JP5643723B2 - Organic light emitting device, light source device, organic light emitting layer forming coating liquid and organic light emitting layer material - Google Patents

Description

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

  As an organic white light emitting device having a single light emitting layer, an organic white light emitting layer composed of a composition containing at least (a) a polymer and (b) an emission center forming compound is inserted between electrodes. An EL device, in which the composition contains an electron transporting material and a hole transporting material in a well-balanced manner, and the polymer has an emission color of blue or a shorter wavelength than that of the polymer. The luminescent center forming compound is present in a state where two or more of the luminescent center forming compounds are molecularly dispersed in the polymer, and each luminescent center forming compound emits light alone, and the colored light as the whole organic EL element is Patent Document 1 reports a single-layer white light-emitting organic EL device that uses a combination of two or more of the luminescent center-forming compounds so that white light can be seen. 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, wherein any of the organic layers has a branched alkyl group. An organic electroluminescence device characterized by comprising an organic electroluminescence device comprising a metal complex having a group is disclosed.

  In patent document 3, the host material for organic EL elements containing an iridium complex is disclosed.

  In Patent Document 4, b (b is an integer of 1 to (a + 2)) -NR1R2 on a basic skeleton in which a (6 is an integer of 3 or more) aromatic 6-membered rings are m-linked. An organic group having a group (R 1 and R 2 are each independently an arbitrary substituent), and each of the —NR 1 R 2 groups is bonded to the m-position with respect to the m-linked site in the aromatic 6-membered ring. Compound (However, the aromatic 6-membered ring may have a substituent other than the —NR 1 R 2 group, and the plurality of aromatic 6-membered rings contained in one molecule may be the same or different rings. In addition, a plurality of —NR 1 R 2 groups contained in one molecule may be the same group or different groups.

Japanese Patent Laid-Open No. 09-063770 JP 2010-185068 A JP 2006-290988 A Japanese Patent Laid-Open No. 2005-68068

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

  An object of the present invention is to provide an organic light emitting layer material in which the dopant concentration can be easily controlled, an organic light emitting layer forming coating solution using the organic light emitting layer material, an organic light emitting device using the organic light emitting layer forming coating solution, and It is providing the light source device using an organic light emitting element.

In order to solve the above problems, the present invention is an organic light emitting device having 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, and the second electrode are formed in this order. The light emitting layer includes a host and a plurality of dopants, and absorption peaks of the plurality of dopants are at substantially the same position, and light emission The present invention provides an organic light emitting device characterized in that peaks are at different positions. That is, when 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 has a wavelength of blue, red, or green. By selecting materials that are at an energy level, energy transfer from a dopant with a high energy level (eg, blue) to a low energy level (eg, green) is suppressed, and, for example, the blue emission peak is prevented from being lowered. Can do. Therefore, a remarkable effect is obtained that the initial emission intensity of each dopant can be obtained without finely controlling the blending amount of the dopant.

  In the present invention, by appropriately selecting the absorption peak and emission peak of a plurality of dopants added to the host (relation between the absorption wavelength and the emission wavelength), the dopant having absorbed energy (for example, emitting blue light). The dopant does not transfer energy to another dopant (for example, a dopant that emits red light), and the emission peak of the specific dopant is not weakened. Therefore, unlike the prior art, it is not necessary to adjust the concentration of the dopants so that the emission intensity of each dopant becomes a sufficient value in consideration of the above-described energy transfer.

  INDUSTRIAL APPLICABILITY According to the present invention, an organic light emitting layer material capable of easily controlling the dopant concentration and realizing white light emission with a high color temperature (high blue light emission peak intensity), and an organic light emitting layer forming coating solution using the organic light emitting layer material An organic light emitting device using a coating solution for forming an organic light emitting layer and a light source device using the organic light emitting device can be provided.

It is light source device sectional drawing in one embodiment of this 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 clarified by the following description of embodiments.

  It is as follows when the main thing of embodiment by this invention is enumerated.

(1) An organic light emitting device having a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode,
On the substrate, the first electrode, the light emitting layer, and the second electrode are formed in this order. 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. An organic light emitting device comprising a dopant having a wavelength difference between an emission peak and an absorption peak different from a wavelength difference between an emission peak and an absorption peak of the emission dopant.

  The phrase “absorption peaks at substantially the same position” as used herein means that the maximum difference between the absorption peaks of the respective dopants is within 0.2 eV. In addition, the fact 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 having a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode,
On the substrate, the first electrode, the light emitting layer, and the second electrode are formed in this order. 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, wherein the highest concentration portion is present on the light emitting layer surface side, and the other two dopants have substantially the same absorption peak position but different emission peak positions.

(3) An organic light emitting device having a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode,
On the substrate, the first electrode, the light emitting layer, and the second electrode are formed in this order. 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, wherein the highest concentration portion is present on the light emitting layer surface side, and the other two dopants have substantially the same absorption peak position but different emission peak positions.

(4) An organic light emitting device having a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode,
On the substrate, the first electrode, the light emitting layer, and the second electrode are formed in this order. 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). An organic light-emitting device is shown.

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

  L represents a ligand and may be substituted with the following substituents, and the substituents are a hydrogen atom, an alkyl group having 4 to 15 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and 1 to 5 carbon atoms. An acyl group, a C3-C6 fluoroalkyl group, or a substituent represented by the following general formula (2).

  In General Formula (2), R1 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, or an acyl having 1 to 5 carbon atoms. Group, and a fluoroalkyl group having 1 to 6 carbon atoms.

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

  (6) On the basis of the mass of the host, each of the plurality of dopants includes 0.05 to 50% by mass and the binder includes 0 to 50% by mass. The absorption peaks of the plurality of dopants are at substantially the same position, and the emission peak is An organic light emitting layer material characterized by being in different positions.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various modifications by those skilled in the art are within the scope of the technical idea disclosed in this specification. Changes and modifications are possible. In all the drawings for explaining the present invention, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

  In an organic light emitting device manufactured by a conventional coating method, the green dopant concentration is 0.02 mol%, the red dopant concentration is 0.02 mol%, and 0.015 mol% in order to suppress energy transfer from the blue dopant. The dopant concentration is difficult to control. In addition, sufficient light emission efficiency cannot be obtained due to energy transfer between the 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 unit includes a substrate 10, a lower electrode 11, an upper electrode 12, an organic layer 13, a bank 14, a reverse taper bank 15, a resin layer 16, a transparent sealing substrate 17, and a 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. In addition to the glass substrate, a plastic substrate or a metal substrate provided with an appropriate 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. In addition to the laminate, Mo, Cr, a combination of a transparent electrode and a light diffusion layer, or the like can also be used. Further, the lower electrode 11 is not limited to the anode, but can also be used 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 is used by patterning on the substrate 10 by photolithography.

  An upper electrode 12 is formed on the organic layer 13. The upper electrode 12 is a cathode. A laminate of transparent electrodes such as ITO and IZO and electron injecting electrodes such as MgAg and Li is used. In addition to the laminate, MgAg or an Ag thin film can be used alone. Further, when ITO or IZO is formed 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. A metal oxide such as molybdenum oxide or vanadium oxide is used for the buffer layer. As described above, when the lower electrode 11 is a cathode, 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 the specific light emitting unit is connected to the lower electrode 11 of the light emitting unit adjacent to the specific light emitting unit. Thereby, a some light emission part can be connected in series. A light source device is formed by connecting a driving 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 have a single layer structure including 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. Photosensitive polyimide is preferable as the material of the bank 14. However, it is not limited to photosensitive polyimide, and an acrylic resin or the like can also be used. Non-photosensitive materials can also be used.

  The reverse taper bank 15 is used to prevent the upper electrode 12 of the adjacent light emitting part 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 to form.

  A resin layer 16 is formed on the upper electrode 12. The resin layer 16 is used for sealing the light emitting part. Various polymers such as an epoxy resin can be used. In order to improve the sealing performance, an inorganic passivation film may be used between the upper electrode 12 and the resin layer 16.

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

  A light extraction layer 18 is formed on the sealing substrate 17. The light extraction layer 18 is used for efficiently extracting light emitted from the light emitting layer in the organic layer 13. As the light extraction layer 18, a film having scattering properties and diffuse reflection properties is used. The organic light emitting layer 13 is excited by the drive circuit 20 having a wiring connecting the power source and the lower electrode 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. This 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 either the first electrode or 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 element of FIG. 2 is a bottom emission type that takes out light emitted from the light emitting layer 3 from the lower electrode 11 side. It is. The lower electrode 11 is a transparent electrode serving as an anode, and the upper electrode 12 is a reflective electrode serving as 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 have a single layer structure including 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 between the layers.

  The light emitting layer 3 contains a host and a dopant. The light emitting layer 3 is a layer that emits light by recombination of electrons and holes injected from the upper electrode 12, the lower electrode 11, the electron transport layer 8, or the hole transport layer 2. 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 the dopant, a fluorescent compound or a phosphorescent compound can be used. The dopant includes one or more of a red dopant, a green dopant, and a blue dopant. The material for forming the light emitting layer 3 includes a host, a red dopant, a green dopant, and a blue dopant. In the case where white light is emitted from the light emitting layer 3, the material for forming the light emitting layer 3 includes a host, a material containing a red dopant and a blue dopant, a host, a material containing a red dopant and a green dopant, a host, a green dopant and a blue color. It may be one containing a dopant. When light other than white light is emitted from the light emitting layer 3, the material for forming the light emitting layer 3 may include, for example, a host and a monochromatic dopant.

  The emission color of the red dopant, the emission color of the green dopant, and the emission color of the blue dopant are different. “Different emission colors” means that the wavelengths indicating the maximum intensities in the PL spectra of the respective dopants are different.

  The light emitting layer 3 may contain a binder polymer. Examples of the binder polymer include one or more of polycarbonate, polystyrene, acrylic resin, polyamide, and gelatin. By containing the binder polymer, the viscosity of the light emitting layer 3 can be increased, and the printability can be improved. Moreover, the stability of the film of the light emitting layer 3 can be improved. 0-100 mass% is good with respect to a host, and 1-50 mass% is preferable with respect to a host. Based on the mass of the solvent, the host is 0.1 to 10% by mass, preferably 0.5 to 5% by mass, and the dopant is 0.05 to 5% by mass, preferably 0.075 to 2.5% by mass. . However, in the case of the photosensitive layer material excluding the solvent, 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 that emits light after an excited state is formed by an electric field, and generally has a wider difference (band gap) between HOMO and LUMO than a dopant. As the host, it is preferable to use a carbazole derivative, a fluorene derivative, an arylsilane derivative, or the like. In order to obtain efficient light emission, it is preferable that the excitation energy of the host is sufficiently larger than the excitation energy of the blue dopant. The excitation energy is measured using an emission spectrum.

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

  When light emitting layer 3 has a blue dopant and a dopant (green dopant, red dopant) whose wavelength indicating the maximum intensity of the PL spectrum is longer than that of the blue dopant, and the green dopant or the red dopant is a surface dopant, excitation from the blue dopant Since energy transfer to a low-energy green dopant or red dopant is suppressed, the molar concentration of the blue dopant in the light-emitting layer 3 in the solid content is higher than the molar concentration in the solid content of the green dopant or the red dopant in the light-emitting layer 3. Can be big. Here, the surface dopant is a dopant that 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 PL spectrum intensity at room temperature between 500 nm and 590 nm. An Ir complex is used as the green dopant. In addition, 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 the light emitting layer 3 has a green dopant and a dopant (red dopant) whose wavelength indicating the maximum intensity of the PL spectrum is longer than that of the green dopant, and the red dopant is a surface dopant, the green dopant is changed to a red dopant having a low excitation energy. Therefore, the molar concentration of the green dopant in the solid content of the light emitting layer 3 can be made higher 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 PL spectrum intensity at room temperature between 590 nm and 780 nm. An Ir complex is used as the red dopant. In addition, various metal complexes such as Pd, Pt, Al and 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 luminous efficiency and lifetime. Moreover, although it is not essential, it is used for the purpose of relaxing the unevenness of the anode. The hole injection layer 1 may be provided as 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). In addition, polypyrrole-based or triphenylamine-based polymer materials can be used. Further, phthalocyanine compounds and starburst amine compounds that are often used in combination with a low molecular weight (weight average molecular weight 10,000 or less) material system are also applicable.

<Hole transport layer>
The hole transport layer 2 is used for transporting holes injected from the anode to the light emitting layer. As the hole transport layer 2, a homopolymer or a copolymer of fluorene, carbazole, arylamine or the like is used. As the copolymer, a material having a thiophene-based or pyrrole-based skeleton can also be used. A polymer having a skeleton such as fluorene, carbazole, arylamine, thiophene, or pyrrole in the side chain can also be used. Further, 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 also 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. In a broad sense, the electron injection layer 9 and the hole blocking layer are also included in the electron transport layer 8. The electron transport layer 8 may be provided as a single layer or a plurality of layers. Examples of the material for the electron transport layer 8 include bis (2-methyl-8-quinolinolato) -4- (phenylphenolato) aluminum (hereinafter referred to as BAlq), tris (8-quinolinolato) aluminum (hereinafter referred to as Alq3), Tris (2,4,6-trimethyl-3- (pyridin-3-yl) phenyl) borane (hereinafter, 3TPYMB), 1,4-Bis (triphenylsilyl) benzene (hereinafter, UGH2), oxadiazole derivative, triazole derivative , Fullerene derivatives, phenanthroline derivatives, quinoline derivatives, and the like can be used.

<Electron injection layer>
The electron injection layer 9 improves the efficiency of electron injection 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. Of course, the material is not 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, a plastic substrate on which an inorganic material such as SiO ₂ , SiNx, and Al ₂ O ₃ is formed. Examples of the metal substrate material include alloys such as stainless steel and 42 alloy. Examples of the plastic substrate material include polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polysulfone, polycarbonate, and polyimide.

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

<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, Ba compound, Ca compound etc. can be used instead of LiF.

<Coating liquid>
The coating solution is obtained by dissolving a host and a dopant in an appropriate solvent. The solvent used here may be any solvent in which each material can be dissolved, for example, an aromatic hydrocarbon solvent such as toluene or anisole, an ether solvent such as tetrahydrofuran, an alcohol, or a fluorine solvent. Further, a mixed solvent in which a plurality of the above-mentioned solvents are mixed for adjusting the solubility of each material and the drying speed may be used.

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

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

  A carbazole derivative represented by the formula (3) was used as the host of the light emitting layer 3.

  As the blue dopant, an Ir complex represented by the formula (4) was used.

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

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

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

  As the red dopant, an Ir complex represented by the formula (6) was used.

  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). In this case, the maximum difference in absorption peak is 0.13 eV, and the maximum difference in emission peak 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 concentrations of the host material, the red dopant, the green dopant, and the blue dopant in the solid content are 0.5% for the red dopant, 1.0% for the green dopant, and 6% for the blue dopant. Toluene was used as the solvent.

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

  MgAg was used for the electron injection layer 9. Moreover, IZO was used for the upper electrode. When a positive potential was applied to the lower electrode of this 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 a light source device using the organic white light emitting device of this example.

  The organic light-emitting element was bonded to the sealing substrate 17 using an epoxy resin for the resin layer 16 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 was applied 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) was used as the green dopant and a compound represented by the following formula (10) was used as the red dopant. 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).

  Thus, in the case of this comparative example, the maximum difference of the absorption peak of each light emission dopant is as large as 0.24 eV, Therefore, the light emission peak of a blue dopant and the absorption peak of a green dopant and a red dopant are nearer than Example 1. For this reason, energy transfer from the blue dopant is likely to occur, resulting in almost red light emission.

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

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

  An organic light emitting device was produced in the same manner as in Example 1 except that the compound represented by the formula (12) was used as the red dopant and the compound represented by the 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.

  Further, the concentration distribution of the dopant in the light emitting layer was measured using oblique cutting TOF-SIMS, and the concentration of the red dopant in the interface portion on the hole transport layer side of the light emitting layer was 5 as compared with the central portion of the light emitting layer. It was confirmed that it was more than double. For this reason, since blue dopant and the red dopant which adjoins a green dopant are fewer than usual, sufficiently strong blue light emission is obtained.

DESCRIPTION OF SYMBOLS 1 ... Hole injection layer, 2 ... Hole transport layer, 3 ... Light emitting layer , 8 ... Electron transport layer, 9 ... Electron injection layer, 10 ... Substrate, 11 ... Lower electrode, 12 ... Upper electrode, 13 ... Organic layer, DESCRIPTION OF SYMBOLS 14 ... Bank, 15 ... Reverse taper bank, 16 ... Resin layer, 17 ... Sealing substrate, 18 ... Light extraction layer, 20 ... Drive circuit .

Claims (12)

An organic light emitting device having a first light emitting layer disposed between a first electrode, a second electrode, and the first electrode and the second electrode,
On the substrate, the first electrode, the one light emitting layer, the second electrode are formed in this order,
The light emitting layer is only one and includes a host and a plurality of light emitting dopants,
The plurality of light-emitting dopants include red, green, and blue light-emitting dopants,
An energy difference between absorption peaks of the plurality of light-emitting dopants is within 0.2 eV,
An organic light emission characterized in that an energy difference between an emission peak and an absorption peak of a light emitting dopant that emits light at the shortest wavelength among the plurality of light emitting dopants is different from an energy difference between an emission peak and an absorption peak of another light emitting dopant. element.   The first light-emitting dopant in the light-emitting layer has a concentration gradient in the light-emitting layer, the highest concentration portion exists on the surface side of the light-emitting layer, and the other two dopants have an absorption peak energy difference of 0. The organic light emitting device according to claim 1, wherein the organic light emitting device is within 2 eV and has different emission peak positions. The organic light-emitting device according to claim 1, wherein the light-emitting dopant in the light-emitting layer is represented by the following general formula (1).

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

In General Formula (2), R1 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, or an acyl having 1 to 5 carbon atoms. Group, and a fluoroalkyl group having 1 to 6 carbon atoms. A first light emitting layer disposed between the first electrode, the second electrode, and the first electrode and the second electrode;
On the substrate, the first electrode, the one light emitting layer, and the second electrode are formed in this order, the light emitting layer is only one, includes a host and a plurality of light emitting dopants,
The plurality of light-emitting dopants include red, green, and blue light-emitting dopants,
An energy difference between absorption peaks of the plurality of light-emitting dopants is within 0.2 eV,
Among the plurality of light emitting dopants, an organic light emitting device in which an energy difference between an emission peak and an absorption peak of a light emitting dopant that emits light at the shortest wavelength and an energy difference between an emission peak and an absorption peak of another light emitting dopant is different, and the organic A light source device comprising a drive circuit for driving a light emitting element.   The first light-emitting dopant in the light-emitting layer has a concentration gradient in the light-emitting layer, the highest concentration portion exists on the surface side of the light-emitting layer, and the other two dopants have an absorption peak energy difference of 0. The light source device according to claim 4, wherein the light source device is within 2 eV and has different emission peak positions. The light-emitting device according to claim 4 or 5, wherein the light-emitting dopant in the light-emitting layer is represented by the following general formula (1).

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

In General Formula (2), R1 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, or an acyl having 1 to 5 carbon atoms. Group, and a fluoroalkyl group having 1 to 6 carbon atoms. And an organic solvent, including a host material, a plurality of kinds of light emitting dopants, and a coating liquid for forming a single light emitting layer,
The plurality of light-emitting dopants include red, green, and blue light-emitting dopants,
The energy difference between the absorption peaks of the plurality of light emitting dopants is within 0.2 eV, and among the light emitting dopants, the energy difference between the light emission peak and the absorption peak of the light emitting dopant that emits light at the shortest wavelength, and other light emitting dopants A coating liquid for forming an organic light emitting layer, wherein the difference in energy between the emission peak and the absorption peak is different.   The said organic light emitting layer forming coating liquid contains the binder, The organic light emitting layer forming coating liquid of Claim 7 characterized by the above-mentioned. The luminescent 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 7 characterized by the above-mentioned.

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

In General Formula (2), R1 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, or an acyl having 1 to 5 carbon atoms. Group, and a fluoroalkyl group having 1 to 6 carbon atoms. Comprising a host, a plurality of light-emitting dopants, and an organic light-emitting layer material to form a single light emitting layer,
The plurality of light-emitting dopants include red, green, and blue light-emitting dopants,
An energy difference between absorption peaks of the plurality of light-emitting dopants is within 0.2 eV,
An organic light emission characterized in that an energy difference between an emission peak and an absorption peak of a light emitting dopant that emits light at the shortest wavelength among the plurality of light emitting dopants is different from an energy difference between an emission peak and an absorption peak of another light emitting dopant. Layer material. Wherein based on the weight of the host, the organic light-emitting layer material as claimed 0-50 wt% of 0.0005% by weight and the binder a plurality of dopants in total to claim 10, characterized in including it. The organic light emitting layer material according to claim 10, wherein the light emitting dopant in the light emitting layer is represented by the following general formula (1).

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

In General Formula (2), R1 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, or an acyl having 1 to 5 carbon atoms. Or a C 1-6 fluoroalkyl group.

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