JP2000077181A - Electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent light from leaking from the wall face of a ramp in a projecting or recessed part, in an EL element to bring down light below a transparent substrate by disposing a luminescent layer placed between a pair of electrodes on projecting parts among projecting and recessed parts formed on the transparent substrate. SOLUTION: Plural striped and transparent electrodes 3 are formed on projecting parts 2b among plural striped projecting and recessed parts 2 formed on one side 1a of a transparent substrate 1, a luminescent layer 4 is formed on one side of the projecting parts 2b and the transparent electrodes 3, and plural striped counter electrodes 5 are formed on the luminescent layer 4. A light reflecting film 6 of aluminum and gold is formed on the wall side 2c of a ramp in each projecting or recessed part 2, and is electrically connected to each transparent electrode 3, while an adjacent light reflecting film 6 is electrically separated by the recessed part 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL element (electroluminescence element) applied to a thin-film display, a lighting device, and the like, and more particularly to an improvement in light extraction efficiency.

[0002]

2. Description of the Related Art Generally, an EL element is composed of an inorganic EL and an organic EL.
L. As shown in FIG.
Generally has, on a transparent substrate such as glass, a light-emitting layer 304 composed of three layers in which an inorganic light-emitting layer 301 mainly composed of zinc sulfide is sandwiched between insulating layers 302 such as silicon oxide. The upper and lower portions are sandwiched between a transparent lower electrode 305 and an upper electrode 306 made of a metal thin film or the like. When a high AC voltage of about 200 V is applied between the electrodes 305 and 306, the inorganic light emitting layer 301 is applied when the voltage is applied.
The electrons emitted from the interface with the insulating layer 302 are accelerated, and excite the dopant atoms in the inorganic light emitting layer 301 to emit light.

Further, as shown in FIG.
L is a light emitting layer (thin film) 401 containing a fluorescent organic compound,
It has a structure sandwiched between an anode 402 and a cathode 403. Then, a DC voltage of about 10 V is applied to both poles 402 and 403, and electrons and holes are injected into the thin film 401 to be recombined, thereby generating excitons and generating light when the excitons are deactivated. Utilizing the emission of light leads to light emission.

Conventionally, in these thin-film display devices, light leakage from the end face of a transparent substrate such as glass has been large, and the display brightness on the lower surface of the substrate, which is the viewing direction, has been reduced. And
At this time, the light extraction efficiency is generally about 20%. Therefore, there is a problem that the input power becomes high in order to obtain the required luminance, and this high input power causes not only an energy problem but also an increase in the load on the element,
Decrease reliability.

Here, FIG. 5 shows a state of the light leakage when an inorganic EL is taken as an example. In the flat transparent substrate K1, light incident on the substrate lower surface K1a at a low angle, such as the optical path 102, depends on the difference in refractive index between air and the substrate K1.
The light is totally reflected at the interface between the substrate K1 and the air and leaks from the side surface of the substrate K1 (indicated by a broken arrow in FIG. 5). The condition of total reflection at this time is determined as the critical angle α from the difference in refractive index. Therefore, of the light from the light emitting layer, light incident at an angle equal to or more than this angle α leaks to the side surface of the substrate.

For the purpose of improving the efficiency of extracting light to the outside, a device in which irregularities are formed on the substrate of the device (Japanese Patent Laid-Open No.
86587, JP-A-3-46791). These are for efficiently extracting the reflected light between the light emitting layer having a significantly different refractive index and the lower insulating layer to the lower part of the substrate in the inorganic EL.

[0007]

However, as a result of the present inventors' trial production and examination of a substrate on which uneven portions are formed based on the above-mentioned prior art, a light emitting layer material and a lower insulating layer having greatly different refractive indices were obtained. Although it was possible to efficiently extract the reflected light between the two and reduce the leakage of light, it was found that light leaked out of the viewing direction from the stepped wall surface of the uneven portion on the substrate. FIG. 6 shows this state.

FIG. 6 shows a prototype of the present inventors, in which an uneven portion 2 is provided on a substrate 1, a transparent lower electrode (transparent electrode) 3 is provided on the convex portion 2b, and a light emitting layer 4 is provided thereon. And an upper electrode (counter electrode) 5 is laminated thereon. In this EL device, the slope of the uneven portion 2, that is, the step portion wall surface 2c
If the incident angle γ of light to the optical path is equal to or larger than the critical angle α, the optical path 10
As shown in FIG. 3, total reflection occurs on the step wall surface 2c of the uneven portion 2, and light can be extracted in the viewing direction.

Therefore, the amount of light incident on the lower surface 1b of the substrate 1 so as to be out of the viewing direction is reduced, and it is difficult for the light to leak from the side surface of the substrate 12. However, even in this structure, since there is light in the optical path (the optical path 102 shown by a broken arrow in FIG. 6) in which the incident angle γ of the light on the step wall 2c is equal to or smaller than the critical angle α, this light is 2c, which also causes a problem of a decrease in display luminance.

In view of the above problems, the present invention arranges a light emitting layer sandwiched between a pair of electrodes on a convex portion of a concave and convex portion formed on a transparent substrate, and extracts light below the transparent substrate. In an EL element, an object is to prevent light from leaking from a step portion wall surface of an uneven portion.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, the transparent substrate (1) covers one surface (1).
a) A transparent first electrode (3), a light-emitting layer (4), and a second electrode (5) are sequentially stacked on top of each other, and light from the light-emitting layer (4) is applied to the other surface (1b) of the transparent substrate (1). E) to take out to the side
In the L element, an uneven portion (2) is formed on one surface (1a) of the transparent substrate (1), a first electrode (3) is formed on the convex portion (2b), and at least a step of the uneven portion (2) is formed. The light reflecting film (6) is formed on the wall surface (2c).

As a result, the light traveling downward from the light emitting layer (4) to below the first electrode (3) is totally reflected by the light reflecting film (6) formed on the step wall surface (2c) of the uneven portion (2). I do. Therefore, light emitted by electroluminescence can be efficiently extracted in the viewing direction from the other surface (1b) of the transparent substrate (1) on the light extraction side, and leakage of light from the step wall surface (2c) can be prevented. .

Therefore, the efficiency of extracting light to the lower surface of the substrate can be improved, and as a result, a high luminance EL element or a reduction in input power for obtaining the same luminance can be realized. Here, the light emitting layer (4) has at least one light emitting layer composed of an organic compound (organic EL) or has a light emitting layer composed of an inorganic substance (inorganic EL).
Either may be used.

However, in particular, the present invention can improve the efficiency of extracting the light transmitted through the first electrode (3) below the light emitting layer (4), and therefore the first electrode (3 ) And the light emitting layer (4) have a high effect of improving the light extraction efficiency in the organic EL having a similar refractive index. Further, the light reflecting film (6) is preferably made of a metal material so as to reflect visible light. Specifically, a metal material such as aluminum, gold, silver, copper, and magnesium can be employed.

According to a third aspect of the present invention, in each of the plurality of concave and convex portions (2), the first electrode (3) is formed on the convex portion (2b) and is made of metal. In which the light reflection film (6) is formed on the step wall surface (2c). In such a multi-electrode EL device, in the invention according to claim 3, the adjacent first electrode (3) and the light reflecting film (6) are electrically connected and the adjacent light reflecting film (6) is electrically connected. ) Is electrically separated by the concave portion (2a).

To electrically divide the light reflecting film (6) at the concave portion (2a) means, specifically, to form the light reflecting film (6) only on the step portion wall surface (2c) and to form the concave portion (2a). This is achieved by not forming on the bottom surface. Thereby, in addition to the effect of the first aspect, insulation between the adjacent first electrodes (3) is ensured. Therefore, for example, a matrix-type EL in which the first and second electrodes (3, 5) form a matrix
An EL element which can be partially displayed, such as an element, can be provided. Further, the first electrode (3) is a light reflection film (6) made of metal.
And the first electrode (3) can be reduced in resistance by using the light reflecting film (6) as an auxiliary electrode.

Further, in the invention described in claim 4, in the multi-electrode type EL device, a metal light reflecting film (6) is formed on the entire surface of the concave portion (2a) including the step portion wall surface (2c), It is characterized in that the adjacent first electrode (3) and the light reflecting film (6) are electrically connected, and all the adjacent first electrodes (3) are connected to each other via the light reflecting film (6). In contrast to the third aspect of the present invention, a full-display E
An L element can be provided.

Here, as in the invention described in claim 5 or claim 6, the uneven portion (2) may be formed on the transparent substrate (1) itself, or may be formed on one surface of the transparent substrate (1). 1a) The film member (8) formed so as to protrude upward is formed as a convex portion (2b), and the non-formed portion of the film member (8) on one surface (1a) of the transparent substrate (1) is formed as a concave portion (2a). It may be done.

The symbols in parentheses above are examples showing the correspondence with specific means described in the embodiments described later.

[0020]

(First Embodiment) An EL device 100 according to a first embodiment of the present invention is shown in an explanatory view of FIG. In this embodiment, an EL element having matrix display pixels is used. 1A shows a partially cutaway plane of the EL element 100, FIG. 1B shows an AA cross section of FIG. 1A, and FIG. 1C shows an enlarged configuration of a portion B in FIG. FIG.
In the drawings including (a) below, the drawings showing the planar configuration are also hatched, but are shown for convenience and are not cross-sections.

The substrate (transparent substrate) 1 is a transparent substrate made of a transparent insulating material such as glass, and has a plurality of uneven portions 2 on one surface 1a. In the present example, the concave and convex portion 2 is formed by forming a concave portion 2a by shaving one surface 1a of the substrate 1, and forming a non-sharpened portion as a convex portion 2b. FIG.
As shown in (a) and (b), the concave portion 2a and the convex portion 2b are formed in a plane stripe shape.

A plurality of transparent electrodes (first electrode) made of indium-tin oxide (ITO) or the like, which is a transparent electrode material, are formed on each convex portion 2b on the surface 1a on which the plurality of uneven portions 2 are formed. 3) are formed in a plane stripe shape corresponding to the projections 2b. The light emitting layer 4 is formed over the entire surface of each of the recesses 2a and each of the transparent electrodes 3 using the material used for the inorganic EL or the organic EL as described above.

Here, in the case of the inorganic EL type, as described in FIG. 14A, the light emitting layer 4 of the present invention is formed by insulating the inorganic light emitting layer mainly composed of zinc sulfide or the like with silicon oxide or the like. It consists of three layers sandwiched between layers, while organic E
In the L type, as described in FIG. 14B, a plurality of light emitting layers containing a fluorescent organic compound (for example, 2 to 5) are used.
Layer) It consists of a laminated film laminated.

Here, as the fluorescent organic compound, for example, known α-NPD (α-naphthylphenylbenzene), TPD (tetraphenyldiamine), ALQ (quinolinol aluminum complex), BALQ (bis (2-methyl-8) -Quinolinolate) (2,3-dimethylphenolate) aluminum), PVK (polyvinyl carbazole), and the like.

A plurality of counter electrodes (second electrodes) 5 are formed on the light emitting layer 4. The counter electrode 5 has a planar stripe shape, and the stripe is a transparent electrode 3.
(See FIG. 1 (a)). These counter electrodes 5 may be transparent,
Usually, an electrode material that does not transmit light is used, and for the inorganic EL, for example, aluminum or the like, and for the organic EL, for example, lithium fluoride, aluminum, or an alloy of magnesium and silver can be used.

Here, in each of the concavo-convex portions 2, a step portion wall surface 2c constituted by a convex portion 2b on which the transparent electrode 3 is formed and an adjacent concave portion 2a has aluminum, silver,
A light reflection film 6 made of a metal material such as gold is formed. The light reflecting film 6 totally reflects light traveling from the light emitting layer 4 to below the first electrode 3.

The light reflecting film 6 is formed almost only on the stepped wall surface 2c, not on the concave portion 2a.
Adjacent light reflection films 6 are electrically disconnected from each other. Then, as shown in FIG. 1C, each of the concavo-convex portions 2 is electrically connected to the adjacent transparent electrode 3 so as to be conductive. Therefore, since the transparent electrodes 3 are insulated from each other, a matrix type EL element having pixels orthogonal to the electrodes 3 and 5 is formed.

In the EL element 100 having such a configuration, a voltage is applied to each of the electrodes 3 and 5 by a driving circuit (not shown), so that the light emitting layer 4 emits light at a portion (pixel) orthogonal to the electrodes 3 and 5. . This light is extracted from the transparent electrode 3 and the substrate 1 to the other surface 1b of the substrate 1, that is, the lower surface of the substrate. Here, since the light reflection film 6 is made of metal, it functions as an auxiliary electrode and contributes to lowering the resistance of the conductive transparent electrode 3.

Next, a method for manufacturing the EL element 100 of the present embodiment will be described. One example of the manufacturing method is shown in FIGS.
(F) and FIGS. 3 (a) and 3 (b). First, a transparent flat substrate K1 made of glass or the like is prepared (FIG. 2).
(A)), the unevenness is formed on one surface of the planar substrate K1 by a physical method such as machining or a chemical method using a chemical solution, and the substrate 1 having the unevenness portion 2 is manufactured (FIG. 2).
(B)).

As a physical method of forming the concavities and convexities, first, a photosensitive resin is applied on the entire surface of the flat substrate K1, and then the photosensitive resin in a portion where the convex portion 2b is to be formed is left by a photo process using a photomask. Thereafter, the substrate K1 is shaved by sandblasting or ion irradiation to obtain the concave portion 2a, and then the photosensitive resin is peeled off to obtain the substrate 1 having the uneven portion 2.

Also, without using a photosensitive resin, the recess 2
a metal mask having an opening corresponding to a.
The substrate 1 having the concave-convex portions 2 can be obtained by arranging it immediately above and performing sandblasting or ion irradiation from above. Further, as a chemical method of forming the unevenness, first, a photosensitive resin is applied on the entire surface of the planar substrate K1, and then a photosensitive process using a photomask leaves a portion of the photosensitive resin in which the convex portion 2b is to be formed. Thereafter, the substrate K1 is etched using a chemical corresponding to the substrate K1, for example, hydrofluoric acid in the case of a glass substrate. After obtaining the concave portion 2a, the photosensitive resin is peeled off to obtain the substrate 1 having the concave and convex portion 2.

Next, as shown in FIG. 2C, a light reflecting film 6 is formed on the entire surface of the substrate 1 by a sputtering method, a vapor deposition method or the like. Then, the photosensitive resin is applied on the entire surface, and then the photosensitive resin is left on the step wall surface 2c of the uneven portion 2 by a photo process. Thereafter, the light reflecting film 6 is etched using an etching solution (FIG. 2D). For example, when aluminum is used for the light reflection film 6, potassium hydroxide, hot phosphoric acid, or the like is used as an etchant.

Then, the photosensitive resin is removed to obtain the substrate 1 on which the light reflecting film 6 is formed on the step surface 2c. next,
Then, as shown in FIG. 2E, a transparent electrode 3 is formed over the entire surface by a sputtering method, an evaporation method, or the like. Then, FIG.
As shown in (f), the transparent electrode 3 is patterned, and the transparent electrode 3 on the protrusion 2b and the light reflection film 6 on the step wall 2c are formed.
Is obtained.

Subsequently, as shown in FIG. 3A, a light emitting layer 4 is formed on the entire surface. In the case of an inorganic EL, three layers are sequentially formed by a sputtering method, a vapor deposition method, or the like on an insulating layer such as silicon oxide, an inorganic light emitting layer mainly containing zinc sulfide or the like, and an insulating layer such as silicon oxide. In the case of an organic EL, a film is formed by a vacuum evaporation method, a spin coating method, or the like.

Thereafter, a counter electrode 5 is formed thereon by forming a film by a sputtering method, a vapor deposition method or the like and patterning by a photo process (FIG. 3).
(B)). Thus, the EL element 100 shown in FIG. 1 is completed. Further, the EL element 100 can also be manufactured by the method described below. FIGS. 4A to 4E show EL.
FIG. 9 is a diagram illustrating another example of the method for manufacturing the element 100.

First, a transparent electrode 3 is formed on the entire surface of the flat substrate K1 (FIG. 4A), and a photosensitive resin is applied on the entire surface, and then the projections 2b are formed by a photo process using a photomask K2. The photosensitive resin is left in the portion for forming
(B)). Thereafter, the substrate K1 and the transparent electrode 3 are shaved by sand blasting or ion irradiation to obtain the concave portion 2a, and then the photosensitive resin is peeled off to form the concave and convex portion 2 and the convex portion 2b.
A substrate 1 having a transparent electrode 3 formed thereon is obtained (FIG. 4).
(C)).

It is to be noted that the concave portion 2 can be formed without using a photosensitive resin.
a metal mask having an opening corresponding to a
It is also possible to obtain the same substrate 1 by arranging it immediately above and performing sandblasting or ion irradiation from above. Next, a light reflecting film 6 is formed on the entire surface (FIG. 4).
(D)) After the entire surface of the photosensitive resin is coated thereon, the photosensitive resin is left on the step wall surface 2c of the uneven portion 2 by a photo process.

Thereafter, the light reflecting film 6 is etched using an etching solution.
Is etched (FIG. 4E). When the photosensitive resin is removed, the photosensitive resin is formed on the stepped wall surface 2c, and the convex portion 2b is formed.
The substrate 1 having the light reflection film 6 electrically connected to the transparent electrode 3 is obtained. Subsequently, the light emitting layer 4 and the counter electrode 5 are formed thereon similarly to FIG. 3, whereby the EL element 100 shown in FIG. 1 is obtained.

The other example shown in FIG. 4 has an advantage over the examples shown in FIGS. 2 and 3 in that the unevenness of the substrate and the patterning of the transparent electrode can be simultaneously performed.
That is, the process can be simplified and the cost can be reduced.
Next, the operation of improving the light extraction efficiency in the present embodiment will be described with reference to FIGS. 5 and 6 and FIG. 7 which is an explanatory diagram of the light extraction operation of the present embodiment. In addition,
As described above, FIG. 5 shows an example of the conventional inorganic EL shown in FIG. 14A. FIG. 6 shows a prototype of the present inventors. In FIG. 6, the same portions as those of the EL element 100 of FIG. 1 are denoted by the same reference numerals.

In a conventional flat substrate (usually made of glass) K1 as shown in FIG.
Light incident on the lower surface K1a at a low angle is air (refractive index:
Due to the difference in the refractive index between 1) and glass (refractive index: 1.5 to 1.65), the light is totally reflected at the interface between the substrate K1 and the air and leaks from the side surface of the substrate K1 as indicated by the dashed arrow (light path). 10
2).

The condition for total reflection at this time is determined as a critical angle α from the difference in refractive index. Here, sinα =
There is a relationship of (refractive index of the material on the output side / refractive index of the material on the incident side). When glass having a refractive index of 1.5 is used for the substrate K1, the critical angle α is 42 °. Therefore, the light emitting layer 304
Out of the light from the substrate K1
Leaks to the sides.

On the other hand, in the EL device having the structure in which the unevenness 2 is provided on the substrate 1 as shown in FIG.
If the light incidence γ on the stepped portion wall surface 2c is equal to or larger than the critical angle α, total reflection occurs on the stepped portion wall surface 2c as in the optical path 103, and light can be extracted in the viewing direction. Therefore, as shown in the optical path 102 in FIG. 5, the amount of light incident on the lower surface 1b of the substrate 1 outside the viewing direction is reduced, and it is difficult for the light to leak from the side surface of the substrate 1. However, also in this structure, the incident angle γ of the light on the stepped portion wall surface 2c is the light in the optical path whose angle is equal to or less than the critical angle α, that is, as shown in FIG. There is light like 102.

On the other hand, the EL element 1 of the present embodiment
No. 00, the light reflecting film 6 is formed on the step wall surface 2c of the uneven portion 2 which is a leakage path, so that all light is totally reflected by the light reflecting film 6 irrespective of the angle of incidence on the step wall surface 2c. You. Therefore, there is no light in the optical path 102 leaking from the stepped wall surface 2c as shown in FIG. 6, and it becomes a reflected light path 103 on the stepped wall surface 2c as shown in FIG.

As described above, in the present embodiment, light emission by electroluminescence can be efficiently extracted in the viewing direction from the other surface (substrate lower surface) 1b of the substrate 1, which is the light extraction side, and the light from the stepped portion wall surface 2c can be obtained. Leakage can be prevented. Incidentally, according to the study by the present inventors, the EL element 1
In No. 00, the light extraction efficiency to the lower surface of the substrate could be improved as compared with the conventional one.

Here, the height of the projection 2b, that is, the size of the step is not particularly limited, but is preferably about 0.1 μm to 1 mm. FIG. 8 is a diagram showing each example of the shape of the step portion of the uneven portion 2. The step portion is not limited to a linear shape (FIG. 8A), but may be formed as shown in FIGS. 8B and 8C. The shape as shown may be sufficient. The angle β of the step is preferably about 30 ° to 90 °. Here, the step angle β is obtained by shaping the step with a dicing saw with a taper, or performing small groove processing, and then expanding the groove by etching or ion irradiation to form the concave portion 2a. A range step angle β is obtained.

By the way, according to the present embodiment, the efficiency of extracting light to the lower surface 1b of the substrate 1 can be improved, and as a result, an EL element having a high luminance or an applied power for obtaining the same luminance can be obtained. A reduction can be realized. In particular, according to the present embodiment, the efficiency of extracting light transmitted through the transparent electrode 3 below the light emitting layer 4 can be improved, so that the organic EL having a refractive index closer to the transparent electrode 3 and the light emitting layer 4 than the inorganic EL.
(For example, the refractive index of the organic layer is about 1.6 and is close to that of ITO or glass.) The effect of improving the light extraction efficiency is high.

Further, according to the present embodiment, the light reflecting film 6 is formed almost only on the step portion wall surface 2c and not formed on the bottom surface of the concave portion 2a, so that the light reflecting film 6 is electrically divided by the concave portion 2a. Therefore, insulation between adjacent transparent electrodes 3 is ensured. Therefore, as in the present embodiment, an EL element that can partially display a matrix EL element can be provided. Further, since the transparent electrode 3 is electrically connected to the light reflecting film 6 made of metal, the resistance can be reduced by using the light reflecting film 6 as an auxiliary electrode.

Further, by using the light reflecting film 6 as an auxiliary electrode, it is possible to reduce luminance unevenness due to a voltage effect due to the low conductivity of the transparent electrode 3. For example, organic E
In the case of the L element, the maximum size of a display in which luminance unevenness is not noticeable without using an auxiliary electrode is said to be a few inches on a diagonal. According to the study by the present inventors, it is possible to realize a large screen of 10 inches or more when the metal light reflection film 6 is used as an auxiliary electrode.

Further, since the light reflecting film 6 is made of a metal film having higher heat conductivity than glass or a transparent electrode, it is possible to efficiently transmit heat generated at the time of light emission of the EL element. It is possible to prevent excessive element deterioration. As a result, a longer life of the element can be achieved. (Second Embodiment) The present embodiment relates to a full-display EL element, and is a modification of the first embodiment. FIG. 9 shows an EL element according to this embodiment. In FIG. 9, (a)
Is a plan view of an EL element 200 as a first example of the present embodiment, and (b) is an EL element 3 as a second example of the present embodiment.
00C, (c) is AA of (a) and (b)
Sectional drawing, (d) is a modification of the AA section of (c).
9A and 9C, the light emitting layer 4 and the counter electrode 5 are omitted.

As shown in FIGS. 9A and 9B, the EL element 200 is different from the EL element 100 shown in FIG.
The difference is that the metal light reflecting film 6 is formed on the entire surface of the concave portion 2a including the step portion wall surface 2c, and the adjacent transparent electrode 3 and the light reflecting film 6 are electrically connected. this is,
It can be manufactured by changing the patterning shape of the light reflection film 6.

The EL element 300 shown in FIGS. 9C and 9D is the same as the EL element 20 shown in FIGS. 9A and 9B.
0, the shape and arrangement of the transparent electrode 3 were changed. In the EL element 300, since the projections 2 b and the transparent electrodes 3 are arranged in a substantially circular shape in a plane and in a zigzag pattern, the entire periphery of each transparent electrode 3 is covered with the light reflection film 6. Therefore, in all directions, there is no optical path 102 leaking from the stepped portion wall surface 2c as shown in FIG. 6, and the light extraction efficiency is improved most.

Further, since the projections 2b and the transparent electrodes 3 are circular in a plane, they are arranged in a substantially zigzag pattern as shown in FIG.
The transparent electrodes 3 can be arranged in the finest arrangement (closest filling) in the plane of the substrate 1. Therefore, the ratio of the transparent electrode 3 per unit area of the substrate 1 can be increased, and an EL element having a high aperture ratio and high luminance over the entire surface can be realized.

Here, in the both EL elements 200 and 300, the AA cross section is not limited to the case where the entire concave portion 2a is simply filled with the light reflecting film 6 as shown in FIG. 9 (d). FIG. 9D
Has a structure in which an insulating layer 7 is arranged so as to fill a concave portion above the light reflection film 6. Here, the formation of the light reflecting film 6 in the concave portion 2a is performed by a normal film forming method.

However, usually, the film forming rate is constant in the film forming surface, and therefore the film thickness is also uniform. Therefore, if there is unevenness on one surface 1a of the substrate 1 which is the film forming surface, the unevenness is reduced. The light reflection film 6 is formed in the inherited form. Therefore, in the concave portion 2a, a concave portion is easily formed above the light reflection film 6. In such a case, by adopting the structure of FIG. 9D, the smoothness of the substrate at the time of forming the transparent electrode can be improved, and the transparent electrode can be formed stably.

As described above, the present embodiment has mainly been described with respect to portions different from the first embodiment. According to the present embodiment, the metal light reflection film 6 is provided on the step portion wall surface 2.
c formed on the entire surface of the concave portion 2a including the first electrode 3
And the light reflection film 6 are electrically connected, and as a result, all the transparent electrodes 3 are electrically connected. Therefore, contrary to the first embodiment, a full-display EL device can be provided. In other respects, the same operation and effect as in the first embodiment can be obtained.

(Third Embodiment) This third embodiment is shown in FIG.
Shown in As shown in FIG. 10, the EL element 40 of the present embodiment
Reference numeral 0 denotes a modification of the first embodiment, in which the uneven portion 2 of the substrate 1 is formed by projecting on one surface 1a of the substrate 1 instead of shaving the substrate itself, and the film member 8 is formed as a convex portion 2b. The non-formed portion of the film member 8 in the surface 1a of the substrate 1 is
What is different from the first embodiment is that it is configured as a.

Here, in FIG. 10, the light emitting layer 4 and the counter electrode 5 formed on the concave portion 2a and the transparent electrode 3 in the EL element 400 are omitted. The film member 8 forming the convex portion 2b is a transparent member made of an insulator or the like made of a different material from the substrate 1, and may be a single layer or a multi-layer, or may have a laminated structure composed of a color filter and an overcoat layer such as SiO _2. . That is, by adopting this structure, it becomes possible to apply to multi-coloring or the like.

Next, the manufacturing method of this embodiment will be described with reference to FIGS. First, the film member 8 is formed on the entire surface 1a of the substrate 1 by a known film forming method such as a sputtering method, an evaporation method, and a spin coating method (FIG. 11A). Next, a mask K3 having an opening at a portion where the concave portion 2a is formed is formed thereon using a resist or the like (FIG. 11B).

Then, the film member 8 at the opening of the mask K3 is removed by a physical or chemical method such as sandblasting or ion irradiation, or etching using an etching solution, and the mask K3 is peeled off (FIG. 11).
(C)). Thus, the uneven portion 2 having the remaining film member 8 as the convex portion 2b and the removed portion as the concave portion 2a is formed on the one surface 1a of the substrate 1.
Formed.

After that, similarly to the first embodiment, the transparent electrode 3 is formed by patterning, and the light emitting layer 4 and the counter electrode 5 are formed thereon, whereby the EL element 400 is manufactured. And in this embodiment, the side surface of the membrane member 8 is
The light reflecting film 6 is formed on the stepped portion wall surface 2c, and the same effect as that of the first embodiment is obtained.

(Fourth Embodiment) This embodiment is shown in FIG. The EL element 500 of the present embodiment is a modification of the above-described first embodiment, and has a structure in which an insulator 9 is arranged in each recess 2a in the EL element 100 shown in FIG.
Here, in FIG. 12, the light emitting layer 4 and the counter electrode 5 formed on the transparent electrode 3 and the insulator 9 in the EL element 500 are omitted.

With such a structure, the same operation and effect as those of the first embodiment can be obtained, and the transparent electrode 3 can be formed.
By eliminating the charge concentration points due to the sharp shape of the end, it is possible to prevent electrical leakage at the end of the transparent electrode 3 when the EL element is driven for a long time. (Fifth Embodiment) This embodiment is shown in FIG. The EL element 600 of the present embodiment is a modification of the above-described second embodiment, and is obtained by adding antireflection films 10 and 11 to the EL element 200 or 300 shown in FIG. 9C. Here, also in FIG. 13, the light emitting layer 4 and the counter electrode 5 formed on the light reflection film 6 and the transparent electrode 3 are omitted.

In FIG. 13A, the EL element 200 or 3
00, an anti-reflection film 10
In FIG. 13B, an antireflection film 11 is provided between the projection 2 b and the transparent electrode 3. Here, the anti-reflection films 10 and 11 are thin films made of a material having a filter effect of absorbing a predetermined visible light.
Conversely, light incident from the outside, that is, from the viewing direction, is prevented from being reflected by the antireflection film.

(Other Embodiments) The cross-sectional shape and planar shape of the concave and convex portions are not limited to those in the above-described embodiment, and the design can be changed as appropriate. Further, the above embodiments may be used in combination other than the above, if possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an EL device according to a first embodiment of the present invention.

FIG. 2 is a view illustrating an example of a manufacturing process of the EL element according to the first embodiment.

FIG. 3 is a view showing a manufacturing process following FIG. 2;

FIG. 4 is a view showing another example of the manufacturing process of the EL element according to the first embodiment.

FIG. 5 is an explanatory diagram of a light extraction function in a conventional EL element.

FIG. 6 is an explanatory diagram of a light extraction effect in a prototype of the present inventors.

FIG. 7 is an explanatory diagram of a light extraction action of the present invention.

FIG. 8 is a diagram showing each example of the shape of a step portion in the uneven portion of the present invention.

FIG. 9 is an explanatory view showing an EL element according to a second embodiment of the present invention.

FIG. 10 is an explanatory diagram showing an EL element according to a third embodiment of the present invention.

FIG. 11 is a view showing a manufacturing process of the EL element according to the third embodiment.

FIG. 12 is an explanatory diagram showing an EL device according to a fourth embodiment of the present invention.

FIG. 13 is an explanatory view showing an EL element according to a fifth embodiment of the present invention.

FIG. 14 is a diagram showing a conventional EL element structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... board | substrate, 1a ... one surface of a board, 1b ... other surface of a board, 2 ...
Uneven portion, 2a ... concave portion, 2b ... convex portion, 2c ... step portion wall surface,
Reference numeral 3 represents a transparent electrode, 4 represents a light-emitting layer, 5 represents a counter electrode, 6 represents a light reflection film, and 8 represents a film member.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junji Kido 9-4, Mami-Kita, Koryo-cho, Kitakatsuragi-gun, Nara 3 (72) Inventor Takeshi Ishikawa 1-1-1, Showa-cho, Kariya-shi, Aichi F F within DENSO Corporation Terms (reference) 3K007 AB00 AB02 AB03 AB05 BA06 BB06 CA00 CA01 CB01 DA00 DA02 DA05 DB02 EB00 EB01 FA00 FA01

Claims (6)

[Claims] A transparent substrate (1) and the transparent substrate (1)
Transparent first electrode (3) formed on one surface (1a)
And a light emitting layer (4) formed on the first electrode (3)
And a second electrode (5) formed on the light emitting layer (4), so that light from the light emitting layer (4) is extracted to the other surface (1b) of the transparent substrate (1). In the EL device, the concave and convex portions (2) are formed on the one surface (1a) of the transparent substrate (1), and the first electrode (3) is a convex portion (2) of the concave and convex portions (2).
b) formed on at least a step wall surface (2c) of the uneven portion (2);
EL having a light reflecting film (6) formed thereon
element. 2. The EL device according to claim 1, wherein the light reflection film is made of a metal material. 3. A plurality of uneven portions (2) are formed, and in each of the plurality of uneven portions (2), the first electrode (3) is formed on the convex portion (2); The light reflecting film (6) is formed on the step wall surface (2c), and the adjacent first electrode (3) and the light reflecting film (6) are electrically connected to each other and are adjacent to each other. The EL device according to claim 2, wherein the light reflecting film (6) is electrically separated by the concave portion (2a). 4. A plurality of uneven portions (2) are formed, and in each of the plurality of uneven portions (2), the first electrode (3) is formed on the convex portion (2b); The light reflecting film (6) is formed on the entire surface of the concave portion (2a) including the step portion wall surface (2c), and the adjacent first electrode (3) and light reflecting film (6) 3. The EL element according to claim 2, wherein the element is electrically conducted. 5. The transparent substrate (1) wherein the uneven portion (2) is provided on the transparent substrate (1).
The EL device according to claim 1, wherein the EL device is formed on itself. 6. The transparent substrate (1) wherein the film member (8) formed on the one surface (1a) of the transparent substrate (1) is formed as the projection (2b). 1)
6. The EL device according to claim 1, wherein a non-formed portion of the film member (8) in the one surface (1a) is configured as the concave portion (2a).