Embodiment
Organic light emitting apparatus of the present invention is the device with anode, negative electrode, luminescent layer and two hole transmission layers.
This luminescent layer is only formed by organic compound.Perhaps, this luminescent layer includes organic compounds.
Any other layer except that this luminescent layer and two hole transmission layers can be inserted between this anode and the negative electrode.Any other layer " of term " is meant electron injecting layer, electron transfer layer or carrier barrier layer.
In these two hole transmission layers, the hole transmission layer of close anode is first hole transmission layer, and the hole transmission layer of close luminescent layer is second hole transmission layer.
This first hole transmission layer have at least contain two or more nitrogen-atoms tertiary amine compound as key component.This means that this first hole transmission layer can only be formed by the tertiary amine compound that contains two or more nitrogen-atoms as key component.
The content (wt%) that contains the tertiary amine compound of two or more nitrogen-atoms in this first hole transmission layer is preferably 50wt% or as many as 100wt% or lower more, more preferably 90wt% or more as many as 100wt% or lower, or even more preferably 100wt%.
This contains the tertiary amine non-annularity tertiary amine preferably of the tertiary amine compound of two or more nitrogen-atoms.
In addition, consider that from the reduction and the durability aspect of the voltage that drives this device the material that is ready to use in this first hole transmission layer preferably has the hole mobility bigger than the material that is ready to use in this second hole transmission layer.Generally speaking, by the tertiary amine compound that contains two or more nitrogen-atoms form the layer mobility be lower than by the tertiary amine compound that contains a nitrogen-atoms forms layer mobility.Therefore, can keep lower in order to make the voltage that drives this device, the mobility of first hole transmission layer is preferably greater than the mobility of second hole transmission layer.
At this, hole mobility can be measured by the transient current measurement according to flight time (TOF) method.At this, get 500 (V/cm)
1/2The subduplicate value of applied voltage as this hole mobility.
This second hole transmission layer have at least contain a nitrogen-atoms tertiary amine compound as key component.This means that this second hole transmission layer can only be formed by the tertiary amine compound that contains a nitrogen-atoms as key component.In addition, except this contains the tertiary amine compound of a nitrogen-atoms, this second hole transmission layer can comprise any other nonnitrogenous atom and have the compound of wide energy gap.
The content that contains the tertiary amine compound of a nitrogen-atoms in this second hole transmission layer is preferably 50wt% or as many as 100wt% or lower more, more preferably 90wt% or more as many as 100wt% or lower, or even more preferably 100wt%.
This contains the tertiary amine non-annularity tertiary amine preferably of the tertiary amine compound of a nitrogen-atoms.
The above-mentioned non-annularity tertiary amine of the tertiary amine compound that first and second hole transmission layers have is separately represented not keyed jointing and do not form the tertiary amine of ring each other of its substituting group.When the substituting group of this tertiary amine not each other during keyed jointing, the degree of freedom of the rotation of molecular structure improves, thereby can more easily design the molecule with short conjugate length.As a result, under the situation of the tertiary amine compound that is ready to use in first hole transmission layer, the energy gap of this tertiary amine compound enlarges, and can prevent to absorb again.
In addition, under the situation of the tertiary amine compound that is ready to use in second hole transmission layer, the energy gap of this tertiary amine compound enlarges, and can effectively charge carrier and/or exciton be trapped in the luminescent layer.
In addition, the non-cyclic amine structure has the hole conductivity higher as carbazole than cyclic amine structure example.Therefore, use material can reduce the voltage of drive unit with non-annularity tertiary amine skeleton.For above-mentioned reasons, this tertiary amine non-annularity tertiary amine preferably.
In organic light emitting apparatus of the present invention, this first hole transmission layer has high hole transport performance and in improvement the hole is played a role from the aspect of performance that anode injects organic layer, and reason is that this layer comprises tertiary amine compound.
In addition, this second hole transmission layer has the high hole transmission performance, because this layer comprises tertiary amine compound.In addition, this tertiary amine compound has short conjugate length, because this compound contains a nitrogen-atoms.In addition, this compound plays the effect of capturing charge carrier and/or exciton in luminescent layer, because this compound has wide energy gap.
In view of mentioned above, the present inventor thinks that the existence of first hole transmission layer reduces the voltage that drives this device, and the existence of second hole transmission layer improves external quantum efficiency.
In addition, the energy gap of the tertiary amine compound that contains a nitrogen-atoms in this second hole transmission layer preferably has the energy gap length of the compound " of high-load than the " in this luminescent layer.When this second hole transmission layer also comprised another kind of compound (for example non-amines), the energy gap of this another kind compound also preferably had the energy gap length of the compound " of high-load than this ".The compound " that term as used herein " has high-load is meant material of main part.That is, in this case, this luminescent layer is by as the material of main part of key component and the layer that forms as the guest materials of helper component.
In the time can arranging compound based on their energy gap as mentioned above, the hole obtains promoting to the injection of luminescent layer, and can prevent that electronics from leaking to second hole transmission layer.Should be noted that energy gap can be brought in mensuration by the spectrum of measuring ultraviolet and visible absorption spectrum.
In addition, luminescent layer is mainly by the ionization potential Ip (1) of its compound that forms, first hole transmission layer mainly mainly preferably satisfies following relation by the ionization potential Ip (3) of its compound that forms by the ionization potential Ip (2) and second hole transmission layer of its compound that forms: Ip (2)<Ip (3)<Ip (1).
Ionization potential can be by for example UV photoelectron spectrometry (UVPES) (UPS), any other electronic spectrum method (for example by RIKENKIKICO., the measuring instrument of the AC-1 by name that LTD makes), or measure oxidation potential by cyclic voltammetry and measure.
As the tertiary amine compound with a nitrogen-atoms that is ready to use in second hole transmission layer, the tertiary amine compound of being represented by following general formula (1) shows below:
Wherein: Ar
11The arbitrary place in 2-to 4-position and the replacement or the unsubstituted fluorenyl of the N keyed jointing shown in the above-mentioned general formula (1) are treated in expression; Ar
12Expression aryl or heterocyclic radical, and in aryl and the heterocyclic radical each can have substituting group; R
11To R
19Be selected from the substituting group group that constitutes by hydrogen atom, alkyl, aralkyl, aryl, heterocyclic radical, cyano group and halogen independently of one another; Substituting group in this substituting group group can have substituting group; And R
11To R
19In any two each other keyed jointing to form ring.
In the compound of each free general formula (1) expression, the 4-aminofluorene compound is the tertiary amine compound that contains a nitrogen-atoms that preferably is ready to use in this second hole transmission layer.This 4-aminofluorene compound has the sterically hindered and shorter conjugate length higher than any other compound, because tertiary amine is replaced by fluorene group on the 4-position.This 4-aminofluorene compound is the hole mobile material with wide energy gap and high glass-transition temperature.As in these cases, this compound has the influence of expansion to the energy gap of this second hole transmission layer.In addition, in second hole transmission layer, use material to help improving the durability of this device, because this use makes the film forming stabilisation of this layer with high glass-transition temperature.
Show below by the substituent instantiation in the compound of above-mentioned general formula (1) expression.
The example of alkyl comprises methyl, ethyl, n-pro-pyl, isopropyl, normal-butyl, the tert-butyl group, sec-butyl, octyl group, 1-adamantyl and 2-adamantyl.
The example of aralkyl comprises benzyl and phenethyl.
The example of aryl comprise phenyl, naphthyl, pentalene base, indenyl, Azulene base, anthryl, pyrenyl, indacenyl, acenaphthenyl, phenanthryl, phenalenyl, fluoranthene base, acephenanthryl, aceanthryl, benzo (9,10) phenanthryl,
Base, aphthacene base, perylene base, pentacene base, xenyl, terphenyl and fluorenyl.
The example of heterocyclic radical comprises thienyl, pyrrole radicals, pyridine radicals, oxazolyl, oxadiazole base, thiazolyl, thiadiazolyl group, terthienyl base, carbazyl, acrydinyl and phenanthroryl.
In addition, the substituent example that can have comprises: alkyl is methyl, ethyl and propyl group for example; Aralkyl is benzyl and phenethyl for example; Aryl is phenyl and xenyl for example; Heterocyclic radical is thienyl, pyrrole radicals and pyridine radicals for example; Amino is dimethylamino, diethylamino, dibenzyl amino, diphenyl amino, xylyl amino and two fennel ether amino for example; Alkoxyl is methoxyl group, ethyoxyl, propoxyl group and phenoxy group for example; Cyano group; With halogen atom for example fluorine, chlorine, bromine and iodine.
That the example of halogen radical comprises is fluorine-based, chloro, bromo and iodo.
Instantiation by the compound of above-mentioned general formula (1) expression shows below.Yet, the invention is not restricted to these examples.In addition, the Ar shown in any among the example compound 1-68
11Can with the Ar shown in any among the example compound 1-68
12In conjunction with.
Fig. 1 and 2 shows the preferred embodiment of organic light emitting apparatus of the present invention separately.
Fig. 1 is the cutaway view that shows an example of organic light emitting apparatus of the present invention.Reference number 1 expression base material; 2, anode; 5-1, first hole transmission layer; 5-2, second hole transmission layer; 3, luminescent layer; 6, electron transfer layer and 4, negative electrode.
Fig. 2 is the cutaway view that shows another example of organic light emitting apparatus of the present invention.Fig. 2 shows the structure different with the structure of the organic light emitting apparatus shown in Fig. 1, in Fig. 2, two hole transmission layers of lamination like this are about to hole injection layer 7 and are inserted between the anode 2 and the first hole transmission layer 5-1 performance with further raising injected hole as extra play.In this case, the hole is very good from the performance that anode injects luminescent layer, and can realize driving the further reduction of the voltage of this device.In addition, this structure in, be used for blocking hole or exciton escape into negative electrode 4 one sides the layer (a hole/exciton-blocking layers 8) be inserted between luminescent layer 3 and the electron transfer layer 6.This structure can effectively improve the luminous efficiency of this device, because use the compound with high ionization potential in this hole/exciton-blocking layers 8.Other reference number shown in Fig. 2 represent with Fig. 1 in identical member.
Should be noted that Fig. 1 and 2 only shows basic device construction, the invention is not restricted to these structures.Organic light emitting apparatus can adopt any in the various layer structure, for example wherein provides the structure of insulating barrier for the interface between electrode and the organic layer and the structure of adhesive phase or interfering layer wherein is provided for this interface.
In organic light emitting apparatus of the present invention, the layer of forming by compound of the present invention and by layer forming by the following method that another kind of organic compound is formed.Generally speaking, form film by vacuum vapor deposition method, ionization vapor deposition method, sputter or plasma.Perhaps, form film by the following method: the material that will be used for this film is dissolved in suitable solvent; Apply this solution by known painting method (for example spin coating, dipping, casting method, LB method or ink-jet method).Especially, when forming film by painting method, the formation that can combine with suitable resin glue of this film.
The material that is used for anode desirably has big as far as possible work function, and the example of operable material comprises: metallic element is gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium and tungsten for example, or the alloy of this metallic element; With metal oxide for example tin oxide, zinc oxide, indium oxide, tin indium oxide (ITO) and indium zinc oxide.Also can use conducting polymer for example polyaniline, polypyrrole, polythiophene or polyphenylene sulfide.Each of those electrode substances can be used separately, or in them two or more can be used in combination.In addition, anode can be made of individual layer, perhaps can be made of multilayer.
On the other hand, the material that is used for negative electrode desirably has little work function, and the example of operable material comprises: metallic element is lithium, sodium, potassium, calcium, magnesium, aluminium, indium, ruthenium, titanium, manganese, yttrium, silver, lead, tin and chromium for example; With the alloy of two or more compositions of each free this metallic element for example lithium indium alloy, Na-K alloy, magnesium silver alloy, aluminium lithium alloy, almag and magnesium indium alloy.Also can use for example tin indium oxide (ITO) of metal oxide.Each of those electrode substances can be used separately, or in them two or more can be used in combination.In addition, negative electrode can be made of individual layer, perhaps can be made of multilayer.
Be used for base material of the present invention and be not particularly limited, and use opaque base material for example metal base or ceramic base material, perhaps for example glass, quartz or plastic sheet of transparent base.In addition, in this base material, can use colour filter film, fluorescence color conversion colour filter film, dielectric reflections film etc. coloured light to be arranged with control.
Should be noted that the device of being produced can be provided with protective layer or sealant contacts with for example oxygen or moisture so that prevent this device.The example of this protective layer comprises: diamond thin; The inorganic material film of making by for example metal oxide or metal nitride; Thin polymer film is fluororesin, Parylene, polyethylene, silicone resin or polystyrene resin for example; With the light curable resin.In addition, itself can be coated with glass, airtight film or metal this device, and this device itself can be packed with suitable sealing resin.
Perhaps, whether organic light emitting apparatus of the present invention can be connected so that control this organic light emitting apparatus luminous with the thin-film transistor for preparing on base material (TFT).
This device can be installed on the display so that be used as the pixel of viewing area.
Hereinafter, will the present invention more specifically be described via embodiment.Yet, the invention is not restricted to those embodiment.
(embodiment 1)
Organic light emitting apparatus with structure as shown in Figure 1 prepares by the following method.
By method for sputtering make tin indium oxide (ITO) form thickness be the film of 120nm with as the anode on the glass baseplate of base material 12, and with gains as transparent, conductive support base material.Sequentially in acetone and isopropyl alcohol (IPA), these gains are carried out ultrasonic waves for cleaning, in IPA, boil cleaning then, then dry.In addition, will experience the gains of UV/ ozone clean as transparent, conductive support base material.
By using the compound represented by following general structure 1 to prepare chloroformic solution, satisfy this compound concentrations and become 0.2wt% as hole mobile material.
This solution is dripped on the above-mentioned ITO electrode, and this integral body is carried out spin coating, initial under the revolution of 500RPM 10 seconds, then 1, following 1 minute of the revolution of 000RPM, thus form film.Then, with in the vacuum drying oven of gains under 80 ℃ dry 10 minutes, thereby the solvent in this film is removed fully.The formed first hole transmission layer 5-1 has the thickness of 15nm.
In addition, by the compound 2 that the steam deposition is represented by following structural formula, be the second hole transmission layer 5-2 of 20nm thereby form thickness.
Next, by the compound 3 that will represent by following structural formula with to provide thickness by the compound 4 that following structural formula is represented by the steam codeposition on this hole transmission layer 5-2 be the luminescent layer 3 of 25nm.The condition that forms this layer comprises 1.0 * 10
-4Film deposition rate when vacuum degree the when steam of Pa deposits and the steam of 0.2 to 0.3nm/ second deposition.
In addition, by vacuum vapor deposition method with 2,9-[2-(9,9 '-dimethyl fluorenyl)]-1, it is the electron transfer layer 6 of 25nm that the 10-phenanthroline forms thickness.The condition that forms this layer comprises 1.0 * 10
-4Film deposition rate when vacuum degree the when steam of Pa deposits and the steam of 0.2 to 0.3nm/ second deposition.
Next, by vacuum vapor deposition method lithium fluoride (LiF) being formed thickness on previous organic layer is the film of 0.5nm.In addition, on gains by vacuum vapor deposition method provide thickness be the aluminium film of 100nm as electron injection electrode (negative electrode 4), thereby prepared organic light emitting apparatus.Vacuum degree during this steam deposition is 1.0 * 10
-4Pa forms film with lithium fluoride, and under the film formation speed of 1.0 to 1.2nm/ seconds aluminium is formed film under the 0.05nm/ film formation speed of second.
In dry air atmosphere, cover the gained organic El device with the protectiveness glass plate and with acrylic resin-based adhesive seal so that can prevent that this equipment is owing to adsorption moisture damages.At this, the energy gap of compound 2 is greater than the energy gap of compound 4.In addition, aspect the numerical value of ionization potential, compound 1, compound 2 and compound 4 following arrangements: compound 1<compound 2<compound 4.
Device luminous efficiency with 5.31m/W under the applied voltage of 4V of observing this embodiment is luminous.In addition, observing the emission of this device has the cie color coordinate (x y) is the blue light of (0.15,0.17) and good color purity.
In addition, under nitrogen atmosphere, applied voltage 100 hours to this device.As a result, observe this device good light of emission continuously.
Compound 1
Compound 2
Compound 3
Compound 4
(embodiment 2)
With the method preparation facilities the same with embodiment 1, difference is: use compound 5 to replace compounds 1; Use compound 6 to replace compound 3.
At this, the energy gap of compound 2 is greater than the energy gap of compound 4.In addition, aspect the numerical value of ionization potential, compound 2, compound 4 and compound 5 following arrangements: compound 5<compound 2<compound 4.This first hole transmission layer has the thickness of 13nm.The device of observing this embodiment under the applied voltage of 4V with 3.9mA/cm
2Current density, 331cd/m
2Light emission brightness and the luminous efficiency of 6.71m/W luminous.In addition, observe the good blue light of emission.
Compound 5
Compound 6
(comparative example 1)
Preparation only has the organic light emitting apparatus of a hole transmission layer.
In order to form hole transmission layer 5, preparation concentration is the chloroformic solution of the compound 5 of 0.24wt%.
This solution is dripped on the above-mentioned ITO electrode, and these gains are carried out spin coating, at first under the revolution of 500RPM 10 seconds, then 1, following 1 minute of the revolution of 000RPM, thus form film.Then, in the vacuum drying oven under 80 ℃ dry this film 10 minutes so that the solvent in this film is removed fully.Formed hole transmission layer 5 has the thickness of 33nm.When the square root of applied voltage is 500 (V/cm)
1/2The time, the hole mobility of this hole transmission layer is 1.4 * 10
-3Cm
2/ Vs.
In addition, with preparing luminescent layer, electron transfer layer and A1 electrode separately with embodiment 2 the same methods.
Apply the voltage of 4.0V to the device of such acquisition, simultaneously with this ITO electrode (anode 2) as positive electrode, and with this A1 electrode (negative electrode 4) as negative electrode.As a result, observe this device with 3.0mA/cm
2Current density, 83.3cd/m
2Light emission brightness and the luminous efficiency of 2.21m/W luminous.In addition, observe the light emission.
(comparative example 2)
In order to form hole transmission layer 5, preparation concentration is the chloroformic solution of the compound 2 of 0.24wt%.
This solution is dripped on the above-mentioned ITO electrode, and these gains are carried out spin coating, at first under the revolution of 500RPM 10 seconds, then 1, following 1 minute of the revolution of 000RPM, thus form film.Then, the solvent of in vacuum drying oven, consequently fully removing in this film in 10 minutes at 80 ℃ of down dry these films.Formed hole transmission layer 5 has the thickness of 33nm.When the square root of applied voltage is 500 (V/cm)
1/2The time, the hole mobility of this hole transmission layer is 3.3 * 10
-4Cm
2/ Vs.
In addition, with preparing luminescent layer, electron transfer layer and A1 electrode separately with embodiment 2 the same methods.
Apply the voltage of 4.0V to the device of such acquisition, simultaneously with this ITO electrode (anode 2) as positive electrode, and with this A1 electrode (negative electrode 4) as negative electrode.As a result, observe this device with 2.5mA/cm
2Current density, 174cd/m
2Light emission brightness and the luminous efficiency of 5.51m/W luminous.In addition, observe blue emission.
As mentioned above, the device of embodiment 2 is compared in the following areas with 2 device with comparative example 1 and is improved: the improvement when (1) drives under constant voltage aspect electric current raising (this means that device can drive under low-voltage) and (2) luminous efficiency.In addition, as can finding out from embodiment 2 and comparative example 1 and 2, when the hole mobility of first hole transmission layer during greater than second hole transmission layer, can be at drive unit under the low-voltage.In this case, when carrying out the driving of this device with low-voltage, 5 * 10
-4Cm
2/ Vs or higher mobility are wished.
(embodiment 3)
With with embodiment 2 in the same method preparation facilities, difference is to use compound 7 to replace the compound 2 of embodiment 2.
The device of observing this embodiment under the applied voltage of 4V with 3.4mA/cm
2Current density, 202cd/m
2Light emission brightness and the luminous efficiency of 4.71m/W luminous.In addition, observe the good blue light of emission.
At this, the energy gap of compound 7 is greater than the energy gap of compound 4.In addition, aspect the numerical value of ionization potential, compound 4, compound 5 and compound 7 following arrangements: compound 5<compound 7<compound 4.
(embodiment 4)
With with embodiment 2 in the same method preparation facilities, difference is to use compound 8 to replace the compound 2 of embodiment 2.
When the square root of applied voltage is 500 (V/cm)
1/2The time, the hole mobility of the hole transmission layer that is formed by compound 8 is 4.5 * 10
-4Cm
2/ Vs.
The device of observing this embodiment under the applied voltage of 4V with 5.2mA/cm
2Current density, 332cd/m
2Light emission brightness and the luminous efficiency of 5.01m/W luminous.In addition, observe the good blue light of emission.
At this, the energy gap of compound 8 is greater than the energy gap of compound 4.In addition, aspect the numerical value of ionization potential, compound 4, compound 5 and compound 8 following arrangements: compound 5<compound 8<compound 4.
Compound 7
Compound 8
Compound 9
Compound 10
Compound 11
(embodiment 5)
With the method preparation facilities the same with embodiment 2, difference is: use compound 10 to replace compounds 4; Use compound 9 to replace compound 3; Replace 2 by use compound 11,9-[2-(9,9 '-the dimethyl fluorenyl)]-1, it is the electron transfer layer 6 of 50nm that 10-phenanthroline compound forms thickness.
The device of observing this embodiment under the applied voltage of 4V with 0.04mA/cm
2Current density, 17.4cd/m
2Light emission brightness and the luminous efficiency of 34.21m/W luminous.In addition, observe green emission with good color purity.
At this, the energy gap of compound 2 is greater than the energy gap of compound 10.In addition, aspect the numerical value of ionization potential, compound 2, compound 5 and compound 10 following arrangements: compound 5<compound 2<compound 10.
The application requires in the rights and interests of the Japanese patent application No. 2007-040899 of the Japanese patent application No. 2006-116903 of submission on April 20th, 2006 and submission on February 21st, 2007, and therefore these documents are incorporated herein by reference in full at this.