in principle, if a transition owing to
intersystem crossing from a singlet state having a higher energy to
a triplet state is taken into account.
[0026] Articles describing luminescence from the triplet state may
include Japanese Laid-Open Patent Application (JP-A) 11-329739
(organic EL device and production process thereof), JP-A 11-256148
(luminescent material and organic EL device using the same), and
JP-A 8-319482 (organic electroluminescent device).
[0027] However, like a fluorescent-type device, such an organic
luminescence device utilizing above-mentioned phosphorescence is
generally required to be further improved regarding the
deterioration of luminescence efficiency and device stability.
[0028] The reason of the deterioration has not been fully
clarified, but the present inventors consider deterioration occurs
based on the mechanism of phosphorescence.
[0029] In the case where the organic luminescence layer comprises a
host material having a carrier-transporting function and a
phosphorescent guest material, a main process of phosphorescence
via triplet excitons may include unit processes as follows:
[0030] 1. transportation of electrons and holes within a
luminescence layer,
[0031] 2. formation of host excitons,
[0032] 3. excitation energy transfer between host molecules,
[0033] 4. excitation energy transfer from the host to the
guest,
[0034] 5. formation of guest triplet excitons, and
[0035] 6. transition of the guest triplet excitons to the ground
state and phosphorescence.
[0036] Desirable energy transfer in each unit process and
luminescence are caused in competition with various energy
deactivation processes.
[0037] Needless to say, a luminescence efficiency of an organic
luminescence device is increased by increasing the luminescence
quantum yield of a luminescence center material, but it is also an
important factor to increase its concentration. However, if the
concentration of luminescent excitons is too high, the luminescence
intensity is rather lowered as also disclosed in JP-A 05-078655 or
JP-A 05-320633. This phenomenon is known as concentration
extinction or concentration deactivation. The reason for the
phenomenon may be associated with radiationless transition with no
luminescence due to progress of polymer formation reaction between
luminescence center material molecules or those and their
surrounding material molecules, as the above-mentioned competition
reaction. Accordingly, it has been known that there is an
appropriate concentration as a spatial density of luminescence
excitons for improving a luminescence efficiency, irrespective of
fluorescent material or phosphorescent material.
[0038] According to Article 3: Photophysics of metal-organic
.pi.-conjugated polymers, K. D. Ley et al., Coordination Chemistry
Reviews 171 (1998), pp. 287-307, using a main chain-type polymeric
compound comprising a metal complex segment, as a luminescent
material, as a part of a main chain; photoluminescence is measured
by using the following compound and application thereof to an
organic luminescence device is also suggested. TABLE-US-00001
##STR3## P0:x = 0.y = 1.0 P25:x = 0.25.y = 0.75 P10:x = 0.1.y = 0.9
P50:x = 0.5.y = 0.5
[0039] However, according to experience of the present inventors,
the above-mentioned main chain-type polymeric compound has an
unstable C.dbd.O bond contained in Re complex, thus being
considered to be lacking in stability as a compound. Further, the
polymeric compound contains a polymer main chain including triple
bond, thus also being considered to be lacking in
photostability.
[0040] On the other hand, an embodiment using a side chain-type
polymeric compound, represented by a formula shown below, having a
metal complex segment in a polymer side chain as a phosphorescent
material has been described in Article 4: Polymer
electrophosphorescent devices using a copolymer of
Ir(ppy).sub.2-bound 2-(4-Vinylphenyl)pyridine with
N-vinylcarbazole, Change-Lyoul Lee et al., 3rd International
Conference on Electroluminescence of Molecular materials and
Related Phenomena, Program and Abstracts, 0-18, Sep., 5-8, 2001.
##STR4##
[0041] However, when a metal complex segment is introduced into a
polymeric compound skeleton in the case where the metal complex
segment has a conjugated structure, a conjugated (structure)
proportion in the polymeric compound can readily be finally
increased by constituting the polymer main chain skeleton with the
conjugated structure rather than the case of having the metal
complex segment in the side chain. By having a higher conjugated
proportion in the polymeric compound, a higher electroconductivity
is liable to be attained, thus allowing a preparation of a device
possessing a high luminescence efficiency.
DISCLOSURE OF INVENTION
[0042] An object of the present invention is to provide a novel
phosphorescent polymeric compound having a metal complex segment
and an organic luminescence device using the polymeric compound of
a high efficiency and a good stability.
[0043] In order to accomplish the above object, the present
invention provides a polymeric compound of a main chain-type or a
side chain-type comprising at least one metal complex segment in a
main chain or a side chain, wherein
[0044] the main chain-type polymeric compound has a polymer main
chain comprising a ligand of the metal complex segment, said ligand
having a carbon atom or oxygen atom bonded to a metal atom, and
[0045] the side chain-type polymeric compound has a polymer main
chain having a conjugated structure.
[0046] Further, the present invention provides an organic
luminescence device comprising a pair of electrodes disposed on a
substrate, and a luminescence layer disposed therebetween
comprising at least one organic compound, wherein the organic
compound is the above-mentioned polymeric compound.
[0047] The polymeric compound of the present invention includes the
main chain-type polymeric compound and the side chain-type
polymeric compound as described above, and the former is
characterized in that at least one of a plurality of ligands
contained in its metal complex segment constitutes a polymer main
chain that said at least one ligand has a carbon atom or an oxygen
atom bonded to a metal atom of the metal complex segment and, the
latter is characterized in that its metal complex segment is
directly or indirectly bonded to a polymer main chain.
[0048] In the main chain-type polymeric compound, as the ligand
constituting the polymer main chain, it is preferred to use an
organic cyclic ligand but a linear ligand may be used.
[0049] The side chain-type polymeric compound has the conjugated
structure in its main chain skeleton, and the conjugated structure
may preferably be a conjugated double bond. On the other hand, also
in the case of the main chain-type polymeric compound, it is
preferred to have the conjugated structure but the conjugated
structure may be omitted.
[0050] The plurality of ligands contained in the polymeric compound
of the present invention mean molecules, ions or atoms which are
mutually independently bonded to a center metal atom of the metal
complex segment but may preferably be an organic cyclic ligand. The
organic cyclic ligand may preferably be a multidentate ligand,
particularly a bidentate ligand.
[0051] The present inventors have found that the concentration
extinction or the formation of excited polymer is suppressed by
fixing a phosphorescent center material within the main chain-type
or side chain-type polymeric compound at an appropriate
concentration, thus realizing an increase in luminescence
efficiency of the resultant device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 includes schematic sectional views showing structures
of the organic luminescence device according to the present
invention, including: (a) the case of 2-layered structure of
organic film layers; (b) the case of 3-layered structure of organic
film layers; and (c) the case of 4-layered structure of organic
film layers.
[0053] FIG. 2 is a perspective view showing an XY matrix-type
organic EL device.
[0054] FIG. 3 is a view showing drive signal waveforms.
[0055] FIG. 4 is an explanatory view of a matrix-type organic EL
device using TFTs.
BEST MODE FOR PRACTICING THE INVENTION
[0056] Basic device structures according to the present invention
are shown in FIGS. 1(a), (b) and (c).
[0057] As shown in FIG. 1, an organic luminescence device generally
comprises, on a transparent substrate 15, a 50 to 200 nm-thick
transparent electrode 14, a plurality of organic film layers, and a
metal electrode 11 formed so as to sandwich the organic layers.
[0058] FIG. 1(a) shows an embodiment wherein the organic layers
comprise a luminescence layer 12 and a hole-transporting layer 13.
The transparent electrode 14 may comprise ITO, etc., having a large
work function so as to facilitate hole injection from the
transparent electrode 14 to the hole-transporting layer 13. The
metal electrode 11 comprises a metal material having a small work
function, such as aluminum, magnesium or alloys of these elements,
so as to facilitate electron injection into the organic
layer(s).
[0059] The luminescence layer 12 comprises the polymeric compound
according to the present invention. The hole-transporting layer 13
may comprise, e.g., a triphenyldiamine derivative, as represented
by .alpha.-NPD mentioned above, and also a material having an
electron-donative property as desired.
[0060] A device organized above exhibits a current-rectifying
characteristic, and when an electric field is applied between the
metal electrode 11 as a cathode and the transparent electrode 14 as
an anode, electrons are injected from the metal electrode 11 into
the luminescence layer 12, and holes are injected from the
transparent electrode 15. The injected holes and electrons are
recombined in the luminescence layer 12 to form excitons, which
cause luminescence. In this instance, the hole-transporting layer
13 functions as an electron-blocking layer to increase the
recombination efficiency at the boundary between the luminescence
layer 12 and the hole-transporting layer 13, thereby providing an
enhanced luminescence efficiency.
[0061] Further, in the device of FIG. 1(b), an
electron-transporting layer 16 is disposed between the metal
electrode 11 and the luminescence layer 12 in FIG. 1(a). As a
result, the luminescence function is separated from the functions
of election transportation and hole transportation to provide a
structure exhibiting more effective carrier blocking, thus
increasing the luminescence efficiency. The electron-transporting
layer 16 may comprise, e.g., an oxadiazole derivative.
[0062] As shown in FIG. 1(c), a four-layer structure, including a
hole-transporting layer 13, a luminescence layer 12, an exciton
diffusion prevention layer 17 and an electron-transporting layer
16, successively from the side of the transparent electrode 14 as
an anode, is also a desirable form.
[0063] The PC of the present invention refers to a compound having
a number-average molecular weight (Mn) of at least 2,000 and has at
least one metal complex segment in its molecule constituting a
polymer main chain or directly or indirectly bonded to a polymer
main chain and also emits phosphorescence. Its lowest excited state
is believed to be an MLCT* (metal-to-ligand charge transfer)
excited state or .pi.-n* excited state in a triplet state, and
phosphorescence is caused at the time of transition from such an
excited state to the ground state.
[0064] The polymeric compound of the present invention exhibited a
high phosphorescence yield of from 0.15 to 0.9 and a short
phosphorescence life of 0.1-100 .mu.sec.
[0065] If the phosphorescence life is too long, an energy
saturation state is caused to occur thereby remarkably lowering
luminescence efficiency. Long phosphorescence life is not desired
in a luminescence device. Further, abundant presence of molecules
in a triplet excited state awaiting luminescence is therefore
subject to various competition reactions as described above, thus
leading to a reduction in luminescence efficiency. Particularly,
there arises a problem of a lowering in luminescence efficiency
when a current passing through a device has a high density.
[0066] The present invention is characterized by a luminescent
material for the organic EL device exhibiting properties such that
the above-mentioned concentration extinction is minimized to
provide stable luminescence and to provide a high phosphorescence
yield and a relatively short phosphorescence life in a temperature
range of -20.degree. C. to (+) 60.degree. C. being a practical
operation temperature of the organic luminescence device. The
luminescence material is provided by fixing a phosphorescent
material in a polymer in a form of a metal complex segment at a
certain proportion.
[0067] Further, this polymeric material has various emission
wavelengths depending on a difference in structure of the metal
complex segment, so that it becomes possible to provide a material
having a broad emission wavelength and allow preparation of a
device exhibiting a good luminescent characteristic by
incorporating a plurality of metal complex segments including
ligands or metal atoms different in structure into a polymer main
chain. For this reason, the polymeric compound of the present
invention may preferably be a copolymer.
[0068] Examples of the center metal atom contained in a metal
complex segment of the polymeric compound of the present invention
may include, e.g., platinum (Pt), rhodium (Rh), ruthenium (Ru),
iridium (Ir), osmium (Os), gold (Au), palladium (Pd), copper (Cu),
and cobalt (Co), preferably platinum (Pt), rhodium (Rh), ruthenium
(Ru) and iridium (Ir), particularly preferably iridium (Ir). The
center metal atom may preferably be bonded to at least one carbon
atom or oxygen atom contained in each ligand.
[0069] Specific examples of the ligand constituting the metal
complex segment may preferably include those shown below, such as
phenylpyridine, thienylpyridine, phenylisoquinoline, acetylacetone,
picolinic acid, derivatives having these skeletons, derivatives
having a phenyl group skeleton, and derivatives having a pyridine
skeleton. Incidentally, hydrogen atom in each structural formula
may be substituted with another atom or group. Further, non-bonding
linkage indicates methyl group. ##STR5## ##STR6##
[0070] Further, in the present invention, it is also possible to
use, e.g., a polymeric compound having a plurality of different
metal complex segments by appropriately changing the species and
the number of metal atom(s) and ligands constituting the metal
complex segment. Alternatively, it is also possible to use at least
one other compound in mixture with the polymeric compound of the
present invention.
[0071] Further, the polymeric compound of the present invention can
be in mixture of plural species with a compound ordinarily used as
a carrier transport layer, thus allowing preparation of a device
having a broad emission wavelength or a device of a higher
luminescence efficiency. Further, it is also possible to provide
improved film-forming properties such as prevention of
precipitation of a crystal at the time of device preparation.
[0072] Of the above-mentioned polymer compounds, examples may
include those shown below including: PPV
(polyparaphenylenevinylene) and its derivatives such as RO-PPV,
CN-PPV, DMOS-PPV and MEH-PPV; PAT (polyalkylthiophene) and its
derivatives such as PEDOT, PCHMT, POPT, PTOPT, PDCHT and PCHT; PPP
and its derivatives such as RO-PPP and FP-PPP; PDAF
(polydialkylfluorenone); PVK (polyvinylcarbazole); polyacetylene
derivatives such as PPA, PDPA and PAPA; polysilane-based sigma
((.sigma.)-conjugation system polymers such as PDBS, PDHS, PMPS and
PBPS; polysilol and triphenylamine-based polymers such as TPDPES
and TPDPEK. ##STR7## ##STR8##
[0073] Next, the polymeric compound of the present invention is
roughly classified into two types as described above including:
[0074] 1) main chain-type polymeric compound (the case where a
ligand of a metal complex segment is directly introduced into a
polymer main chain), and
[0075] 2) side chain-type polymeric compound (the case where a
metal complex segment is directly or directly bonded to a polymer
main chain).
[0076] First, the main chain-type polymeric compound of 1) will be
described. Its synthesis method may be roughly classified into two
processes shown below for:
[0077] a) polymer reaction-type polymeric compound, and
[0078] b) metal complex monomer-type polymeric compound.
[0079] Further, similar processes may also be adopted when a
compound containing a plurality of metal complex segments at the
same time is prepared.
[0080] Hereinbelow, general synthesis examples of the objective
main chain-type polymeric compound in the present invention are
shown below. Hereinafter, A, B and C respectively represent a
monomer or divalent organic group having no coordination site; L
represents a coordination atom or group; and M represents a metal
ion or metal complex. Incidentally, A, B and C may be omitted, and
an entire polymer main chain may be constituted by L.
[0081] a) Polymer reaction-type polymeric compound ##STR9##
[0082] b) Metal complex monomer-type polymeric compound
##STR10##
[0083] Then, the side chain-type of 2) will be described. Examples
of a general formula of the side chain-type polymeric compound of
the present invention are shown below. Further, the polymeric
compound of the present invention may be prepared through a
copolymerization with another polymeric compound precursor. A main
chain of the polymeric compound is represented by
--(X).sub.n--(Y).sub.m-- segment in the following formula, and a
side chain of the polymeric compound is represented by
-Z-L.sub.1-M-L.sub.2(L.sub.3) segment. ##STR11##
[0084] In the formula, X is an electroconductive group such as
vinylene, phenylene, phenylenevinylene or thiophene. Y may
desirably be a polymer unit having an electroconductive group such
as phenylenevinylene, thiophene or fluorene but may be a single
bond. Further, Y does not have a side chain. Although Z is not
particularly limited, Z may be an alkylene group such as methylene
or ethylene, an aromatic group such as phenylene, a combination of
these groups, or a single bond. M is a center metal and may be
selected from the group consisting of platinum (Pt), rhodium (Rh),
ruthenium (Ru), iridium (Ir), osmium (Os), gold (Au), palladium
(Pd), copper (Cu), and cobalt (Co), particularly be platinum,
rhodium, ruthenium or iridium. L.sub.1 represents a group having at
least a carbon-metal coordination bond or oxygen-metal coordination
bond, and examples thereof may include the above-mentioned ligands;
picolinic acid; derivatives having these skeletons; derivatives
having a phenyl group skeleton; derivatives having pyridine
skeleton; and .beta.-diketones. Although L.sub.2 and L.sub.3 are
not particularly limited, L.sub.2 and L.sub.3 may desirably be a
bidentate ligand, such as the above-mentioned ligands; picolinic
acid; derivatives having these skeletons; derivatives having a
phenyl skeleton; derivatives having pyridine skeletons; and
.beta.-diketones. In the case where the metal has a coordination
number of 4, L.sub.3 may be omitted. Further, L.sub.2 and L.sub.3
may be the same group or different groups. The letters m and n
represent a polymerization degree and may be determined
appropriately in view of a luminescence efficiency or an
electroconductivity, with the provisio that n is not 0.
[0085] Further, as shown in the following general formula, the side
chain-type polymeric compound may contain a plurality of metal
atoms or ligands in its molecule. In the following formula, a main
chain of the polymeric compound of the present invention is
represented by --(X1).sub.k--(X2).sub.1-- segment, and a side chain
is represented by -Z.sub.1-L.sub.11-M.sub.1-L.sub.12(L.sub.13) and
-Z.sub.2-L.sub.21-M.sub.2-L.sub.22(L.sub.2). ##STR12##
[0086] In the above general formula, X1 and X2 correspond to X
described above, Z.sub.1 and Z.sub.2 correspond to Z described
above, M.sub.1 and M.sub.2 correspond to M described above,
L.sub.11 and L.sub.12 correspond to L.sub.1 described above,
L.sub.12 and L.sub.22 correspond to L.sub.2 described above,
L.sub.13 and L.sub.23 correspond to L.sub.3 described above, and k
and 1 correspond to m and n described above, respectively.
[0087] In the case where the above-mentioned main chain-type and
side chain-type polymer compounds are synthesized, structures of
reaction products are not restricted to the general formulas
described above because bonding to the above-mentioned monomers or
metal complex segments may be expected to assume various bonding
(linkage) manners. For example, it is also considered that a metal
atom is bonded or linked to a ligand constituting another recurring
unit, or a crosslinked structure is formed between plural
molecules. Similarly, the polymerization degree varies depending on
production conditions, so that it is also possible to change a
resultant number-average molecular weight from several thousands to
several millions.
[0088] However, in view of preparation of the organic luminescence
device, it is necessary to form a luminescence layer comprising the
polymeric compound on a substrate. In this instance, if the
molecular weight is too small, wettability at the time of
(wet-)coating is undesirably liable to be impaired or peeling of
film is undesirably liable to occur after the coating. On the other
hand, if the molecular weight exceeds a million, the polymeric
compound is not readily dissolved in a solvent used in the coating
step to be precipitated, or an excessively high viscosity of a
solution impairs a coating performance in some cases.
[0089] Accordingly, the polymeric compound of the present invention
may generally preferably have a number-average molecular weight of
2,000-1,000,000, and may readily be treated as a compound. A
further preferred range is from 3,000 to 100,000.
[0090] Further, the polymeric compound of the present invention can
be used together or in mixture with another polymeric compound.
Such other polymeric compound preferably includes a compound
similar to the polymeric compound of the present invention, a
polymeric compound having a carrier-transporting performance, such
as PVK or PPV as described above, and a polymeric compound capable
of improving film-forming properties. Such another polymeric
compound may be used in mixture with the polymeric compound of the
present invention to form a single layer or used together with the
polymeric compound of the present invention for separate layers in
lamination.
[0091] Synthesis schemes of the main chain-type and side chain-type
polymeric compounds of the present invention will be specifically
shown below by taking those for iridium coordination-polymeric
compound as an example.
Main Chain-Type Polymeric Compound
[0092] A synthesis process of the polymeric compound having a
polymer main chain into which a ligand of a metal complex segment
is introduced may include a process wherein the polymer main chain
is formed in advance and is reacted with a metal complex and a
process wherein a polymer precursor to which a metal complex is
bonded is subjected to a copolymerization with monomer(s).
SYNTHESIS EXAMPLE 1
[0093] ##STR13##
[0094] Pd(PPh.sub.3).sub.4: tetrakis(triphenylphosphine)palladium
##STR14##
[0095] When the final compound is viewed with respect to Ir metal
as a center, the Ir metal is directly bonded to a nitrogen atom of
a pyridine ring and a carbon atom of a benzene ring, in a bidentate
ligand constituting a polymer main chain. Further, the Ir metal is
found to be similarly bonded to a pyridine ring and a benzene ring
of each of the two bidentate ligands.
[0096] (In the above equation, a ratio between two recurring units
depends on concentrations of [Ir(L).sub.2Cl.sub.2] or
Ir(L).sub.2acac and reaction conditions, so that it is possible to
control a recurring manner of the two recurring units.)
SYNTHESIS EXAMPLE 2
[0097] ##STR15##
[0098] (In the above equation, a ratio between two recurring units
depends on concentrations of monomers a and b during the reaction
and reaction conditions, so that it is possible to control a
recurring manner of the two recurring units.) ##STR16##
[0099] (In the above equation, a ratio among three recurring units
depends on starting materials, concentrations of
[Ir(L).sub.2Cl.sub.2] or Ir(L).sub.2acac used in the reaction and
reaction conditions, so that it is possible to control a recurring
manner of the two recurring units. A similar situation is held with
respect to the following compound examples.
SYNTHESIS EXAMPLE 3
[0100] ##STR17##
SYNTHESIS EXAMPLE 4
[0101] ##STR18##
SYNTHESIS EXAMPLE 5
[0102] ##STR19##
SYNTHESIS EXAMPLE 6
[0103] ##STR20## Side Chain-Type Polymeric Compound
[0104] Next, specific examples of the polymeric compound having a
metal complex segment directly or indirectly bonded to its polymer
main chain according to the present invention are shown below.
[0105] Herein, polymeric compounds having a polymer side chain into
which an iridium complex, rhodium complex or platinum complex
having a ligand comprising phenyl pyridine, etc., is introduced as
the metal complex segment. ##STR21## ##STR22## ##STR23##
[0106] Compound examples of the polymeric compound of the present
invention are shown hereinabove. Incidentally, structures of the
above examples of various polymeric compounds vary depending on
reaction conditions such as starting materials, concentrations and
reaction temperatures, thus being not necessarily constant. Herein,
representative examples are merely shown and accordingly the
present invention is not restricted to these examples.
[0107] Further, even when the metal atom is platinum (Pt), rhodium
(Rh), ruthenium (Ru), osmium (Os), gold (Au), palladium (Pd),
copper (Cu) or cobalt (Co), a similar effect can be expected.
[0108] Further, in the organic luminescence device of the present
invention, a lamination structure as shown in FIG. 1(b) principally
as an organic luminescence layer is preferred but, it is possible
to use the polymeric compound of the present invention and a
compound having a transportability of carrier, such as electron
and/or hole, formed into layers in lamination. Further, it is also
possible to constitute a luminescence device by forming a single
organic layer (luminescence layer) with a mixture of the polymeric
compound of the present invention and a compound having a carrier
transportability for an electron and/or a hole between electrodes
although the structure thereof is not shown. This structure is
simpler than the structure shown in FIG. 1, thus allowing an
enhanced productivity of the luminescence device.
[0109] Hereinbelow, the present invention will be specifically
described by enumerating Examples. In the following Examples, an
iridium (Ir) complex will be principally exemplified as a metal
complex for explaining the effect of the present invention.
EXAMPLE 1
Synthesis of Polymeric Compound 5
[0110] A polymeric Ir metal complex compound according to the
present invention was obtained through a process shown hereinafter.
##STR24##
[0111] In a 20 ml-round bottomed flask (or Kjeldahl flask) aerated
with nitrogen, a raw-material compound 1 (2.0 mM, 1.29 g) and a
raw-material compound 2 (2.0 mM, 0.47 g) respectively sufficiently
purified were placed and thereto, a mixture solution of 8 ml of
tetrahydrofuran (THF) and 6 ml of 2M-K.sub.2CO.sub.3 aqueous
solution was added and mixed, followed by sufficient stirring for
dissolution in a nitrogen atmosphere. To the solution,
Pd(PPh.sub.3).sub.4 (17.4 mg, 0.0015 mM) was added, followed by
refluxing for 48 hours. After the reaction, methanol was added to
the mixture solution to precipitate a reaction product. The
precipitated product was washed with water and further subjected to
Soxhlet's extraction with acetone for 24 hours to obtain a yellow
powdery intermediate compound 3 (0.79 g, Yield: 85%, Mn=11,000, Mw
(weight-average molecular weight)/Mn=2.1 (in TFT, polystyrene
standard)). ##STR25##
[0112] In a 100 ml-round bottomed flask, 50 ml of dehydrated
glycerol was placed and aerated with nitrogen for 2 hours at
130.degree. C. Thereafter, to the glycerol, the above-prepared
compound 3 (0.47 g, 1.0 mM) and compound 4 (0.13 g, 0.2 mM) were
added, followed by stirring for 18 hours under heating. The
reaction product was cooled to room temperature and poured into 300
ml of 1N-HCl (hydrochloric acid). A resultant precipitate was
recorded by filtration and washed with water. The precipitate was
dissolved in chloroform, followed by removal of an insoluble matter
by filtration. Thereafter, the resultant solution was subjected to
Soxhlet's extraction with acetone for 24 hours to obtain 0.50 g of
a yellow powder of an objective main chain-type polymeric compound
5 (Ir metal complex) according to the present invention (Mn=13,000,
Mw/Mn=2.1 (in TFT, polystyrene standard)).
[0113] With respect to this polymeric compound, a luminescence life
was examined in the following manner.
[0114] The polymeric compound was dissolved in chloroform and
spin-coated onto a quartz substrate in a thickness of ca. 0.1 .mu.m
to prepare a measurement sample. The sample was exposed to
pulsative nitrogen laser light at an excitation wavelength of 337
nm at room temperature by using a luminescence life meter (made by
Hamamatsu Photonics K.K.). After completion of the excitation
pulses, the decay time of luminescence intensity was measured.
[0115] When an initial luminescence intensity is denoted by 10, a
luminescence intensity after t(sec) is expressed according to the
following formula with reference to a luminescence life .tau.(sec):
I=I.sub.0exp(-t/.tau.).
[0116] The polymeric compound 5 showed a phosphorescent
characteristic and a phosphorescence life of at most 10 .mu.sec,
thus having a shorter life among phosphorescent substances.
EXAMPLE 2
[0117] As another main chain-type polymeric compound, a polymeric
compound 7 was synthesized and evaluated in the same manner as in
Example 1 except that the compound 3 and the compound 4 used in
Example 1 and the following compound 6 were used as starting (raw)
materials and mixed in an equivalent mole ratio. ##STR26##
[0118] The polymeric compound 7 of this example is comprised of two
species of Ir complex structures in a polymer main chain.
Incidentally, an arrangement of these complex structures and a
density of Ir complex are different depending on reaction
conditions etc. Accordingly, the structural formula (of the
polymeric compound 7) is not restricted to the above structural
formula.
[0119] The polymeric compound 7 had a phosphorescent characteristic
and, a phosphorescent life thereof measure according to the
above-mentioned manner was 10 .mu.sec or below, thus resulting in a
shorter life among phosphorescent substances.
EXAMPLE 3
[0120] An organic luminescence device having 3 organic layers (12,
13, 16) as shown in FIG. 1(b) was prepared by using the compound
obtained in the above-mentioned Example 2 and a device
characteristic thereof was evaluated. First, an alkali-free glass
sheet was used as a transparent substrate 15 and a 100 nm-thick
indium tin oxide (ITO) film was formed thereon by sputtering and
patterned as a transparent electrode 14.
[0121] On the transparent electrode 14, a polymeric film comprising
PEDOT and PSS (mole ratio of 1:1) represented by the following
structural formulas was formed as a hole transport layer 13 in a
thickness of 40 nm (after drying) by spin coating and thereon, a
0.5%-chloroform solution of the polymeric compound 7 prepared in
the above-mentioned Example 2 was spin-coated plural times and
dried in an oven for 60 min. at 60.degree. C., thus obtaining a 30
nm-thick luminescence layer 12. Further thereon, as an electron
transport layer 16, a compound represented by Bphen shown below was
subjected to resistance heating (vacuum) deposition at a vacuum of
10.sup.-4 Pa to obtain an organic film in a thickness of 40 nm.
##STR27##
[0122] On this electron transport layer 16, a layer of potassium
fluoride (KF) was disposed in a thickness of 5 nm as an
undercoating layer for a metal electrode layer 11.
[0123] Further, on the undercoating layer, a 100 nm-thick aluminum
(Al) film was vacuum-deposited as a metal electrode 11 and
patterned in a shape having an electrode area (effective display
area) of 3 mm.sup.2 disposed opposite to the transparent electrode
14.
[0124] The characteristics of the organic luminescence device were
measured by using a micro-current meter ("4140B", made by
Hewlett-Packard Corp.) for a current-voltage characteristic and
"BM7" (made by Topcon K.K.) for an emission luminance. The device
using the (polymeric) compound of this example showed a good
rectification characteristic. Further, when the organic
luminescence device was supplied with a voltage of 15 V (volts)
between upper and lower electrodes, luminescence from the organic
luminescence device was confirmed. In this Example 3, light of two
emission wavelengths (550 nm and 620 nm) resulting from the two
species of Ir complexes which might be attributable to the compound
4 and the compound 6 was confirmed.
[0125] Next, in order to confirm that the luminescence was
phosphorescence, each of the polymeric compounds prepared in
Examples 1 and 2 was dissolved in chloroform, and the solution
divided into two solutions, which were aerated with oxygen and
nitrogen, respectively. Each of the oxygen-aerated solution and the
nitrogen-aerated solution was subjected to photoirradiation for
comparison of photoluminescence. As a result, substantially no
luminescence attributable to the iridium complex was recognized
with respect to the oxygen-aerated solution, whereas
photoluminescence was confirmed with respect to the
nitrogen-aerated solution. From these results, the polymeric
compounds of the present invention were confirmed to be a
phosphorescent polymeric compound.
[0126] Further, in contrast with a fluorescent material generally
showing a luminescence life of several nsec to several tens of
nsec, the polymeric compounds of the present invention all
exhibited a phosphorescence life of 100 nsec or longer.
EXAMPLE 4
[0127] In order to evaluate a device life, 3 types of devices were
prepared in Examples 4 and 5 and Comparative Example 1 and actually
driven at room temperature to measure their luminance half times
(periods).
[0128] In Example 4, an organic luminescence device was prepared
under the same conditions as in Example 3 except that the polymeric
compound 5 prepared in Example 1 was used and the following layer
structure was adopted.
[0129] Hole transport layer 13 (40 nm):PEDOT:PPS (mole ratio
1:1)
Electron Transport Layer 16 (60 Nm):Bphen
[0130] To the device, a drive waveform shown in FIG. 3 was applied
to measure a change in emission luminance at room temperature to
determine a time of requiring a decrease of an initial luminance to
1/2 thereof.
EXAMPLE 5
[0131] An organic luminescence device was prepared and evaluated in
the same manner as in Example 3 except that a layer of a mixture of
the polymeric compound 5 prepared in Example 4 as a polymeric
compound with PVK (polyvinyl carbazole) shown below as a polymeric
compound containing no metal complex segment in a weight ratio of
1:10 was used as the luminescence layer. ##STR28##
COMPARATIVE EXAMPLE 1
[0132] An organic luminescence device was prepared and evaluated in
the same manner as in Example 3 except that the luminescence layer
was formed by using a film of a mixture prepared by dispersing an
iridium-ppy complex (Ir(ppy).sub.3) in the above-mentioned
polymeric compound 3 having no metal complex segment in a weight
ratio of 1:10, as the luminescent material.
[0133] The results of Example 4, Example 5 and Comparative Example
1 are shown inclusively in Table 1.
[0134] As a result of a current-passing durability test of the
devices using the respective polymeric compounds, it has been found
that the devices using the polymeric compounds of the present
invention clearly exhibited longer luminance half times than the
device using the conventional luminescent material, thus allowing a
device having a high durability attributable to stability of the
luminescent materials of the present invention. TABLE-US-00002
TABLE 1 Luminescent material for Luminescence half time
luminescence layer (hours) Example 4 Polymeric compound 5 700
Example 5 Mixture of polymeric 650 compound 5 with PVK (1:10)
Comparative Ir(ppy).sub.3 with polymeric 350 Example 1 compound 3
(1:10)
EXAMPLE 6
[0135] A polymeric compound 9 having an iridium complex in a
polymer side chain was obtained through the following reaction.
##STR29## ##STR30## Synthesis of Compound 2 and Compound 3
[0136] Compound 2 and Compound 3 as intermediates of an iridium
complex were synthesized by using an iridium chloride and phenyl
pyrimidine as raw (starting) materials with reference to Sergey
Lamansky et al., "Inorg. Chem.", 40, pp. 1704-(2002).
Synthesis of Compound 5
[0137] In a 100 ml-round bottomed flask, 50 ml of dehydrated
glycerol was placed and nitrogen-aerated for 2 hours at 130.degree.
C. Thereafter Compound 3 (1.2 g, 2 mM) and Compound 4 (1.2 g, 2.5
mM) were added to the glycerol, followed by stirring under heating
in a nitrogen stream for 18 hours. The reaction product was cooled
to room temperature and poured into 600 ml of 1N-hydrochloric acid
to recover a precipitate by filtration, followed by washing with
water. Thereafter, the precipitate was purified by preparation HPLC
(high performance liquid chromatography) to obtain 300 mg of a
powdery six-coordinate iridium compound 5.
Synthesis of Compound 7
[0138] In a 20 ml-round bottomed flask aerated with nitrogen,
Compound 5 (300 mg, 0.22 mM) and Compound 6 (42 mg, 0.22 mM) were
placed and thereto, 2 ml of toluene, 1 ml of ethanol and 2 ml of
2M-K.sub.2CO.sub.3 aqueous solution were added for mixing, followed
by sufficient stirring in a nitrogen atmosphere. Thereafter, 40 mg
(0.035 mM) of Pd(PPh.sub.3).sub.4 was added to the mixture,
followed by refluxing for 8 hours. After the reaction, the mixture
wa subjected to extraction by addition of toluene and water and the
organic layer was dried with magnesium sulfate, followed by
purification by alumina chromatography to obtain 150 mg of powdery
Compound 7.
Synthesis of Polymeric Compound 9
[0139] In a 20 ml-round bottomed flask aerated with nitrogen, 150
mg (0.2 mM) of sufficiently purified Compound 7 and 129 mg (0.2 mM)
of a polymeric monomer 8 were placed and thereto, 1 ml of
tetrahydrofuran (THF) and 0.6 ml of 2M-K.sub.2CO.sub.3 aqueous
solution were added for mixing. After the mixture was sufficiently
stirred in a nitrogen atmosphere, 1.73 mg (0.00015 mM) of
Pd(PPh.sub.3).sub.4 was added to the mixture, followed by refluxing
for 48 hours. After the reaction, the mixture liquid was
reprecipitated in methanol and washed with water, followed by
Soxhlet's extraction with acetone for 24 hours to obtain 195 mg of
powdery side chain-type polymeric compound 9 of the present
invention.
[0140] Discrimination between fluorescence and phosphorescence with
respect to a luminescence was performed in the same manner as in
Example 3 by using the above-prepared polymeric compound 9. As a
result, substantially no luminescence attributable to the iridium
complex was recognized with respect to the oxygen-aerated solution,
whereas photoluminescence was confirmed with respect to the
nitrogen-aerated solution. From these results, the polymeric
compound 9 of the present invention was confirmed to exhibit a
phosphorescent characteristic.
[0141] The polymeric compound 9 had a phosphorescent life, as a
result of measurement according to the above-mentioned manner was
10 .mu.sec or below, thus resulting in a shorter life among
phosphorescent substances.
EXAMPLE 7
[0142] An organic luminescence device having 3 organic layers as
shown in FIG. 1(b) was prepared by using the polymeric compound 9
obtained in Example 1 and a device characteristic thereof was
evaluated. An alkali-free glass sheet was used as a transparent
substrate 15 and a 100 nm-thick indium tin oxide (ITO) film was
formed thereon by sputtering and patterned as a transparent
electrode 14. On the transparent electrode 14, a polymeric film
comprising PEDOT and PSS (mole ratio of 1:1) represented by the
following structural formulas was formed as a hole transport layer
13 in a thickness of 40 nm by spin coating and thereon, a
0.5%-chloroform solution of the polymeric compound 9 prepared in
Example 1 was spin-coated plural times and dried in an oven for 60
min. at 60.degree. C., thus obtaining a 30 nm-thick luminescence
layer 12. Further thereon, as an electron transport layer 16, a
compound represented by Bphen shown below was subjected to
resistance heating (vacuum) deposition at a vacuum of 10.sup.-4 Pa
to obtain an organic film in a thickness of 40 nm. ##STR31##
[0143] On this electron transport layer 16, a layer of potassium
fluoride (KF) was disposed in a thickness of 5 nm as an
undercoating layer for a metal electrode layer 11.
[0144] Further, on the undercoating layer, a 100 nm thick aluminum
(Al) film was vacuum-deposited as a metal electrode 11 and
patterned in a shape having an electrode area (effective display
area) of 3 mm.sup.2 disposed opposite to the transparent electrode
14.
[0145] The characteristics of the organic luminescence device were
measured by using a micro-current meter ("4140B", made by
Hewlett-Packard Corp.) for a current-voltage characteristic and
"BM7" (made by Topcon K.K.) for an emission luminance. The device
using the (polymeric) compound of this example showed a good
rectification characteristic. Further, when the organic
luminescence device was supplied with a voltage of 15 V (volts)
between upper and lower electrodes, luminescence from the organic
luminescence device was confirmed. Further, this luminescence was
similar to photoluminescence of the luminescent material used in
this example measured in a toluene solution, so that it was
confirmed that the luminescence was that emitted from the
luminescence material being the iridium complex.
[0146] Further, when the luminescence characteristic of the organic
luminescence device of this example was measured, in contrast with
a fluorescent material generally showing a luminescence life of
several nsec to several tens of nsec, the device exhibited a
phosphorescence life of 2 .mu.sec or shorter.
EXAMPLE 8
[0147] Compound 10 was synthesized in the same synthesis process as
in Example 6, and a side chain-type polymeric compound 11 of the
present invention was synthesized in the following process.
[0148] In a 20 ml-round bottomed flask aerated with nitrogen, 75 mg
(0.1 mM) of sufficiently purified Compound 7 and 81 mg (0.1 mM) of
Compound 10 and 129 mg (0.2 mM) of Compound 8 were placed and
thereto, 1 ml of tetrahydrofuran (THF) and 0.6 ml of
2M-K.sub.2CO.sub.3 aqueous solution were added for mixing. After
the mixture was sufficiently stirred in a nitrogen atmosphere, 1.73
mg (0.00015 mM) of Pd(PPh.sub.3).sub.4 was added to the mixture,
followed by refluxing for 48 hours. After the reaction, the mixture
liquid was reprecipitated in methanol and washed with water,
followed by Soxhlet's extraction with acetone for 24 hours to
obtain 120 mg of powdery polymeric compound 11 of the present
invention. ##STR32##
[0149] This luminescence was also similar to photoluminescence of
the resultant polymeric compound 11 measured in its toluene
solution, so that it was confirmed that the luminescence was that
emitted from this luminescence material.
[0150] The characteristics of the organic luminescence device were
measured at room temperature by using a micro-current meter
("4140B", made by Hewlett-Packard Corp.) for a current-voltage
characteristic and "BM7" (made by Topcon K.K.) for an emission
luminance. The device using the polymeric compound 11 of this
example showed a good rectification characteristic. Further, when
the organic luminescence device was supplied with a voltage of 15 V
(volts) between upper and lower electrodes, luminescence from the
organic luminescence device was confirmed at a practical operation
temperature range (-20.degree. C. to 60.degree. C.). In this
Example 8, luminescence of (two) broad peaks (530 n and 550 nm)
resulting from the two species of Ir complexes which might be
attributable to the compound 4 and the compound 6 was
confirmed.
EXAMPLE 9
[0151] An organic luminescence device was prepared and evaluated in
the same manner as in Example 7 except that a mixture obtained by
mixing the polymeric compound 11 synthesized in Example 8 with PVK
(polyvinyl carbazole) in a weight ratio of 1:10.
[0152] The resultant luminescence device showed a good
rectification characteristic and, luminescence from the
luminescence device was confirmed when a voltage of 13 V (volts)
was applied to the device. Further, the luminescence was similar to
photoluminescence of the luminescent material used in this example
measured in a toluene solution, so that it was confirmed that the
luminescence was that emitted from the polymeric compound 11
(iridium complex).
EXAMPLE 10
[0153] Luminance half times were measured in the same manner as in
Example 4 except for using the luminescence devices of Example 7
and Example 9. The results are shown in Table 2 hereinafter.
COMPARATIVE EXAMPLE 2
[0154] An organic luminescence device was prepared and evaluated in
the same manner as in Example 7 except that a mixture prepared by
mixing the above-mentioned Ir(ppy).sub.3 in the following polymeric
compound 12 having no metal complex segment synthesized in the same
manner as in Example 1 in a weight ratio of 1:10, as the
luminescent material for the luminescence layer 12. The results are
shown in Table 2. ##STR33##
[0155] It has been found that the devices using the polymeric
compounds of the present invention clearly exhibited longer
luminance half times than the device using the conventional
luminescent material, thus allowing a device having a high
durability attributable to stability of the luminescent materials
of the present invention. TABLE-US-00003 TABLE 2 Luminescent
material Luminescent half time for luminescence layer (hours)
Device of Example 7 Polymeric compound 9 600 Device of Example 9
Mixture of polymeric 650 compound 11 with PVK (1:10) Device of
Comparative Mixture of Ir(ppy).sub.3 with 350 Example 2 polymeric
compound 12 (1:10)
EXAMPLE 11
[0156] Hereinbelow, two examples of display apparatus are
described. First, an example of preparation of a picture (image)
display apparatus having an XY (simple)-matrix wiring (structure)
is shown in FIG. 2.
[0157] On a glass substrate 21 measuring 150 mm-length (vertical),
150 mm-width (horizontal) and 1.1 mm-thickness, a ca. 100 nm-thick
ITO film was formed by sputtering and patterned into 100 lines of
100 .mu.m-wide transparent matrix electrodes (anode side) with a
spacing of 40 .mu.m as simple matrix electrodes 22. Then, a
three-layered organic compound layer 23 was formed thereon under
the same conditions as in Example 3.
[0158] Then, 100 lines of 100 .mu.m-wide metal electrodes 24 were
formed with a spacing of 40 .mu.m by mask vacuum deposition so as
to be perpendicular to the transparent electrodes by vacuum
deposition at a vacuum of 2.times.10.sup.-5 Torr. The metal
electrodes were formed of Al in a thickness of 150 nm after forming
a 5 nm-thick KF film as an undercoating layer. The thus-obtained
100.times.100-simple matrix-type organic EL device was subjected to
a simple matrix drive in a glove box filled with nitrogen at
voltages of 7 volts to 13 volts by using a scanning signal of 10
volts and data signals of .+-.3 volts as shown in FIG. 3. As a
result of an interlaced drive at a frame frequency of 30 Hz,
white/black binary pictures (images) were confirmed.
[0159] As a picture display apparatus, the high-efficiency
luminescence device of the present invention allows a light-weight
flat panel display with economized energy consumption and
high-recognizability. As a printer light source, the luminescence
devices of the present invention may be arranged in a line and
disposed in proximity to the photosensitive drum, to be utilized as
a line shutter wherein the respective devices are driven
independently from each other to effect desired exposure on the
photosensitive drum. On the other hand, the energy consumption
economization effect can be expected in application as an
illumination device or a backlight for a liquid crystal display
apparatus.
[0160] For another application to a picture display device, it is
particularly advantageous to form an active matrix-type picture
display device (panel) equipped with thin film transistors (TFTs)
instead of the above-mentioned XY-matrix wiring.
[0161] FIG. 4 is a schematic plan view of the above-mentioned
panel. Circumferentially outside the panel are disposed a drive
circuit comprising a scanning signal driver and a current supply
source, and a data signal driver as a display signal input means
(called a picture data supply means), which are respectively
connected to X-direction scanning lines called gate lines and
Y-direction lines called data lines, and current supply lines. The
scanning signal driver sequentially selects the gate scanning
lines, and in synchronism therewith, picture signals are supplied
from the data signal driver. Display pixel electrodes are disposed
at intersections of the gate scanning lines and the data lines.
[0162] The active device used in the present invention need not be
particularly restricted, and can also be a single-crystal silicon
TFT, an amorphous silicon (a-Si) TFT, etc.
[0163] On the above-mentioned pixel electrodes, multiple layers or
a single layer of organic luminescence layer may be formed and
metal electrodes as cathode are sequentially laminated to provide
an active-type organic luminescence display device.
INDUSTRIAL APPLICABILITY
[0164] As described above, according to the present invention, it
is possible to employ a novel main chain-type or side chain-type
polymeric compound showing a phosphorescent characteristic. By
using this polymeric compound in a luminescence layer, it is
possible to obtain an organic luminescence device less causing a
concentration extinction (deactivation) while having a high
luminescence efficiency. It is also effective in prolonging the
life of the device. Further, in combination with an active element
particularly using a thin film transistor (TFT), it becomes
possible to provide good halftones and stable display even in a
long-period display.
* * * * *