JPH04237993A - Organic electroluminescence element and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an organic electroluminescence element having a wave guide path structure and the end face luminescence with low voltage and high intensity and obtain efficient manufacture thereof. CONSTITUTION:A wave guide path structure is constituted of a clad layer A5, a core layer 6 and a clad layer B7, and the refraction factor ns of the clad layer A5 which is a positive pole injection layer or a luminescent layer and the refraction factor nc of the clad layer B7 which is an electron injection layer or a luminescent layer are made smaller than the refraction factor nf of the core layer 6 which is a luminescent layer in an organic electroluminescence element.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an organic electroluminescent device and a method for manufacturing the same, and more specifically, an organic electroluminescent device having a waveguide structure and capable of emitting high-intensity edge emission at low voltage, and efficient manufacturing thereof. Regarding the method.

0002

[Prior art and problems to be solved by the invention] Conventionally,
Focusing on the high fluorescence efficiency of organic compounds, many studies have been conducted on devices that utilize the electroluminescence (EL) performance of organic compounds. For example, anode, hole injection layer,
An organic electroluminescent device (hereinafter referred to as an organic EL device) formed by stacking a light emitting layer and a cathode uses phthalocyanine as a hole injection layer, and a polymer such as polystyrene and an aromatic compound as a binder as a light emitting layer. The organic EL device used (see Japanese Patent Publication No. 64-7653) is disclosed. However, the refractive index was not set to form a cladding layer and a core layer within this device, and the light emitting layer (core layer) did not function as a waveguide. In addition, an organic EL element (Jpn. J. Appl. Phy. 27 (1
988) L713) also did not have a waveguide like the above element. On the other hand, as an EL element having an edge-emitting structure, an inorganic EL element (US Pat. No. 4,
535,341). This device uses a manganese-containing zinc sulfide in the phosphor layer and uses MISI.
M (metal/first insulating layer/semiconductor layer/second insulating layer/metal)
By adopting this structure and guiding light through the S layer (semiconductor layer), it was possible to increase the brightness by 30 to 40 times compared to the conventional one. However, this element requires a driving voltage of 200 V or more, which limits its usable range. In addition, an inorganic EL element (Japanese Unexamined Patent Application Publication No. 2-195679,
2-194976, 2-158361, etc.), but the luminescent materials that provide high brightness and high efficiency are manganese-containing zinc sulfide (emission color is yellow), terbinium-containing zinc sulfide compound ( The only emitted color is green), and it was difficult to realize many different emitted colors. Therefore, the present inventors have conducted extensive research to develop an organic EL element that has a waveguide and emits light with high brightness and high efficiency.

0003

[Means for solving the problem] As a result, it was discovered that high brightness, high efficiency light emission, and multicolor light emission are possible by using a waveguide structure consisting of a cladding layer and a core layer having a specific refractive index. Ta. The present invention was completed based on this knowledge. That is, the present invention provides an organic electroluminescent device and its production, characterized in that an anode, a hole injection zone, an electron injection zone, and a cathode are laminated in this order, and a waveguide structure is provided between the anode and the cathode. The present invention provides a method. Organic EL of the present invention
The elements are shown schematically in FIG. As shown in FIG. 1, the EL element of the present invention is formed by laminating an anode 1, a hole injection zone 2, an electron injection zone 3, and a cathode 4. Further, the hole injection zone 2 and the electron injection zone 3 can be divided into a cladding layer (A) 5, a core layer 6, and a cladding layer (B) 7 according to their optical functions, as shown in FIG.

[0004] The anode 1 in this organic EL element is preferably made of a metal, alloy, electrically conductive compound, or a mixture thereof having a large work function (4 eV or more). A specific example of such an electrode material is A.
Metals such as u, CuI, ITO, SnO2, ZnO
Examples include dielectric transparent materials such as. The anode is made by depositing these electrode materials by methods such as vapor deposition or sputtering.
It can be produced by forming a thin film. When emitting light from this electrode, reduce the transmittance to 10%.
It is desirable to make the resistance larger, and the sheet resistance of the electrode is preferably several hundred Ω/□ or less. Furthermore, although the film thickness depends on the material, it is usually 10 nm to 1 μm, preferably 10 nm to 1 μm.
-200 nm.

On the other hand, as the cathode 4, an electrode material made of a metal, alloy, electrically conductive compound, or a mixture thereof having a small work function (4 eV or less) is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium/copper mixture, Al/Al2O3, indium, and the like. The cathode can be manufactured by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. In addition, the sheet resistance of the electrode is preferably several hundred Ω/□ or less, and the film thickness is usually 10
~500 nm, preferably from 50 to 200 nm.

The hole injection zone 2 is a zone for transporting holes injected from the anode until the charges are recombined. This hole injection zone 2 may be only the hole injection layer itself, or in the case of a light emitting layer with high hole transportability (hole mobility is greater than electron mobility), the hole injection zone 2 may be formed at the anode of the light emitting layer. The area near the interface between the light emitting layer and other layers on the cathode side can become a hole injection zone. Therefore, the hole injection zone is either the hole injection layer only, the hole injection layer and the light emitting layer, or the light emitting layer only, and the hole injection zone does not need to coincide with the hole injection layer. However, if the electron injection zone does not include a light emitting layer, it is necessary that the hole injection zone has a light emitting layer. Electron injection zone 3
is a zone in which electrons injected from the cathode are transported until the charges are recombined. This electron injection zone 3 may be only the electron injection layer itself, or in the case of a light emitting layer with high electron transport properties (electron mobility is greater than hole mobility), the electron injection zone 3 may be formed from the cathode side of the light emitting layer to the anode side. The region up to the vicinity of the interface between the side light-emitting layer and other layers can become an electron injection zone. Therefore, the electron injection zone is either the electron injection layer only, the electron injection layer and the emissive layer, or the emissive layer only, and the electron injection zone does not need to coincide with the electron injection layer. However, if the hole injection zone does not include a light emitting layer, a light emitting layer needs to be present in the electron injection zone.

The cladding layer (A) 5 and the cladding layer (B) 7, which are part of the waveguide structure which is a feature of the present invention, are layers having a refractive index smaller than the refractive index of the core layer 6. Normally, in a laminated structure consisting of an anode/hole injection layer/light emitting layer/electron injection layer/cathode, the hole injection layer and the electron injection layer may be used as a cladding layer, and the core layer may be used as a light emitting layer. is not limited to this. For example, when the hole injection layer and the electron injection layer are made of known organic materials, it is difficult to make their refractive index smaller than the refractive index of the light emitting layer. In this case, for example, the hole injection layer is formed as a mixed layer of a hole injection material and a material with a small refractive index, and has a refractive index smaller than that of the core layer. This is the cladding layer manufacturing method that characterizes the present invention. Such a material with a small refractive index is
For example, a Teflon-based polymer, specifically a copolymer of tetrafluoroethylene and a mixture containing at least one comonomer, can be mentioned. Another example is MgF
Examples include alkali metal fluorides such as 2, SrF2, CaF2, and the like. This alkali metal fluoride has a refractive index of 1.
It is small at 5-1.3. In addition, the copolymer can be vapor-deposited, and by vapor-depositing and mixing it simultaneously with the hole-injecting material to form a cladding layer, a cladding layer with a refractive index smaller than that of the core layer and having hole-injecting properties can be obtained. I can do it. There are various known hole injection materials used here, and those conventionally known as materials for hole injection transport layers or hole injection layers may be used. The hole injection transport layer in the EL element is a layer made of a hole transport compound and has the function of transmitting holes injected from the anode to the light emitting layer. By interposing this hole injection transport layer between the anode and the light emitting layer, many holes can be injected into the light emitting layer with a lower electric field, and moreover, more holes can be injected into the light emitting layer from the cathode or the electron injection transport layer. The emitted electrons are accumulated near the interface within the light emitting layer due to the electron barrier existing at the interface between the light emitting layer and the hole injection transport layer, resulting in an element with excellent light emitting performance, such as improved light emitting efficiency. The hole transport compound used in the hole injection transport layer is arranged between two electrodes to which an electric field is applied, and when holes are injected from the anode, the hole transport compound is capable of appropriately transmitting the holes to the light emitting layer. Compounds with a molecular weight of 104 to 10
At least 10-6 cm when an electric field of 6 V/cm is applied.
A material having a hole mobility of 2/V·sec is suitable.

[0008] Such hole transport compounds are not particularly limited as long as they have the above-mentioned preferable properties, and include those conventionally used as charge transport materials for holes in photoconductive materials and those used in EL devices. Any material can be selected from among the known materials used for the hole injection transport layer. Examples of the charge transport material include triazole derivatives (described in U.S. Pat. No. 3,112,197, etc.) and oxadiazole derivatives (described in U.S. Pat. No. 3,189,447, etc.). )
, imidazole derivatives (described in Japanese Patent Publication No. 37-16096, etc.), polyarylalkane derivatives (U.S. Pat. Nos. 3,615,402 and 3,82)
Specification No. 0,989, Specification No. 3,542,544, Japanese Patent Publication No. 45-555, Japanese Patent Publication No. 51-10983, Japanese Patent Publication No. 93224/1983, Japanese Patent Publication No. 55-1710
Publication No. 5, Publication No. 56-4148, Publication No. 55-1086
Publication No. 67, Publication No. 55-156953, Publication No. 56-
36656), pyrazoline derivatives and pyrazolone derivatives (U.S. Pat. No. 3,180,7)
Specification No. 29, Specification No. 4,278,746, Japanese Unexamined Patent Publication No. 55-88064, Japanese Patent Application Publication No. 55-88065, Japanese Patent Application No. 49-105537, Japanese Patent Application Laid-open No. 55-51086.
No. 56-80051, No. 56-8814
Publication No. 1, Publication No. 57-45545, Publication No. 54-1
No. 12637, No. 55-74546, etc.), phenylenediamine derivatives (U.S. Pat. No. 3,615,404, Japanese Patent Publication No. 51-1010)
Publication No. 5, Publication No. 46-3712, Publication No. 47-253
No. 36, JP-A No. 54-53435, JP-A No. 54-534-
110536, U.S. Pat. No. 54-119925, etc.), arylamine derivatives (U.S. Pat. No. 3,567,450, U.S. Pat. No. 3,180,70)
Specification No. 3, Specification No. 3,240,597, No. 3
, 658,520, 4,232,103, 4,175,961, 4,0
Specification No. 12,376, Japanese Patent Publication No. 49-35702, Japanese Patent Publication No. 36-27577, Japanese Patent Publication No. 14425-1988
No. 0 Publication, No. 56-119132, No. 56-
22437, West German Patent No. 1,110,518, etc.), amino-substituted chalcone derivatives (described in U.S. Pat. No. 3,526,501, etc.), oxazole derivatives (U.S. Pat. 3rd, 25th
7,203, etc.), styryl anthracene derivatives (described in JP-A-56-46234, etc.), fluorenone derivatives (JP-A-54-11),
0837, etc.), hydrazone derivatives (U.S. Pat. No. 3,717,462, JP-A-54-59143, JP-A-55-52063,
55-52064, 55-46760, 55-85495, 57-11350, 57-148749, etc.), stilbene derivatives (Japanese Unexamined Patent Publication No. 61 -21036
No. 3 Publication, No. 61-228451, No. 61-
No. 14642, No. 61-72255, No. 62
-47646 publication, 62-36674 publication, 62-36674 publication, same 6
No. 2-10652, No. 62-30255, No. 60-93445, No. 60-94462,
Publication No. 60-174749, No. 60-175052
Examples include those described in the No. 1 gazette, etc.). In the present invention, these compounds can be used as hole transfer compounds, but the following porphyrin compounds (described in JP-A No. 63-295695 etc.), aromatic tertiary amine compounds and Styrylamine compounds (U.S. Pat. No. 4,127,412,
JP-A No. 53-27033, JP-A No. 54-58445, JP-A No. 54-149634, JP-A No. 54-642
Publication No. 99, Publication No. 55-79450, Publication No. 55-14
4250, No. 56-119132, No. 61-295558, No. 61-98353, No. 63-295695, etc.)
In particular, it is preferable to use the aromatic tertiary amine compound.

Representative examples of the porphyrin compounds include:
Polyfin, 1,10,15,20-tetraphenyl-21H,23H-porphine copper(II), 1,
10, 15, 20-tetraphenyl-21H,
23H-porphine zinc (II), 5, 10, 1
5,20-tetrakis(pentafluorophenyl)
-21H, 23H-porphine, silicon phthalocyanine oxide, aluminum phthalocyanine chloride,
Phthalocyanine (metal-free), dilithium phthalocyanine, copper tetramethyl phthalocyanine, copper phthalocyanine,
Examples include chromium phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium phthalocyanine oxide, magnesium phthalocyanine, and copper octamethyl phthalocyanine. Further, representative examples of the aromatic tertiary amine compound and styrylamine compound include N,N,N', N'-tetraphenyl-4,4'-diaminobiphenyl, N,
N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diaminobiphenyl, 2,2-bis(4-di-p-tolylaminophenyl)propane, 1
, 1-bis(4-di-p-tolylaminophenyl)cyclohexane, N,N,N',N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis(
4-di-p-tolylaminophenyl)-4-phenylcyclohexane, bis(4-dimethylamino-2-methylphenyl)phenylmethane, bis(4-di-p-tolylaminophenyl)phenylmethane, N,N'-diphenyl-N,N'-di(4-methoxyphenyl)-4,
4'-diaminobiphenyl,N,N,N',N'-
Tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis(diphenylamino)quadriphenyl, N,N,N-tri(p-tolyl)amine,
4-(di-p-tolylamino)-4'-[4-(di-
p-tolylamino)styryl]stilbene, 4-N,N
Examples include -diphenylamino-(2-diphenylvinyl)benzene, 3-methoxy-4'-N,N-diphenylaminostilbene, and N-phenylcarbazole. The hole injection transport layer in the EL device of the present invention may be composed of a single layer composed of one or more of these hole transport compounds, or may be composed of a compound different from the above layer. A stack of hole injection transport layers may also be used. Furthermore, there are various known electron injection materials, and those conventionally known as materials for electron injection transport layers or electron injection layers are used. The electron injection transport layer is made of an electron transport compound and has a function of transporting electrons injected from the cathode to the light emitting layer. There are no particular limitations on such electron transfer compounds, and any one can be selected and used from conventionally known compounds. Preferred examples of the electron transfer compound include:

0010

[Chemical formula 1]

Nitro-substituted fluorenone derivatives such as

[
0012

[Case 2]

Thiopyrane dioxide derivatives such as

0
014]

[Chemical formula 3]

Diphenylquinone derivatives such as (t-Bu: tert-butyl group) [described in Polymer Preprints, Japan, Vol. 37, No. 3, p. 681 (1988), etc. things], or

[0016]

[C4]

Compounds such as [Japanese Journal of Applied Physics (J.J. App
l. Phys. )” Volume 27, L269 (198
8)] and anthraquinodimethane derivatives (JP-A-57-149259, JP-A-57-149259),
No. 55450, No. 61-225151, No. 61-233750, No. 63-104061
(described in JP-A-60-69657, JP-A-61-143)
No. 764, No. 61-148159, etc.), anthrone derivatives (Japanese Unexamined Patent Publication No. 61-225)
151 Publication, Publication No. 61-233750, etc.),

[0018]

[C5]

Examples include oxadiazole derivatives disclosed in "App. Phys. Lett.", Vol. 55, p. 1489 (1989). Further, a hole injection material made of inorganic materials such as p-type α-Si and p-type α-SiC, and an electron injection material made of n-type α-Si and n-type α-SiC can be used as the charge injection material. Examples include inorganic semiconductors disclosed in International Publication WO90/05998. On the other hand, there are various known luminescent materials, such as 3-(2'-N
-Methylbenzimidazolyl)-7-N,N-diethylaminocoumarin (coumarin 30) (see Japanese Patent Application No. 1-009995), phthaloperinone (J. Appl. Phys. Vol. 27, L71)
3 (1988)), benzoxazolyl or benzthiazole-based compounds (see JP-A-59-194393), metal chelated oxinoid compounds (see JP-A-63-1943),
295695), stilbene compounds (EP0
319881 or EP0373582) and perylene compounds. The at least one comonomer used here is not limited as long as it is a comonomer that can be copolymerized with tetrafluoroethylene to form a copolymer, but the following formula

[0020]

[C6]

[0021] (In the above formula (■), X, X' are F, C
1 or H, which may be the same or different. Moreover, R is -CF=CF- or

[0022]

[C7]

(R', R'' are F, Cl, -COF, alkyl group-substituted oxycarbonyl group, alkyl group, perfluorinated alkyl group, hydrogen-containing fluorinated alkyl group (alkyl group has 1 to 6 carbon atoms) ) are preferred. Particularly preferred comonomers of the formula (2) include the following formula (1).

[0024]

[Chemical formula 8]

(In the above formula (■), X=X'=F,
R=

[0026]

[Chemical formula 9]

Comonomer represented by (R'=R''=CF3), the following formula ■

[0028]

[Chemical formula 10]

(In the above formula (■), X=X'=F,
R=

[0030]

[Chemical formula 11]

(R’=R”=F)) A comonomer represented by the following formula■

[0032]

[Chemical formula 12]

(In the above formula (■), X=X'=F, R=
A comonomer represented by -CF=CF-) can be mentioned. The above formula■
The content of the comonomer represented by is 0.01 to 99% based on the total amount of tetrafluoroethylene and this comonomer.
Weight percent is preferred. Particularly preferably 11 to 80% by weight
It is. In addition, other comonomers include ethylene; 1
-butene; isobutylene; trifluoropropene; trifluoroethylene; olefin comonomers such as chlorotrifluoroethylene; vinyl fluoride; vinyl comonomers such as vinylidene fluoride; perfluoropropene; perfluoro(alkyl vinyl ether); methyl 3-(1 −
(difluoro-((trifluoroethenyl)oxy)methyl)-1,2,2,2-tetrafluoroethoxy)-
2,2,3,3-tetrafluoropropanoate; 3-
(1-(difluoro-((trifluoroethenyl)oxy)methyl)-1,2,2,2-tetrafluoroethoxy)-2,2,3,3-tetrafluoropropionate; 2-(1-( Examples include perfluoro comonomers such as difluoro-((trifluoroethenyl)oxy)methyl)-1,2,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoroethanesulfonyl fluoride. The content of the above comonomer is preferably 0.005 to 30% by weight, particularly 1 to 15% by weight, based on the total amount of tetrafluoroethylene and the comonomer represented by the formula (2). In addition, the above comonomer is represented by the above formula ■
When used in combination with a comonomer represented by formula (2), it is preferable that the content of the comonomer is the minimum among the contents of tetrafluoroethylene, the comonomer represented by the formula (2), and the comonomer described above. Furthermore, inorganic materials with a low refractive index such as alkali metal fluorides can be easily deposited in a vacuum chamber by resistance heating or electron beam heating. Therefore, a new cladding layer can be formed by co-deposition of the organic material forming the cladding layer and the above-mentioned low refractive index inorganic material.

The mixing ratio of the hole-injecting material or electron-injecting material (charge-injecting material) and the material with a small refractive index is arbitrary, but from the viewpoint of the charge-injecting material, the mixing ratio of the charge-injecting material is 30% by weight. % or more is preferable. When selecting the mixing ratio of the charge injection material, consideration should be given to the experimental results of hole mobility that depends on the mixing ratio of the polymer and hole injection material in the photoreceptor (Philos.
．． B53, 193 (1986), etc.). According to the method for producing a cladding layer as described above, the refractive index of the obtained cladding layer is, for example, that the refractive index of the organic charge injection material is usually 1.
45 to 1.6, and the refractive index of the low refractive material is Teflon A.
1.29 to 1.32 for F, 1 for MgF2
．． Since it is 38, it is an intermediate value between the two. The simplest method for estimating the refractive index of such a cladding layer is the following formula: cladding layer = (refractive index of charge injection material) x (wt%)
/100+(refractive index of low refractive material)×(weight%)/10
Although it is estimated as 0 on a weight average basis, only an approximate value can be obtained because it is affected by the denseness of the film that becomes the cladding layer. When the cladding layer consists of only a thin film, it is preferable to measure the refractive index using a known refractive index measurement technique (such as an ellipsometer) and design the waveguide.

The core layer 6 may serve as a light emitting layer in one embodiment of the EL device of the present invention. When the light-emitting layer is used as a core layer, since the light-emitting material is an organic material, the refractive index is 1.4 to 1.6. Therefore, the refractive index of the cladding layer may be made smaller than the refractive index of the core layer using the cladding layer formation technique described above. In particular, when it is desired to increase the refractive index of the core layer, the core layer may be formed by co-evaporating an inorganic material with a high refractive index and a luminescent material, for example. Inorganic materials used at this time include, for example, As2 S3, As40S1
0, S40Ge10 etc. chalcogenoid glass (refractive index 2.2-2.4), ZnO, Nb2O5, Ta2
Metal oxides and nitrides (refractive index 1.9 to 2.3) such as O5, Si3 N4, TiO2, InP, Ga
Semiconductor systems such as As, CdS, Ge, ZnS (refractive index 2.
8 to 4.1). Preferably, ZnO, Nb2O5, Ta, which has high transparency and does not absorb EL emission.
An oxide material such as 2 O5 is preferable. The above-mentioned inorganic material can be easily deposited by an electron beam evaporation method and a reactive evaporation method in which oxygen and metal are deposited while reacting in a vacuum chamber at the same time as the luminescent material is deposited. By combining an organic light-emitting material and an inorganic material in this way, a core layer with a high refractive index can be formed.

In the cladding layer and core layer obtained as described above, the cladding layer usually functions as a charge injection layer and the core layer functions as a light emitting layer, but other cases are also possible. For example, the light emitting layer may function as both a cladding layer and a core layer, and the hole injection layer may function as a cladding layer. At this time, the EL element is produced by depositing a luminescent material alone on the hole injection layer formed as a cladding layer to form a luminescent layer (core layer), and then co-evaporating the luminescent material and a low refractive index material to form a cladding layer. It can be obtained by forming a light emitting layer. Furthermore, it is also possible to form a laminated function of a cladding layer, a core layer, and a cladding layer within a single layer of the hole injection layer. In this way, the cladding layer, core layer,
The optical laminated structure of the cladding layer can be formed separately from the electrical element structure including the hole injection layer, the light emitting layer, and the electron injection layer.

Next, the operation and mechanism of the organic EL device of the present invention will be explained. FIG. 2 shows an organic EL device comprising an anode 1, a cladding layer 5 as a hole injection layer, a light emitting layer 6, a cladding layer 7 as an electron injection layer, and a cathode 4. By applying a voltage necessary for light emission to the anode and cathode of this organic EL element, a waveguide mode (TEn, TMn, n=0,1 ,2,
3...) are confined and propagated. This waveguide mode is not arbitrarily realized in the waveguide structure of FIG. 3, but must satisfy the following conditions. An organic EL device that satisfies this condition is the organic EL device having the waveguide structure of the present invention. Conventionally, an element having a three-layer structure consisting of a hole injection layer 9, a light emitting layer 10, and an electron injection layer 11 as shown in FIG. 4 has been known, but it did not have a waveguide structure. An element having a waveguide structure can only be obtained according to the present invention by satisfying the following conditions. The first condition is for the refractive index nS of the cladding layer which is the hole injection layer or the light emitting layer, the refractive index nC of the cladding layer which is the electron injection layer or the light emitting layer, and the refractive index nf of the light emitting layer which is the core layer. , nf > nS and nf >
nC
...(α). The second condition is at least 1
There are two TE modes (ie TE0). That is, V(1-b)1/2 = π-tan -1((1-b)/b)1/2 -ta
n −1((1−b)/(b+a))1/2


. . . θ that satisfies (β) exists for D (thickness of the core layer) and the wavelength λ of the light to be guided. Here, V, a, b
is as follows. V=(2π/λ)D(nf2-ns2)1/2
...(γ)b=(nf 2 sin2 θ−n
s2)/(nf2-ns2)
...(δ)a=(ns2-nc2)/(nf
2-ns 2)
...(ε)

At this time, if the two cladding layers have different refractive indices, the asymmetry measure a is not zero. Therefore, D has a lower limit value. More precisely, the lower limit value of D such that θ in equation (β) holds is determined for the wavelength λ to be introduced. For two cladding layers formed of organic matter, a is easily 0.3
It can be more than that. Therefore, in order to satisfy the second condition, D is preferably 10 nm or more, and particularly preferably 50 nm or more, although it is not particularly limited. Furthermore, the asymmetry scale a is preferably 1 or less. If the asymmetry measure a is greater than 1, the formula (β)
From 0.75> V=(2π/λ)D(nf 2 −ns
2) 1/2, and at this time even the TE0 mode no longer exists. However, with respect to the refractive indexes ns and nf of the cladding layer and core layer formed of organic materials, ns > 1.3, nf < 1.6 and ns
<nf, so in the range of 800>λ>400 (nm) and 100>D (nm), there can easily be a case of 0.75>V. As a specific example, Table 1 shows the values of V when nf = 1.5, ns = 1.4, and a = 1.

[0039]

[Table 1]

From Table 1, the value of V under the above conditions is 0.
．． 75 in many cases, and there is a high possibility that no waveguide mode exists. On the other hand, if D can be made larger than 100 nm, the restrictions on a are significantly relaxed. In fact, the larger D is, the greater the number of waveguide modes, which is preferable, but when considering the luminance and electrical efficiency of the organic EL element, it is preferably 1 μm or less in order to obtain a good value. In particular, the thickness is preferably 200 nm or less. Furthermore, if it is desired to make D thinner, the difference in refractive index between the core layer and the cladding layer may be increased. In this case, for example, by using a complex of inorganic and organic materials with a high refractive index in the core layer,
The value of a becomes smaller, making it possible to lower the lower limit of D. On the other hand, the thickness of the cladding layer is set so that the electric field strength of the guided light transmitted through the cladding layer does not reach outside the cladding layer. For example, the penetration depth d for a cladding layer with a refractive index ns is d=(λ/2π)/(N2 −n
s 2 ) 1/2 (N=nf sin θ). Here, since d=(λ/2π)/(N2-ns2)1/2, it is preferable to evaluate the value of d and set the film thickness of the cladding layer to exceed d. Generally d is 80
It is about nm. Furthermore, especially when the value of D is small, the propagation loss due to the metal that is the electrode is large. For example, D is 0
．． When the thickness is 1 μm, when the core layer is brought into direct contact with the metal electrode, it is 102 dB/cm, TM in TE0 mode.
In the 0 mode, the signal is attenuated by about 103 dB/cm and becomes unable to propagate. As described above, it is necessary to provide a cladding layer between the metal electrode and the core layer in order to have a waveguide structure, and this is also one of the features of the present invention.

Next, an example of a preferred method for manufacturing the organic EL device of the present invention will be explained. Organic E shown in Figure 4
To explain the method for manufacturing the L element, first, the substrate 8 is cleaned using a known detergent (organic carbon is removed by UV ozone cleaning), isopropanol, etc., and dried. A thin film made of a desired electrode material, for example, an anode material, is
The anode 1 is manufactured by forming the anode 1 by a method such as vapor deposition or sputtering so as to have a thickness in the range of μm or less, preferably in the range of 50 to 200 nm. Next, a hole injection material and a material with a small refractive index (a Teflon-based polymer or an alkali metal fluoride, preferably a copolymer such as Teflon AF or MgF2) are co-evaporated onto the hole injection layer 5.
will be established. The deposition conditions for the hole injection material vary depending on the type of compound used, the desired crystal structure and association structure of the deposited film, but generally the boat heating temperature is 200 to 450°C.
, degree of vacuum 10-3 to 10-5 Pa, deposition rate 0.05
~1nm/sec, substrate temperature 100℃ or less, film thickness 5nm
~5000 nm (particularly preferably 20 nm ~ 200 nm)
) is desirable. Next, a luminescent material is vapor-deposited thereon to provide a luminescent layer 6. The deposition conditions vary depending on the type of compound used, the desired crystal structure and association structure of the deposited film, but generally the boat heating temperature is 200 to 400°C, the degree of vacuum is 10-4 to 10-5 Pa,
Vapor deposition rate 0.05-1 nm/sec, substrate temperature 100°C
Below, the film thickness is 5 nm to 1000 nm (particularly preferably 20 nm to 1000 nm).
It is desirable to select the thickness appropriately within the range of 200 nm to 200 nm. Next, an electron injection material and a material with a small refractive index (
A Teflon-based polymer (preferably a copolymer such as Teflon AF) is co-evaporated to form the electron injection layer 7. The deposition conditions vary depending on the type of compound used, the desired crystal structure and association structure of the deposited film, but generally the boat heating temperature is 200 to 450°C, and the degree of vacuum is 10-4 to 1.
It is desirable to appropriately select the following values: 0-5 Pa, a deposition rate of 0.05-1 nm/sec, a substrate temperature of 100° C. or less, and a film thickness of 20 nm to 2000 nm (particularly preferably 50 nm to 200 nm). Next, after forming this light-emitting layer, a thin film made of a cathode substance is formed thereon by a method such as vapor deposition or sputtering to a thickness in the range of 10 to 500 nm, preferably 50 to 200 nm, By providing the cathode 4, a desired EL element can be obtained. Note that in manufacturing this organic EL element, it is also possible to reverse the manufacturing order and manufacture the cathode, electron injection layer, light emitting layer, hole injection layer, and anode in this order.

[0042] In addition, an organic E consisting of a cladding layer (hole injection layer), a core layer (light emitting layer) and a cladding layer (light emitting layer)
L elements are also possible. The method for manufacturing this organic EL element is as follows:
The only difference in structure from that in FIG. 1 is the light-emitting layer, which is a cladding layer, and the rest is the same as in FIG. 1. The light-emitting layer, which is a cladding layer, can be provided by co-evaporating a light-emitting material and a material with a small refractive index (a Teflon-based polymer, preferably a copolymer such as Teflon AF). For the vapor deposition conditions, the vapor deposition conditions for the luminescent material described above can be referred to. When applying a DC voltage to the EL element obtained in this way, the anode is set to + and the cathode is set to - and the voltage is 5.
When approximately 40 V is applied, light emission can be observed from the light emitting end face. Furthermore, even if a voltage with the opposite polarity is applied, no current flows and no light is emitted at all. Furthermore, when applying an alternating voltage, light is emitted only when the anode is in a positive state and the cathode is in a negative state. Note that the waveform of the applied alternating current may be arbitrary.

[0043]

EXAMPLES Next, the present invention will be explained in more detail by way of examples. Example 1 ITO was formed into a 100 nm thick film by vapor deposition on a 75 mm x 25 mm x 1 mm glass substrate (HOYA
Co., Ltd.) was used as a transparent support plate. This transparent support plate was subjected to ultrasonic cleaning in the following order: propyl alcohol, pure water, and isopropyl alcohol, and then dry nitrogen was blown to remove the solvent from the substrate surface. The substrate after cleaning in the above process is treated with UV/O3 dry stripper (product name: UV30).
0, manufactured by Samco International) for 3 minutes to remove organic substances on the surface of the substrate. It was fixed to a substrate holder of a commercially available vacuum evaporation device (manufactured by ULVAC Co., Ltd.). TPD shown in the following formula (■) is a hole injection material, and aluminum trioxin (Al(
Ox) 3) and Teflon AF (manufactured by DuPont, Inc.), a low refractive index material for forming the cladding layer, were placed in separate molybdenum resistance heating boats, attached to current terminals, and heated under vacuum. The tank was set to 10-4 Pa. First, electricity was applied to a boat containing TPD and a boat containing Teflon AF, and simultaneous vapor deposition was performed at a vapor deposition rate of 3 angstroms/second for each. As a result, a cladding layer (thickness: 120 nm) serving as a hole injection layer was formed. Next, the boat containing Al(Ox)3 was energized, and the core layer (thickness 15
0 nm) was formed. Next, electricity was applied to the boat containing Teflon AF and the boat containing Al(Ox)3, and simultaneous vapor deposition was performed at a vapor deposition rate of 3 angstroms/second for each. As a result, a cladding layer (thickness 120 nm) which is a light emitting layer is formed.
m) was formed. Thereafter, the vacuum chamber was opened and a stainless steel mask was placed over the lamination of the substrate, cladding layer, core layer, and cladding layer. The opening of this mask is 1 cm x 2.5 cm, and the excitation area (the area that is excited at the end surface of the light emitting layer)
has been established. Furthermore, magnesium was placed in a molybdenum boat, silver was placed in a heating filament, and a vacuum chamber was opened for 1 hour.
The pressure was set to 0-4Pa. Electricity was applied to the boat and filament to simultaneously deposit magnesium at a deposition rate of 14 angstroms/second and silver at a deposition rate of 0.6 to 0.9 angstroms/second to form a magnesium-silver electrode. Next, the organic EL element was taken out from the vacuum chamber, and the glass substrate was broken with a glass cutter. At this time,
The long direction of the excitation magnesium and silver electrodes was cut and broken to make the excitation electrodes 1 cm x 2 cm. This determined the direction in which light was emitted from the end face of the light emitting layer.

[0044]

[Chemical formula 13]

[0045]

[Chemical formula 14]

I of the organic EL device manufactured as described above
When a voltage of 15 volts was applied using TO as the anode and the magnesium and silver electrodes as the cathode, high-intensity green light was emitted from the light-emitting end face. Next, the light-emitting end face was adhered to the light-receiving part of the photodiode, and the light-emitting surface of the photodiode other than the adhesive part was covered with black tape to prevent light from entering. Additionally, black tape was attached to the edge of the substrate to prevent the photodiode from receiving light through the substrate. When a voltage of 15 volts was applied to the organic EL element thus constructed, the organic EL element
It was confirmed that a current of 50 mA/cm2 flowed through the L element and 0.01 mW was output from the photodiode. This corresponds to 100 mW/cm2 and when converted into brightness, it becomes a high brightness of about 100,000 cd/m2. Usually ITO
Since the luminance of the side light emitting surface is 1000 cd/m2,
This means that the edge-emitting device of the present invention has achieved brightness 100 times that amount.

Example 2 When forming a core layer, which is a light-emitting layer made of Al(Ox)3, a doping material of DCM (laser dye, Kodak Company) was simultaneously vapor-deposited so that the amount of the vapor deposited
It was manufactured and evaluated in the same manner as in Example 1, except that x)3 was approximately 1/100 of that of 3. As a result, linear, high-intensity orange light emission was obtained from the light-emitting end face. The output at this time was 0.03 mW, and the brightness was extremely high at 140,000 cd/m2.

Example 3 A device was produced and evaluated in the same manner as in Example 2, except that the doping material was changed to another fluorescent dye, Coumarin 30 (Lambda Physics). As a result, linear, high-intensity blue-green light emission was obtained from the light-emitting end face.

Example 4 The cladding layer, core layer and TPD single layer produced in Example 1 were individually formed into a film on a glass substrate, and the refractive index was determined using an ellipsometer. The results are shown in Table 2.

[0050]

[Table 2]

As can be seen from Table 2, the refractive index of the cladding layer was smaller than the refractive index of the core layer. At this time, the asymmetry measure a had a value extremely close to 0. Also,
In the case of the core layer (film thickness 150 nm) of Examples 1 and 2,
It was confirmed that there is a θ that satisfies the second condition for having the above waveguide structure. Further, the penetration depth of the electric field into the cladding layer was calculated to be approximately 110 nm, and from this value it was found that the thickness of the cladding layer in Example 1 was increased to prevent propagation loss due to the metal electrode.

Example 5 A product was produced and evaluated in the same manner as in Example 1, except that MgF2, an inorganic material, was used instead of Teflon AF, which was co-deposited with TPD, and a cladding layer was formed by electron beam co-evaporation. Ta. As a result, when 18V was applied, the brightness was 16
It had an ultra-high brightness of 10,000 cd/m2.

[0053]

[Effects of the Invention] As described above, the organic EL device of the present invention has
By using a waveguide structure consisting of a cladding layer and a core layer with a specific refractive index, edge emission was obtained, making it possible to achieve high brightness, highly efficient light emission, and multicolor light emission at low voltage. Therefore, the organic EL device of the present invention can be effectively used for laser oscillation, etc., as it allows light to be confined by the waveguide structure.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a multilayer structure of an organic EL element.

FIG. 2 is a schematic diagram showing the configuration of a waveguide structure.

FIG. 3 is a schematic diagram showing a waveguide structure.

FIG. 4 is a schematic diagram showing a conventional organic EL element.

[Explanation of symbols]

1 Anode 2 Hole injection zone 3 Electron injection band 4 Cathode 5 Clad layer (A) 6 Core layer 7 Clad layer (B) 8 Board 9 Hole injection layer 10 Luminescent layer 11 Electron injection layer

Claims (6)

[Claims] [Claim 1] Anode, hole injection zone, electron injection zone,
An organic electroluminescent device characterized in that cathodes are laminated in this order and a waveguide structure is provided between the anode and the cathode. 2. The hole injection zone functions as a hole injection layer or a hole injection layer and a light emitting layer, and the electron injection zone functions as an electron injection layer or an electron injection layer and a light emitting layer. Item 1. The organic electroluminescent device according to item 1. 3. The waveguide structure has a structure in which a cladding layer (A), a core layer, and a cladding layer (B) are laminated in order from the anode to the cathode, and the cladding layer (A), which is a hole injection layer or a light emitting layer ( The refractive index nS of A) or the refractive index nC of the cladding layer (B) which is the electron injection layer or the light emitting layer is smaller than the refractive index nf of the light emitting layer which is the core layer, and the thickness D of the core layer and the waveguide 3. The organic electroluminescent device according to claim 2, wherein the wavelength λ of the emitted light of the organic electroluminescent device is set such that at least one incident angle θ that satisfies the following formula (I) exists. . (2π/λ)D(nf 2 −nf 2 sin2
θ) 1/2=π-tan-1((nf 2 -nf
2 sin2 θ) /(nf 2 sin2 θ−
ns 2 )) 1/2 -tan-1((nf 2 -
nf 2 sin2 θ) /(nf 2 sin2
θ-nc 2 )) 1/2

...(I) 4. The organic electroluminescent device according to claim 3, wherein at least one mode is determined to be guided through the core layer in the waveguide structure. 5. The thickness of the cladding layer is determined by the following formula: d>(λ/2π)/(nf 2 sin2
θ−ns 2 ) 1/2 or d>(λ
/2π)/(nf2sin2θ-nc2)1
4. The organic electroluminescent device according to claim 3, wherein the organic electroluminescent device satisfies the following. 6. Claim 3, wherein the cladding layer is formed as a mixed layer by depositing a depositable material with a low refractive index and a depositable material with a higher refractive index than the deposited material.
A method for manufacturing an organic electroluminescent device.