CN1934907A - Organic electroluminescent element - Google Patents
Organic electroluminescent element Download PDFInfo
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- CN1934907A CN1934907A CN 200580008340 CN200580008340A CN1934907A CN 1934907 A CN1934907 A CN 1934907A CN 200580008340 CN200580008340 CN 200580008340 CN 200580008340 A CN200580008340 A CN 200580008340A CN 1934907 A CN1934907 A CN 1934907A
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Abstract
Disclosed is an organic electroluminescent device (organic EL device) which has a simple structure and utilizes phosphorescence. The organic electroluminescent device is improved in luminous efficiency and secured of sufficient driving stability. Such an organic electroluminescent device comprises a light-emitting layer or a plurality of organic compound thin film layers including a light-emitting layer formed between a pair of electrodes. The light-emitting layer contains a compound composed of an Al complex of an oxyphenylbenzoxazole which is represented by the general formula (I) below as a host material, while containing an organic metal complex including Ru, Rh, Pd, Ag, Re, Os, Ir, Pt or Au as a guest material. (I) (In the formula, R1-R8 independently represent a hydrogen atom, an alkyl group, an aromatic group or the like; n represents 2 or 4; and Z represents an aromatic group, a triarylsilyl group or the like when n is 2, while representing Al(III) when n is 4).
Description
Technical field
The present invention relates to organic electroluminescent device (hereinafter referred to as organic EL), more particularly, relate to by the luminescent layer that is formed by organic compound is applied the film-type device that electric field is emitted light.
Background technology
In the exploitation of the electroluminescent cell that has used organic material, by being the type of electrodes optimization of purpose to improve from the efficient of electrode iunjected charge, exploitation is provided with the hole transmission layer that is made of aromatic diamine with form of film and the element of the luminescent layer that is made of oxine aluminium complex (hereinafter referred to as Alq3) between electrode, compare with the element that used monocrystal such as anthracene in the past, improved luminous efficiency significantly, thereby promoted practicalization to high-performance flat board with self-luminous high-speed responsive feature.
In order further to improve the efficient of such organic EL, structure based on above-mentioned anode/hole transmission layer/luminescent layer/negative electrode, hole injection layer suitably is set therein, electron injecting layer, the element of 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 element 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 transmission layer is called anode buffer layer sometimes.
In addition, known between luminescent layer and hole injection layer, inserting described hole transmission layer, can under lower electric field, inject a large amount of holes to luminescent layer, and because the electron pole difficulty flows through hole transmission layer, thereby injected electrons just is accumulated on the interface of hole transmission layer and luminescent layer from negative electrode or electric transmission course luminescent layer, thereby improved luminous efficiency.
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, and since the hole extremely difficulty flow through electron transfer layer, thereby injected holes just is accumulated on the interface of electron transfer layer and luminescent layer from anode or hole transport course luminescent layer, thereby improved luminous efficiency.According to the function of this structure sheaf, carried out the exploitation of multiple organic material so far.
On the other hand, with the element of the above-mentioned luminescent layer that is provided with the hole transmission layer that is made of aromatic diamine and is made of Alq3 is that many elements of representative adopt fluorescence radiations, but people wait in expectation and adopt phosphorescence luminous, if promptly be used to luminous from triplet excitation state, make efficient use the element of fluorescence (singlet) to improve about 3 times more in the past.In order to reach this purpose, studied with coumarin derivative, benzophenone derivates as luminescent layer, but only obtained extremely low brightness.Afterwards, as the trial that utilizes triplet state, study using europium complex, but reach high efficiency light-emitting not yet.
Reported recently by using platinum complex (T-1, PtOEP), expeditiously burn red (Nature, 395 volumes, the 151st page, 1998).Afterwards, by doped iridium complex compound in luminescent layer (T-2, Ir (ppy) 3), improved the efficient (Appl.Phys.Lett., 75 volumes, the 4th page, 1999) of glow green greatly.And report, these iridium complexs even component structure is more simplified, also can demonstrate high luminous efficiency (Appl.Phys.Lett., 77 volumes, the 904th page, 2000) by to the luminescent layer optimization.
Should illustrate that the chemical formula of above-mentioned T-1 and T-2 etc. is recorded in the following document, with it as a reference.In addition, the structural formula of normally used compound, abbreviation are also recorded in the following patent documentation in the organic layers such as material of main part, guest materials, hole injection layer, electron transfer layer, with it as a reference.Below do not indicate in the explanation and the abbreviation used is general in the art abbreviation, can understand by the meaning of abbreviation described in the following document etc.
Patent documentation 1: the spy opens the 2002-305083 communique
Patent documentation 2: the spy opens the 2001-313178 communique
Patent documentation 3: the spy opens the 2002-352957 communique
Patent documentation 4: the spy opens the 2000-200684 communique
Patent documentation 5: special table 2003-515897 communique
Patent documentation 6: the spy opens flat 10-25472 communique
Non-patent literature 1:Appl.Phys.Lett., 77 volumes, the 904th page, 2000
In the exploitation of phosphorescent organic electroluminescent element, the material of main part that is proposed is that the spy opens the carbazole compound CBP that introduces in the 2001-313178 communique.If use the material of main part of CBP as green phosphorescent luminescent material three (2-phenylpyridine) iridium complex (hereinafter referred to as Ir (ppy) 3), then CBP easily makes the hole flow through and be difficult for making the characteristic that electronics flows through except having, also broken the balance that electric charge injects, make superfluous hole flow to the electric transmission side, the result descends the luminous efficiency from Ir (ppy) 3.
The means that address the above problem have the method that hole blocking layer is set between luminescent layer and electron transfer layer.This hole blocking layer can make the hole be accumulated in the luminescent layer efficiently, thereby improves the probability that it combines with electronics in luminescent layer again, has realized 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) reaches 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 lack reliability, so component life is extremely short as the material of easy crystallization under the room temperature.In addition, the Tg that has reported BAlq is about 100 ℃ and better component life result, 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 component structure complicates the problem that exists cost to increase.
In addition, as spendable material of main part outside the CBP, the spy opens the 2002-305083 communique and discloses and use by group with nitrogen heterocyclic ring AR1 and aromatic rings Ar2 and complex compound (Ar that metal M is formed
1-Ar
2-O-)
nM uses the organic EL of the metal complex of precious metal as guest materials as the material of main part of luminescent layer.Illustrative herein material of main part has a lot, Ar
1Be benzoxazol ring, Ar
2For the compound of phenyl ring is one of illustrative numerous compounds.Wherein also illustration M be that Zn, n are 2 compound, but not much else.In addition, as guest materials, also enumerated the metal complex of a plurality of precious metal.Just have the use of 4 layers of structural detail of hole blocking layer but rested on illustration, be not able to address the above problem.
On the other hand, material of main part as the phosphorescent organic electroluminescent element, special 3-phenyl-4-(1 '-naphthyl)-5-phenyl-1 introduced in the 2002-352957 communique of opening has also been proposed, 2,4-triazole (hereinafter referred to as TAZ), but except easily flowing through electronics and being difficult for flowing through the characteristic in hole, light-emitting zone is in the hole transmission layer side.Therefore as can be known, because the affinity problem of hole transport layer material and 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 (hereinafter referred to as NPB) is poor with the affinity of Ir (ppy) 3, caused the energy transfer to NPB, existed the problem that luminous efficiency reduces from Ir (ppy) 3.
The means that address the above problem have uses 4,4 '-two (N, N '-(3-tolyl) amino)-3,3 '-dimethyl diphenyl (hereinafter referred to as HMTPD) and so on can not cause that energy is from the material of Ir (ppy) the 3 migrations method as hole transmission layer.
At Appl.Phys.Lett., 77 volumes, the 904th page, in 2000, reported by in the material of main part of luminescent layer, using TAZ, 1, the two (N of 3-, the N-tert-butyl group-phenyl)-1,3,4- azoles (hereinafter referred to as OXD7) or BCP, in dopant material, use Ir (ppy) 3, in electron transfer layer, use Alq3, in hole transmission layer, use HMTPD, in the phosphorescence light-emitting component, can obtain high efficiency light-emitting by 3-tier architecture, and use the system of TAZ to obtain excellent especially effect.But, because the Tg of HMTPD is about about 50 ℃, be the material that is easy to crystallization, lack reliability.Therefore, the life-span of element is extremely short, is difficult to carry out commerce and uses, and also has the high problem of driving voltage.
In addition, the spy opens to disclose in the 2000-200684 communique and comprises the organic EL that 2-(2-hydroxyphenyl) benzoxazoles 2 molecules and phenols 1 molecule are attached to the luminescent material of 1 complex compound on the Al.The compound of wherein enumerating is numerous, has also enumerated combination with dopant material as material of main part, has utilized fluorescence radiation but only rest on.
In addition, the spy opens the organic EL that discloses the luminescent material that the complex compound by 4 molecule hydroxyphenyl benzoxazols and Al-O-Al combination constitutes in the flat 10-25472 communique.The luminescent material of wherein enumerating is numerous, wherein to mixing illustration is arranged also, but not much else.
Summary of the invention
For organic EL being applied to the display element of flat-panel monitor etc., must be when improving the element luminous efficiency, the stability when fully guaranteeing to drive.In view of above-mentioned present situation, the purpose of this invention is to provide have high efficiency, the component structure of long-life and simplification and can carry out practical organic EL.
The present invention relates to organic electroluminescent device, described organic electroluminescent device is formed with the organic compound thin film layer that comprises luminescent layer between pair of electrodes, between luminescent layer and anode, has hole transmission layer, between luminescent layer and negative electrode, has electron transfer layer, between electron transfer layer and luminescent layer, do not have hole blocking layer, it is characterized in that, luminescent layer contains: as the compound shown in the following general formula (I) of material of main part, and be selected from ruthenium as containing of guest materials, rhodium, palladium, silver, rhenium, osmium, iridium, the metal-organic complex of at least a metal in platinum and the gold.
In the formula, Z represents to have substituent alkyl, group shown in aromatic heterocycle, diarye silyl or the following formula (II).
R
1～R
8And R
9～R
16Represent that independently of one another hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, amino, amide groups, alkoxy carbonyl group, carboxyl, alkoxyl maybe can have substituent aromatic group.
Wherein, when Z was group shown in the formula (II), general formula (I) was by shown in the following general formula (III).
In the formula, R
1～R
16Has implication same as described above.
As guest materials, preferably enumerate green phosphorescent luminiferous three (2-phenylpyridine) iridium complex.
Below the present invention is described in more detail.
Organic EL of the present invention relates to the organic EL that what is called has been utilized phosphorescence, and it contains in luminescent layer: the compound shown in the above-mentioned general formula (I) and contain the phosphorescent metal-organic complex that is selected from least a metal in periodic table 7～11 families.Has following luminescent layer: contain the compound shown in the general formula (I) as principal component, be selected from the metal-organic complex of at least a metal in ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and the gold as containing of accessory ingredient.
Wherein, principal component is meant the composition that accounts for more than or equal to 50 weight % in the material that forms this layer, and accessory ingredient is meant the composition of less than 50 weight % in the material that forms this layer.In organic electroluminescent device of the present invention, basic demand to compound shown in the general formula contained in the luminescent layer (I) is, have than phosphorescent metal-organic complex contained in this layer excite the triplet state energy levels higher excite the triplet state energy level.In addition, also must be to give stable film shape, and/or have high glass-transition temperature (Tg), the compound of transporting holes and/or electronics efficiently.And require in electrochemistry and chemically stable, when making or use, be difficult to produce the compound that forms trap or cause the impurity of delustring.
In addition, in order to make the luminous influence that excites the triplet state energy level that is not vulnerable to hole transmission layer of phosphorescent organic complex, another material particular is to possess the hole injectability that can make light-emitting zone and hole transport bed boundary keep the distance of appropriateness.
Form material as the luminescent layer that satisfies these conditions, use the compound shown in the above-mentioned general formula (I) among the present invention as material of main part.In general formula (I), R
1～R
8Represent hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, amino, amide groups, alkoxy carbonyl group, carboxyl, alkoxyl independently of one another, can have substituent aromatic group.As alkyl, preferred illustration carbon number is 1～6 alkyl (hereinafter referred to as low alkyl group), as aralkyl, and preferred illustration benzyl, phenethyl, as alkenyl, preferred illustration carbon number is 1～6 low-grade alkenyl, as amino, preferred illustration-NR
2Amino shown in (R is hydrogen or low alkyl group), as amide groups, preferred illustration-CONH
2, as the alkoxyl of alkoxy carbonyl group and alkoxyl, preferred illustration carbon number is 1～6 lower alkoxy.More preferably R
1～R
8All being hydrogen atom, perhaps is hydrogen atom more than 5, and other are the alkyl of carbon number below 3.
Can have substituent aromatic group, comprise to have substituent aromatic hydrocarbyl or aromatic heterocycle.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 its when having substituent aromatic hydrocarbyl or aromatic heterocycle, as substituting group, can enumerate low alkyl group, lower alkoxy, aryloxy group such as phenoxy group, toloxyl, arylthios such as thiophenyl, aralkoxies such as benzyloxy, aryl such as phenyl, naphthyl, xenyl, dimethylamino, heteroaryl etc.
As Z, can enumerate Phenoxyphenyl, the thiophenyl phenyl, diarye silyl is the triphenyl silicyl for example, aryl is phenyl, xenyl or naphthyl, naphthyl phenyl etc. for example, and heterocyclic radical is the group shown in pyrimidine radicals, pyridine radicals, thienyl, furyl, di azoly, benzoxazol base, bithiophene base and the formula (II) for example.Preferred Phenoxyphenyl, diarye silyl, aryl or heterocyclic radical.More preferably Phenoxyphenyl, triphenyl silicyl, phenyl, xenyl, naphthyl or naphthyl phenyl.Further preferred triphenyl silicyl, phenyl, xenyl or naphthyl phenyl.These groups can have substituting group, low alkyl groups such as methyl, ethyl, propyl group or butyl for example, halogen atoms such as fluorine atom, chlorine atom or bromine atoms, alkoxyls such as methoxyl group, ethyoxyl or propoxyl group, fluoro-alkyl is trifluoromethyl etc. for example, heterocyclic radical for example can have substituent di azoly, or nitro etc.Preferred substituted is that fluorine atom, methyl, the tert-butyl group, fluoro methyl, methoxyl group maybe can have substituent di azoly.More preferred substituents is methyl or trifluoromethyl.In addition, also preferred Z is the group shown in the formula (II).When Z was group shown in the formula (II), general formula (I) was represented by general formula (III).Wherein, R
9～R
16Preferably enumerate and R
1～R
8The identical group of middle explanation.
Compound shown in general formula (I) or the general formula (III) more preferably is selected from R
1～R
8And R
9～R
16Compound for hydrogen atom, low alkyl group or lower alkoxy.Further be preferably selected from R
1～R
8And R
9～R
16Whole or be hydrogen atom more than 10, other are the compound of low alkyl group or lower alkoxy.
The preferred concrete example of compound shown in general formula (I) or the general formula (III) below is shown, but is not limited to these.
Al complex shown in the general formula that uses among the present invention (I) can adopt known method easily to make.For example, at first form the complex shown in the general formula (a),, thereby make the complex shown in the general formula (I) then with the compound reaction shown in the general formula (b) by as follows.
Z-OH (b)
(in the formula, R
1～R
8R with Z and formula (I)
1～R
8With the Z correspondence, but do not comprise that Z is the situation of group shown in the formula (II).Y represents alkoxyl, halogen atom, hydroxyl or ionic group).
Al complex shown in the general formula (III) can adopt known method easily to make.Complex compound between the compound shown in the slaine of for example, employing correspondence and the following general formula (c) forms reaction and synthesizes.Synthetic reaction for example adopts the method shown in the Y.Kushi etc. (J.Amer.Chem.Soc., 92 volumes, 91 pages, 1970) to carry out.Should illustrate, in the formula (c), R
1～R
8R with general formula (I)
1～R
8Corresponding.
As the guest materials in the luminescent layer, contain the metal-organic complex that comprises at least a kind of metal that is selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold.This metal-organic complex is known in above-mentioned patent documentation etc., can select and uses it.
As preferred metal-organic complex, can enumerate with precious metal elements such as Ir as complex compound classes (formula C) such as complex compound class (formula B), PtOEt3 such as Ir (ppy) 3 classes such as complex compound such as grade (formula A) of central metal, Ir (bt) 2acac3.The instantiation of these complex compound classes is as follows, but is not limited to following compound.
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 that produce power reduces efficient to the migration of hole transmission layer in that the hole transport side is luminous the TAZ, can not resemble the CPB in the electron transfer layer side luminously and make energy efficient be reduced yet, can use as the NPB of hole transmission layer with as the so high material of the reliability with a large amount of production actual achievements of the Alq3 of electron transfer layer to the electron transfer layer migration.
Below, with reference to accompanying drawing organic EL of the present invention is described.Fig. 1 is the sectional view of the structure example of the general organic EL schematically representing to use among the present invention, 1 expression substrate, 2 expression anodes, 3 expression hole injection layers, 4 expression hole transmission layers, 5 expression luminescent layers, 6 expression electron transfer layers, 7 expression negative electrodes.In organic EL of the present invention, have substrate, anode, hole transmission layer, luminescent layer, electron transfer layer and negative electrode as necessary layer, can omit necessary layer layer in addition, for example hole injection layer in addition, can be provided with other layers in case of necessity.Organic EL of the present invention makes a layer structure obtain simplifying owing to hole blocking layer is not set, and brings advantage on making and on the performance.
In organic EL of the present invention, hole mobile material can use the known like this triarylamine dimer of above-mentioned NPB.
Can also use other known compound in case of necessity with the triarylamine dimer as hole mobile material.For example, can enumerate and contain more than or equal to 2 tertiary amine and more than or equal to 2 the aromatic diamine, 4 that aromatic rings is replaced in nitrogen-atoms that condenses, 4 ', 4 " three (1-naphthyl phenyl amino) triphenylamine etc. aromatic amines compound, 2 of having the aromatic amines compound of T_Starburst structure, forming by the tetramer of triphenylamine; 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 respectively in case of necessity.
In addition, except that above-claimed cpd,, can enumerate Polyvinyl carbazole, polyvinyl triphenylamine, contain the macromolecular materials such as polyether sulphone of tetraphenyl benzidine as the material of hole transmission layer.
When forming hole transmission layer with rubbing method, add and dissolve the hole mobile material more than a kind or 2 kinds and the resin glue of the trap that does not become the hole that uses in case of necessity and be coated with additive such as improver, be mixed with coating solution, coat on the anode 2 with methods such as spin-coating methods, dry back forms hole transmission layer 4.As resin glue, can enumerate Merlon, polyarylate, polyester etc.When the resin glue addition is big, hole mobility is diminished, therefore preferably add on a small quantity, usually preferably smaller or equal to 50 weight %.
When adopting vacuum vapour deposition to form, hole mobile material is put into the crucible that is arranged at vacuum tank, with suitable vacuum pump to carrying out exhaust in the vacuum tank until 10
-4About Pa, heating crucible makes the hole mobile material evaporation then, thereby is forming hole transmission layer 4 in opposite directions on the substrate that is formed with anode of crucible setting.The thickness of hole transmission layer 4 is generally 5～300nm, is preferably 10～100nm.In order to be formed uniformly so thin film, the preferred usually vacuum vapour deposition of using.
The content of above-mentioned metal-organic complex in luminescent layer is preferably the scope of 0.1～30 weight %.If less than 0.1 weight %, the luminous efficiency of element is improved, if surpass 30 weight %, then form dimer etc. between metal-organic complex and cause the concentration delustring, cause luminous efficiency to reduce.Compare with the amount of fluorescent coloring (dopant) contained in the luminescent layer in the element that adopted fluorescence (singlet) in the past, it is more slightly to tend to preferred this content.Metal-organic complex can be distributed on the film thickness direction in the luminescent layer locally, or distributes unevenly.
The thickness of luminescent layer 5 is generally 10～200nm, is preferably 20～100nm.Form film by the method identical with hole transmission layer 4.
In order further to improve the luminous efficiency of element, can between luminescent layer 5 and negative electrode 7, electron transfer layer 6 be set.Preferably between luminescent layer 5 and electron transfer layer 6, hole blocking layer is not set, the setting of joining between luminescent layer 5 and hole transmission layer 4 and electron transfer layer 6 are two-layer.Electron transfer layer 6 is by can efficiently the compound of carrying to the direction of luminescent layer 5 from the negative electrode injected electrons being formed between the electrode that has applied electric field.Electron-transporting compound as using in the electron transfer layer 6 must be the electron injection efficiency height from negative electrode 7, and have high electron mobility, can carry efficiently inject the compound of electronics.
As the electron transport material that satisfies this condition, can enumerate metal complex, metal complex, oxadiazole derivative, distyryl biphenyl derivative, シ ロ one Le derivative, 3-or the 5-flavonol metal complex of 10-hydroxy benzo [h] quinoline, benzoxazol 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, n shape hydrogenated amorphous carbon silicon, n type zinc sulphide, n type zinc selenide etc.The thickness of electron transfer layer 6 is generally 5～200nm, is preferably 10～100nm.
Identical with hole transmission layer 4, adopt rubbing method or vacuum vapour deposition by on luminescent layer 5, carrying out the laminated electron transfer layer 6 that forms.Usually adopt 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, can be when reducing element initial driving voltage, the effect that the voltage when having inhibition with constant current Continuous Drive element rises.As the required condition that possesses of the material that is used for hole injection layer, require itself and the contacting of anode, can form uniform film, thermally-stabilised, be fusing point and glass transition temperature height, fusing point is more than or equal to 300 ℃, and glass transition temperature is more than or equal to 100 ℃.It is low to enumerate ionization potential in addition, injects the hole from anode easily, the hole mobility height.
As the material that is used 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 when using 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.
The thickness of negative electrode 7 is identical with anode 2 usually.In order to protect the negative electrode that constitutes by low workfunction metal, can laminated further thereon work function height, to the metal level of atmospheric stability, thus increase the stability of element.For reaching this purpose, can use metals such as aluminium, silver, copper, nickel, chromium, gold, platinum.
In addition, between negative electrode and electron transfer layer, insert LiF, MgF
2, Li
2O etc. as thin as a wafer dielectric film (0.1～5nm) also is the effective ways that efficiency of element is improved as electron injecting layer.
Also have, also can take with Fig. 1 opposite configuration, promptly on substrate 1, carry out by the order of negative electrode 7, electron transfer layer 6, luminescent layer 5, hole transmission layer 4, anode 2 laminated, also can be by the mode of both stating at least one for organic EL of the present invention being set between two plate bases of high transparent.In the case, also can append layer or omission layer as required.
In the present invention, the structure that organic EL is applicable to single element fully, element, anode and the negative electrode be made up of the structure of array-like configuration are the rectangular configuration of X-Y.According to organic EL of the present invention, by luminescent layer being contained have the compound and the phosphorescent metal complex of specific skeleton, can obtain than adopted in the past luminous element luminous efficiency from singlet higher, drive the element that stability also is greatly improved, in the application of the screen of panchromatic or polychrome, can bring into play excellent performance.
Description of drawings
Fig. 1 is the sectional view of display organic electroluminescence light emitting element one example.
Embodiment
Below the present invention will be described in more detail by synthesis example and embodiment, but only otherwise exceed purport of the present invention, the present invention is not limited to the record content of following examples.
Synthesis example 1
In the 500ml there-necked flask that has carried out degassing nitrogen replacement, add aluminium isopropoxide 5.0g, 2-(2-hydroxyphenyl) benzoxazol 10.3g, add dry toluene 100ml to it and make its dissolving.Be heated to 60 ℃ then, stirred 30 minutes.Splash into the dry toluene 100ml that is dissolved with p-phenyl phenol 4.2g lentamente to it, stirred 4 hours down at 60 ℃ like this.Behind the cool to room temperature, the white precipitate that leaching generates washs with the order of toluene, ethanol.With its drying under reduced pressure, obtain white powder 6.6g.This compound is equivalent to the compound of the compound sequence number 12 shown in the illustrative general formula in front (I), therefore is called compound 12.Partly these compound 12 sublimation purifyings are used to make element.
Synthesis example 2
In the 100ml there-necked flask, add aluminium isopropoxide 9.8g, 2-(2-hydroxyphenyl) benzoxazol 20.3g, add 2-propyl alcohol 480ml, refluxed 4 hours to it.Add pure water 0.9ml then, refluxed again 2 hours.Behind the cool to room temperature, the white precipitate that leaching generates washs with the 2-propyl alcohol.With its drying under reduced pressure, obtain white powder 23.5g.The compound that obtains is a compound 33.Partly these compound 33 sublimation purifyings are used to make element.
Reference example 1
Adopting vacuum vapour deposition on glass substrate, is 4.0 * 10 with vacuum degree
-4Pa carries out evaporation, makes the thickness of compound 12, compound 33, TAZ or Alq3 formation 100nm with the evaporation rate of 1.0 /s.It is placed in atmosphere, under the room temperature, thin film stability is studied by measuring crystallization time.The results are shown in table 1.
Table 1
| Reach the fate of crystallization | |
| TAZ | Below 2～3 days |
| Compound 12 | More than 30 days |
| Compound 33 | More than 30 days |
| Alq3 | More than 30 days |
Reference example 2
Whether evaporation luminescent layer only on glass substrate is to being suitable for studying as the material of main part of Ir (ppy) 3.
Adopting vacuum vapour deposition on glass substrate, is 4.0 * 10 in vacuum degree
-4From different vapor deposition source evaporation compounds 12 or 33 and Ir (ppy) 3, forming thickness with 1.0 /s is that Ir (ppy) 3 concentration of 50nm are 7.0% film under the condition of Pa.In addition, by same mode, change the film principal component into TAZ and Alq3 and two (2-methyl-oxine phenol generation) aluminium (III)-mu-oxo-two (2-methyl-oxine phenol generation) aluminium (III) (hereinafter referred to as (Almq2) 20) and make film.
Estimate made film with fluorescence determination device.Excitation wavelength is compound 12, compound 33, TAZ, BAlq, Alq3 or (Almq2) 20 maximum absorption wavelength, observes the light that sends this moment.The results are shown in table 2.
Table 2
| Luminous from material of main part | Luminous from guest materials | |
| TAZ | × | ○ |
| Compound 12 | × | ○ |
| Compound 33 | × | ○ |
| BAlq | × | × |
| Alq3 | ○ | × |
| (Almq2)20 | × | × |
When using TAZ, compound 12 or 33 as the material of main part of luminescent layer, energy produces phosphorescence to Ir (ppy) 3 migrations, and when using Alq3, to Ir (ppy) 3 migrations, itself does not fluoresce Alq3 energy.
In addition, under the situation of BAlq, (Almq2) 20, all can not obtain luminous from material of main part and guest materials.Therefore think, though energy once to the guest materials migration because the triplet state energy level of material of main part is inappropriate, the energy that produces once more to material of main part moves again, through no radiative process and heat inactivation.
Therefore, when using phosphorescence class guest materials, wish to use the material of main part that the guest materials that uses is had suitable singlet, triplet state energy level.
Formation has the organic EL of following structure, promptly omits the hole injection layer among Fig. 1, and appends electron injecting layer.Having formed by thickness is on the glass substrate of the anode formed of the ITO of 150nm, adopts vacuum vapour deposition, in vacuum degree 4.0 * 10
-4Laminated each film under the Pa.At first form NPB as hole transmission layer with the evaporation rate of 1.0 /s on ITO, thickness is 60nm.
Then from different vapor deposition source all with the evaporation rate of 1.0 /s evaporation compound 12 and Ir (ppy) 3 on hole transmission layer simultaneously, forming thickness is the luminescent layer of 25nm.At this moment.Form Alq3 as electron transfer layer with the evaporation rate of 1.0 /s then, thickness is 50nm.Form lithium fluoride (LiF) as electron injecting layer with the evaporation rate of 0.5 /s on electron transfer layer again, thickness is 0.5nm.At last, form aluminium (Al) as electrode with the evaporation rate of 15 /s on electron injecting layer, thickness is 170nm, thereby makes organic EL.
Except from different vapor deposition source with the evaporation rate of 1.0 /s simultaneously on hole transmission layer evaporation compound 33 and Ir (ppy) 3 so that the concentration of Ir (ppy) 3 is 7.0%, forming thickness is outside the luminescent layer of 25nm, makes organic EL by the mode identical with embodiment 1.
When on the organic EL that embodiment 1～2 obtains, connecting external power source and applying direct voltage, confirm that it has the characteristics of luminescence as shown in table 3.In the table 3, brightness, voltage and luminous efficiency show at 10mA/cm
2Under value.The maximum wavelength of element luminescent spectrum is 517nm as can be known, has obtained from Ir (ppy)
3Luminous.
Comparative example 1
Except using HMTPD as hole transmission layer, use outside the principal component of TAZ as luminescent layer, make organic EL by the mode identical with embodiment 1.
Comparative example 2
Except using the principal component of TAZ, make organic EL by the mode identical with embodiment 1 as luminescent layer.Similarly to Example 1 evaluation result is shown in table 3 in the lump.
Table 3
| Brightness (cd/m 2) | Voltage (V) | Vision luminous efficiency (1m/W) | |
| | 2279 | 8.9 | 8.1 |
| | 2279 | 9.0 | 8.0 |
| Comparative example 1 | 2050 | 13.2 | 4.9 |
| Comparative example 2 | 1270 | 9.5 | 4.2 |
Organic electroluminescent device of the present invention makes can carry out high brightness, high efficiency luminous under low-voltage, and can obtain the little element of deterioration when high temperature is preserved.Therefore, organic electroluminescent 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), vehicle-mounted display element, mobile phone show and utilized the feature of planar luminous body, the present invention has very high technological value.
Claims (3)
1. organic electroluminescent device, described organic electroluminescent device is formed with the organic compound thin film layer that comprises luminescent layer between pair of electrodes, between luminescent layer and anode, has hole transmission layer, between luminescent layer and negative electrode, has electron transfer layer, between electron transfer layer and luminescent layer, do not have hole blocking layer, it is characterized in that, luminescent layer contains: as the compound shown in the following general formula (I) of material of main part, and be selected from ruthenium as containing of guest materials, rhodium, palladium, silver, rhenium, osmium, iridium, the metal-organic complex of at least a metal in platinum and the gold
In the formula, R
1～R
8Represent that independently of one another hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, amino, amide groups, alkoxy carbonyl group, carboxyl, alkoxyl maybe can have substituent aromatic group, Z represents to have substituent alkyl, group shown in aromatic heterocycle, diarye silyl or the following formula (II)
R
9～R
16Represent that independently of one another hydrogen atom, alkyl, aralkyl, alkenyl, cyano group, amino, amide groups, alkoxy carbonyl group, carboxyl, alkoxyl maybe can have substituent aromatic group.
2. the described organic electroluminescent device of claim 1 is characterized in that: in luminescent layer, contain the compound shown in the following general formula (III) as material of main part,
In the formula, R
1～R
16Identical with formula (I) with formula (II).
3. claim 1 or 2 described organic electroluminescent devices, wherein, guest materials is green phosphorescent luminiferous three (2-phenylpyridine) iridium complex.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101298442B (en) * | 2007-04-30 | 2010-07-07 | 中国科学院化学研究所 | Acidamide compound based on 2-(2'-hydroxyphenyl) benzoxazole, preparation and use thereof |
| CN101816085B (en) * | 2007-08-10 | 2013-04-17 | 株式会社丰田自动织机 | Electrode for secondary battery and method for producing the same |
| CN104835917A (en) * | 2008-11-17 | 2015-08-12 | 株式会社半导体能源研究所 | Light-emitting element, light-emitting device and electronic device |
| CN114920781A (en) * | 2007-05-10 | 2022-08-19 | 通用显示公司 | Metal organic compound having host and dopant functions |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW585895B (en) * | 1999-09-02 | 2004-05-01 | Nippon Steel Chemical Co | Organic EL material |
| JP4251553B2 (en) * | 2002-03-29 | 2009-04-08 | パイオニア株式会社 | Organic electroluminescence device |
-
2005
- 2005-03-04 CN CN200580008340A patent/CN100591184C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101298442B (en) * | 2007-04-30 | 2010-07-07 | 中国科学院化学研究所 | Acidamide compound based on 2-(2'-hydroxyphenyl) benzoxazole, preparation and use thereof |
| CN114920781A (en) * | 2007-05-10 | 2022-08-19 | 通用显示公司 | Metal organic compound having host and dopant functions |
| CN101816085B (en) * | 2007-08-10 | 2013-04-17 | 株式会社丰田自动织机 | Electrode for secondary battery and method for producing the same |
| CN104835917A (en) * | 2008-11-17 | 2015-08-12 | 株式会社半导体能源研究所 | Light-emitting element, light-emitting device and electronic device |
| CN104835917B (en) * | 2008-11-17 | 2018-09-07 | 株式会社半导体能源研究所 | Light-emitting component, light-emitting device and electronic equipment |
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