JP2003317931A - El element and display using thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EL (electroluminescence) element efficiently taking out light to the device outside and to provide an EL display improving the brightness and reducing the power consumption. <P>SOLUTION: This EL element and the EL display are so constituted that a condensing structure substantially narrowing a light emission area is provided between a light emitting layer and a whole reflection suppressing structure and, at least, the refractive index of the condensing structure out of materials constituting the whole reflection suppressing structure and the condensing structure is more than the refractive index of the material constituting the light emitting layer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL (Electro Luminescence).
element) and a display device using the element.

[0002]

2. Description of the Related Art An organic EL device is a light emitting device that operates by injecting electrons and holes from an electrode into an organic phosphor and exciting a luminescent center by the recombination energy of the electrons and holes.

The structure of the organic EL element is a sandwich structure in which a light emitting layer is sandwiched by electrodes, but a planar light emitting element can be obtained by making at least one of the electrodes transparent.

FIG. 12 is a schematic view for explaining the structure of a very simple organic EL element. In this schematic diagram, only the back electrode, the organic light emitting layer, the transparent electrode, and the glass substrate are shown, but in the actual device, various thin film layers such as an electron transport layer and a hole transport layer are laminated. Has been done. By applying a voltage between the back electrode and the transparent electrode, light emission occurs in the organic light emitting layer, and the light is extracted from the transparent electrode side to the outside of the element.

The light emitted from the organic light emitting layer is emitted to the outside of the device (for example, in the air) through the transparent electrode and the glass substrate. Generally, the refractive index of the material used for the organic light emitting material, the transparent electrode and the glass substrate. Is different. Therefore, a light extraction loss due to Fresnel reflection occurs at the interface where the first material (refractive index: n1) having a different refractive index and the second material (refractive index: n2) are in contact with each other. The Fresnel reflection can be expressed by using the refractive index of the material. For example, in the case of normal incidence, it is expressed by the following formula.

R = {(n1-n2) / (n1 + n2)} ² R: Fresnel reflectance n1: Refractive index of material 1 n2: Refractive index of material 2 Further, for the incident side material (refractive index: ni) When the exit side material (refractive index: ns) has a low refractive index, that is, ni
When> ns, total reflection occurs with respect to light incident at an angle of total reflection or more (FIG. 13). Critical angle θc at which total internal reflection occurs
Is expressed by the following formula.

Θc = arcsin (ns / ni) θc: Critical angle of total reflection ni: Refractive index of material on incident side ns: Refractive index of material on exit side Total reflection occurs for light incident at an angle larger than θc. Ignoring the absorption of the material, 100% reflection occurs. Therefore, a large loss occurs when the light is extracted to the outside of the device. In fact, when a glass flat plate is used as a substrate, the light extraction efficiency that is extracted to the outside is about 20% or less.

There are some reported examples of methods for improving the light extraction efficiency to the outside of the device.

For example, it has been proposed to provide a microlens on the element substrate to improve the light extraction efficiency to the outside of the element (for example, Japanese Patent No. 2773720) (FIG. 1).
4). In order to effectively suppress total reflection that occurs at the interface with air, it is necessary to have a lens diameter that is sufficiently large with respect to the light emitting area. However, in the conventional configuration, it is difficult to provide a lens having a sufficiently large diameter with respect to the light emitting area in the element, and thus it is not possible to obtain a sufficient total reflection suppressing effect. In particular, for device applications aiming to realize high-definition pixel size such as for display applications, it is necessary to provide a lens that is sufficiently large for the pixel area because physical interference between microlenses between pixels and pixel density increase. It is disadvantageous from the point of view.

In Japanese Patent Laid-Open No. 2000-260559,
A structure using an aggregate of optical fibers as a substrate has been proposed for the purpose of providing an element capable of extracting light emitted from an organic EL element passing through the substrate with high efficiency.
Since the optical fiber is used as a member for the purpose of guiding light, there is a problem that the aperture area becomes small and a light amount loss occurs.

Further, in Japanese Unexamined Patent Publication No. 2000-284726, for the purpose of providing a display device in which the intensity of light in a specific direction is increased and the light can be used efficiently and in a wide viewing angle, A structure having a directional member such as a resonator structure having a multilayer thin film structure, which has a periodic refractive index distribution in a direction, and a scattering member such as a microlens array has been proposed. In the embodiment, the structure is provided as a structure for strengthening directivity such as a resonator structure, and a scattering member such as a microlens is provided in order to improve the viewing angle, but a microlens sufficiently large for the light emitting area is provided. It was difficult to improve the extraction efficiency.

Japanese Unexamined Patent Publication (Kokai) No. 7-37688 proposes the use of a substrate having a columnar high refractive index portion for the purpose of reducing the viewing angle dependency and making the display highly vivid and bright. The section is not provided to reduce the substantial light emitting area, and is not provided with a structure for suppressing total reflection.

In Japanese Patent Laid-Open No. 11-265791, a structure or island having a light transmitting hole that reflects internal light and absorbs external light in order to realize an EL display device which suppresses reflection of external light and has a good contrast. Although a structure has been proposed, it has been insufficient to efficiently extract light because there is no device for suppressing the total reflection that occurs at the interface between the substrate and air.

[0014]

In view of the above problems, the present inventor has focused on suppressing the total reflection that occurs at the interface between the element and air. Further, attention was paid to the refractive index of the organic light emitting layer and the refractive index of the medium through which the light emitted from the organic light emitting layer passes when the light emitted from the organic light emitting layer goes out of the light emitting device.

An object of the present invention is to effectively extract light to the outside of the device and to realize high visibility as a display device.

[0016]

Therefore, the present invention has a transparent electrode provided on the light extraction surface side and a back electrode provided so as to face the transparent electrode, and comprises the transparent electrode and the back electrode. An EL device having a light emitting layer therebetween, wherein a total reflection suppressing structure is provided on the light extraction surface side, and a light emitting area is substantially provided between the light emitting layer and the total reflection suppressing structure. A condensing structure for squeezing is provided, and at least the refractive index of the condensing structure among the materials forming the total reflection suppressing structure and the condensing structure is equal to or higher than the refractive index of the material forming the light emitting layer. Provided is a characteristic EL device.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an EL device (electroluminescence device :: Electro Lumines).
cence element). In the present embodiment, an organic EL element will be described as an example as described later, but the present invention may be an inorganic EL element.

A description will be given below with reference to FIG.

FIG. 1 is a schematic sectional view of the organic EL device according to this embodiment.

In FIG. 1, 1 is a back electrode, 2 is an organic light emitting layer, 3 is a transparent electrode, 4 is a light reflecting material, 5 is a light converging structure,
Reference numeral 6 denotes a total reflection suppressing structure, and 7 denotes a support member for supporting the light collecting structure from the outside thereof, which is a light absorbing material in this embodiment. Note that FIG. 1 shows a basic configuration, and the present invention is not limited to this configuration. Organic light emitting layer 2
There is no problem even if a layer such as an electron transporting layer or a hole transporting layer described later is present as a part of or adjacent to the organic light emitting layer 2.

The organic light emitting layer is required to obtain a high quantum yield in a solid state, have a good film-forming property, and have a high carrier transporting property. Examples of the manufacturing method include vacuum heating vapor deposition in the case of a low molecular material, and coating methods such as dip coating and spin coating in the case of a polymer material (polymer material). (For an example of the polymer material, see Electronic Information Display Handbook (Baifukan) p. 407-p. 408.) Also, as an example of a typical organic small molecule light emitting material, tris (8-
Quinolinolato) aluminum complex (Alq3), bis (benzoquinolinolato) beryllium complex (BeBq),
Eu (DBM) 2 (Phen), which is an Eu complex, and DPVBi, which is a distyryl derivative, are shown (see Handbook of Electronic Information Display (Baifukan) p.405), but other materials can be used as an organic light emitting material. There is no problem. Further, a material having a high fluorescence quantum yield is used as a dopant, and is used for modulation of emission color, color mixing, and improvement of emission efficiency. As an example of a typical dopant material, coumarin 6, rubrene, quinacridone,
DCM-1 is shown (see Electronic Information Display Handbook (Baifukan) p.406), but of course,
It does not limit the use of other materials.

Although the substrate is not shown in FIG. 1, the substrate is a base material that supports the organic EL device of FIG. Indium-tin oxide (ITO) is a typical example of what is used as the anode electrode (corresponding to the transparent electrode 3 of the present embodiment) on the substrate, and it can be used as a transparent electrode and can be produced by vacuum deposition or sputtering.

For the cathode (corresponding to the back electrode 1 of this embodiment), magnesium, lithium, sodium, potassium, calcium, magnesium, aluminum, indium, silver, lead, tin, chromium or the like having a small work function are used as a single metal or a plurality of metals. Can be used as an alloy. Also, the cathode is
It may have a single-layer structure or a multi-layer structure.

Although not shown, an electron transport material or a hole transport material which plays a role of injecting electrons and holes in a balanced manner is used. In that case, an electron transport material or a hole transport material is contained in the organic light emitting layer 2,
Alternatively, it may be another layer arranged next to the organic light emitting layer 2. An arylamine derivative is generally used as the electron transport material, and PB is used as a typical electron transport material.
D, TPhen, OXD, TAZ are shown (see Electronic Information Display Handbook (Baifukan) p.407). In addition, as hole transport materials, 1, 2,
4-oxadiazole derivative, 1,3,4-triazole derivative, phenanthroline derivative are used,
Typical hole transport materials include TPD, α-NPD,
TPT and Spiro-TPD were shown (see Electronic Information Display Handbook (Baifukan) p.406). Here, the configuration in which light is extracted from the anode side has been described as an example, but, of course, the configuration in which the light extraction side is the cathode may be used.

The light converging structure 5 has a structure (shape) for reducing the substantial light emitting area. Here, the taper structure is taken as an example. That is, this tapered structure has a structure in which the cross-sectional area of the opening becomes smaller from the organic light emitting layer toward the light extraction direction. For example, a cone shape,
The shape of a quadrangular pyramid, the shape of a polygonal pyramid, or the shape of a truncated cone thereof applies to a structure that substantially reduces the light emitting area, but is not limited to these shapes. In addition, it is preferable that the side surface of the material on the light transmitting side in the tapered structure is formed of a reflecting surface. The reflecting surface is the light reflecting material 4 described above, and the reflecting surface is the light collecting structure 5.
It may be formed on the surface, may be formed on the surface of the light absorbing material 7 which is a supporting member, or may be a surface provided as a separate member provided between the light collecting structure 5 and the light absorbing material 7. May be.

The refractive index of the material of the light collecting structure 5 is equal to or higher than the refractive index of the organic light emitting layer 3. The refractive index of the material of the total reflection structure 6 is equal to or higher than the refractive index of the organic light emitting layer 3.

Further, in the case of the structure like the element shown in FIG. 1, that is, in the structure in which the organic light emitting layer 3 is immediately adjacent to the light collecting structure 5, the refractive index of the organic light emitting layer 3 and the material of the light collecting structure 5 are Although attention is paid to the refractive index (or the refractive index of the organic light emitting layer 3 and the refractive index of the total internal reflection suppressing structure 6), for example, another charge is provided between the organic light emitting layer 3 and the light condensing structure 5. When the transport layer is provided, the organic EL element may be designed by paying attention to the refractive index of at least one of the light collecting structure 5 and the total reflection suppressing structure 6 and the refractive index of the organic light emitting layer 3. The light-emitting layer that constitutes the EL device of the present invention is defined by assuming a device having a structure in which the other charge transport layer exists and a device having a structure in which the other charge transport layer does not exist.

The total reflection suppressing structure 6 has at least the reference numeral 1,
In order to suppress the total internal reflection that occurs at the interface with the medium (for example, air) outside the element composed of 2, 3, 4, 5, 6, and 7, the structure in which the incident angle to the element external medium is made small. Have. For example, a structure having a convex lens shape or a cone shape can be given as an example. In this embodiment, the convex lens structure is shown in FIG. 1, but the cone-shaped structure will be described later.

FIG. 2 is a schematic view showing a state in which a plurality of organic EL elements of this embodiment are arranged, and FIG. 2A is a bird's eye view of an organic EL element having a total reflection suppressing structure 6, and FIG. B) is a schematic view of the same as seen from the total reflection suppressing structure 6 side. As shown in FIG. 2 (B), a plurality of total reflection suppressing structures 6 (convex lenses in this case) are arranged in a matrix. The total internal reflection suppressing structure 6 is arranged on the light absorbing material 7. The solid line circles shown in FIG.
It is an opening in the surface of the light absorbing material 7 shown in FIG. 6B, and is also the opening, that is, the surface on the light emission side of the light converging structure 5. In addition, the dotted line circle shown in FIG. 2B illustrates the contour of the surface where the total internal reflection suppressing structure 6 contacts the surface of the light absorbing material 7. As shown by a dotted circle, a total reflection suppressing structure 6
The surface in contact with the surface of the light-reflecting material 7 is larger than the surface of the light-collecting structure 5 on the light-exiting side, and is large enough to cover the surface of the light-collecting structure on the light-exiting side. The relationship of the sizes is clear from FIG.

In this embodiment, the total internal reflection suppressing structure 6 is used.
The surface in contact with the surface of the light absorbing material 7 may be larger than or the same as the surface of the light converging structure 5 on the light emitting side. If it is larger, the proportion of the emitted light increases from the opening having an angle distribution smaller than the total reflection angle, and as a result, it is possible to effectively suppress the total reflection occurring at the interface between the anti-reflection structure and the air. On the other hand, when the sizes are the same, there is an effect of improving the contrast due to the effect of suppressing the reflected light by the light absorbing material which is the supporting member provided around the opening.

For example, when the total internal reflection suppressing structure 6 is a convex lens structure (shape) and the surface of the total internal reflection suppressing structure 6 in contact with the surface of the light reflecting material 7 is larger than the surface of the light converging structure 5 on the light emitting side, the opening is formed. The light emitted from (the light emission surface of the light converging structure 5) is
At the interface between the total internal reflection and the air, there are many angles that are smaller than the total internal reflection angle, and there is an effect that light can be effectively extracted to the outside of the element. (Shape) and the surface of the total reflection suppressing structure 6 in contact with the surface of the light reflecting material 7 has the same size as the surface of the light converging structure 5 on the light emitting side, the total reflection angle is equal to or less than the total reflection angle due to the conical structure. The ratio of the emitted light having an angular distribution is increased, so that the light can be effectively extracted to the outside of the element, and the contrast is improved by the effect of suppressing the reflected light by the light absorbing material provided around the opening. .

If the tapered light converging structure is not provided, it becomes difficult to control the radiation angle distribution, and the total reflection suppressing effect cannot be sufficiently obtained by the total reflection structure suppressing structure. As a result, It will be difficult to design both front strength and total extraction efficiency. Further, when the refractive index of the material forming the condensing structure and the anti-reflection structure is lower than that of the organic light emitting layer, the radiation angle distribution in the tapered portion is biased to a large angle (when the element is viewed obliquely). It has a radiation distribution that makes it look brighter.

This means that when used as a display device, it looks brighter when observed from an oblique direction than when observed from the front. As a display device, it is preferable that the brightness does not change when observed from any direction. For the above reasons, it is necessary that the tapered light-collecting structure, the light-collecting structure, and the total internal reflection preventing structure are members having a refractive index higher than that of the material forming the organic light-emitting layer.

In the present embodiment, the member for supporting the light collecting structure 5 has been described as a light absorbing member, but the light collecting structure itself does not necessarily have to be a light absorbing member, and it supports the light collecting structure 5, for example. Of the surface of the support member (the light absorbing material 7 of the present embodiment), at least the surface on the side supporting the total reflection condensing structure 6 is provided with another member (light absorbing member) so as to have a light absorbing function, or The surface itself may be surface-treated so as to have a light absorbing function. By devising such light absorption, the light emitting point is surrounded by the light absorbing member in one element.

Since the light absorbing member is generally dark, the contrast is improved within one element, or the contrast is improved because glare due to external light can be prevented.
Even when a plurality of elements are arranged, a high contrast can be maintained for light emitted from each element, or glare due to external light can be prevented, so that the contrast is improved.

Further, in this embodiment, the light converging structure 5 and the total reflection suppressing structure 6 may be arranged separately or integrally. The refractive indices of the light converging structure 5 and the total reflection suppressing structure 6 may be the same value or may be slightly different.

(First Embodiment) A schematic view of an organic EL device according to the first embodiment is shown in FIG. This example has a light condensing structure and a total reflection suppressing structure, like the organic EL device according to the above-described embodiment of the invention. The organic EL device of this example was designed as described below. The element size was 80 μm square, and an organic light emitting layer composed of organic molecules and another organic compound layer (refractive index: n (org) = 1.71) 2 were further formed on the back electrode 1 using metal. IT on
Transparent conductive material such as O (refractive index: n (ITO) = 2.
0) 3 was laminated. Further, the tapered light-collecting structure 5 was provided on the transparent conductive material, and the total reflection suppressing structure 6 was provided on the light-collecting structure 5. The total film thickness of the organic compound layer and other organic compound layers was 100 nm, and the film thickness of ITO was 100 nm.

The material of the light converging structure 5 having the tapered structure is TiO ₂ (refractive index: n (TiO 2) = 2.3).
A light absorbing material 7 is provided around the tapered structure.
A light reflecting material 4 is provided on the boundary surface between the light absorbing material and the tapered structure. As the light absorbing material 7, for example, a black plastic material or the like can be used.
The light reflecting material is a metal material such as gold, silver or aluminum. Then, the light reflecting material which is the metal material may be used as a thin film material prepared by a method such as vapor deposition, sputtering, dipping, or the like, or the light reflecting material may be a high refractive index material and a low refractive index material (for example, T
Alternatively, a dielectric thin film mirror structure manufactured by alternately stacking (iO ₂ and SiO ₂ ) may be used. Further, in this embodiment, the taper structure has a truncated cone shape, and the taper angle α
Was set to α = 25 °, and the height h of the structure was set to h = 30 μm.

Further, the shape of the total reflection suppressing structure is a convex hemispherical lens, and the radius of curvature r is r = 40 μm. The constituent material was TiO ₂ (refractive index: n (TiO ₂ ) = 2.3), and the arrangement was such that the center of the exit opening of the condensing structure was aligned with the optical axis.

The frontal strength and the total extraction strength of the device having the above structure were compared and examined with the device having a conventional structure using a glass substrate. The front intensity is an index of how bright an observer looks at a luminescent organic EL element from the front, and here, the intensity of light emitted in a direction normal to the surface of the organic luminescent layer is used. Radiation intensity, and the total extraction intensity is the total intensity of light emitted from the organic light emitting layer to the outside of the element (in air), and is the integrated value of the emission intensity at all emission angles.

Regarding the frontal intensity, the point at the extension in the direction of the normal to the surface of the organic light emitting layer was used as the observation point, and the radiation intensity at the observation point (far field) sufficiently far from the organic EL element was evaluated. For the total take-out strength,
It was evaluated by the integrated value of the radiation intensity at the observation point in the far field for all radiation angles. The results are shown graphically and shown in FIGS. 4 and 5.

FIG. 4 shows a conventional organic EL device having an organic EL device formed on a glass substrate (referred to as "glass substrate").
And FIG. 5 is a comparative graph of frontal strength in Example 1 according to the present invention, and FIG. 5 is a comparative graph of total extraction strength in a conventional organic EL element and Example 1 according to the present invention. A conventional organic EL element having an organic EL element formed on a glass substrate is an organic EL element having a structure in which a transparent electrode, an organic light emitting layer, and a metal electrode are provided on the glass substrate as shown in FIG.
It is an L element. The vertical axis is the arbitrary intensity. As can be seen from the graph, the front strength is about 1.3 times that of the conventional structure, that is, the organic EL element is formed on the glass substrate, and the total extraction strength is about 2. One time strength was obtained. The angular distribution at this time is shown in FIG. The angular distribution is the distribution of radiation intensity at each radiation angle. azimuth
The radiation intensity (W / sr) is shown in the direction, and the radiation angle is shown in the radial direction. As a result, the front intensity and the total extracted light intensity are improved as compared with the conventional one, and in addition, in FIG. 6, ± 45 ° from the front (corresponding to 180 ° in FIG. 6).
As can be seen from the fact that there is no large deviation in the radiant intensity in a range of about 135 ° to 225 ° in FIG. 6, an organic EL element having a wide viewing angle characteristic without strong directivity is realized. You can

(Second Embodiment) FIG. 7 shows a schematic view of an organic EL device according to the second embodiment. Further, a schematic view of a bird's-eye view and a front view is shown in FIG. This example is the organic EL of Example 1.
Unlike the convex lens structure (shape), the element and the total internal reflection suppressing structure 6 have a conical structure (shape), which is different in structure.

In this embodiment, the conical structure (shape) has the same size as the side surface of the opening of the light converging structure 5 and is provided right above it. The organic EL device of this example was designed as described below. The element size is 80 μm square, and the organic light emitting layer composed of organic molecules and the other organic compound layer 2 (refractive index: n (org)) on the back electrode 1 using metal.
= 1.71), and a transparent conductive material 3 such as ITO (refractive index: n (ITO) = 2.0) was further laminated thereon.

Further, a tapered light-collecting structure 5 was provided on the transparent conductive material, and a total reflection suppressing structure 6 was provided on the light-collecting structure 5. The total thickness of the organic compound layer and other organic compound layers is 100 nm, and the thickness of ITO is 1
It was set to 00 nm. The material forming the taper structure is TiO
₂ (refractive index: n (TiO ₂ ) = 2.3), and the periphery of the tapered structure was made of a light absorbing material. Further, the boundary surface between the light absorbing material and the tapered structure is made of a light reflecting material.
The taper angle α of the tapered structure was α = 25 °, and the height h of the structure was h = 30 μm.

The total reflection suppressing structure has a convex conical shape with a bottom surface radius r of r = 26 μm and a cone taper angle β of β = 50 °. The material is TiO
₂ (refractive index: n (TiO ₂ ) = 2.3), and the arrangement was such that the center of the exit opening of the condensing structure was aligned with the optical axis. The radius of the convex conical bottom surface is 26 μm on the opening side of the condensing structure on the bottom surface.

The frontal strength and the total extraction strength of the element having the above structure were compared and examined with the element having the conventional structure using the glass substrate. FIG. 9 shows a comparison graph of frontal strength, and FIG. 10 shows a comparison graph of total extraction strength. As a result, it was confirmed that the front light intensity and the total extraction light intensity were almost the same and the extraction efficiency was comparable. On the other hand, in the organic EL element of Example 2, the opening area is about 23% of that of the element having the conventional configuration, which means that the total light extraction efficiency changes even if the light emitting area is 23% as compared with the conventional configuration. It indicates that they have not. In addition, since the supporting member other than the opening is made of the light absorbing material, the reflected light component from the back electrode is significantly reduced. As a result, visibility and contrast can be improved.

(Third Embodiment) As a third embodiment, a full-color organic EL display will be described. A schematic view of the cross-sectional shape and a schematic front view are shown in FIG. Substrate 30,
A TFT 31 that drives each pixel. A rear electrode, a red light emitting material layer 33, a green light emitting material layer 34, a blue light emitting material layer 35, a transparent electrode 36, a light condensing structure 5, and a total reflection suppressing structure 6 for each pixel, which are formed on the TFT, are provided.

In the conventional structure, since the light extraction efficiency to the outside of the device is low, it is necessary to flow more current to the organic light emitting layer in order to realize a bright display, which results in power consumption and material life. Was disadvantageous in that. At the same time, it is necessary to increase the degree of integration in order to realize a high-definition display. As the degree of integration increases, the element size decreases, the light emitting area decreases, and the brightness decreases. Therefore, it has been desired that the light emitted from the organic light emitting layer be efficiently extracted to the outside of the device.

In the organic EL display of the present invention, since the structure for suppressing total reflection and the condensing structure are provided, light can be extracted more efficiently than that of the conventional structure. In addition, the total reflection suppressing structure and the light collecting structure are organic EL.
Since it can be provided after the device is formed, it is
It can be provided regardless of the L element structure. As a result, it is possible to realize a full-color organic EL display that achieves high brightness, low power consumption, high visibility, and high color purity.

[0051]

As described above, according to the present invention,
It is possible to provide an EL element that can efficiently extract light to the outside of the element, and to provide an EL display that has improved brightness and reduced power consumption.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross-sectional shape of an organic EL element according to the present invention.

FIG. 2 is a schematic view of a bird's-eye view (A) and a plan view (B) of an organic EL element according to the present invention.

FIG. 3 is a schematic view of a cross-sectional shape of the organic EL element in Example 1.

FIG. 4 is a graph comparing front strengths in Example 1.

FIG. 5 is a graph comparing the total take-out strengths in Example 1.

FIG. 6 is a graph of angular distribution in the far field according to the first embodiment.

FIG. 7 is a schematic view of a cross-sectional shape of the organic EL element in Example 2.

FIG. 8 is a bird's-eye view (A) of the organic EL element in Example 2.
And schematic view of plan view (B)

9 is a graph comparing front strengths in Example 2. FIG.

FIG. 10 is a graph comparing the total take-out strengths in Example 2.

FIG. 11 is a schematic view of a cross-sectional shape view (A) and a plan view (B) of an organic EL element in Example 3.

FIG. 12 is a schematic view of a conventional organic EL device.

FIG. 13 is an explanatory diagram of total reflection that occurs in a conventional organic EL element.

FIG. 14 is a schematic view of an organic EL element having a conventional microlens.

[Explanation of symbols]

1 Back electrode 2 Organic light emitting layer 3 transparent electrodes 4 Light reflecting material 5 Light collecting structure 6 Total reflection suppression structure 7 Support member (light absorbing material) 30 substrates 31 TFT 32 back electrode 33 Organic light emitting material layer of red light emitting pixel 34 Organic light emitting material layer of green light emitting pixel 35 Organic light emitting material layer of blue light emitting pixel 36 Transparent electrode 91 Back electrode 92 Organic light emitting layer 93 Transparent electrode 94 substrates 95 air 96 micro lens

Claims (8)

[Claims] 1. An EL device having a transparent electrode provided on the light extraction surface side and a back electrode provided so as to face the transparent electrode, and comprising a light emitting layer between the transparent electrode and the back electrode. Then, a total reflection suppressing structure is provided on the light extraction surface side, and a light condensing structure for substantially narrowing a light emitting area is provided between the light emitting layer and the total reflection suppressing structure. Of the materials forming the total reflection suppressing structure and the light collecting structure, at least the light collecting structure has a refractive index higher than that of a material forming the light emitting layer.
L element. 2. The EL device according to claim 1, wherein the light-collecting structure has a reflecting surface in the in-plane direction of the device. 3. The taper structure according to claim 1, wherein the light-collecting structure has a taper structure in which an area of a surface on the light emitting side is smaller than an area of a surface of the light-collecting structure on the light emitting layer side. E
L element. 4. The E according to claim 1, wherein the total internal reflection suppressing structure is a convex lens structure or a conical structure.
L element. 5. A light absorbing member is provided around the surface on the light emitting side of the light converging structure.
The EL device according to 1. 6. A material constituting a plurality of the light-collecting structures is arranged in the light-absorbing member, and the light-absorbing member is provided between surfaces of the plurality of light-collecting structures on the light emission side. The EL element according to claim 5, wherein the EL element is arranged. 7. The EL device according to claim 1, wherein the material forming the total reflection suppressing structure and the material forming the light collecting structure are both the same material and have the same refractive index. 8. A display device comprising the EL element according to claim 1.