JP2002056968A - Luminous device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminous device in which the width of spectrum of the wavelength of the emitted light is by far narrower than the conventional organic electroluminescent element and which is excellent in wavelength selection and capable of emitting light with directivity, and which is applicable not only for display but also for optical communications. SOLUTION: The top end light emitting luminous device 1000 comprises a substrate 10, a high refraction index medium layer 22, a positive electrode 12, an organic electroluminescent layer 16 that is capable of emitting light by an electroluminescence, and a negative electrode 18. A diffraction grating 14 is provided between the positive electrode 12 and the luminous layer 16. The high refractive index medium layer 22 (TiO2) has a higher index of refraction than the positive electrode (ITO) 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device using EL (electroluminescence).

[0002]

2. Description of the Related Art For example, a semiconductor laser is used as a light source used in an optical communication system. A semiconductor laser is preferable because it has excellent wavelength selectivity and can emit a single-mode light, but requires many times of crystal growth and is not easy to fabricate.
Further, the semiconductor laser has a drawback that the light emitting material is limited and light of various wavelengths cannot be emitted.

Further, the conventional EL light emitting device has a wide spectral width of an emission wavelength and is applied to some uses such as a display body, but is used for an application requiring light with a narrow spectral width such as optical communication. Was unsuitable.

It is an object of the present invention to provide a light emitting device having a spectral width of an emission wavelength which is much narrower than that of a conventional EL light emitting device, and has directivity, which can be applied not only to a display but also to optical communication.
A light emitting device is provided.

[0005]

A light-emitting device according to the present invention comprises an anode, a cathode, a light-emitting layer disposed between the anode and the cathode, and capable of emitting light by electroluminescence; A high-refractive-index medium layer disposed outside the anode and having a higher refractive index than the anode.

Further, the light emitting device according to the present invention comprises a substrate, an anode, a cathode, a light emitting layer disposed between the anode and the cathode and capable of emitting light by electroluminescence, the anode and the light emitting layer. And a diffraction grating disposed between the substrate and the anode, and
A high refractive index medium layer having a higher refractive index than the anode.

According to the light emitting device of the present invention, electrons and holes are injected into the light emitting layer from the pair of electrode layers, ie, the cathode and the anode, and the electrons and holes are recombined in the light emitting layer. Light is generated when the molecule returns from the excited state to the ground state. The light generated in the light emitting layer has wavelength selectivity and directivity due to a diffraction grating, that is, a grating in which two types of medium layers having different refractive indexes are alternately and periodically arranged.

[0008] A feature of the present invention is to reduce the light confinement coefficient at the cathode by disposing a high refractive index medium layer having a higher refractive index than the anode between the substrate and the anode. What you can do. As a result, the light emitting device of the present invention can obtain light having a small spectral width and a desired wavelength with high efficiency because light absorption at the cathode is small.

In the present invention, the thickness of the high refractive index medium layer can be set to 0.4 μm or less. According to this, the confinement coefficient of light at the cathode is set to a predetermined value or less (for example,
0.1 or less).

In the present invention, the thickness of the high refractive index medium layer can be set to 0.1 μm to 0.4 μm. According to this, the light confinement coefficient at the cathode can be set to a predetermined value or less (for example, 0.05 or less).

The high refractive index medium layer may have a higher refractive index than the anode. The material constituting the high refractive index medium layer includes TiO ₂ , Ta ₂ O ₅ , Si ₃ N ₄ , CeO ₂
And the like, and include at least one of them.

The material constituting the anode is IT
O, CuI, SnO ₂ , ZnO and the like can be exemplified, and at least one of them is included.

In the present invention, the confinement coefficient of the cathode can be set to 0.1 or less, further, 0.05 or less. According to this, the absorption at the cathode can be reduced, and the luminous efficiency can be increased.

In the present invention, of the TE wave and the TM wave,
Mainly, TE waves can be emitted. And in the present invention, the refractive index n (anode) of the anode
And the refractive index n (EL) of the light emitting layer is n (anode) <
n (EL). According to this, T
Since the difference between the confinement coefficient of the cathode in the M mode and that in the TE mode can be increased, a TE wave whose propagation mode is particularly sharp can be efficiently obtained.

The diffraction grating has a first medium layer made of a material forming an anode and a second medium layer made of a material forming a light emitting layer.
And a medium layer of the following.

It is preferable that the diffraction grating is a distributed feedback type or a distributed Bragg reflection type diffraction grating. Thus, by forming a distributed feedback type or a distributed Bragg reflection type diffraction grating, the light obtained in the light emitting layer resonates, and as a result, it has wavelength selectivity, narrow emission spectrum width, and excellent directivity. Light having a property can be obtained. In these diffraction gratings, the pitch and depth of the diffraction grating are set according to the wavelength of the emitted light.

Further, the diffraction grating of the distributed feedback type has a wavelength of λ /
By using a four-phase shift structure or a gain-coupling type structure, emitted light can be made to have a single mode. Here, λ represents the wavelength of light in the optical waveguide.

In particular, it is a desirable configuration common to the light emitting devices according to the present invention that the diffraction grating is of a distributed feedback type and further has a λ / 4 phase shift structure or a gain coupling type structure.

The present invention can include a hole transport layer disposed between the anode and the light emitting layer.

The present invention may include an electron transport layer disposed between the cathode and the light emitting layer.

The light emitting layer may include an organic light emitting material as a light emitting material. By using an organic light emitting material, a wider range of materials can be selected than in the case of using a semiconductor material or an inorganic material, and light of various wavelengths can be emitted. When the light emitting layer is an organic light emitting layer using an organic light emitting material, the light emitting layer may further include at least one of a hole transport layer and an electron transport layer. The layer functioning as the cladding layer may be a layer having a lower refractive index than the light propagation layer (core layer), and is not limited to a layer only for confining light, but may also be an electrode layer, a substrate, a hole transport layer, It can also serve as an electron transport layer and the like.

The wavelength of light emitted from the light emitting device of the present invention is 450 nm to 650 nm.

Next, some of the materials that can be used for each part of the light emitting device according to the present invention will be described. These materials are only a part of known materials, and it is a matter of course that materials other than those exemplified can be selected.

(Light Emitting Layer) The material of the light emitting layer is selected from known compounds in order to obtain light having a predetermined wavelength. The material of the light emitting layer may be either an organic compound or an inorganic compound, but is preferably an organic compound from the viewpoint of abundant types and film-forming properties.

Examples of such an organic compound include, for example,
Aromatic diamine derivatives (TPD), oxydiazole derivatives (PBD), oxydiazole dimers (OXD) disclosed in JP-A-10-153967
-8), distilylylene derivative (DSA), beryllium-benzoquinolinol complex (Bebq), triphenylamine derivative (MTDATA), rubrene, quinacridone, triazole derivative, polyphenylene, polyalkylfluorene, polyalkylthiophene, azomethine zinc complex, Porphyrin zinc complex, benzoxazole zinc complex, phenanthroline europium complex and the like can be used.

More specifically, examples of the material for the organic light emitting layer include those described in JP-A-63-70257 and JP-A-63-1758.
No. 60, JP-A-2-135361, 2-1.
JP-A-35359, JP-A-3-152184, JP-A-8-248276 and JP-A-10-1539
Known materials such as those described in JP-A-67 can be used. These compounds may be used alone or as a mixture of two or more.

As inorganic compounds, ZnS: Mn (red region), ZnS: TbOF (green region), SrS: C
u, SrS: Ag, SrS: Ce (blue region), and the like.

(Substrate) Known inorganic and organic materials can be used for the substrate or the cladding layer provided as necessary.

Representative inorganic materials include, for example,
As disclosed in JP-A-5-273427, Ti
O_Two, TiO_Two-SiO_TwoMixture, ZnO, Nb_TwoO_Five, S
i_ThreeN _Four, Ta_TwoO_Five, HfO_TwoOr ZrO_TwoFor example
Can be

As typical organic materials, known resins such as various thermoplastic resins, thermosetting resins, and photocurable resins can be used. These resins are appropriately selected in consideration of a method of forming a layer and the like. For example, by using a resin that can be cured by at least one of heat and light, a general-purpose exposure apparatus, a baking furnace, a hot plate, or the like can be used.

As such a substance, for example, there is an ultraviolet curable resin disclosed in Japanese Patent Application No. 10-279439 filed by the present applicant. Acrylic resin is suitable as the UV-curable resin. By using various commercially available resins and photosensitizers, it is possible to obtain an ultraviolet-curable acrylic resin which is excellent in transparency and can be cured by a short-term treatment.

Specific examples of the basic constitution of the ultraviolet-curable acrylic resin include a prepolymer, an oligomer and a monomer.

As the prepolymer or oligomer,
For example, acrylates such as epoxy acrylates, urethane acrylates, polyester acrylates, polyether acrylates, and spiroacetal acrylates; methacrylates such as epoxy methacrylates, urethane methacrylates, polyester methacrylates, and polyether methacrylates; Is available.

As the monomer, for example, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N-vinyl-2-pyrrolidone, carbitol acrylate, tetrahydrofurfuryl acrylate, isovol Monofunctional monomers such as nyl acrylate, dicyclopentenyl acrylate, and 1,3-butanediol acrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate,
Bifunctional monomers such as neopentyl glycol dimethacrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate,
Polyfunctional monomers such as pentaerythritol triacrylate and dipentaerythritol hexaacrylate can be used.

(Hole transporting layer) As a material of the hole transporting layer provided as needed, a material used as a hole injecting material of a known photoconductive material or a hole injecting layer of an organic light emitting device can be used. It can be used by selecting from known ones. The material of the hole transport layer has a function of injecting holes or blocking electrons, and may be an organic substance or an inorganic substance. As a specific example, see, for example,
No. 48276 can be exemplified.

(Electron transporting layer) The material of the electron transporting layer provided as necessary may have a function of transmitting electrons injected from the cathode to the organic light emitting layer, and the material may be a known substance. You can choose from. Specific examples thereof include those disclosed in JP-A-8-248276.

(Electrode Layer) As the cathode, an electron-injecting metal, alloy conductive compound, or a mixture thereof having a small work function (for example, 4 eV or less) can be used.
Examples of such an electrode material include, for example, JP-A-8-248.
No. 276 can be used.

As the anode, a metal, an alloy, an electrically conductive compound or a mixture thereof having a large work function (for example, 4 eV or more) can be used. When an optically transparent material is used for the anode, CuI, ITO, SnO
₂ , conductive transparent materials such as ZnO can be used,
When transparency is not required, a metal such as gold can be used.

In the present invention, the method of forming the diffraction grating is not particularly limited, and a known method can be used. Representative examples are shown below.

Lithography Method A positive or negative resist is exposed and developed with ultraviolet rays or X-rays to pattern the resist layer.
Create a diffraction grating. As a patterning technique using a resist such as polymethyl methacrylate or a novolak resin, there are, for example, JP-A-6-224115 and JP-A-7-20637.

A technique for patterning polyimide by photolithography is disclosed in, for example,
181689 and 1-222141. Furthermore, as a technique for forming a diffraction grating of polymethyl methacrylate or titanium oxide on a glass substrate by using laser ablation, there is, for example, Japanese Patent Application Laid-Open No. 10-59743.

Method of Forming Refractive Index Distribution by Light Irradiation A light diffraction portion is irradiated with light having a wavelength that causes a change in the refractive index to a light propagation portion, and a portion having a different refractive index is periodically formed in the light propagation portion to thereby form a diffraction grating. To form As such a method, it is particularly preferable to form a layer of a polymer or a polymer precursor, partially polymerize the layer by light irradiation or the like, and periodically form regions having different refractive indexes to form a diffraction grating. . As this kind of technology, for example, Japanese Patent Laid-Open No. 9-31
1238, 9-178901, 8-1
Nos. 5506, 5-297202, 5-3
No. 2523, No. 5-39480, No. 9-21
Nos. 1728, 10-26702, 10-
Nos. 8300 and 2-51101.

Method by stamping Hot stamping using a thermoplastic resin (Japanese Unexamined Patent Publication No.
No. 201907), stamping using an ultraviolet curable resin (Japanese Patent Application No. 10-279439), stamping using an electron beam curable resin (Japanese Unexamined Patent Publication No. 7-235075).
A diffraction grating is formed by stamping as described in Japanese Unexamined Patent Publication (Kokai) No. H11-209686.

Etching Method A thin film is selectively removed and patterned by lithography and etching to form a diffraction grating.

The method of forming the diffraction grating has been described above. In short, the diffraction grating only needs to be composed of two regions having different refractive indices, and two regions having different refractive indices are formed. It can be formed by a method, a method of forming two regions having different refractive indexes by partially modifying a kind of material, or the like.

Each layer of the light emitting device can be formed by a known method. For example, a suitable film forming method is selected for the light emitting layer depending on its material, and specific examples include a vapor deposition method, a spin coating method, an LB method, and an ink jet method.

[0047]

FIG. 1 shows an edge-emitting type light emitting device (hereinafter referred to as "organic light emitting device") 10 according to the present embodiment.
FIG. 2 is a perspective view schematically showing 00, and FIG.
It is sectional drawing of the principal part along the A line.

(Structure) The organic light emitting device 1000 is
0, the high refractive index medium layer 22, the anode 12, the organic light emitting layer 1
6 and the cathode 18 are stacked in this order.

In the organic light emitting device 1000, the refractive index of the substrate 10 is set smaller than the refractive index of the high refractive index medium layer 22.

The high-refractive-index medium layer 22 has a higher refractive index than the anode 12.
In the case of TO, TiO ₂ and Ta ₂ O ₅ can be exemplified. By arranging such a high refractive index medium layer 22 between the substrate 10 and the anode 12, it is possible to reduce the light confinement coefficient at the cathode. The details will be described later.

The diffraction grating 14 is arranged between the anode 12 and the organic light emitting layer 16. The diffraction grating 14 has a first medium layer 14 a and a second medium layer 14 having different refractive indexes.
b. The first medium layer 14a is made of a material constituting the anode 12, and the second medium layer 14b is made of the organic light emitting layer 1
6 is composed of the substance.

Since the anode 12 constitutes the first medium layer 14a of the diffraction grating 14, it is made of a conductive material transparent to emitted light. As the material of such a transparent electrode, the above-mentioned materials can be used.

The diffraction grating 14 is preferably a distributed feedback type diffraction grating. By forming a distributed feedback type diffraction grating in this manner, light can resonate in the optical waveguide, and light with excellent wavelength selectivity and directivity and a narrow emission spectrum width can be obtained. Further, although not shown, the diffraction grating 14 preferably has a λ / 4 phase shift structure or a gain coupling type structure. By having the λ / 4 phase shift structure or the gain-coupling type structure as described above, the emitted light can be made into a single mode.

The organic light emitting layer 16 and the cathode 18 are composed of the above-mentioned materials. Further, the thicknesses of the organic light emitting layer 16 and the cathode 18 are not particularly limited. The organic light emitting layer 16
For example, considering the light emitting function, conductivity, etc., 0.1 to 1
It can have a thickness of μm. The cathode 18 is
For example, in consideration of conductivity, 0.05 to 0.1 μm
Thickness.

In the organic light emitting device 1000, the core layer 100 is mainly constituted by the high refractive index medium layer 22, the anode 12, the diffraction grating 14, and the organic light emitting layer 16, and the cladding layer is constituted by the substrate 10 and the cathode 18.

Another structure: In the organic light emitting device 1000, as shown in FIG.
Is formed, and a second coating layer 20b having high reflectivity is formed on the other end face. For these coating layers, for example, a dielectric multilayer mirror generally used in a semiconductor DFB laser can be used.

As the method of manufacturing the diffraction grating and the organic light emitting layer of the organic light emitting device 1000 and the materials constituting each layer, the above-described methods and materials can be appropriately used. For example, in forming the diffraction grating 14, a method using stamping, which has a relatively simple process, can be preferably used.

(Analysis of Propagation Mode) Next, the propagation mode of the light emitting device having the basic configuration of the organic light emitting device 1000 of the present embodiment will be described with reference to FIG. FIG.
3 shows a basic configuration of the light emitting device and propagation modes corresponding to each component thereof. The configuration of the light emitting device is
1 and 2 are designated by the same reference numerals. The structure shown in FIG. 3 differs from the present invention in that the high refractive index medium layer 22 is not provided. In FIG. 3, a region indicated by reference numeral “a” corresponds to the cathode 18.

From the propagation mode, the light confinement coefficient at the cathode 18 can be analyzed. The propagation mode is, for example,
Document `` International Journal of Optoelectronic
s, 1995, vol. 10, No. 5, pages 331-
335 "can be obtained by a general mode calculation. Hereinafter, the light confinement coefficient and the like will be described in detail.

In the light emitting device 1000, usually, the cathode 1
8 is made of metal, so that light absorption becomes very large. When light emission is observed from the anode side as in a display, light absorption at the cathode 18 is not so problematic. However, in the light emitting device of the edge emission type as in the present invention, it is presumed that the absorption of light at the cathode 18 becomes a serious problem in terms of luminous efficiency. Therefore, in order to increase the luminous efficiency of the light emitting device, it is necessary that the propagation mode does not overlap with the cathode 18 as much as possible.

As an index indicating the overlap between the cathode and the propagation mode, usually, the confinement coefficient at the cathode is used. Here, the confinement coefficient is an integral value of the propagation mode of the region indicated by the symbol “a” in FIG. 3 and reflects the area S100 of this region. That is, the confinement coefficient is determined by the area S
It increases in proportion to 100. Then, in order to reduce light absorption at the cathode, it is necessary to make the confinement coefficient at the cathode as close to zero as possible. In this embodiment, since the high refractive index medium layer 22 having a higher refractive index than the anode 12 is disposed between the substrate 10 and the anode 12, the area S100 can be reduced.

The propagation mode changes depending on the number of layers constituting the light emitting device, the material and thickness of the layers, and the confinement coefficient changes accordingly. In the light emitting device, in order to achieve higher luminous efficiency, it is important to reduce the light confinement coefficient at the cathode 16. For that purpose, the confinement coefficient is preferably 0.1 or less, more preferably 0.
05 or less.

(Operation and Function) Next, the operation and function of the organic light emitting device 1000 will be described.

When a predetermined voltage is applied to the anode 12 and the cathode 18, electrons are injected from the cathode 18 and holes are injected from the anode 12 into the organic light emitting layer 16. In the organic light emitting layer 16, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. The wavelength λ of light is desirably in the range of the wavelength of visible light (450 to 650 nm).

The light generated in the organic light emitting layer 16 is partially reflected by the substrate 10 and the cathode 18, and partially propagates through the anode 12 and the organic light emitting layer 16 as it is. In the core layer 100, the light is distributed-propagation-type propagated by the diffraction grating 14, propagates in the core layer 100 toward the end face, and forms the first coating layer 20 having a low reflectance.
a. Since the emitted light is distributed and fed back by the core layer 100 by the diffraction grating 14, the emitted light has wavelength selectivity, a narrow emission spectrum width, and excellent directivity. Furthermore, by making the diffraction grating 14 a λ / 4 phase shift structure or a gain-coupling structure, the outgoing light can be made into a single mode. Where λ is
Represents the wavelength of light in the optical waveguide.

The characteristic features of this embodiment are as follows.
By arranging the high refractive index medium layer 22 having a higher refractive index than the anode 12 between the substrate 10 and the anode 12, the confinement coefficient at the cathode can be reduced. As a result, the light emitting device 10
Since 00 has little absorption of light at the cathode, light of a desired wavelength can be obtained with high efficiency.

(Simulation Example) With respect to the light emitting device of the present invention, the relationship between the light confinement coefficient at the cathode and the thickness of the high refractive index medium layer 22 was examined by simulation. The light-emitting device used in the simulation has the basic structure of the light-emitting device 1000 shown in FIGS. 1 and 2, that is, the light-emitting device 1000 includes a substrate 10, a high-refractive-index medium layer 22, an anode 12, and a diffraction grating (an anode and an organic light-emitting layer). 14, an organic light emitting layer 16 and a cathode 18.

(1) Sample of Light Emitting Device ITO was used as the anode, and its thickness T1 was 0.15 μm.
m (including the portion of the diffraction grating), the thickness T2 of the diffraction grating is 0.05 μm, the thickness T3 of the organic light emitting layer is 0.1 μm (including the portion of the diffraction grating), and the thickness T4 of the cathode is 5 μm.
Set to. The substrate was sufficiently thicker than other layers, for example, set to 5 μm. TiO ₂ was used as the high refractive index medium layer 22, and its thickness T5 was set to 0.1 μm.

As a sample, (A) a sample in which the refractive index n (anode) of the anode (hereinafter referred to as the refractive index n (ITO)) is larger than the refractive index n (EL) of the organic light emitting layer, ie, n
(ITO)> n (EL) sample (hereinafter referred to as “sample A”), and (B) anode refractive index n (ITO)
Is smaller than the refractive index n (EL) of the organic light emitting layer, that is, a sample of n (ITO) <n (EL) (hereinafter, this is referred to as “sample B”).

(2) Method of Simulation Regarding the characteristics described below, only the 0th-order propagation mode was evaluated, and both the TE wave and the TM wave were obtained. The propagation mode is described in the document "InternationalJournal
of Opto electronics, 1995, vol. 10, N
o. 5, pages 331-335 ".

(3) Results of Simulation FIG. 4 shows the confinement coefficient of the cathode and the thickness of the high refractive index medium layer 22 (TiO ₂ layer) in the TE mode and the TM mode obtained for the samples A and B, respectively. Shows the relationship with In FIG. 4, the horizontal axis represents the high refractive index medium layer 22 (T
The thickness of the iO ₂ layers), the vertical axis represents the confinement factor of the cathode.

The confinement coefficient of the cathode in the light emitting device is preferably 0.1 or less, more preferably 0.05 or less for the above-mentioned reason. TE with a sharp propagation mode
The wave can have a confinement coefficient of 0.1 or less if the thickness of the high refractive index medium layer 22 is 0.4 μm or less. The TE wave has a confinement coefficient of 0.05 or less when the thickness of the high refractive index medium layer 22 is 0.1 μm to 0.4 μm under the condition of n (ITO) <n (EL). be able to. The TE wave can have a confinement coefficient of 0.05 or less if the thickness of the high refractive index medium layer 22 is 0.5 μm or less under the condition of n (ITO)> n (EL). .

The high refractive index medium layer 22 has a thickness of 0.1
In the case of ０．４0.4 μm, the larger the difference between the confinement coefficient in the TM mode and the TE mode (the value of the TM wave−the value of the TE wave: Δc.f.), the more efficiently the polarization control is performed, and the more the propagation mode becomes. Only sharp TE waves can be efficiently extracted. Sample B has a large confinement coefficient difference Δc.f., indicating that TE waves can be selectively extracted.

In the embodiments described above, the case where the organic light emitting layer is used as the light emitting layer has been described, but a light emitting layer made of an inorganic material may be used instead of the organic light emitting layer.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an organic light emitting device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing a main part of the organic light emitting device shown in FIG. 1 along line AA.

FIG. 3 is a diagram illustrating a propagation mode of the light emitting device.

FIG. 4 is a diagram showing the relationship between the thickness of a high-refractive-index medium layer and the light confinement coefficient at the cathode, obtained for the light-emitting device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 12 Anode 14 Diffraction grating 14a, 14b Medium layer 16 Organic light emitting layer 18 Cathode 22 High refractive index medium layer 100 Core layer

Claims (19)

[Claims] An anode, a cathode, a light emitting layer disposed between the anode and the cathode, and capable of emitting light by electroluminescence, a diffraction grating disposed between the anode and the light emitting layer, A light-emitting device comprising: a high-refractive-index medium layer disposed outside the anode and having a higher refractive index than the anode. 2. A substrate, an anode, a cathode, a light emitting layer arranged between the anode and the cathode, and capable of emitting light by electroluminescence, and a diffraction arranged between the anode and the light emitting layer. A light emitting device comprising: a lattice; a high refractive index medium layer disposed between the substrate and the anode and having a higher refractive index than the anode. 3. The light emitting device according to claim 1, wherein the high refractive index medium layer has a thickness of 0.4 μm or less. 4. The high refractive index medium layer according to claim 1, wherein the thickness of the high refractive index medium layer is 0.1 μm to 0.4 μm.
A light emitting device. 5. The high refractive index medium layer according to claim 1, wherein the high refractive index medium layer is made of TiO ₂ , Ta ₂ O ₅ , Si.
₃ N _4, CeO ₂ among light-emitting device comprising at least any one. 6. The light emitting device according to claim 1, wherein the anode includes at least one of ITO, CuI, SnO ₂ , and ZnO. 7. The light emitting device according to claim 1, wherein a confinement coefficient of the cathode is 0.1 or less. 8. The light emitting device according to claim 1, wherein a confinement coefficient of the cathode is 0.05 or less. 9. The light emitting device according to claim 1, wherein a TE wave is mainly emitted out of the TE wave and the TM wave. 10. The relation according to claim 1, wherein a refractive index n (anode) of the anode and a refractive index n (EL) of the light emitting layer are n (anode) <n (EL). A light emitting device. 11. The first diffraction grating according to claim 1, wherein the diffraction grating is made of a material constituting the anode.
And a second medium layer made of a material constituting the light emitting layer. 12. The light emitting device according to claim 1, wherein the diffraction grating is a distributed feedback diffraction grating. 13. The light emitting device according to claim 12, wherein the diffraction grating has a λ / 4 phase shift structure. 14. The light emitting device according to claim 12, wherein the diffraction grating has a gain coupling type structure. 15. The light emitting device according to claim 1, wherein the diffraction grating is a distributed Bragg reflection type diffraction grating. 16. The light emitting device according to claim 1, further comprising a hole transport layer disposed between the anode and the light emitting layer. 17. The light emitting device according to claim 1, further comprising an electron transport layer disposed between the cathode and the light emitting layer. 18. The light emitting device according to claim 1, wherein the light emitting layer contains an organic light emitting material as a light emitting material. 19. The light emitting device according to claim 1, wherein a wavelength of the light emitted from the light emitting device is 450 nm or more.
A light emitting device having a wavelength of 650 nm.