WO2013011883A1 - Organic light-emitting layer material and organic light-emitting element - Google Patents

Abstract

Provided are an organic light-emitting material and organic light-emitting element that make it easy to control the quantity of a dopant to provide, and can emit white light. The organic light-emitting element comprises a first electrode, a second electrode, and a light-emitting layer placed between the first electrode and the second electrode. In the organic light-emitting element, the first electrode, the light-emitting layer and the second electrode are formed sequentially on top of a substrate, the light-emitting layer contains a host and multiple dopants, and the multiple dopants have absorption peaks at nearly the same position, and emission peaks at different positions.

Description

Organic light emitting layer material and organic light emitting device

The present invention relates to an organic light emitting layer material, a coating liquid for forming an organic light emitting layer using the organic light emitting layer material, an organic light emitting element using the coating liquid for forming the organic light emitting layer, and a light source device using the organic light emitting element .

An organic white light emitting device having a single light emitting layer so far includes an organic light emitting layer having a single layer light emitting layer formed of a composition containing at least (a) a polymer and (b) a luminescent center forming compound between electrodes. An EL device, wherein an electron transporting material and a hole transporting material are included in a well-balanced manner in the composition, and the polymer exhibits its own emission color of blue or a shorter wavelength than that. It is.

Two or more of the luminescent center-forming compounds are present in the form of molecular dispersion in the polymer, and each luminescent center-forming compound emits light alone, and the color light as the whole of the organic EL element is white light Patent Document 1 reports a single layer type white light emitting organic EL device in which two or more kinds of the above-mentioned luminescent center forming compounds are used in combination so as to be visible. Other documents include Patent Documents 2 to 4.

In Patent Document 2, an organic electroluminescent device having a pair of electrodes and at least one organic layer including a light emitting layer between the electrodes on a substrate, is a branched alkyl in any layer of the organic layer. An organic electroluminescent device characterized in that it contains a metal complex having a group is disclosed.

Patent Document 3 discloses a host material for an organic EL element containing an iridium complex.

In Patent Document 4, b (b is an integer of 1 to (a + 2)) is selected on a basic skeleton in which a (a is an integer of 3 or more) aromatic six-membered rings are linked to the m-position. And -NR ¹ R ² group (R ¹ and R ² are each independently an arbitrary substituent), and all of the -NR ¹ R ² groups are to the m-linkage site in the aromatic 6-membered ring Or an organic compound bonded to the m-position (however, the aromatic 6-membered ring may have a substituent in addition to the —NR ¹ R ² group, and a plurality of aromatic groups contained in one molecule 6 Member rings may be the same ring or different rings, and a plurality of -NR ¹ R ² groups contained in one molecule may be the same or different groups. ) Is disclosed.

JP 09-063770 A JP, 2010-185068, A JP, 2006-290988, A JP 2005-68068 A

In the conventional organic light emitting device, there is a problem that the dopant concentration is very low and it is difficult to control the concentration of the dopant. In addition, when the concentration of the dopant is controlled, the light emission efficiency is lowered, and there is a problem that high efficiency light emission can not be obtained. None of the above-mentioned Patent Documents 1 to 4 disclose a method for solving the above-mentioned decrease in luminous efficiency.

The object of the present invention is to provide an organic light emitting layer material capable of simply controlling the concentration of a dopant, a coating liquid for forming an organic light emitting layer using the organic light emitting layer material, an organic light emitting device using a coating liquid for forming the organic light emitting layer and It is providing a light source device using an organic light emitting element.

In order to solve the above-mentioned subject, the present invention is the organic light emitting element which has the luminous layer arranged between the 1st electrode, the 2nd electrode, and the 1st electrode and the 2nd electrode. ,
The first electrode, the light emitting layer, and the second electrode are formed in this order on the substrate, and the light emitting layer includes a host and a plurality of dopants, and the absorption peaks of the plurality of dopants are substantially at the same position. It is an object of the present invention to provide an organic light emitting device characterized in that the peaks are at different positions. That is, in selecting a plurality of dopants to be added to the host material, the light absorption peaks of the plurality of dopants are at substantially the same position (wavelength or energy level eV), but the emission peak is blue, red or green wavelength or By selecting one at an energy level, the transfer of energy from a high energy level dopant (for example blue) to a low energy level (for example green) is suppressed, for example to prevent the blue emission peak from being reduced Can. Therefore, the remarkable effect is obtained that the initial emission intensity of each dopant can be obtained without finely controlling the amount of the dopant.

The present invention emits energy-absorbing dopant (for example, emits blue light) by appropriately selecting the absorption peak and the emission peak of a plurality of dopants to be added to the host (the absorption wavelength and the emission wavelength are separated). The dopants suppress energy transfer to other dopants (for example, dopants that emit red light), and the emission peak of a particular dopant is not weakened. Therefore, as in the prior art, it is not necessary to finely adjust the concentration of the dopant so that the light emission intensity of each dopant has a sufficient value while considering the above-described energy transfer.

According to the present invention, an organic light emitting layer material capable of easily controlling the concentration of a dopant and realizing white light emission with high color temperature (high blue light emission peak intensity), a coating liquid for forming an organic light emitting layer using an organic light emitting layer material An organic light emitting device using a coating liquid for forming an organic light emitting layer and a light source device using the organic light emitting device can be provided. That is, the energy transfer from the dopant of short wavelength emission (blue emission) to the dopant of long wavelength emission is reduced. This means that the emission component (blue component) of the short wavelength increases in the entire emission spectrum, and the color temperature becomes high.

It is a light source device sectional view in one embodiment of the present invention. It is sectional drawing of the organic light emitting element in one embodiment of this invention.

Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

The main ones of the embodiments according to the present invention are as follows.

(1) An organic light emitting device having a light emitting layer disposed between a first electrode, a second electrode, and the first electrode and the second electrode,
The first electrode, the light emitting layer, and the second electrode are formed in this order on a substrate, the light emitting layer includes a host and a plurality of dopants, has three types of light emitting dopants, and emits light at the shortest wavelength. What is claimed is: 1. An organic light emitting device comprising a dopant having a wavelength difference between an emission peak and an absorption peak different from the wavelength difference between an emission peak and an absorption peak of a light emitting dopant. By configuring as described above, the energy transfer from the short wavelength light emitting dopant to the long wavelength light emitting dopant is reduced, and it is not necessary to make the amount of the long wavelength dopant very small.

The term "the absorption peaks are located at substantially the same position" means that the maximum value of the difference between the absorption peaks of the respective dopants is within 0.2 eV. Further, that the emission peaks are at different positions means that the emission peaks of blue, red and green are different.

(2) An organic light emitting device comprising a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode,
The first electrode, the light emitting layer, and the second electrode are sequentially formed on a substrate, the light emitting layer includes a host and a plurality of dopants, and the first light emitting dopant in the light emitting layer is in the light emitting layer. An organic light emitting device having a concentration gradient, the highest concentration portion being present on the light emitting layer surface side, and the other two dopants having substantially the same absorption peak positions but different emission peak positions.

With the above configuration, the energy transfer between the dopants is reduced, and the amount of dopant does not need to be very small.

First, having a concentration gradient reduces energy transfer with other dopants. In addition, since the absorption position is the same and the light emission position is different, the overlap between the light emission and the absorption decreases, and the energy transfer is reduced.

(3) An organic light emitting device comprising a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode,
The first electrode, the light emitting layer, and the second electrode are sequentially formed on a substrate, the light emitting layer includes a host and a plurality of dopants, and the first light emitting dopant in the light emitting layer is in the light emitting layer. An organic light emitting device having a concentration gradient, the highest concentration portion being present on the light emitting layer surface side, and the other two dopants having substantially the same absorption peak positions but different emission peak positions.

The above configuration achieves the object of the present invention for the reason described in (2) above.

(4) An organic light emitting device comprising a light emitting layer disposed between a first electrode, a second electrode, and the first electrode and the second electrode,
The first electrode, the light emitting layer, and the second electrode are sequentially formed on a substrate, the light emitting layer includes a host and a plurality of dopants, and the light emitting dopant in the light emitting layer is represented by the following general formula (1) Organic light emitting device

In the general formula (1), Ar1 and Ar2 each represent an aromatic hydrocarbon or an aromatic heterocyclic ring.
Ar1 and Ar2 each have a hydrogen atom or a substituent represented by the following general formula (2). M represents an element of Groups 8, 9 or 10 in the periodic table. m and n each represent an integer of 1 to 3;
L represents an optionally substituted ligand.

L represents a ligand and may be substituted by the following substituent, which is a hydrogen atom, an alkyl group having 4 to 15 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 5 carbon atoms Or a fluoroalkyl group having 3 to 6 carbon atoms, or a substituent represented by the following general formula (2).

In the general formula (2), R 1 represents a hydrogen atom or a substituent, and the substituent is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an acyl having 1 to 5 carbon atoms A fluoroalkyl group having 1 to 6 carbon atoms.

In the above-described materials, concentration distribution occurs, or the absorption position is the same and the light emission position is different.

(5) An organic light emitting layer material comprising a host material and a plurality of dopants,
An organic light emitting layer material, wherein absorption peaks of the plurality of dopants are at substantially the same position, and light emission peaks are at different positions.

With the above configuration, the energy transfer between the dopants is reduced, and the amount of dopants does not have to be very small.

(6) Based on the mass of the host, each contains 0.05 to 50 mass% of the plurality of dopants and 0 to 50 mass% of the binder, and the absorption peaks of the plurality of dopants are approximately at the same position, Organic light emitting layer materials characterized in that they are at different positions.

With the above configuration, the energy transfer between the dopants is reduced, and the amount of dopants does not have to be very small.

Hereinafter, embodiments of the present invention will be described using the drawings and the like. The following description shows specific examples of the content of the present invention, and the present invention is not limited to these descriptions, and various modifications by those skilled in the art can be made within the scope of the technical idea disclosed herein. Changes and modifications are possible. Moreover, in all the drawings for explaining the present invention, what has the same function may attach the same numerals, and may omit explanation of the repetition.

In organic light emitting devices manufactured by the conventional application method, the green dopant concentration is as high as 0.02 mol% and the red dopant concentration is as high as 0.02 mol% and 0.015 mol% in order to suppress energy transfer from the blue dopant. And the concentration control of the dopant becomes difficult. In addition, sufficient light emission efficiency can not be obtained due to energy transfer between the respective dopants and insufficient carrier confinement in the light emitting region.

FIG. 1 is a cross-sectional view of an embodiment of a light source device according to the present invention. The light emitting portion is composed of the substrate 10, the lower electrode 11, the upper electrode 12, the organic layer 13, the bank 14, the reverse taper bank 15, the resin layer 16, the transparent sealing substrate 17 and the light extraction layer 18. The light extraction layer 18 may not be provided as the light emitting portion.

The substrate 10 is a glass substrate. Besides the glass substrate, a plastic substrate or a metal substrate provided with a suitable water permeability lowering protective film can also be used.

First, the lower electrode 11 is formed on the substrate 10. The lower electrode 11 is an anode. A laminate of a transparent electrode such as ITO or IZO and a reflective electrode such as Ag is used. Besides the laminate, Mo, Cr, a combination of a transparent electrode and a light diffusion layer, or the like can be used. Further, the lower electrode 11 is not limited to the anode, but can be used also for the cathode. In that case, Al, Mo, a laminate of Al and Li, an alloy such as AlNi, or the like is used. The lower electrode 11 described above is used by patterning on the substrate 10 by photolithography.

The upper electrode 12 is formed on the organic layer 13. The upper electrode 12 is a cathode. A laminate of a transparent electrode such as ITO or IZO and an electron injecting electrode such as MgAg or Li is used. Besides the laminate, an MgAg or Ag thin film can be used alone. In addition, when forming ITO or IZO by sputtering, a buffer layer may be provided between the upper electrode 12 and the organic layer 13 in order to reduce damage caused by sputtering. For the buffer layer, a metal oxide such as molybdenum oxide or vanadium oxide is used. When the lower electrode 11 is a cathode as described above, the upper electrode 12 is an anode. In that case, a transparent electrode such as ITO or IZO is used. The upper electrode 12 present in a specific light emitting part is connected to the lower electrode 11 of the light emitting part adjacent to the specific light emitting part. Thereby, a plurality of light emitting units can be connected in series. A light source device is formed by connecting a drive device to a plurality of light emitting units connected in series.

An organic layer 13 is formed on the lower electrode 11. The organic layer 13 may be a single layer structure of only a light emitting layer or a multilayer structure including any one or more of an electron injection layer, an electron transport layer, a hole transport layer and a hole injection layer.

The bank 14 covers the end of the lower electrode 11 and is formed to prevent a partial short circuit failure of the light emitting unit. As a material of the bank 14, photosensitive polyimide is preferable. However, it is not limited to photosensitive polyimide, and acrylic resin etc. can also be used. In addition, non-photosensitive materials can also be used.

The reverse taper bank 15 is used to prevent the upper electrodes 12 of the adjacent light emitting parts from conducting due to the reverse taper shape. It is preferable to use a negative photoresist as the reverse taper bank 15. In addition to the negative photoresist, various polymers and various polymers can be laminated.

A resin layer 16 is formed on the upper electrode 12. The resin layer 16 is used to seal the light emitting unit. Various polymers such as epoxy resin can be used. An inorganic passivation film can also be used between the upper electrode 12 and the resin layer 16 to improve the sealing performance.

The sealing substrate 17 is formed on the resin layer 16. The sealing substrate 17 is a glass substrate. Besides the glass substrate as the sealing substrate 17, a plastic substrate having an appropriate gas barrier film can also be used.

The light extraction layer 18 is formed on the sealing substrate 17. The light extraction layer 18 is used to efficiently extract the light emitted from the light emitting layer in the organic layer 13. As the light extraction layer 18, a film having scattering property and diffuse reflection property is used. The organic light emitting layer 13 is excited by a drive circuit 20 having a power supply and a wiring connecting the lower electrodes 11 to drive the light source device. It is essential that the organic layer 13 includes an organic light emitting layer.

FIG. 2 is a cross-sectional view of an organic white light emitting device according to an embodiment of the present invention. The organic white light emitting device has an upper electrode 12, a lower electrode 11, and an organic layer 13. The upper electrode 12 and the lower electrode 11 correspond to any one of the first electrode and the second electrode. The substrate 10, the lower electrode 11, the organic layer 13 and the upper electrode 12 are arranged in this order from the lower side of FIG. 2, and the organic white light emitting device of FIG. It is. The lower electrode 11 is a transparent electrode to be an anode, and the upper electrode 12 is a reflective electrode to be a cathode.
If the upper electrode 12 is a cathode and the lower electrode 11 is an anode, a top emission type element structure in which the upper electrode 12 is a transparent electrode may be used. The substrate 10 and the lower electrode 11, the lower electrode 11 and the organic layer 13, the organic layer 13 and the upper electrode 12 may be in contact with each other, and an inorganic buffer layer or an injection layer may be interposed between the layers. Examples of the inorganic buffer layer include vanadium oxide, molybdenum oxide and tungsten oxide.

The organic layer 13 may be a single layer structure of only the light emitting layer 3 or a multilayer structure including any one or more of the electron injection layer 9, the electron transport layer 8, the hole transport layer 2 and the hole injection layer 1. The electron injection layer 9 and the electron transport layer 8, the electron transport layer 8 and the light emitting layer 3, the light emitting layer 3 and the hole transport layer 2, the hole transport layer 2 and the hole injection layer 1 may be in contact with each other An inorganic buffer layer or an injection layer may be interposed therebetween.

The light emitting layer 3 contains a host and a dopant. The light emitting layer 3 is a layer in which electrons and holes injected from the upper electrode 12, the lower electrode 11, the electron transporting layer 8 or the hole transporting layer 2 recombine to emit light. The portion that emits light may be in the layer of the light emitting layer 3 or may be an interface between the light emitting layer 3 and a layer adjacent to the light emitting layer 3.

As a dopant, a fluorescent compound or a phosphorescent compound can be used. The dopant includes any one or more of a red dopant, a green dopant and a blue dopant.
The material for forming the light emitting layer 3 comprises a host, a red dopant, a green dopant and a blue dopant. When white light is emitted from the light emitting layer 3, as a material for forming the light emitting layer 3, a host, one containing a red dopant and a blue dopant, one containing a host, a red dopant and a green dopant, a host, a green dopant and a blue one It may contain a dopant. In the case of emitting light other than white light from the light emitting layer 3, a material for forming the light emitting layer 3 may include, for example, a host and a dopant of a single color.

The emission color of the red dopant, the emission color of the green dopant and the emission color of the blue dopant are different. "Emission color is different" means that the wavelength showing the maximum intensity in the PL spectrum of each dopant is different.

The light emitting layer 3 may contain a binder polymer. As the binder polymer, one or more of polycarbonate, polystyrene, acrylic resin, polyamide, gelatin and the like can be mentioned. By containing the binder polymer, the viscosity of the light emitting layer 3 can be increased, and the printability can be improved. In addition, the stability of the film of the light emitting layer 3 can be improved. The binder is preferably 0 to 100% by mass, and more preferably 1 to 50% by mass, with respect to the host. The host may be 0.1 to 10% by mass, preferably 0.5 to 5% by mass, and the dopant may be 0.05 to 5% by mass, preferably 0.075 to 2.5% by mass, based on the mass of the solvent. . However, in the case of the photosensitive layer material from which the solvent is removed, the mass of the dopant is 0.0005 to 50 mass%, and the binder is 0 to 50 mass% based on the mass of the host.

<Host>
A host is a material used to immobilize a dopant, which emits light after an excited state is formed by an electric field, and in general, the difference (band gap) between HOMO and LUMO is wider than that of the dopant. It is preferable to use a carbazole derivative, a fluorene derivative or an arylsilane derivative as a host. In order to obtain efficient light emission, it is preferable that the excitation energy of the host be sufficiently larger than the excitation energy of the blue dopant. The excitation energy is measured using an emission spectrum.

<Blue dopant>
The blue dopant has a maximum intensity of PL spectrum at room temperature between 400 nm and 500 nm. An Ir complex is used as the blue dopant. Further, various metal complexes such as Pd, Pt and Al, and organic materials such as styrylamines and triazine derivatives can also be used.

Excitation from the blue dopant in the case where the blue dopant and the dopant (a green dopant, a red dopant) whose wavelength showing the maximum intensity of the PL spectrum is longer than the blue dopant are present in the light emitting layer 3 and the green dopant or the red dopant is a surface dopant Since the energy transfer to the low energy green dopant and red dopant is suppressed, the molar concentration of the blue dopant in the solid content of the light emitting layer 3 is higher than the molar concentration of the green dopant and the red dopant in the solid content of the light emitting layer 3 It can be enlarged. Here, the surface dopant is a dopant which moves so as to have a high concentration region on the surface of the light emitting layer when the light emitting layer is formed.

<Green dopant>
The green dopant has a maximum intensity of PL spectrum at room temperature between 500 nm and 590 nm. An Ir complex is used as the green dopant. Further, various metal complexes such as Pd, Pt, Al and Zn, and organic materials such as coumarin dyes, quinacridones and triazine derivatives can also be used.

When a green dopant and a dopant (red dopant) whose wavelength showing the maximum intensity of PL spectrum is longer than the green dopant are present in the light emitting layer 3 and the red dopant is a surface dopant, from green dopant to red dopant having low excitation energy Since the energy transfer is suppressed, the molar concentration of the green dopant in the solid content of the light emitting layer 3 can be made larger than the molar concentration of the red dopant in the solid content of the light emitting layer 3.

<Red dopant>
The red dopant has a maximum intensity of PL spectrum at room temperature between 590 nm and 780 nm. An Ir complex is used for the red dopant. In addition, various metal complexes such as Pd, Pt, Al, Zn, DCM ([2-[(E) -4- (dimethylamino) styryl] -6-methyl-4H-pyran-4-ylidene] malononitrile), triazine Organic materials such as derivatives can also be used.

<Hole injection layer>
The hole injection layer 1 is used for the purpose of improving the luminous efficiency and the lifetime. Further, although not particularly essential, it is used for the purpose of alleviating the irregularities of the anode. The hole injection layer 1 may be provided in a single layer or a plurality of layers. The hole injection layer 1 is preferably a conductive polymer such as PEDOT (poly (3,4-ethylenedioxythiophene)): PSS (polystyrene sulfonate). Besides, polypyrrole-based and triphenylamine-based polymer materials can be used. Further, phthalocyanine compounds and starburst amine compounds which are often used in combination with a low molecular weight (weight average molecular weight of 10000 or less) material system are also applicable.

<Hole transport layer>
The hole transport layer 2 is used to transport holes injected from the anode to the light emitting layer. As the hole transport layer 2, a homopolymer or copolymer of fluorene, carbazole, arylamine or the like is used. As the copolymer, materials having a thiophene type or a pyrrole type as a skeleton can also be used. Further, polymers having a skeleton such as fluorene, carbazole, arylamine, thiophene or pyrrole in the side chain can also be used. In addition, the polymer is not limited, and a starburst amine compound, an arylamine compound, a stilbene derivative, a hydrazone derivative, a thiophene derivative and the like can be used. Moreover, you may use the polymer containing said material. Further, the present invention is not limited to these materials, and two or more of these materials may be used in combination.

<Electron transport layer>
The electron transport layer 8 is a layer that supplies electrons to the light emitting layer 3. The electron injection layer 9 and the hole blocking layer are also included in the electron transport layer 8 in a broad sense. The electron transport layer 8 may be provided in a single layer or a plurality of layers. Examples of the material of the electron transport layer 8 include bis (2-methyl-8-quinolinolato) -4- (phenylphenolato) aluminum (hereinafter referred to as BAlq) and tris (8-quinolinolato) aluminum (hereinafter , Alq3), Tris (2,4,6-trimethyl-3- (pyridin-3-yl) phenyl) borane (hereinafter referred to as 3TPYMB), 1,4-bis (triphenylsilyl) benzene ( Hereinafter, it is described as UGH 2.), oxadiazole derivatives, triazole derivatives, fullerene derivatives, phenanthroline derivatives, quinoline derivatives and the like can be used.

<Electron injection layer>
The electron injection layer 9 improves the electron injection efficiency from the cathode to the electron transport layer 8. Specifically, lithium fluoride, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, magnesium oxide and aluminum oxide are desirable. Moreover, of course, it is not necessarily limited to these materials, and two or more of these materials may be used in combination.

<Board>
Examples of the substrate 10 include a glass substrate, a metal substrate, and a plastic substrate on which an inorganic material such as SiO ₂ , SiN x, Al ₂ O ₃ or the like is formed. Examples of metal substrate materials include alloys such as stainless steel and 42 alloy. Examples of plastic substrate materials include polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polysulfone, polycarbonate, polyimide and the like.

<Anode>
As the anode material, any material having a high work function can be used. Specific examples thereof include conductive oxides such as ITO and IZO, and metals having a large work function such as thin Ag. The pattern formation of the electrode can be generally performed using photolithography or the like on a substrate such as glass.

<Cathode>
The cathode material is an electrode for injecting electrons into the light emitting layer 3. Specifically, a laminate of LiF and Al, an Mg: Ag alloy, or the like is preferably used. Moreover, it is not limited to these materials, For example, a Cs compound, a Ba compound, a Ca compound etc. can be used instead of LiF.

<Coating liquid>
The coating solution is a solution of host and dopant in an appropriate solvent. The solvent to be used here may be, for example, an aromatic hydrocarbon solvent such as toluene and anisole, an ether solvent such as tetrahydrofuran, an alcohol, and a solvent such as a fluorocarbon solvent. In addition, a mixed solvent in which a plurality of the above-mentioned solvents are mixed may be used to adjust the solubility of each material and the drying rate.

Examples of coating methods for forming the light emitting layer 3 include spin coating method, casting method, dip coating method, spray coating method, screen printing method, ink jet printing method, reverse printing method, slot die coating method and the like. . The light emitting layer 3 is formed using one of these methods.

Hereinafter, the present invention will be described in detail by way of examples.

Example 1
FIG. 2 is a cross-sectional view of the organic white light emitting element of the first embodiment. The following materials were used for each layer.
For the substrate 10, a glass substrate was used, and for the lower electrode 11, a laminated film of Ag and ITO was used. PEDOT (poly (3,4-ethylenedioxythiophene)): PSS (polystyrene sulfonate) was used for the hole injection layer 1. For the hole transport layer 2, a triphenylamine-based polymer was used.

As a host of the light emitting layer 3, a carbazole derivative represented by the formula (3) was used.

Moreover, the Ir complex represented by Formula (4) was used for blue dopant.

The absorption peak wavelength of this blue dopant is 440 nm (2.82 eV) in a toluene solution, and the emission peak wavelength is 500 nm (2.48 eV).

Moreover, the Ir complex represented by Formula (5) was used for green dopant.

The absorption peak wavelength of this green dopant was 450 nm (2.75 eV) in a toluene solution, and the emission peak wavelength was 560 nm (2.21 eV).

Moreover, the Ir complex represented by Formula (6) was used for the red dopant.

The absorption peak wavelength of this red dopant was 460 nm (2.69 eV), and the emission peak wavelength was 590 nm (2.1 eV). The maximum difference of absorption peaks in this case is 0.13 eV, and the maximum difference of emission peaks is 0.38 eV.

The light emitting layer coating solution is obtained by dissolving a host material, a red dopant, a green dopant and a blue dopant in an appropriate solvent. In this example, the molar concentration of the host material, the red dopant, the green dopant and the blue dopant in the solid content is 0.5% for the red dopant, 1.0% for the green dopant, and 6% for the blue dopant. As a solvent, toluene was used.

For the electron transport layer 8, a layered structure of the compound represented by the formula (7) and the compound represented by the formula (8) was used.

MgAg was used for the electron injection layer 9. In addition, IZO was used for the upper electrode. When a positive potential was applied to the lower electrode of the present example and a negative potential was applied to the upper electrode, white light emission consisting of three colors of red, green and blue was obtained. The intensity ratio of the blue and red emission peaks was 1: 1.

FIG. 1 is a cross-sectional view of an apparatus of a light source using the organic white light emitting element of this example.

The above-mentioned organic light emitting element was bonded to the sealing layer 17 with the resin layer 16 using an epoxy resin and sealed. A scattering light extraction layer 18 was provided on the opposite side of the sealing substrate. When a positive potential was applied to the lower electrode and a negative potential to the upper electrode, a light source device emitting white light was obtained.

Comparative Example 1
A light emitting device was produced in the same manner as in Example 1 except that a compound represented by the following formula (9) as a green dopant and a compound represented by the following formula (10) were used as a red dopant: blue and green light emission Was weak, and almost red light emission was obtained. The intensity ratio of the blue and red emission peaks was 1: 3.

The absorption peak wavelength of this green dopant was 470 nm (2.64 eV), and the peak of the emission spectrum was 530 nm (2.34 eV). The absorption peak wavelength of this red dopant was 480 nm (2.58 eV), and the peak of the emission spectrum was 620 nm (2.00 eV).

As described above, in the case of the present comparative example, the maximum difference between the absorption peaks of the respective light emitting dopants is as large as 0.24 eV, so that the light emission peak of the blue dopant and the absorption peak of the green dopant and the red dopant are closer to those of Example 1. Because of this, energy transfer from the blue dopant is likely to occur, resulting in almost red light emission.

(Example 2)
An organic light-emitting device was produced in the same manner as in Example 1 except that the compound represented by Formula (11) was used as a red dopant. As a result, white light emission consisting of three colors of red, green and blue was obtained.

In addition, the concentration distribution of the dopant in the light emitting layer was measured using oblique cutting TOF-SIMS, and it was confirmed that the red dopant was located in the vicinity of the interface on the electron transport layer side of the light emitting layer.

(Example 3)
An organic light-emitting device was produced in the same manner as in Example 1 except that the compound represented by Formula (12) was used as the red dopant, and the compound represented by Formula (13) was used as the hole transport layer 2. As a result, white light emission consisting of three colors of red, green and blue was obtained. The intensity ratio of the blue and red emission peaks was 1: 1.

In addition, the concentration distribution of the dopant in the light emitting layer is measured using oblique cutting TOF-SIMS, and the concentration of the red dopant at the interface portion on the hole transport layer side of the light emitting layer is 5 compared to the central portion of the light emitting layer. It confirmed that it was more than double. For this reason, since blue and green dopants and red dopants in close proximity to each other are less than usual, sufficiently strong blue luminescence can be obtained.

Reference Signs List 1 hole injection layer 2 hole transport layer 3 light emitting layer 4 host 5 red dopant 6 green dopant 7 blue dopant 8 electron transport layer 9 electron injection layer DESCRIPTION OF REFERENCE NUMERALS 10 substrate 11 lower electrode 12 upper electrode 13 organic layer 14 bank 15 reverse taper bank 16 resin layer 17 sealing substrate 18 light extraction layer 20 drive circuit

Claims (14)

A first electrode,
A second electrode,
An organic light emitting device having a light emitting layer disposed between the first electrode and the second electrode,
The first electrode, the light emitting layer, and the second electrode are formed in this order on a substrate,
The light emitting layer comprises a host and a plurality of dopants,
An organic light emitting device characterized in that absorption peaks of a plurality of dopants are at substantially the same position, and light emission peaks are at different positions. The light emitting dopant has three types, and has a dopant having a wavelength difference between an emission peak and an absorption peak different from the wavelength difference between the emission peak and the absorption peak of the light emitting dopant emitting light at the shortest wavelength. The organic light emitting element as described. The first light emitting dopant in the light emitting layer has a concentration gradient in the light emitting layer, the highest concentration portion is present on the light emitting layer surface side, and the other two dopants emit light with almost the same absorption peak position The organic light emitting element according to claim 1 or 2, wherein peak positions are different. The organic light emitting device according to claim 1 or 2, wherein the light emitting dopant in the light emitting layer is represented by the following general formula (1).

In the general formula (1), Ar1 and Ar2 each represent an aromatic hydrocarbon or an aromatic heterocyclic ring.
Ar1 and Ar2 each have a hydrogen atom or a substituent represented by the following general formula (2). M represents an element of Groups 8, 9 or 10 in the periodic table. m and n each represent an integer of 1 to 3;
L represents an optionally substituted ligand. L represents a ligand, which may be substituted by the following substituent, and the substituent is a hydrogen atom, an alkyl group having 4 to 15 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 5 carbon atoms 5, an acyl group, a fluoroalkyl group having 3 to 6 carbon atoms, the following general formula

It is any of the substituents represented by (2).
In the general formula (2), R 1 represents a hydrogen atom or a substituent, and the substituent is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an acyl having 1 to 5 carbon atoms A fluoroalkyl group having 1 to 6 carbon atoms. A first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode, and on the substrate, the first electrode, the light emitting layer, An organic light emitting element which is formed in the order of the second electrode, the light emitting layer contains a host and a plurality of dopants, absorption peaks of the plurality of dopants are approximately at the same position, and emission peaks are at different positions;
And a driving circuit for driving the organic light emitting element. The light emitting dopant has three types, and has a dopant having a wavelength difference between an emission peak and an absorption peak different from the wavelength difference between the emission peak and the absorption peak of the light emitting dopant emitting light at the shortest wavelength. The light source device as described. The first light emitting dopant in the light emitting layer has a concentration gradient in the light emitting layer, the highest concentration portion is present on the light emitting layer surface side, and the other two dopants emit light with almost the same absorption peak position The light source device according to claim 5 or 6, wherein peak positions are different. The light emitting device according to claim 5, wherein the light emitting dopant in the light emitting layer is expressed by the following general formula (1).

In the general formula (1), Ar1 and Ar2 each represent an aromatic hydrocarbon or an aromatic heterocyclic ring.
Ar1 and Ar2 each have a hydrogen atom or a substituent represented by the following general formula (2). M represents an element of Groups 8, 9 or 10 in the periodic table. m and n each represent an integer of 1 to 3;
L represents an optionally substituted ligand. L represents a ligand, which may be substituted by the following substituent, and the substituent is a hydrogen atom, an alkyl group having 4 to 15 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 5 carbon atoms 5, an acyl group, a fluoroalkyl group having 3 to 6 carbon atoms, the following general formula

It is any of the substituents represented by (2).
In the general formula (2), R 1 represents a hydrogen atom or a substituent, and the substituent is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an acyl having 1 to 5 carbon atoms A group, which is a fluoroalkyl group having 1 to 6 carbon atoms. A coating solution for forming a light emitting layer, comprising an organic solvent, a host substance, and a plurality of dopants,
A coating liquid for forming an organic light emitting layer, wherein absorption peaks of the plurality of dopants are at substantially the same position, and light emission peaks are at different positions. The coating liquid for forming an organic light emitting layer according to claim 9, wherein the coating liquid for forming an organic light emitting layer contains a binder. The light emitting dopant in the said light emitting layer is represented by following General formula (1), The coating liquid for organic light emitting layer formation of Claim 9 or 10 characterized by the above-mentioned.

In the general formula (1), Ar1 and Ar2 each represent an aromatic hydrocarbon or an aromatic heterocyclic ring.
Ar1 and Ar2 each have a hydrogen atom or a substituent represented by the following general formula (2). M represents an element of Groups 8, 9 or 10 in the periodic table. m and n each represent an integer of 1 to 3;
L represents an optionally substituted ligand. L represents a ligand, which may be substituted by the following substituent, and the substituent is a hydrogen atom, an alkyl group having 4 to 15 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 5 carbon atoms 5, an acyl group, a fluoroalkyl group having 3 to 6 carbon atoms, the following general formula (2)

Or any of the substituents represented by
In the general formula (2), R 1 represents a hydrogen atom or a substituent, and the substituent is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an acyl having 1 to 5 carbon atoms A fluoroalkyl group having 1 to 6 carbon atoms. An organic light emitting layer material comprising a host and a plurality of dopants,
An organic light emitting layer material, wherein absorption peaks of the plurality of dopants are at substantially the same position, and light emission peaks are at different positions. The total of 0.0005 to 5% by mass of the plurality of dopants and 0 to 50% by mass of the binder based on the mass of the host, the absorption peaks of the plurality of dopants are at substantially the same position, and the emission peaks are different from each other The organic light emitting layer material according to claim 12, characterized in that it is in position. The organic light emitting layer material according to claim 12, wherein the light emitting dopant in the light emitting layer is represented by the following general formula (1).

In the general formula (1), Ar1 and Ar2 each represent an aromatic hydrocarbon or an aromatic heterocyclic ring.
Ar1 and Ar2 each have a hydrogen atom or a substituent represented by the following general formula (2). M represents an element of Groups 8, 9 or 10 in the periodic table. m and n each represent an integer of 1 to 3;
L represents an optionally substituted ligand. L represents a ligand, which may be substituted by the following substituent, and the substituent is a hydrogen atom, an alkyl group having 4 to 15 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 to 5 carbon atoms 5, an acyl group, a fluoroalkyl group having 3 to 6 carbon atoms, the following general formula (2)

Or any of the substituents represented by
In the general formula (2), R 1 represents a hydrogen atom or a substituent, and the substituent is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an acyl having 1 to 5 carbon atoms A fluoroalkyl group having 1 to 6 carbon atoms.

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