JP2002110361A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminous device in which the intensity of light in a specified direction is made large and the light can be utilized efficiently. SOLUTION: The luminous device 1,000 comprises a substrate 10 and a luminous element part 100 formed on the substrate 10. The luminous element part 100 comprises a luminous layer 40, a positive electrode 30 and a negative electrode 50 for applying an electric field to the luminous layer 40, diffraction gratings 12 and prisms 11.

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]

[Background Art and Problems to be Solved by the Invention] EL
In an EL device using (electroluminescence), light is emitted isotropically and the directivity is poor.
When viewed in a specific direction, there is a disadvantage that the light intensity is low and the emitted light cannot be used with high efficiency.

[0003] An object of the present invention is to provide a light emitting device capable of increasing the light intensity in a specific direction and using light efficiently.

[0004]

A light-emitting device according to the present invention includes a substrate and a light-emitting element formed on the substrate, wherein the light-emitting element includes a light-emitting layer capable of emitting light by electroluminescence, The light emitting device includes a pair of electrode layers for applying an electric field to the light emitting layer, a diffraction grating, and a member for changing a direction in which light propagates.

According to the light emitting device of the present invention, light is emitted in a predetermined direction by providing the light emitting element with a member for changing the direction in which light propagates. That is, when electrons and holes are injected into the light emitting layer from the pair of electrode layers, that is, the cathode and the anode, and the electrons and holes are recombined in the light emitting layer, and the molecules return from the excited state to the ground state. Light is generated. By changing the direction in which the light propagates by the member, the light can be emitted in a predetermined direction. Further, by changing the direction in which at least part of the emitted light propagates, light can be emitted in two or more directions.

In this case, light is propagated in the plane direction of the substrate by the diffraction grating, and the direction of propagation of at least a part of the light propagated in the plane direction of the substrate is changed by the member. The light can be emitted in a direction crossing the substrate.

Here, the surface direction of the substrate refers to a direction perpendicular to the thickness direction of the substrate in the substrate, and in other words, refers to a direction in which the substrate extends.

As the member, for example, a prism or a diffraction grating of the second order or higher can be used. Further, the member can be formed on at least one of the light emitting layer and the electrode layer.

When the member is a diffraction grating of the second order or higher, the light generated in the light emitting layer is controlled by the diffraction grating so as to be emitted also in a direction crossing the substrate. Here, a diffraction grating of the second order or higher refers to a diffraction grating having a pitch in the periodic direction of (a + 1) λ / 2n, for example.
(A is an integer of 1 or more, n is an average refractive index). In particular, when the member is a diffraction grating of the second order (a = 1), it is possible to obtain a light emitting device that emits light not only in the surface direction of the substrate but also in a direction perpendicular to the lamination surface of the substrate.

[0010] The diffraction grating is an optical element generally used to obtain a predetermined spectrum by utilizing light diffraction.

In this case, in the light emitting device of the present invention described above, the diffraction grating can form a photonic band gap or an incomplete photonic band. Here, an incomplete photonic band refers to a band formed when a complete photonic band gap is not formed. For example, when the diffraction grating is formed by alternately arranging the first medium layer and the second medium layer, and the difference in the refractive index between the first medium layer and the second medium layer is small. In some cases, the photonic band gap is not completely formed.

According to this structure, electrons and holes are respectively 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 to excite molecules. Light is generated when returning from the state to the ground state. That is, in the light emitting layer, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. Thus, light with a very narrow emission spectrum width can be obtained with high efficiency.

Further, as the light emitting device including the above-mentioned diffraction grating, the following first and second light emitting devices can be exemplified.

(First Light-Emitting Device) The first light-emitting device is a light-emitting device according to the above-described present invention, wherein the energy level of the light-emitting spectrum of the light-emitting layer is included in the band formed by the diffraction grating. The diffraction grating is configured to include an edge energy level.

According to the first light emitting device, a band for light is formed by the diffraction grating. In this band, a state with a high state density is obtained at a certain band edge energy. Here, the diffraction grating is configured so that the energy level of the spectrum of light emitted in the light-emitting layer includes the energy level of the band edge, so that the light emission in the light-emitting layer increases the energy of the band edge. It tends to occur at the level. For this reason, it is possible to emit light having a wavelength corresponding to the energy level of the band edge and having a narrow spectrum width,
A high-yield device can be obtained.

(Second Light Emitting Device) In the second light emitting device, a defect formed in a part of the diffraction grating and set so that an energy level caused by the defect exists in a predetermined emission spectrum. Including parts. According to this configuration, of the light generated in the light emitting layer, only light in a wavelength band corresponding to the energy level caused by the defect can propagate in the diffraction grating. Therefore, by defining the width of the energy level caused by the defect, it is possible to obtain light with a very narrow emission spectrum width and directivity, in which spontaneous emission is restricted in a predetermined direction, with high yield. .

In this case, the light emitting layer can function as at least a part of the diffraction grating. In this case, the light emitting layer can function as at least a part of the defect.

In the first and second light emitting devices described above, for example, the following modes can be adopted.

(1) It is desirable that the diffraction grating is a distributed feedback type diffraction grating or a distributed Bragg reflection type, and it is desirable that the diffraction grating has a gain coupling type structure or a refractive index coupling type structure.

(2) In the diffraction grating, it is preferable that an insulating first medium layer and a second medium layer are periodically arranged, and the diffraction grating has a periodic refractive index distribution in at least one direction. Is desirable. For example, one direction, two predetermined directions (first and second directions), or three predetermined directions (first and second directions).
(Second and third directions).

In this case, the first medium layer may be columnar and arranged in a lattice, and the second medium layer may be disposed between the first medium layers. desirable.

(3) Preferably, at least one of a hole transport layer and an electron transport layer is provided.

In this case, in the diffraction grating, a hole transport layer or an electron transport layer can constitute one medium.

In this case, the member can be formed on at least one of the hole transport layer and the electron transport layer.

(4) The light emitting layer can function as at least a part of the diffraction grating.

(5) On at least one of the electrode layers, a layer for regulating the propagation of the light may be provided.

In this case, the layer that regulates the propagation of light is
It is desirable to be a clad layer or a dielectric multilayer film.

(6) The light emitting layer can be formed in a region different from the diffraction grating.

(7) The light emitting layer preferably contains 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.

The light emitting device of the present invention described above can be used for a display.

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 of 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 light emitting material from the viewpoint of abundant types and film forming properties.

Examples of such organic light-emitting materials include, for example, aromatic diamine derivatives (TPD), oxydiazole derivatives (PBD), and oxydiazole dimers (OPD) disclosed in JP-A-10-153967.
XD-8), distilarylene 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.

As a material for the light emitting layer, Japanese Patent Application Laid-Open
JP-A-70257, JP-A-63-175860, JP-A-2-135361, JP-A-2-135359, JP-A-3-152184, and JP-A-8-248
Known ones such as those described in JP-A-276-276 and JP-A-10-153967 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.

(Hole Transport Layer) When a light emitting layer made of an organic compound is used in the light emitting element portion, a hole transport layer can be provided between the electrode layer (anode) and the light emitting layer as needed. As the material of the hole transport layer, a material used as a hole injection material of a known photoconductive material or a known material used for a hole injection layer of an organic light emitting device can be selected and used. 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. Specific examples thereof include those disclosed in Japanese Patent Application Laid-Open No. 8-248276.

(Electron Transport Layer) When a light emitting layer made of an organic compound is used in the light emitting element portion, an electron transport layer can be provided between the electrode layer (cathode) and the light emitting layer as needed. The material of the electron transporting layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and the material can be selected from known substances. Specific examples thereof include those disclosed in JP-A-8-248276.

(Electrode Layer) As the cathode, an electron injecting metal, an alloy electrically 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.

(Diffraction Grating) 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.

(1) Lithography Method A positive or negative resist is exposed and developed with ultraviolet rays, X-rays, or the like, and the resist layer is patterned to form a diffraction grating. As a patterning technique using a resist such as polymethyl methacrylate or a novolak resin, 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.

(2) Method of Forming Refractive Index Distribution by Light Irradiation Light of a wavelength that causes a change in the refractive index is applied to the optical waveguide portion of the optical waveguide, and a portion having a different refractive index is periodically applied to the optical waveguide portion. This forms a diffraction grating. 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, JP-A-9-31238 and JP-A-9-178901,
JP-A-8-15506, JP-A-5-297202,
JP-A-5-32523, JP-A-5-39480, JP-A-9-211728, JP-A-10-26702,
Nos. 10-8300 and 2-51101.

(3) 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.

(4) Etching Method A thin film is selectively removed and patterned by lithography and etching techniques 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 at least two regions having mutually different refractive indices.
It can be formed by a method of forming two regions with two kinds of materials having different refractive indexes, a method of forming two regions with different refractive indexes by partially modifying one kind of material, or the like.

(Prism) The prism can be formed by polishing, for example, an optical glass mainly composed of SiO ₂ . Also, for example, by casting, injection molding, compression molding of methyl methacrylate,
Alternatively, a prism can be obtained by molding the same material as that forming the diffraction grating, for example, optically transparent SiO ₂ , TiO ₂ , Ta ₂ O _5, or the like by etching.

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

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] (Structure of Device) FIG. 1 is a sectional view schematically showing a light emitting device 1000 according to the present embodiment, and FIG. It is sectional drawing along the AA line. 3 to 7
3 is a cross-sectional view showing a modification of the light emitting device shown in FIG.

The light emitting device 1000 comprises a substrate 10 and a substrate 1
0 on the light-emitting element portion 100. The light emitting element section 100 includes an anode 30, a light emitting layer 40, a cathode 50, a diffraction grating 12, and a prism 11. The light emitting layer 40 is formed from a material that can emit light by electroluminescence. The anode 30 and the cathode 50 are provided for applying an electric field to the light emitting layer 40.

The anode 30 is made of a transparent conductive material.
As a material for such a transparent electrode, the above-described materials such as ITO can be used.

The diffraction grating 12 has a refractive index distribution that is periodic in one direction. Here, the diffraction grating refers to an optical element generally used to obtain a predetermined spectrum using light diffraction, and refers to a structure in which two medium layers are alternately arranged. In the diffraction grating 12, as shown in FIG. 2, first medium layers 12a and second medium layers 12b having different refractive indexes are alternately arranged in the X direction. The second medium layer 12b is continuous with the light emitting layer 40. That is, the light emitting layer 40 is a part of the diffraction grating 12 (the second medium layer 12b).
Function as

The pitch in the periodic direction of the diffraction grating 12 is aλ / 2n (a is an integer of 1 or more, and n is the average refractive index).
It is formed so that it becomes. In this case, the diffraction grating 12
Becomes the a-order. Therefore, the order of the diffraction grating 12 can be set by setting the pitch of the diffraction grating 12 in the periodic direction to a predetermined value based on the above-described formula. FIGS. 1 and 2 show a case where the pitch of the diffraction grating 12 in the periodic direction is λ / 2n (a = 1 in the above equation), and the diffraction grating 12 is a first-order diffraction grating. In addition,
In FIG. 2, the pitch in the periodic direction of the diffraction grating 12 is
It refers to the sum of the widths of a pair of adjacent first medium layers 12a and second medium layers 12b.

First medium layer 12 constituting diffraction grating 12
The material of “a” is not particularly limited, and the first medium layer 12a is formed from a material in a selection range of a general material used for the light emitting device. For example, the first medium layer 12a may be a layer of a gas such as air. As described above, when the optical member is formed of a gas layer, the refractive index difference between the two media constituting the optical member can be increased within a range of selection of a general material used for the light emitting device. An efficient diffraction grating can be obtained for the wavelength of light. This modified example can be similarly applied to other embodiments.

The diffraction grating 12 used in the light emitting device 1000 according to the present embodiment forms an incomplete photonic band. Further, the diffraction grating 12 is configured so that the energy level of the emission spectrum of the light emitting layer 40 includes the energy level of the band edge included in the band formed by the diffraction grating 12. The band for light is
It is formed by the diffraction grating 12. This band is obtained with a high state density at a certain band edge energy. Further, in the light emitting layer 40, the diffraction grating 12 is configured such that the spectrum of the emitted light includes the energy level of this band edge. Therefore, light emission in the light emitting layer 40 easily occurs at the energy level of the band edge. Accordingly, a device having a wavelength corresponding to the energy level of the band edge, emitting light with a narrow spectrum width, and having a high yield can be obtained.

As the diffraction grating 12, a distributed feedback type diffraction grating is used. It has excellent wavelength selectivity and directivity, and can obtain light with a narrow emission spectrum width. further,
The diffraction grating 12 preferably has a refractive index coupling type structure or a gain coupling type structure. FIG. 1 shows a case where the diffraction grating 12 has a gain coupling type structure.

In the light emitting device 1000 of this embodiment, a prism is used as a member for changing the direction in which light propagates. As shown in FIG. 1, the prism 11 is formed on the substrate 10, penetrates the light emitting layer 40, and has a tip located at the cathode 50. In the light emitting device 1000 shown in FIG. 1, light propagates in the plane direction of the substrate 10 (X direction). In this case, light propagating in the surface direction of the substrate 10 can be propagated by the prism 11 in a direction crossing the substrate 10. FIG. 1 shows a case where the prism 11 emits light in the surface direction (X direction) of the substrate 10 and in the film thickness direction (Y direction) of the substrate, but the shape and material of the prism 11 are appropriately selected. Thereby, light can be propagated in an arbitrary direction. The location and size of the prism 11 can be appropriately set according to the amount of emitted light and the amount of light that changes the direction.

In the light emitting device 1000, the prism 11 is formed on the substrate 10. Prism 11
Is not limited to this, but is desirably a position closer to the diffraction grating 12.

The cathode 50 is formed so as to cover the surface of the light emitting layer 40. As described above, by forming the cathode 50 on the light emitting layer 40, the current can be concentratedly supplied to the light emitting layer 40, and the loss of the current can be reduced.

The propagation of light in the leak mode is allowed in directions other than the plane direction of the diffraction grating 12 (X direction in FIG. 1) and the direction crossing the diffraction grating 12 (Y direction in FIG. 1). For example, in order to suppress the propagation of light in the plane direction of the diffraction grating 12 (X direction in FIG. 1), for example, a reflection layer (not shown) can be provided as necessary. This is the same in the modified examples and other embodiments described below.

As for the method of manufacturing the diffraction grating 12 of the light emitting device 1000 and the materials constituting each layer, the above-described methods and materials can be appropriately used. These manufacturing methods and materials are the same in the following modified examples and other embodiments.

(Operation of Device) Next, the light emitting device 1
000 will be described.

By applying a predetermined voltage to the anode 30 and the cathode 50, electrons are injected from the cathode 50 and holes are injected from the anode 30 into the light emitting layer 40, respectively. In the light emitting layer 40, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. The light generated in the light emitting layer 40 is distributed-propagation-type propagated by the diffraction grating 12, propagates in the plane direction (X direction) of the substrate 10, and enters the prism 11, so that the light is substantially perpendicular to the surface of the substrate 10. The direction of propagation in the direction (Y direction) is changed and the light is emitted.

(Operation and Effect) According to the present invention, since the light emitting element section 100 includes the prism 11, the direction in which a part of the light generated in the light emitting layer 40 propagates by the prism 11 is changed. Is controlled so that light is emitted not only in the plane direction but also in a direction crossing the substrate 10.

In particular, the light emitting device 10 according to the present embodiment
In the case where the diffraction grating 12 is a first-order diffraction grating as in 00, unless a member such as the prism 11 for changing the direction in which light propagates is provided, the plane direction of the diffraction grating 12 (in FIG. Light propagates only in the X direction). On the other hand, according to the light emitting device 1000 according to the present embodiment,
By providing the prism 11, the direction in which light propagates can be changed, and light also propagates in a direction intersecting with the substrate 10 (Y direction in FIG. 1). Thereby, so-called surface light emission can be achieved.

(Modification) In the light emitting device 1000 shown in FIGS. 1 and 2, the positions where the diffraction grating 12, the prism 11 and the light emitting layer 40 are formed are changed, or other layers are provided, so that FIGS. A light emitting device including the structure exemplified in FIG. 7 can also be adopted. In these figures,
The same members as the components of the light emitting device 1000 are denoted by the same reference numerals, and the detailed description is omitted. Note that these modified examples can be similarly applied to other embodiments.

FIGS. 3 to 7 show modifications of the light emitting device according to the present embodiment (light emitting devices 1001 to 100).
It is sectional drawing which shows 5) typically.

(A) The light emitting device 1001 shown in FIG. 3 is different from the light emitting device 1000 in that the light emitting element portion 101 includes the hole transport layer 70 in that the hole transport layer is not provided.
And different. The light emitting device 1001 differs from the light emitting device 1001 in that the prism 21 is formed on the
The light emitting device 1000 is different from the light emitting device 1000 formed on the light emitting device 0.

The light emitting device 1001 comprises a substrate 10 and a substrate 1
0 on the light emitting element portion 101. The light emitting element unit 101 includes the anode 30, the hole transport layer 70, and the light emitting layer 4
0 and the cathode 50 are laminated on the substrate 10 in this order. The diffraction grating 12 is formed on the hole transport layer 70, and the prism 21 is formed on the anode 30.

Next, the operation of the light emitting device 1001 will be described.

When a predetermined voltage is applied between the anode 30 and the cathode 50, electrons are injected from the cathode 50 into the light emitting layer 40, and further, from the anode 30 into the light emitting layer 40 via the hole transport layer 70. Holes are injected. In the light emitting layer 40, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. Subsequent operations are substantially the same as those of the light emitting device 1000 according to the first embodiment.
Description is omitted.

The light emitting device 1001 has the same functions and effects as those of the light emitting device 1000 shown in FIG. 1, and also has the hole transporting layer 70, so that the hole transporting ability can be improved.

(B) In the light emitting device 1002 shown in FIG. 4, the point that the light emitting element portion 102 includes the hole transport layer 70 and the second medium layer 112b constituting the diffraction grating 112 is continuous with the hole transport layer 70 The light emitting device 1 shown in FIG.
000.

The light emitting device 1002 comprises a substrate 10 and a substrate 1
0 on the light emitting element portion 102. The light emitting element section 102 is formed by stacking the anode 30 and the prism 11, the hole transport layer 70, the light emitting layer 40, and the cathode 50 on the substrate 10 in this order.

The diffraction grating 112b is formed on the anode 30. The second medium layer 112b constituting the diffraction grating 112 is formed continuously with the hole transport layer 70. That is, the hole transport layer 70 functions as a part of the diffraction grating 112 (the second medium layer 112b).

Next, the operation of the light emitting device 1002 will be described.

When a predetermined voltage is applied to the anode 30 and the cathode 50, electrons are injected from the cathode 50 into the light emitting layer 40, and further, from the anode 30 into the light emitting layer 40 via the hole transport layer 70. Holes are injected. In the light emitting layer 40, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. Subsequent operations are substantially the same as those of the light emitting device 1000 according to the first embodiment.
Description is omitted.

Light emitting device 1002 has substantially the same operation and effect as light emitting device 1001 shown in FIG.

In FIG. 4, the hole transport layer 70
Although the example in which the diffraction grating 112 is provided inside is shown, when the anode 30 is formed of a material other than metal, for example, when formed of ITO, the diffraction grating is formed from the hole transport layer 70 and the anode 30. Is also good.

(C) In the light emitting device 1003 shown in FIG. 5, the hole transport layer 70 and the electron transport layer 80 are
3, the second medium layer 2 constituting the diffraction grating 212
The light emitting device 1000 differs from the light emitting device 1000 shown in FIG. 1 in that 12b is continuous with the electron transport layer 80 and that the prism 21 is formed on the anode 30.

The light emitting device 1003 comprises a substrate 10 and a substrate 1
And a light emitting element portion 103 formed on the light emitting element portion 0. The light emitting element section 103 includes an anode 30, a hole transport layer 70 and a prism 21, a light emitting layer 40, an electron transport layer 80, and a cathode 50.
Are formed by laminating in this order. Also,
The diffraction grating 212 is formed on the light emitting layer 40, and the second medium layer 212 b constituting the diffraction grating 212 is formed continuously from the electron transport layer 80. That is, the electron transport layer 80 is formed as a part of the diffraction grating 212 (the second medium layer 212).
Functions as b).

Next, the operation of the light emitting device 1003 will be described.

When a predetermined voltage is applied to the anode 30 and the cathode 50, electrons are injected from the cathode 50 into the light emitting layer 40 via the electron transport layer 80. Through the holes, holes are injected into the light emitting layer 40. In the light emitting layer 40, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. Subsequent operations are performed by the light emitting device 1000 according to the first embodiment.
It is almost the same as

Light emitting device 1003 has the same function and effect as light emitting device 1000 shown in FIG. 1, and further includes hole transport layer 70 and electron transport layer 80, thereby improving the hole and electron transport ability. Can be achieved.

FIG. 5 shows an example in which the diffraction grating 212 is provided in the electron transport layer 80. However, when the cathode 50 is formed of a material other than metal, for example, diamond, the electron transport layer 80 is formed. And the cathode 50 can form a diffraction grating. When the electron transport layer 80 is not formed, a diffraction grating can be formed by the cathode 50 and the light emitting layer 40.

(D) The light emitting device 1004 shown in FIG. 6 differs from the light emitting device portion 104 in that the light emitting element portion 104 includes the hole transport layer 170 in FIG.
Is different from the light emitting device 1000 shown in FIG. In addition, the point that the hole transport layer 170 is included in the light emitting element portion 104, the point that the second medium layer 312b forming the diffraction grating 312 is continuous with the light emitting layer 140, and the prism 121 are formed on the anode 30. In this respect, it has a configuration similar to that of the light emitting device 1001 shown in FIG. On the other hand, the light emitting device 1001 shown in FIG. 3 is different from the light emitting device 1001 shown in FIG. 3 in that the first medium layer 312a forming the diffraction grating 312 is continuous with the hole transport layer 170.

The light emitting device 1004 includes the substrate 10 and the substrate 1
0 on the light-emitting element portion 104. The light emitting element section 104 is formed by stacking the anode 30, the hole transport layer 170 and the prism 121, the light emitting layer 140, and the cathode 50 in this order. Also, the diffraction grating 3
Reference numeral 12 is formed in a boundary region between the light emitting layer 140 and the hole transport layer 170. That is, the diffraction grating 312 has the light emitting layer 1 in the groove 13 provided on the upper surface of the hole transport layer 170.
It is formed by embedding a material for forming 40. Therefore, the first medium layer 312 a constituting the diffraction grating 312 is continuous with the hole transport layer 170. Therefore, the hole transport layer 170 functions as a part of the diffraction grating 312 (first medium layer 312a). The second medium layer 312b constituting the diffraction grating 312 is the light emitting layer 1
Continue to 40. Therefore, the light emitting layer 140 functions as a part of the diffraction grating 312 (the second medium layer 312b).

The operation, operation, and effect of the light emitting device 1004 are the same as those of the light emitting device 1001 shown in FIG.

(E) The light emitting device 1005 shown in FIG. 7 differs from the light emitting devices 1000 to 1004 in that the diffraction grating 412 has a refractive index distribution type structure. Further, the light emitting device 1005 includes the hole transport layer 70 in the light emitting element portion 105.
The light emitting device 1001 has the same configuration as the light emitting device 1001 shown in FIG. On the other hand, it differs from the light emitting device 1001 shown in FIG. 3 in that the diffraction grating 412 is formed on the substrate 10 and the prism 31 is formed on the insulator 60.

The light emitting device 1005 comprises a substrate 10 and a substrate 1
0 formed on the light emitting element portion 105. The light emitting element section 105 includes the insulating layer 60, the anode 30, and the prism 3
1. The hole transport layer 70, the light emitting layer 40, and the cathode 50 are formed by stacking in this order.

The diffraction grating 412 is formed on the first medium layer 4.
12a and the second medium layer 412b, and has a refractive index coupling type structure. The first medium layer 412a is
First medium layer 12a constituting diffraction grating 12 shown in FIG.
It is formed of the same material as. The second medium layer 412b is continuous with the insulating layer 60. That is, the insulating layer 60 functions as a part of the diffraction grating 412 (the second medium layer 412b).

The operation, operation, and effects of the light emitting device 1005 are almost the same as those of the light emitting device 1001 shown in FIG.

[Second Embodiment] (Structure of Device) FIG. 8 is a sectional view schematically showing a light emitting device 2000 according to the present embodiment.

The light emitting device 2000 comprises a substrate 10 and a substrate 1
0 on the light-emitting element portion 200. In the light emitting device 2000, the light emitting element unit 200 includes the anode 30, the light emitting layer 4
The light emitting device 1000 according to the first embodiment is the same as the light emitting device 1000 according to the first embodiment in that the light emitting device 1000 includes 0, the cathode 50, and the diffraction grating 12. On the other hand, the light emitting device 2000 is different from the first embodiment in that a diffraction grating 20 different from the diffraction grating 12 is formed on the substrate 10 instead of the prism 11 as a member for changing the propagation direction of light. Different from the light emitting device 1000 according to the embodiment.

The diffraction grating 20 is set so that the pitch in the periodic direction is (a + 1) λ / 2n (a is an integer of 1 or more, and n is the average refractive index). Here, the order of the diffraction grating is (a + 1) order. Therefore, diffraction grating 2
0 is a diffraction grating of the second order or higher. In the present embodiment, the diffraction grating 20 is a second-order diffraction grating, and its pitch in the periodic direction is λ / n, as shown in FIG.
It is formed so that it becomes.

When the diffraction grating 20 is of the second order or higher,
The light incident on the diffraction grating 20 is emitted not only in the plane direction of the substrate 10 (X direction) but also in the direction intersecting with the substrate 10 (Y direction). In particular, as shown in FIG. 2, when the diffraction grating 12 is of the second order, the substrate 10 is in the plane direction (X direction shown in FIG. 1) and the film thickness direction of the substrate 10 (Y direction shown in FIG. 1). Light is also emitted to The order of the diffraction grating 12 can be set by setting the pitch of the diffraction grating 12 in the periodic direction to a predetermined value based on the above-described formula.

In this embodiment, the case where the diffraction grating 20 is a second-order diffraction grating has been described. However, the diffraction grating 20 is not limited to the second-order diffraction grating, and is not limited to the second-order diffraction grating. Any diffraction grating of the order or more may be used. The order of the diffraction grating 20 can be set by setting the pitch of the diffraction grating 20 in the periodic direction to a predetermined value based on the equation shown in the first embodiment. By appropriately selecting the pitch of the diffraction grating 20, the diffraction grating 2
By setting the order of 0, light can be propagated in an arbitrary direction. The location of the diffraction grating 20 can be set as appropriate.

(Operation of Device) Next, the light emitting device 2
000 will be described.

When a predetermined voltage is applied to the anode 30 and the cathode 50, electrons are injected from the cathode 50 and holes are injected from the anode 30 into the light emitting layer 40, respectively. In the light emitting layer 40, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. The light generated in the light emitting layer 40 is distributed-propagation-type propagated by the diffraction grating 12, and is emitted from the substrate 10 in the plane direction (X direction). Here, as a result of a part of the light generated in the light emitting layer 40 being incident on the diffraction grating 20 of the second order, the direction in which the light propagates in a direction substantially perpendicular to the surface of the substrate 10 (Y direction) is changed. And then exit.

(Operation and Effect) The light emitting device 2000 according to the present embodiment has the same operation and effect as the light emitting device 1000 according to the first embodiment. That is, according to the light emitting device 2000, the light emitting element unit 200 includes the diffraction grating 20, so that the direction in which a part of the light generated in the light emitting layer 40 propagates by the diffraction grating 20 is changed. In addition to the surface direction,
Control is performed so that light is emitted also in the direction intersecting zero.

[Third Embodiment] (Structure of Device) FIG. 9 is a sectional view schematically showing a light emitting device 3000 according to the present embodiment, and FIG.
10A is a cross-sectional view taken along the line BB in FIG. 9, and FIGS. 10B and 10C are FIGS.
It is a figure showing a modification of diffraction grating 22 shown in (a).

Light emitting device 3000 includes diffraction grating 12 having a periodic refractive index distribution in one direction, in that diffraction grating 22 has a periodic refractive index distribution in the first, second, and third directions. This is different from the light emitting device 1000 (the first embodiment). The other components are substantially the same as those of the light emitting device 1000 according to the first embodiment, and thus the description of the components will be omitted. In FIG. 10A, the prism 11 (see FIG. 9) is omitted, and the diffraction grating 2
2, only the first and second medium layers 22a and 22b are shown.

The diffraction grating 22 has the first,
It has a periodic refractive index distribution in the second and third directions. That is, in the diffraction grating 22, as shown in FIG. 10A, the first medium layers 22a having different refractive indexes are arranged in a triangular lattice shape. The first medium layer 22a has a columnar shape,
The second medium layer 22b is disposed between the first medium layers 22b. In addition, the second medium layer 22b includes the light emitting layer 40 like the second medium layer 22b according to the first embodiment.
It is continuous.

Further, the light emitting device 30 according to the present embodiment
00, the pitch in the periodic direction of the diffraction grating 22 is λ
/ 2n (n is the average refractive index). Therefore, the diffraction grating 22 is a first-order diffraction grating. Note that FIG.
As shown in (a) of (a), the diffraction grating 22 has a, b,
And a periodic refractive index distribution in the c direction, the pitch is set such that the distance between the centers of the first medium layers 22a adjacent to each other is λ / 2n. In addition, FIG.
As shown in (2) of (a), the diffraction grating 22 has a ″,
When the refractive index distribution has a periodic refractive index distribution in the b ″ and c ″ directions, the pitch is such that the distance between the centers of the adjacent first medium layers 22a is λ / 2n.

The diffraction grating 22 is a first-order diffraction grating, like the diffraction grating 12 according to the first embodiment.

A modification of the diffraction grating 22 is shown in FIG.
(B) and FIG. 10 (c). FIG. 10B shows an example in which the first medium layers 22a shown in FIG. 10A are arranged in a square lattice. In this case, it has a periodic refractive index distribution in the first and second directions (a ′ and b ′ directions). In (2) of FIG. 10A and FIG. 10B, the pitch in the periodic direction of the diffraction grating 22 refers to the distance between the centers of the adjacent first medium layers 22a.

FIG. 10C shows an example in which the first medium layer 22a in FIG. 10A is arranged in a honeycomb shape.

In both cases shown in FIGS. 10B and 10C, the diffraction grating 22 is a first-order diffraction grating. Further, in FIG.
The distance between the centers of the medium layers 22a is λ / 2n. FIG.
In 0 (c), the distance between the centers of the first medium layers 22a adjacent to each other is λ / 2n.

(Operation of Device) This light emitting device 3000
Is similar to that of the light emitting device 1000 shown in FIG.

(Operation and Effect) The light emitting device 3000
In addition to having the same operation and effect as the light emitting device 1000 according to the first embodiment, the light emitting device 3000
Since the diffraction grating 22 has a periodic refractive index distribution in the first, second, and third directions, propagation of light in the three directions is restricted. Therefore, the light emitting device 1000 according to the first embodiment that restricts light propagation in only one direction.
Since the propagation of light is more restricted than it is, light with a very narrow emission spectrum width can be obtained with high efficiency. In this case, it is preferable that the planar structure of the prism 11 be circular or the like (a diffraction grating is provided in the central opening).

Even in the case where the diffraction gratings shown in FIGS. 10B and 10C are included, almost the same operations and effects as those described above are obtained.

[Fourth Embodiment] (Structure of Device) FIG. 11 is a sectional view schematically showing a light emitting device 4000 according to this embodiment.

Light emitting device 4000 includes first and second dielectric multilayer films 90a and 90b in light emitting element section 400.
As shown in FIG. 11, a first dielectric multilayer film 90a, an anode 30, a prism 11, a diffraction grating 1
2, the light emitting layer 40, the cathode 50, and the second dielectric multilayer film 90b are arranged in this order. That is, between the substrate 10 and the anode 30 and on the surface of the cathode 50 opposite to the surface on which the light emitting layer 40 is formed,
First and second dielectric multilayer films 90a and 90b are formed. In FIG. 11, the first and second dielectric multilayer films 90a and 90b are emphasized. The components other than the first and second dielectric multilayer films 90a and 90b are substantially the same as those of the light emitting device 1000 according to the first embodiment, and the description of the components will be omitted.

(Operation of Device) This light emitting device 4000
Is almost the same as that of the light emitting device 1000 shown in FIG. That is, when a predetermined voltage is applied to the anode 30 and the cathode 50, electrons are injected from the cathode 50 and holes are injected from the anode 30 into the light emitting layer 40, respectively. In the light emitting layer 40, the electrons and holes are recombined to generate excitons, and when the excitons are deactivated, light such as fluorescence or phosphorescence is generated. Direction). In this case, the direction in which some of the light propagating in the surface direction of the substrate 10 propagates by the prism 11 can be emitted in a direction crossing the substrate 10.

(Operation and Effect) Light propagation in the Y direction in FIG. 11 is controlled by the first and second dielectric multilayer films 90a and 90b. That is, the light in the thickness direction of the substrate 10 can be controlled by the first and second dielectric multilayer films 90a and 90b. In the present embodiment, in addition to the diffraction grating 12, the first and second dielectric multilayer films 90a,
90b controls the propagation of light and restricts spontaneous emission, so that light with a very narrow emission spectrum width can be obtained with high efficiency even in the thickness direction of the substrate 10.

In this embodiment, the anode 30 and the cathode 5
0, the first and second dielectric multilayer films 90a, 90
The example in which the “b” is formed is shown.
The layer is not limited to 0a and 90b, but may be any layer having a large reflectance.

When the light emitting device of the present invention is used in, for example, a display, it is necessary to emit light toward the substrate 10 in order to improve light use efficiency. In this case, in the light emitting device 4000 according to the present embodiment, since the dielectric multilayer film 90b is formed on the cathode 50, light emitted toward the cathode 50 can be reflected by the dielectric multilayer film 90b. For this reason, light emitted from the cathode 50 side can be reduced and light can be emitted preferentially from the substrate 10 side, so that light use efficiency can be increased.

In this case, it is desirable that the phase of the light reflected on the cathode 50 side and the phase of the light directly emitted on the substrate 10 side be matched.

In the light emitting device 4000, a CuPc layer (Copper ph) is used instead of the cathode 50 made of a metal material.
thalocyanine) can also be used. In this case,
A layer made of ITO is provided between the CuPc layer and the dielectric multilayer film 90b.

The diffraction grating 12 is similar to the diffraction grating 12 formed in the light emitting device 1000 according to the first embodiment, but is different from the diffraction grating 12 formed in the light emitting device 3000 according to the third embodiment. Lattice 22 (FIGS. 10A to 10C)
The same thing as described above can be used.

[Fifth Embodiment] (Structure of Device) FIG. 12 is a sectional view schematically showing a light emitting device 5000 according to this embodiment, and FIG.
FIG. 13 is a sectional view taken along line CC in FIG. The light emitting device 5000 is different from the above light emitting device in having a distributed Bragg reflection type diffraction grating.

The light emitting device 5000 comprises a substrate 10 and a substrate 1
0 on the light-emitting element portion 500. The light emitting element unit 500 includes the anode 30, the prism 11, and the light emitting layer 40.
The cathode 50 is formed by being stacked in this order.

The diffraction grating 32 is formed in the boundary region between the cathode 30 and the light emitting layer 40, and forms a distributed Bragg type diffraction grating. Thus, the distributed Bragg type diffraction grating 32
Is formed, the light resonates, and light having excellent wavelength selectivity and directivity can be obtained.

(Operation, Function and Effect of Device) The operation, function and effect of the light emitting device 5000 are almost the same as those of the light emitting device 1000 shown in FIG.

[Sixth Embodiment] (Structure of Device) FIG. 14 is a sectional view schematically showing a light emitting device 6000 according to the present embodiment, and FIG.
FIG. 15 is a sectional view taken along line DD in FIG. 14. The light emitting device 6000 differs from the light emitting devices according to the above-described first to fifth embodiments in that the diffraction grating 42 includes the defective portion 14.

The light emitting device 6000 comprises a substrate 10 and a substrate 1
0 on the light-emitting element portion 600. The light emitting element section 600 includes the anode 30, the prism 11, and the light emitting layer 4.
0, the cathode 50 and the diffraction grating 42. Note that, among these components, those having the same reference numerals are the same as the components of the light emitting device 1000 according to the first embodiment, and thus description thereof will be omitted.

Light emitting device 6000 according to this embodiment
Includes a diffraction grating 42 in which the defective portion 14 is formed.

The diffraction grating 42 is similar to the diffraction grating 12 of the light emitting device 1000 according to the first embodiment in that it has a periodic refractive index distribution in one direction. That is, the diffraction grating 42 is configured by alternately arranging the first medium layers 42a and the second medium layers 42b having different refractive indexes.

Further, similarly to the diffraction grating 12 of the light emitting device 1000 according to the first embodiment, the diffraction grating 42 has a pitch in the periodic direction of λ / 2n (a
= 1). Therefore, the diffraction grating 42 has the first order.

As in the diffraction grating 12 of the light emitting device 1000 according to the first embodiment, the diffraction grating 42 has first medium layers 42a and second medium layers 42b having different refractive indexes alternately arranged. And the light emitting layer 40 has a diffraction grating 42
(The second medium layer 42b).

Further, the diffraction grating 42 includes the defect portion 14.
A first medium layer 42a is formed on both sides of the defect portion 14. The diffraction grating 42 can form a photonic band gap for a predetermined wavelength band based on a combination of a shape (dimension) and a medium.

The defect portion 14 is formed such that the energy level caused by the defect exists in the emission spectrum of the light emitting layer 40 due to current excitation.

In the present embodiment, the defect 14
Has been shown to be formed of the same material as the first medium layer 42a constituting the diffraction grating 42, but the first medium layer 42a
May be a substance capable of forming a photonic band gap by a periodic distribution with the second medium 42b.
The material is not particularly limited. For example, the second medium layer may be a gas such as air. As described above, in the case of forming a diffraction grating having a so-called air gap structure using a gas layer, it is necessary to increase the difference between the refractive indices of the two media constituting the diffraction grating within the range of selecting a general material used for the light emitting device. Can be.

Further, the defective portion 14 is formed in the second medium layer 42b.
May be formed. For example, in the light emitting device 6000 shown in FIG. 14, instead of providing the defective portion 14, a defect can be formed by embedding the light emitting layer 40 in a region where the defective portion 14 is formed. In this case, the light emitting layer 40 functions as a part of the defective part.

In the light emitting device 6000 of the present embodiment, the prism 11 is formed, so that the surface direction of the diffraction grating 12 (X direction in FIG. 1) is similar to the light emitting device 1000 of the first embodiment. In addition, light propagation in both the film thickness direction of the substrate 10 (the Y direction in FIG. 1) is controlled.

It is to be noted that not only the light emitting device 6000 of the present embodiment but also the light emitting device according to a modification of the first embodiment (see FIGS. 3 to 7) and the light emitting device of the second to fifth embodiments In such a light emitting device (see FIGS. 9 to 13), a light emitting device can also be formed by forming a diffraction grating including a defect part in a part thereof.

For example, the light emitting device 1002 shown in FIG.
In addition, a defect can be provided in the diffraction grating. In this case, since the hole transport layer 70 functions as a part of the diffraction grating, the light emitting layer 40 is formed in a region different from the diffraction grating.

(Operation, Function and Effect of Device) Next, the operation, function and effect of the light emitting device 6000 will be described.

When a predetermined voltage is applied to the anode 30 and the cathode 50, electrons are injected from the cathode 50 and holes are injected from the anode 30 into the light emitting layer 40, respectively. In the light emitting layer 40, the electrons and holes are recombined to generate excitons. Since light in a wavelength band corresponding to the photonic band gap of the diffraction grating 42 cannot propagate through the diffraction grating 42, the exciton returns to the ground state at the energy level caused by the defect, and this energy level Only light of the corresponding wavelength band is generated. This light propagates through the substrate 10 in the plane direction (X direction), and the prism 1
As a result, the direction of propagation is changed and the substrate 10
Light is emitted in a direction (Y direction) substantially perpendicular to the surface. As described above, light with a very narrow emission spectrum width defined by the energy level caused by the defect can be obtained with high efficiency and can be emitted in a direction crossing the substrate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a light emitting device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view schematically showing a modified example of the light emitting device according to the first embodiment.

FIG. 4 is a sectional view schematically showing a modified example of the light emitting device according to the first embodiment.

FIG. 5 is a sectional view schematically showing a modification of the light emitting device according to the first embodiment.

FIG. 6 is a sectional view schematically showing a modified example of the light emitting device according to the first embodiment.

FIG. 7 is a sectional view schematically showing a modified example of the light emitting device according to the first embodiment.

FIG. 8 is a cross-sectional view schematically showing a light emitting device according to a second embodiment of the present invention.

FIG. 9 is a sectional view schematically showing a light emitting device according to a third embodiment of the present invention.

FIG. 10 is a sectional view taken along line BB of FIG. 9;

FIG. 11 is a sectional view schematically showing a light emitting device according to a fourth embodiment of the present invention.

FIG. 12 is a sectional view schematically showing a light emitting device according to a fifth embodiment of the present invention.

FIG. 13 is a sectional view taken along line CC of FIG. 12;

FIG. 14 is a sectional view schematically showing a light emitting device according to a sixth embodiment of the present invention.

FIG. 15 is a sectional view taken along line DD of FIG. 14;

[Explanation of symbols]

10 Substrate 11, 21, 31, 121 Prism 12, 22, 32, 42, 112, 212, 312, 4
12 diffraction grating 12a, 22a, 32a, 42a, 112a, 212
a, 312a, 412a First medium layer 12b, 22b, 32b, 42b, 112b, 212
b, 312b, 412b Second medium layer 13 Groove 14 Defect portion 20 Diffraction grating 30 Anode 40, 140 Light emitting layer 50 Cathode 60 Insulator 70, 170 Hole transport layer 80 Electron transport layer 90a First dielectric multilayer film 90b 2 dielectric multilayer film 100, 101, 102, 103, 104, 105, 2
00, 300, 400, 500, 600 Light emitting element section 1000, 1001, 1002, 1003, 1004
1005, 2000, 3000, 4000, 5000,
6000 EL device

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2H049 AA06 AA33 AA37 AA40 AA43 AA48 AA50 AA52 AA60 AA64 3K007 AB02 AB04 BA00 CA01 DA01 DB03 EA00 EB00

Claims (28)

[Claims] 1. A light-emitting element comprising: a substrate; and a light-emitting element formed on the substrate, wherein the light-emitting element includes a light-emitting layer capable of emitting light by electroluminescence, and a pair of a light-emitting layer for applying an electric field to the light-emitting layer. A light emitting device comprising: an electrode layer; a diffraction grating; and a member for changing a direction in which light propagates. 2. The device according to claim 1, wherein light is propagated in a plane direction of the substrate by the diffraction grating, and a direction in which at least a part of light propagated in a plane direction of the substrate is propagated by the member. A light emitting device that emits the light in a direction intersecting the substrate by changing 3. The light emitting device according to claim 1, wherein the member is a prism. 4. The light emitting device according to claim 1, wherein the member is a diffraction grating of second order or higher. 5. The diffraction grating according to claim 4, wherein the diffraction grating of the second order or higher constituting the member has a pitch in the period direction of (a + 1) λ / 2n (a is an integer of 1 or more, and n is an average refractive index). A light emitting device. 6. The light emitting device according to claim 1, wherein the member is formed on at least one of the light emitting layer and the electrode layer. 7. The light-emitting device according to claim 1, wherein the diffraction grating can form a photonic band gap or an incomplete photonic band. 8. The diffraction method according to claim 1, wherein an energy level of an emission spectrum of the light emitting layer includes an energy level of a band edge included in a band formed by the diffraction grating. A light emitting device in which a lattice is formed. 9. The light emitting device according to claim 8, further comprising a defect portion formed in a part of the diffraction grating and set such that an energy level caused by the defect exists in a predetermined emission spectrum. 10. The light emitting device according to claim 1, wherein the diffraction grating is a distributed feedback type diffraction grating. 11. The light emitting device according to claim 1, wherein the diffraction grating is a distributed Bragg reflection type diffraction grating. 12. The light emitting device according to claim 1, wherein the diffraction grating has a gain coupling type structure. 13. The light emitting device according to claim 1, wherein the diffraction grating has a refractive index coupling type structure. 14. The light emitting device according to claim 1, wherein the light emitting layer includes an organic light emitting material as a light emitting material. 15. The light-emitting device according to claim 1, wherein the light-emitting layer functions as at least a part of the diffraction grating. 16. The light emitting device according to claim 7, wherein the light emitting layer functions as at least a part of the defect. 17. The light emitting device according to claim 1, wherein the light emitting layer is formed in a region different from the diffraction grating. 18. The light emitting device according to claim 1, further comprising at least one of a hole transport layer and an electron transport layer. 19. The light-emitting device according to claim 18, wherein the hole transport layer or the electron transport layer of the diffraction grating forms one medium. 20. The light emitting device according to claim 18, wherein the member is formed on at least one of the hole transport layer and the electron transport layer. 21. The light emitting device according to claim 1, wherein the diffraction grating has an insulating first medium layer and a second medium layer that are periodically arranged. 22. The method according to claim 21, wherein the first medium layer has a columnar shape and is arranged in a lattice, and the second medium layer is disposed between the first medium layers. Light emitting device. 23. The light emitting device according to claim 21, wherein the diffraction grating has a periodic refractive index distribution in at least one direction. 24. The light emitting device according to claim 21, wherein the diffraction grating has a periodic refractive index distribution in first and second directions. 25. The light emitting device according to claim 21, wherein the diffraction grating has a periodic refractive index distribution in first, second, and third directions. 26. The light emitting device according to claim 1, wherein a layer that regulates the propagation of the light is provided on at least one of the electrode layers. 27. The light emitting device according to claim 26, wherein the layer that regulates light propagation is a clad layer or a dielectric multilayer film. 28. The light emitting device according to claim 1, which is used for a display.