JP2006338954A - Organic led element, organic led display device and substrate for organic led display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic LED element and an organic LED display device having a small chromaticity change depending on a view angle; and to provide a substrate for an organic LED display device suitable for the organic LED display device. <P>SOLUTION: This organic LED display device 1 includes this organic LED element 7 formed by stacking, on a transparent substrate 2 with a dielectric film 3 formed thereon, a positive electrode 4 being a transparent electrode, an organic layer 5, and a negative electrode 6 in that order. The film thickness of the dielectric layer 3 is not smaller than 0.5 μm; and, in a wavelength region of 450 to 650 nm, relationships of ¾n<SB>3</SB>-n<SB>2</SB>¾≤0.25 and ¾n<SB>1</SB>-n<SB>2</SB>¾≤0.2 are established among reflectivity n<SB>1</SB>of the organic layer 5, reflectivity n<SB>2</SB>of the positive electrode 4 and reflectivity n<SB>3</SB>of the dielectric film 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic LED (Light-Emitting Diode) element, an organic LED display device, and a substrate for an organic LED display device.

  The organic LED element is also referred to as an organic EL (Electro Luminescence) element, and is an element that utilizes a phenomenon in which light is emitted by excitons generated by recombination of electrons and holes injected into an organic substance.

  In recent years, displays using this organic LED element have been actively developed. This is because the organic LED display has a wide viewing angle, a fast response speed, a high contrast, and the like as compared with the liquid crystal display.

  In general, an organic LED element has a structure in which an organic film is sandwiched between a transparent conductive film and a metal electrode, and light emitted inside the element is extracted outside the element through the transparent electrode. Here, the emitted light is emitted with an intensity equal to all directions inside the element. That is, light having the same intensity as the light emitted in front of the element is also emitted in the direction of the back surface of the element. Therefore, in order to increase the amount of light extracted to the outside, it is necessary to reflect the light radiated on the back surface forward and to extract it efficiently.

  However, the light traveling directly in front of the element and the light reflected back to the front interfere with each other. In addition, since there is a difference in refractive index between members constituting each layer, light is reflected also at the interface. This will be described with reference to FIG.

  FIG. 39 is a schematic cross-sectional view of a conventional organic LED display device. As shown in the figure, an organic LED display device 91 is formed by laminating an ITO (Indium Tin Oxide) 93 as an anode, an organic film 94, and an aluminum film 95 as a cathode in this order on a glass substrate 92. The organic LED element 96 is provided. Here, the refractive index of the glass substrate 92 is about 1.55, the refractive index of the organic film 94 is about 1.8, and the refractive index of ITO 93 is about 1.9.

  The organic LED display 91 is provided with a sealing member 97 for sealing the organic LED element 96 on the glass substrate 92. In FIG. 39, reference numeral 98 denotes a power source that applies a driving voltage to the organic LED element 96.

  When a voltage is applied to the organic LED element 96, electrons are injected as carriers from the cathode and holes are injected from the anode, respectively. These carriers are recombined inside the organic film 94, and light is emitted by excitons generated thereby.

  The light emitted from the light emitting region is reflected by the aluminum film 95 after going to the back direction (upward in the drawing) in addition to the light 99 going to the front (downward in the drawing) of the organic LED display device 91. There is also light 100 that travels forward after being done.

  In addition, since there is a large refractive index step at the interface between the glass substrate 92 and the ITO 93, the light is reflected forward by the glass substrate 92 after being directed forward, and further reflected by the aluminum film 95 after being reflected by the aluminum film 95 again. There is also light 101 going forward.

  Similarly, there is also light 102 that is reflected in the order of the aluminum film 95, the glass substrate 92, and the aluminum film 95 after going in the back direction.

  Since these lights (99, 100, 101, 102) interfere with each other, there is a problem that the chromaticity changes depending on the viewing angle.

  Conventionally, for such problems, the phase difference between the reflected light of the front radiated light and the back radiated light satisfies the conditions for strengthening optical interference with respect to the film thickness of each film constituting the organic LED element. Optimization is performed (for example, refer nonpatent literature 1).

For example, when the optical distance from the light emitting region to the cathode reflecting surface is L ₁ and the distance from the anode reflecting surface is L ₂ , the conditions for strengthening interference with light of wavelength λ are as follows:
L ₁ = {(2m + 1) / 4} λ
L ₂ = {(m + 1) / 2} λ
(However, m = 0, 1, ...)
It becomes. Therefore, the emission spectrum affected by the optical interference and L ₂ where the external quantum efficiency is optimal are obtained, and the film thickness balance between the organic film (hole injection layer and hole transport layer) constituting the L ₂ and ITO. By adjusting, the light extracted outside the organic LED element can be increased.

  On the other hand, due to the difference in refractive index between the protective layer that protects the organic LED element from water and oxygen and the members above and below the protective layer, the light is reflected at these interfaces and the amount of emitted light is reduced. In order to achieve this, a method of changing the refractive index of the protective layer from the upper layer toward the lower layer has been proposed (see, for example, Patent Document 1).

For example, when passing through the interface of the light of the two layers of different refractive index materials, the reflectance at the interface R is the refractive index of each layer respectively and n _a and n _{b,
^{R = (n a -n b)}} 2 / (n a + n b) 2
It is represented by Accordingly, as the difference between the refractive index n _a and n _b is reduced, the refractive index R becomes smaller, the intensity of light transmitted through the interface is increased.

Satoshi Miyaguchi, 6 others, “Development of organic EL full-color display”, Pioneer R & D, Volume 11, No. 1, p. 21-28 JP 2003-133062 A

  However, in the method of optimizing the film thickness so as to satisfy the conditions for strengthening optical interference, it is necessary to strictly control the film thickness according to the refractive index for each film. On the other hand, the demand for viewing angle dependency of chromaticity tends to increase, and there is a limit to deal with this by only optimizing the film thickness.

  Further, the method of continuously changing the refractive index of the protective layer has a problem that it is not easy to form such a protective layer.

  The present invention has been made in view of such problems. That is, an object of the present invention is to provide an organic LED element in which a chromaticity change due to a viewing angle is reduced by a simple method.

  Another object of the present invention is to provide an organic LED display device having a small change in chromaticity depending on the viewing angle.

  Furthermore, the objective of this invention is providing the board | substrate suitable for the organic LED display device with a small chromaticity change by a viewing angle.

  Other objects and advantages of the present invention will become apparent from the following description.

In the first aspect of the present application, in an organic LED element including an organic layer sandwiched between an anode and a cathode, at least one of the anode and the cathode is a transparent electrode, and a dielectric layer in contact with the transparent electrode on the side opposite to the organic layer the have a thickness of the dielectric layer is not 0.5μm or more, in the wavelength region of 450 nm to 650 nm, the refractive index of the refractive index _{n 2} and the dielectric film having a refractive index _{n 1,} the transparent electrode of the organic layer n ₃ at least | n ₃ −n ₂ | ≦ 0.25
And | n ₁ −n ₂ | ≦ 0.20
It is related with the organic LED element characterized by these relationships being materialized.

  In the first aspect of the present application, the thickness of the dielectric layer can be not less than 0.5 μm and not more than 2.0 μm. In particular, the thickness of the dielectric layer is preferably 1.0 μm or more and 2.0 μm or less.

Further, in the first aspect of the present application, in the wavelength region of 450 nm to 650 nm, the refractive index n ₁ of the organic layer, the refractive index n _{2 of the} transparent electrode, and the refractive index n ₃ of the dielectric film,
| N ₃ −n ₂ | ≦ 0.20
And | n ₁ −n ₂ | ≦ 0.20
It is more preferable that the relationship is established.

In the first aspect of the present application, the dielectric film may be composed of at least two elements selected from the group consisting of silicon, oxygen, nitrogen, and aluminum. In particular, the dielectric film is any one film selected from the group consisting of SiO _x film, Si _x N _y film, AlN _x film, SiO _x N _y film, AlO _x N _y film, and SiAlO _x N _y film. Preferably there is. In the first aspect of the present application, the organic layer can emit white light.

The second aspect of the present application is a transparent substrate, a dielectric film provided on the transparent substrate, an anode made of a transparent conductive material provided on the dielectric film, and a metal having a small work function, or An organic LED element in which an organic layer is sandwiched between a cathode made of a metal alloy and a sealing member that is provided on a transparent substrate and seals the organic LED element. The thickness of the dielectric layer is 0 In the wavelength region of 450 nm to 650 nm, between the refractive index n ₁ of the organic layer, the refractive index n _{2 of the} anode, and the refractive index n ₃ of the dielectric film,
| N ₃ −n ₂ | ≦ 0.25
And | n ₁ −n ₂ | ≦ 0.20
It is related with the organic LED display device characterized by these relationships being materialized.

The third aspect of the present application is an organic LED element provided on an opaque substrate, an opaque substrate, and an organic layer sandwiched between an anode and a cathode made of a transparent conductive material, and a dielectric provided on the cathode A transparent sealing member that is provided on an opaque substrate and seals the organic LED element and the dielectric film, the thickness of the dielectric layer is 0.5 μm or more, and is 450 nm to 650 nm in the wavelength range, the refractive index _{n 1} of the organic layer, between the refractive index _{n 3} of the refractive index _{n 2} and the dielectric film of the cathode, at least _| n 3 -n _{2 |} ≦ 0.25
And | n ₁ −n ₂ | ≦ 0.20
It is related with the organic LED display device characterized by these relationships being materialized.

  In the second aspect and the third aspect of the present application, the thickness of the dielectric layer is preferably 0.5 μm or more and 2.0 μm or less. In particular, the thickness of the dielectric layer is preferably 1.0 μm or more and 2.0 μm or less.

Further, the present application in a second aspect and the third aspect of the embodiment, in the wavelength region of 450 nm to 650 nm, the refractive index _{n 1} of the organic layer, between the refractive index _{n 3} of the refractive index _{n 2} and the dielectric film of the transparent electrode ,
| N ₃ −n ₂ | ≦ 0.20
And | n ₁ −n ₂ | ≦ 0.20
It is more preferable that the relationship is established.

In the second aspect and the third aspect of the present application, the dielectric film may be composed of at least two elements selected from the group consisting of silicon, oxygen, nitrogen, and aluminum. In particular, the dielectric film is any one film selected from the group consisting of SiO _x film, Si _x N _y film, AlN _x film, SiO _x N _y film, AlO _x N _y film, and SiAlO _x N _y film. Preferably there is. The organic layer can emit white light.

The fourth aspect of the present application includes a transparent substrate, a dielectric film having a thickness of 0.5 μm or more provided on the transparent substrate, and a transparent electrode film provided on the dielectric film, in the wavelength range of 450 nm to 650 nm, between the refractive index _{n b} of the refractive index _{n a} and the transparent electrode film of the dielectric film,
| N _a −n _b | ≦ 0.25
It is related with the board | substrate for organic LED display apparatuses characterized by these relationships being materialized.

  In the fourth aspect of the present application, the thickness of the dielectric layer is preferably 0.5 μm or more and 2.0 μm or less. In particular, the thickness of the dielectric layer is preferably 1.0 μm or more and 2.0 μm or less.

Further, the present application In a fourth aspect, in the wavelength region of 450 nm to 650 nm, between the refractive index _{n b} of the refractive index _{n a} and the transparent electrode film of the dielectric film,
| N _a −n _b | ≦ 0.20
It is more preferable that the relationship is established.

In the fourth aspect of the present application, the dielectric film may be composed of at least two elements selected from the group consisting of silicon, oxygen, nitrogen, and aluminum. In particular, the dielectric film is any one film selected from the group consisting of SiO _x film, Si _x N _y film, AlN _x film, SiO _x N _y film, AlO _x N _y film, and SiAlO _x N _y film. Preferably there is.

  According to the first aspect of the present application, by providing the dielectric layer in contact with the transparent electrode on the side opposite to the organic layer, an organic LED element having a small change in chromaticity depending on the viewing angle can be obtained.

  In addition, according to the second aspect of the present application, an organic LED display device having excellent viewing angle dependency of chromaticity can be obtained by providing a dielectric film between the transparent substrate and the anode.

  Moreover, according to the third aspect of the present application, an organic LED display device having excellent viewing angle dependency of chromaticity can be obtained by providing a dielectric film on the cathode.

  Furthermore, according to the fourth aspect of the present application, by providing a dielectric film between the substrate and the transparent electrode film, a substrate suitable for an organic LED display device having a small change in chromaticity due to a viewing angle can be obtained.

  As a result of diligent research, the present inventor has found that in an organic LED element having an organic layer sandwiched between an anode and a cathode, at least one of the anode and the cathode is a transparent electrode, and a dielectric that is in contact with the transparent electrode on the side opposite to the organic layer. It has been found that the chromaticity change due to the viewing angle can be reduced by providing the body layer.

However, the thickness of the dielectric layer is 0.5 μm or more, and in the wavelength region of 450 nm to 650 nm, the refractive index of the organic layer is n ₁ , the refractive index of the transparent electrode is n ₂ , and the refractive index of the dielectric film When the the _{n 3,} at least _{| n 3 -n 2 | ≦ 0.25} , and _| n 1 -n _{2 |} ≦ 0.20
It is necessary to establish the relationship.

  For example, in the above organic LED element, when the anode is a transparent electrode and emitted light is extracted from the anode, the following relationship needs to be established.

That is, the film thickness of the dielectric layer needs to be 0.5 μm or more. Further, in the wavelength region of 450 nm to 650 nm, the refractive index _{n 1} of the organic layer, between the refractive index _{n 3} of the refractive index _{n 2} and the dielectric film of the transparent electrode (anode),
| N ₃ −n ₂ | ≦ 0.25 and | n ₁ −n ₂ | ≦ 0.20
It is necessary to establish the relationship.

  In the above organic LED element, when the cathode is a transparent electrode and emitted light is extracted from the cathode, at least the following relationship needs to be satisfied.

That is, the film thickness of the dielectric film needs to be 0.5 μm or more. Further, in the wavelength region of 450 nm to 650 nm, the refractive index _{n 1} of the organic layer, between the refractive index _{n 3} of the refractive index _{n 2} and the dielectric film of the transparent electrode (cathode),
| N ₃ −n ₂ | ≦ 0.25 and | n ₁ −n ₂ | ≦ 0.20
It is necessary to establish the relationship.

  Furthermore, when the anode and the cathode are transparent electrodes and the emitted light is extracted from both electrodes, it is necessary that the above relationship be established for each of the anode and the cathode.

The inventor has a transparent substrate, a dielectric film having a thickness of 0.5 μm or more provided on the transparent substrate, and a transparent electrode film provided on the dielectric film, in the wavelength range of 450 nm to 650 nm, between the refractive index _{n b} of the refractive index _{n a} and the transparent electrode film of the dielectric film,
| N _a −n _b | ≦ 0.25
It has been found that an organic LED display device having a small change in chromaticity depending on the viewing angle can be provided by using a substrate for an organic LED display device that satisfies the above relationship.

  In the above organic LED display substrate, the organic layer formed on the transparent electrode film and the other electrode film provided on the organic layer so as to face the transparent electrode film are suitable for the organic LED display device. Materials are used. In particular, an organic layer having a refractive index difference from the transparent electrode of less than 0.20 is suitable.

  Hereinafter, the organic LED display element and the organic LED display device substrate of the present invention will be described in more detail, and the organic LED display device of the present invention will also be described. In this specification, “transparent” means high transmittance for visible light, and the dielectric film is a film made of a transparent material.

  FIG. 1 is a schematic cross-sectional view of a first organic LED display device in the present embodiment.

  As shown in FIG. 1, the organic LED display device 1 includes an anode 4, an organic layer 5, and a cathode 6 that are laminated in this order on a transparent substrate 2 via a dielectric film 3. The organic LED element 7 is included. The organic LED element 7 is sealed by a sealing member 8 provided on the transparent substrate 2. The sealing member 8 is fixed to the transparent substrate 2 via, for example, an adhesive. In FIG. 1, reference numeral 9 denotes a power source that applies a driving voltage to the organic LED element 7.

  In FIG. 1, the substrate for an organic LED display device according to the present invention includes a transparent substrate 2, a dielectric film 3 and an anode 4. Here, in FIG. 1, the anode 4 is formed by patterning a transparent conductive material into a predetermined electrode pattern (not shown). Thus, in the organic LED display substrate according to the present invention, the transparent conductive material can be in a patterned state. However, the present invention is not limited to this, and includes a state before the transparent conductive material is patterned.

  In the organic LED display device 1, the light emitted from the organic layer 5 is taken out from the anode 4 side. Therefore, a material having a high visible light transmittance is used for the transparent substrate 2. Specifically, in addition to inorganic glass such as alkali glass, alkali-free glass and quartz glass, polyester, polycarbonate, polyether, polysulfone, polyethersulfone, polyvinyl alcohol, and fluorine-containing polymers such as polyvinylidene fluoride and polyvinyl fluoride. Transparent materials such as

The anode 4 is made of a transparent metal having a high work function, an alloy thereof, or another conductive compound. For example, ITO (Indium Tin Oxide), SnO ₂ or ZnO can be used as the anode material.

  On the other hand, a metal having a small work function or an alloy thereof is used for the cathode 6. Specific examples include alkali metals, alkaline earth metals, and metals of Group 3 of the periodic table. Of these, aluminum (Al), magnesium (Mg), or alloys thereof are preferably used because they are inexpensive and have good chemical stability.

  Moreover, FIG. 2 is sectional drawing of the 2nd organic LED display apparatus in this Embodiment.

  As shown in FIG. 2, the organic LED display device 11 includes an organic substrate in which an anode 13, an organic layer 14, an electron injection layer 15, and a cathode 16 that is a transparent electrode are stacked in this order on an opaque substrate 12. The LED element 17 is included. A dielectric film 18 is formed on the cathode 16. Further, the organic LED element 17 is sealed by a transparent sealing member 19 provided on the opaque substrate 12. The sealing member 19 is fixed to the opaque substrate 12 through, for example, an adhesive. In FIG. 2, reference numeral 20 denotes a power source that applies a drive voltage to the organic LED element 17.

  In the organic LED display device 11, the light emitted from the organic layer 14 is extracted to the outside from the cathode 16 side. Therefore, the sealing member 19 includes polyester, polycarbonate, polyether, polysulfone, polyethersulfone, polyvinyl alcohol, polyvinylidene fluoride, polyvinyl fluoride, and the like in addition to inorganic glass such as alkali glass, alkali-free glass, and quartz glass. Transparent materials such as fluorine-containing polymers are used.

Further, a transparent electrode such as ITO, SnO ₂ or ZnO is used for the cathode 16. Further, as the electron injection layer 15, for example, LiF or LiO ₂ can be used.

  In the present embodiment, the following transparent electrode film can be provided on the organic layer 14, and this transparent electrode film can be used as a cathode.

  Specifically, as the transparent electrode film, at least one inorganic compound selected from the group consisting of a metal having a small work function, an oxide thereof and a halide thereof, an electron transporting property, a reduction potential is negative, and the inorganic A two-layer film of a first transparent electrode layer made of a co-evaporated film with an organic compound having a lower reduction potential than the compound and a second transparent electrode layer made of a metal oxide can be used.

  Examples of the inorganic compound include alkali metals such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs), magnesium (Mg), calcium (Ca), strontium ( Alkaline earth metals such as Sr) and barium (Ba), yttrium (Y), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium Rare earth metals such as (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm) and ytterbium (Yb), and oxides and halides of these metals, etc. Is mentioned.

Examples of the organic compound include tris (8-quinolinolato) aluminum complex (Alq ₃ ), bis (8-hydroxy) quinaldine aluminum phenoxide (Alq ′ ₂ OPh), and bis (8-hydroxy) quinaldine. Aluminum-2,5-dimethylphenoxide (BAlq), mono (2,2,6,6-tetramethyl-3,5-heptanedionate) lithium complex (Liq), mono (8-quinolinolato) sodium complex (Naq) ), Mono (2,2,6,6-tetramethyl-3,5-heptanedionate) lithium complex, mono (2,2,6,6-tetramethyl-3,5-heptanedionate) sodium complex and bis (8-quinolinolato) calcium complex (CAQ ₂₎ metal complexes of quinoline derivatives such as, and, Such as carbon clusters or metal complexes thereof having a fullerene structure such as 60 and C70 and the like.

  Further, as the metal oxide constituting the second transparent electrode layer, for example, indium (In), antimony (Sb) or zinc (Zn) oxide, ITO, indium and antimony oxide, and indium and zinc oxide An oxide etc. are mentioned.

In FIG. 2, the anode 13 can be the same as the organic LED display device 1 of FIG. However, the anode material may be any material having a high hole injection capability and a large work function, and not only a transparent material such as ITO, SnO ₂ and ZnO but also an opaque material such as gold (Au) can be used. In the example of FIG. 2, it is assumed that the anode 13 is a transparent electrode.

  On the other hand, an opaque material such as silicon (Si) is used for the substrate 12.

  FIG. 3 is a cross-sectional view of a third organic LED display device in the present embodiment.

  As shown in FIG. 3, the organic LED display device 21 includes a positive electrode 24, an organic layer 25, an electron injection layer 26, and a transparent electrode on a transparent substrate 22 with a first dielectric film 23 interposed therebetween. The organic LED element 28 is laminated with a cathode 27, which is a transparent electrode, in this order. A second dielectric film 29 is formed on the cathode 27. Furthermore, the organic LED element 28 and the second dielectric film 29 are sealed by a transparent sealing member 30 provided on the transparent substrate 22. The sealing member 30 is fixed to the transparent substrate 22 via an adhesive or the like, for example. In FIG. 3, reference numeral 31 denotes a power source that applies a driving voltage to the organic LED element 28.

  In FIG. 3, the substrate for an organic LED display device according to the present invention includes a transparent substrate 22, a first dielectric film 23, and an anode 24. Here, in FIG. 3, the anode 24 is formed by patterning a transparent conductive material into a predetermined electrode pattern (not shown). Thus, in the organic LED display substrate according to the present invention, the transparent conductive material can be in a patterned state. However, the present invention is not limited to this, and includes a state before the transparent conductive material is patterned.

  The transparent substrate 22 and the sealing member 30 include, for example, polyester, polycarbonate, polyether, polysulfone, polyethersulfone, polyvinyl alcohol, polyvinylidene fluoride, and polyvinyl fluoride in addition to inorganic glass such as alkali glass, alkali-free glass, and quartz glass. It can be formed using a transparent material such as a fluorine-containing polymer such as vinyl fluoride.

The anode 24 is made of a transparent metal having a high work function or an alloy thereof or other conductive compound. For example, ITO (Indium Tin Oxide), SnO ₂ or ZnO can be used as the anode material.

For the cathode 27, a transparent electrode such as ITO, SnO ₂ or ZnO is used. As the electron injection layer 26, for example, LiF or LiO ₂ can be used.

  Similar to the organic LED display device 11 of FIG. 2, the following transparent electrode film can be provided on the organic layer 25, and this transparent electrode film can be used as a cathode.

  The transparent electrode film includes at least one inorganic compound selected from the group consisting of metals having a low work function, oxides thereof, and halides thereof, and has an electron transporting property and a reduction potential that is negative and is reduced more than the inorganic compounds. A two-layer film of a first transparent electrode layer made of a co-evaporated film with a low potential organic compound and a second transparent electrode layer made of a metal oxide can be used.

  The organic LED element (1, 11, 21) described above can be a three-layer element in which the organic layers (5, 14, 25) are each composed of a hole transport layer, a light emitting layer, and an electron transport layer. .

  Moreover, these organic LED elements can also be made into the 2 layer type element in which a light emitting layer has hole transport property or electron transport property.

  Furthermore, in order to lower the hole injection barrier from the anode, there may be a structure in which one hole injection layer having a small difference in ionization potential from the anode is provided between the hole transport layer and the anode. it can.

  Examples of the hole transport layer include N, N′-bis (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPD), N, N′— Diphenyl-N, N′-bis [N-phenyl-N- (2-naphthyl) -4′-aminobiphenyl-4-yl] -1,1′-biphenyl-4,4′-diamine (NPTE), 1 , 1-bis [(di-4-tolylamino) phenyl] cyclohexane (HTM2) and N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-diphenyl-4,4 ′ -Diamine (TPD) etc. are mentioned.

  Examples of the electron transport layer include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND) and 2- (4-t-butylphenyl) -5- (4-biphenyl). -1,3,4-oxadiazole (PBD) and the like.

The light emitting layer is made of a material that provides a field where injected electrons and holes can be recombined and has high light emission efficiency. Specifically, tris (8-quinolinolato) aluminum complex (Alq ₃ ), bis (8-hydroxy) quinaldine aluminum phenoxide (Alq ′ ₂ OPh), bis (8-hydroxy) quinaldine aluminum-2,5- Dimethylphenoxide (BAlq), mono (2,2,6,6-tetramethyl-3,5-heptanedionate) lithium complex (Liq), mono (8-quinolinolato) sodium complex (Naq), mono (2, 2,6,6-tetramethyl-3,5-heptanedionate) lithium complex, mono (2,2,6,6-tetramethyl-3,5-heptanedionate) sodium complex and bis (8-quinolinolate) metal complexes of quinoline derivatives such as calcium complex (CAQ _2), tetraphenyl butadiene, Feniruki Kudrin (QD), anthracene, and a fluorescent substance such as perylene and coronene.

  The fluorescent material is preferably used as a dopant in combination with a host material capable of emitting light by itself. As a result, the emission wavelength characteristic of the host material can be changed, light emission shifted to a long wavelength can be achieved, and the light emission efficiency and stability of the device can be improved.

  As the host substance, a quinolinolato complex is preferable, and an aluminum complex having 8-quinolinol and a derivative thereof as a ligand is particularly preferable.

  Each of the organic LED display devices (1, 11, 21) described above has a dielectric film (3, 18, 23, 29). That is, this embodiment is characterized in that a dielectric film is provided in contact with the transparent electrode. Here, the dielectric film is transparent and has the same refractive index as the organic layer and the transparent electrode.

  Hereinafter, the dielectric films (3, 18, 23, 29) in the first organic LED display device 1, the second organic LED display device 11, and the third organic LED display device 21 will be specifically described.

In the first organic LED display device 1 shown in FIG. 1, emitted light is extracted from the anode 24 side. In this case, the refractive index of the organic layer 5 is n ₁ , the refractive index of the anode 4 is n ₂ , and the refractive index of the dielectric film 3 is n ₂ in the visible light wavelength range (450 nm to 650 nm). ₃
| N ₃ −n ₂ | ≦ 0.25 (1)
And | n ₁ −n ₂ | ≦ 0.20 (2)
It is necessary to establish the relationship.

Especially in the above wavelength range,
| N ₃ −n ₂ | ≦ 0.20 and | n ₁ −n ₂ | ≦ 0.20
It is preferable that the relationship is established.

In the organic LED display device 11 of FIG. 2, emitted light is extracted from the cathode 16 side. In this case, in the wavelength region of 450 nm to 650 nm, the refractive index of the organic layer 14 is n ₁ ′, the refractive index of the cathode 16 is n ₂ ′, the refractive index of the dielectric film 18 is n ₃ ′, and the refractive index of the anode 13 is. n ₄ ′,
| N ₃ ′ −n ₂ ′ | ≦ 0.25,
| N ₁ ′ −n ₂ ′ | ≦ 0.20 and | n ₁ ′ −n ₄ ′ | ≦ 0.20
It is necessary to establish the relationship.

Especially in the above wavelength range,
| N ₃ ′ −n ₂ ′ | ≦ 0.20,
| N ₁ ′ −n ₂ ′ | ≦ 0.20 and | n ₁ ′ −n ₄ ′ | ≦ 0.20
It is preferable that the relationship is established.

However, in the organic LED display device 11 of FIG. 2, when the anode 13 is an opaque electrode, in the wavelength region of 450 nm to 650 nm,
| N ₃ '-n ₂ ' | ≦ 0.25 and | n ₁ '-n ₂ ' | ≦ 0.20
It is sufficient if the relationship is established.

In particular, when the anode 13 is an opaque electrode,
| N ₃ ′ −n ₂ ′ | ≦ 0.20 and | n ₁ ′ −n ₂ ′ | ≦ 0.20
It is preferable that the relationship is established.

Further, in the organic LED display device 21 of FIG. 3, emitted light is extracted from both sides of the anode 24 and the cathode 27. In this case, in the wavelength region of 450 nm to 650 nm, the refractive index of the organic layer 25 is n ₁ ″, the refractive index of the anode 24 is n ₂ ″, the refractive index of the first dielectric film 23 is n ₃ ″, and When the refractive index is n ₄ ″ and the refractive index of the second dielectric film 29 is n ₅ ″,
| N ₃ ″ −n ₂ ″ | ≦ 0.25,
| N ₅ ″ −n ₄ ″ | ≦ 0.25,
| N ₁ ′ −n ₂ ′ | ≦ 0.20 and | n ₁ ′ −n ₄ ′ | ≦ 0.20
It is necessary to establish the relationship.

Especially in the above wavelength range,
| N ₃ ″ −n ₂ ″ | ≦ 0.20,
| N ₅ ″ −n ₄ ″ | ≦ 0.20,
| N ₁ ″ -n ₂ ″ | ≦ 0.20 and | n ₁ ″ -n ₄ ″ | ≦ 0.20
It is preferable that the relationship is established.

  Note that the dielectric film in the present invention does not continuously change the refractive index in the film thickness direction, but has a substantially uniform refractive index in the film.

  FIG. 6 shows the change in color difference with respect to the refractive index of the dielectric film in the wavelength region of 450 nm to 650 nm for the organic LED display device having the structure of FIG.

  6 shows an organic LED display device in which a dielectric film, ITO, an organic layer, and an aluminum film are laminated in this order on a glass substrate. Here, it is assumed that the relationship of formula (2) is established between the ITO and the organic layer. The organic layer includes a hole transport layer, a blue light-emitting layer, a yellow light-emitting layer, and an electron transport layer, and light emitted from the organic layer is white light. This is because the chromaticity change in white light is generally recognized most sensitively by the observer.

  Further, in FIG. 6, the refractive index of the dielectric film is expressed as a ratio to the refractive index of ITO. However, “none” on the horizontal axis corresponds to a conventional example without a dielectric film.

  As can be seen from FIG. 6, the color difference can be made smaller than before by providing a dielectric film having a refractive index comparable to that of ITO between the glass substrate and ITO.

  Generally, when the color difference (Δx and Δy) changes by ± 0.03 or more, a change in chromaticity is easily recognized by an observer. Therefore, in the example of FIG. 6, the refractive index of the dielectric film with respect to the refractive index of ITO is preferably 0.9 times to 1.2 times, and more preferably 1.0 times to 1.2 times. .

  FIG. 7 shows the change in color difference with respect to the film thickness of the dielectric film in the wavelength region of 450 nm to 650 nm for the organic LED display device having the same structure as that in FIG. “None” on the horizontal axis corresponds to a conventional example without a dielectric film.

  As can be seen from FIG. 7, the color difference tends to decrease as the thickness of the dielectric film increases. In the figure, when the range where the color difference (Δx and Δy) is ± 0.03 or less is seen, the thickness of the dielectric film is preferably 0.5 μm or more. On the other hand, when the film thickness of the dielectric film becomes too large, problems such as difficulty in film formation occur. Therefore, the film thickness is more preferably 0.5 μm or more and 2.0 μm or less. Further, it is more preferable that the film thickness is 1.0 μm or more and 2.0 μm or less because the color difference can be further reduced.

As the dielectric film of the present invention, an inorganic compound composed of at least two elements selected from the group consisting of silicon (Si), oxygen (O), nitrogen (N) and aluminum (Al) is preferably used. In particular, silicon oxide (SiO _x ), silicon nitride (Si _x N _y ), silicon oxynitride (SiO _x N _y ), aluminum nitride (AlN _x ), aluminum oxynitride (AlO _x N _y ) or sialon (SiAlO _x N _y ) and the like are preferably used. These inorganic compounds can be formed into a film having a desired refractive index by appropriately adjusting the ratio of each component. These films can be formed by, for example, a plasma CVD (Chemical Vapor Deposition) method or a sputtering method.

  The dielectric film may have a structure in which fine particles of metal oxide are dispersed in a binder. In this case, a dielectric film having a desired refractive index can be obtained by appropriately selecting the refractive index of the metal oxide.

For example, examples of the metal oxide include titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), zinc oxide (ZnO ₂ ), cerium oxide (CeO ₂ ), and the like.

  Examples of the binder include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, carboxypolycaprolactone acrylate, acrylic acid, methacrylic acid, and acrylamide. Monofunctional (meth) acrylates and diacrylates such as pentaerythritol triacrylate, ethylene glycol diacrylate and pentaerythritol diacrylate monostearate, tri (meth) acrylates such as trimethylolpropane triacrylate and pentaerythritol triacrylate, pentaerythritol Tetraacrylate derivatives and dipentaerythritol pentaacrylate It is possible to polymerize monomers such as polyfunctional (meth) acrylate of formation.

  Besides the above polymer of monomers, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyamide resin, polyimide resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine -A binder can also be formed using urea co-condensation resin, silicon resin, polysiloxane resin, and the like.

  However, when an organic compound is used as the dielectric film, it is necessary to prevent moisture contained in the organic film from diffusing into the organic LED element to form a non-light emitting region. It is also important to select one that is resistant to the photolithography process performed in the manufacturing process of the organic LED display device.

  Next, light interference when a dielectric film is provided will be described.

  When a voltage is applied to the organic LED element 1 in FIG. 1, holes are injected from the anode 4 into the hole transport layer in the organic layer 5. This hole then moves to the light emitting layer. On the other hand, electrons are injected from the cathode 6 into the electron transport layer in the organic layer 5. Then, electrons diffuse in the light emitting layer. Thereafter, when holes and electrons are recombined in the light emitting layer, the light emitting material and fluorescent molecules in the light emitting layer are excited by the released energy. The energy released when the excited molecule returns to the ground state appears in the form of light emission.

  In FIG. 1, the light emitted from the light emitting region includes the light 41 directed forward (downward in the drawing) of the organic LED element 7, and once directed toward the back surface (upward in the drawing), and then the cathode 6. There is also light 42 which is reflected forward and then travels forward.

  In the present embodiment, the relationship of the above formulas (1) and (2) is established among the materials constituting the dielectric layer 3, the anode 4 and the organic layer 5. That is, the refractive index difference between them is small. On the other hand, the refractive index difference between the transparent substrate 2 and the dielectric film 3 is larger than these, and a large refractive index step is produced at the interface. For example, the refractive index of inorganic glass is about 1.55, and the polymer is about the same (for example, the refractive index of polycarbonate is 1.58). Therefore, a part of the light 42 reflected by the cathode 6 and traveling forward (the light 43 in FIG. 1) is reflected at the interface between the dielectric film 3 and the transparent substrate 2. Then, it goes to the back direction, is reflected by the cathode 6 again, and goes to the front. Further, a part of the light 42 (light 44 in FIG. 1) is also reflected by the interface between the dielectric film 3 and the transparent substrate 2 and directed toward the back surface, and then again reflected by the cathode 6 and directed forward.

  There are mainly four types of light (lights 41, 42, 43, and 44) that affect the angle dependency of chromaticity due to interference. In other words, the intensity of light that is reflected more than this may be considered to have little influence on the angle dependency because the intensity becomes weak.

  In the organic LED display device 1 of FIG. 1, since the dielectric film 3 is provided between the transparent substrate 2 and the anode 4, the distance from the light emission position toward the front to the reflecting surface is the conventional distance shown in FIG. Longer than the configuration of That is, since the optical path lengths of the light 43 and the light 44 are longer than the conventional one, the modulation spectrum obtained by the interference of the light 41, 42, 43, 44 has a shorter period and a smaller amplitude than the conventional modulation spectrum. Become.

  In general, the intensity of light depends on the wavelength λ and is visually recognized by an observer. That is, light of a certain wavelength is recognized strongly, while light of another wavelength is recognized weakly. For example, in a conventional organic LED display device, when an observer looks at the display by gradually increasing the angle from the normal direction of the substrate, the white light gradually becomes yellow as a result of increased absorption in the wavelength region of 550 nm to 600 nm. The taste becomes visible.

  Here, the emission spectrum when the observer actually looks at the display is considered to be equal to the emission spectrum of the composite wave obtained by superimposing the four types of light (41, 42, 43, 44) in FIG. As described above, according to the present invention, by providing the dielectric film, the modulation spectrum obtained by the interference of the above four types of light can be made short and have a small amplitude. As a result, it is possible to obtain an emission spectrum in which the tendency for the intensity of light of a specific wavelength to increase or decrease depending on the viewing angle can be obtained, so that it is possible to suppress the chromaticity from changing according to the viewing angle. Become.

  The same applies to the organic LED display device 11 of FIG. 2 and the organic LED display device 21 of FIG.

  In the organic LED display device 11 of FIG. 2, the light emitted from the light emitting region is once in the back direction (downward direction of the drawing) in addition to the light 51 traveling in front of the organic LED element 17 (upward direction of the drawing). There is also light 52 that travels forward after being reflected at the interface between the anode 13 and the opaque substrate 12.

  By the way, between the dielectric film 18 and the sealing member 19 is a vacuum (refractive index 1) or an inert gas atmosphere. Accordingly, a part of the light 52 reflected by the opaque substrate 12 and directed forward (the light 53 in FIG. 2) is reflected by the surface of the dielectric film 18. Then, it goes to the back direction, is reflected by the opaque substrate 12 again, and goes to the front.

  A part of the light 52 (light 54 in FIG. 2) is also reflected by the surface of the dielectric film 18 toward the back surface and then reflected by the opaque substrate 12 and directed forward. However, in this case, since the intensity of the light 54 reflected twice by the opaque substrate 12 is very small, it is considered that the influence is small compared to other light (51, 52, 53).

  From the above, the light that affects the angular dependency of chromaticity by interference is mainly the above three types (lights 51, 52, and 53).

  In the organic LED display device 11 of FIG. 2, since the dielectric film 18 is provided on the cathode 16, the distance from the light emission position toward the reflection surface to the reflection surface is compared with the case where the dielectric film 18 is not provided. Then, it becomes longer by the film thickness of the dielectric film 18. Therefore, the interference due to the light 53 has a short period and a small amplitude compared to the conventional case, so that the change in chromaticity according to the viewing angle can be suppressed as in the example of FIG.

In FIG. 2, when the anode 13 is an opaque electrode, the light emitted from the light emitting region is reflected at the interface between the anode 13 and the organic layer 14 and travels forward. Therefore, in this case, the refractive index _n 1 of the organic layer 14 ', the refractive index _{n 2} of the cathode 16' between the refractive index _{n 3} and of the dielectric layer 18 ', in the wavelength region of 450 nm to 650 nm,
| N ₃ '-n ₂ ' | ≦ 0.25 and | n ₁ '-n ₂ ' | ≦ 0.20
It is sufficient if the relationship is established.

  In the example of FIG. 2, an organic film (for example, a film made of a photosensitive epoxy resin) for improving visibility may be provided between the dielectric film 18 and the sealing member 19. . In this case, since a refractive index step is generated between the dielectric film 18 and the organic film, the light 53 ′ and 54 ′ is reflected at the interface between the dielectric film 18 and the organic film 55 as shown in FIG. . That is, the reflection is the same as in FIG.

  In the organic LED display device 21 of FIG. 3, the light emitted from the light emitting region includes light 61 directed toward the anode 24 (downward in the figure) of the organic LED element 21 and the cathode 27 side (upward in the figure). ) To the light 62. A part of the light 61 is reflected at the interface between the transparent substrate 22 and the first dielectric film 23 and travels toward the cathode 27 (light 63). A part of the light 62 is reflected by the surface of the second dielectric film 29 and travels toward the anode 24 (light 64). Furthermore, a part of the light 63 is reflected by the surface of the second dielectric film 29 and travels toward the anode 24 (light 65). Part of the light 64 is further reflected at the interface between the transparent substrate 22 and the first dielectric film 23 and travels toward the cathode 27 (light 66).

  There are mainly six types of light (lights 61, 62, 63, 64, 65, 66) that affect the angle dependency of chromaticity due to interference.

  In the organic LED display device 21 of FIG. 3, since the first dielectric film 23 is provided between the transparent substrate 22 and the anode 24, the distance from the light emission position toward the anode 24 side to the reflection surface is Compared to the case where the first dielectric film 23 is not provided, the length is increased by the thickness of the first dielectric film 23. Further, since the organic LED display device 21 is provided with the second dielectric film 29 on the cathode 27, the distance from the light emitting position toward the cathode 27 to the reflecting surface is the second dielectric film. Compared to the case where 29 is not provided, the length is increased by the thickness of the second dielectric film 29. Therefore, since the interference due to the light 63, 64, 65, 66 has a short period and a small amplitude compared to the conventional case, it is possible to suppress the chromaticity from changing according to the viewing angle as in the example of FIG. It becomes possible to do.

  In the example of FIG. 3, an organic film (for example, a film made of a photosensitive epoxy resin) for improving visibility may be provided between the dielectric film 29 and the sealing member 30. In this case, since a refractive index step is generated between the dielectric film 29 and the organic film, the light 64 ′, 65 ′, and 66 ′ are interfaced between the dielectric film 29 and the organic film 67 as shown in FIG. Reflect on. That is, the reflection is the same as in FIG.

  In FIGS. 2 and 3, the thickness of the electron injection layer (15, 26) provided between the organic layer (14, 25) and the cathode (16, 27) is as thin as several tens. For this reason, it is considered that the influence of the electron injection layer (15, 26) on the color difference is almost negligible, so that the refractive index of this layer need not be a problem.

  As described above, by providing at least one of the anode and the cathode as a transparent electrode and providing a dielectric layer in contact with the transparent electrode on the side opposite to the organic layer, an organic LED display excellent in viewing angle dependency of chromaticity A device can be obtained.

  That is, as shown in the present embodiment, by providing a dielectric film having a predetermined refractive index and film thickness, the refractive index and film of each film constituting an organic LED element such as an anode, an organic layer, and a cathode. The need to strictly control the thickness can be eliminated. Further, the dielectric film only needs to have a substantially uniform refractive index in the film, and it is not necessary to take measures such as the refractive index continuously changing in the film thickness direction. Furthermore, in this embodiment, since the change in chromaticity depending on the viewing angle is evaluated with white light, it is obvious that the same effect can be obtained for other colors. Therefore, according to the present invention, it is possible to easily provide a display having a small change in chromaticity depending on the viewing angle for each color.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, by providing unevenness on the surface of the dielectric film, it is possible to further suppress chromaticity changes due to interference.

  Examples of the present invention will be described below.

Example The configuration of an organic LED display device was as shown in FIG. That is, the organic LED display device 71 has a structure in which a dielectric film 73, ITO (film thickness 150 nm) 74, an organic layer 75, and an aluminum film (film thickness 100 nm) 76 are laminated in this order on a glass substrate 72. is doing. The organic layer 75 includes, in order from the ITO 74 side, a hole transport layer (film thickness 50 nm) 77, a blue light-emitting layer (film thickness 30 nm) 78, a yellow light-emitting layer (film thickness 30 nm) 79, and an electron transport layer (film thickness). 20 nm) 80.

As the hole transport layer 77, HT320 made by Idemitsu Kosan Co., Ltd. was used. Moreover, as the blue light emitting layer 78, what doped BD120 (made by Idemitsu Kosan Co., Ltd.) which is a blue dopant in BH120 (made by Idemitsu Kosan Co., Ltd.) as a light emitting layer host was used. Further, as the yellow light emitting layer 79, BH120 as a light emitting layer host doped with YD103 (made by Idemitsu Kosan Co., Ltd.) which is a yellow dopant was used. Furthermore, as the electron transport layer 80, tris (8-quinolinolato) aluminum complex (Alq ₃ ) was used.

FIG. 9 is a diagram comparing the refractive indexes of the constituent materials. The refractive index was measured by spectroscopic ellipsometry (WVASE32 manufactured by JA Woollam). As can be seen, in the wavelength region of 450 nm to 650 nm, and the refractive index _{n ITO} of ITO, the hole refractive index of the transport layer n _alpha, the refractive index of the blue light-emitting layer n _beta, and _gamma n the refractive index of the yellow light emitting layer Between the refractive index n _δ of the electron transport layer, the relationship of formula (2), that is,
| N _ITO −n _α | ≦ 0.20
| N _ITO −n _β | ≦ 0.20
| N _ITO −n _γ | ≦ 0.20
| N _ITO −n _δ | ≦ 0.20
Is established.

  In FIG. 8, it is assumed that the light emission position is the interface between the blue light emitting layer 78 and the yellow light emitting layer 79 for both blue and yellow. The refractive index of the dielectric film 73 is assumed to be the same as that of the ITO 74.

  10 to 13, the thickness of the dielectric film is set to 0.3 μm, 0.5 μm, 1.0 μm, and 2.0 μm, respectively, and the change of the modulation spectrum with respect to the viewing angle is obtained by simulation using self-made software. The results are shown. The viewing angle was changed to 0 degrees, 20 degrees, 40 degrees and 60 degrees with respect to the normal direction of the panel.

  Specifically, the modulation spectrum was obtained as follows. However, in FIG. 8, only the interference between the light beams 81, 82, 83, and 84 was considered, with the reflection at the aluminum film being limited to twice and ignoring the reflection three or more times. Further, reflection on the back surface of the glass substrate 72 is not considered.

FIG. 32 shows the optical path of the light 81 in FIG. 8 more specifically. However, in the organic layer 75, the hole transport layer 77, the blue light emitting layer 78, the yellow light emitting layer 79, and the electron transport layer 80 are omitted (the same applies to FIGS. 33 to 35 described below). As shown in FIG. 32, as there is a light-emitting position from the aluminum film 76 to the distance d _0, the emission direction from the light-emitting position of the light 81, the angle between the direction perpendicular to the organic layer 75 and theta ¹ _1. The emission angles of the light 81 from the organic layer 75, ITO 74, dielectric film 73, and glass substrate 72 are θ ¹ ₂ , θ ¹ ₃ , θ ¹ _4, and θ ¹ ₅ , respectively.

FIG. 33 shows the optical path of the light 82 in FIG. 8 more specifically. Similarly to FIG. 32, it is assumed that there is a light emitting position at a distance d ₀ from the aluminum film 76. Then, the emission direction from the light-emitting position of the light 82, the angle between the direction perpendicular to the organic layer 75 and theta ² _0. The reflection angle of the light 82 from the aluminum film 76 is θ ² _1, and the emission angles of the light 82 from the organic layer 75, ITO 74, dielectric film 73 and glass substrate 72 are θ ² ₂ , θ ² ₃ , and and theta ² ₄ and theta ² _5.

FIG. 34 shows the optical path of the light 83 in FIG. 8 more specifically. Similarly to FIG. 32, it is assumed that there is a light emitting position at a distance d ₀ from the aluminum film 76. The angle formed between the emission direction of the light 83 from the light emission position and the direction perpendicular to the organic layer 75 is defined as θ ³ ₁ . The emission angles of the light 82 from the organic layer 75, the ITO 74, the dielectric film 73, and the glass substrate 72 are θ ³ ₂ , θ ³ ₃ , θ ³ _4, and θ ³ ₅ , respectively.

FIG. 35 shows the optical path of the light 84 in FIG. 8 more specifically. Similarly to FIG. 32, it is assumed that there is a light emitting position at a distance d ₀ from the aluminum film 76. Then, the emission direction from the light-emitting position of the light 84, the angle between the direction perpendicular to the organic layer 75 and theta ⁴ _0. The reflection angle of the light 84 from the aluminum film 76 is θ ⁴ _1, and the emission angles of the light 84 from the organic layer 75, ITO 74, dielectric film 73, and glass substrate 72 are respectively θ ⁴ ₂ , θ ⁴ ₃ , Let them be θ ⁴ ₄ and θ ⁴ ₅ .

32 to 35, the refractive index of the organic layer 75 is n ₁ , the film thickness is d ₁ , the refractive index of ITO 74 is n ₂ , the film thickness is d ₂ , and the refractive index of the dielectric film 73 is n ₃ , The film thickness is d ₃ , the refractive index of the glass substrate 72 is n ₄ , and the thickness is d ₄ .

In lights 81 and 82,
sin θ ⁱ ₁ / sin θ ⁱ ₅ = 1 / n ₁ (i = 1 or 3)
The relationship is established.

Moreover, in the lights 82 and 83,
Since sin θ ⁱ ₁ = sin θ ^j ₁ (i = 1 or 3, j = 2 or 4),
θ ^j ₀ = πθ ⁱ ₁
The relationship is established.

Furthermore, Snell's law is established for light passing through each of the organic layer 75, the ITO 74, the dielectric film 73, and the glass substrate 72.
sin θ ⁱ _k / sin θ ⁱ _{k + 1} = n _{k + 1} / n _k
(I = 1, 2, 3 or 4, k = 1, 2, 3 or 4)
It becomes.

Next, spectrum, assuming that only the light 81 is emitted to the outside in FIG. 8 (hereinafter, referred to as the original emission spectrum.) The ^I (λ) ^e iωt (where, ω = 2πc / λ, c : Fast) Assuming each phase of the four types of light (81, 82, 83, 84).

With respect to the light 81, when the optical path length in the organic layer 75 is L ¹ ₁ , the optical path length in the ITO 74 is L ¹ ₂ , the optical path length in the dielectric film 73 is L ¹ ₃ , and the optical path length in the glass substrate 72 is L ¹ _4. Is represented by the following equations.

L ¹ ₁ = (d ₁ d ₀ ) / cos θ ¹ ₁
L ¹ ₂ = d ₂ / cos θ ¹ ₂
L ¹ ₃ = d ₃ / cos θ ¹ ₃
L ¹ ₄ = d ₄ / cos θ ¹ ₄

Therefore, the emission spectrum of the light 81 at the wavelength λ is
I ¹ _out (λ, t) = I (λ) exp [i {ωt · 2πΣ (L ¹ _k / λ)}]
(K = 1, 2, 3 or 4, t: time)
It is represented by

For the light 82, the optical path length in the organic layer 75 is L ² ₁ , the optical path length in the ITO 74 is L ² ₂ , the optical path length in the dielectric film 73 is L ² ₃ , and the optical path length in the glass substrate 72 is L ² _4. These are represented by the following equations, respectively.

L ² ₁ = 2d ₀ / cos (πθ ² ₁ ) + (d ₁ d ₀ ) / cos θ ² ₁
L ² ₂ = d ₂ / cos θ ² ₂
L ² ₃ = d ₃ / cos θ ² ₃
L ² ₄ = d ₄ / cos θ ² ₄

Therefore, the emission spectrum of the light 82 is
I ² _out (λ, t) = I (λ) exp [i {ωt · 2πΣ (L ² _k / λ)}]
(K = 1, 2, 3 or 4, t: time)
It is represented by

For the light 83, the optical path length in the organic layer 75 is L ³ ₁ , the optical path length in the ITO 74 is L ³ ₂ , the optical path length in the dielectric film 73 is L ³ ₃ , and the optical path length in the glass substrate 72 is L ³ _4. These are represented by the following equations, respectively.

L ³ ₁ = 2d ₀ / cos (πθ ³ ₁ ) +3 (d ₁ d ₀ ) / cos θ ³ ₁
L ³ ₂ = 3d ₂ / cos θ ³ ₂
L ³ ₃ = 3d ₃ / cos θ ³ ₃
L ³ ₄ = 3d ₄ / cos θ ³ ₄

Therefore, the emission spectrum of the light 83 is
I ³ _out (λ, t) = I (λ) exp [i {ωt · 2πΣ (L ³ _k / λ)}]
(K = 1, 2, 3 or 4, t: time)
It is represented by

Further, regarding the light 84, when the optical path length in the organic layer 75 is L ⁴ ₁ , the optical path length in the ITO 74 is L ⁴ ₂ , the optical path length in the dielectric film 73 is L ⁴ ₃ , and the optical path length in the glass substrate 72 is L ⁴ _4. These are represented by the following equations, respectively.

L ⁴ ₁ = 4d ₀ / cos (πθ ³ ₁ ) +3 (d ₁ d ₀ ) / cos θ ³ ₁
L ⁴ ₂ = 3d ₂ / cos θ ³ ₂
L ⁴ ₃ = 3d ₃ / cos θ ³ ₃
L ⁴ ₄ = 3d ₄ / cos θ ³ ₄

Therefore, the emission spectrum of the light 84 is
I ⁴ _out (λ, t) = I (λ) exp [i {ωt · 2πΣ (L ⁴ _k / λ)}]
(K = 1, 2, 3 or 4, t: time)
It is represented by

From the above, the emission spectrum actually observed due to interference of light (81, 82, 83, 84) is
I _total = (λ, t, θ) = ΣI ^k _out (k = 1, 2, 3, or 4)
It becomes.

Also, d ₀ and the original emission spectrum are determined by obtaining emission spectra for four types of light (81, 82, 83, 84) by changing the above-mentioned angles. That is, d ₀ and the original emission spectrum satisfy the above-described calculation formulas at any angle. The modulation spectrum is obtained by dividing the emission spectrum by the original emission spectrum.

  14 to 17 show changes in the emission spectrum with respect to the viewing angle when the thickness of the dielectric film is 0.3 μm, 0.5 μm, 1.0 μm, and 2.0 μm. The viewing angle was changed to 0 degrees, 20 degrees, 40 degrees, and 60 degrees with respect to the normal direction of the panel as in FIGS.

  18 to 21 show the viewing angle dependence of chromaticity obtained from the emission spectra of FIGS. 14 to 17.

  22 to 26 show changes in the modulation spectrum with respect to the viewing angle when the refractive index of the dielectric film is changed. The viewing angle was changed to 0 degree, 20 degrees, 40 degrees and 60 degrees with respect to the normal direction of the panel. The thickness of the dielectric film was 1.0 μm, and the modulation spectrum was obtained in the same manner as in FIGS. The refractive index of the dielectric film is changed with respect to the refractive index of ITO, and FIG. 22 corresponds to the case where the dielectric film and ITO have the same refractive index.

  27 to 31 show changes in the emission spectrum with respect to the viewing angle when the refractive index of the dielectric film is changed. The viewing angle was changed to 0 degree, 20 degrees, 40 degrees and 60 degrees with respect to the normal direction of the panel. The film thickness of the dielectric film was 1.0 μm, and the emission spectrum was obtained in the same manner as in FIGS. Further, the refractive index of the dielectric film is changed with respect to the refractive index of ITO, and FIG. 27 corresponds to the case where the dielectric film and ITO have the same refractive index.

Comparative Example FIG. 36 shows the change in the modulation spectrum with respect to the viewing angle when the dielectric film 72 is not provided in FIG. The viewing angle was changed to 0 degree, 20 degrees, 40 degrees and 60 degrees with respect to the normal direction of the panel. This corresponds to the modulation spectrum in the conventional organic LED display device.

  FIG. 37 shows the change in the emission spectrum with respect to the viewing angle for the same structure as in FIG. The modulation spectrum and emission spectrum were determined in the same manner as in the above example. The viewing angle is changed to 0 degrees, 20 degrees, 40 degrees and 60 degrees with respect to the normal direction of the panel, and it can be seen that the yellow color gradually increases as the viewing angle increases.

  Further, FIG. 38 shows the viewing angle dependence of chromaticity obtained from the emission spectrum of FIG.

Example of schematic cross-sectional view of first organic LED display device of embodiment Example of schematic sectional view of second organic LED display device of embodiment Example of schematic cross-sectional view of third organic LED display device according to embodiment Another example of a schematic cross-sectional view of the second organic LED display device of the embodiment Another example of a schematic cross-sectional view of the third organic LED display device of the embodiment The figure showing the color difference change with respect to the refractive index of the dielectric film in the wavelength range of 450 nm-650 nm about the organic LED display device of FIG. 1 of embodiment. The figure showing the color difference change with respect to the film thickness of the dielectric film in the wavelength range of 450 nm-650 nm about the organic LED display apparatus of FIG. 6 of embodiment. Cross-sectional schematic diagram of organic LED display device in Examples The figure which compared the refractive index of each structural material about the organic LED display apparatus of FIG. 8 of an Example. The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (film thickness of an electric film is 0.3 micrometer) The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (film thickness of an electric film is 0.5 micrometer) The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (film thickness of an electric film is 1.0 micrometer). The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (film thickness of an electric film is 2.0 micrometers) The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the film thickness of a dielectric film is 0.3 micrometer). The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the film thickness of a dielectric film is 0.5 micrometer). The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the film thickness of a dielectric film is 1.0 micrometer). The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the film thickness of a dielectric film is 2.0 micrometers). The figure which shows the viewing angle dependence of chromaticity in an Example (film thickness of a dielectric film is 0.3 micrometer) The figure which shows the viewing angle dependence of chromaticity in an Example (film thickness of a dielectric film is 0.5 micrometer) The figure which shows the viewing angle dependence of chromaticity in an Example (film thickness of a dielectric film is 1.0 micrometer) The figure which shows the viewing angle dependence of chromaticity in an Example (film thickness of a dielectric film is 2.0 micrometers) The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is the same as ITO) The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is 0.8 times of ITO) The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is 0.9 time of ITO). The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is 1.2 times of ITO). The figure which shows the change of the modulation spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is 1.3 times of ITO). The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is the same as ITO) The figure which shows the change of the emission spectrum with respect to a viewing angle in the Example (the refractive index of the dielectric film is 0.8 times that of ITO). The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is 0.9 time of ITO). The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is 1.2 times of ITO). The figure which shows the change of the emission spectrum with respect to a viewing angle in an Example (the refractive index of a dielectric film is 1.3 times of ITO). The figure which shows the optical path of the light radiate | emitted from the organic LED display apparatus of FIG. 8 in an Example. The figure which shows the optical path of the light radiate | emitted from the organic LED display apparatus of FIG. 8 in an Example. The figure which shows the optical path of the light radiate | emitted from the organic LED display apparatus of FIG. 8 in an Example. The figure which shows the optical path of the light radiate | emitted from the organic LED display apparatus of FIG. 8 in an Example. The figure which shows the change of the modulation spectrum with respect to a viewing angle in a comparative example The figure which shows the change of the emission spectrum with respect to a viewing angle in a comparative example The figure which shows the viewing angle dependence of chromaticity in a comparative example Cross-sectional schematic diagram of a conventional organic LED display device

Explanation of symbols

1,11,21,71,91 Organic LED display device 2,22 Transparent substrate 3,18,73 Dielectric film 4,13,24 Anode 5,14,25,75 Organic layer 6,16,27 Cathode 7,17 , 28 Organic LED element 8, 19, 30 Sealing member 9, 20, 31 Power supply 12 Opaque substrate 15, 26 Electron injection layer 23 First dielectric film 29 Second dielectric film 55, 67, 94 Organic film 72 , 92 Glass substrate 74,93 ITO
76,95 Aluminum film 77 Hole transport layer 78 Blue light-emitting layer 79 Yellow light-emitting layer 80 Electron transport layer

Claims (21)

In an organic LED element comprising an organic layer sandwiched between an anode and a cathode,
At least one of the anode and the cathode is a transparent electrode,
Having a dielectric layer in contact with the transparent electrode on the opposite side of the organic layer;
The dielectric layer has a thickness of 0.5 μm or more,
In the wavelength region of 450 nm to 650 nm, at least | n ₃ −n ₂ | ≦ 0... Between the refractive index n _{1 of} the organic layer, the refractive index n _{2 of the} transparent electrode, and the refractive index n ₃ of the dielectric film. 25
And | n ₁ −n ₂ | ≦ 0.20
The organic LED element characterized by the above relationship being established.   The organic LED element according to claim 1, wherein the dielectric layer has a thickness of 0.5 μm to 2.0 μm.   The organic LED element according to claim 2, wherein the dielectric layer has a thickness of 1.0 μm to 2.0 μm. In the wavelength region of 450 nm to 650 nm, the refractive index n _{1 of} the organic layer, the refractive index n _{2 of the} transparent electrode, and the refractive index n ₃ of the dielectric film,
| N ₃ −n ₂ | ≦ 0.20
And | n ₁ −n ₂ | ≦ 0.20
The organic LED element according to any one of claims 1 to 3, wherein the relationship is established.   5. The organic LED element according to claim 1, wherein the dielectric film is composed of at least two elements selected from the group consisting of silicon, oxygen, nitrogen, and aluminum. The dielectric film is any one film selected from the group consisting of a SiO _x film, a Si _x N _y film, an AlN _x film, a SiO _x N _y film, an AlO _x N _y film, and a SiAlO _x N _y film. The organic LED element of Claim 5.   The organic LED element according to claim 1, wherein the organic layer emits white light. A transparent substrate;
A dielectric film provided on the transparent substrate;
An organic LED element provided on the dielectric film and having an organic layer sandwiched between an anode made of a transparent conductive material and a cathode made of a metal having a small work function or an alloy of the metal;
A sealing member that is provided on the transparent substrate and seals the organic LED element;
The dielectric layer has a thickness of 0.5 μm or more,
In the wavelength region of 450 nm to 650 nm, the refractive index n _{1 of} the organic layer, the refractive index n _{2 of the} anode, and the refractive index n ₃ of the dielectric film,
| N ₃ −n ₂ | ≦ 0.25
And | n ₁ −n ₂ | ≦ 0.20
An organic LED display device characterized in that the above relationship is established. An opaque substrate;
An organic LED element provided on the opaque substrate and having an organic layer sandwiched between an anode and a cathode made of a transparent conductive material;
A dielectric film provided on the cathode;
A transparent sealing member that is provided on the opaque substrate and seals the organic LED element and the dielectric film;
The dielectric layer has a thickness of 0.5 μm or more,
In the wavelength region of 450 nm to 650 nm, at least | n ₃ −n ₂ | ≦ 0.25 between the refractive index n _{1 of} the organic layer, the refractive index n _{2 of the} cathode, and the refractive index n ₃ of the dielectric film.
And | n ₁ −n ₂ | ≦ 0.20
An organic LED display device characterized in that the above relationship is established.   10. The organic LED display device according to claim 8, wherein the dielectric layer has a thickness of 0.5 μm to 2.0 μm.   The organic LED display device according to claim 10, wherein the dielectric layer has a thickness of 1.0 μm to 2.0 μm. In the wavelength region of 450 nm to 650 nm, the refractive index n _{1 of} the organic layer, the refractive index n _{2 of the} transparent electrode, and the refractive index n ₃ of the dielectric film,
| N ₃ −n ₂ | ≦ 0.20
And | n ₁ −n ₂ | ≦ 0.20
The organic LED display device according to claim 8, wherein the relationship is established.   The organic LED display device according to claim 8, wherein the dielectric film is composed of at least two elements selected from the group consisting of silicon, oxygen, nitrogen, and aluminum. The dielectric film is any one film selected from the group consisting of a SiO _x film, a Si _x N _y film, an AlN _x film, a SiO _x N _y film, an AlO _x N _y film, and a SiAlO _x N _y film. The organic LED display device according to claim 13.   The organic LED display device according to claim 8, wherein the organic layer emits white light. A transparent substrate;
A dielectric film having a thickness of 0.5 μm or more provided on the transparent substrate;
A transparent electrode film provided on the dielectric film;
In the wavelength range of 450 nm to 650 nm, between the refractive index _{n b} of the transparent electrode film and the refractive index _{n a} of the dielectric film,
| N _a −n _b | ≦ 0.25
An organic LED display device substrate characterized in that:   The organic LED display substrate according to claim 16, wherein the dielectric layer has a thickness of 0.5 μm to 2.0 μm.   The organic LED display device substrate according to claim 17, wherein the dielectric layer has a thickness of 1.0 μm to 2.0 μm. In the wavelength range of 450 nm to 650 nm, between the refractive index _{n b} of the transparent electrode film and the refractive index _{n a} of the dielectric film,
| N _a −n _b | ≦ 0.20
The organic LED display substrate according to any one of claims 16 to 18, wherein the relationship is established.   The said dielectric film is a board | substrate for organic LED element apparatuses of any one of Claims 16-19 comprised by the at least 2 element chosen from the group which consists of silicon, oxygen, nitrogen, and aluminum. The dielectric film is any one film selected from the group consisting of a SiO _x film, a Si _x N _y film, an AlN _x film, a SiO _x N _y film, an AlO _x N _y film, and a SiAlO _x N _y film. The organic LED display substrate according to claim 20.

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