JP2012160603A - Organic electroluminescence light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescence light emitting device capable of materializing planar white light at high efficiency and with low cost.SOLUTION: An organic electroluminescence element is formed in a band-shape by using a ribbon-shaped base material 10. On both sides in a width direction of an organic light emitting layer 2 of the element, auxiliary electrodes 5A and 5A for a reflection electrode 1 for reflecting side surface light emitted from a width direction end surface of the organic light emitting layer 2 toward a transparent electrode 3 side are provided. Transparent insulation layers 6L and 6R containing fluorescent material are arranged so as to cover the auxiliary electrodes 5A and 5A for the reflection electrode. Thereby, a small-sized module substrate M of a strip-shape is formed. A plurality of the small-sized module substrates M are disposed in a line on a large-sized mounting substrate so as to make edge portions in the width direction adjacent to each other, thereby increasing an area.

Description

  The present invention relates to an organic electroluminescence light emitting device in which a plurality of organic electroluminescence elements such as organic light emitting diodes are mounted side by side on a substrate.

  An electroluminescent element that provides a light-emitting layer between electrodes to obtain light emission is not only used as a light-emitting display device but also as a flat illumination, a light source for optical fibers, a backlight for a liquid crystal display, and a back for a liquid crystal projector. The use as a light source for various light emitting devices such as lights is also progressing. In particular, organic electroluminescence (hereinafter referred to as organic EL) elements using an organic thin film as a light emitting layer such as an organic light emitting diode (OLED) are attracting attention in terms of light emission efficiency, long life, light weight, and flexibility. Application to a planar (large area) planar light emitting device is under study.

  By the way, in a light emitting device for illumination such as a backlight, normally, white light whose light spectrum is widely distributed in the entire visible light region is used. As a method for obtaining such white light in an organic EL light emitting device, [1] a method of integrating elements (light emitting layers) that emit light in two colors (for example, blue and yellow) having a complementary color relationship on a substrate. [2] A method of arranging elements (light emitting layers) that emit light in the three primary colors red (R), green (G), and blue (B) side by side on a substrate, or [3] monochromatic light Using an element that emits (mainly blue), part of this monochromatic light is color-converted (wavelength-converted) using a fluorescent material, etc., and light of two colors (for example, blue and yellow) that are complementary colors Alternatively, a method of creating light of three primary colors (R, G, B) of light is known (see, for example, Patent Documents 1 and 2).

  In particular, the color conversion materials (CCM: Color Conversion Materials) using the wavelength of the light emitted from the monochromatic light emitting element [3] is not limited to the light emitting color (wavelength) of the element, and an organic EL element having higher luminance is used. Since it can be used as a light source, improvement in conversion (light emission) efficiency and color reproducibility is expected (see Patent Documents 3 and 4).

  On the other hand, as a technique for increasing the area of an organic EL light emitting device, a flat substrate such as a plate glass as a base material for stacking elements such as an LCD panel or a PD panel of a display device is enlarged (large format). And a method of integrating a large number of organic EL elements thereon is conceivable. However, increasing the size of the flat substrate increases the size of the vacuum equipment and the conveying device for processing the same, which increases capital investment. In addition, although accuracy as high as that of the panel of the display device is not required, even in the organic EL light emitting device, the quality varies between the central portion and the peripheral portion of a large substrate, or a part of the element on the substrate is defective. In other cases, the product inspection does not pass and the entire substrate is wasted.

  Therefore, as a method for increasing the area, a method is generally used in which light emitting elements are modularized and combined to increase the area. For example, a method is generally used in which a plurality of elements are arranged vertically and horizontally on a rectangular or rectangular small substrate, and this small substrate (module) is mounted side by side on a larger mounting substrate. ing.

  In addition, as a method for more efficiently forming a large area organic EL light-emitting device, for each color of R, G, B, using a long substrate such as a ribbon or tape (or fiber), A method of forming organic EL elements (substantially square or circular) on the substrate at predetermined intervals in the longitudinal direction and mounting the obtained long modules of respective colors on a large-sized mounting substrate in a predetermined order. Has been proposed (Patent Document 5).

JP 2004-63209 A Japanese Patent Laid-Open No. 2005-50552 JP 2003-243153 A JP-A-2005-71920 Japanese translation of PCT publication No. 2002-538502

  As described above, although the organic EL light emitting device that emits white light in a planar manner has been devised to increase the area, for further popularization, the manufacturing cost is reduced and energy is saved (low power consumption and low power consumption). Fever) is required. That is, the organic EL light-emitting device adopting the above configuration is currently capable of handling up to a certain size (width), but when considering application to a larger area such as a wall surface or outdoors, It is difficult to say that the manufacturing cost and luminance (luminous efficiency) per unit area have reached the level required by the user. There is room for improvement here.

  This invention is made | formed in view of such a situation, The objective is to provide the organic electroluminescent light-emitting device which can implement | achieve planar white light at high efficiency and low cost.

  In order to achieve the above object, an organic electroluminescence light-emitting device of the present invention comprises an organic electroluminescence element having an organic light-emitting layer sandwiched between a transparent electrode and a reflective electrode on a small module substrate, An organic electroluminescence light-emitting device that emits planar white light to the transparent electrode side by mounting a plurality of the module substrates side by side on a large mounting substrate, wherein the module substrate has a ribbon shape The organic electroluminescence element is formed in a strip shape along the longitudinal direction of the ribbon-shaped substrate, and at least the reflective electrode is formed wider than the organic light emitting layer. On the both sides in the width direction of the organic light emitting layer, side light emitted from the end surface in the width direction of the organic light emitting layer is transmitted to the transparent electrode side. A reflective electrode auxiliary electrode reflecting toward the width direction end of the reflective electrode is provided, and a transparent insulating layer containing a phosphor is formed so as to cover the reflective electrode auxiliary electrode. Take the configuration.

  That is, when the present inventor enlarges the size of an organic EL light emitting device that emits planar white light, the entire substrate is not wasted even if a partial failure occurs, and is efficiently manufactured at low cost. As a possible means, the idea was to produce a small module substrate in which color conversion type organic EL elements were laminated on a ribbon-like base material, and to mount this on a large substrate. In order to suppress an increase in power consumption of the organic EL light emitting device due to the increase in size, research has been conducted on whether there is a method for increasing the light emission efficiency (light extraction efficiency) of each module substrate. As a result, the inventor forms a strip-shaped small module substrate with the organic EL element as a band shape along the longitudinal direction of the ribbon-like base material, and absorbs side light leaking from the element on both sides in the width direction. Thus, it has been found that white light can be obtained with high luminous efficiency by providing a color conversion layer (transparent insulating layer containing a phosphor) that emits light having a wavelength that is complementary to the direct light of this element. Furthermore, the present inventor has devised the configuration of the strip-shaped module substrate so that the side light of the element is directed in the light emitting direction of the module substrate in the color conversion layers located on both sides of the band-shaped organic EL element in the width direction. It has been determined that the use efficiency of the side light can be further improved by providing the auxiliary electrode to be reflected, and the present invention has been achieved.

  As described above, in the organic EL light emitting device of the present invention, a small module substrate for mounting on a large mounting substrate is formed using a ribbon-like base material, and the organic electroluminescence element is It is formed in a strip shape along the longitudinal direction of the ribbon-shaped substrate, and at least the reflective electrode is formed wider than the organic light emitting layer, and side light of the organic light emitting layer is emitted on both sides of the organic light emitting layer in the width direction. A reflective electrode auxiliary electrode that reflects toward the transparent electrode is provided in contact with the widthwise end of the reflective electrode, and a transparent insulating layer containing a phosphor is formed so as to cover the reflective electrode auxiliary electrode. Has been. Therefore, the side light emitted from the end face in the width direction of the organic light emitting layer is reflected to the light emission side by the auxiliary electrode for the reflective electrode, and the light emitted from the module substrate together with the direct light emitted from the organic light emitting layer through the transparent electrode. Radiated towards the surface. Thereby, the light emission efficiency (light extraction efficiency) of the entire module substrate is improved. In addition, the side light reflected by the auxiliary electrode for the reflective electrode is partially (or most) provided by the transparent insulating layer containing the phosphor disposed so as to cover the auxiliary electrode for the reflective electrode. Color conversion (wavelength conversion) is performed to light having a predetermined wavelength that is a complementary color of the direct light. Thereby, the organic EL light-emitting device of this invention can obtain white light required for a backlight etc. with high luminous efficiency.

  In addition, this organic EL light emitting device has a simple structure and uses an expensive material compared to conventional organic EL light emitting devices using a large number of organic EL elements, color conversion layers, color filters, etc., in order to obtain white light. The module substrate can be efficiently manufactured using a roll-to-roll process. Therefore, the organic EL light emitting device of the present invention can be manufactured at low cost.

  In the organic EL light emitting device of the present invention, light emitted through the transparent electrode (direct light) and light emitted from the transparent insulating layers on both sides in the width direction (side light) are emitted to the emission side of the transparent electrode. Is provided with a light scattering layer for irregularly reflecting and mixing, uniform white light with little luminance unevenness and color unevenness between the part emitting direct light and the part emitting side light Can emit light.

It is typical sectional drawing which shows the structure of the module board used for the organic electroluminescent light emitting device of embodiment of this invention. It is a top view which shows the example which mounted the module board | substrate of embodiment of this invention on the large-sized mounting board | substrate. It is a typical sectional view showing other composition of the above-mentioned module substrate. It is a typical sectional view showing other composition of the above-mentioned module substrate.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a configuration of a module substrate used in the organic EL light emitting device of the embodiment of the present invention, and FIG. 2 shows a mounting example in which a plurality of the module substrates are arranged on a mounting substrate. It is a top view. The description will be made assuming that the front and back direction in FIG.

  The organic EL light-emitting device in the present embodiment is a light-emitting device used for a backlight such as a liquid crystal display, and an organic EL element is formed on a ribbon-like substrate 10 as shown in the cross-sectional view of FIG. As shown in the plan view of FIG. 2, the module boards M are arranged side by side on a large mounting board (not shown) so that the edges in the width direction are adjacent to each other. Connected (mounted).

  As shown in FIG. 1, the module substrate M is formed by using a long ribbon-shaped base material 10, and on the module substrate M, along the longitudinal direction of the ribbon-shaped base material 10 (front and back direction in the drawing). The organic light-emitting layer 2 and a strip-shaped organic EL element composed of the reflective electrode 1, the transparent electrode 3, and the like are laminated and cut in a predetermined length in the longitudinal direction (length L: see FIG. 2) As a strip-shaped module (width W: see FIG. 2). The reflective electrode 1 in the band-shaped organic EL element is formed wider than the organic light emitting layer 2, and the reflective electrode 1 is located outside the organic light emitting layer 2 in the width direction (the horizontal direction in the figure). The auxiliary electrodes 5A and 5A for the reflective electrode (1) having a substantially triangular cross section are provided at the end portions 1a and 1a in the width direction, and a phosphor is provided around the auxiliary electrodes 5A and 5A for the reflective electrode so as to cover the auxiliary electrodes 5A and 5A. The transparent insulating layers 6L and 6R to be contained are formed. This is a feature of the organic EL light emitting device in the present embodiment.

  The configuration of the module substrate M used in the organic EL light emitting device will be described in more detail together with the manufacturing method. The module substrate M is a top emission type module that emits white light toward a light emitting surface (upward in FIG. 1 and surface direction in FIG. 2) opposite to the ribbon-shaped substrate 10. A light scattering layer (light scattering plate 7) that diffuses and mixes light emitted from the organic EL element (open arrow) is disposed on the light emitting surface of the module substrate M (upper side in FIG. 1). Yes.

  The module substrate M is basically manufactured by a roll-to-roll process or an integrated vacuum process in order to reduce costs by increasing the efficiency of the manufacturing process. Therefore, as the ribbon-like substrate 10 for laminating the organic EL element, a long film-like or sheet-like flexible formed using a flexible material such as resin, metal foil, or ultrathin glass. A substrate is preferably used. In addition, as a typical dimension of the ribbon-shaped base material 10, the thing about 5-50 mm in width, 10-10000 m in length, and 10-500 micrometers in thickness is used.

  The reflective electrode 1 of the module substrate M is a light reflective (glossy) conductive film made of aluminum (Al), silver (Ag), or the like, and is a roll, It is formed continuously (in a band) by toe rolls. The production width of the reflective electrode 1 is formed so as to be wider in consideration of the width of the organic light emitting layer 2 described later. The reflective electrode 1 has a thickness (film thickness) of about 30 to 300 nm, more preferably 100 to 150 nm.

  The reflective electrode (1) auxiliary electrode 5A provided in contact with the widthwise ends 1a, 1a of the reflective electrode 1 is light-reflective made of aluminum (Al), silver (Ag), or the like, similar to the reflective electrode 1. And a conductive structure (protruding ridge in the longitudinal direction), which is connected to a positive electrode (+) of a power source or a control device (not shown) as shown in FIG. Power is evenly supplied in the longitudinal direction.

  The auxiliary electrode 5A for the reflective electrode is formed by laminating the auxiliary electrode material to a required thickness using an electron beam (EB) type or resistance heating type vacuum vapor deposition apparatus, and then etching by photolithography. 1 is formed in a reflective shape having a triangular cross section as shown in FIG. In addition, the width | variety of the said auxiliary electrode 5A for reflective electrodes is 100 micrometers-10 mm normally, Preferably they are 100 micrometers-2 mm, More preferably, they are 100 micrometers-1 mm. In addition to the triangular shape shown in FIG. 1, the cross-sectional shape of the reflective electrode auxiliary electrode (5A) is, for example, a semicircular cross-sectional protrusion as shown in the modification of FIG. 3 (reflective electrode auxiliary electrode 5B). ), Or a rib shape (reflecting electrode auxiliary electrode 5 </ b> C) having a square cross section as shown in the modification of FIG. 4, or a trapezoidal shape or other polygonal shapes.

  Further, the organic light emitting layer 2 of the module substrate M is generally a multilayer structure (not shown) in which an organic thin film (light emitting layer) and other layers that assist the movement of holes and electrons to the organic thin film are laminated. For example, a hole injection layer, a hole transport layer, an (electron blocking layer), etc. are disposed on the anode (in this embodiment, the reflective electrode 1) side with an organic thin film interposed therebetween, and a cathode (in this embodiment) On the transparent electrode 3) side, an electron transport layer, an electron injection layer, a (hole blocking layer) and the like are arranged. These layers are used in appropriate combinations according to the application and purpose. In the case of this embodiment, these layers are produced and formed by a continuous process (vacuum integrated process) using a vacuum deposition apparatus. The combined thickness of the organic light emitting layer 2 is several nm to several hundred nm.

  The light emitting material constituting the organic thin film (light emitting layer) of the organic light emitting layer 2 can be appropriately selected from various organic fluorescent materials such as dyes, metal complexes, and polymers. The light emitting material may be doped for the purpose of improving the light emission efficiency or changing the light emission wavelength. In the present embodiment, it is preferable to select a light emitting material that emits light from blue to blue green or a light emitting material that emits blue light from the viewpoint of the efficiency of color conversion.

  Luminescent materials (organic fluorescent substances) that can emit blue to blue-green light include fluorescent brighteners such as benzothiazole, benzimidazole, and benzoxazole, metal chelated oxinoid compounds, and styrylbenzene compounds. , A distyrylpyrazine derivative, or 1,4-phenylenedimethylidin, 4,4-phenylenedimethylidin, 4,4′-bis (2,2-di-t-butylphenylvinyl) biphenyl [DTBPBBi], And aromatic dimethylidin compounds such as 4,4′-bis (2,2-diphenylvinyl) biphenyl [DPVBi].

  As a light emitting material (organic fluorescent material) capable of obtaining blue light emission, bis (2-methyl-8-quinolinolate) (para-phenylphenolate) aluminum (III), bis (2-methyl-8) -Quinolinolato) (1-naphtholato) aluminum (III) and the like.

  Next, as the material of the transparent electrode 3 formed on the organic light emitting layer 2, a substance having sufficient transparency in the visible light region and having electrical conductivity necessary as an electrode can be used. Usually, indium oxide compounds such as indium tin oxide (ITO) and indium zinc oxide (IZO) are used. Other examples include tin oxide, tin oxide doped with antimony or fluorine, and zinc oxide doped with gallium. These may be used alone or in combination of two or more. Alternatively, the transparent electrode 3 may be formed by forming a thin metal electrode capable of maintaining translucency of several nanometers to several tens of nanometers from the interface of the organic light emitting layer 2 and forming ITO or the like thereon. In the present embodiment, as shown in FIG. 1, the transparent electrode (3) auxiliary electrode 4 for stably supplying a current to the transparent electrode 3 is provided on the transparent electrode 3. As shown in FIG. 2, the power supply and the negative electrode (−) of a control device (not shown) are connected.

  The transparent insulating layers 6L and 6R formed around the reflection electrode auxiliary electrodes 5A and 5A are formed of a composition in which a phosphor (fluorescent material) is dispersed in a binder resin. The transparent insulating layers 6L and 6R are formed using a coating method such as a spin coater or a bar coater by adding a solvent to a composition in which a phosphor is dispersed in a binder resin to obtain a resin composition solution (varnish). can do. The individual widths of the transparent insulating layers 6L and 6R are usually 200 μm to 20 mm, preferably 200 μm to 4 mm, and more preferably 200 μm to 2 mm. In addition to the coating method, it can be formed into a predetermined shape by patterning using an inkjet machine or photolithography, mask patterning using a vacuum deposition method, or the like.

  As the binder resin constituting the transparent insulating layers 6L and 6R, a thermosetting resin or a photocurable resin can be used. Specific examples of these include melamine resin in oligomer or polymer form, phenol resin, alkyd resin, epoxy resin, polyurethane resin, maleic acid resin, polyamide resin, or polymethyl methacrylate (PMMA), polyacrylate, Examples thereof include polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose and the like. These may be used alone or in combination of two or more. Further, as the photocurable resin, an acrylic acid or methacrylic acid photopolymerization type having a reactive vinyl group containing a photosensitizer, a photocrosslinking type such as polyvinyl cinnamate, or the like is used. Using these photo-curing resins, the transparent insulating layers 6L and 6R may be patterned (patterned) by photolithography.

  On the other hand, as the fluorescent material used for the transparent insulating layers 6L and 6R, various organic materials and inorganic materials are known. For example, as an organic fluorescent material that converts blue light into red light, cyanine dyes such as 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran, 1-ethyl-2 Examples include pyridine dyes such as-(4- (p-dimethylaminophenyl) -1,3-butadienyl) -pyridium-perchlorate, rhodamine dyes such as rhodamine B and rhodamine 6G, and oxazine dyes.

  Examples of organic fluorescent materials that convert blue light into green light include 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin, Coumarin dyes such as 3- (2′-benzothiazolyl) -7-diethylaminocoumarin, 3- (2′-benzimidazolyl) -7-N, N-diethylaminocoumarin, Coumarin dyes such as Basic Yellow 51, Solvent Yellow 11 , Naphthalimide dyes such as Solvent Yellow 116 and the like.

  Furthermore, as an organic fluorescent material that converts light emission from blue to green from orange to red (specifically, orange or yellow), for example, 4-dicyanomethylene-2-methyl-6- (p -Cyanine dyes such as dimethylaminostyryl) -4H-pyran (DCM), 1-ethyl-2- (4- (p-dimethylaminophenyl) -1,3-butadienyl) -pyridinium-perchlorate (pyridine 1 ) And other pyridine dyes, rhodamine B, rhodamine 6G and other rhodamine dyes, and oxazine dyes.

And as fluorescent material, inorganic fluorescent substance fine particles can also be used. Examples of the inorganic phosphor fine particles include metal oxides such as Y ₂ O ₃ , Gd ₂ O ₃ , ZnO, Y ₂ Al ₅ O ₁₂ , Zn ₂ SiO ₄ , Eu ²⁺ , u ³⁺ , Ce ³⁺ , Visible light such as Eu ²⁺ , Eu ³⁺ , Ce ³⁺ , Tb ^3+, etc. is doped into a metal chalcogenide such as ZnS, CdS, CdSe, etc. doped with transition metal ions that absorb visible light such as Tb ^3+. The thing doped with the transition metal ion to absorb can be mentioned.

  These fluorescent materials can be used alone or in combination of two or more. In addition, the transparent insulating layers 6L and 6R usually have a fluorescent material having the same composition in both (for example, when the organic light emitting layer 2 emits blue light, the blue light is converted into a complementary color yellow light. Fluorescent material) is used, but different transparent fluorescent materials may be used for the transparent insulating layer 6L and the transparent insulating layer 6R. In that case, for example, when the organic light emitting layer 2 emits blue light, a fluorescent material that converts blue light into red light is added to the transparent insulating layer 6L, and blue light is converted into green light into the transparent insulating layer 6R. If a fluorescent material is added, white light can be obtained by mixing these blue (B), red (R), and green (G) light.

  Next, the light scattering plate 7 disposed on the upper side (outgoing side) of the transparent electrode 3 and the transparent insulating layers 6L and 6R may be any transparent material such as a glass plate or a resin plate, and is colorless and transparent. In addition, a frosted glass-like material or a light scattering material having a different refractive index dispersed in a base material resin or the like may be used. Moreover, what was formed separately as the light-scattering board 7 may be bonded together, and you may form in the layer form using the apply | coating method etc. on the said transparent electrode 3 and the transparent insulating layers 6L and 6R. The light scattering plate 7 and the transparent electrode 3 are usually filled with an inert gas such as nitrogen or argon, a moisture absorbent called a getter material, or the like.

  As a base material constituting the light scattering plate 7, for example, acrylic resin, epoxy resin, silicon resin, polycarbonate resin, polyethylene terephthalate resin, fluorine-based resin, or the like can be used in addition to glass. The light scattering material may be any material that has low light absorption and a refractive index different from that of the base material. For example, silica, titanium, barium sulfate, calcium carbonate, or the like can be used. The amount of light scattering material added to the base material is appropriately set according to the haze value (cloudiness value) of the target light scattering plate 7. In addition, you may use what is marketed as a micro lens array film and a diffusion film for liquid crystal backlights, and the direction of the light radiate | emitted from the light-scattering plate 7 on the light-scattering plate 7 is made into the target direction. You may arrange | position a prism sheet, a light-condensing plate, etc. aligned in (illumination direction).

  The light scattering plate 7 may be individually formed on each of the strip-shaped module substrates M as shown in FIG. 1, but mounted side by side on a large mounting substrate as shown in FIG. After that, a large light scattering plate 7 (one piece) that covers the plurality of strip-like module substrates M at once may be provided. By using this large light scattering plate 7, unevenness (striped pattern) caused by the boundary (non-light emitting portion) between the strip-shaped module substrates M can be reduced.

  With these configurations, in the organic EL light emitting device of this embodiment, side light emitted from the end surface in the width direction of the organic light emitting layer 2 is extracted from the light emitting surface of the module substrate M, and apparently the entire module substrate M Luminous efficiency is improved. Further, a part (or most part) of the side light reflected by the auxiliary electrode for reflective electrode 5A passes through the transparent insulating layers 6L and 6R containing the phosphor, whereby the direct light of the organic light emitting layer 2 is emitted. It is possible to perform color conversion to light of a predetermined wavelength which is a complementary color of the above. Thereby, the organic EL light emitting device of the present embodiment can emit white light with high luminance and little color unevenness with high luminous efficiency.

  Moreover, since the organic EL light emitting device of this embodiment improves the light emission efficiency of each module substrate M as described above, it consumes less power (voltage) than a light emitting device using a conventional organic EL element. The same amount of light (brightness) can be obtained. Therefore, it is possible to save energy and extend the life of the organic EL light emitting device by driving at a low voltage.

  Furthermore, the organic EL light emitting device of the present embodiment uses the strip-shaped module substrate M that is long in the longitudinal direction, but on the reflective electrode 1 side, strip-shaped reflective electrode auxiliary electrodes 5A and 5A are provided along this. On the transparent electrode 3 side, strip-shaped auxiliary electrodes for transparent electrodes 4 and 4 are provided along the transparent electrode 3 side. For this reason, even if it is a low voltage drive as described above, a uniform current can be stably supplied to the strip-shaped organic light emitting layer 2 in the longitudinal direction. Therefore, in the organic EL light emitting device, even in the case of the long strip-shaped module substrate M, luminance unevenness and color unevenness do not occur in the longitudinal direction.

  And the organic EL light emitting device of this embodiment is wasted on the entire product (mounting substrate) even if a defect occurs in the module substrate M unit, like the organic EL light emitting device using a square or rectangular module. It has the advantage of not being.

  The ratio of the long side (longitudinal direction) to the short side (width direction) in the strip-shaped module substrate M (dimension ratio: see FIG. 2) is such that the length L of the long side is at least the length of the short side. It is desirable that the length is 5 times or more, preferably 10 times or more the length W of the short side. This is due to the following reason. That is, in the strip-shaped module substrate M, the length L of the long side is not less than 5 times the length W of the short side. Even when the area (projection area) of the upper light emitting surface of the organic EL element (organic light emitting layer 2) is the same, the length of the periphery (the entire circumference) of each organic EL element is longer than that of a circular one) Become. Therefore, the end face length (length of the side surface in the longitudinal direction) of the organic EL element formed on the ribbon-like substrate 10 is increased, and as a result, the area of the side end face that emits side light can be increased. . As a result, the module substrate M in which the length L of the long side is not less than 5 times the length W of the short side is such that the amount of light emitted from the top surface emitted toward the top surface is square or circular. Only the amount of side light emitted to the side surface of each element increases. Therefore, as described above, in the light emitting device using the strip-shaped module substrate M in which the length L of the long side is at least five times the length W of the short side, the side light from each module substrate M By increasing, the light extraction efficiency is further improved. By the way, of the total light energy emitted from the organic light emitting layer, the external light we see is about 25% of the total (internal waveguide light is about 40%), and about 35% of the total light energy is side light. Since there is a report that it disappears (deactivates) as described above, it is estimated that the effect of improving the luminous efficiency by the module shape is large.

  The ribbon substrate 10 of the module substrate M in the above embodiment includes polyethylene (PE), polypropylene (PP), post-styrene (PS), polycarbonate (PC), polyimide (PI), methacrylic resin (PMMA), polyethylene. Polymer base materials such as terephthalate (PET), polyethylene naphthalate (PEN), cycloolefin resin (COP), metal foil base materials such as stainless steel (SUS), aluminum (Al), copper (Cu), or ultra-thin glass A material having flexibility such as the above can be used. However, when the maximum roughness Rmax of the surface of the ribbon-shaped substrate 10 (surface on the organic EL element forming side) is 20 nm or more, a low outgassing material is applied by a wet method such as a slit coating method or a spray method. It is desirable to flatten the surface so that the maximum roughness Rmax of the surface is 20 nm or less.

  Examples of the hole transport layer constituting the organic light emitting layer 2 include phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, oxazoles, oxadiazoles, triazoles, imidazoles, imidazolones, stilbene derivatives, pyrazoline derivatives, tetrahydroimidazoles, polyaryls. Alkane, butadiene, 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), polyvinylcarbazole (PVK), polysilane, polyethylene dioxide thiophene (PEDOT) ), N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD), 4,4′-bis (N- ( Naphthyl) -N-phenyl-amino) biphenyl Or the like can be used (alpha-NPD) aromatic diamine compound such. Also, as the hole injection layer, it is possible to use copper phthalocyanine.

  Examples of the electron transport layer constituting the organic light emitting layer 2 include aluminum quinolinol complexes such as tris (8-quinolinol) aluminum complex (Alq3), 2- (4-biphenyl) -5- (pt-butyl). An oxadiazole derivative such as phenyl) -1,3,4-oxadiazole (ButylPBD), a triazole derivative, a triazine derivative, a phenylquinoxaline, or the like can be used. As the electron injection layer, alkali metals or alkaline earth metals such as Li, Ca, Cs, and Mg, or fluorides (such as LiF) or oxides of these metals can be used. In addition, as a film-forming method of each layer in the said organic light emitting layer 2, other than the continuous process (vacuum integrated process) using the vacuum evaporation apparatus mentioned above, for example, ionization vapor deposition method, MBE method, inkjet method etc. Can be used.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to the following examples.

Example 1
[Formation of reflective electrode]
As a ribbon-like substrate, a SUS304 foil (width 20 mm, length 100 m, thickness 50 μm) wound in a roll shape is prepared, and a liquid resist (phenol novolac resin system: Nippon Zeon) is used to flatten the surface. ZWD6216-6) manufactured by the company was applied by a spin coat method and dried to form a smoothing layer (film thickness: 3 μm). And on this smoothing layer, using a sputtering device, a reflective electrode made of a silver alloy (APC-TR, silver alloy containing palladium and copper, manufactured by Furuya Metal Co., Ltd.) by roll-to-roll ( A film having a width of 20 mm and a thickness of 100 nm was formed. In addition, the width of the reflective electrode is designed to be wider than an organic light emitting layer (width 18 mm) to be manufactured later.

[Formation of auxiliary electrode for reflective electrode]
Next, an Al thin film (thickness: 1000 μm) is formed on the entire surface of the ribbon-like substrate by electron beam (EB) vapor deposition or resistance heating vapor deposition so as to cover the reflective electrode, and a photosensitive resist is formed on the Al thin film. Is applied, mask exposure and development are performed, unnecessary portions of the thin film are removed by etching, and a triangular cross section (base width 1 mm, height 1 mm) is formed on both sides of the reflective electrode in the width direction (near the end). A reflective electrode auxiliary electrode was formed (see FIG. 1).

[Formation of transparent insulating layer]
As a material for the transparent insulating layer (wavelength conversion layer), a phosphor having an emission wavelength (435 to 440 nm) from the organic light emitting layer and an excitation wavelength coincident with each other: (E) -2- (2- (4- (dimethylamino)) (styryl) -6-methyl-4H-pyran-4-ylidene) malonitrite (DCM OHJEC) 5 wt% and binder resin: methyl methacrylate [PMMA] 100 wt%, 200 ml of tetrahydrofuran [THF Wako Pure Chemical Industries, Ltd. A varnish dispersed and dissolved in Kogyo Co., Ltd. was prepared.

  Next, the prepared transparent insulating layer material (varnish) was applied to the entire surface of the ribbon-like substrate so as to cover the reflective electrode and the auxiliary electrode for reflective electrode by spin coating, and post-baked (220 ° C. × 60 And a transparent insulating layer having a thickness (height from the upper surface of the ribbon-like substrate) of 100 nm was formed. Thereafter, a photosensitive resist [JEN-477 manufactured by JSR Co., Ltd.] is applied onto the transparent insulating layer, mask exposure and development are performed, unnecessary portions of the insulating layer are removed by etching, and a transparent insulating layer having a required pattern is obtained. Was made. The width of each transparent insulating layer obtained (width from the edge in the width direction of the ribbon-like substrate) was 4 mm (height 100 nm).

[Formation of organic light-emitting layer]
Next, the ribbon-like base material on which the transparent insulating layer is formed is set in a vacuum vapor deposition machine, and on a reflective electrode (exposed surface) between the transparent insulating layers, under vacuum, roll-to-roll, Each material was continuously formed in the following order (the film thickness is individually displayed) to form an organic light emitting layer.
1) As a hole transport layer, polyvinylcarbazole (manufactured by PVK Aldrich) 30 nm
2) As a light emitting layer, 4,4′-bis (N- (naphthyl) -N-phenyl-amino) biphenyl [manufactured by α-NPD OHJEC] 30 nm
3) As a hole blocking layer, 2- (4-biphenyl) -5- (pt-butylphenyl) -1,3,4-oxadiazole [Butyl PBD OHJEC Co., Ltd.] 30 nm
4) As an electron transport layer, tris (8-quinolinol) aluminum complex [Alq3 OHJEC Co.] 20 nm
5) As an electron injection layer, lithium fluoride [LiF Furuya Metal Co., Ltd.] 0.5 nm

[Formation of transparent electrode]
Subsequently, using the same vacuum evaporation machine, on the organic light emitting layer,
6) Aluminum [Al] 15 nm as a semi-transmissive metal electrode
Was deposited. Next, the ribbon-like base material on which the transflective metal electrode is formed is set in a sputtering apparatus, and a transparent electrode (width 20 mm, thickness) made of indium tin oxide [ITO] is roll-to-rolled under vacuum. 100 μm) was formed.

[Formation of auxiliary electrode for transparent electrode]
Finally, a metal thin film such as Al or Ag having a low electric resistance value was formed by sputtering so as to cover both sides in the width direction (near the end) of the transparent electrode through a shadow mask. The transparent electrode auxiliary electrodes on both sides in the width direction had a width of 0.1 mm and a thickness of 100 μm, respectively (see FIG. 1).

  Unlike the above-described embodiment, the light scattering layer (light scattering plate) disposed on the organic EL element is not attached at this stage, and after mounting a plurality of module substrates on a mounting substrate described later, the plurality of these A large light scattering layer that covers all of the module substrates at once is attached. Further, the module substrate (still in a “long ribbon shape”) formed up to the transparent electrode auxiliary electrode is taken out into the atmosphere and cut into 100 mm lengths, and the width (W) 20 mm × length A large number of strip-shaped module substrates (L / W = 5) having a length (L) of 100 mm were produced.

[Mounting the module board]
On the prepared large mounting substrate, using the five strip-shaped module substrates having a width of 20 mm and a length of 100 mm, they are arranged side by side so that the edges in the width direction are adjacent to each other. Were electrically connected (mounted) (see FIG. 2). A light scattering layer (light-scattering film made of alicyclic resin: D114 series, manufactured by Tsujiden Co., Ltd., thickness 10 μm) covering these five strip-shaped module substrates is attached to the organic EL panel of Example 1. A light emitting device was obtained.

(Comparative Example 1)
The module substrate and organic EL of Comparative Example 1 were the same as in Example 1 except that DCM was not added to the material (varnish) for forming the transparent insulating layer in “Transparent insulating layer formation” above. A light emitting device was manufactured.

(Comparative Example 2)
A module substrate and an organic EL light-emitting device of Comparative Example 2 were produced in the same manner as in Example 1 except that no “light scattering layer” was disposed on the module substrate in “Mounting of Module Board”.

The obtained organic EL light emitting devices of Example 1 and Comparative Examples 1 and 2 were connected to a power source to emit light, and “chromaticity (CIE color) of emitted light emitted to the front surface (upper light emitting surface) of these organic EL light emitting devices. Degree) ”and“ luminescence intensity (luminance) ”were compared. The results are shown below.
<Measurement conditions> A current of 9 V and 60 mA was applied between the anode (reflecting electrode) and the cathode (transparent electrode) of the sample at room temperature.
<Chromaticity and Luminance Measuring Device> Organic EL Luminous Efficiency Measuring Device EL1003 manufactured by Presize Gauge
Distance between measurement probe and sample: 200mm

  Note that the CIE chromaticity is represented by (x, y) and represents a coordinate (xy orthogonal coordinate) position on the chromaticity diagram. Incidentally, in the television for broadcasting reception (light emitting cathode ray tube), white (W) is (0.310, 0.316) and blue (B) is (0. 0) according to the NTSC (National Television Broadcast Standardization Committee) standard. 14, 0.08), green (G) is defined as (0.21, 0.71), and red (R) is defined as (0.67, 0.33).

In addition, as a luminance of the light emitting device, in recent years, as a large screen type liquid crystal display device (LCD) for outdoor use, the luminance of the built-in backlight is 1700 to 2000 cd / m ² and the contrast ratio is about 500 to 1000: 1. Things are commercially available.

[Measurement results of chromaticity and brightness]
Example 1: CIE chromaticity = (0.35, 0.30) white Luminance = 2200 cd / m ²
Comparative Example 1: CIE chromaticity = (0.16, 0.09) blue luminance = 846 cd / m ²
Comparative Example 2: CIE chromaticity = (0.35, 0.26) slightly bluish luminance = 3142 cd / m ²

<Evaluation>
Compared to Example 1, the organic EL light emitting device of Comparative Example 1 which was not color-converted had low luminance and only blue light emission was obtained. Thereby, the improvement of the brightness | luminance by color conversion was confirmed. Moreover, although the organic EL light emitting device of Comparative Example 2 in which no light scattering layer is provided with respect to Example 1 has high luminance, the non-light emitting portion between each module substrate becomes a black striped pattern and looks good Is bad. Thereby, the effect of the light scattering plate was confirmed. Compared to Comparative Examples 1 and 2, it was found that the organic EL light emitting device of Example 1 can obtain natural white light with high luminance and is suitable for an illumination device such as a backlight.

  The organic electroluminescence light emitting device of the present invention has a low manufacturing cost per module and can emit uniform white light with high efficiency. Therefore, it is suitable for a large-area light emitting device such as a backlight.

DESCRIPTION OF SYMBOLS 1 Reflective electrode 2 Organic light emitting layer 3 Transparent electrode 5A Auxiliary electrode 6L, 6R Transparent insulating layer 10 Base material M Module substrate

Claims (2)

  An organic electroluminescence element having an organic light emitting layer sandwiched between a transparent electrode and a reflective electrode is formed on a small module substrate, and a plurality of the module substrates are mounted side by side on a large mounting substrate. Thus, an organic electroluminescence light emitting device that emits planar white light to the transparent electrode side, wherein the module substrate is formed using a ribbon-like base material, and the organic electroluminescence element is the ribbon Formed in a strip shape along the longitudinal direction of the substrate, at least the reflective electrode is formed wider than the organic light emitting layer, and the width of the organic light emitting layer is provided on both sides of the organic light emitting layer in the width direction. A reflective electrode auxiliary electrode that reflects side light emitted from the direction end face toward the transparent electrode is provided in contact with the width direction end of the reflective electrode. It is, so as to cover the reflective electrode auxiliary electrode, an organic electroluminescent light emitting device and a transparent insulating layer containing a phosphor is formed.   2. A light scattering layer is provided on the emission side of the transparent electrode to diffusely reflect and mix light emitted through the transparent electrode and light emitted from the transparent insulating layers on both sides in the width direction. The organic electroluminescence light-emitting device described.

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