CN101300692A - Organic electroluminescent device - Google Patents

Organic electroluminescent device Download PDF

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CN101300692A
CN101300692A CNA2006800407577A CN200680040757A CN101300692A CN 101300692 A CN101300692 A CN 101300692A CN A2006800407577 A CNA2006800407577 A CN A2006800407577A CN 200680040757 A CN200680040757 A CN 200680040757A CN 101300692 A CN101300692 A CN 101300692A
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宫崎浩
平安山夏美
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Nippon Steel Chemical Co Ltd
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Disclosed is an organic electroluminescent device (organic EL device) utilizing phosphorescent emission, wherein the luminous efficiency is improved and driving stability is sufficiently secured. Specifically disclosed is an organic EL device wherein an anode (2), a hole transporting layer (4), an organic layer containing a light-emitting layer (5) and an electron transporting layer (6), and a cathode (7) are arranged in layers on a substrate (1). The hole transporting layer is arranged between the light-emitting layer and the anode, while the electron transporting layer is arranged between the light-emitting layer and the cathode. The light-emitting layer contains an organic Al complex represented by the general formula (I) below as a host material, and an organic Ir complex represented by the general formula (II) below as a guest material. In the formulae below, L represents ArO-, ArCOO-, Ar3SiO-, Ar3GeO- or Ar2AlO-.

Description

Organic electroluminescence device
Technical field
The present invention relates to organic electroluminescence device (hereinafter referred to as organic EL device), specifically, relate to by the luminescent layer that includes organic compounds being applied the film-type device that electric field is emitted light.
Technical background
In the exploitation of the electroluminescent device that has used organic material, by being the kind optimization that purpose makes electrode to improve from the electric charge injection efficiency of electrode, between electrode, be provided with the hole transmission layer that comprises aromatic diamine and comprise the exploitation of device of the luminescent layer of oxine aluminium complex (hereinafter referred to as Alq3) as film, compare with the existing device of the monocrystalline of anthracene etc. that used, luminous efficiency has obtained significantly improving, thereby turns to target with the practicality to the high-performance flat board of the feature with self-luminous high-speed responsive and obtained progress.
In order further to improve the efficient of such organic EL device, structure based on above-mentioned anode/hole transmission layer/luminescent layer/negative electrode, hole injection layer suitably is set therein, the device of electron injecting layer or electron transfer layer, for example anode/hole injection layer/hole transmission layer/luminescent layer/negative electrode, anode/hole injection layer/luminescent layer/electron transfer layer/negative electrode, anode/hole injection layer/luminescent layer/electron transfer layer/electron injecting layer/negative electrode, the isostructural device of anode/hole injection layer/hole transmission layer/luminescent layer/hole blocking layer/electron transfer layer/negative electrode is known.This hole transmission layer has and will be delivered to the function of luminescent layer from the hole injection layer injected holes, and electron transfer layer has and will be delivered to the function of luminescent layer from the negative electrode injected electrons.Should illustrate, also hole injection layer is called anode buffer layer sometimes, electron injecting layer is called cathode buffer layer.
In addition, known between luminescent layer and hole injection layer, inserting this hole transmission layer, can under lower electric field, inject a large amount of holes to luminescent layer, in addition because the electron pole difficulty flows through hole transmission layer, thereby just being accumulated in luminescent layer from the electronics that negative electrode or electron transfer layer inject luminescent layer, luminous efficiency rises.
Similarly, known between luminescent layer and electron injecting layer, inserting electron transfer layer, can under lower electric field, inject a large amount of electronics to luminescent layer, in addition since the hole extremely difficulty flow through electron transfer layer, thereby just being accumulated in luminescent layer from the hole that anode or hole transmission layer inject luminescent layer, luminous efficiency rises.According to the function of this structure sheaf, carried out the exploitation of multiple organic material so far.
On the other hand, with the device that is provided with the hole transmission layer that comprises aromatic diamine and comprises the luminescent layer of Alq3 is that most devices of representative all utilize fluorescence radiation, if and utilize phosphorescence luminous, if i.e. utilization is luminous from the generation of triplet excitation state, compare with the existing device of fluorescence (singlet state) that used, can expect that the efficient about 3 times improves.In order to realize this purpose, to studying as luminescent layer, but can only obtain extremely low briliancy with coumarin derivative or benzophenone derivates.Then, as the trial that utilizes triplet, study utilizing europium complex, but it does not reach high efficiency light-emitting yet.
In recent years, reported by using platinum complex (PtOEP), can rubescent expeditiously look phosphorescence.Afterwards, by doped iridium complex compound in luminescent layer (Ir (ppy) 3), made the high efficient green luminescent device that utilizes same phosphorescence luminous.
For this iridium complex, found to send the light of the wide wave-length coverage from the cyan to the redness by making the altered chemical structure of its part.But, for think the most stable and useful three ligand complexes as complex compound, clear and definite can only being prepared with limited part, as its avoidance method, proposed with the iridium chloride is parent material, experienced the heterocomplex (Proceeding of SPIE, the 4105th volume, the 119th page) of cross-linked structure intermediate.
Existing document related to the present invention is following document.
Patent documentation 1: the spy opens the 2002-299061 communique
Patent documentation 2: the spy opens the 2001-313178 communique
Patent documentation 3: the spy opens the 2002-352957 communique
Patent documentation 4: special table 2003-515897 communique
Non-patent literature 1:Appl.Phys.Lett., the 77th volume, the 904th page
In the exploitation of phosphorescence organic EL device,, 4,4 '-two (9-carbazyl) biphenyl (hereinafter referred to as CBP) of introducing in the patent documentation 2 are arranged as material of main part.If use the material of main part of CBP as three (2-phenylpyridine) iridium complex (hereinafter referred to as Ir (ppy) 3) of green phosphorescent luminescent material, then CBP easily makes the hole flow through and be difficult for making the characteristic that electronics flows through except having, also break electric charge and injected balance, make superfluous hole flow to the electric transmission side, the result descends the luminous efficiency from Ir (ppy) 3.
As above-mentioned solution, the method that hole blocking layer is set is arranged between luminescent layer and electron transfer layer.By utilizing this hole blocking layer that the hole is accumulated in the luminescent layer efficiently, can improve in luminescent layer the join probability again with electronics, realize high efficiency light-emitting.As present normally used hole barrier materials, can enumerate 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (hereinafter referred to as BCP) and to phenyl phenol generation-two (2-methyl-8-quinolinol generation-N1,08) aluminium (hereinafter referred to as BAlq).Can prevent to produce the combination again in electron transfer layer of electronics and hole like this, but BCP also crystallization easily at room temperature lack as reliability of material, so device lifetime is extremely short.In addition, reported better result's device lifetime of BAlq, but the hole barrier scarce capacity, from the luminous efficiency decline of Ir (ppy) 3.In addition, because layer structure increases by 1 layer, so device architecture complicates the problem that exists cost to increase.
In the patent documentation 3, the material of main part as the phosphorescence organic EL device has proposed 3,5-diphenyl-4-(1-naphthyl)-1,2,4-triazole (hereinafter referred to as TAZ), but except easily flowing through electronics and be difficult for flowing through the characteristic in hole, light-emitting zone deflection hole transmission layer side.Therefore, because because of the difference of hole transport layer material and the consistency problem of Ir (ppy) 3, from the luminous efficiency reduction of Ir (ppy) 3.For example, from high-performance, high reliability, high life aspect the most suitable as hole transmission layer use 4,4 '-two (N-(1-naphthyl)-N-phenyl amino) biphenyl is (poor with the compatibility of Ir (ppy) 3 hereinafter referred to as α-NPD), caused the energy transfer to α-NPD from TAZ, reduce to the efficient of the energy transfer of Ir (ppy) 3 from Ir (ppy) 3, the result exists the problem that luminous efficiency reduces.
As above-mentioned solution, have and use 4,4 '-two (N, N '-(3-toluyl) amino)-3,3 '-dimethyl diphenyl (hereinafter referred to as HMTPD) is such can not cause that energy is from the material of Ir (ppy) the 3 migrations method as hole transmission layer.In the non-patent literature 1, reported by in the material of main part of luminescent layer, using TAZ, 1, two (N, the N-tert-butyl group-phenyl)-1 of 3-, 3,4-oxazole or BCP use Ir (ppy) 3 in guest materials, use Alq3 in electron transfer layer, in hole transmission layer, use HMTPD, in the phosphorescence luminescent device, can obtain high efficiency light-emitting by 3-tier architecture, particularly used the system excellence of TAZ.But, because the glass transition temperature (Tg) of HMTPD is about 50 ℃, be easy to crystallization, lack as reliability of material.Therefore, device lifetime is extremely short, is difficult to carry out commerce and uses, and also has the high problem of driving voltage.
Patent documentation 1 discloses the organic EL device that comprises luminescent layer, the dopant that this luminescent layer has the main body agent and phosphoresces, as an example of this dopant, reported Ir (ppy) 3, replaced three ligand complexes that coordination on the part of benzothiazole structure has I r at phenyl.
Summary of the invention
For organic EL device being applied to the display device of flat-panel monitor etc., must be when improving the luminous efficiency of device, the stability when fully guaranteeing to drive.The purpose of this invention is to provide high efficiency, long-life and make the device architecture of simplification become organic EL device useful in the possible practicality.
The present invention relates to organic electroluminescence device, this organic electroluminescence device forms by stacked anode on substrate, the organic layer that comprises hole transmission layer, luminescent layer and electron transfer layer and negative electrode, between luminescent layer and anode, has hole transmission layer, between luminescent layer and negative electrode, has electron transfer layer, it is characterized in that: in luminescent layer, contain the metal-organic complex shown in the following general formula (I) as material of main part, and contain the metal-organic complex shown in the general formula (II) as guest materials.
Figure A20068004075700071
In the formula, R 1～R 6Represent hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, alkoxyl independently of one another, can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle.L represents 1 valency group shown in following general formula (1), (2), (3) or (4):
-O-Ar 1 (1)
Figure A20068004075700081
Ar 1～Ar 5Expression independently of one another can have substituent aromatic cyclic hydrocarbon group and maybe can have substituent aromatic heterocycle, and Z represents silicon or germanium, R 1～R 6Have and the identical implication of general formula (I).
Figure A20068004075700082
In the formula, R 7～R 14Represent hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, alkoxyl independently of one another, can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle.
The what is called that organic EL device of the present invention relates to the metal-organic complex (being also referred to as the Ir complex compound) that contains in the luminescent layer shown in (being also referred to as the Al complex compound) compound of the metal-organic complex shown in the above-mentioned general formula (I) and the above-mentioned general formula (II) has been utilized the organic EL device of phosphorescence.Use the Al complex compound shown in the general formula (I) as material of main part, and use the Ir complex compound shown in the general formula (II) as the phosphorescent guest materials.
Wherein, so-called material of main part is meant to account for the above composition of 50 weight % in the material that forms this layer that so-called guest materials is meant the composition that accounts for less than 50 weight % in the material that forms this layer.In the organic EL device of the present invention, the excited triplet state energy level that the Al complex compound that contains in the luminescent layer has the energy state higher than the excited triplet state energy level of the phosphorescent Ir complex compound that contains in this layer is being necessary basically.
In addition, hope is the film shape that can provide stable, has high Tg, the compound of high efficiency of transmission hole and/or electronics.In addition, also requiring is electrochemistry and chemically stable, during fabrication or be difficult to produce the compound that forms trap or eliminate luminous impurity when using.In order to make the luminous influence that is not vulnerable to the excited triplet state energy level of hole transmission layer of phosphorescent organic complex, therefore have and guarantee that it also is important that there is the hole injectability of appropriate distance light-emitting zone and hole transport bed boundary.
Form material as the luminescent layer that satisfies these conditions, use the Al complex compound shown in the above-mentioned general formula (I) among the present invention as material of main part.In the general formula (I), R 1～R 6Represent hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, alkoxyl independently of one another, can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle.As alkyl, preferred illustration carbon number is 1～6 alkyl (hereinafter referred to as low alkyl group), as aralkyl, preferred illustration benzyl, phenethyl, as alkenyl, preferred illustration carbon number is 1～6 low-grade alkenyl, as the alkyl portion of alkoxyl, preferred illustration low alkyl group.
In addition, as aromatic hydrocarbyl, aromatic hydrocarbyls such as preferred illustration phenyl, naphthyl, acenaphthenyl, anthryl, as aromatic heterocycle, aromatic heterocycles such as preferred illustration pyridine radicals, quinolyl, thienyl, carbazyl, indyl, furyl.When they when having substituent aromatic hydrocarbyl or aromatic heterocycle, as substituting group, can enumerate low alkyl group, lower alkoxy, phenoxy group, benzyloxy, phenyl, naphthyl etc.
Compound shown in the general formula (I) is more preferably selected R 1～R 6Compound for hydrogen atom, low alkyl group or lower alkoxy.
In the general formula (I), L represents the group shown in above-mentioned general formula (1), (2), (3) or (4), Ar 1～Ar 5Expression independently of one another can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle, and Z represents silicon or germanium.As preferred Ar 1～Ar 2, can enumerate the aromatic hydrocarbyl that phenyl, naphthyl or they are replaced by alkyl or aryl.As this alkyl, low alkyl groups such as preferable methyl, as aryl, the group that preferred phenyl, naphthyl or they are replaced by low alkyl group.As preferred Ar 3～Ar 5, can enumerate the phenyl that phenyl or low alkyl group replace.The R of above-mentioned general formula (4) 1～R 6Has R with the middle explanation of above-mentioned general formula (I) 1～R 6Identical implication.
Al complex compound shown in the general formula (I) carries out complex compound by the compound shown in for example corresponding slaine and the compound shown in the formula (III) and formula (1 '), (2 ') or (3 ') with 2 to 1 mol ratio and forms to react and synthesize.Should illustrate, in the formula (III), R 1～R 6R with general formula (I) 1～R 6Correspondence, in formula (1 ')～(3 '), Ar 1～Ar 5With the Ar of Z corresponding to the L in the general formula (I) 1～Ar 5And Z.
Figure A20068004075700101
HO-Ar 1
(1′)
Figure A20068004075700102
L is the Al complex compound shown in the general formula (I) of group shown in the general formula (4), and it is synthetic that slaine by correspondence and the complex compound between the compound shown in the formula (III) form reaction.Synthetic reaction is for example by being undertaken by the method shown in the Y.Kushi etc. (J.Amer.Chem.Soc., the 92nd volume, the 91st page, 1970).
Al complex compound shown in the following illustration general formula (I), but be not limited to following compound.Have again, abbreviate compound 1 as BmqAl, abbreviate compound 11 as BAlq.
Figure A20068004075700111
(compound 1)
Figure A20068004075700112
(compound 2)
Figure A20068004075700113
(compound 3)
(compound 4)
Figure A20068004075700115
(compound 5)
Figure A20068004075700121
(compound 11)
Figure A20068004075700122
(compound 12)
Figure A20068004075700123
(compound 13)
Figure A20068004075700124
(compound 14)
Figure A20068004075700125
(compound 15)
(compound 16)
Figure A20068004075700131
(compound 17)
Figure A20068004075700132
(compound 18)
Figure A20068004075700133
(compound 19)
Figure A20068004075700134
(compound 20)
Figure A20068004075700135
(compound 21)
Figure A20068004075700136
(compound 22)
As the guest materials in the luminescent layer, use the Ir complex compound shown in the above-mentioned general formula (II).
In the general formula (II), R 7～R 14Represent hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, alkoxyl independently of one another, can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle.In addition, the R of adjacency 7And R 8, R 8And R 9, R 9And R 10, R 11And R 12, R 12And R 13, R 13And R 14Can form ring, these rings can be aromatic rings.
As alkyl, preferred illustration carbon number is 1～6 alkyl (hereinafter referred to as low alkyl group), as aralkyl, preferred illustration benzyl, phenethyl, as alkenyl, preferred illustration carbon number is 1～6 low-grade alkenyl, as the alkyl portion of alkoxyl, preferred illustration low alkyl group.
In addition, as aromatic hydrocarbyl, preferred illustration phenyl, naphthyl, acenaphthenyl, anthryl etc., as aromatic heterocycle, preferred illustration pyridine radicals, quinolyl, thienyl, carbazyl, indyl, furyl etc.When they when having substituent aromatic hydrocarbyl or aromatic heterocycle, as substituting group, can enumerate low alkyl group, lower alkoxy, phenoxy group, benzyloxy, phenyl, naphthyl etc.
As preferred Ir complex compound, can enumerate Irbt3 etc.The concrete example of the metal-organic complex shown in the general formula (II) below is shown, but is not limited to following compound.Should illustrate, abbreviate compound 31 as Irbt3.
Figure A20068004075700151
(compound 31)
Figure A20068004075700152
(compound 32)
Figure A20068004075700153
(compound 33)
Figure A20068004075700154
(compound 34)
Figure A20068004075700155
(compound 35)
Figure A20068004075700156
(compound 36)
Figure A20068004075700157
(compound 37) (compound 38)
The material of main part that is used for luminescent layer among the present invention can make electronics and hole approximate equality ground flow through, and therefore can make it luminous in the central authorities of luminescent layer.Therefore, can not resemble the TAZ in of the migration of the luminous and produce power of hole transport side to hole transmission layer, cause efficient to reduce, can not resemble the CPB luminous in the electron transfer layer side yet, thereby make energy efficient be reduced, can use as the α-NPD of hole transmission layer with as the high material of the such reliability of the Alq3 of electron transfer layer to the electron transfer layer migration.
Description of drawings
Fig. 1 is the schematic cross-section of an example of expression organic electroluminescence device.
The explanation of Reference numeral
1: substrate, 2: anode, 3: hole injection layer, 4: hole transmission layer, 5: luminescent layer, 6: electron transfer layer, 7: negative electrode
Embodiment
Below, with reference to accompanying drawing organic EL device of the present invention is described.Fig. 1 is the sectional view of the structure example of the general organic EL device schematically representing to use among the present invention.In the organic EL device of the present invention, have substrate 1, anode 2, hole transmission layer 4, luminescent layer 5, electron transfer layer 6 and negative electrode 7 as essential layer, can omit the layer beyond essential layer, for example hole injection layer 3, in addition, other layers can be set in case of necessity.But in the organic EL device of the present invention, hole blocking layer is inessential.Owing to hole blocking layer is not set, make a layer structure obtain simplifying, bring the advantage in the manufacturing, on the performance.
Substrate 1 becomes the support of organic electroluminescence device, can use plate, metallic plate or metal forming, plastic film or the sheet etc. of quartz or glass.Special preferred glass plate, the plate of lucites such as polyester, polymethacrylates, Merlon, polysulfones.When using the synthetic resin substrate, essential attention barrier properties for gases.If the barrier properties for gases of substrate is too small, then cause the organic electroluminescence device deterioration, so not preferred owing to see through the extraneous gas of substrate.Therefore, also be one of preferable methods by fine and close silicon oxide layer etc. is set at least one face of synthetic resin substrate with the method for guaranteeing barrier properties for gases.
Substrate 1 is provided with anode 2, and anode has played the effect to the hole transmission layer injected hole.This anode is usually by metals such as aluminium, gold, silver, nickel, palladium, platinum, the metal oxides such as oxide of indium and/or tin, metal halides such as cupric iodide, carbon black, or formations such as electroconductive polymer such as poly-(3 methyl thiophene), polypyrrole, polyaniline.The formation of anode adopts sputtering method, vacuum vapour deposition etc. to carry out usually mostly.In addition, under the situation of the metal oxide microparticle of particulates such as metal particles such as silver, cupric iodide, carbon black, conductivity, electroconductive polymer micropowder etc., also can be coated on the substrate 1, form anode 2 by being scattered in the suitable adhesive resin solution.In addition, under the situation of electroconductive polymer, also can directly on substrate, form film, thereby perhaps form anode by coating electroconductive polymer on substrate by electrolysis polymerization.Anode also can be with the stacked formation of different materials.The thickness of anode is different because of the required transparency.When the needs when transparency, the transmitance that makes visible light usually is more than 60%, preferred more than 80%, and at this moment, thickness is generally 5～1000nm, about preferred 10～500nm.When can be when opaque, anode 2 can be identical with substrate 1.In addition, also further laminated different electric conducting material on above-mentioned anode.
Anode 2 is provided with hole transmission layer 4.Between also can be provided with hole injection layer 3.As the desired condition of the material of hole transmission layer, must be that hole injection efficiency from anode is high and can transmit the material of institute's injected holes efficiently.Therefore, require ionization potential little, high to the transparency of visible light, and hole mobility is big, and then excellent in stability, during fabrication or be difficult to produce the impurity that forms trap when using.In addition, owing to join, therefore require not eliminate the light that sends from luminescent layer with luminescent layer 5, thus perhaps and luminescent layer between do not form exciplex efficient reduced.Except above-mentioned general requirement, when considering the application of vehicle-mounted demonstration, also require to have thermal endurance for device.Therefore, the material of preferred Tg with the value more than 85 ℃.
In the organic EL device of the present invention,, can use the so known triarylamine dimer of α-NPD as hole mobile material.
Should illustrate, as required also can be with known compound as other hole mobile materials and triarylamine dimer and usefulness.Can enumerate the tertiary amine that for example contains more than 2 and the aromatic rings that condenses more than 2 is replaced in aromatic diamine, 4 on the nitrogen-atoms, 4 '; 4 "-three (1-naphthyl phenyl amino) triphenylamine etc. has the aromatic amines compound, 2 that the tetramer of aromatic amines compound, the triphenylamine of star structure is formed, 2 ', 7,7 '-four-(diphenyl amino)-9,9 '-spiro-compounds such as spiral shell two fluorenes etc.These compounds can use separately, also can mix use as required.
In addition, except above-claimed cpd,, can enumerate Polyvinyl carbazole, polyvinyl triphenylamine, contain the macromolecular materials such as poly (arylene ether) sulfone of tetraphenyl benzidine as the material of hole transmission layer.
Forming with rubbing method under the situation of hole transmission layer, the additives such as adhesive resin, coating improver that add hole mobile material more than a kind and can not form the trap in hole as required, by dissolving preparation coating solution, be coated on the anode 2 by methods such as method of spin coating, form hole transmission layer 4 by drying.As adhesive resin, can enumerate Merlon, polyarylate, polyester etc.If the addition of adhesive resin is many, hole mobility is reduced, therefore wish that its addition is few, be preferably usually below the 50 weight %.
Under situation about forming with vacuum vapour deposition, hole mobile material is put into the crucible that is arranged on vacuum tank, will be pumped to 10 in the vacuum tank with suitable vacuum pump -4About Pa, heating crucible then makes the hole mobile material evaporation, forms hole transmission layer 4 on the substrate that is formed with anode that is provided with in opposite directions with crucible.The thickness of hole transmission layer is generally 5～300nm, is preferably 10～100nm.In order to be formed uniformly so thin film, generally usually use vacuum vapour deposition.
Hole transmission layer 4 is provided with luminescent layer 5.Luminescent layer contains the Ir complex compound shown in Al complex compound shown in the general formula (I) and the general formula (II), providing between the electrode of electric field, by the hole injecting from anode and move through hole transmission layer be excited from negative electrode injection and the combining again of electronics that move through electron transfer layer 6, demonstrate luminous by force.Should illustrate that in the scope of not damaging performance of the present invention, luminescent layer 5 can contain other compositions such as other material of main parts (bringing into play the identical effect of complex compound with general formula (I)) or fluorchrome.
The content of Ir complex compound in luminescent layer shown in the general formula (II) is preferably in the scope of 0.1～30 weight %.When being 0.1 weight % when following, there is not help for the raising of the luminous efficiency of device, and when surpassing 30 weight %, form 2 aggressiveness etc. between the Ir complex compound and cause the concentration delustring, cause luminous efficiency to reduce.Used in the device of fluorescence (singlet state) existing, tended to preferred more slightly than the amount of the fluorescent coloring that contains in the luminescent layer (dopant).The Ir complex compound can partly be included in the luminescent layer with respect to film thickness direction, perhaps distributes unevenly.The thickness of luminescent layer 5 is generally 10～200nm, is preferably 20～100nm.Adopt the method formation film same with hole transmission layer.
In order further to improve the luminous efficiency of device, between luminescent layer 5 and negative electrode 7, electron transfer layer 6 is set.Electron transfer layer is by can forming from the compound of negative electrode injected electrons to the direction transmission of luminescent layer efficiently between the electrode that has applied electric field.As the electron-transporting compound that uses in the electron transfer layer 6, thereby must be that electron injection efficiency from negative electrode 7 is high and have a compound that high electron mobility can transmit institute's injected electrons efficiently.
As the electron transport material that satisfies such condition, can enumerate metal complex, metal complex, oxadiazole derivative, distyryl biphenyl derivative, silole derivative, 3-or the 5-flavonol metal complex of 10-hydroxy benzo [h] quinoline, benzoxazole metal complex, benzothiazole metal complex, three benzo imidazole radicals benzene, quinoxaline compounds, phenanthroline derivative, the 2-tert-butyl groups-9 such as Alq3,10-N, N '-dicyan anthraquinone diimine, the hydrogenated amorphous matter carborundum of n type, n type zinc sulphide, n type zinc selenide etc.The thickness of electron transfer layer 6 is generally 5～200nm, is preferably 10～100nm.Electron transfer layer is identical with hole transmission layer, forms by adopting rubbing method or vacuum vapour deposition to be laminated on the luminescent layer.Usually use vacuum vapour deposition.
For efficient that further improves the hole injection and the adhesive force that improves whole organic layer antianode, also can between hole transmission layer 4 and anode 2, insert hole injection layer 3.By inserting hole injection layer 3, has when initial device drive voltage reduces the effect that the voltage when suppressing with constant current Continuous Drive device rises.As the desired condition of the material that is used for hole injection layer, it is good to require with the adaptation of anode, can form uniform film, thermally-stabilised, i.e. fusing point and glass transition temperature height, and fusing point is more than 300 ℃, Tg is more than 100 ℃.It is low to enumerate ionization potential in addition, injects the hole from anode easily, and hole mobility is big.
For this purpose, phthalocyanine compounds such as copper phthalocyanine have been reported so far, organic compounds such as polyaniline, polythiophene, sputtering carbon, and metal oxide such as vanadium oxide, ruthenium-oxide, molybdenum oxide.For hole injection layer, also can form film, but under the situation of inorganic matter, can also use sputtering method or electron beam evaporation plating method, plasma CVD method by the mode identical with hole transmission layer.Thickness by the anode buffer layer 3 that forms with upper type is generally 3～100nm, is preferably 5～50nm.
Preferred electron transport layer 6 is layered on the luminescent layer 5, does not have hole blocking layer betwixt.
Negative electrode 7 plays the effect of injecting electronics in luminescent layer 5.As the material of negative electrode, can use the material that uses in the anode 2, inject in order to carry out electronics efficiently, the preferred low metal of work content can use proper metal or their alloys such as tin, magnesium, indium, calcium, aluminium, silver.As instantiation, can enumerate the alloy electrode of low work contents such as magnesium-silver alloy, magnesium-indium alloy, aluminum-copper-lithium alloys.The thickness of negative electrode is identical with anode usually.In order to protect the negative electrode that forms by low work function metal, high and to the metal level of atmospheric stability, the stability of increase device by further stacked work content on it.For this purpose, use metals such as aluminium, silver, copper, nickel, chromium, gold, platinum.
And then, between negative electrode 7 and electron transfer layer 6, insert LiF, MgF 2, Li 2O etc. as thin as a wafer dielectric film (0.1～5nm) as electron injecting layer, also is the effective ways that improve device efficiency.
Should illustrate, with Fig. 1 opposite configuration, promptly the sequential cascade according to negative electrode 7, electron transfer layer 6, luminescent layer 5, hole transmission layer 4, anode 2 also is fine on substrate 1, also can be as stating between at least one side is two plate bases of high transparent organic EL device of the present invention be set.In the case, also can append layer or omission layer as required.
Device, anode and the negative electrode that organic EL device of the present invention can be applicable to single device, be made up of the structure of array-like configuration is any of structure of the rectangular configuration of X-Y.According to organic EL device of the present invention, by luminescent layer being contained have the compound and the phosphorescent metal complex of specific skeleton, can obtain highlyer and drive the device that stability also is greatly improved, in the application of the flat board of panchromatic or polychrome, can bring into play excellent performance than adopted luminous device luminous efficiency from singlet state in the past
Embodiment
Below adopt synthesis example and embodiment that the present invention is described in more detail, as long as but be no more than its purport, the present invention is not limited to the record of following embodiment.
Embodiment 1
Hole injection layer uses copper phthalocyanine (CuPC), and hole transmission layer uses α-NPD, and electron transfer layer uses Alq3.On the glass substrate of the anode that the ITO that has formed by thickness 110nm forms, adopt vacuum vapour deposition, in vacuum degree 5.0 * 10 -4Stacked each film under the Pa.At first with
Figure A20068004075700201
Form the CuPC as hole injection layer/second on ITO, its thickness is 25nm.Secondly with
Figure A20068004075700202
The evaporation rate of/second forms the α-NPD as hole transmission layer on hole injection layer, its thickness is 55nm.
Secondly, be total to evaporation BmqAl (compound 1) and Irbt from different vapor deposition source at hole transmission layer 3(compound 31), forming thickness is the luminescent layer of 47.5nm.At this moment, Irbt 3Concentration be 7.0%.
Next, with
Figure A20068004075700203
The evaporation rate of/second forms the Alq3 as electron transfer layer, and its thickness is 30nm.Again with
Figure A20068004075700204
The evaporation rate of/second forms the lithia (Li as electron injecting layer on electron transfer layer 2O), its thickness is 1nm.At last, with
Figure A20068004075700205
The evaporation rate of/second forms the aluminium (Al) as electrode on electron injecting layer, its thickness is 100nm, thereby makes organic EL device.
Embodiment 2
Except being total to evaporation BAlq (compound 11) and Irbt from different vapor deposition source 3(compound 31), forming thickness is outside the luminescent layer of 47.5nm, makes organic EL device similarly to Example 1.Irbt should be described 3Concentration be 7.0%.
Comparative example 1
Except using bt 2Beyond the guest materials of Ir (acac) as luminescent layer, make organic EL device similarly to Example 1.Bt should be described 2Ir (acac) has Irbt 3A bt be replaced into the structure of acac (acetylacetonate).
Comparative example 2
Except using bt 2Beyond the guest materials of Ir (acac) as luminescent layer, make organic EL device similarly to Example 2.
Comparative example 3
Except using the material of main part of BCP, make organic EL device similarly to Example 1 as luminescent layer.
Comparative example 4
Except using the material of main part of BCP, use bt as luminescent layer 2Ir (acac) makes organic EL device similarly to Example 1 as beyond the guest materials.
With peak luminous wavelength, high-luminous-efficiency, the briliancy of each organic EL device of obtaining in embodiment and the comparative example (the initial stage briliancy 500cd/m that partly declines the life-span 2) be shown in table 1.
[table 1]
Peak luminous wavelength (nm) High-luminous-efficiency (cd/A) Briliancy partly decline the time (hr)
Embodiment 1 554 11.0 1000
Embodiment 2 554 11.4 1000
Comparative example 1 554 10.5 800
Comparative example 2 554 10.5 800
Comparative example 3 555 9.2 300
Comparative example 4 554 8.5 200
According to the present invention, can access and keep under the situation of good luminescent characteristic, have the organic EL device of making a long driver to move the life-span.Therefore, organic EL device of the present invention can be applied to light source (for example back light of photocopier light source, LCD and meters), display panel, sign lamp that flat-panel monitor (for example OA computer with or wall hung TV), Vehicular display device spare, mobile phone show and utilized the feature of planar luminous body, its technological value is big.

Claims (4)

1. organic electroluminescence device, this organic electroluminescence device is by stacked anode on substrate, comprise hole transmission layer, the organic layer of luminescent layer and electron transfer layer and negative electrode and form, between luminescent layer and anode, has hole transmission layer, between luminescent layer and negative electrode, has electron transfer layer, it is characterized in that: in luminescent layer, contain the metal-organic complex shown in the following general formula (I) as material of main part, and contain the metal-organic complex shown in the general formula (II) as guest materials
Figure A20068004075700021
In the formula, R 1～R 6Represent hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, alkoxyl independently of one another, can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle, L represents 1 valency group shown in following general formula (1), (2), (3) or (4)
-O-Ar 1 (1)
Figure A20068004075700022
Ar 1～Ar 5Expression independently of one another can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle, and Z represents silicon or germanium, R 1～R 6Have and the identical implication of general formula (I),
Figure A20068004075700031
In the formula, R 7～R 14Represent hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, alkoxyl independently of one another, can have substituent aromatic hydrocarbyl and maybe can have substituent aromatic heterocycle.
2. organic electroluminescence device as claimed in claim 1 wherein disposes hole injection layer at anode and hole transport interlayer.
3. organic electroluminescence device as claimed in claim 1 wherein disposes electron injecting layer at negative electrode and electric transmission interlayer.
4. organic electroluminescence device as claimed in claim 2 wherein disposes electron injecting layer at negative electrode and electric transmission interlayer.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102244204A (en) * 2011-07-04 2011-11-16 陕西科技大学 OLED device and preparation method thereof
CN103779498A (en) * 2014-01-23 2014-05-07 上海交通大学 Electron injection method of conductive polymeric materials

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JP4683829B2 (en) * 2003-10-17 2011-05-18 淳二 城戸 Organic electroluminescent device and manufacturing method thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102244204A (en) * 2011-07-04 2011-11-16 陕西科技大学 OLED device and preparation method thereof
CN102244204B (en) * 2011-07-04 2013-04-10 陕西科技大学 OLED device and preparation method thereof
CN103779498A (en) * 2014-01-23 2014-05-07 上海交通大学 Electron injection method of conductive polymeric materials

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