JP4185295B2 - Light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light-emitting device used for a backlight for a display such as a liquid crystal display, an illumination such as a room illumination, or a display such as a television.
[0002]
[Prior art]
In recent years, many research reports have been made on organic light-emitting devices using organic materials as light-emitting materials. For example, Applied Physics Letters, Vol. 51, page 913, 1987. Organic light-emitting devices have a feature of surface emission, and recently, high-efficiency organic light-emitting devices exceeding 40 lm / W have recently been reported. For example, the 2000 Annual Meeting of the Japan Society of Applied Physics (31a-H-3). Based on these studies, expectations for lighting devices and displays using surface light emitters that have not existed before are increasing.
[0003]
Conventional light sources are in the form of a bulb or rod, such as a light bulb using a filament and a lamp using a discharge phenomenon, so when used as a lighting fixture, a reflector that mainly reflects light emitted upward and sends it downward. Can be classified into two types: direct illumination provided with a light source and indirect illumination provided with a reflecting plate to diffuse light and reduce glare. On the other hand, an electroluminescence (EL) panel has a feature of surface emission, and by using this, development as new illumination and application as a light source for display are expected.
[0004]
[Problems to be solved by the invention]
An EL panel can be roughly classified into an inorganic EL element and an organic EL element. The characteristic of the organic EL element is that it can be driven at a lower voltage than the inorganic EL element and emits light with high efficiency. Moreover, when compared with a light emitting diode (LED), the efficiency is not inferior, and the fabrication is simple, and therefore, it is expected as a future light source.
[0005]
However, the organic EL element has a drawback that it has a short lifetime in high luminance applications. This is because it is inferior to a fluorescent lamp that emits light with high efficiency of 80 lm / W or more in terms of efficiency, and in high luminance applications, it is inevitably used in a more loaded state.
[0006]
As described above, when the organic EL element is used in the conventional planar structure, there is a problem that the light source that can withstand high-luminance use has a short lifetime.
[0007]
On the other hand, in order to increase the luminous flux obtained from the light emitting surface of the organic EL element, a method of increasing the surface area can be taken. Further, when the surface area of the organic EL element is increased, the light extraction efficiency is improved. In order to increase the surface area, for example, there is a method of forming the surface of the substrate 71 with unevenness as in the light emitting element 70 shown in FIG. A layer 73 and a cathode 74 are formed. In addition, as shown in FIG. 8, there is also a method of forming a laminated light emitting device 80 by laminating light emitting devices 81, 82, and 83 that are planar or uneven.
[0008]
However, these conventional methods have a problem that the surface area of the organic EL element is only about 2 to 3 times that of the conventional method, and the surface area cannot be dramatically increased.
[0009]
The present invention has been made to solve the above-described conventional problems, and by dramatically increasing the surface area of the light emitting element, the amount of current per unit area is reduced, and the light source has a long life even in high luminance applications. The purpose is to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a light-emitting device of the present invention is a light-emitting device in which a plurality of light-emitting elements each including a pair of electrodes and a light-emitting layer disposed between the electrodes are disposed on a substrate, The light emitting surface of the light emitting element is located in a rising direction with respect to the base material.
[0011]
In the light-emitting device of the present invention, the light-emitting element can be formed in a strip shape.
[0012]
In the light emitting device of the present invention, the light emitting element can be formed in a strip shape.
[0013]
In the light-emitting device of the present invention, the light-emitting element can be formed in a cylindrical shape or a column shape.
[0014]
In the light emitting device of the present invention, the light emitting element can be formed in a porous shape.
[0015]
In addition, the light emitting device of the present invention can use a stacked light emitting element in which a plurality of light emitting elements are stacked.
[0016]
In the light emitting device of the present invention, the light emitting layer of the light emitting element may be formed of an organic material.
[0017]
In the light-emitting device of the present invention, the light-emitting layer of the light-emitting element may include a plurality of organic materials having different emission colors.
[0018]
In the light emitting device of the present invention, the organic material may be dispersed.
[0019]
In the light emitting device of the present invention, the organic material may be arranged in an island shape for each emission color.
[0020]
In the light emitting device of the present invention, the light emitting layer of the light emitting element may be composed of a plurality of layers, and each layer may be a layer made of an organic material having different emission colors.
[0021]
In the light emitting device of the present invention, a hole transport layer may be laminated on the light emitting layer of the light emitting element.
[0022]
In the light emitting device of the present invention, an electron transport layer may be laminated on the light emitting layer of the light emitting element.
[0023]
Furthermore, the light-emitting device of the present invention includes a stacked light-emitting element formed by stacking 10 to 500 light-emitting elements each including a pair of electrodes and a light-emitting layer disposed between the electrodes.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0025]
In the light-emitting device of the present invention, a plurality of light-emitting elements each including a pair of electrodes and a light-emitting layer disposed between the electrodes are disposed on a base material, and a light-emitting surface of the light-emitting element rises with respect to the base material Located in the direction. Thereby, the surface area of the light emitting element can be dramatically increased, and the illuminance can be improved. Here, the rising direction of the light emitting surface of the light emitting element can be set at an angle of about 5 to 90 ° with respect to the substrate surface.
[0026]
Specifically, for example, a plurality of light-emitting elements may be formed in a strip shape, a strip shape, a cylindrical shape, a column shape, a porous shape, or the like, and a plurality of light emitting surfaces may be disposed with the light emitting surface of the light emitting element rising from the substrate. In addition, a strip-like light emitting element may be formed and arranged in a multiple structure such as winding or overlapping. Furthermore, the illuminance can be further improved by using the base material portion on which the light emitting element is disposed as a reflecting material.
[0027]
On the other hand, the expansion of the surface area of the light emitting element causes an increase in current for lighting. Therefore, a large amount of current is required for a light emitting device having a planar structure in high luminance applications. In general, the current-luminance characteristics of the light-emitting element are as shown in FIG. 9, and a luminance loss of 3L−L ′ occurs in the high luminance region with respect to the current consumption three times. However, according to the present invention, the light emitting area can be dramatically increased, so that the luminous flux can be increased and the amount of current per unit area of the light emitting element can be reduced. When the graph of FIG. 9 is rewritten into a graph of luminance change rate with respect to luminance and current, that is, luminance and current efficiency, FIG. 10 is obtained.
[0028]
As shown in FIG. 10, the current efficiency is significantly reduced during high luminance light emission. Thus, it can be seen that by increasing the surface area of the light-emitting element that operates and outputs in a low-luminance region where the rate of change in luminance with respect to current is high, the light-emitting element has higher luminous efficiency and higher illuminance. This is to drive the light emitting element with a current value smaller than the maximum current value that can be passed through the light emitting element in terms of the drive current. Specifically, it is preferably 50% or less of the maximum current value, more preferably 40% or 30% or less. As described above, the light-emitting device of the present invention can provide high illuminance even with low luminance and low power consumption.
[0029]
Note that the maximum current value may be considered as a current value in a voltage region where the current does not increase when the voltage is increased in the current / voltage characteristics of the light emitting element. The graph of the light emission characteristics shown in FIG. 10 is an example, but generally, the current efficiency shows the maximum value when the luminance approaches as much as possible. The maximum value of the rate of change of luminance with respect to current described in this embodiment refers to current efficiency at 1 cd / m ² , and operation output is performed in a low luminance region that is 1/3 or more of this value. In general, the lifetime of the light-emitting element is inversely proportional to the luminance of light emission, but the effect of extending the lifetime of the light-emitting element is also exhibited by using the low luminance region.
[0030]
As the light-emitting element used in the present invention, a light-emitting element having an ordinary general configuration can be used. Therefore, in addition to anode / hole transport layer / light emitting layer / electron transport layer / cathode (DH configuration), anode / hole transport layer / light emitting layer / cathode (SH-A configuration), anode / light emitting layer / electron transport layer / cathode. (SH-B configuration), anode / light emitting layer / cathode (single layer configuration), and the like are possible. Alternatively, a plurality of light emitting elements may be stacked to form one stacked light emitting element.
[0031]
The substrate used in the light emitting element may be any substrate as long as it can support the laminated thin film having the basic configuration described above, and all of these basic configurations are stacked on the substrate. In the case where light is extracted from the side facing the substrate, there are no particular restrictions on the material, form, etc. In the case of extracting light from the substrate side, any transparent or translucent material may be used so that light emission generated in each of the above layers can be extracted, and glass such as Corning 1737, polyester, other resin films, or the like is used.
[0032]
The light emitting element can take out surface emission by making at least one of the electrodes transparent or translucent. Usually, an ITO (indium tin oxide) film is often used for the anode as the hole injection electrode. In addition, tin oxide, Ni, Au, Pt, Pd, or the like is used as the anode. In forming the ITO film, film forming methods such as sputtering, electron beam evaporation, and ion plating are employed for the purpose of improving the transparency or reducing the resistivity. The film thickness is determined from the required sheet resistance value and visible light transmittance, but since the light emitting element has a relatively high driving current density, it is used at a thickness of 100 nm or more in order to reduce the sheet resistance value. There are many cases. For the cathode as the electron injection electrode, an alloy of a metal having a low work function and a low electron injection barrier, such as a MgAg alloy or an AlLi alloy proposed by Tang et al. Many. Further, a metal having a low work function may be formed on the organic layer side, and a metal having a large work function may be thickly laminated for the purpose of protecting the low work function metal, such as Li / Al and LiF / Al. A laminated electrode can be used. In the case of the laminated light emitting device, both electrodes need to be transparent or translucent. In addition to the ITO film, a thin film such as tin oxide, Ni, Au, Pt, Pd, MgAg alloy, or AgPdCu alloy can be used as the cathode at this time. When the light emitting material is an organic material, the organic layer may be damaged. Therefore, it is preferable to provide a phthalocyanine derivative such as dilithium phthalocyanine, a mixed layer of a pyrazaball derivative and an alkali metal, or the like. The formation of these cathodes is preferably vapor deposition or sputtering.
[0033]
As a material constituting the hole transport layer, a derivative having triphenylamine as a basic skeleton is preferable. Examples include tetraphenylbenzidine compounds, triphenylamine trimers, triphenylamine tetramers, and benzidine dimers. Further, it may be a triphenyldiamine derivative or MTPD (N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine). In particular, a triphenylamine tetramer is preferable.
[0034]
As a material constituting the electron transport layer, tris (8-quinolinolato) aluminum (hereinafter referred to as Alq) is preferable. Other examples include metal complexes such as tris (4-methyl-8-quinolinolato) aluminum, 3- (2′-benzothiazolyl) -7-diethylaminocoumarin, and the like. The thickness of the electron transport layer is preferably 10 to 1000 nm.
[0035]
As a material constituting the light emitting layer used in the present invention, in addition to Alq and derivatives thereof, low molecular materials such as 4,4′-bis (2,2-diphenylvinyl) biphenyl and tetraphenylporphine, poly (p- Polymer materials such as phenylene vinylene) and polyfluorene can be used. Further, in order to improve the light emission efficiency or change the light emission color, a light emitting material such as a laser dye may be doped, and tris (2-phenylpyridine) iridium, 2,3,7,8,12,13,17. , 18-octaethylporphyrin platinum (II) or other phosphorescent heavy metal complex may be used. In addition, the hole transport material and the electron transport material may be mixed and present for improving the hole transport capability and the electron transport capability. Further, an inorganic phosphor or the like may be used, and it can be formed by being dispersed in a polymer matrix. The light emitting layer may be only a single material that emits each color such as red, blue, green, yellow, or the like, and a mixed color can be taken out by containing a plurality of materials in the same layer. Further, for example, like the display device such as a CRT, the same layer may be separated into islands and arranged for each emission color. Furthermore, it is good also as a laminated structure which isolate | separates and laminates | stacks a layer for every luminescent color, and superimposes the luminescent color from each layer.
[0036]
As for each of the hole transport layer, the electron transport layer, and the light emitting layer, it is desirable to form a homogeneous film in an amorphous state, and film formation by a vacuum evaporation method is preferable. Furthermore, by continuously forming each layer in a vacuum, it is possible to improve the characteristics such as lower operating voltage, higher efficiency, and longer life by preventing impurities from adhering to the interface between the layers. it can. In addition, when forming each of these layers by a vacuum deposition method, when a plurality of compounds are contained in one layer, it is preferable to co-evaporate each boat containing the compounds by individually controlling the temperature. You may do it. Further, as another film forming method, a solution coating method, a Langmuir-Blodget (LB) method, or the like can be used. In the solution coating method, each compound may be dispersed in a matrix material such as a polymer.
[0037]
Moreover, as a base material which arrange | positions the said light emitting element by this invention, thermoplastic materials, such as an acryl, vinyl chloride, a polypropylene, a polycarbonate, thermosetting resins, such as a melamine and a phenol resin, metal materials, such as glass or stainless steel Etc. can be used.
[0038]
Furthermore, the surface area of the light-emitting element is greatly increased by providing a light-emitting device including a stacked light-emitting element in which 10 to 500 light-emitting elements each including a pair of electrodes and a light-emitting layer disposed between the electrodes are stacked. The amount of current per unit area can be reduced, and a long-life light source can be provided even in high luminance applications.
[0039]
The light-emitting device of this embodiment can create a new illumination space as a new light source for surface light emission by using the light-emitting element with high efficiency. Further, it can be applied to a display device such as a liquid crystal display as a backlight of a white light source or a monochromatic light source. Furthermore, it can be used for a display such as a television.
[0040]
【Example】
Next, the present invention will be described in more detail based on specific examples.
[0041]
(Example 1)
An ITO film was formed as a transparent anode on a polycarbonate substrate having a length of 1 m, a width of 1 m, and a thickness of 0.3 mm. Then, poly (p-phenylene vinylene) was applied to a thickness of 80 nm as a light emitting layer, and Ca was used as an electron injection cathode. A light-emitting film was prepared by vapor-depositing to a thickness of 10 nm and further depositing Al as a cathode to a thickness of 100 nm. This light-emitting film was cut into a strip shape having a length of 5 cm and a width of 30 cm to produce a strip-shaped light emitting device. Next, as shown in FIG. 1, the longitudinal direction of the strip-like light emitting element 10 is set to a groove-like fixture (not shown) of a base material 11 made of acrylic resin having a metal reflection surface and a length of 30 cm and a width of 25 cm. The light emitting device 12 of the present invention was created by inserting and fixing. At this time, the light emitting surface of the belt-like light emitting element was disposed so as to be positioned in a direction perpendicular to the substrate. In addition, the arrangement interval of the respective band-like light emitting elements was 5 mm, and the arrangement number was 50.
[0042]
The light emission efficiency of this light emitting device was 15 lm / W, which was about 1.5 times higher than the light emission efficiency of a single light emitting element illuminated as a surface light source. This is due to the influence of the edge emission of the light emitting element used in the present invention. Further, the area of the light source (the area of the base material) was 750 cm ² , whereas the total area of the light emitting surface of the light emitting element was 7500 cm ² , and the area could be increased 10 times. Thereby, desired illuminance could be obtained even if the light emission luminance of each light emitting element was reduced to 1/10.
[0043]
In addition, as a characteristic of the organic light emitting element, the current efficiency (cd / A) is higher on the lower luminance side, so that the light emitting device has an effect of extending the life. That is, when the normal illuminance at 1 m is 100 lx, the lifetime of the light emitting device is 12000 hours, which is about 13 times the lifetime when the same illuminance is obtained with a vertical light emitting element of 30 cm in length and 25 cm in width. It was.
[0044]
In applications such as partial illumination and indirect illumination, the light emitting device can be produced from the size of the order of 10 cm to the size of the order of 1 m as in this embodiment. According to the present invention, for example, it can take a form covering a large area such as a wall surface or a ceiling surface, and can be created even on the order of 10 m. The length in the major axis direction of the belt-like light emitting element at this time can be arbitrarily set according to the size of the base material to be attached, and a sufficient length is ensured by the mounting form such as a wave shape or a spiral shape. Can do. The length in the minor axis direction is preferably up to about 20% of the size of the substrate.
[0045]
(Example 2)
An ITO film was formed on a glass substrate having a length of 30 cm, a width of 40 cm, and a thickness of 0.5 mm as a transparent anode, and then N, N′-bis (4′-diphenylamino-4-biphenylyl) -N, N′-diphenylbenzidine A hole transport layer having a thickness of 50 nm is formed, and subsequently, 4,4′-bis (carbazol-9-yl) -biphenyl and tris (2-phenylpyridine) iridium as a light emitting layer have a mass of 95: 5. Vaporized to a thickness of 30 nm, (biphenyl-4-olato) bis (2-methyl-8-quinolinolato) aluminum was deposited to a thickness of 10 nm as a blocking layer, and tris (8-quinolinolato) was formed as an electron transport layer. Aluminum was deposited to a thickness of 20 nm, and a laminated cathode composed of 1 nm thick Li and 100 nm thick Al was formed to produce a light emitting plate. The light-emitting plate was cut into a strip shape having a length of 0.8 cm and a width of 1.2 cm to produce a strip-shaped light emitting element. Next, as shown in FIG. 2, the short-axis direction of the strip-like light emitting element 20 is arranged in a groove-like fixture (not shown) of a base material 21 made of acrylic resin having a metal reflection surface and a length of 3 cm and a width of 4 cm. The light emitting device 22 of the present invention was created by being inserted into and fixed to. At this time, the light emitting surface of the strip-shaped light emitting element was disposed so as to be positioned in a direction perpendicular to the substrate. In addition, each strip-shaped light emitting element was arranged in three rows with an interval in the minor axis direction of 2 mm and an interval on the light emitting surface side of 10 mm, and the number of arranged elements was 63.
[0046]
The luminous efficiency of this light emitting device is 30 lm / W, and the efficiency can be improved by about 1.6 times compared to the luminous efficiency of a single light emitting element illuminated as a surface light source. This is due to the influence of the edge emission of the light emitting element used in the present invention. Further, the area of the light source (the area of the base material) was 12 cm ² , whereas the total area of the light emitting surface of the light emitting element was 60.5 cm ² , and the area could be increased by about 5 times. . Thereby, desired illuminance was able to be obtained even if the light emission luminance of each light emitting element was set to 1/5.
[0047]
In addition, as a characteristic of the organic light emitting element, the current efficiency (cd / A) is higher on the lower luminance side, so that the light emitting device has an effect of extending the life. That is, when the normal illuminance 1 m away is 100 lx, the lifetime of this light emitting device is 15000 hours, which is about 6 times the lifetime when the same illuminance is obtained with a 3 cm long and 4 cm wide surface light emitting device. It was.
[0048]
Although this embodiment is applied to a small light-emitting light source, it can be used as a large illumination application as in the first embodiment. In either case, the long axis direction of the strip is preferably up to about 20% of the size of the substrate.
[0049]
(Example 3)
An ITO film is formed as a transparent anode on a straw-shaped polycarbonate with an inner diameter of 2 mm, a length of 50 cm, and a thickness of 0.2 mm, and then immersed in an oligothiophene coating solution to form a light emitting layer by dip coating. A laminated electrode composed of a MgAg alloy having a thickness of 10 nm (Mg: Ag mass ratio of 10: 1) and ITO having a thickness of 100 nm is formed as a cathode, and SiN having a thickness of 1 μm is further formed as a protective film. A tube was created. This arc tube was cut into a 1 cm long cylinder to produce a cylindrical light emitting element. Next, as shown in FIG. 3, the cylindrical light emitting element 30 is fixed to a cylindrical projection (not shown) provided on a stainless steel base 31 having a metal reflection surface and a length of 3 cm and a width of 3 cm. The light emitting device 32 of the present invention was created by being inserted and fixed. Each cylindrical light emitting element was arranged in 7 rows at a pitch of 5 mm, and the number of arrangement was 49.
[0050]
The light emission efficiency of this light emitting device was 8 lm / W, and an increase in efficiency of about 1.5 times that of a single light emitting element illuminated as a surface light source was achieved. This is due to the influence of the edge emission of the light emitting element used in the present invention. Further, the area of the light source (the area of the base material) was 9 cm ² , whereas the total area of the light emitting surface of the light emitting element was 36.9 cm ² , and the area could be increased by about 4 times. . Thereby, desired illuminance was able to be obtained even if the light emission luminance of each light emitting element was set to 1/4.
[0051]
In addition, as a characteristic of the organic light emitting element, the current efficiency (cd / A) is higher on the lower luminance side, so that the light emitting device has an effect of extending the life. That is, when the normal illuminance 1 m away is 100 lx, the lifetime of this light emitting device is 8000 hours, which is about four times the lifetime when the same illuminance is obtained with a 3 cm long and 3 cm wide surface light emitting device. It was.
[0052]
In this embodiment, a straw-like polycarbonate is used, but a columnar one may be used. Moreover, the material may be glass or metal. In the case of a metal, itself can be used as an electrode.
[0053]
Example 4
A porous substrate having a circular shape with a radius of 2 mm and holes with a depth of 1.5 cm formed at intervals of 1 mm was molded with polycarbonate. A 200 nm thick Al was vapor-deposited on the surface of the porous substrate having holes, and then a 1 nm thick Li was vapor-deposited to form a cathode. Subsequently, tris (8-quinolinolato) aluminum was deposited to a thickness of 40 nm as an electron transport layer, and (biphenyl-4-olato) bis (2-methyl-8-quinolinolato) aluminum was formed to a thickness of 10 nm as a blocking layer. As a light emitting layer, 4,4′-bis (carbazol-9-yl) -biphenyl and tris (2-phenylpyridine) iridium were vapor-deposited at a mass ratio of 95: 5 to a thickness of 30 nm, and N, N A hole transport layer having a thickness of 50 nm composed of '-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine was formed. Furthermore, after forming ITO as a transparent anode, a 1 μm-thick SiN film is formed as a protective film, and finally a hole in the porous substrate is filled with a cycloolefin polymer to obtain a light emitting plate having a porous light emitting element. Created. This light-emitting plate was cut into a 6 cm long and 6 cm wide square to produce a light emitting device of the present invention.
[0054]
The luminous efficiency of the light emitting device is 22 lm / W, and the area of the light source (area of the porous substrate) is 36 cm ² , while the total area of the light emitting surface of the light emitting device is 171.6 cm ² . The area could be increased by about 4.8 times. As a result, it was possible to obtain a desired illuminance even when the emission luminance was set to 1/5 as compared with the case of using a flat substrate.
[0055]
Further, as a characteristic of the organic light emitting device, the current efficiency (cd / A) is higher on the lower luminance side, so that the present light emitting device is also effective in extending the lifetime. That is, when the normal illuminance 1 m away is 100 lx, the lifetime of the light emitting device is 8500 hours, which is about four times the lifetime when the same illuminance is obtained with a 6 cm long and 6 cm wide planar light emitting device. It was.
[0056]
(Other examples)
FIG. 4 shows a light emitting device 42 of the present invention in which the band-shaped light emitting element 40 produced in Example 1 is wound up to form a multiple structure, and the band-shaped light emitting element 40 is disposed on a substrate 41. is there.
[0057]
Further, FIG. 5 shows that the strip-shaped light emitting element 50 manufactured in Example 1 is largely wound to form a multi-layer structure, and the strip-shaped light emitting element 50 is disposed on a substrate 51 to form the light emitting device 52 of the present invention. It is what.
[0058]
Further, FIG. 6 shows a light emitting device 62 of the present invention in which a plurality of band-like light emitting elements 60 produced in Example 1 are stacked to form a multiple structure, and the band-like light emitting elements 60 are arranged on a substrate 61. Is.
[0059]
【The invention's effect】
As described above, the light-emitting device of the present invention includes a plurality of light-emitting elements each including a pair of electrodes and a light-emitting layer disposed between the electrodes, and the light-emitting surface of the light-emitting element is provided. By positioning in the rising direction with respect to the base material, the surface area of the light-emitting element can be increased, the amount of current per unit area can be reduced, and a long-life light source can be provided even in high-luminance applications.
[Brief description of the drawings]
FIG. 1 is an external view of a light-emitting device of the present invention using a strip-like light-emitting element.
FIG. 2 is an external view of a light-emitting device of the present invention using a strip-like light-emitting element.
FIG. 3 is an external view of a light emitting device of the present invention using a cylindrical light emitting element.
FIG. 4 is an external view of a light-emitting device of the present invention in which a strip-shaped light-emitting element is wound to form a multiple structure.
FIG. 5 is an external view of a light-emitting device of the present invention in which a strip-shaped light-emitting element is largely wound to form a multiple structure.
FIG. 6 is an external view of a light-emitting device of the present invention in which a strip-shaped light-emitting element is stacked to form a multiple structure.
FIG. 7 is a cross-sectional view of a conventional light emitting device using an uneven light emitting film.
FIG. 8 is a cross-sectional view of a conventional multilayer light emitting device.
FIG. 9 is a graph showing current-luminance characteristics of a light emitting element.
FIG. 10 is a graph showing luminance-current efficiency characteristics of a light-emitting element.
[Explanation of symbols]
10, 20, 30, 40, 50, 60, 70 Light emitting elements 11, 21, 31, 41, 51, 61 Base material 12, 22, 32, 42, 52, 62 Light emitting device 71 Substrate 72 Anode 73 Light emitting layer 74 Cathode 80 Multilayer light emitting device 81, 82, 83 Light emitting device

Claims (13)

On a substrate, a pair of electrodes, the electrodes emitting element and a light-emitting layer are stacked arranged between is a light-emitting device having a plurality disposed on the substrate,
The light emitting surface of the light emitting element is located in the rising direction with respect to the base material ,
Surface emission from the light emitting surface is taken out from the side facing the substrate or the substrate side,
The light emitting device according to claim 1, wherein a current flowing through the light emitting element is 50% or less of a current value in a voltage region where the current does not increase when the voltage is increased in the current-voltage characteristics of the light emitting element .   The light-emitting device according to claim 1, wherein the light-emitting element is formed in a strip shape.   The light emitting device according to claim 1, wherein the light emitting element is formed in a strip shape.   The light emitting device according to claim 1, wherein the light emitting element is formed in a cylindrical shape or a column shape.   The light emitting device according to claim 1, wherein the light emitting element is formed in a porous shape.   The light-emitting device according to claim 1, wherein the light-emitting element is a stacked light-emitting element formed by stacking a plurality of light-emitting elements.   The light emitting device according to claim 1, wherein a light emitting layer of the light emitting element is made of an organic material.   The light emitting device according to claim 1, wherein the light emitting layer of the light emitting element includes a plurality of organic materials having different emission colors.   The light emitting device according to claim 7, wherein the organic material is dispersed.   The light emitting device according to claim 8, wherein the organic material is arranged in an island shape for each emission color.   The light emitting device according to claim 1, wherein a light emitting layer of the light emitting element includes a plurality of layers, and each layer is a layer formed of an organic material having different emission colors.   The light emitting device according to claim 1, wherein a hole transport layer is stacked on the light emitting layer of the light emitting element.   The light emitting device according to claim 1, wherein an electron transport layer is stacked on the light emitting layer of the light emitting element.

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