JP2004342521A - Self-luminous device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-luminous device capable of emitting, from the light extraction side, light of a quantity more than that of a self-luminous device without having an uneven surface formed, and never causing luminance irregularity. <P>SOLUTION: This self-luminous device is so structured that an organic EL element 2 equipped with an organic luminescent layer 21 caught by a pair of electrodes 20 and 22 is formed on a transparent substrate 1; one-side surface of the transparent substrate 1 is formed into an uneven surface 11 having a plurality of uneven parts; in the uneven surface 11, the ratio Ra/Sm of the arithmetic average roughness Ra to the average interval Sm between the uneven parts by JIS B0601-1994 is set to 0.008-0.09; and the EL element 2 is formed on the uneven surface 11 of the transparent substrate 1 along the uneven parts. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a self-luminous device such as an organic electroluminescent device (organic electroluminescent device or organic EL device) or an inorganic electroluminescent device (inorganic electroluminescent device or inorganic EL device) having a light emitting layer sandwiched between a pair of electrodes. The present invention relates to a light emitting device in which an element is formed on a substrate.
[0002]
[Prior art]
Conventionally, lighting devices and displays using self-luminous devices such as organic electroluminescent devices (organic electroluminescent devices and organic EL devices) and inorganic electroluminescent devices (inorganic electroluminescent devices and inorganic EL devices) have been proposed.
[0003]
However, it is known that a self-luminous device has a low percentage of light emitted from the light emitting layer that can be extracted outside the device (light extraction efficiency is low). This is because the layers constituting the self-luminous device have different refractive indexes.
[0004]
For example, also in the bottom emission type organic EL device as shown in FIG. 18, for the same reason as described above, all the light emitted from the organic light emitting layer 211 passes through the first electrode 201 which is a transparent electrode and the transparent substrate 100. The light is not emitted to the outside of the device, but is attenuated inside the device like light h4, or is emitted to the outside from the end of the device like light h5.
[0005]
As described above, in the conventional self-luminous device, all the light generated in the light emitting layer cannot be extracted from the light emitting surface A to the outside of the device.
[0006]
Therefore, a first conventional technique has been proposed in which an uneven surface is provided on a transparent substrate and an organic EL element is formed on the uneven surface (for example, see Patent Document 1). The first conventional technique reflects light trapped in a light emitting film at a step caused by unevenness by providing one pixel for each protrusion or recess, and increases the amount of light that can be extracted to the outside of a transparent substrate. This is a technology related to a display using an inorganic EL device.
[0007]
On the other hand, as an electrode provided on the side opposite to the light extraction side with respect to the light emitting layer, an electrode having light reflectivity such as Al is used, or a light reflection member is provided on the side opposite to the light extraction side. In the case where the light emitted from the light emitting layer to the side opposite to the light extraction side is reflected to the light extraction side to increase the light extraction efficiency, particularly when light is not emitted, light incident from the outside is specularly reflected. There are also problems.
[0008]
Therefore, a second conventional technique has been proposed in which dot-like irregularities are provided at random on a transparent substrate, and a plurality of electrodes, light-emitting layers, and the like are provided on the irregularities (for example, see Patent Document 2). . According to the second conventional technique, reflection of an image due to specular reflection of a metal electrode is prevented.
[0009]
Further, in a liquid crystal display device using an organic EL device on which an organic EL element is formed as a backlight of a liquid crystal display panel, a third prior art in which unevenness is provided on a substrate of the organic EL device has been proposed (for example, Patent Document 3). See). According to the third conventional technique, the substrate is provided with a function as a diffusion plate by providing unevenness, and specular reflection when the organic EL device is used as a reflection plate is prevented.
[0010]
[Patent Document 1]
JP-A-1-186587
[Patent Document 2]
JP-A-2000-40584
[Patent Document 3]
JP-A-9-50031
[0011]
[Problems to be solved by the invention]
However, as in the first related art, even if an uneven surface is provided on a substrate and a light emitting element is formed on the uneven surface, the light extraction efficiency may not be high. This is because, depending on the shape of the unevenness, the amount of light extracted from the light emitting surface to the outside may be smaller than that of a flat self-luminous device having no uneven surface.
[0012]
In addition, depending on the shape of the unevenness, as shown in FIG. 20A, when a self-light emitting element is formed on an uneven surface, the thickness of each layer (especially, a light emitting layer) constituting the self light emitting element changes depending on a location. Or, as shown in (b), a part where the electrodes come into contact with each other occurs.
As shown in (a), a portion (for example, B in the figure) where the thickness of the light emitting layer 211 is thinner than other portions (for example, C in the diagram) has a lower resistance than the other portions, so that the current is low. Easy to flow. Therefore, the luminance becomes higher than other portions. Further, when a large amount of current flows, the temperature of this portion becomes higher, the resistance becomes lower, the current flows more, and the luminance becomes higher. For this reason, the created device may have uneven brightness. Further, due to this phenomenon, a large amount of current flows to a specific portion of the light emitting layer 211, and the element life of the portion is shortened. As a result, the period during which the device can be used may be limited. .
As shown in (b), when a portion where the light emitting layer 211 is not provided (for example, E in the drawing) is formed, a large amount of current flows through this portion. Therefore, current does not easily flow through the light emitting layer 211 (for example, D in the figure), and sufficient luminance may not be obtained in some cases.
[0013]
Further, the self-luminous device is required to have high luminance in a specific direction. This is because a user who uses / views light from a self-luminous device is usually in a specific direction with respect to the self-luminous device (generally, a normal direction of a light extraction side / light extraction surface of the self-luminous device). Because.
[0014]
On the other hand, when used as a reflector as in the third related art, it is necessary to not only prevent specular reflection but also increase the luminance of reflected light in a specific direction. For example, when used as a backlight of a liquid crystal display device, as shown in FIG. 21, in a usage environment of the liquid crystal display device 8, a direction in which a light source 9 such as the sun or a fluorescent lamp is assumed (generally, When light is incident from the direction of θ = about 20 to 40 degrees, preferably about θ = 30 degrees with respect to the normal line H of the display surface 80, not only does not specularly reflect, but also the normal line of the display surface 80 The luminance in the H direction (approximately θ = 0 degrees) must be high.
[0015]
The present invention has been made in view of the above problems, and has a substantially larger amount of light emitted from the light extraction side than a self-luminous device having no uneven surface, and has a self-luminous device without luminance unevenness. A first object is to provide a light emitting device.
It is a second object of the present invention to provide a self-luminous device having a high luminance in a specific direction on the light emitting side.
Furthermore, when used as a reflector, not only does not reflect specular, but also provides a self-luminous device with high brightness in a specific direction when light is incident from the direction in which the light source is assumed to be third. Aim.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the first self-luminous device according to the present invention has a self-luminous element including a light-emitting layer sandwiched between a pair of electrodes formed on a substrate, and the substrate has one surface, The uneven surface has a plurality of unevenness, and the uneven surface satisfies any of the following conditions (i), (iii), (v), and (vii). In addition, it is characterized by being formed along irregularities.
(I) The ratio Ra / Sm of the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.09 or less.
(Iii) The ratio Ra / S of the arithmetic average roughness Ra according to JIS B0601-1994 and the average interval S between local peaks is 0.009 or more and 0.10 or less.
(V) The ratio Rz / Sm of the ten-point average roughness Rz to the average interval Sm of the unevenness according to JIS B0601-1994 is 0.05 or more and 0.22 or less.
(Vii) The ratio Rz / S of the ten-point average roughness Rz and the average interval S between local peaks according to JIS B0601-1994 is 0.05 or more and 0.25 or less.
[0017]
Further, if the uneven surface is designed to satisfy any one of the following conditions (ii), (iv), (vi), and (viii), a self-luminous device having better light reflection characteristics can be obtained. It becomes possible.
(Ii) The ratio Ra / Sm between the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.03 or less.
(Iv) The ratio Ra / S of the arithmetic average roughness Ra and the average interval S between local peaks according to JIS B0601-1994 is 0.009 or more and 0.03 or less.
(Vi) The ratio Rz / Sm of the ten-point average roughness Rz to the average interval Sm of the unevenness according to JIS B0601-1994 is 0.05 or more and 0.14 or less.
(Viii) The ratio Rz / S between the ten-point average roughness Rz and the average distance S between local peaks according to JIS B0601-1994 is 0.048 or more and 0.12 or less.
[0018]
In a second self-luminous device according to the present invention, a self-luminous element including a light-emitting layer sandwiched between a pair of electrodes is formed on a substrate, and the above-described (i) to (i) are provided between the substrate and the self-luminous element. The light emitting device has an intermediate layer having an uneven surface satisfying any of the conditions of viii), and the self-luminous element is formed along the uneven surface on the uneven surface of the intermediate layer. With this self-luminous device, it is possible to obtain the same or more advantageous effects as those of the first self-luminous device.
[0019]
In a third self-luminous device according to the present invention, a self-luminous element having a light-emitting layer sandwiched between a pair of electrodes is formed on a substrate, and the electrode provided on the substrate side has the above-mentioned ( An uneven surface satisfying any one of the conditions (i) to (viii) is formed, and the light emitting layer and other electrodes are formed along the unevenness. With this self-luminous device, it is possible to obtain the same or more advantageous effects as those of the first self-luminous device.
[0020]
In the first to third self-luminous devices, the surface provided with the unevenness (the uneven surface) satisfies the following condition (a) or (b), respectively.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer.
[0021]
In the first to third self-luminous devices, a prism sheet may be provided on a side from which light emitted from the light-emitting layer is extracted with reference to the light-emitting layer.
Further, the first to third self-luminous devices are particularly effective when the self-luminous element is an organic electroluminescent element.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIGS. 1 to 17, the components denoted by the same reference numerals indicate equivalent or similar components. First, the first organic EL device will be described.
[0023]
《First organic EL device》
In the first organic EL device, as shown in FIG. 1, one surface (light incident surface) 11 of the transparent substrate 1 is provided with a plurality of irregularities, and the organic EL element 2 is formed on the light incident surface 11. A bottom emission type organic EL device.
[0024]
<Substrate 1>
The substrate 1 is a plate-shaped transparent member that supports the organic EL element 2 and is a light incident surface 11 on which the organic EL element 2 is formed, and a light provided on a side facing the light incident surface 11. And an emission surface 10. Light is incident on the substrate 1 from the organic EL element 2 via the light incident surface 11, and the incident light is emitted from the light emitting surface 10 to the outside of the device.
[0025]
The first organic EL device is characterized in that the light incident surface 11 is formed with a plurality of irregularities and satisfies the following condition (i).
(I) The ratio Ra / Sm of the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.09 or less.
[0026]
In addition, in order to impart good reflection characteristics to the organic EL device, the light incident surface 11 should satisfy the following condition (ii) instead of the above condition (i).
(Ii) The ratio Ra / Sm between the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.03 or less.
[0027]
It is to be noted that the light incident surface 11 which is an uneven surface satisfies the following condition (a) or (b) regardless of whether any of the above conditions (i) and (ii) is adopted.
This is because when Sm or S is equal to or more than the lower limit described below, geometrical optical simulation can be performed, and design of optical characteristics of an organic EL device to be manufactured becomes extremely easy.
Further, if Sm or S is equal to or more than the following upper limit value, it becomes substantially the same as a plane. In other words, this is because there is almost no change from the state in which the unevenness is not provided.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer.
[0028]
The substrate 1 can support / form the organic EL element 2 and may be formed of any material as long as it is transparent. In general, a glass substrate, a quartz substrate, a plastic substrate, or the like is selected. Further, a substrate composed of a composite sheet in which a plurality of the same or different types of substrates are combined can also be used.
[0029]
In this specification, “transparent” means that the light transmittance with respect to light extracted to the outside of the element is 50% or more, preferably 80% or more, and desirably 90% or more, and is generally about 400 to 800 nm. Light (visible light) having a wavelength of? If the transmittance is too low, the light emission from the light emitting layer itself is attenuated, and it becomes difficult to obtain the luminance required for the light emitting element.
[0030]
The inventors of the present application have found out that the organic EL device under the above conditions should be used from the following examples and comparative examples.
In Examples and Comparative Examples, the ratio Ra / Sm between the arithmetic average roughness Ra of the light incident surface 11 and the average interval Sm of the unevenness is appropriately changed to a value of 0.001 or more and 0.10, and the light incident surface ( Fabrication of an organic EL device under the same conditions (material, film thickness, manufacturing method, etc.) except that S or Sm of the uneven surface (11) satisfies one of the above conditions (a) and (b). did. Hereinafter, a method for manufacturing an organic EL device as an example and a comparative example will be described.
[0031]
First, on the light incident surface of the plate-shaped transparent substrate, a portion which is convex with respect to the light emitting surface is patterned with a photoresist using a mask, and is etched in this state, so that the light incident surface 11 having irregularities is formed. Was formed. After the formation of the light incident surface 11, the arithmetic average roughness Ra of the light incident surface 11 and the average interval Sm of the irregularities were measured by a roughness meter.
After the measurement, a first electrode (thickness: 50 nm) 20 as a transparent electrode made of ITO was formed on the light incident surface 11 by an RF sputtering method. After preparing the first electrode 20, an organic light emitting layer (a hole injection / transport layer formed of TPTE, 80 nm: an organic light emitting material formed by co-evaporation of DPVBi (93.0% by weight) and BCzVBi (7.0% by weight)) Containing layer, 30 nm: electron injection transport layer formed of 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1,1-dimethyl-3,4-diphenylsilole, 20 nm) 21 is vacuum Vapor deposition equipment (carbon crucible, vapor deposition rate 0.1 nm / s, degree of vacuum about 5.0 × 10 ^-5 Pa), and then a tungsten board (deposition rate 1 nm / s, vacuum degree about 5.0 × 10 ^-5 Pa) to form an aluminum layer (second electrode) 22 having a thickness of 150 nm, thereby manufacturing an organic EL device. The produced organic EL device was sealed with a known protective film (passivation film).
[0032]
[Evaluation 1]
The same current was applied to each of the manufactured organic EL devices, and the total amount of light emitted from the light emitting surface 10 was measured using a luminance meter. Ra / Sm on the light incident surface 11 of each organic EL device and the magnitude of luminance were plotted on the graph of FIG. The magnitude of the luminance is based on the luminance of the organic EL device in which the organic EL element 2 is formed as described above except that the light incident surface 11 is not provided with irregularities, and is expressed as a ratio to this luminance (luminance ratio). expressed.
[0033]
From the experimental results shown in FIG. 2, the inventors of the present application show that when Ra / Sm is 0.008 or more, the Ra / Sm is extracted from the light emitting surface to the outside as compared with a conventional organic EL device having a flat light incident surface. We found that the amount of light increased.
In other words, it has been found that simply providing irregularities on the light incident surface may result in a smaller amount of light extracted from the light emitting surface to the outside than in a conventional organic EL device.
[0034]
[Evaluation 2]
The luminance in the normal direction of the light exit surface 10 when the organic EL element 2 is irradiated with constant light from a position at 30 degrees to the normal line of the light exit surface 10 without causing the organic EL element 2 to emit light is measured by the luminance measurement. It measured with the instrument. Ra / Sm on the light incident surface 11 of each organic EL device and the magnitude of the luminance in the normal direction of the light emitting surface 10 were plotted in the graph of FIG. As described above, the magnitude of the luminance is based on the luminance of the organic EL device in which the organic EL element 2 is formed as described above except that no irregularities are provided on the light incident surface 11, and the ratio (luminance) to this luminance is used. Ratio).
[0035]
According to FIG. 3, the inventors set the Ra / Sm to be 0.008 or more and 0.03 or less, out of the light incident at an angle of 30 degrees with respect to the normal to the light exit surface, the method of the light exit surface was considered. It has been found that the ratio of light reflected in the linear direction is 1.8 times or more that of a conventional organic EL device having a flat light incident surface, and extremely higher than other angles.
When Ra / Sm is more than 0 and equal to or less than 0.09, of the light incident from the angle of 30 degrees with respect to the normal to the light emitting surface, the light reflected in the normal direction of the light emitting surface. Was found to be larger than when the light incident surface 11 was not provided with irregularities.
[0036]
In the organic EL device having Ra / Sm of more than 0 and not more than 0.09, unlike the conventional organic EL device in which the light incident surface 11 is not provided with irregularities, there was no specular reflection.
Further, it was confirmed that the same effect as described above was obtained even when constant light was irradiated from any position of 20 to 40 degrees with respect to the normal line of the light emitting surface 10.
[0037]
[Evaluation 3]
Furthermore, as a result of producing organic EL devices each having the organic EL element 2 formed as described above except that Ra / Sm was set to 0.10, 0.13, and 0.15, these organic EL devices were allowed to emit light. At that time, uneven brightness was visually confirmed. On the other hand, in the organic EL device having Ra / Sm of 0.008 or more and 0.09 or less, no luminance unevenness was observed when emitting light.
[0038]
The above results indicate that it is difficult to form an organic EL element, particularly an organic light emitting layer, with a uniform film thickness over the entire surface when Ra / Sm on the light incident surface exceeds 0.09. Can be attributed to this. That is, it is considered that a portion where the film thickness of the organic light emitting layer is thick and a portion where the film thickness is thin are generated, and the brightness of the thin portion is increased as described above, and uneven brightness is confirmed.
Further, it is considered that the unevenness having a steep slope such that Ra / Sm exceeds 0.09 has a portion where the organic light emitting layer is not formed, and the leak between the electrodes has occurred.
Next, the organic EL element 2 in the first organic EL device will be described.
[0039]
<Organic EL device 2>
As shown in FIG. 1, the organic EL element 2 includes a pair of electrodes 20 and 22 sandwiching an organic light emitting layer 21 as a light emitting layer containing an organic light emitting material. (Light of a predetermined wavelength / light of a predetermined chromaticity). In the first organic EL device, a known organic EL element can be appropriately used, except that the organic EL element 2 is provided on the light incident surface 11 of the substrate 1 along the uneven shape of the light incident surface 11. .
[0040]
[First electrode 20]
In the first organic EL device, the first electrode 20 is required to be transparent because it is provided on the light extraction side of the organic light emitting layer 21. The first electrode 20 may be either an anode or a cathode, but the material for forming the first electrode (transparent electrode) is preferably a material that can efficiently inject carriers (holes / electrons) into the organic light emitting layer 21. .
[0041]
In general, a material having a work function of 4.5 eV to 5.5 eV is preferable as the anode. Specifically, tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium oxide (In ₂ O ₃ ), Tin oxide (SnO) ₂ ) And zinc oxide (ZnO) are preferred.
These oxides may deviate somewhat from their stoichiometric composition. In in ITO ₂ O ₃ SnO against ₂ Is preferably 1 to 20 wt%, more preferably 5 to 12 wt%. In in IZO ₂ O ₃ Is usually about 12 to 32 wt%. If the average value of the entire transparent electrode 1 has such a composition, the transparent electrode 1 may have a concentration gradient in the film thickness direction.
In addition, Sn, Ti, Pb, and the like may be contained in the form of oxide in an amount of 1 wt% or less in terms of oxide.
[0042]
The cathode is an electrode for injecting electrons into the organic layer, and has a work function of, for example, less than 4.5 eV, generally 4.0 eV or less, and typically 3.7 eV or less in order to increase electron injection efficiency. , Electrically conductive compounds and mixtures thereof are employed as electrode materials.
As such materials, those listed as materials that can be used for the anode can also be used, and the following materials can also be used.
For example, an electrode formed by laminating a transparent conductive oxide on an ultra-thin magnesium-silver alloy is used. Further, in this cathode, a buffer layer containing copper phthalocyanine or the like may be provided between the cathode and the organic light emitting layer 21 in order to prevent the light emitting layer and the like from being damaged by plasma when the conductive oxide is sputtered. .
[0043]
[Organic light emitting layer 21]
The organic light emitting layer 21 transports and recombines at least one of the carriers (electrons and holes) injected from the first electrode 21 and the second electrode 22 to form an exciton. This layer emits electroluminescence (light) when returning, and is mainly made of an organic material.
[0044]
The organic material may be a material that gives the organic light emitting layer 21 a function higher than that required for the organic light emitting layer 21, or a material having a different function may be given to the organic light emitting layer 21. As such a material, a material used for an organic light emitting layer of a known organic EL element, such as Alq3 or DCM, may be appropriately adopted.
[0045]
Furthermore, the organic light emitting layer 21 may have a laminated structure, and the functions described above may be shared among the respective layers. In this case, a layer containing a material (organic light emitting material) such as a fluorescent material or a phosphorescent material that generates electroluminescence is particularly referred to as an organic light emitting material containing layer.
For example, an electron injection layer or an electron injection transport layer having a function of injecting electrons from the cathode may be provided at the interface with the cathode. In addition, an electron transport layer having an electron transport function may be provided between the cathode or the electron injection layer and the organic light emitting material containing layer. A hole injection layer or a hole injection transport layer having a function of injecting holes from the anode may be provided, or a hole transport layer having a hole transport function may be provided.
As a layer configuration to be adopted and a material constituting the layer, a layer configuration and a material similar to those of a known organic EL element may be appropriately adopted.
[0046]
The emission color can be adjusted by appropriately adjusting the emission color of a known organic EL element. For example, the following adjustment method can be adopted.
Selection of the type of material (organic light emitting material) that gives the organic light emitting layer 21 a function of emitting electroluminescence when returning from the exciton to the ground state.
Adjustment of the organic material added to the organic light emitting layer 21 and the mixing ratio of the organic light emitting material.
-Adjustment of the amount of the organic light emitting material mixed.
-Adjustment of the film thickness of the organic light emitting layer 21.
-A known color filter layer is provided on the organic EL device to limit the wavelength of light emitted to the outside of the device.
Mixing a known wavelength conversion material that changes the wavelength of incident light.
-By mixing a plurality of organic light emitting materials, a plurality of colors are emitted, and the added color is expressed.
Adjust the emission color by adding a material that promotes or inhibits emission.
Adjust the luminescent color by the amount of current flowing through the organic luminescent layer 21.
[0047]
[Second electrode 22]
The second electrode 22 is a cathode when the first electrode is an anode, and is an anode when the first electrode is a cathode. Therefore, any material that satisfies the above-described conditions required for the anode / cathode and that is used for a known organic EL element can be appropriately used, and the above-described material for forming the first electrode 20 can be used. You can also.
[0048]
However, light emitted from the organic light emitting layer 21 to the side opposite to the light extraction side is reflected to the light extraction side to increase the light extraction efficiency of the device, or the light emitted from the light extraction side when the organic EL element 2 is not emitting light. The second electrode 22 preferably has a light reflection function in order to reflect the reflected light to the light extraction side. The material that imparts the light reflecting function to the second electrode 22 satisfies the above-described conditions required for the anode / cathode, and includes light having a wavelength emitted from the organic light emitting layer 21 and light incident from the outside. In addition, a metal, an alloy, or the like that has a property of at least reflecting light having a wavelength extracted from the light incident surface 11 to the outside of the device and is used in a known organic EL element can be appropriately used.
[0049]
In addition, layers and members other than those described above, which are used in known organic EL devices, can be appropriately combined and used. For example, without providing the second electrode 22 with a light reflection function, a light reflection member may be provided on the side opposite to the light extraction side with respect to the organic light emitting layer 21. A semi-reflective member (half mirror) may be provided.
Next, a method for manufacturing the first organic EL device will be described.
[0050]
<Production method>
The first organic EL device includes a well-known substrate processing method for forming a plurality of fine irregularities satisfying the above-mentioned conditions on the light incident surface 11 of the substrate 1, and a layer forming the organic EL element 2 on the light incident surface 11. It can be manufactured by using a known method for manufacturing an organic EL element which is sequentially formed. For example, it may be manufactured as follows.
[0051]
First, as shown in FIG. 4A, a flat transparent substrate 1 'is prepared. One surface (light incident surface) 11 'of the transparent substrate 1' is patterned with a photoresist or the like using a mask having a pattern corresponding to the arrangement of the concave portions and convex portions to be formed. Then, etching is performed in this state to form the uneven surface 11 as shown in FIG.
[0052]
Next, as shown in FIG. 4C, the first electrode 20, the organic light emitting layer 21, and the second electrode 22 are formed on the light incident surface 11 of the transparent substrate 1 along the surface of the layer in contact with the substrate 1 side. Are sequentially laminated so as to have irregularities. Since each layer is formed to have a uniform film pressure, each layer has a curved shape corresponding to the light incident surface 11 of the transparent substrate 1. As a lamination method, a lamination method of each layer in a known organic EL element may be appropriately adopted, and for example, a known thin film formation method such as a vacuum evaporation method, a sputtering method, a spin coating method, a casting method, and an LB method can be employed. .
An organic EL device can be manufactured as described above.
[0053]
The light incident surface 11 of the transparent substrate 1 can adopt another substrate processing method instead of forming it by etching. For example, a surface treatment method using sandblasting can be adopted. Alternatively, the substrate 1 having the light incident surface 11 may be manufactured by pouring molten transparent resin or glass into a mold having an uneven inner surface.
[0054]
<Effects>
Since the organic EL device according to the present embodiment has the above configuration, the following operation and effect can be obtained.
[0055]
・ High light extraction efficiency and extremely low brightness unevenness
Since the light incident surface is set as described above, higher light extraction efficiency can be obtained than in a conventional organic EL device having a flat light incident surface, and the probability of occurrence of luminance unevenness is extremely low.
In other words, a performance that cannot be obtained simply by providing irregularities on the light incident surface is obtained.
[0056]
・ Improvement of brightness in specific direction
At the time of light emission, the luminance in a specific direction is higher than the luminance in other directions with reference to the light emitting surface. It has also been found that this specific direction can be changed by changing Ra / Sm.
This is considered to be due to the concave light condensing effect and the reflection and refraction due to the unevenness.
Therefore, the organic EL device according to the present embodiment is required to make the luminance in a specific direction higher than the luminance in other directions. For example, the organic EL device is used for a display, a lighting device, a backlight of a liquid crystal display device, and the like. It was also found to be a suitable device.
[0057]
・ High light emission
Since the organic EL element 2 is formed along the unevenness on the light incident surface 11 which is an uneven surface, the amount (light emitting area) of the organic light emitting layer 21 is smaller than that of a conventional organic EL device having a flat light incident surface. The amount of light emission increases.
Further, since Ra / Sm is set in the above-described range, the possibility that a place where the organic light emitting layer 21 is not provided, that is, a place where the electrodes leak, is extremely low. Since most of the generated current passes through the organic light emitting layer 21, the luminous efficiency increases.
[0058]
・ Improvement of reflection characteristics
Since the organic EL device is designed as described above, when the organic EL device is used as a reflector, a light source located at about 20 to 40 degrees (generally about 30 degrees) with respect to the normal line of the light emitting surface 10 is used as a reference. Most of the incident light can be reflected in the normal direction of the light exit surface 10.
Further, since minute unevenness is formed on each layer of the light incident surface 11 and the organic EL element 2, specular reflection can be prevented.
[0059]
・ Improved chromaticity characteristics
At the time of light emission, the chromaticity becomes uniform in each emission direction on the light emission side 10.
This is because fine irregularities are formed on each layer of the light incident surface 11 and the organic EL element 2, so that light of each wavelength can be diffused in various directions, and light of each wavelength can be diffused in the light exit surface 10. It is considered that the angle dependency of the luminance of the image became extremely small.
[0060]
<Another example>
Note that the first organic EL element can be modified as follows. Further, the following modifications can be used in combination as appropriate.
[0061]
[Alternative Example 1: Providing Irregularities in Intermediate Layer]
Instead of providing irregularities on the light incident surface 11 of the substrate 1, an intermediate layer 3 is provided between the substrate 1 and the organic EL element 2 as shown in FIG. Even if the uneven surface 30 having a plurality of unevenness, which satisfies the above condition (i), is formed, and the organic EL element is formed along the uneven surface 30, the same effect as described above can be obtained.
In addition, when the above condition (ii) is employed instead of the above condition (i), good light reflection characteristics can be obtained.
Also in this case, the uneven surface 30 satisfies the following condition (a) or (b) for the reason described above.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer.
[0062]
Such an organic EL device can be manufactured, for example, as follows. As shown in FIG. 6A, a transparent intermediate layer 3 'having a predetermined thickness is formed on the surface of a flat transparent substrate 1'. The surface of the intermediate layer 3 ′ is patterned with a photoresist or the like using a mask having a pattern corresponding to the arrangement of the concave portions and the convex portions to be formed, and is etched in this state, as shown in FIG. An uneven surface 30 as shown is formed.
Then, as shown in FIG. 6C, the first electrode 20 which is a transparent electrode on the uneven surface 30, the organic light emitting layer 21 on the first electrode 20, and the reflective electrode on the organic light emitting layer 21. Are sequentially laminated to a uniform thickness. When formed in this manner, each layer is formed so as to have unevenness along the uneven shape of the layer existing on the intermediate layer 3 side. Since each layer is formed with a uniform thickness, each layer has a curved shape according to the uneven surface 30 of the intermediate layer 3. Thus, an organic EL device as shown in FIG. 5 is manufactured.
[0063]
Note that, instead of the above-described etching method, a method of forming an intermediate layer using half exposure and focus offset by photolithography can also be adopted. That is, a photoresist may be used as the intermediate layer.
Further, the uneven surface 30 of the intermediate layer 3 may be formed by a surface treatment using sandblasting or the like instead of being formed by etching.
Further, a sheet made of a transparent resin or the like having an uneven surface formed in advance may be attached on the transparent substrate 1 to form the intermediate layer 3. Also, instead of forming irregularities on the surface of the transparent layer 3 having a uniform thickness formed on the transparent substrate 1, first, a transparent film is formed only on a portion of the transparent substrate 1 where a convex portion is to be formed. After that, by forming a transparent film on the entire surface of the transparent film and the transparent substrate 1, an uneven surface can be obtained.
[0064]
The material for forming the intermediate layer 3 is a material that is transparent when the intermediate layer 3 is formed, has high adhesiveness to the substrate 1 and the organic EL element 2 (first electrode 20), and Any material can be used as long as the material hardly causes a chemical or physical influence on the substrate 1 or the substrate 1. For example, a polyester resin or an acrylic resin can be used.
Further, the intermediate layer 3 may have a function other than forming the uneven surface 30. For example, if the refractive index of the intermediate layer 3 is a layer having an intermediate value between the organic EL element (first electrode 20) and the transparent substrate 1, the organic EL element 2 has a higher refractive index than the organic EL device without the intermediate layer 3. The amount of light entering the transparent substrate 1 increases. Further, the intermediate layer may contain a wavelength conversion material or a scattering member.
When an additive is added to the organic EL element 2 (particularly, the organic light emitting layer 21), the light emitting characteristics and the like of the organic EL element 2 are changed. The intermediate layer 3 can be contained in the intermediate layer 3 by preparing the intermediate layer 3 from a material having resistance to the above-mentioned additives.
Further, if the intermediate layer 3 is used, it is possible to use even a substrate on which unevenness cannot be formed / difficult.
[0065]
[Alternative Example 2: Irregularities are provided on the electrode on the light extraction side of the light emitting layer]
Instead of providing irregularities on the light incident surface 11 of the substrate 1, as shown in FIG. 7, an electrode provided on the substrate side of the electrodes, that is, the first electrode 20 on the organic light emitting layer 21 side is subjected to the above-mentioned condition (i). The same effect can be obtained by forming the uneven surface 20a having a plurality of unevenness and forming the organic light emitting layer 21 and the second electrode (other electrode) 22 along the unevenness. .
If the condition (ii) is used instead of the condition (i), a better reflection function can be obtained.
Also in this case, the uneven surface 30 satisfies the following condition (a) or (b) for the reason described above.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer.
[0066]
Such an organic EL device can be manufactured, for example, as follows. As shown in FIG. 8A, a first electrode 20 'which is a transparent electrode having a predetermined film thickness is formed on the surface of a flat transparent substrate 1. The surface of the first electrode 20 ′ is patterned with a photoresist or the like using a mask having a pattern corresponding to the arrangement of the concave portions and the convex portions to be formed, and is etched in this state, as shown in FIG. An uneven surface 20a as shown is formed.
Then, as shown in FIG. 8C, the organic light emitting layer 21 is formed on the uneven surface 20 a of the first electrode 20, and the second electrode 22 as a reflective electrode is formed on the organic light emitting layer 21. The organic light emitting layer 21 and the second electrode 22 are formed so as to have irregularities along the surface of the layer in contact with the first electrode 20 side. Since each layer is formed with a uniform thickness, each layer has a curved shape according to the uneven surface 20 a of the first electrode 20. Thus, an organic EL device as shown in FIG. 7 is manufactured.
[0067]
Note that the uneven surface 20a of the first electrode 20 can be formed by a surface treatment using sandblasting or the like instead of being formed by etching.
Also, instead of forming irregularities on the surface of the first electrode 20 having a uniform thickness formed on the transparent substrate 1, first, the transparent electrode is formed only on the portion of the transparent substrate 1 where the projection is to be formed. By forming a transparent film made of the above material and further forming a transparent film of the same material on the entire surface of the transparent film and the transparent substrate 1, the uneven surface 20a can be obtained.
Further, when a desirably transparent or opaque electrode having a lower resistivity than the first electrode 20 is used instead of the transparent film, the potential in the plane of the first electrode 20 can be made more uniform, and uneven brightness can be obtained. Can be extremely reduced. Further, the resistance of the first electrode 20 can be reduced.
Similarly, after the transparent electrode 20 is provided with a uniform film thickness, an uneven surface 20a is formed by forming a transparent or opaque electrode having a lower resistivity than the transparent electrode, preferably a transparent or opaque electrode, on the portion where the protrusion is to be formed. Is also good. This also makes it possible to extremely reduce luminance unevenness and lower the resistance of the first electrode 20.
As described above, it is possible to employ a substrate in which it is difficult to provide unevenness.
[0068]
[Another Example 3: Inorganic EL Element]
In the above embodiment, a self-luminous device in which an inorganic EL element is formed instead of the organic EL element 2 may be used. As shown in FIG. 9, the inorganic EL element 4 has a three-layer inorganic structure in which an inorganic light emitting material containing layer 412 mainly composed of an inorganic material such as zinc sulfide is sandwiched between a pair of insulating layers 411 and 413 such as silicon oxide. A light emitting layer 41 is sandwiched between a transparent first electrode 40 and a second electrode 42 made of metal or the like and also functioning as a reflective layer. When a high AC voltage of about 200 V is applied between the electrodes, electrons emitted from the interface between the inorganic light emitting layer 412 and the insulating layers 411 and 413 are accelerated, and the dopant atoms in the inorganic light emitting layer 412 are When excited, light (electroluminescence) is generated, and this light is emitted from the transparent electrode 40 side to the outside of the device.
[0069]
[Alternative Example 4: Providing a prism sheet]
As shown in FIG. 10, one or more prism sheets 5 may be provided on the light extraction side with respect to the light emitting layer.
As described above, the organic EL device according to the present embodiment can increase the luminance in a specific direction according to the arithmetic average inclination Δa of the uneven surface. Therefore, if one or a plurality of prism sheets 5 for changing the traveling direction of the light emitted in the specific direction to the normal direction of the light emission surface are provided on the light extraction side, the normal direction of the light emission surface, that is, the device Can be increased in the front direction. Naturally, it is also possible to set the luminance in other directions high.
As the prism sheet 5, a known optimal sheet may be appropriately selected according to the emission characteristics of the organic EL device, and the combination of the organic EL device and the prism sheet 5 can be realized using a known combination method or a combination member. .
[0070]
[Alternative Example 5: Used as a backlight of a liquid crystal display device]
The first organic EL device may be used as a lighting device.
Further, it can be suitably used as a backlight (back light source) of a liquid crystal display device. This is because, as described above, the first organic EL device has a larger light extraction amount, less luminance unevenness, high reflection characteristics, and no specular reflection as compared with the conventional organic EL device. . Therefore, when the first organic EL device is used as a backlight of a liquid crystal display device, the brightness is higher, the brightness unevenness is less, and even when no light is emitted, than when the conventional organic EL device is used as a backlight. The display can be clearly recognized.
[0071]
For example, as shown in FIG. 11, a known transmissive liquid crystal display panel or semi-transmissive liquid crystal display panel is adopted as the liquid crystal display panel 6, and the non-display surface 61 faces the light emitting surface 10 of the organic EL device. Placed in That is, the liquid crystal display panel 6 is arranged such that the display surface 60 is visible from outside the liquid crystal display device.
In this liquid crystal display device, when the outside of the device is sufficiently bright, the display on the liquid crystal display panel 6 can be viewed well without turning on the organic EL element 2. If there is not sufficient brightness outside the device, the display on the liquid crystal display panel 6 can be visually recognized by illuminating the organic EL element 2.
As described above, the organic EL device equipped with the first organic medical EL device as a backlight enables clear display even in a bright place such as under sunlight, or in a dark place such as indoors or at night. . In addition, when the external light is sufficiently bright, it is not necessary to illuminate the organic EL element 2, so that power consumption can be reduced as compared with a conventional liquid crystal display device having a backlight.
[0072]
[Alternative Example 6: Display]
A display may be formed by combining the first organic EL device with a known organic EL element driving method. As a driving method for the organic EL element, for example, a passive matrix method or an active matrix method may be used.
[0073]
In the passive matrix system, in an XY matrix electrode configuration including scanning electrodes and signal electrodes, a display element (organic EL element 2) is connected to each grid point forming a matrix, and the organic EL element 2 is driven (light emission) by line-sequential driving. ) Is done.
[0074]
The active matrix method is a driving method including a switching element and a holding element for each display element (organic EL element 2), that is, for each pixel / subpixel. The display element (organic EL element 2) is arranged at a matrix intersection between the scanning electrode and the signal electrode. It is preferable to use a TFT for the switch.
[0075]
[Alternative example 7: Change light extraction side]
The first organic EL device is not limited to the bottom emission type, and light may be extracted from another portion to the outside of the device.
For example, in the case of a top emission type organic EL device, the substrate 1 and the first electrode 20 need not be transparent, and the second electrode 22 is a transparent electrode, and light emitted from the organic light emitting layer 21 is What is necessary is just to take it out of a device via the 2nd electrode 22. If the first electrode 20 is a reflective electrode or a light reflecting plate is provided on the side opposite to the light extraction side with respect to the organic light emitting layer 21, the light is emitted from the organic light emitting layer 21 to the first electrode 20 side. Part or all of the emitted light can be extracted to the outside of the device via the second electrode 22.
Hereinafter, the second organic EL device will be described.
[0076]
<< Second organic EL device >>
The second organic EL device can be configured similarly to the first organic EL device except for the following points, and can be modified similarly to the first organic EL device.
[0077]
In the second organic EL device, the light incident surface 11 satisfies the following condition (iii), and the organic EL element 2 is formed along the layer on the light incident surface 11 side. It has a curved shape according to the unevenness formed on the side layer.
(Iii) The ratio Ra / S of the arithmetic average roughness Ra according to JIS B0601-1994 and the average interval S between local peaks is 0.009 or more and 0.10 or less.
[0078]
When the second organic EL device has a reflection function as described above, the following condition (iv) may be provided instead of the condition (iii).
(Iv) The ratio Ra / S of the arithmetic average roughness Ra and the average interval S between local peaks according to JIS B0601-1994 is 0.009 or more and 0.03 or less.
[0079]
Even when the condition (iii) or (iv) is satisfied, the light emitting surface 11 satisfies the following condition (a) or (b) for the above-described reason.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer.
[0080]
Even with such a design, the same operation and effect as those of the first organic EL device can be obtained.
As described above, an uneven surface may be provided on the intermediate layer 3 or an uneven surface may be provided on the first electrode 20.
[0081]
The inventors of the present application have found that the organic EL device should be within such a range from the following examples and comparative examples.
In Examples and Comparative Examples, the ratio Ra / S between the arithmetic average roughness Ra of the light incident surface 11 and the average interval S of the local peaks was appropriately changed so as to be in the range of 0.001 or more and 0.15 or less. Except for the above, each organic EL device was manufactured under the same conditions (material, film thickness, manufacturing method, etc.) as those of the above-mentioned Example and Comparative Example in the first organic EL device.
[0082]
[Evaluation 4]
The same current was applied to each of the manufactured organic EL devices, and the total amount of light emitted from the light emitting surface 10 was measured using a luminance meter. Ra / S on the light incident surface 11 of each organic EL device and the magnitude of luminance were plotted on the graph of FIG. The magnitude of the luminance was a luminance ratio based on the luminance of the organic EL device in which the organic EL element 2 was formed as described above except that no irregularities were provided on the light incident surface 11.
[0083]
From the experimental results shown in FIG. 12, the inventors of the present application show that when Ra / S is set to 0.009 or more, light is extracted from the light emitting surface to the outside as compared with a conventional organic EL device having a flat light incident surface. We found that the amount of light increased.
In other words, it has been found that simply providing irregularities on the light incident surface may result in a smaller amount of light extracted from the light emitting surface to the outside than in a conventional organic EL device.
[0084]
[Evaluation 5]
The luminance in the normal direction of the light exit surface 10 when the organic EL element 2 is irradiated with constant light from a position at 30 degrees to the normal line of the light exit surface 10 without causing the organic EL element 2 to emit light is measured by the luminance measurement. It measured with the instrument. The Ra / S on the light incident surface 11 of each organic EL device and the magnitude of the luminance in the normal direction of the light emitting surface 10 were plotted in the graph of FIG. The magnitude of the luminance was represented by a luminance ratio with respect to the luminance of the organic EL device in which the organic EL element 2 was formed as described above, except that the light incident surface 11 was not provided with irregularities.
[0085]
The inventors set that Ra / S is 0.009 or more and 0.03 or less from FIG. 13, and when the light incident from the angle of 30 degrees with respect to the normal line of the light emission surface, the light emission surface It has been found that the ratio of light reflected in the linear direction is 1.5 times or more that of a conventional organic EL device having a light incident surface which is flat and extremely higher than other angles.
When Ra / S is set to more than 0 and equal to or less than 0.10, of the light incident at an angle of 30 degrees with respect to the normal to the light emitting surface, the light reflected in the normal direction of the light emitting surface. Was found to be larger than when the light incident surface 11 was not provided with irregularities.
[0086]
It was confirmed that the organic EL device having Ra / S of more than 0 and not more than 0.10 did not perform specular reflection unlike the conventional organic EL device in which the light incident surface 11 was not provided with irregularities.
Further, it was confirmed that the same effect as described above was obtained even when constant light was irradiated from any position of 20 to 40 degrees with respect to the normal line of the light emitting surface 10.
[0087]
[Evaluation 6]
Furthermore, organic EL devices were formed as described above except that Ra / S was changed to 0.12, 0.15, and 0.18, respectively. As a result, these organic EL devices were allowed to emit light. At that time, uneven brightness was visually confirmed. On the other hand, in the organic EL device having Ra / S of 0.009 or more and 0.10 or less, no luminance unevenness could be confirmed when emitting light.
[0088]
The above results indicate that it is difficult to form an organic EL element, particularly an organic light emitting layer, with a uniform film thickness over the entire surface when Ra / S on the light incident surface exceeds 0.10. Can be attributed to this. That is, it is considered that a portion where the film thickness of the organic light emitting layer is thick and a portion where the film thickness is thin are generated, and the brightness of the thin portion is increased as described above, and uneven brightness is confirmed. In addition, it is considered that the unevenness having a steep slope such that Ra / S exceeds 0.10 has a portion where the organic light emitting layer is not formed, and a leak between the electrodes has occurred.
Next, a third organic EL device according to the present embodiment will be described.
[0089]
《Third organic EL device》
The third organic EL device can be configured similarly to the first organic EL device except for the following points, and can be modified similarly to the first organic EL device.
[0090]
In the third organic EL device, the light incident surface 11 satisfies the following condition (v), and the organic EL element 2 is formed along the layer on the light incident surface 11 side. It has a curved shape according to the unevenness formed on the side layer.
(V) The ratio Rz / Sm of the ten-point average roughness Rz to the average interval Sm of the unevenness according to JIS B0601-1994 is 0.05 or more and 0.22 or less.
[0091]
When the third organic EL device has a reflection function as described above, the following condition (vi) may be provided instead of the above condition (v).
(Vi) The ratio Rz / Sm of the ten-point average roughness Rz to the average interval Sm of the unevenness according to JIS B0601-1994 is 0.05 or more and 0.14 or less.
[0092]
Even when the condition (v) or (vi) is satisfied, the light emitting surface 11 satisfies the following condition (a) or (b) for the above-described reason.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer.
[0093]
Even with such a design, the same operation and effect as those of the first organic EL device can be obtained.
As described above, an uneven surface may be provided on the intermediate layer 3 or an uneven surface may be provided on the first electrode 20.
[0094]
The inventors of the present application have found that the organic EL device should be within such a range from the following examples and comparative examples.
In Examples and Comparative Examples, the ratio Rz / Sm between the ten-point average roughness Rz of the light incident surface 11 and the average interval Sm of the irregularities is appropriately changed so as to be in the range of 0.01 or more and 0.0.30 or less. Except for the above, each organic EL device was manufactured under the same conditions (material, film thickness, manufacturing method, etc.) as those of the above-mentioned Example and Comparative Example in the first organic EL device.
[0095]
[Evaluation 7]
The same current was applied to each of the manufactured organic EL devices, and the total amount of light emitted from the light emitting surface 10 was measured using a luminance meter. Rz / Sm on the light incident surface 11 of each organic EL device and the magnitude of luminance were plotted on the graph of FIG. The magnitude of the luminance was based on the luminance of the organic EL device in which the organic EL element 2 was formed as described above except that the light incident surface 11 was not provided with irregularities, and a ratio (luminance ratio) to this luminance was shown. .
[0096]
From the experimental results shown in FIG. 14, the inventors of the present application show that when Rz / Sm is 0.05 or more, the light is extracted from the light emission surface to the outside as compared with a conventional organic EL device having a flat light incidence surface. We found that the amount of light increased.
In other words, it has been found that simply providing irregularities on the light incident surface may result in a smaller amount of light extracted from the light emitting surface to the outside than in a conventional organic EL device.
[0097]
[Evaluation 8]
The luminance in the normal direction of the light exit surface 10 when the organic EL element 2 is irradiated with constant light from a position at 30 degrees to the normal line of the light exit surface 10 without causing the organic EL element 2 to emit light is measured by the luminance measurement. It measured with the instrument. The Rz / Sm on the light incident surface 11 of each organic EL device and the magnitude of the luminance in the normal direction of the light emitting surface 10 are plotted in the graph of FIG. The magnitude of the luminance was represented by a luminance ratio based on the luminance of the organic EL device in which the organic EL element 2 was formed as described above except that the light incident surface 11 was not provided with irregularities. .
[0098]
When the inventors set Rz / Sm to be 0.05 or more and 0.14 or less from FIG. 15, the inventors of the present application show that, of the light incident from the angle of 30 degrees with respect to the normal to the light emitting surface, It has been found that the ratio of light reflected in the linear direction is 1.5 times or more that of a conventional organic EL device having a light incident surface which is flat and extremely higher than other angles.
When Rz / Sm is more than 0 and equal to or less than 0.22, of the light incident from the angle of 30 degrees with respect to the normal to the light emitting surface, the light reflected in the normal direction of the light emitting surface. Was found to be larger than when the light incident surface 11 was not provided with irregularities.
[0099]
It has been found that, in the organic EL device having an Rz / Sm of more than 0 and not more than 0.22, unlike the conventional organic EL device in which the light incident surface 11 is not provided with irregularities, there is no specular reflection.
Further, it was confirmed that the same effect as described above was obtained even when constant light was irradiated from any position of 20 to 40 degrees with respect to the normal line of the light emitting surface 10.
[0100]
[Evaluation 9]
Furthermore, organic EL devices were formed as described above except that Rz / Sm was set to 0.03, 0.04, and 0.05, respectively. As a result, these organic EL devices were allowed to emit light. At that time, uneven brightness was visually confirmed. On the other hand, in the organic EL device having Rz / Sm of 0.05 or more and 0.22 or less, no luminance unevenness was observed when light was emitted.
[0101]
The above results show that it is difficult to form an organic EL element, particularly an organic light emitting layer, with a uniform film thickness over the entire surface when Rz / Sm of the light incident surface exceeds 0.22. Can be attributed to this. That is, it is considered that a portion where the film thickness of the organic light emitting layer is thick and a portion where the film thickness is thin are generated, and the brightness of the thin portion is increased as described above, and uneven brightness is confirmed. In addition, it is considered that the unevenness having a steep slope such that Rz / Sm exceeds 0.22 causes a portion where the organic light emitting layer is not formed, thereby causing a leak between the electrodes.
Next, a fourth organic EL device according to the present embodiment will be described.
[0102]
《Fourth organic EL device》
The fourth organic EL device can be configured similarly to the first organic EL device except for the following points, and can be modified similarly to the first organic EL device.
[0103]
In the fourth organic EL device, the light incident surface 11 satisfies the following condition (vii), and the organic EL element 2 is formed along the layer on the light incident surface 11 side. It has a curved shape according to the unevenness formed on the side layer.
(Vii) The ratio Rz / S of the ten-point average roughness Rz and the average interval S between local peaks according to JIS B0601-1994 is 0.05 or more and 0.25 or less.
[0104]
When the fourth organic EL device has a reflection function as described above, the following condition (viii) may be provided instead of the above condition (vii).
(Viii) The ratio Rz / S between the ten-point average roughness Rz and the average distance S between local peaks according to JIS B0601-1994 is 0.048 or more and 0.12 or less.
[0105]
Even when the condition (vii) or (viii) is satisfied, the light emitting surface 11 satisfies the following condition (a) or (b) for the above-described reason.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer.
[0106]
Even with such a design, the same operation and effect as those of the first organic EL device can be obtained.
Note that, as described above, the intermediate layer 3 may have an uneven surface, or the first electrode 20 may have an uneven surface.
[0107]
The inventors of the present application have found that the organic EL device should be within such a range from the following examples and comparative examples.
In the examples and the comparative examples, the ratio Rz / S between the ten-point average roughness Rz of the light incident surface 11 and the average interval S of the local peaks was appropriately changed so as to be in the range of 0.01 or more and 0.03 or less. Except for the above, each organic EL device was manufactured under the same conditions (material, film thickness, manufacturing method, etc.) as those of the above-mentioned Example and Comparative Example in the first organic EL device.
[0108]
[Evaluation 10]
The same current was applied to each of the manufactured organic EL devices, and the total amount of light emitted from the light emitting surface 10 was measured using a luminance meter. The Rz / S on the light incident surface 11 of each organic EL device and the magnitude of luminance were plotted on the graph of FIG. The magnitude of the luminance was represented by a luminance ratio with respect to the luminance of the organic EL device in which the organic EL element 2 was formed as described above, except that the light incident surface 11 was not provided with irregularities.
[0109]
From the experimental results shown in FIG. 16, the inventors of the present application show that when Rz / S is set to 0.05 or more, light is extracted from the light emission surface to the outside as compared with a conventional organic EL device having a flat light incidence surface. We found that the amount of light increased.
In other words, it has been found that simply providing irregularities on the light incident surface may result in a smaller amount of light extracted from the light emitting surface to the outside than in a conventional organic EL device.
[0110]
[Evaluation 11]
The luminance in the normal direction of the light exit surface 10 when the organic EL element 2 is irradiated with constant light from a position at 30 degrees to the normal line of the light exit surface 10 without causing the organic EL element 2 to emit light is measured by the luminance measurement. It measured with the instrument. The Rz / S of the light incident surface 11 of each organic EL device and the magnitude of the luminance in the normal direction of the light emitting surface 10 are plotted in the graph of FIG. As described above, the magnitude of the luminance is based on the luminance of the organic EL device in which the organic EL element 2 is formed as described above except that the light incident surface 11 is not provided with irregularities, and a ratio to this luminance (luminance ratio). It was represented by
[0111]
The inventors set that Rz / S to be 0.048 or more and 0.12 or less from FIG. 17, out of the light incident at an angle of 30 degrees with respect to the normal line of the light emission surface, the method of the light emission surface It has been found that the ratio of light reflected in the linear direction is 1.5 times or more that of a conventional organic EL device having a flat light incident surface and extremely higher than other angles.
When Rz / S is set to more than 0 and equal to or less than 0.25, of the light incident at an angle of 30 degrees with respect to the normal to the light emitting surface, the light reflected in the normal direction of the light emitting surface. Was found to be larger than when the light incident surface 11 was not provided with irregularities.
[0112]
In addition, it has been found that an organic EL device having an Rz / S of more than 0 and not more than 0.25 does not perform specular reflection unlike a conventional organic EL device in which the light incident surface 11 is not provided with irregularities.
Further, it was confirmed that the same effect as described above was obtained even when constant light was irradiated from any position of 20 to 40 degrees with respect to the normal line of the light emitting surface 10.
[0113]
[Evaluation 12]
Furthermore, as a result of producing organic EL devices each having the organic EL element 2 formed as described above except that Rz / S was set to 0.30, 0.35, and 0.40, these organic EL devices were allowed to emit light. At that time, uneven brightness was visually confirmed. On the other hand, in an organic EL device having an Rz / S of 0.05 or more and 0.25 or less, no luminance unevenness was observed when light was emitted.
[0114]
The above results indicate that it is difficult to form an organic EL element, particularly an organic light emitting layer, with a uniform film thickness over the entire surface when Rz / S of the light incident surface exceeds 0.25. Can be attributed to this. That is, it is considered that a portion where the film thickness of the organic light emitting layer is thick and a portion where the film thickness is thin are generated, and the brightness of the thin portion is increased as described above, and uneven brightness is confirmed. In addition, it is considered that the unevenness having a steep slope such that Rz / S exceeds 0.25 has a portion where the organic light emitting layer is not formed, and a leak between the electrodes has occurred.
In other words, the luminance uniformity required for the organic EL device may not be achieved only by providing the light incident surface with irregularities, or the luminance may be lower than that of a conventional organic EL device having a flat light incident surface. I found that there are times when it ends up.
[0115]
【The invention's effect】
As is clear from the above invention, according to the present invention, the amount of light emitted from the light extraction side is substantially larger than that of the self-luminous device having no uneven surface, and the self-luminous device has no luminance unevenness. A light emitting device can be provided.
Further, it is possible to provide a self-luminous device having high luminance in a specific direction on the light emitting side. Furthermore, when used as a reflector, it is possible to provide a self-luminous device that not only does not perform specular reflection but also has high luminance in a specific direction when light is incident from a direction in which a light source is assumed to be present.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration example of a first organic EL device according to an embodiment.
FIG. 2 is a graph plotting the relationship between Ra / Sm and the light extraction amount of a first organic EL device.
FIG. 3 shows the relationship between Ra / Sm of the first organic EL device and the luminance in the normal direction when a certain amount of light is irradiated from a position at 30 degrees with respect to the normal direction of the light emitting surface 10. It is the graph which plotted the relationship.
FIG. 4 is a cross-sectional view for explaining a production example of a first organic EL device.
FIG. 5 is a sectional view showing a configuration of a first modification of the first organic EL device.
FIG. 6 is a cross-sectional view for explaining an example of producing the organic EL device shown in FIG.
FIG. 7 is a cross-sectional view illustrating a configuration of a second modification of the first organic EL device.
FIG. 8 is a cross-sectional view for explaining a production example of the organic EL device shown in FIG.
FIG. 9 is a cross-sectional view showing a configuration in which an organic EL element 2 in the first organic EL device is replaced with an inorganic EL element 4.
FIG. 10 is a cross-sectional view illustrating a configuration of a device (display, lighting device, or the like) in which a prism sheet is combined with a first organic EL device.
FIG. 11 is a cross-sectional view showing a state where the first organic EL device is incorporated in a backlight of a liquid crystal display device.
FIG. 12 is a graph plotting the relationship between Ra / S and the light extraction amount of the second organic EL device.
FIG. 13 shows the relationship between Ra / S of the second organic EL device and the luminance in the normal direction when a certain amount of light is irradiated from a position at 30 degrees to the normal direction of the light emitting surface 10. It is the graph which plotted the relationship.
FIG. 14 is a graph plotting the relationship between Rz / Sm and the light extraction amount of the third organic EL device.
FIG. 15 shows the relationship between Rz / Sm of the third organic EL device and luminance in the normal direction when a certain amount of light is irradiated from a position at 30 degrees with respect to the normal direction of the light emitting surface 10. It is the graph which plotted the relationship.
FIG. 16 is a graph plotting the relationship between Rz / S and the light extraction amount of the fourth organic EL device.
FIG. 17 shows the relationship between Rz / S of the fourth organic EL device and the luminance in the normal direction when a certain amount of light is irradiated from a position at 30 degrees with respect to the normal direction of the light emitting surface 10. It is the graph which plotted the relationship.
FIG. 18 is a cross-sectional view showing a conventional bottom emission type organic EL device and a problem of the device.
FIG. 19 is a cross-sectional view for explaining a problem of a conventional self-luminous device having unevenness on a light incident surface side of a substrate 100.
FIG. 20 is a cross-sectional view for explaining a problem when a self-luminous device is incorporated as a backlight of a liquid crystal display device.
[Explanation of symbols]
1 substrate
10 Light exit surface
11 Light incident surface (uneven surface)
2 Organic EL element (self-luminous element)
20, 40 First electrode
20a Uneven surface
21, 41 organic light emitting layer (light emitting layer)
411, 413 inorganic insulating layer
412 Inorganic light emitting material containing layer
22, 42 second electrode
3 Middle layer
30 Uneven surface
4 Inorganic EL element (self-luminous element)
5 Prism sheet
6, 8 LCD panel
60 Display surface
61 Non-display side

Claims (12)

A self-light-emitting device having a light-emitting element having a light-emitting layer sandwiched between a pair of electrodes formed on a substrate,
One surface of the substrate is an irregular surface having a plurality of irregularities, and the irregular surface satisfies the following condition (i) and satisfies the following condition (a) or (b);
The self-luminous device is characterized in that the self-luminous element is formed on the uneven surface of the substrate along the unevenness.
(I) The ratio Ra / Sm of the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.09 or less.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer. A self-light-emitting device having a light-emitting element having a light-emitting layer sandwiched between a pair of electrodes formed on a substrate,
An intermediate layer having the following condition (i) and having an uneven surface satisfying the following condition (a) or (b):
The self-luminous device is characterized in that the self-luminous element is formed on the uneven surface of the intermediate layer along the unevenness.
(I) The ratio Ra / Sm of the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.09 or less.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer. A self-light-emitting device having a light-emitting element having a light-emitting layer sandwiched between a pair of electrodes formed on a substrate,
Among the electrodes, the electrode provided on the substrate side has the following condition (i) on the light emitting layer side, and has an uneven surface that satisfies the following condition (a) or (b):
The self-luminous device, wherein the light emitting layer and the other electrode are formed along the irregularities.
(I) The ratio Ra / Sm of the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.09 or less.
(A) The average interval Sm of the unevenness according to JIS B0601-1994 is 3 times or more and 200 times or less of the longest wavelength of the light emitted from the light emitting layer.
(B) The average distance S between local peaks according to JIS B0601-1994 is 3 times or more and 200 times or less as long as the longest wavelength of light emitted from the light emitting layer. The self-luminous device according to any one of claims 1 to 3, wherein the condition (i) is replaced by the following (ii).
(Ii) The ratio Ra / Sm between the arithmetic average roughness Ra and the average interval Sm of irregularities according to JIS B0601-1994 is 0.008 or more and 0.03 or less. The self-luminous device according to any one of claims 1 to 3, wherein the condition (i) is replaced by the following (iii).
(Iii) The ratio Ra / S of the arithmetic average roughness Ra according to JIS B0601-1994 and the average interval S between local peaks is 0.009 or more and 0.10 or less. The self-luminous device according to any one of claims 1 to 3, wherein the condition (i) is replaced by the following (iv).
(Iv) The ratio Ra / S of the arithmetic average roughness Ra and the average interval S between local peaks according to JIS B0601-1994 is 0.009 or more and 0.03 or less. The self-luminous device according to any one of claims 1 to 3, wherein the condition (i) is replaced by the following (v).
(V) The ratio Rz / Sm of the ten-point average roughness Rz to the average interval Sm of the unevenness according to JIS B0601-1994 is 0.05 or more and 0.22 or less. The self-luminous device according to any one of claims 1 to 3, wherein the condition (i) is replaced by the following (vi).
(Vi) The ratio Rz / Sm of the ten-point average roughness Rz to the average interval Sm of the unevenness according to JIS B0601-1994 is 0.05 or more and 0.14 or less. The self-luminous device according to any one of claims 1 to 3, wherein the condition (i) is replaced by the following (vii).
(Vii) The ratio Rz / S of the ten-point average roughness Rz and the average interval S between local peaks according to JIS B0601-1994 is 0.05 or more and 0.25 or less. The self-luminous device according to any one of claims 1 to 3, wherein the condition (i) is replaced by the following (viii).
(Viii) The ratio Rz / S between the ten-point average roughness Rz and the average distance S between local peaks according to JIS B0601-1994 is 0.048 or more and 0.12 or less. It is a self-luminous device according to any one of claims 1 to 10,
The self-luminous device is further characterized in that a prism sheet is provided on a side from which light emitted from the light-emitting layer is extracted with reference to the light-emitting layer. It is a self-luminous device according to any one of claims 1 to 11,
A self-luminous device, wherein the self-luminous element is an organic electroluminescent element.

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