JP2009289460A - Surface-emitting light source using organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-emitting light source, capable of efficiently obtaining surface light emission with a uniform emission intensity distribution, even if an ITO is not used as an electrode material. <P>SOLUTION: Of the surface-emitting light source using a surface-emitting light source organic electroluminescent element, the organic electroluminescent element is provided with an anode, a cathode and an organic light-emitting layer pinched by the anode and the cathode. The anode and the cathode are formed of metal or an alloy, opaque having light reflexivity, either of them formed in a uniform planar shape, and the other formed in intervals so as to have a plurality of light-extracting parts. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface-emitting light source using an organic electroluminescent element. More specifically, the present invention relates to a surface emitting light source using an organic electroluminescent element (hereinafter also referred to as “organic EL element”) that emits light by applying a voltage to an organic light emitting layer sandwiched between an anode and a cathode. About.

  Since the organic EL element has an advantage that a surface emitting light source having high luminous efficiency can be manufactured at low cost, in recent years, a light source for an illumination device or a liquid crystal display device using the organic EL element has been actively developed. In an organic EL element, generally, an anode, a single layer or a plurality of layers of an organic light emitting layer including an organic light emitting layer and a cathode are laminated on a flat substrate. In order to take out light emitted from the organic light emitting layer, the anode and At least one of the cathodes is formed of a transparent material.

  Indium tin oxide (hereinafter also referred to as “ITO”) is widely used as a transparent electrode material. However, since the electrical resistance of ITO is much higher than that of a conductive material such as a metal, the emission intensity distribution on the light emitting surface becomes non-uniform due to the problem that the organic EL element deteriorates due to heat generated by energization and the voltage drop. There is also a problem. Such a problem is particularly serious in a surface emitting light source having a large area of ITO, and various improvements have been made so far.

  For example, Patent Literature 1 discloses a lighting device in which an organic EL element is formed on a heat dissipation plate and a heat conductive elastic member. Here, an attempt is made to suppress the deterioration of the element due to heat and make the light emission intensity distribution uniform by providing a heat radiating plate and a heat conductive elastic member.

Patent Document 2 discloses a transparent electrode formed on a transparent substrate, an organic light emitting layer formed on the transparent electrode, and a metal formed on the transparent electrode at a certain distance from the organic light emitting layer. An organic EL element having an auxiliary electrode and a cathode formed on the organic light emitting layer is disclosed. Here, an attempt is made to reduce the problem of heat generation and voltage drop and to make the emission intensity distribution uniform by forming an auxiliary electrode.
JP 2006-324199 A JP 2003-45674 A

  However, as long as ITO is used as the electrode material, it is difficult to essentially solve the problems of element degradation and uneven emission intensity distribution due to heat generation and voltage drop, which are described in Patent Documents 1 and 2. The technology has room for improvement.

  On the other hand, when a metal having a low electrical resistance is used as the electrode material, the formed electrode is opaque, so that there is a problem that light emitted from the organic light emitting layer cannot be extracted from the electrode surface. In addition, when the said electrode is used as a very thin film and transparency is ensured, since an electrical resistance becomes high, the said problem cannot be solved.

  Accordingly, an object of the present invention is to provide an organic EL element that can efficiently obtain surface light emission having a uniform light emission intensity distribution.

  As a result of intensive studies to solve the above problems, the present inventors have developed an organic EL device structure that can efficiently obtain surface light emission having a uniform light emission intensity distribution even when an opaque metal or the like is used as an electrode material. The headline and the present invention were completed.

That is, the present invention relates to the following (1) to (15).
(1) A surface-emitting light source using an organic electroluminescent element,
The organic electroluminescent element has an anode, a cathode, and an organic light emitting layer sandwiched between the anode and the cathode,
The anode and the cathode are formed of an opaque metal or alloy having light reflectivity,
One of the anode and the cathode is formed in a uniform surface, and the other is formed in an intermittent manner so as to have a plurality of light emission extraction portions.

(2) The cathode is formed in a uniform plane, the anode is formed in a plurality of strips,
The surface emitting light source according to (1), wherein the light emission extraction portion is formed between a plurality of strip-like anodes.

(3) The cathode is formed in a uniform plane, the anode is formed in a plane having a plurality of pores,
The surface emitting light source according to (1), wherein the light emission extraction portion is formed by a plurality of pores.

(4) The organic electroluminescent device further includes an absorption layer made of a material that absorbs at least part of the light emitted from the organic light emitting layer and emits light having a wavelength different from the absorbed light. ,
The surface-emitting light source according to (2) or (3), wherein the absorption layer is formed in the light emission extraction portion.

(5) The surface emitting light source according to (2), wherein the cathode is formed so as to cover an outer edge of the organic light emitting layer.
(6) The organic electroluminescent device further includes a transparent substrate,
The surface emitting light source according to (5) above, wherein the anode is formed on the transparent substrate.

(7) Furthermore, a through hole is formed in the substrate so as to correspond to at least a part of the anode formed on the transparent substrate,
On the surface opposite to the surface on which the anode is formed on the substrate, a connecting portion for connecting the anode and the power source is formed,
The surface emitting light source according to (6) above, wherein the anode is connected to the connecting portion through the through hole.

(8) The anode is formed in a uniform plane, and the cathode is formed in a plurality of strips,
The surface emitting light source according to (1), wherein the light emission extraction portion is formed between a plurality of strip-like cathodes.

(9) The anode is formed in a uniform plane, and the cathode is formed in a plane having a plurality of pores.
The surface emitting light source according to (1), wherein the light emission extraction portion is formed by a plurality of pores.

(10) The organic electroluminescent device further includes an absorption layer made of a material that absorbs at least part of the light emitted from the organic light emitting layer and emits light having a wavelength different from the absorbed light. ,
The surface-emitting light source according to (8) or (9), wherein the absorption layer is formed in the light emission extraction portion.

(11) The surface-emitting light source according to (8), wherein the anode is formed so as to cover an outer edge of the organic light-emitting layer.
(12) The organic electroluminescent element further has a transparent substrate,
The surface emitting light source according to (11), wherein the cathode is formed on the transparent substrate.

(13) Furthermore, a through hole is formed in the substrate so as to correspond to at least a part of the cathode formed on the transparent substrate,
On the surface opposite to the surface on which the cathode is formed on the substrate, a connection portion for connecting the cathode and the power source is formed,
The surface emitting light source according to (12), wherein the cathode is connected to the connecting portion through the through hole.

(14) The surface-emitting light source as described in (8) or (9) above, wherein the anode also serves as a support for an organic electroluminescent element.
(15) The surface-emitting light source according to any one of (1) to (14), wherein the organic light-emitting layer is formed from a solution containing a polymer material.

  (16) The surface emitting device as described in (15) above, which includes a step of applying a solution containing the polymer material and heating the glass material to a glass transition temperature or higher to form an organic light emitting layer. Manufacturing method of light source.

  (17) A white illumination device using the surface-emitting light source according to any one of (1) to (15).

  According to the surface emitting light source of the present invention, surface emission having a uniform light emission intensity distribution can be efficiently obtained without using ITO as an electrode material.

  The surface-emitting light source of the present invention is a surface-emitting light source using an organic electroluminescent element, and the organic electroluminescent element has an anode, a cathode, and an organic light-emitting layer sandwiched between the anode and the cathode. The anode and the cathode are formed of an opaque metal or alloy having light reflectivity, and one of the anode and the cathode is formed in a uniform plane, and the other has a plurality of light emission extraction portions. It is characterized by being formed intermittently. Hereinafter, embodiments of the present invention will be described in detail.

<Embodiment 1>
About the surface emitting light source which concerns on Embodiment 1 of this invention, FIG. 1-1 shows a perspective view, FIG. 1-2 shows sectional drawing cut | disconnected along AB of FIGS. 1-1. In the surface-emitting light source of Embodiment 1, the organic electroluminescent element has a transparent substrate 102, an anode 104, a cathode 106, and an organic light-emitting layer 108 sandwiched between the anode 104 and the cathode 106, and the anode 104 is transparent. It is formed on the substrate 102. In addition, the anode 104 is formed in a plurality of strips (five strips in FIGS. 1-1 and 1-2), and the cathode 106 is formed in a uniform plane, and between the plurality of strips of anodes 104, A light emission extraction portion 110 is formed. The anode 104 and the power source are connected by the surface (connection portion 112) of the anode 104 where the organic light emitting layer 108 is not formed.

  Here, in the surface-emitting light source of Embodiment 1, a path through which light emitted from the organic light-emitting layer 108 is taken out will be described with reference to FIGS. The portion that emits light by applying voltage in the organic light emitting layer 108 is a portion sandwiched between the anode 104 and the cathode 106 (portion A surrounded by a dotted line in FIG. 1-5). The light emitted from the point B in the portion A travels in all directions. However, since the anode 104 and the cathode 106 are made of an opaque metal or alloy having light reflectivity, the anode 104 and the cathode 106 are repeatedly reflected. While repeating this reflection, the light is extracted from the light emission extraction portion 110 (the gap between the anode 104 and the anode 104) through the substrate 102 (arrow in FIG. 1-5). That is, the light emitted from the organic light emitting layer 108 is taken out through the substrate 102 only from the anode 104 side.

  Thus, in the surface emitting light source according to the first embodiment, by providing the light emission extraction unit 110, light emission can be efficiently extracted even when an opaque metal or alloy is used as the electrode material. In addition, since a metal or alloy having excellent thermal conductivity and electrical conductivity is used, heat generation and voltage drop can be suppressed unlike using ITO. As a result, the organic EL element hardly deteriorates and the light emission intensity distribution becomes uniform.

  The material of the transparent substrate 102 is not particularly limited as long as it has transparency and electrical insulation, and examples thereof include transparent materials such as glass, PET (polyethylene terephthalate), and polycarbonate.

  The anode 104 is formed in a strip shape on the substrate 102 as shown in FIG. Thereby, the light emission extraction part 110 is formed between the anodes 104. FIG. 1-3 is a diagram illustrating a stage in which the anode 104 is formed on the substrate 102 when the surface-emitting light source of Embodiment 1 is manufactured. The anode 104 is formed of an opaque metal or alloy having high light reflectivity and excellent electrical conductivity and thermal conductivity. Examples of such an anode material include Al, Cr, In, Sn, Ta, Ti, V, W, Zn, Zr, Hf, Mo, Nb, Cd, Cu, Pb, Ag, Au, Pt, Pd, and Ni. And alloys thereof. Among them, Al, Cr, Ni, Ag, Pd, Pt and alloys of these metals and W are preferable because of high light reflectance and excellent smoothness.

  The width of the anode 104 is preferably narrow enough not to impair the conductivity of the anode 104, and specifically, it is desirably in the range of 0.1 to 1000 μm. Furthermore, if the width of the anode 104 is within this range, the light emission of the organic EL element can be visually recognized as a surface light source. The thickness of the anode 104 is preferably thick enough to exhibit high light reflectivity and conductivity, specifically 0.05 to 1000 μm, more preferably 0.1 to 100 μm. . The width of the light emission extraction part 110 (the interval between the anode 104 and the adjacent anode 104) is preferably within a range in which light emitted from the organic light emitting layer 108 can be extracted more efficiently and the light emission intensity distribution on the light emitting surface becomes smaller. Specifically, it is desirable to be in the range of 1 to 10,000 μm, more preferably 1 to 5000 μm.

In addition, for the purpose of improving hole injection into the organic light emitting layer 108, the surface of the anode 104 is made of SiO _2.
And a conductive polymer such as metal oxide such as MoO ₃ , fluorocarbon and polypyrrole, and may be coated with a layer of usually 0.1 to 30 nm, preferably 0.1 to 10 nm.

As a method for forming an electrode material, a resistance heating vapor deposition method, an electron beam vapor deposition method, a dry vapor deposition method such as a sputtering method or an ion plating method, or a coating method in which a dispersion liquid containing metal colloid particles is wet coated is used. It is done. In order to form the anode 104 in a strip shape, the electrode material may be formed by masking a portion where the anode 104 is not formed in the dry deposition method and the coating method. Also, in the coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, spray coating method, screen printing method, flexographic printing method, offset printing. Application patterning may be performed only at a predetermined position by a method, an ink jet printing method, or the like. Further, patterning may be removed after film formation on the entire surface. In patterning removal, known patterning methods such as a photolithography method and an imprint method including a wet etching method and a dry etching method can be used in combination.

  The organic light emitting layer 108 is uniformly formed on the upper surface of all the anodes 104 and the portion sandwiched between the anodes 104 (light emission extraction portion 110) as shown in FIG. 1-4 is a diagram showing a stage in which the organic light emitting layer 108 is formed on the substrate 102 and the anode 104 when the surface emitting light source of Embodiment 1 is manufactured. Here, the organic light emitting layer 108 is formed on the surface of the anode 104 except for the connection portion 112 with the power source. The organic light emitting layer 108 is made of a known material. Examples of such materials include phosphorescent transition metal complexes and phosphorescent polymers. More specifically, examples of the phosphorescent transition metal complex include a palladium complex, an osmium complex, an iridium complex, a platinum complex, and a gold complex. The phosphorescent polymer can be obtained, for example, by copolymerizing a phosphorescent transition metal complex having a polymerizable substituent and, if necessary, a carrier transporting compound having a polymerizable substituent. .

  As a method for forming the organic light emitting layer 108, a resistance heating vapor deposition method, an electron beam vapor deposition method, a dry film forming method such as a sputtering method, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, Examples of the coating film forming method include a roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, and an inkjet printing method. In the case where a phosphorescent polymer is used, it is more preferable to form a film by coating a solution containing the polymer material. In addition, it is particularly preferable to apply a solution containing a polymer material and form the organic light-emitting layer 108 by heating to a temperature higher than the glass transition temperature of the polymer material after application because the surface of the organic light-emitting layer 108 can be planarized.

  The cathode 106 is uniformly formed so as to cover the entire upper surface of the organic light emitting layer 108 as shown in FIGS. 1-1 and 1-2. The cathode 106 is made of an opaque metal or alloy having high light reflectivity and excellent electrical conductivity and thermal conductivity. As such a cathode material, a material having a small work function is preferable in order to efficiently inject electrons into the organic light emitting layer 108. For example, alkali metals such as Li, Na, K, and Cs, Mg, Ca, Ba, and the like are preferable. Alkali earth metals, Al, MgAg alloys, AlLi, AlCa and other alloys of Al and alkali metals or alkaline earth metals. Alternatively, the cathode 106 may be formed by stacking these metals or alloys.

  The thickness of the cathode 106 is preferably thick enough to exhibit high light reflectivity and conductivity, specifically 0.05 to 1000 μm, more preferably 0.1 to 100 μm. .

  As a method for forming an electrode material, a resistance heating vapor deposition method, an electron beam vapor deposition method, a dry vapor deposition method such as a sputtering method or an ion plating method, or a coating method in which a dispersion liquid containing metal colloid particles is wet coated is used. It is done.

In FIGS. 1-1 and 1-2, the organic light emitting layer 108 is uniformly formed on the upper surface of all the anodes 104 and a portion (light emission extraction portion 110) sandwiched between the anodes 104 ( In the first embodiment, the surface of the anode 104, excluding the connection portion 112 with the power source), is not limited to this. For example, it may be uniformly formed on the upper surface of a part of the anode 104 and a part of the part sandwiched between the anodes 104 (light emission extraction part 110). 1-1 and 1-2, the cathode 106 is uniformly formed so as to cover the entire upper surface of the organic light emitting layer 108 so that light emitted from the organic light emitting layer 108 does not leak from the cathode 106 side. ing. However, in Embodiment 1, as long as it forms so that it may straddle on the some anode 104, it is not restricted to this. In addition, for the purpose of dividing the light emitting region into several, a plurality of cathodes 106 may be formed on one organic light emitting layer 108 as described in, for example, Japanese Patent No. 3918558.

<Embodiment 2>
About the surface emitting light source which concerns on Embodiment 2 of this invention, FIGS. 2-1 shows a perspective view, FIG. 2-2 shows sectional drawing cut | disconnected along AB of FIGS. 2-1. In the surface-emitting light source of Embodiment 2, the organic electroluminescent element has a transparent substrate 102, an anode 104, a cathode 106, and an organic light-emitting layer 108 sandwiched between the anode 104 and the cathode 106, as in Embodiment 1. The anode 104 is formed on the transparent substrate 102. Further, the anode 104 is formed in a plurality of strips (five strips in FIGS. 2-1 and 2-2), and a light emission extraction portion 110 is formed between the plurality of strips of anodes 104. Note that the anode 104 and the power source are connected by a connecting portion 112.

  In the second embodiment, unlike the first embodiment, the cathode 106 is formed in a uniform plane and is formed so as to cover the outer edge of the organic light emitting layer 108. That is, the cathode 106 is formed so as to uniformly cover the upper surface and the side surface (the side surface parallel to the longitudinal direction of the anode 104 and the connection portion 112 is not formed) of the organic light emitting layer 108. The cathode 106 is formed so as to be in contact with the substrate 102 on the side surface of the organic light emitting layer 108.

  As described above, in the surface emitting light source according to the second embodiment, the cathode 106 covers the outer edge of the organic light emitting layer 108 so that light does not leak out from the outer edge of the organic light emitting layer 108. Therefore, light emission can be extracted from the anode 104 side more efficiently.

  In order to manufacture the cathode 106 in the form as described above, first, a light emitting layer is formed so as to have an area smaller than the upper surface of the substrate, leaving the outer edge portion of the substrate, and subsequently the same method as in the first embodiment. A cathode having a larger area than the light emitting layer is formed.

  In the second embodiment, the anode 104 and the power source are connected by the connection unit 112, but the present invention is not limited to this. For example, a through hole 202 is formed in the substrate 102 so as to correspond to at least a part of the anode 104 formed on the transparent substrate 102, and is opposite to the surface on which the anode 104 is formed on the substrate 102. A connecting portion 204 for connecting the anode 104 and the power source may be formed on the side surface (see FIG. 2-3). In this case, the anode 104 is connected to the connecting portion 204 through the through hole 202. In this aspect, as described above, since all the emitted light emitted from the side surface of the light emitting layer can be reflected, the emitted light can be extracted from the light emitting surface more efficiently.

<Embodiment 3>
About the surface emitting light source which concerns on Embodiment 3 of this invention, FIGS. 3-1 shows a perspective view, FIG. 3-2 shows sectional drawing cut | disconnected along AB of FIGS. 3-1. In the surface-emitting light source of Embodiment 3, the organic electroluminescent element has a transparent substrate 102, an anode 104, a cathode 106, and an organic light-emitting layer 108 sandwiched between the anode 104 and the cathode 106, as in Embodiment 1. The anode 104 is formed on the transparent substrate 102. The cathode 106 is formed in a uniform plane. The anode 104 and the power source are connected by the surface (connection portion 112) of the anode 104 where the organic light emitting layer 108 is not formed.

  In the third embodiment, unlike the first embodiment, the anode 104 is formed in a planar shape having a plurality of pores (square holes), and the light emission extraction portion 110 is formed by a plurality of pores (FIG. 3). -3). FIG. 3C is a diagram illustrating a stage in which the anode 104 is formed on the substrate 102 when the surface-emitting light source according to the third embodiment is manufactured.

  In the surface-emitting light source of Embodiment 3, the light emitted from the organic light-emitting layer 108 is repeatedly reflected by the anode 104 and the cathode 106, and then passes through the substrate 102 from the light emission extraction unit 110 (the pores of the anode 104). And go outside. That is, the light emitted from the organic light emitting layer 108 is taken out through the substrate 102 only from the anode 104 side. As described above, in the surface-emitting light source according to the third embodiment, similarly to the first embodiment, by providing the light emission extraction unit 110, light emission can be efficiently extracted even when an opaque metal or alloy is used as the electrode material. Can do. In addition, by using a metal or alloy excellent in thermal conductivity and electrical conductivity, the organic EL element is hardly deteriorated and the light emission intensity distribution becomes uniform.

  The size of the pores is preferably in a range in which light emitted from the organic light emitting layer 108 can be taken out more efficiently and the emission intensity distribution on the light emitting surface becomes smaller, specifically, the same as a circle having a diameter of 1 to 10,000 μm. It is desirable to have an area. The width of the anode 104 partitioning between the pores may be different depending on the location, but is preferably narrow enough not to impair the conductivity of the anode 104 at any location. Desirably, it is in the range of 1-1000 μm. The thickness of the anode 104 is preferably thick enough to exhibit high light reflectivity and conductivity, specifically 0.05 to 1000 μm, more preferably 0.1 to 100 μm. .

  In the third embodiment, the shape of the pores may be any shape as long as light emitted from the organic light emitting layer 108 can be efficiently extracted and the light emission intensity distribution on the light emitting surface becomes small. Good.

  In the third embodiment, the anode 104 and the power source are connected by the connection unit 112, but the present invention is not limited to this. For example, a through hole is formed in the substrate 102 so as to correspond to at least a part of the anode 104 formed on the transparent substrate 102, and the side opposite to the surface on which the anode 104 is formed on the substrate 102. A connecting portion for connecting the anode 104 and the power source may be formed on the surface. In this case, the anode 104 is connected to the connection portion through the through hole.

<Embodiment 4>
About the surface emitting light source which concerns on Embodiment 4 of this invention, FIG. 4-1 shows a perspective view, FIG. 4-2 shows sectional drawing cut | disconnected along AB of FIG. 4-1. In the surface-emitting light source of Embodiment 4, the organic electroluminescent element has an anode 104, a cathode 106, and an organic light-emitting layer 108 sandwiched between the anode 104 and the cathode 106. Further, the anode 104 is formed in a uniform plane shape, and the cathode 106 is formed in a plurality of strips (five strips in FIGS. 4-1 and 4-2). A light emission extraction portion 110 is formed. In the fourth embodiment, the organic light emitting layer 108 is not formed in the light emission extraction unit 110. The cathode 106 and the power source are connected by the surface of the cathode 106.

In the surface-emitting light source of the fourth embodiment, the light emitted from the organic light-emitting layer 108 is repeatedly reflected by the anode 104 and the cathode 106, and then is emitted from the light emission extraction unit 110 (the gap between the anode 104 and the anode 104). Go out through. That is, the light emitted from the organic light emitting layer 108 is taken out through the substrate 102 only from the cathode 106 side. As described above, in the surface-emitting light source according to the fourth embodiment, similarly to the first embodiment, by providing the light emission extraction unit 110, light emission can be efficiently extracted even when an opaque metal or alloy is used as an electrode material. Can do. In addition, by using a metal or alloy excellent in thermal conductivity and electrical conductivity, the organic EL element is hardly deteriorated and the light emission intensity distribution becomes uniform.

  Furthermore, in the surface-emitting light source of Embodiment 4, the anode 104 also serves as a support for the organic electroluminescent element. As described above, in Embodiment 4, since light is extracted from the cathode 106 side, the opaque anode 104 can also serve as a support.

  The anode 104 is formed in a uniform plane as shown in FIGS. 4-1 and 4-2. The anode 104 is formed of an opaque metal or alloy having high light reflectivity and excellent electrical conductivity and thermal conductivity. Specific examples and preferred ranges of such an anode material are the same as those in the first embodiment.

  The thickness of the anode 104 is preferably thick enough to exhibit high light reflectance and conductivity, and thick enough to support the organic electroluminescent element, specifically 0.05 to 1000 μm, More preferably, it is in the range of 0.1 to 100 μm.

Further, for the purpose of improving hole injection into the organic light emitting layer 108, the surface of the anode 104 is made of SiO _2.
And a conductive polymer such as metal oxide such as MoO ₃ , fluorocarbon and polypyrrole, and may be coated with a layer of usually 0.1 to 30 nm, preferably 0.1 to 10 nm.

The anode 104 is obtained, for example, by polishing the surface of a substrate obtained by molding an anode material into a plate shape and flattening the surface.
The organic light emitting layer 108 is uniformly formed on the upper surface of the anode 104 as shown in FIGS. The organic light emitting layer 108 is made of a known material. Specific examples of such materials, a method of forming the organic light emitting layer 108, and preferred ranges thereof are the same as those in the first embodiment.

  The cathode 106 is formed in a strip shape on the organic light emitting layer 108 as shown in FIGS. The cathode 106 is made of an opaque metal or alloy having high light reflectivity and excellent electrical conductivity and thermal conductivity. Specific examples of such a cathode material are the same as those in the first embodiment.

  The width of the cathode 106 is preferably narrow enough not to impair the conductivity of the cathode 106. Specifically, the width is preferably in the range of 0.1 to 1000 μm. Further, when the width of the cathode 106 is within this range, the light emission of the organic EL element can be visually recognized as a surface light source. The thickness of the cathode 106 is preferably thick enough to exhibit high light reflectivity and conductivity, specifically 0.05 to 1000 μm, more preferably 0.1 to 100 μm. . The width of the light emission extraction portion 110 (the interval between the cathode 106 and the adjacent cathode 106) is preferably within a range in which light emitted from the organic light emission layer 108 can be extracted more efficiently and the light emission intensity distribution on the light emission surface becomes smaller. Specifically, it is desirable to be in the range of 1 to 10,000 μm, more preferably 1 to 5000 μm.

The method for forming the cathode 106 is the same as the method for forming the anode 104 of the first embodiment.
<Embodiment 5>
About the surface emitting light source which concerns on Embodiment 5 of this invention, sectional drawing is shown to FIGS. This sectional view is upside down from the sectional view shown in FIG. In the surface-emitting light source according to the fifth embodiment, the organic electroluminescent element includes the anode 104, the cathode 106, and the organic light-emitting layer 108 sandwiched between the anode 104 and the cathode 106, as in the fourth embodiment. The cathode 106 is formed in a plurality of strips (five strips in FIG. 5A), and a light emission extraction portion 110 is formed between the plurality of strips of cathodes 106.

In the fifth embodiment, unlike the fourth embodiment, the organic electroluminescent element further includes a transparent substrate 102, and the cathode 106 is formed on the transparent substrate 102. In the fifth embodiment, the organic light emitting layer 108 is also formed in the light emission extraction unit 110. Further, the cathode 106 and the power source are connected by the surface (connection portion) of the cathode 106 where the organic light emitting layer 108 is not formed.

  In the fifth embodiment, unlike the fourth embodiment, the anode 104 is formed in a uniform plane and is formed so as to cover the outer edge of the organic light emitting layer 108. That is, the anode 104 is formed so as to uniformly cover the upper surface and the side surface (the side surface that is parallel to the longitudinal direction of the cathode 106 and has no connection portion) of the organic light emitting layer 108. The anode 104 is formed so as to be in contact with the substrate 102 on the side surface of the organic light emitting layer 108. Furthermore, in the fifth embodiment, the organic light emitting layer 108 is also formed in the light emission extraction unit 110.

  Thus, in the surface-emitting light source of Embodiment 5, the anode 104 covers the outer edge of the organic light emitting layer 108 so that light does not leak out from the outer edge of the organic light emitting layer 108. Therefore, light emission can be taken out from the cathode 106 side more efficiently.

  In order to manufacture the anode 104 in the form as described above, first, the light emitting layer is formed so as to have an area smaller than the upper surface of the substrate, leaving the outer edge portion of the substrate on which the cathode is formed. In the same manner as described above, an anode having a larger area than the light emitting layer is formed.

  In the fifth embodiment, the cathode 106 and the power source are connected by the connecting portion, but the present invention is not limited to this. For example, a through hole 202 is formed in the substrate 102 so as to correspond to at least a part of the cathode 106 formed on the transparent substrate 102, and is opposite to the surface on which the cathode 106 is formed on the substrate 102. A connecting portion 204 that connects the cathode 106 and the power source may be formed on the side surface (see FIG. 5B). In this case, the anode 104 is connected to the connecting portion 204 through the through hole 202. In this aspect, as described above, since all the emitted light emitted from the side surface of the light emitting layer can be reflected, the emitted light can be extracted from the light emitting surface more efficiently.

<Embodiment 6>
About the surface emitting light source which concerns on Embodiment 6 of this invention, sectional drawing is shown to FIGS. 6-1. In the surface-emitting light source according to the sixth embodiment, the organic electroluminescent element includes the anode 104, the cathode 106, and the organic light-emitting layer 108 sandwiched between the anode 104 and the cathode 106, as in the fourth embodiment. The anode 104 is formed in a uniform plane. The cathode 106 and the power source are connected by the surface of the cathode 106.

In the sixth embodiment, unlike the fourth embodiment, the cathode 106 is formed in a planar shape having a plurality of pores (square holes), and the light emission extraction portion 110 is formed by a plurality of pores.
In the surface-emitting light source of Embodiment 6, the light emitted from the organic light-emitting layer 108 is repeatedly reflected by the anode 104 and the cathode 106, and then passes through the substrate 102 from the light emission extraction unit 110 (the pores of the cathode 106). And go outside. That is, the light emitted from the organic light emitting layer 108 is taken out through the substrate 102 only from the cathode 106 side. As described above, in the surface-emitting light source according to the sixth embodiment, as in the fourth embodiment, by providing the light emission extraction unit 110, light emission can be efficiently extracted even when an opaque metal or alloy is used as the electrode material. Can do. In addition, by using a metal or alloy excellent in thermal conductivity and electrical conductivity, the organic EL element is hardly deteriorated and the light emission intensity distribution becomes uniform.

The size of the pores, the width of the cathode 106 partitioning between the pores, the thickness of the cathode 106, and the shape of the pores are the same as those of the pores and the cathode 106 of the third embodiment.
<Embodiment 7>
In the surface-emitting light source according to Embodiment 7 of the present invention, an organic electroluminescent element similar to that of Embodiment 1 is used, and the organic electroluminescent element is at least a part of light emitted from the organic light-emitting layer 108. And an absorption layer made of a material that emits light having a wavelength different from that of the absorbed light (hereinafter, also referred to as “material that absorbs light”). Further, this absorption layer is formed in the light emission extraction portion 110. Specifically, an absorption layer is formed on the substrate surface 114 sandwiched between the anodes 104 shown in FIG.

The color of light observed from such a surface emitting light source is a color obtained by mixing light emitted from a material that absorbs light and light emitted from the organic light emitting layer 108.
Further, by forming an absorption layer having the same thickness as the anode 104 between the anodes 104, the dents are eliminated. Therefore, in this case, when the organic light emitting layer 108 is formed thereon, there is an advantage that the organic light emitting layer 108 having a flat surface can be easily formed.

  Examples of the material that absorbs light include known organic phosphors such as coumarin dyes and rhodamine dyes, and known inorganic phosphors such as barium-aluminum-magnesium phosphors and sulfide phosphors.

In the seventh embodiment, the same organic electroluminescent element as in the second to sixth embodiments may be used.
<Other embodiments>
In Embodiments 1 to 7 of the present invention, the surface emitting light source may be sealed with a metal oxide film, a sealing material in which a glass plate or a metal plate is attached to a substrate with an adhesive.

  Further, a hole injection layer or a hole transport layer made of an organic compound may be laminated between the anode 104 and the organic light emitting layer 108. Between the organic light emitting layer 108 and the cathode 106, a hole blocking layer, an electron transporting layer, an electron injecting layer, a dielectric layer (for example, a layer of alkali metal or alkaline earth metal halide or oxide). May be laminated.

1-1 is a perspective view of a surface-emitting light source according to Embodiment 1 of the present invention. FIG. FIG. 1-2 is a cross-sectional view taken along line AB of FIG. 1-1. 1-3 is a figure for demonstrating the surface emitting light source which concerns on Embodiment 1 of this invention. 1-4 is a figure for demonstrating the surface emitting light source which concerns on Embodiment 1 of this invention. 1-5 is a figure for demonstrating the surface emitting light source which concerns on Embodiment 1 of this invention. FIG. 2-1 is a perspective view of a surface-emitting light source according to Embodiment 2 of the present invention. FIG. 2-2 is a cross-sectional view taken along line AB of FIG. 2-1. FIGS. 2-3 is a figure for demonstrating the surface emitting light source which concerns on Embodiment 2 of this invention. FIG. 3-1 is a perspective view of a surface-emitting light source according to Embodiment 3 of the present invention. FIG. 3-2 is a cross-sectional view taken along line AB of FIG. 3-1. FIG. 3-3 is a diagram for explaining a surface-emitting light source according to Embodiment 3 of the present invention. FIG. 4-1 is a perspective view of a surface-emitting light source according to Embodiment 4 of the present invention. FIG. 4B is a cross-sectional view taken along line AB in FIG. FIG. 5-1 is a cross-sectional view of a surface-emitting light source according to Embodiment 5 of the present invention. 5-2 is a figure for demonstrating the surface emitting light source which concerns on Embodiment 5 of this invention. FIG. 6A is a cross-sectional view of a surface-emitting light source according to Embodiment 6 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 102: Transparent substrate 104: Anode 106: Cathode 108: Organic light emitting layer 110: Light emission extraction part 112: Connection part 114: Board | substrate surface pinched | interposed between anodes 202: Through-hole 204: Connection part

Claims (17)

A surface-emitting light source using an organic electroluminescent element,
The organic electroluminescent device has an anode, a cathode, and an organic light emitting layer sandwiched between the anode and the cathode,
The anode and the cathode are formed of an opaque metal or alloy having light reflectivity,
One of the anode and the cathode is formed in a uniform surface, and the other is formed in an intermittent manner so as to have a plurality of light emission extraction portions. The cathode is formed in a uniform plane, the anode is formed in a plurality of strips,
The surface emitting light source according to claim 1, wherein the light emission extraction portion is formed between a plurality of strip-shaped anodes. The cathode is formed in a uniform plane, the anode is formed in a plane having a plurality of pores,
The surface emitting light source according to claim 1, wherein the light emission extraction portion is formed by a plurality of pores. The organic electroluminescent element further has an absorption layer made of a material that absorbs at least a part of light emitted from the organic light emitting layer and emits light having a wavelength different from the absorbed light,
The surface-emitting light source according to claim 2, wherein the absorption layer is formed in the light emission extraction portion.   The surface emitting light source according to claim 2, wherein the cathode is formed to cover an outer edge of the organic light emitting layer. The organic electroluminescent device further comprises a transparent substrate;
The surface-emitting light source according to claim 5, wherein the anode is formed on the transparent substrate. Furthermore, a through hole is formed in the substrate so as to correspond to at least a part of the anode formed on the transparent substrate,
On the surface opposite to the surface on which the anode is formed on the substrate, a connection portion for connecting the anode and the power source is formed,
The surface emitting light source according to claim 6, wherein the anode is connected to the connection portion through the through hole. The anode is formed in a uniform plane, the cathode is formed in a plurality of strips,
The surface emitting light source according to claim 1, wherein the light emission extraction portion is formed between a plurality of strip-like cathodes. The anode is formed in a uniform plane, and the cathode is formed in a plane having a plurality of pores;
The surface emitting light source according to claim 1, wherein the light emission extraction portion is formed by a plurality of pores. The organic electroluminescent element further has an absorption layer made of a material that absorbs at least a part of light emitted from the organic light emitting layer and emits light having a wavelength different from the absorbed light,
The surface-emitting light source according to claim 8 or 9, wherein the absorption layer is formed in the light emission extraction portion.   The surface emitting light source according to claim 8, wherein the anode is formed so as to cover an outer edge of the organic light emitting layer. The organic electroluminescent device further comprises a transparent substrate;
The surface emitting light source according to claim 11, wherein the cathode is formed on the transparent substrate. Furthermore, a through hole is formed in the substrate so as to correspond to at least a part of the cathode formed on the transparent substrate,
On the surface opposite to the surface on which the cathode is formed on the substrate, a connection portion for connecting the cathode and the power source is formed,
The surface emitting light source according to claim 12, wherein the cathode is connected to the connecting portion through the through hole.   The surface emitting light source according to claim 8 or 9, wherein the anode also serves as a support for an organic electroluminescent element.   The surface emitting light source according to any one of claims 1 to 14, wherein the organic light emitting layer is formed from a solution containing a polymer material.   The method for producing a surface-emitting light source according to claim 15, further comprising: applying a solution containing the polymer material, and heating the glass material to a glass transition temperature or higher to form an organic light-emitting layer. .   The white illuminating device using the surface emitting light source in any one of Claims 1-15.

Images