JP2008198387A - Organic EL device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a white light-emitting organic EL (electroluminescence) element used for a backlight of a color liquid crystal display, other illuminators, displays, and the like.

  In recent years, a color conversion (CCM) method has been studied as an example of a multicolor or full color display method using an organic EL element. This system absorbs near-ultraviolet light, blue light, blue-green light, or white light emitted from an organic EL element, and performs color distribution conversion to include a color conversion dye that emits light in the visible light range. Is provided. When the color conversion method is used, since the light emission color of the light source is not limited to white, it is possible to increase the degree of freedom in selecting the light source. For example, green and red light can be obtained by wavelength distribution conversion using an organic EL element that emits blue to blue-green light.

Recently, as a color conversion method, in addition to a method using a color conversion layer provided on a substrate independent of an organic EL element, an organic EL element having a component layer provided with a color conversion function has been proposed. (See Patent Documents 1 to 3).
JP-A-6-215874 JP-A-6-203963 JP 2001-279238 A International Publication No. 00/18193 Pamphlet Japanese Patent Application Laid-Open No. 2002-231452 JP 2002-033193 A JP 2002-313582 A International Publication No. 2005/055672 Pamphlet JP 2002-305087 A International Publication No. 2006/001194 Pamphlet JP-A-9-228160

  When the component layer of the organic EL element has a color conversion function, the component layer is generally doped with a color conversion dye. However, since color conversion dyes are generally insulative, increasing the doping amount of the color conversion dye to achieve the desired wavelength distribution hinders the movement of carriers (electrons or holes) in the constituent layers. As a result, the drive voltage increases. In order to prevent this decrease in carrier transport characteristics, measures such as a reduction in the amount of the color conversion dye dope or a reduction in the thickness of the constituent layers can be considered. There is a possibility that light from the light emitting layer may pass through the constituent layer.

  An organic EL element is known in which a film in which a fluorescent dye for color conversion is mixed in a transparent conductive material is applied and formed between an anode and a light emitting layer (see Patent Documents 4 to 5). These elements require a film thickness of several μm to obtain a desired color conversion efficiency, and are not practical for realizing a thin-film organic EL element. It is important that the formation method of the constituent layers of the organic EL element is not a coating method but a dry process such as vapor deposition.

An object of the present invention is an organic EL element including an organic EL layer sandwiched between a pair of electrodes, and having at least an organic light emitting layer and a color conversion layer in the organic EL layer, and achieves a desired wavelength distribution It is to provide an organic EL device having a thin color conversion layer having a sufficient color conversion capability and at the same time having a high carrier transport property.
It is known that carbon nanotubes having high electronic properties are applied to organic EL elements. For example, (1) carbon nanotubes are doped in the organic layer or the electron injection layer or hole injection layer of the organic light emitting device to increase the carrier mobility of the organic layer (Patent Document 6), and (2) the carbon nanotubes absorb light. (Patent Document 7), (3) Carbon nanotubes are mixed in the organic light emitting layer (Patent Document 8), (4) The tube surface of the electron injection layer (5) A conductive phase containing carbon nanotubes is provided inside the phosphor in an inorganic EL phosphor (Patent Document 10). Are known.

  In the examples of (1), (2) and (3) above, it is shown that the organic material and the carbon nanomaterial are mixed in a solution, applied and dried to form the layer, and the conductivity is improved. Yes. Moreover, in the example of (5), the powder obtained by mixing the sulfide which has ZnS activated by Ag or Cu as a main component and the carbon nanotube in a solution and drying it is fired. Furthermore, in the example of (4), it is shown that carbon nanotubes are formed vertically on the electron transport layer by the CVD method.

  However, in an organic EL device formed by a vapor deposition method, it has a function of color conversion that absorbs light emitted from the organic light emitting layer and converts it into light of a different wavelength, and is a continuum formed as a conductive path in the carrier transport direction. There is no suggestion of an example having a constituent layer in which a linear conductor having a structure is dispersed.

  The organic EL device of the present invention is an organic EL device comprising an organic EL layer sandwiched between a first electrode and a second electrode, wherein the organic EL layer comprises at least a carrier recombination layer and a carrier non-bonding layer. Is included. The carrier recombination layer emits electroluminescence light (hereinafter referred to as “EL light”) by recombination of electrons and holes injected from the first electrode and the second electrode, respectively. That is, it is an organic light emitting layer. The carrier non-bonding layer includes a light conversion material portion and a linear conductor. The light conversion material portion includes one or more color conversion dyes that absorb the EL light and emit photoluminescence light (hereinafter referred to as “PL light”) having lower energy than the light. The linear conductor is dispersed in the non-bonded layer and formed in the carrier transport direction of the non-bonded layer, and has a nanoscale size. That is, the carrier non-bonding layer is a constituent layer of the organic EL element and plays a role as a color conversion layer.

  Even if the content of the color conversion dye is increased by arranging a linear conductor extending from one electrode toward the carrier recombination layer in the carrier transport direction in the carrier non-bonding layer, As a whole, sufficient carrier transport capability can be provided. The linear conductor efficiently transports carriers injected from one electrode. As a result, a thin carrier non-bonding layer that realizes highly efficient color conversion can be formed as the color conversion layer, and the driving voltage of the organic EL element can be reduced.

In the present invention, the term “dispersed” means that the linear conductors are scattered and arranged, and includes not only the case where they are randomly arranged but also the case where they are regularly arranged. .
Here, the linear conductor is preferably a carbon nanotube. Carbon nanotubes have a sufficient carrier transport capability and are useful for lowering the driving voltage of organic EL elements.
Further, it is desirable that the linear conductor has a diameter of 5 nm to 30 nm and is dispersed on the surface of the first electrode at a density of 40 to 2000 / μm ² . By forming the linear conductor with such a diameter and density, the carrier non-bonding layer has sufficient carrier transport ability and light transmittance. In addition, by forming the linear conductor in this way, the light absorption of the linear conductor can be suppressed, and the color conversion function with the pigment can be secured.

The EL light may be blue or blue-green light having a peak wavelength at 400 nm to 500 nm.
The light conversion material part may further include a host material that absorbs the EL light. By dispersing the color conversion dye in the host material, it is possible to suppress a decrease in color conversion efficiency due to concentration quenching.

  Further, the carrier non-bonding layer is formed between the first electrode and the carrier recombination layer. The linear conductor is formed on a catalyst formed on the surface of the first electrode, and is mainly responsible for carrier transport in the carrier non-bonding layer. According to this configuration, the carrier non-bonding layer is inside the organic EL element, and the EL light emitted from the carrier recombination layer is incident on the carrier non-bonding layer with almost no attenuation. Therefore, it is possible to convert EL light into PL light more efficiently and obtain light of a desired hue (for example, white light). Further, since the linear conductor is in electrical contact with the first electrode via the catalyst, the carriers injected from the electrode can be efficiently transported to the carrier recombination layer. Further, since the linear conductor is formed on the catalyst, a light transmissive electrode can be employed as the first electrode serving as the base.

The main component of the catalyst is preferably Co or Ni. When such a metal catalyst is used, carbon nanotubes standing upright on the base can be selectively formed.
The method for producing an organic EL device of the present invention is characterized by a carrier non-bonding layer forming step. The carrier non-bonding layer is vapor deposited around each of the following steps, a step of forming a linear conductor on the first electrode, and a light conversion material portion containing one or more color conversion dyes. It is formed by the process to do.

  According to this manufacturing method, a linear conductor having a desired surface density can be formed on the first electrode. In addition, if the linear conductor is formed so as to be substantially perpendicular to the surface of the first electrode, an effect that the linear conductor is difficult to prevent the propagation of light can be obtained. Furthermore, a linear conductor can be formed with good reproducibility by forming a catalyst having a desired size and surface density on the first electrode. Moreover, since the light conversion material part is formed by vapor deposition, an organic EL element can be manufactured by a dry process consistent with other layers of the organic EL layer, and deterioration of the organic EL layer can be prevented.

  By adopting the above configuration, the PL light-emitting carrier non-bonding layer has a conductive path made of a linear conductor that transports carriers (electrons or holes), and a light conversion material portion that performs color conversion of EL light. And function separation. Therefore, even if the amount of the PL emission color conversion dye added to the carrier non-bonding layer is increased, the carrier transport characteristics of the PL light-emitting carrier non-bonding layer as a whole are not adversely affected. It is possible to achieve both reduction in driving voltage.

  In addition, the organic EL device of the present invention has a PL light-emitting carrier non-bonding layer that performs color conversion by PL light emission inside the organic EL device, so that there is a problem with the external CCM system that forms a color conversion layer outside the device Can be solved. That is, EL light can be incident on the carrier non-bonding layer without being affected by total reflection at the transparent electrode interface. Therefore, it is possible to convert EL light into PL light more efficiently and obtain light of a desired hue (for example, white light).

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. This is an example, and the present invention is not limited to this example.
FIG. 1 is a schematic view showing an embodiment of the organic EL element of the present invention, which is a cross-sectional view including a linear conductor and viewed from the short side direction of the first electrode. The organic EL element 10 has a structure in which an organic EL layer 50 is held between a pair of first electrodes 30 and second electrodes 40 formed on a substrate 20. The first electrode has a stripe shape and is made of a plurality of transparent conductors arranged in parallel. FIG. 1 shows a cross section including one of the first electrodes as viewed from the short side direction. An organic EL layer 50 is laminated on the surface of the first electrode. The organic EL layer includes at least a carrier non-bonding layer 51 and a carrier recombination layer 53. The carrier non-bonding layer is laminated on the surface of the first electrode. The carrier non-bonding layer includes a metal catalyst 510 formed on the surface of the first electrode, a linear conductor 511 extending from the surface of the catalyst, and a light conversion material portion 512. In the example of FIG. 1, the carrier non-bonding layer has a function as a hole injection layer in addition to a color conversion function. On the carrier non-bonding layer, a hole transport layer 52, a carrier recombination layer 53, an electron transport layer 54, and an electron injection layer 55 are stacked in this order, and the second electrode 40 is further stacked. The carrier recombination layer has a function as an organic light emitting layer.

When part of the EL light emitted from the carrier recombination layer 53 passes through the carrier non-bonding layer 51, the light conversion material part 512 undergoes wavelength distribution conversion and is converted into PL light having lower energy than the EL light. This PL light is mixed with the EL light and emitted from the first electrode 30 side to the outside of the organic EL element.
FIG. 2 is a cross-sectional view of the main part showing an example of the PL light-emitting carrier non-bonding layer 51. The carrier non-bonding layer includes at least a light conversion material portion 512 and a nanoscale linear conductor 511. The linear conductor smoothly moves carriers from the first electrode 30 (FIG. 1) to the carrier recombination layer 53. The light conversion material part includes one or more color conversion dyes (not shown), and these dyes absorb EL light and convert it into PL light. In addition, the linear conductor is dispersed in the non-bonding layer and continuously extends in the carrier transport direction of the non-bonding layer indicated by an arrow in the figure, and carriers injected from the first electrode 30 are recombined with the carrier. Transport to the layer 53 side.

  The light conversion material part 512 absorbs a part of incident light (EL light from the carrier recombination layer) and emits converted light (PL light) having a different wavelength. The converted light and the non-absorbed part of the incident light that has not been absorbed by the dye pass through the first electrode 30 and are emitted as light having different wavelength distributions. Desirably, the light conversion material part absorbs a part of blue to blue-green EL light having a peak wavelength from 400 nm to 500 nm emitted from the carrier recombination layer, and converts it into green to red PL light. Green or red PL light is mixed with blue or blue-green EL light that is not absorbed by the light conversion material portion to give white light. The white light in the present invention includes not only light that uniformly includes a wavelength component in the visible region (400 nm to 700 nm) but also light that does not include the wavelength component uniformly but appears white to the naked eye.

  The light conversion material part 512 includes one or more kinds of color conversion dyes. The color conversion dye means a dye that absorbs incident light and emits light in different wavelength ranges. Preferably, it is a dye that converts and emits EL light from the carrier recombination layer 53 into lower-energy PL light, and more preferably absorbs blue to blue-green light and has a desired wavelength range (for example, It is a pigment that emits green to red light.

  It is desirable that at least one of the color conversion dyes used in the present invention has an absorption maximum in a wavelength region of 470 nm to 580 nm and can emit red light having a wavelength of 580 nm or more. Such color conversion dyes include DCM-1 (I), DCM-2 (II), DCJTB (III), 4,4-difluoro-1,3,5,7-tetraphenyl-4-bora-3a, 4a-Diaza-s-indacene (IV), dyes for red light emitting materials such as Nile red (V); rhodamine dyes, cyanine dyes that emit red light, 1-ethyl-2- (4- (p- Pyridine dyes such as dimethylaminophenyl) -1,3-butadienyl) -pyridium-perchlorate (pyridine 1), oxazine dyes, etc .: known in the art such as coumarin dyes and naphthalimide dyes that emit green light Including any that are.

The light conversion material portion 512 may include a host material in addition to the color conversion pigment. By co-depositing both of them and dispersing the color conversion dye in the host material, it is possible to suppress a decrease in color conversion efficiency due to concentration quenching. In addition, the efficiency of color conversion can also be improved by using a material that can absorb light emitted from the carrier recombination layer 53 and transfer energy to the color conversion dye as the host material. It is desirable to use a low molecular weight material that can be deposited as the host material, such as tris (8-hydroxyquinolinate) aluminum (Alq ₃ ) or tris (4-methyl-8-hydroxyquinolinate). Aluminum complexes such as aluminum (Almq ₃ ), 4,4′-bis (2,2-diphenylvinyl) biphenyl (DPVBi), 2,5-bis- (5-tert-butyl-2-benzoxazolyl) Including thiophene.

The linear conductor 511 is preferably made of carbon nanotubes. The light-converting material portion 512 is formed by vapor deposition on the first electrode in which the carbon nanotubes are dispersed and arranged at a desired surface density, whereby the PL light-emitting carrier non-bonding layer 51 is obtained.
Carbon nanotubes can be formed upright at selectively required locations on a substrate by a plasma CVD method using a metal catalyst such as Co or Ni (see Patent Document 9 and Patent Document 11). For example, when Ni is formed to a thickness of 2 to 5 nm on a substrate and heated to 500 to 600 ° C., a nanoparticle dispersed on the substrate is obtained. Further, metal nanoparticles can be synthesized by reducing metal ions in a minute space surrounded by a surfactant by the reverse micelle method. It is common to prevent the coalescence and aggregation of nanoparticles by adding a dispersant in advance. In the present invention, it is preferable to form the metal catalyst so as to cover an area of 3 to 20% of the first electrode main surface. Further, according to the above-described method, the arrangement of the catalysts is random, but may be regularly arranged. Furthermore, in the present invention, carbon nanotubes may be grown in a columnar shape on another ground and transferred onto the first electrode to form a linear conductor.

In order for the carrier non-bonding layer to have a desired light conversion intensity, the diameter of the linear conductor is 5 nm to 30 nm, and the density of the linear conductor is 40 to 2000 / μm ² on the first electrode. It is preferable to dispose the catalyst so as to disperse and grow. The preferred length of the linear conductor is 40 nm to 100 nm. The linear conductor includes an island-shaped (dot-shaped) conductor.
FIG. 3 is a schematic view showing another embodiment of the organic EL element of the present invention, which is a cross-sectional view including a linear conductor and viewed from the long side direction of the first electrode.

  The organic EL element shown in FIGS. 1 and 3 includes an organic EL layer 50 sandwiched between a first electrode 30 and a second electrode 40, and the organic EL layer includes at least a carrier recombination layer 53 and a carrier non-bonding layer. 51 in common. On the other hand, in the organic EL element shown in FIG. 3, the organic EL layer is in reverse order in terms of function with respect to the layer configuration of FIG. 1, and the carrier non-bonding layer has a color conversion function. Although common, it differs in that it functions as an electron injection layer.

  And in the example of FIG. 3, the 1st electrode 30 is a reflective electrode which consists of the metal layer 31 and the protective layer 32 which covers this, and the 2nd electrode 40 is a transparent electrode. A part of the EL light emitted from the carrier recombination layer 53 is converted into PL light when passing through the carrier non-bonding layer 51, and the PL light reflected by the first electrode is mixed with the EL light and has a different wavelength distribution. The emitted light is emitted from the second electrode side to the outside of the organic EL element. In the figure, a region indicated by reference numeral 60 is a pixel separation film.

Hereinafter, a method for manufacturing the organic EL element having the carrier non-bonding layer shown in FIG. 1 will be described.
FIG. 4A is a cross-sectional view showing a process of forming a striped or strip-shaped first electrode 30 (anode) on the substrate 20. A plurality of first electrodes are formed substantially parallel to a direction parallel to the paper surface. Each first electrode includes a main surface substantially parallel to the substrate and a side surface continuous to the main surface. A pixel region is formed on the main surface.

FIG. 4B is a cross-sectional view showing a process of forming the metal catalyst 510 on the first electrode 30. The metal catalyst 510 is patterned in a portion corresponding to the pixel region.
FIG. 4C is a cross-sectional view showing a process of growing the linear conductor 511 on the metal catalyst 510. The linear conductor is preferably a carbon nanotube, and is formed by a plasma CVD method.

  FIG. 4D is a cross-sectional view showing a process of forming the light conversion material portion 512 on the structure shown in FIG. The light conversion material part is formed by vapor-depositing one or more kinds of color conversion dyes on the surface of the first electrode including the periphery of the linear conductor 511. Or it is good also as a light conversion material part by vapor-depositing a color conversion pigment | dye with a host material. Thus, the carrier non-bonding layer 51 including the light conversion material portion and the linear conductor is formed. The film thickness of the light conversion material portion is preferably such that the surface thereof is flush with the tip of the linear conductor or the tip is exposed from the surface. By passing the linear conductor through the carrier non-bonding layer, the non-bonding layer can have sufficient carrier transport capability.

  FIG. 4E is a cross-sectional view showing a process of forming the carrier recombination layer 53 and the like on the carrier non-bonding layer 51. A hole transport layer 52 as one conductive carrier transport layer, a carrier recombination layer 53 as an organic light emitting layer, an electron transport layer 54 as another conductive carrier transport layer, and an electron injection layer 55 as another conductive carrier injection layer are deposited. It is formed by a dry process. These layers and the carrier non-bonding layer 51 as the hole injection layer constitute the organic EL layer 50. Finally, the second electrode 40 (cathode) is formed on the organic EL layer.

In the above description, the organic EL element in which the first electrode is an anode and the carrier non-bonding layer is a hole injection layer has been described. When taking out light from the 1st electrode 30 side, it is better to make the 1st electrode 30 hole injection property.
On the other hand, as shown in FIG. 3, it is possible to manufacture an organic EL element having a reverse junction in which the first electrode is a cathode and the carrier non-bonding layer is an electron injection layer. In the case of extracting light from the second electrode 40 side, it is more advantageous to make the first electrode 30 electron injecting from the viewpoint of damage countermeasures when forming the second electrode. An electron transport layer, a carrier recombination layer, a hole transport layer, and a hole injection layer are stacked on the carrier non-bonding layer. The second electrode functions as an anode.

Hereinafter, each configuration will be further described.
The substrate 20 should be able to withstand the conditions used for forming a layer (described later) laminated thereon, and preferably has excellent dimensional stability. Preferably, a resin film or sheet such as quartz, glass plate, polyester, polymethyl methacrylate, polycarbonate, polysulfone, or the like can be used as the substrate 20.

A first electrode 30 is stacked on the substrate 20.
When the first electrode 30 is used as an anode as in the example of FIG. 1, the material is made of a material having a work function of 4.7 eV or higher and having a work function of not less than 4.7 eV in order to reduce the energy barrier for hole injection. Selected. When the light from the carrier recombination layer 53 is extracted from the first electrode side, it is desirable that the first electrode is light transmissive (having a transmittance of 80% or more with respect to visible light). Such light-transmitting anodes include, for example, conductive inorganic compounds, which are general transparent electrode materials, ITO (indium tin oxide), IZO (indium zinc oxide), SnO ₂ , ZnO ₂ , TiN can ZrN, HfN, TiOx, VOx, CuI, InN, GaN, be formed by using a _{CuAlO 2, CuGaO 2, SrCu 2} O 2, LaB 6, RuO 2. These substances are formed by vacuum deposition or sputtering.

  When the first electrode is a cathode as in the example of FIG. 3, the material is usually selected from materials having a work function of 4.3 eV or less and a work function of less than 4.3 eV in order to reduce the energy barrier for electron injection. Is done. When light from the carrier recombination layer 53 is taken out from the second electrode 40 side as an anode, the first electrode is preferably provided with light reflectivity (preferably having a visible light reflectance of 90% or more).

  The first electrode 30 has a laminated structure of a metal layer 31 and a protective layer 32. For the metal layer, Ag or an Ag alloy having good electron injection properties and light reflectivity is used. Techniques using an Ag alloy as a light-reflective cathode are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2003-077681 and 2003-234193. It is known that the Ag alloy has a high visible light reflectance in the entire blue to red region. On the other hand, an oxide transparent conductive film is used for the protective layer on the surface of the Ag alloy. By forming the protective layer, problems with the Ag alloy include, for example, high reactivity with oxygen and alkaline chemicals, and adhesion with silicon oxide or silicon nitride oxide that may be formed as the pixel isolation film 60. It is possible to avoid bad points.

Such a laminated structure of the first electrodes 30 is formed by ordinary photolithography. For example, an Ag layer is first formed on the entire surface of the substrate 20 by sputtering and patterned into a stripe shape to form a metal layer. Next, a transparent oxide is formed on the entire surface of the substrate 20 by sputtering, and patterned into a stripe shape so as to cover the metal layer to form a protective layer.
The organic EL element 10 of the present invention has a structure in which an organic EL layer 50 is held between a pair of first electrode 30 and second electrode 40. The organic EL layer includes at least a light emitting layer and has a structure in which a hole injection layer, a hole transport layer, an electron transport layer and / or an electron injection layer are interposed as required. Alternatively, a hole injection / transport layer having both hole injection and transport functions and an electron injection / transport layer having both electron injection and transport functions may be used. Specifically, an organic EL element having the following layer structure is employed.

(1) Anode / light emitting layer / cathode (2) Anode / hole injection layer / light emitting layer / cathode (3) Anode / light emitting layer / electron injection layer / cathode (4) Anode / hole injection layer / light emitting layer / electron Injection layer / cathode (5) Anode / hole transport layer / light emitting layer / electron injection layer / cathode (6) Anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode (7) Anode / Hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode All layers of the organic EL layer other than the organic light emitting layer which is the carrier recombination layer 53 are PL light emitting color conversion. Can be used as a layer. One or more of a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a hole injection transport layer, or an electron injection transport layer can be used as the color conversion layer. Two or more color conversion layers can also be used as two different types of layers. In the present invention, at least one of the color conversion layers is formed as the carrier non-bonding layer 51 between either the first electrode or the second electrode and the carrier recombination layer so as to be in contact with any of the electrodes. The carrier non-bonding layer including the linear conductor in contact with the electrode can effectively transport the carriers injected from the electrode.

The electron injection layer has an excellent electron injection effect of injecting electrons more smoothly and efficiently into the electron transport layer and / or carrier recombination layer. It is preferable to impart a color conversion function to the electron injection layer and further disperse the linear conductor to form a carrier non-bonding layer.
The electron transport layer transports injected electrons to the carrier recombination layer with high efficiency and prevents holes from moving into the electron transport layer.

  The carrier recombination layer serves as a light-emitting layer for reusing electrons transported from the cathode through the electron injection layer and electron transport layer and holes injected from the anode through the hole injection layer and hole transport layer. Combine. Depending on the energy released by the recombination, the recombination layer emits blue to blue-green light. As a material for the carrier recombination layer, an oxazole metal complex, a distyrylbenzene derivative, a styrylamine-containing polycarbonate, an oxadiazole derivative, an azomethine zinc complex, or an aluminum complex can be used.

  Alternatively, the carrier recombination layer can be formed by using the above-mentioned material as a host and, if necessary, doping a blue fluorescent dye. As a material that can be used for doping the carrier recombination layer, various light-emitting organic substances can be used. Any known ones: anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, quinoline metal complex, Tris (8-hydroxyquinolinato) aluminum complex, tris (4-methyl-8-hydroxyquinolinato) aluminum complex, tris (5-phenyl-8-hydroxyquinolinato) aluminum complex, aminoquinoline metal complex, benzo Quinoline metal complex, tri- (p-terphenyl-4-yl) amine, 1-aryl-2,5-di (2-thienyl) pyrrole derivative, pyran, quinacridone, distyrylbenzene derivative, distilly Emissions derivatives, and a group consisting of light-emitting compound is one having a part of the molecule, but not limited thereto. In addition to fluorescent dye-derived compounds typified by these compounds, light-emitting materials capable of phosphorescence emission from a triplet state can be suitably used.

  The hole transport layer in this embodiment has an excellent hole transport effect of transporting holes more smoothly and efficiently to the carrier recombination layer and prevents electrons from moving into the hole transport layer. To do. The hole transport layer can be formed using a material having a triarylamine partial structure, a carbazole partial structure, or an oxadiazole partial structure. Materials that can be used preferably include TPD, [alpha] -NPD, MTDAPB (o-, m-, p-), m-MTDATA, and the like.

As a material for the hole injection layer, Pc (including CuPc) or indanthrene compounds can be used. A material that is not easily damaged by sputtering when the transparent second electrode is formed by sputtering or the like is preferable. Note that these materials can be used to form a carrier non-bonding layer as a hole injection layer.
A second electrode is stacked on the carrier recombination layer. The second electrode functions as either a cathode or an anode.

  When the second electrode is used as a cathode, the material is usually selected from materials having a low work function having a work function of 4.3 eV or less in order to reduce the energy barrier for electron injection. In the case where light from the carrier recombination layer is extracted from the side of the first electrode as the anode, the second electrode is desirably provided with light reflectivity (preferably having a visible light reflectance of 90% or more). An example of such a material is aluminum.

  When the second electrode is used as an anode, the material is selected from a material having a high work function having a work function of 4.7 eV or more in order to reduce the energy barrier for hole injection. When light from the carrier recombination layer is extracted from the second electrode side, the second electrode is preferably light transmissive (having a transmittance of 80% or more with respect to visible light). Such a light-transmitting anode can be formed using a conductive inorganic compound exemplified as a material when the first electrode is an anode. These substances are formed on the hole injection layer or the like by vacuum deposition or sputtering.

The film thickness of the carrier non-bonding layer may be the same as the height of the linear conductor, for example, the carbon nanotube, or the height of the carbon nanotube may be as thin as 5 nm at the maximum.
In the case where light is extracted from the first electrode side as in the example of FIG. 1, it is preferable that the first electrode has a hole injecting property. The light conversion material part containing a red pigment is formed to the height of the carbon nanotube, the hole transport layer is formed from 20 nm to 40 nm, the carrier recombination layer emitting blue light is formed from 20 nm to 40 nm, and the electron transport layer is formed from 20 nm to 40 nm. Then, an electron injection layer is formed to a thickness of 0.5 nm to 5 nm, and a second electrode layer made of a metal material is formed to a thickness of 100 nm to 200 nm by an evaporation method.

  In the case where light is extracted from the second electrode side 40 as in the example of FIG. 3, it is more advantageous from the viewpoint of damage countermeasures when the second electrode is formed that the first electrode 30 has electron injectability. A light conversion material portion containing a red pigment is formed to the height of the carbon nanotube, an electron transport layer 54 is formed from 20 nm to 40 nm, a carrier recombination layer 53 emitting blue light is formed from 20 nm to 40 nm, and a hole transport layer 52 is formed. 20 nm to 40 nm are formed, the hole injection layer is formed to 60 nm to 200 nm, and the second electrode layer 40 made of a transparent oxide is formed to 200 nm to 300 nm by sputtering.

Since the EL light in the carrier recombination layer 53 is non-directional, a part of the EL light passes through the carrier non-coupling layer, undergoes wavelength distribution conversion, and is converted into PL light. By mixing the PL light and the EL light from the carrier recombination layer, emitted light as the whole organic EL element can be obtained. The emitted light is preferably white light.
Further, in the organic EL device of the present invention, the transparent electrode, which is a problem of the external CCM system in which the carrier non-bonding layer for performing color conversion by PL emission is inside the organic EL device and the color conversion layer is formed outside the device. EL light can be incident on the PL light-emitting carrier non-bonding layer without being affected by total reflection at the interface. Therefore, it is possible to convert EL light into PL light more efficiently and obtain light of a desired hue (for example, white light).

  Furthermore, for a specific PL emission color conversion dye, the quantum yield of absorption of specific excitation light (EL light) is constant, and the emission intensity of the color conversion dye changes in proportion to the EL emission intensity. Therefore, the organic EL element of the present invention is less likely to change its emission spectrum due to changes in driving voltage and current, and can stably emit light having a desired hue. Furthermore, even if the intensity of EL light from the light emitting layer changes as the cumulative energization time for the organic EL element increases, the emission intensity of PL light also changes following the change. It is possible to emit light stably while maintaining the hue.

(Example 1)
It is an example which produces the organic EL element for evaluation concerning the present invention. An organic EL element was formed on a substrate 20 made of 50 mm × 50 mm × 1.1 mm fusion glass (Corning 1737 glass). The manufacturing method is shown below.
As a transparent first electrode, 200 nm of ITO was formed on the entire surface of the substrate. On this ITO layer, Co nanoparticles having a diameter of 5 nm obtained by the reverse micelle method were cast on a substrate and dispersed almost uniformly over an area equivalent to 5% of the ITO area. This substrate was grown in a plasma CVD apparatus with a discharge power of 900 W, a gas pressure of 0.5 Torr, a mixed gas ratio of acetylene / argon = 9/1, a substrate temperature of 600 ° C., and a single carbon nanotube having a diameter of 5 nm was grown on each nanoparticle by 40 nm. It was. The number of carbon nanotubes was 300 / μm ² . The unit Torr corresponds to 133.322 Pa.

  Next, DCJTB as a color conversion dye and coumarin 6 as a second host material are placed in separate crucibles of a vacuum evaporation apparatus, and each crucible is controlled separately and heated to form coumarin 6. Film formation was performed at a film speed of 0.1 nm / second and a DCJTB film formation speed of 0.002 nm / second. Film formation was performed until the film thickness of the coumarin 6 was 40 nm, and the light conversion material portion 512 was formed.

Further, the hole transport layer 52, the organic light emitting layer 53, the electron transport layer 54, and the electron injection layer 55 were laminated on the substrate on which the light conversion material portion 512 was formed without breaking the vacuum. The hole transport layer 52 is 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) having a thickness of 25 nm, and the organic light-emitting layer 53 is 4,4 nm having a thickness of 30 nm. 4′-bis (2,2-diphenylvinyl) biphenyl (DPVBi), the electron transport layer 54 was Alq _{3 with} a thickness of 20 nm, and the electron injection layer 55 was LiF with a thickness of 1 nm.

Next, without breaking the vacuum, an Al film having a thickness of 150 nm was deposited by an evaporation method, and the second electrode 40 was formed as a cathode to obtain an organic EL element having the same structure as FIG.
(Example 2)
It is another example which produces the organic EL element for evaluation concerning the present invention.
On the same substrate 20 as in Example 1, an Ag-2 at% Mg alloy target as a reflective first electrode was formed on the entire surface by sputtering. Next, a transparent electrode (IZO) was formed on the entire surface as a protective layer for the Ag alloy layer by sputtering. Thereby, a reflective cathode having an Ag layer / IZO layer laminated structure was obtained.

Next, 60 nm of carbon nanotubes were grown in the same manner as in Example 1 except that the diameter of the Co nanoparticles was 10 nm, the diameter of the carbon nanotubes was 10 nm, and the number was 100 / μm ² .
Next, an electron injecting color conversion layer was formed, and the film was formed in the same manner as in Example 1 until the film thickness of coumarin 6 reached 60 nm, thereby forming a light conversion material portion. The area ratio of the carbon nanotube to the first electrode was 10%.

Furthermore, the electron transport layer 54, the organic light emitting layer 53, the hole transport layer 52, and the hole injection layer 56 were laminated on the substrate on which the light conversion material portion was formed without breaking the vacuum. The electron transport layer 54 is Alq _{3 with} a thickness of 20 nm, the organic light emitting layer 53 is 4,4′-bis (2,2-diphenylvinyl) biphenyl (DPVBi) with a thickness of 30 nm, and the hole transport layer 52 is a thickness. It was 20 nm of 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD), and the hole injection layer 56 was copper phthalocyanine (CuPc) with a thickness of 100 nm.

Next, without breaking the vacuum, an IZO film having a thickness of 200 nm was deposited by facing sputtering to form the second electrode 40 as an anode, thereby obtaining an organic EL element having a structure similar to that shown in FIG.
(Comparative Example 1)
In Example 1, an organic EL device was produced in the same manner as in Example 1 except that the dispersion area of Co nanoparticles was 1% of the ITO area and the number of carbon nanotubes grown was 100 / μm ² .

(Comparative Example 2)
An organic EL device was produced in the same manner as in Example 1 except that the dispersion area of Co nanoparticles was 30% of the ITO area and the number of carbon nanotubes grown was 3500 / μm ² in Example 1.
(Evaluation)
When the organic EL elements of Examples 1 and 2 were made to emit light, white light with luminance of 300 and 250 cd / m ² was emitted at an operating voltage of 10 V, respectively. All the elements had CIE-xy chromaticity coordinates (x = 0.29, y = 0.31). On the other hand, in order to obtain the same luminance as that of Example 1, the organic EL element of Comparative Example 1 needed to have an operating voltage of 15 V and had poor performance. In Comparative Example 2, the CIE-xy chromaticity coordinates (x = 0.26, y = 0.29) and the red contribution were slightly low at an operating voltage of 10 V, and a good white color was not obtained.

  The organic EL device of the present invention is expected to be applied to a backlight for producing a monochrome display and a white backlight for a full color organic EL display using a color filter system (for example, using RGB color filters).

It is a schematic diagram which shows one Embodiment of the organic EL element of this invention, Comprising: It is sectional drawing seen from the short side direction of the 1st electrode along a linear conductor. It is principal part sectional drawing which shows an example of the carrier non-bonding layer of this invention. It is a schematic diagram which shows another embodiment of the organic EL element of this invention, Comprising: It is sectional drawing seen from the long side direction of the 1st electrode along a linear conductor. It is sectional drawing seen from the short side direction of the 1st electrode which shows the Example of the manufacturing method of an organic EL element, (a)-(e) is sectional drawing which shows each process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Organic EL element 20 Substrate 30 1st electrode 40 2nd electrode 50 Organic EL layer 51 Carrier non-bonding layer 510 Metal catalyst 511 Linear conductor 512 Photoconversion material part 52 Hole transport layer 53 Carrier recombination layer 54 Electron transport layer 55 Electron injection layer 56 Hole injection layer

Claims (17)

An organic EL element comprising an organic EL layer sandwiched between a first electrode and a second electrode,
The organic EL layer includes at least a carrier recombination layer and a carrier non-bonding layer,
The carrier recombination layer emits electroluminescence light;
The carrier non-bonding layer is dispersed in the non-bonding layer with a light conversion material portion containing one or more color conversion dyes that emit photoluminescence light having energy lower than that of the electroluminescence light. An organic EL device comprising a nanoscale linear conductor formed in a transport direction. The organic EL element according to claim 1, wherein the linear conductor is made of carbon nanotubes. ^2. The organic EL element according to claim 1, wherein the linear conductor has a diameter of 5 nm to 30 nm and is formed on the surface of the first electrode in a density of 40 to 2000 lines / μm ² . The organic EL device according to claim 1, wherein the electroluminescence light is blue light or blue-green light having a peak wavelength at 400 nm to 500 nm. The organic EL element according to claim 1, wherein the light conversion material part further includes a host material that absorbs the electroluminescence light. 2. The organic EL according to claim 1, wherein the carrier non-bonding layer is formed between the first electrode and the carrier recombination layer, and the linear conductor is grown on a catalyst formed on the surface of the first electrode. element. The organic EL device according to claim 6, wherein a main component of the catalyst is Co or Ni. The organic EL device according to claim 1, wherein the carrier non-bonding layer is a hole injection layer. The organic EL device according to claim 8, wherein the first electrode is an anode. The organic EL device according to claim 1, wherein the carrier non-bonding layer is an electron injection layer. The organic EL device according to claim 10, wherein the first electrode is a cathode. The organic EL element according to claim 1, wherein the light conversion material part is formed by vapor deposition. A method for producing an organic EL element comprising an organic EL layer sandwiched between a first electrode and a second electrode,
The organic EL layer includes at least a carrier recombination layer and a carrier non-bonding layer,
Forming a first electrode on a substrate;
Forming a linear conductor on the first electrode;
A step of evaporating a light conversion material portion containing one or more color conversion dyes around the linear conductor to form the carrier non-bonding layer;
And a step of forming the carrier recombination layer on the non-bonding layer. The method of manufacturing an organic EL element according to claim 13, wherein the linear conductor is made of carbon nanotubes. The method of manufacturing an organic EL element according to claim 13, wherein in the step of forming the linear conductor, a catalyst is formed on the first electrode, and the linear conductor is grown on the catalyst. The method for producing an organic EL element according to claim 15, wherein a main component of the catalyst is Co or Ni. 14. The manufacturing of an organic EL device according to claim 13, wherein in the step of forming the linear conductor, the linear conductor is formed by transferring the linear conductor grown in a columnar shape by a CVD method onto the first electrode. Method.