JP2006086096A - Organic EL display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high luminance organic EL display element capable of increasing the light emission efficiency to the outside.
An organic EL device of the present invention includes a light emitting unit including at least a support substrate, an organic EL layer having at least a first electrode, an organic light emitting layer, and a second electrode, a transparent substrate, and a color conversion filter. An organic EL display element having a layer and a color conversion filter substrate including at least a passivation film bonded to each other, wherein the transparent substrate has a plurality of right-angle conical shapes on a surface opposite to the color conversion filter layer. The protrusions are provided in an array.
[Selection] Figure 2

Description

  The present invention relates to an organic EL (electroluminescence) display element, and more particularly to a high-brightness organic EL display element that can ultimately increase the light emission efficiency to the outside. The present invention also relates to a color conversion filter substrate that can be used in the organic EL display element.

An organic EL element (organic electroluminescence element) has a low driving voltage required for electroluminescence, and can select a luminescent color by selecting a luminescent material. , 530, 325 (Patent Document 1)). Among them, for the purpose of improving the luminous efficiency, a luminance of 1000 Cd / m ² or more was obtained with a driving voltage of 10 V or less using a laminated organic EL element composed of an anode / hole injection layer / light emitting layer / cathode. (Japanese Examined Patent Publication No. 57-51781 (Patent Document 2)) has been made, and research has been actively conducted since then.

  On the other hand, considering the application of organic EL elements to display elements, multicolor display is necessary. As a multicolor display method, there can be considered one in which three primary color EL elements are sequentially buttered and arranged on a plane, and a white light emitting element is provided with three primary color (red, green, and blue) color filters.

  However, the patterning of the EL element lowers the element efficiency and makes the process very complicated, making mass production difficult. In addition, the color filter method requires a white light emitting element having a stable and sufficient luminance, but at present, such a white light emitting element has not been obtained. Therefore, in recent years, a color conversion method using a fluorescent material that absorbs light in the light emission region of the organic EL element and emits fluorescence in the visible light region has been proposed (Japanese Patent Laid-Open Nos. 3-152897 and 5-258860). Gazette (patent documents 3, 4)).

  A configuration of an organic EL display element adopting a color conversion method is, for example, as shown in FIG. This organic EL display element includes a light emitting unit 10 as a first member and a color conversion filter substrate 20 as a second member, and each has a structure in which they are opposed to each other via supports SUP1 and SUP2. Have. The light emitting unit 10 includes a reflection mirror MIR provided on a glass substrate GL1 that is a support substrate, and an organic EL layer EML (including a cathode, an organic light emitting layer, an anode, and the like) formed thereon. The color conversion filter substrate 20 is provided with a color conversion filter layer (fluorescent light emitting layer and / or color filter) EL and a passivation film PL on one surface of a glass substrate GL2 which is a transparent substrate. Here, the gap GAP is usually filled with a material having a refractive index lower than that of the passivation film PL, the color conversion filter layer EL, and the transparent glass substrate GL2.

  The operation of the organic EL display element shown in FIG. 1 is as follows. The light emitted from the organic EL layer reaches the color conversion filter substrate 20 directly or through the mirror MIR, is converted to a predetermined wavelength through the color conversion filter, is emitted to the external AIR, and reaches the viewer's eyes EYE. Will be visually recognized.

US Pat. No. 3,530,325 Japanese Patent Publication No.57-51781 Japanese Patent Laid-Open No. 3-152897 JP-A-5-258860

  In the conventional organic EL display element shown in FIG. 1, generally, a transparent substrate CL2 of a color conversion filter having a flat front surface and a front surface is used. For this reason, the fluorescence emitted from the color conversion filter layer causes total reflection in the inside, and all of the fluorescence may not be observed by the viewer, resulting in light loss. The phenomenon will be described with reference to FIG. For example, consider light from the bright spot LP of the color conversion filter layer. If this light travels along the light path represented by arrows a, b, c, d, and e, for example, the light of b, c, and d is emitted to the external AIR and is effectively observed by the viewer. Light. However, the light of a and e is totally reflected at the boundary between the transparent substrate GL2 and the external AIR, and the light totally reflected is also totally reflected at the boundary between the color conversion filter layer EL and the transparent substrate GL2 (this is Usually because they have approximately the same refractive index). By repeating this, the lights a and e are guided to the side surface of the organic EL display element and cannot be used as effective light.

  As described above, the conventional organic EL display element has a problem that the amount of light that can be extracted to the outside out of the light generated inside the display element is reduced by the optical waveguide by total reflection.

The present invention has been made to solve the above problems, and firstly, it relates to an organic EL display element capable of increasing the efficiency of extracting light to the outside. In one embodiment, the organic EL display element of the present invention includes a light emitting unit including at least a support substrate, an organic EL layer having at least a first electrode, an organic light emitting layer, and a second electrode, a transparent substrate, and color conversion. A filter layer and a color conversion filter including at least a passivation film are attached to face each other, and the transparent substrate has a plurality of right-angle conical protrusions arrayed on the surface opposite to the color conversion filter layer. It was provided in the shape.
In another embodiment, the right conical protrusion is a flattened top of a right conical shape.
The second aspect of the present invention relates to a color conversion filter substrate. The color conversion filter substrate of the present invention includes at least a transparent substrate, a color conversion filter layer, and a passivation film, and the transparent substrate has a right-angle cone on the surface opposite to the color conversion filter layer. A plurality of protrusions are provided in an array. In the color conversion filter substrate of the present invention, the right conical protrusion may be a flattened top of a right conical shape.
In the organic EL display element and the color conversion filter substrate of the present invention, the transparent substrate is preferably glass.

  According to the present invention, there is provided an organic EL display element capable of effectively extracting light that has been totally reflected at the interface between the conventional glass and the outside and has not been emitted to the outside, and has high light extraction efficiency. Can do.

  The first aspect of the present invention relates to an organic EL display element, and the organic EL display element includes a light emitting unit including at least a support substrate and an organic EL layer having at least a first electrode, an organic light emitting layer, and a second electrode, and A transparent substrate, a color conversion filter layer, and a color conversion filter including at least a passivation film are attached to face each other, and the transparent substrate has a right-angle cone on the surface opposite to the color conversion filter layer. A plurality of protrusions are provided in an array.

  The present invention will be described below with reference to the drawings (FIGS. 2 to 4). FIG. 2 is a diagram showing a first embodiment of the organic EL display element of the present invention. FIG. 2A is a schematic cross-sectional view of an organic EL display element, and FIGS. 2B and 2C are a schematic view and a transparent view, respectively, of the transparent substrate of the display element as viewed from the outside. It is a schematic sectional drawing of a board | substrate.

  As shown in FIG. 2A, the organic EL display element of the present invention includes a light emitting unit 40 as a first member and a color conversion filter substrate 30 as a second member, each of which is a support SUP1. And a structure in which they are bonded to each other via SUP2. The light emitting unit 40 is obtained by forming an organic EL layer EML (including a first electrode, an organic light emitting layer, a second electrode, and the like) on a glass substrate GL1 that is a support substrate. The color conversion filter substrate 30 is provided with a color conversion filter layer (fluorescent light emitting layer and / or color filter) EL and a passivation film PL on one side of a glass substrate GL2 which is a transparent substrate.

  A mirror MIR can be provided between the support substrate GL1 and the organic EL layer EML. The gap GAP is preferably filled with a material having a refractive index lower than that of the passivation film PL, the color conversion filter layer EL, and the transparent glass substrate GL2. In FIG. 2, the color conversion filter layer is described as one type of layer, but a plurality of these pixels may be provided so that the three primary colors of red, green, and blue can be emitted. In the present invention, the light emitting unit may be a passive drive system or a TFT drive system.

  The present invention is characterized by the transparent substrate of the color conversion filter substrate. That is, as shown in FIGS. 2B and 2C, on the surface opposite to the surface on which the color conversion filter layer of the transparent substrate GL2 is provided (that is, the outer surface of the organic EL display element) An array of right conical protrusions is formed. The protrusion has a height of 0.1 μm to 5 μm, preferably 0.2 μm to 1 μm. The array of protrusions is formed with a pitch of 0.2 μm to 10 μm, preferably 0.4 μm to 2 μm.

  In the color conversion method, the light from the organic EL layer is once absorbed by the color conversion filter layer, and the light emitted after wavelength conversion is used for display. Since the light emitted from the color conversion filter layer is isotropic, a right-angled conical shape having a circular bottom surface, which can easily capture many light beams, is most preferable in order to effectively suppress the total reflection.

  Further, by providing the projections as described above, when light is emitted from the transparent substrate GL2 to the external AIR, the incident angle of the light to these interfaces is an angle that is not totally reflected, so that the conventional organic EL display element This eliminates the problem of wave guiding in the transparent substrate GL2, which increases the efficiency of extracting light to the outside.

  This principle will be described with reference to FIG. FIG. 3 is an enlarged cross-sectional view of a right-angle conical protrusion according to this embodiment, and shows how light is reflected. In FIG. 3, let us consider light rays R1, R2, R3 and R4 incident on point P on the side surface of the protrusion. R1, R2 and R3 are emitted to the external AIR as R11, R21 and R31, respectively, without being totally reflected at the point P. On the other hand, the light ray R4 is totally reflected at the point P, becomes a light ray R41, and enters the point Q on another surface of the protrusion. Here, as shown in FIG. 3, if the vertex of the right-angle cone is O, the skirt point of the right-angle cone is O ′, and the light source direction of the light ray R4 is Q ′, the angle (O′PQ ′) is the angle (OPQ). And the angle (PQO) is equal to the following formula (1).

      Angle (PQO) = 180 ° −Angle (POQ) −Angle (OPQ) (1)

  Here, for example, the notation of the angle (OPQ) represents the angle of the angle OPQ of the line segments OP and QP with the point P as the vertex. Similarly, for example, the angle (O′PQ ′) represents the angle O′PQ ′ having the point P as a vertex.

  In the present invention, since the protrusion has a right-angle cone shape, the angle (POQ) is 90 °, and the above expression (1) can be expressed as the expression (1 ′).

      Angle (PQO) = 90 ° −Angle (OPQ) (1 ′)

Here, when the angle (OPQ) is the angle at which total reflection starts when the light ray R4 is gradually brought closer to the boundary surface between the transparent substrate GL2 and the external AIR, the transparent substrate is glass and the outside is air. According to Snell's law, this angle is sin ⁻¹ (1 / 1.5) = 41.8 °. Therefore, the angle (PQO) is 90 ° -41.8 ° = 48.2 °, which is larger than the angle 41.8 ° in the case of total reflection at the point Q. For this reason, the light ray R41 is not totally reflected at the point Q but becomes the light ray R411 and is emitted to the external AIR.

  In another embodiment of the present invention, as shown in FIG. 4, for example, protrusions with flattened tops of right-angle cone protrusions are arranged in an array. Here, FIG. 4A is a schematic view when the transparent substrate is viewed from the outside, and FIG. 4B is a schematic cross-sectional view of the transparent substrate. FIG. 4C is an enlarged cross-sectional view of the conical protrusion of this embodiment and shows how light is reflected.

  In the present invention, it is preferable to form a right-angle cone-like projection, but it is necessary to have a high degree of skill to sharpen the apex of the right-angle cone (for example, the point O in FIG. 3). Therefore, in this embodiment, as shown in FIGS. 4A to 4C, the top of the right-angle cone is flattened. In this embodiment, the reflection of light on the transparent substrate GL2 is as described with reference to FIG. 3 (see the relationship of reflection at the point P in FIG. 4C). On the other hand, in the flat portion at the top as represented by AA ′ in FIG. 4C, the totally reflected light cannot be taken out to the external AIR as in the case where a right-angle conical protrusion is provided. However, by making this AA ′ portion as small as possible, the light extraction efficiency can be improved to the extent that it is inferior to that of the above-described embodiment in which a right-cone-shaped protrusion is formed.

  In the present invention, the height of the removed portion of the apex of the right-angle cone protrusion, that is, the height from the apex of the right-angle cone protrusion to the flat portion AA ′ is the case where the height of the right cone protrusion is in the above range. 0.3 μm or less, preferably 0.2 μm or less, more preferably 0.1 μm or less.

  In this embodiment, by making the top of the right-angle cone protrusion slightly flat, it is easier to create an array structure while maintaining the same external light extraction effect as when the right-angle cone top is not flat. It becomes possible to do.

  In the present invention, the transparent substrate is not particularly limited as long as it can form protrusions, but is preferably a transparent glass substrate (particularly preferably a quartz glass substrate). In the case of a glass substrate, the protrusions can be produced by applying, for example, a dry etching technique (specifically, a method using reactive ion etching using a metal as a mask and a fluorine-based gas as a reactive gas). . Further, the transparent substrate on which the projection array is formed may be formed directly on the glass substrate by a dry etching technique, or an array of right-angle cone projections may be separately prepared and bonded to the transparent substrate GL2. In this case, it goes without saying that the separately formed projection array and the material of the transparent substrate GL2, for example, an adhesive for bonding, are preferably materials having the same refractive index so that total reflection does not occur. Absent.

  The second of the present invention relates to a color conversion filter substrate. The color conversion filter substrate of the present invention includes at least a transparent substrate, a color conversion filter layer, and a passivation film, and the transparent substrate has a right-angle cone on the surface opposite to the color conversion filter layer. A plurality of protrusions are provided in an array. In the color conversion filter substrate of the present invention, the right conical protrusion may be a flattened top of a right conical shape.

  The present invention will be described below with reference to the drawing (FIG. 5). FIG. 5 is a diagram showing a first embodiment of the color conversion filter substrate of the present invention. FIG. 5 is a schematic cross-sectional view of a color conversion filter substrate.

  As shown in FIG. 5, the color conversion filter substrate of the present invention corresponds to the color conversion filter 30 which is the second member described in the previous organic EL display element. That is, the color conversion filter 30 is a transparent substrate in which a color conversion filter layer (fluorescent light emitting layer and / or color filter) EL and a passivation film PL are provided on one side of a glass substrate GL2 which is a transparent substrate. However, a plurality of right-angle conical protrusions are provided in an array on the surface opposite to the color conversion filter layer.

  In another embodiment of the color conversion filter substrate of the present invention, the top of the right-angle conical protrusion is flat.

  These characteristics and various conditions such as the material of the transparent substrate and the method of forming the protrusions are as described above for the organic EL display element.

  Below, various conditions, such as the component of the organic electroluminescent display element and color conversion filter board | substrate of this invention, and a film-forming method, are demonstrated. In the following description, optional elements will also be described.

(I) Support substrate (GL1)
As the supporting substrate, an insulating substrate made of glass, plastic, or the like, or a substrate in which an insulating thin film is formed on a semiconductive or conductive substrate can be used. Alternatively, a flexible film formed from polyolefin, acrylic resin, polyester resin, polyimide resin, or the like may be used as the support substrate. Parameters such as the thickness of the support substrate are conventional and can be appropriately selected by those skilled in the art.

(II) Color Conversion Filter Layer Next, the color conversion filter layer provided on the support substrate will be described. Each color conversion filter layer is a red conversion filter layer, a green conversion filter layer, and a blue conversion filter layer made of red, green, and blue dyes or pigments, respectively.

  In this specification, the color conversion filter layer is a general term for a color filter layer, a fluorescence conversion layer, and a laminate of a color filter layer and a fluorescence conversion layer. The fluorescence conversion layer absorbs light in the near ultraviolet region or visible region emitted from the organic EL layer, particularly light in the blue or blue-green region, and emits visible light having a different wavelength as fluorescence. Each of the R, G, and B fluorescence conversion layers includes at least an organic fluorescent dye and a matrix resin. In order to enable full color display, an independent color conversion filter layer of at least a red (R) region, a green (G) region, and a blue (B) region is provided.

1) R, G, B color conversion filter layer In the present invention, at least one kind of fluorescent dye that emits fluorescence in the red region is used as the organic fluorescent dye, and is combined with one or more fluorescent dyes that emit fluorescence in the green region It is preferable. This is due to the following reason. When the organic EL layer is a light source, it is easy to obtain one that emits light in the blue to blue-green region. However, if this is changed to light in the red region through a simple red filter layer, the wavelength of the red region is originally Because there is little light, it becomes extremely dark output light. Therefore, in order to obtain light in the red region having a sufficiently strong output, it is necessary to temporarily absorb the light from the organic EL layer as the light emitter by the fluorescent dye and convert it into light in the red region. . As described above, the light in the red region can be output with sufficient intensity by converting the light from the light emitter into the light in the red region by the fluorescent dye.

  On the other hand, the light in the green region may be output by converting the light from the illuminant into the light in the green region by another fluorescent dye, or the light emitted from the illuminant is green. The light from this light emitter may simply be output through the green filter layer if it contains enough light in the region.

  As for the light in the blue region, light from the light source (for example, light from the organic EL layer) can be output through a simple blue filter layer.

(Organic fluorescent dye)
In the present invention, the organic fluorescent dye absorbs light in the near ultraviolet region or visible region, particularly light in the blue or blue-green region, emitted from a light emitter such as an organic EL layer, and has a wavelength different from that of the light emitter. As long as it emits visible light, it is not particularly limited. In the present invention, at least one type of fluorescent dye that emits fluorescence in the red region is used, and may be combined with one or more types of fluorescent color paper that emits fluorescence in the green region.

  Examples of fluorescent dyes that absorb blue to blue-green light emitted from the organic EL layer and emit red light include the following organic fluorescent dyes. That is, rhodamine dyes such as rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, sulforhodamine, basic violet 11, basic red 2, etc., cyanine dye, 1-ethyl-2- [4- (p -Dimethylaminophenyl) -13-butadienyl] -pyridium-perchlorate (pyridine 1) and other pyridine dyes or oxazine dyes. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used as long as they can emit desired fluorescence.

  Examples of fluorescent dyes that absorb blue to blue-green light emitted from the organic EL layer and emit green fluorescent light include the following organic fluorescent dyes. That is, 3- (2-benzothiazolyl) -7-diethylaminocoumarin (coumarin 6), 3- (2′-benzoimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 7), 3- (2′-N-methyl) Benzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 30), 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidine (9,9a, 1-gh) coumarin (coumarin 153 Or the like, or basic yellow 51 which is a coumarin dye-based dye, and naphthalimide dyes such as solvent yellow 11 and solvent yellow 116. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used as long as they can emit desired fluorescence.

  The organic fluorescent dye that can be used in the present invention includes polymethacrylate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer resin, alkyd resin, aromatic sulfonamide resin, urea resin, melamine resin, benzoguanamine resin, and An organic fluorescent pigment may be obtained by kneading into a resin mixture or the like in advance to obtain a pigment. In addition, these organic fluorescent dyes and organic fluorescent pigments (in the present specification, the above two are collectively referred to as organic fluorescent dyes) may be used alone, or two or more of them may be used to adjust the hue of fluorescence. May be used in combination. The organic fluorescent dye used in the present invention is contained in the color conversion filter layer in an amount of 0.01 to 5% by weight, more preferably 0.1 to 2% by weight, based on the weight of the color conversion filter layer. The When the content of the organic fluorescent dye is less than 0.01% by weight, sufficient wavelength conversion cannot be performed, and when the content exceeds 5%, color conversion efficiency is obtained due to effects such as concentration quenching. Decrease occurs.

2) Matrix resin Next, the matrix resin used for the color conversion filter layer of this invention is demonstrated. The matrix resin is made of a photocurable resin or a photothermal combination type curable resin. This is subjected to light and / or heat treatment to generate radical species and ionic species to be polymerized or cross-linked, to insolubilize the resin, and to form a color conversion filter layer and the like.

  Photocurable or photothermal combination type curable resins include (1) acrylic polyfunctional monomers and oligomers having a plurality of acryloyl groups and methacryloyl groups, (2) polyvinyl cinnamate, (3) chain or cyclic olefins, (4) Monomers having an epoxy group are included. In addition, the photocurable resin or photothermal combination type curable resin is preferably soluble in an organic solvent or an alkaline solution in a state where it is not cured as a color conversion filter layer.

  These curable resins are used as, for example, the following compositions, and are coated on a substrate and then patterned. For example, the curable resin (1) is mixed with light or a thermal polymerization initiator, and after applying the composition, it is subjected to light or heat treatment to generate photoradicals or thermal radicals for polymerization. Further, the curable resin (2) is mixed with a sensitizer, and after applying the composition, it is dimerized by light or heat treatment to be crosslinked. The curable resin (3) is mixed with bisazide, and after applying the composition, nitrene is generated by light or heat treatment to crosslink with the olefin. The curing agent (4) is mixed with a photoacid generator, and after applying this composition, an acid (cation) is generated and polymerized by light or heat treatment. In the present invention, the composition comprising the photocurable or photothermal combination curable resin (1) can be patterned with high definition, and is preferable in terms of reliability such as solvent resistance and heat resistance.

3) Color filter layer The color filter layer controls the transmittance of a specific wavelength. There are various color filter layers such as a film in which a pigment or dye is dispersed in a resin, a colored film vacuum-deposited, a multilayer film having a different refractive index, or a coloration on a substrate. Can also be adopted. For example, as a color filter layer made of a resin film in which a pigment is dispersed, a pigment such as phthalocyanine dispersed in a resin such as polyimide can be cited as an example.

4) Black matrix A black matrix will not be specifically limited if it absorbs visible light well and does not have a bad influence on a light emission part and a color conversion filter layer. In the present invention, the black matrix is preferably formed by a black inorganic layer, a layer in which a black pigment or a black dye is dispersed in a resin, or the like. For example, as the black inorganic layer, a chromium film (chromium oxide / chromium laminated film) and the like can be given. Moreover, as a layer which disperse | distributed black pigment or black dye to resin, what disperse | distributed pigments or dyes, such as carbon black, phthalocyanine, and quinacridone, to resin, such as a polyimide, a color resist, etc. are mentioned, for example. These black matrices can be formed by a wet process such as a dry process such as a sputtering method, a CVD method, or vacuum deposition, or a spin coating method, and can be patterned by a photolithography method or the like.

  In the present invention, the light reflectance of the black matrix is 40% or less, preferably 30% or less, more preferably 10% or less. If the reflectance is higher than this, incident light from the outside is reflected, which causes a decrease in contrast. In the present invention, the chromium film (several tens of percent) and the pigment-dispersed resin layer (10% or less) have preferable light reflectance, but the pigment-dispersed resin layer is preferable because it has a lower reflectance than the chromium film. . However, since the inorganic layer can have electrical conductivity depending on the material and may have a function as an auxiliary electrode of the transparent electrode, the material of the black matrix is the color conversion filter layer. What is necessary is just to select suitably according to a use. The black matrix preferably has a thickness of 0.5 to 2.0 μm.

(III) Passivation film (PL)
In the present invention, a passivation film is provided to cover the black matrix, the color conversion filter layer, the planarization layer, and the like on the support substrate. The passivation film is effective in preventing permeation of oxygen, low molecular components and moisture from the external environment, and preventing deterioration of the function of the organic EL layer due to them. Further, the passivation film preferably has high flatness so that the first electrode and the like formed thereon are not disconnected. Furthermore, the passivation film is preferably transparent in the emission wavelength region in order to transmit the light emitted from the organic EL layer to the outside.

In order to satisfy these requirements, the passivation film has high transparency in the visible region (transmittance of 50% or more in the range of 400 to 700 nm), electrical insulation, and barrier properties against moisture, oxygen, and low molecular components. Preferably, it is formed with the material which has the film hardness of 2H or more of pencil hardness. For example, materials such as inorganic oxides and inorganic nitrides such as SiO _x , SiN _x , SiN _x O _y , AlO _x , TiO _x , TaO _x , and ZnO _x can be used. The thickness of the passivation film is preferably 0.1 to 10 μm.

  In the present invention, the planarizing layer and the passivation film can be formed as one layer (surface smoothing layer) having both functions. In this case, the layer can be formed of any material known in the technical field, for example, the inorganic oxide, inorganic nitride, or the like.

  In the present invention, a color conversion filter layer corresponding to each color of RGB and a black mask positioned between and around them are formed on a transparent substrate to form a color conversion filter substrate. The color conversion filter layer can be formed by a conventional method using a spin coating method and a photolithographic method. The black mask can be formed by the procedure described above. Note that conical protrusions are provided on the surface of the transparent substrate opposite to the side on which the color conversion filter layer is provided by the above-described means.

  The method for forming the passivation film is not particularly limited. For example, it can be formed by a conventional method such as a dry method (sputtering method, vapor deposition method, CVD method, etc.) or a wet method (spin coating method, roll coating method, casting method, etc.).

(IV) TFT
The TFT is provided when active matrix driving is performed. The TFTs are arranged in a matrix on the support substrate, and a source electrode or a drain electrode is connected to a first electrode corresponding to each pixel. Preferably, the TFT is a bottom gate type in which a gate electrode is provided under a gate insulating film, and has a structure using a polycrystalline silicon film as an active layer.

  The wiring portion for the drain electrode and the gate electrode of the TFT, and the structure of the TFT itself can be created by a method known in the art so as to achieve the desired withstand voltage, off-current characteristics, and on-current characteristics. it can. In addition, in the organic EL display element of the present invention using the top emission method, since light does not pass through the TFT portion, it is not necessary to reduce the TFT in order to increase the aperture ratio, and the degree of freedom in designing the TFT can be increased. This is advantageous for achieving the above characteristics.

(V) Planarizing insulating film When performing active matrix driving, it is preferable to form a planarizing insulating film on the TFT. The planarization insulating film is provided in a portion other than the portion necessary for the connection between the source electrode or drain electrode of the TFT and the first electrode and the connection of other circuits, and planarizes the substrate surface to form a high-definition pattern of the subsequent layers. make it easier. The planarization insulating film can be formed of any material known in the art. _Preferably formed from _{SiO x, SiN x, SiN x} O y, AlO x, TiO x, TaO x, inorganic oxide or nitride such as ZnO _x, or polyimide or acrylic resin. The thickness of the planarizing layer is preferably 1 μm to 10 μm.

(VI) First Electrode, Organic EL Layer and Second Electrode The organic EL display element of the present invention has at least an organic light emitting layer sandwiched between a pair of electrodes, and if necessary, a hole injection layer, an electron injection layer, etc. It has the structure which introduced. That is, the organic EL display element of the present invention includes at least a first electrode, an organic EL layer including a hole injection layer, an organic light emitting layer, an electron transport layer, and the like, and a second electrode. Specifically, the first electrode, the organic EL layer, and the second electrode have the following layer structure.
(1) Anode / organic light emitting layer / cathode (2) Anode / hole injection layer / organic light emitting layer / cathode (3) Anode / organic light emitting layer / electron transport layer / cathode (4) Anode / hole injection layer / organic Light emitting layer / electron transport layer / cathode (5) anode / hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / cathode (6) anode / hole injection layer / hole transport layer / organic light emitting layer / Electron transport layer / electron injection layer / cathode

  In the above layer structure, it is desirable that at least one of the anode and the cathode is transparent in the wavelength range of light emitted from the organic EL layer. Light is emitted through this transparent electrode.

  In the present specification, the organic layer (organic light emitting layer, hole injection layer, hole transport layer, electron transport layer and / or electron injection layer) sandwiched between the first electrode and the second electrode is referred to as organic EL. This is called a layer. In this specification, the support substrate, the reflecting mirror, the first electrode, the organic EL layer, the second electrode, and the like are collectively referred to as a light emitting unit.

(I) Electrode and organic EL layer In the present invention, the following first electrode and second electrode can be used.

A) First electrode The first electrode may be either an anode or a cathode. When the first electrode is used as an anode, a material having a high work function is used in order to efficiently inject holes. In the top emission method as in the present invention, the first electrode does not need to be transparent, but the first electrode can be formed using a conductive metal oxide such as ITO or IZO. Further, when a conductive metal oxide such as ITO is used, it is preferable to use a metal electrode (Al, Ag, Mo, W, etc.) having a high reflectance underneath. Since this metal electrode has a lower resistivity than the conductive metal oxide, it functions as an auxiliary electrode, and at the same time, the light emitted from the organic EL layer can be reflected to the color conversion filter substrate side to effectively use the light. It becomes.

  When the first electrode is used as a cathode, it is an electron-injecting material made of an alkali metal such as lithium or sodium, an alkaline earth metal such as potassium, calcium, magnesium, or strontium, or a fluoride thereof. Metals, alloys and compounds with other metals are used. Similar to the above, a metal electrode (Al, Ag, Mo, W, etc.) having a high reflectance may be used underneath, and in that case, low resistance and effective use of light emission of the organic EL layer by reflection are achieved. be able to.

  When active matrix driving is performed in the organic EL display element of the present invention, the first electrode is formed on the planarization insulating film in a form separated corresponding to each TFT, and is connected to the source electrode or drain electrode of the TFT. . When connected to the source electrode, it functions as an anode, and when connected to the drain electrode, it functions as a cathode. The TFT and the first electrode are connected by a conductive plug filled in a contact hole provided in the planarization insulating film. The conductive plug may be formed integrally with the first electrode, or may be formed using a low-resistance metal such as gold, silver, copper, aluminum, molybdenum, or tungsten.

  Alternatively, when passive matrix driving is performed in the organic EL display element of the present invention, the first electrode in a line pattern shape is formed on the support substrate without forming the TFT and the planarization insulating film. Also in this case, the first electrode can be used as either an anode or a cathode. In the present invention, it is preferable to provide a reflective film (mirror) MIR described later, if necessary.

B) Second electrode The second electrode can efficiently inject electrons or holes into the organic light emitting layer. In the case of the present invention which is a top emission method, the second electrode is required to be transparent in the emission wavelength region of the organic EL layer. For example, the second electrode preferably has a transmittance of 50% or more, preferably 90% or more, for light having a wavelength of 400 to 800 nm.

  When the second electrode is used as a cathode in the top emission method, it is required to be transparent in the wavelength range of light emitted from the organic light emitting layer. Therefore, in this case, it is preferable to use a transparent conductive material such as ITO or IZO. In addition, the material of the second electrode is required to have a small work function in order to inject electrons efficiently. In order to satisfy both of the above-mentioned two characteristics of a small work function and transparency, in the present invention, the second electrode is a layer composed of a transparent electrode layer and a material having a small work function (this is the same as that in the organic light emitting layer). It corresponds to an electron injection layer.). In general, since a material having a small work function has low transparency, this is effective. For example, materials such as alkali metals such as lithium and sodium, alkaline earth metals such as potassium, calcium, magnesium and strontium, or electron injecting metals such as fluorides thereof, alloys and compounds with other metals, etc. An extremely thin film (10 nm or less) can be used. A material such as Al or Mg / Ag can also be used.

  By using these materials having a low work function, efficient electron injection can be performed, and by using an ultrathin film, it is possible to minimize the decrease in transparency due to these materials. A transparent conductive film such as ITO or IZO is formed on the ultrathin film. The ultrathin film functions as an auxiliary electrode, reduces the resistance value of the entire second electrode, and makes it possible to supply a sufficient current to the organic light emitting layer.

  When using the second electrode as the anode, it is necessary to use a material having a large work function in order to increase the hole injection efficiency. In the case of the top emission method, it is necessary to use a highly transparent material in order for light emitted from the organic light emitting layer to pass through the second electrode. Therefore, in this case, it is preferable to use a transparent conductive material such as ITO or IZO.

C) Organic EL layer Known materials can be used as the material of each layer of the organic EL layer. In order to obtain light emission from blue to blue-green, the organic light-emitting layer includes, for example, fluorescent brighteners such as benzothiazole, benzimidazole, and benzoxazole, metal chelated oxonium compounds, styrylbenzene compounds, Aromatic dimethylidin compounds are preferably used. As the electron injection layer, the material having a small work function described in the column of the electrode can be used. Therefore, the second electrode can also serve as an electron injection layer. As the electron transport layer, a metal complex (Alq3), oxadiazole, a triazole compound, or the like can be used. For the hole injection layer, aromatic amine compounds, starburst amines, benzidine amine multimers, copper phthalocyanine (CuPc), and the like can be used. As the hole transport layer, a starburst amine, an aromatic diamine, or the like can be used.

  The thicknesses of the first electrode, the second electrode, and the organic EL layer are as usual.

  A plurality of TFTs, a planarization insulating layer, a plurality of first electrodes, an organic EL layer, a second layer are formed on a supporting substrate by appropriately combining a sputtering method, a vapor deposition method, a coating method including a spin coating method, a photolithography method, and the like. An electrode and a passivation film can be sequentially stacked. When passive matrix driving is performed, a line pattern-shaped first electrode, organic EL layer, and first electrode are appropriately combined with a coating method including a sputtering method, a vapor deposition method, a spin coating method, and a photolithography method. A second electrode having a line pattern extending in a direction orthogonal to the line pattern and a passivation film can be sequentially stacked to form a light emitting portion.

(VII) Mirror (reflection film) (MIR)
The reflective film that can be used in the present invention is not particularly limited as long as it can efficiently reflect light from the organic EL layer toward the upper transparent electrode (second electrode). For example, those made of a metal or an alloy that reflects light can be mentioned. The reflective film provided on the transparent substrate is preferably an amorphous film having excellent flatness because it also serves as a base layer for the organic EL layer. Suitable metals and alloys for forming the amorphous film include CrB, CrP, or NiP.

  The reflective film can be provided on the upper surface or the back surface (back surface) of a transparent substrate such as glass or plastic. Moreover, you may provide the reflective film patterned according to the shape of the 1st electrode on a transparent substrate. Furthermore, instead of the transparent substrate, a substrate made of a metal or alloy that reflects light may be used via an insulating layer, so that the substrate and the reflective film may be used together. Parameters such as the thickness of the reflective film are conventional and can be appropriately selected by those skilled in the art. Note that when a conductive metal is used as the reflective film, an insulating thin film is formed on the reflective film. As the material for the insulating thin film, the inorganic oxide film, the inorganic nitride film, the organic material, or the like described above for the passivation film can be used.

  The reflective film can be formed by a conventional method such as a sputtering method, a CVD method, a vacuum deposition method, a dip method, or a sol-gel method. In addition, when an insulating thin film is formed on the reflective film as necessary, the thin film can be formed by a conventional means such as a sputtering method, a CVD method, a vacuum deposition method, a dip method, or a sol-gel method. .

  Next, the outer peripheral sealing layer, the sealing substrate, and the filler layer will be described. These are provided as necessary in order to maintain the airtightness of the organic EL display element of the present invention.

(VIII) Outer peripheral sealing layer The outer peripheral sealing layer is a support substrate provided with a color conversion filter layer, a light emitting part (first electrode, organic EL layer, second electrode) and the like, together with a sealing substrate, as an oxygen in the external environment. And has a function of protecting from moisture and the like. The outer peripheral sealing layer can be formed from, for example, an ultraviolet curable resin.

  When the alignment between the sealing substrate and the support substrate is completed, ultraviolet rays may be irradiated to cure the ultraviolet curable resin.

  Further, when an ultraviolet curable resin is used for the outer peripheral sealing layer, it can contain glass beads, silica beads, etc. having a diameter of 5 to 50 μm, preferably 5 to 20 μm. When these beads are bonded to the sealing substrate, they define a distance between the substrates (a distance between the substrate and the sealing substrate) and bear a pressure applied for adhesion.

  In addition, when encapsulating the filler in the internal space, a hole is provided in a part of the outer peripheral sealing layer, the outer peripheral sealing layer is cured, and the filler is injected from the hole, and then the hole is closed. .

(IX) Sealing Substrate The sealing substrate is not particularly limited as long as it seals the organic EL display element of the present invention and does not allow permeation of external moisture or harmful gas. Further, the film thickness and the like are also conventional. For example, a conventional sealing substrate can be used as it is.

(X) Filler Layer The filler layer is for filling the internal space in the organic EL display element and enhancing the hermeticity of the element.

  The filler for forming the filler layer may be an inert liquid or an inert gel that does not adversely affect the characteristics of the light emitting portion, the color conversion filter layer, and the like. The filler may be a liquid that gels after being injected into the internal space. Examples of this type of filler that can be used in the present invention include silicone resins, fluorinated inert liquids, fluorinated oils, and the like. The required amount of filler can be readily determined by one skilled in the art.

  In the organic EL display element of the present invention, the sealing substrate, the outer peripheral sealing layer, and the filler layer are uniformly coated with a resin such as an ultraviolet curable resin or a heat / light combination curable resin and cured. You may form integrally.

(XI) Insulating Film In the organic EL display element of the present invention, an insulating film can be disposed between the first electrode and the second electrode. In the present invention, the film can be formed particularly after the first electrode is formed. The light emitting portion of the element can be controlled by the insulating film, and power consumption can be suppressed. For example, when an insulating layer is not provided in a passive matrix type, light emission occurs not only on the side surface of the color conversion filter layer but also on the black matrix portion. The light emitted from this portion cannot reach the color conversion filter layer or the outside. Therefore, since it cannot be effectively used as an organic EL display element, the power consumption of the organic EL display element is increased. In order to reduce such loss, an insulating film is preferably formed around the subpixel.

  As a material for the insulating film, any material may be used as long as it has sufficient insulation resistance against the driving voltage of the light emitting portion and does not adversely affect the light emitting portion. For example, an inorganic oxide film or an inorganic nitride film can be used. Examples of such an inorganic oxide film or inorganic nitride film include silicon nitride, titanium oxide, tantalum oxide, and aluminum nitride. An insulating film formed using any of these materials can be manufactured by a dry method (such as a sputtering method, an evaporation method, or a CVD method). Photosensitive materials such as photoresist and novolac resin, and organic materials such as polyimide can also be used. A photoresist material can be used. An insulating film formed using any of these materials can be manufactured by a photolithography method or the like. The photolithography method is preferable because patterning is possible, and a minute shape can be easily processed.

  Parameters such as the thickness of the insulating film are conventional and can be appropriately selected by those skilled in the art. For example, the film thickness is 200 to 400 nm, preferably 250 to 350 nm.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the following embodiment, the color conversion filter substrate 30 and the light emitting unit 40 are bonded to each other with a gap GAP through a support (SUP1, SUP2). The color conversion filter substrate was prepared by forming a passivation film PL after patterning a color conversion filter layer EL made of red, green and blue dyes or pigments on a transparent substrate GL2 by photolithography. On the surface of the transparent substrate GL2 opposite to the color conversion filter layer, a right-angle conical array (for example, as shown in FIG. 2) or a conical array with a flattened top (for example, as shown in FIG. 4). Is formed). The light emitting part is obtained by forming the metal reflective film MIR on the transparent support substrate GL1 and then forming the organic EL layer EML.

Example 1
1. Production of transparent support substrate GL2 A quartz glass having a thickness of 0.7 mm is used, and a Cr film (thickness: 100 nm) patterned on the substrate at a predetermined pitch on one side is used as a mask, and C ₄ F ₈ and CH Finely processed by dry etching technology with a flow rate of ₂ F ₂ of 16 msccm and 16 sccm, a gas pressure of 0.8 Pa, and a power of 2 kW, respectively, a 1 μm-high conical array (pitch is 2 μm) Produced.

2. Production of Color Conversion Filter Layer A color conversion filter layer was formed by the following procedure on the transparent substrate GL2 on the side opposite to the surface having the right-angle conical array.
[Preparation of blue filter layer]
A blue filter material (manufactured by Fuji Film Arch Co., Ltd., color mosaic CB-7001) was applied by a spin coating method and patterned by a photolithographic method to obtain a blue filter layer.

[Production of green conversion filter layer]
Coumarin (0.7 parts by weight) as a fluorescent dye was dissolved in propylene glycol monoethyl acetate (PGMEA) (120 parts by weight) as a solvent. A photopolymerizable resin V259PA / P5 (trade name, Nippon Steel Chemical Industry Co., Ltd.) (100 parts by weight) was added thereto and dissolved to obtain a coating solution. This coating solution was applied on a transparent substrate on which a line pattern of the blue filter layer was formed using a spin coating method, and patterning was performed by a photolithographic method to obtain a green conversion filter layer.

[Production of red conversion filter layer]
Coumarin (0.6 parts by weight), rhodamine 6G (0.3 parts by weight) and basic violet 11 (0.3 parts by weight) as fluorescent dyes are dissolved in propylene glycol monoethyl acetate (PGMEA) (120 parts by weight) as a solvent. I let you. A photopolymerizable resin V259PA / P5 (trade name, Nippon Steel Chemical Industry Co., Ltd.) (100 parts by weight) was added thereto and dissolved to obtain a coating solution. This coating solution is applied on a transparent substrate on which a line pattern of a blue filter layer and a green conversion filter layer is formed using a spin coating method, and patterning is performed by a photolithographic method to obtain a red conversion filter layer. It was.

3. Production of Passivation Film A 300 nm-thickness SiOx film was formed at room temperature as a passivation film by DC sputtering. Si was used as the sputtering target, and a mixed gas of Ar and oxygen (Ar: oxygen = 5: 1) was used as the sputtering gas.

4). Production of Light-Emitting Section A bottom-gate TFT was formed on Corning glass as the transparent support substrate GL1, and the source of the TFT was connected to a metal reflective layer MIR made of Al. A planarizing insulating film (material: photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, resist or benzocyclobutene)) or a planarizing insulating film made of an inorganic material (coated silicon oxide film, PSG) (Including phosphorus-added glass), BPSG (glass added with boron and phosphorus), or a laminated film of these), and a contact hole is formed therethrough, through which Al Is formed on the planarization insulating film. As described above, the source of the TFT is connected to Al via a contact hole. IZO (InZnO) is formed on the upper surface of the Al as the anode of the organic EL layer. Note that Al is provided in order to reflect light emitted from the light emitting layer and efficiently extract light from the upper side of the organic EL display element, and to reduce electric resistance.

  The metal reflective layer, planarization insulating layer, Al layer, and IZO as the anode were formed by a conventional method such as sputtering.

  The film thickness of Al was 300 nm. The upper IZO has a high work function and is provided to inject holes efficiently. The thickness of IZO was 200 nm.

A hole injection layer, a hole transport layer, an organic light emitting layer, and an electron injection layer were sequentially formed on the IZO without breaking the vacuum in a resistance heating vapor deposition apparatus. During film formation, the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. 100 nm of copper phthalocyanine (CuPc) was laminated as a hole injection layer. As the hole transport layer, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was laminated to 20 nm. As an organic light emitting layer, 4,4′-bis (2,2′-diphenyl) biphenyl (DPVBi) was laminated to 30 nm. As an electron injection layer, 20 nm of Alq3 was laminated. Thereafter, a transparent electrode was formed without breaking the vacuum. A transparent electrode is formed by depositing a metal Mg / Ag having a small work function necessary for electron injection with a film thickness of 2 nm by a co-evaporation method, and depositing IZO with a film thickness of 200 nm by a sputtering method thereon. did.

5. Bonding The light-emitting part obtained as described above and the color conversion filter substrate are bonded together in a glove box using a UV curable adhesive in a dry nitrogen atmosphere (both oxygen and moisture concentrations are 10 ppm or less), and sealed. Stopped. The two substrates were not in contact except for the support (SUP1, SUP2) and sealing resin, and the sealing state was good.

(Evaluation)
When the luminance of the organic EL display element obtained as described above was evaluated, the luminance of the display element of the present invention was 60 to 80% as compared with the organic EL display element having no right-angle cone array structure. Improved.

(Example 2)
1. Production of Transparent Substrate GL2 A quartz glass having a thickness of 0.7 mm was used, and an SiO ₂ film having a thickness of 300 nm was formed on one surface thereof by a CVD method. Thereafter, a Cr film (film thickness: 100 nm) patterned on the substrate at a predetermined pitch is used as a mask, the flow rates of C ₄ F ₈ and CH ₂ F ₂ are 16 msccm and 16 sccm, respectively, and the gas pressure is 0.8 Pa, Fine processing was performed by a dry etching technique with a power of 2 kW, and a right conical array (pitch was 0.4 μm) having a height of 0.2 μm was produced.

  Other than this, an organic EL display element was produced in the same manner as in Example 1.

(Evaluation)
When the obtained organic EL display element was evaluated for luminance, the luminance of the display element of the present invention was improved by 50 to 60% as compared with the organic EL display element having no right-angle cone array structure.

(Example 3)
1. Production of transparent substrate GL2 A quartz glass having a thickness of 0.7 mm is used, and a Cr film (film thickness: 100 nm) patterned on the substrate at a predetermined pitch is used as a mask on one side thereof, and C ₄ F ₈ and CH ₂ F are used. The flow rate of ₂ is 16 msccm and 16 sccm, gas pressure is 0.8 Pa, power is 2 kW, and fine processing is performed by a dry etching technique, and a 1.0 μm-high conical array (pitch is 2 μm). And what cut | disconnected the top part in parallel with the bottom face by 0.2 micrometer was produced.

  Other than this, an organic EL display element was produced in the same manner as in Example 1.

(Evaluation)
When the luminance of the obtained organic EL display element was evaluated, the display element of the present invention was compared with the organic EL display element having no right-angled conical array structure with the top cut off as in this example. The brightness was improved by 30-50%.

  Compared with the organic EL display element produced in Example 1, the brightness is slightly lowered. In the present embodiment, this is probably because the top of the right-angled conical array is cut flat, so that total reflection occurs in this flat portion and the amount of extraction to the outside is reduced. If the top cut width is 0.3 μm or more, the improvement in luminance is about 25% or less as compared with an organic EL display element not having a right-angle conical array structure. Therefore, it is preferable that the cut width of the top portion of the right-angle cone-shaped protrusion is as small as possible, and the ratio is 0.2 or less of the height of the right-angle cone-shaped protrusion, desirably 0.1 or less.

It is a schematic sectional drawing of the conventional organic EL display element. (A) is a schematic sectional drawing of the organic electroluminescent display element of this invention, (b) is a top view of transparent substrate GL1, (c) is sectional drawing of transparent substrate GL1. It is a figure explaining the permeation | transmission of the light in the transparent substrate of the organic electroluminescent display element of this invention. (A) is a top view of transparent substrate GL1 of 2nd Embodiment, (b) is sectional drawing of the transparent substrate GL1, (c) is the light in the transparent substrate of the organic EL display element of this invention FIG. It is a figure which shows one Embodiment of the color conversion filter board | substrate of this invention.

Explanation of symbols

AIR External EY Viewer GL1 Support substrate GL2 Transparent substrate MIR Reflective film (mirror)
PL Passivation film EML Organic EL layer EL Color conversion filter layer LP Bright spot GAP Gap

Claims (6)

  A color conversion filter substrate including a support substrate, a light emitting unit including at least an organic EL layer having at least a first electrode, an organic light emitting layer, and a second electrode, a transparent substrate, a color conversion filter layer, and a passivation film An organic EL display element, wherein the transparent substrate is provided with a plurality of right-angle conical protrusions in an array on the surface opposite to the color conversion filter layer. Organic EL display element.   2. The organic EL display element according to claim 1, wherein the right cone-shaped protrusion is obtained by flattening a top portion of a right-angle cone shape.   The organic EL display element according to claim 1, wherein the transparent substrate is glass.   A color conversion filter substrate including at least a transparent substrate, a color conversion filter layer, and a passivation film, wherein the transparent substrate has a plurality of right-angle conical protrusions on a surface opposite to the color conversion filter layer. A color conversion filter substrate provided in an array.   The color conversion filter substrate according to claim 4, wherein the right cone-shaped protrusion is obtained by flattening a top portion of a right-angle cone shape.   6. The color conversion filter substrate according to claim 4, wherein the transparent substrate is glass.

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