JP2006294491A - ELECTROLUMINESCENT DEVICE, ELECTROLUMINESCENT DEVICE MANUFACTURING METHOD, ELECTRONIC DEVICE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL device capable of suppressing total reflection between a substrate and an electrode and improving light extraction efficiency.
An EL device 100 according to the present invention includes a pair of electrodes 8 and 9 for holding a light emitting layer 5, a substrate 2 on which one electrode 8 of the pair of electrodes is disposed, The uneven portion 2A provided on the surface on which the electrode 8 is disposed, and the planarizing insulating film 4 interposed between the one electrode 8 and the substrate 2 to flatten the uneven portion 2A, The planarization insulating film 4 includes fine particles 3 having a refractive index larger than that of the insulating material 4A serving as a base material. The average refractive index of the planarization insulating film 4 including the fine particles 3 is the substrate 2. The refractive index is adjusted so as to be larger than the refractive index.
[Selection] Figure 1

Description

  The present invention relates to an electroluminescence device, a method for manufacturing an electroluminescence device, and an electronic apparatus.

In recent years, development of EL devices using EL (electroluminescence) elements, which are self-luminous elements, as pixels has been underway. An EL element has a configuration in which a functional layer such as a light emitting layer is sandwiched between an anode and a cathode. Recently, an organic element that employs a method in which a liquid material in which an organic material is dissolved is arranged on a substrate by an inkjet method. An EL device is being developed. In such an organic EL device, a partition member for partitioning each pixel is provided on the substrate, and the liquid material is discharged into a region surrounded by the partition member, so that an organic functional layer is accurately formed on the substrate. (See, for example, Patent Documents 1 and 2).
JP 2001-76864 A Japanese Patent Laid-Open No. 2004-22438

In such an EL device, when light is extracted from the light emitting layer through the transparent substrate, light is totally reflected at the interface between the transparent substrate and the electrode, and the light is confined to emit light from the light emitting layer. There was a problem that only part of the light contributed to the display. In general, ITO is used for the display-side electrode of the EL device, and a glass substrate is used for the transparent substrate. These refractive indexes are about 2.0 for ITO and about 1.5 for a glass substrate, and a large difference in refractive index occurs between them. The light emitting layer emits light in all directions, but light emitted at a wide angle (greater than the critical angle) repeats total reflection within the ITO electrode and cannot be extracted to the transparent substrate side. That is, since the light extraction efficiency is poor, even if light is emitted by supplying a predetermined current to the light emitting layer, only a part of the light contributes to display.
The present invention has been made in view of such circumstances, and an object thereof is to provide an electroluminescence device capable of suppressing total reflection between a substrate and an electrode and improving light extraction efficiency. To do. It is another object of the present invention to provide a method for manufacturing such an electroluminescence device and an electronic apparatus that can emit light with high luminance and includes the electroluminescence device.

In order to solve the above problems, an electroluminescence device of the present invention includes a pair of electrodes for holding a light emitting layer, a substrate on which one of the pair of electrodes is disposed, and the one electrode in the substrate. And an uneven portion provided on the surface on which the electrode is disposed, and a planarization insulating film that is interposed between the one electrode and the substrate and planarizes the uneven portion, the planarizing insulating film Includes fine particles having a refractive index larger than that of the base insulating material, and the average refractive index of the planarization insulating film containing the fine particles is adjusted to be larger than the refractive index of the substrate. It is characterized by being.
According to this configuration, since the planarization insulating film contains fine particles having a high refractive index, the average refractive index of the planarization insulating film is increased. The total reflection conditions at the interface can be relaxed. For this reason, conventionally, light that has been confined by total reflection inside the electrode can be extracted, and the light extraction efficiency can be improved. In this case, the refractive index between the planarization insulating film and the substrate is larger than that of the conventional one, but the substrate is provided with an uneven portion, so that total reflection at the interface between the substrate and the planarization insulating film is avoided. be able to.

In the present invention, the fine particles may have a refractive index larger than that of the one electrode. As such a material, inorganic materials such as zirconium oxide (ZrO ₂ ) and titanium oxide (TiO ₂ ) can be suitably used.
According to this configuration, the refractive index of the planarization insulating film can be made to approach or exceed the refractive index of the one electrode. Thus, by increasing the refractive index of the planarization insulating film, total reflection can be made more difficult to occur.

In the present invention, the average refractive index of the planarization insulating film in the portion containing the fine particles is adjusted to be equal to or higher than the refractive index of the one electrode. can do.
According to this configuration, total reflection does not occur at the interface between the planarization insulating film and the one electrode.

In the present invention, the one electrode may be an electrode on the side from which display light is emitted.
In this case, the one electrode may be formed on the surface of the planarization insulating film. This configuration is a so-called bottom emission type configuration.
The planarization insulating film may include an adhesive layer, and the one electrode and the substrate may be bonded via the adhesive layer. This configuration is a so-called top emission type configuration. In this configuration, the substrate functions as a sealing substrate.

  In the present invention, the fine particles may be contained in the adhesive layer. The planarization insulating film may include a color filter layer, and the color filter layer may include the fine particles. In this case, the fine particles can also serve as a coloring material for the color filter layer.

  In the present invention, the one electrode is an electrode opposite to a side from which display light is emitted, and is emitted toward the substrate side between the planarization insulating film and the substrate. A reflection surface that reflects light toward the light emitting layer may be provided. This configuration is a so-called top emission type configuration.

The method for producing an electroluminescent device of the present invention is a method for producing an electroluminescent device comprising a pair of electrodes for holding a light emitting layer and a substrate on which one of the pair of electrodes is disposed. Forming a concavo-convex portion on the substrate; forming a planarization insulating film for planarizing the concavo-convex portion on the surface of the concavo-convex portion; and placing the one electrode on the surface of the flattening insulating film. The step of forming the planarizing insulating film includes causing the insulating material to be a base material to contain fine particles having a refractive index larger than that of the insulating material, and including the base material and the fine particles. And adjusting the average refractive index of the film so as to be higher than the refractive index of the substrate.
According to this method, since the average refractive index of the planarization insulating film increases because the planarization insulating film contains fine particles having a high refractive index, the electrode and the planarization insulating film are compared with the conventional one. The total reflection conditions at the interface can be relaxed. For this reason, conventionally, light that has been confined by total reflection inside the electrode can be extracted, and the light extraction efficiency can be improved. In this case, the refractive index between the planarization insulating film and the substrate is larger than that of the conventional one, but the substrate is provided with an uneven portion, so that total reflection at the interface between the substrate and the planarization insulating film is avoided. be able to.

In the present invention, the fine particles may be made of a material having a refractive index larger than that of the one electrode.
According to this method, the refractive index of the planarization insulating film can be made to approach or exceed the refractive index of the one electrode. Thus, by increasing the refractive index of the planarization insulating film, total reflection can be made more difficult to occur.

In the present invention, the average refractive index of the planarization insulating film in the interface portion may be adjusted so as to be larger than the refractive index of the one electrode.
According to this method, total reflection does not occur at the interface between the planarization insulating film and the one electrode.

The electronic apparatus of the present invention includes the electroluminescence device of the present invention described above or the electroluminescence device manufactured by the manufacturing method of the present invention described above.
According to this configuration, it is possible to provide an electronic apparatus including an electroluminescence device with high light extraction efficiency.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, an EL device (electroluminescence device) in which EL elements are arranged as pixels on a substrate, particularly an organic EL device in which a light emitting layer is formed of an organic light emitting material will be described as an example. This organic EL device can be suitably used as display means for electronic devices, for example.

[First Embodiment]
[Organic EL device]
FIG. 1 is a cross-sectional view showing a schematic configuration of the organic EL device according to the first embodiment of the present invention.
The organic EL device 100 of the present embodiment is a so-called bottom emission type organic EL device that extracts light (display light) emitted from the light emitting layer 5 from the substrate 2 side. The organic EL device 100 has a configuration in which an organic EL element 10 that is a light emitting element is disposed on the upper surface of a substrate 2. The organic EL element 10 includes a first electrode 8, a hole transport layer 6, a light emitting layer 5, an electron transport layer 7, and a second electrode 9 on one side (upper surface in FIG. 1) side of the substrate 2. It is the structure which laminated | stacked in order. In the present embodiment, the first electrode 8 is an anode and the second electrode 9 is a cathode, but these can be reversed. In this case, a structure in which a cathode, an electron transport layer, a light emitting layer, a hole transport layer, and an anode are laminated in this order from the substrate 2 side. The hole transport layer 6, the light emitting layer 5, and the electron transport layer 7 form a functional layer (organic functional layer) 11 made of an organic functional material.

  Although not shown, the organic EL device according to the present embodiment is an active matrix type. In practice, a plurality of data lines and a plurality of scanning lines are arranged in a grid pattern, and the matrix is divided into these data lines and scanning lines. The organic EL element 10 is connected to each pixel arranged in a shape through a driving TFT such as a switching transistor or a driving transistor. When a drive signal is supplied via the data line or the scanning line, a current flows between the electrodes, the organic EL element 10 emits light, light is emitted to the outer surface side of the substrate 2, and the pixel is lit.

  In the present embodiment, since the display light is extracted from the substrate 2 side, a transparent substrate such as glass is used for the substrate 2. For the anode 8, a light-transmitting conductive film such as ITO (indium tin oxide) is used. On the other hand, for the cathode 9, a conductive film having good light reflectivity, for example, a highly reflective metal film such as Al (aluminum) can be suitably used. In this case, the cathode 9 has a function of reflecting the light generated in the light emitting layer 5 to the anode 8 side. In addition to Al, Au (gold), Ag (silver), Cr (chromium), Cu (copper), Ni (nickel), Ca, Mg (magnesium), Sr, Yb (ytterbium), Er (erbium) ), Tb (terbium), Sm (samarium), and the like, and a structure in which a plurality of thin films of metal materials selected from these are stacked.

  The light emitting material that can constitute the light emitting layer 5 is a known polymer light emitting material capable of emitting fluorescence or phosphorescence, which is a polyfluorene derivative (PF), a polyparaphenylene vinylene derivative (PPV), a polyphenylene derivative ( PP), polyparaphenylene derivative (PPP), polyvinylcarbazole (PVK), polythiophene derivative, polydialkylfluorene (PDAF), polyfluorenebenzothiadiazole (PFBT), polyalkylthiophene (PAT), polymethylphenylsilane (PMPS) Such as polysilanes can be suitably used. In addition, these light-emitting materials include polymer materials such as perylene dyes, coumarin dyes, rhodamine dyes, rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6, quinacridone, and the like. It is also possible to use a low molecular weight material doped.

The hole transport layer 6 enhances the efficiency of charge injection from the anode 8 to the light emitting layer 5 and has a function of blocking electrons moving in the light emitting layer 5, thereby regenerating the electrons and holes in the light emitting layer. There is an effect of increasing the coupling probability. For the hole transport layer 6, a material having a low injection barrier from the anode 8 and a high hole mobility is preferably used. As such a material, for example, a polythiophene derivative, a polypyrrole derivative, or a doped body thereof is used. Specifically, a dispersion of 3,4-polyethylenedioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) [trade name; Bytron-p: manufactured by Bayer], that is, polystyrene as a dispersion medium A dispersion liquid in which 3,4-polyethylenedioxythiophene is dispersed in sulfonic acid and then dispersed in water is used.
If necessary, the efficiency of electron injection from the cathode 9 to the light emitting layer 5 may be increased, and the electron transport layer 7 having a hole blocking function may be formed. The electron transport layer 7 can be formed of an organic material such as an oxadiazole derivative or Alq ₃ .

  Here, in the present embodiment, the uneven portion 2A is provided on the surface of the substrate 2 on the side where the anode 8 is disposed. Between the anode 8 and the substrate 2, a planarization insulating film 4 for planarizing the uneven portion 2 </ b> A is provided, and the anode 8 is disposed on the surface of the planarization insulating film 4. The concavo-convex portion 2 </ b> A is provided to prevent total reflection at the interface between the planarization insulating film 4 and the substrate 2. When the concavo-convex portion 2A exists in this manner, the total reflection condition at the interface between the substrate 2 and the planarization insulating film 4 is relaxed, so that almost all of the light incident on the planarization insulating film 4 is on the substrate 2 side. Will be taken out of. Further, the planarization insulating film 4 also serves to flatten the unevenness of the electrode surface that causes display defects. That is, in the organic EL element 10, the thickness of the organic functional layer 11 including the light emitting layer 5 is very thin. Therefore, if there are irregularities on the surface of the anode 8, there is a possibility that short-circuiting between electrodes or uneven light emission may occur. In the present embodiment, since the surface of the anode 8 is planarized by the planarization insulating film 4, these problems do not occur.

The planarizing insulating film 4 includes fine particles 3 having a refractive index larger than that of the insulating material 4A as a base material at least at the interface with the anode 8, and the interface including the fine particles 3 is included. The average refractive index n _{B of the} partial planarization insulating film 4 is adjusted to be larger than the refractive index n _C of the substrate 2.

In general, ITO is used for the display-side electrode (anode) 8 of the organic EL device, and a glass substrate is used for the substrate 2. The refractive index of ITO is 1.95 (refractive index n _A ; based on the wavelength of 550 nm. The same applies hereinafter), and the glass substrate is 1.54 (refractive index n _C ). There is a difference in refractive index. When such a large difference in refractive index exists, total reflection tends to occur at the interface between the anode 8 and the substrate 2, and even if light is emitted, only a part of the light can contribute to display. Therefore, in this embodiment, a layer 4 (refractive index n _B ; n _B > n _C ) having a higher refractive index than that of the substrate 2 is formed between the anode 8 and the substrate 2, and conditions for total reflection occurring at the electrode interface To ease. In the case of this embodiment, the planarization insulating film 4 has a configuration in which about 5 wt% of inorganic fine particles 3 of ZrO ₂ (zirconium oxide) are contained in the acrylic resin 4A (refractive index: 1.43). The average refractive index n _B including the resin 4A and the fine particles 3 is adjusted to 1.8.

Note that a resin material other than an acrylic resin, such as an epoxy resin (refractive index: 1.42), can also be used for the insulating material 4A serving as a base material. In addition, when good flatness can be obtained, an inorganic insulating material such as SiO ₂ (silicon oxide) or SiN (silicon nitride) can be used. Moreover, as the fine particles 3, other high refractive index materials such as TiO ₂ (titanium oxide) can be used. The refractive index ratio n _B / n _A can be adjusted by the amount of fine particles 3 contained in the insulating material 4A.

In the organic EL device 100, the light emitted from the light emitting layer 5 is extracted directly from the anode 8 or reflected from the cathode 9 and indirectly from the substrate 2 side. Since the refractive index ratio n _B / n _A between the anode 8 and the planarization insulating film 4 is 92%, approximately 85% of light can be extracted to the planarization insulating film 4 side at these interfaces. In addition, since the uneven portion 2A is formed on the surface of the substrate 2, light that cannot be extracted outside after being totally reflected inside the planarization insulating film 4 can be externally removed by removing the total reflection condition due to the unevenness. Can be taken out. Furthermore, since the light is scattered by the fine particles 3, even if the light is incident on the planarization insulating film 4 at an angle greater than the critical angle, most of the light will be out of the total reflection condition at the point of incidence on the substrate 2. Further, the amount of light can be increased. By these actions, light extraction efficiency is improved, and bright display is possible.

  The light emission rate when the above configuration is adopted is 15 cd / A, and a higher light emission rate can be obtained compared to the conventional configuration (light emission rate: 10 cd / A) in which the high refractive index fine particles 3 are not mixed. Has been confirmed.

[Method for Manufacturing Organic EL Device]
Next, a method for manufacturing the organic EL device 100 will be described.
First, a translucent substrate 2 such as a glass substrate is prepared, and a large number of random irregularities having a height of 0.01 μm to 0.5 μm are formed on the surface of the substrate 2 by hydrofluoric acid treatment or the like. The unevenness can also be formed by a treatment other than the hydrofluoric acid treatment. Due to these irregularities, the irregularities 2 </ b> A are formed on the surface of the substrate 2.

Next, an insulating material mainly composed of acrylic resin 4A is applied to the surface of the substrate 2 to form a flattened insulating film 4 that flattens the uneven portion 2A. The acrylic resin 4A is premixed with about 5 wt% of ZrO ₂ fine particles 3 as a high refractive index material so that the average refractive index n _{B of} the planarization insulating film 4 is larger than the refractive index n _{C of the} substrate 2. Adjust to. At this time, it is desirable to adjust the refractive index ratio n _B / n _A to the anode 8 to be 0.8 or more, more preferably 1 or more. The refractive index ratio n _B / n _A can be adjusted by the mixing amount of the fine particles 3. As the fine particles 3, other high refractive index materials such as TiO ₂ can be used.

Next, a light-transmitting conductive film such as ITO is formed on the surface of the planarization insulating film 4 by sputtering or the like, and is patterned to form the anode 8.
Next, the hole transport layer 6, the light emitting layer 5, and the electron transport layer 7 are sequentially formed on the surface of the anode 8. These layers can be formed by a vapor deposition method, an inkjet method, or the like. When the ink jet method is used, it is desirable to previously form a bank structure called a bank around the anode 8 in order to prevent ink from spreading. An organic functional layer 11 is formed by the hole transport layer 6, the light emitting layer 5, and the electron transport layer 7.

Next, the cathode 9 made of Al or the like is formed on the surface of the organic functional layer 11 by sputtering or the like. In an active matrix type organic EL device using TFT, patterning of the cathode 9 is not necessary. Such a cathode 9 serves as a common electrode common to the anodes 8.
A sealing member can be provided on the surface of the cathode 9 as necessary. By sealing the entire cathode with the sealing member, it is possible to prevent moisture, oxygen, and the like from entering the organic EL element 10.
Thus, the organic EL device 100 is completed.

[Example]
In order to verify the effect of the present invention, the present inventor compared the brightness of display between the organic EL device having the conventional configuration (comparative example) and the organic EL device of the present invention (example). Table 1 shows that the refractive index n _A of the anode 8 is constant (refractive index n _A : 2.0) and the refractive index n _B of the planarization insulating film 4 is the same in the organic EL device having the same configuration as that of the above embodiment. The result of simulating the light extraction efficiency by changing is shown. In this simulation, the substrate 2 is a glass substrate (refractive index n _C : 1.54), and the base material of the planarization insulating film is an acrylic resin (refractive index: 1.43). Further, the organic EL device according to the example is configured such that ZrO ₂ is mixed as the high refractive index fine particles 3, and the high refractive index fine particles 3 are not mixed into the organic EL device according to the comparative example.

As can be seen from Table 1, when the refractive index ratio between the anode 8 and the planarization insulating film 4 is 0.8 or more, 60% or more of light can be extracted to the planarization insulating film 4 side. This efficiency is more than twice as high as that of the conventional configuration, and means that the lifetime is extended by more than three times when the same amount of light is output. In particular, when the average refractive index n _B of the planarization insulating film is adjusted to be equal to or higher than the refractive index n _{A of the} anode 8 (n _B ≧ n _A ), the light is Since the light is incident on the planarization insulating film 4 that is a high refractive index material from the anode 8 that is a low refractive index material, total reflection does not occur at the interface with the planarization insulating film 4. Therefore, all the light transmitted through the anode 8 is incident on the planarization insulating film 4 and the light extraction efficiency is 1.

  Thus, in the organic EL device of this embodiment, the planarization insulating film 4 is an insulating film having both a higher refractive index and light scattering than the substrate 2, and thus has a high light extraction efficiency. It will improve and bright display will be obtained.

[Second Embodiment]
FIG. 2 is a sectional view showing a schematic configuration of the organic EL device according to the second embodiment of the present invention.
The organic EL device 200 of this embodiment is a so-called top emission type organic EL device that extracts light (display light) emitted from the light emitting layer 5 from the side opposite to the substrate 2. The basic configuration of the organic EL device 200 is the same as that of the organic EL device 100 of the first embodiment. The difference is that the cathode 9 is a translucent conductive film, and a reflective film that reflects light emitted toward the substrate 2 side to the light emitting layer 5 side between the planarization insulating film 4 and the substrate 2. The only difference is that 12 is provided. For this reason, the same code | symbol is attached | subjected about the component similar to 1st Embodiment, and detailed description is abbreviate | omitted.

  In this embodiment, since the display light is extracted from the cathode 9 side, a light-transmitting conductive film such as ITO is used for the cathode 9. Regarding the anode 8, since the reflective film 12 is provided on the substrate 2 side, a translucent conductive film such as ITO is used as in the first embodiment. As the substrate 2, in addition to a transparent substrate such as glass, an opaque substrate can also be used. Examples of opaque substrates include ceramics such as alumina, metal sheets such as stainless steel that have been subjected to insulation treatment such as surface oxidation, thermosetting resins and thermoplastic resins, and films thereof (plastic films). It is done.

The surface of the substrate 2 is provided with an uneven portion 2A in which a lot of random unevenness is formed, and the planarizing insulating film 4 is provided on the surface of the uneven portion 2A. As in the first embodiment, the planarization insulating film 4 has a configuration in which fine particles 3 having a refractive index larger than this are included in an insulating material 4A as a base material. In the case of the present embodiment, the planarization insulating film 4 has a configuration in which 3 wt% of TiO ₂ inorganic fine particles 3 are contained in the epoxy resin 4A, and an average refractive index n including the resin 4A and the fine particles 3 is included. _B is adjusted to 1.8. As the anode 8, an ITO film having a refractive index n _A of 2.0 is used, and a refractive index ratio n _B / n _A between the anode 8 and the planarization insulating film 4 is 0.9. The material of the insulating material 4A and the fine particles 3 can be changed as appropriate.

  A reflective film 12 made of Al (aluminum), Ag (silver), or the like is provided between the planarization insulating film 4 and the substrate 2. The reflective film 12 constitutes a reflective surface that reflects light emitted from the light emitting layer 5 to the substrate 2 side to the cathode 9 side. When the substrate 2 itself has light reflectivity, for example, when the substrate 2 is made of an aluminum substrate or the like, the light reflecting film 12 can be omitted. In this case, the board | substrate 2 itself comprises a reflective surface.

In this organic EL device 200, the light emitted from the light emitting layer 5 to the substrate 2 side passes through the anode 8 and the planarization insulating film 4, reaches the reflection film 12, and is reflected by the reflection film 12. It is taken out from the cathode 9 side. Since the refractive index ratio n _B / n _A between the anode 8 and the planarization insulating film 4 is 90%, approximately 80% of light can be extracted to the planarization insulating film 4 side at these interfaces. In addition, since the uneven portion 2A is formed on the surface of the substrate 2, light that cannot be extracted outside after being totally reflected inside the planarization insulating film 4 can be externally removed by removing the total reflection condition due to the unevenness. Can be taken out. Furthermore, since the light is scattered by the fine particles 3, even if the light is incident on the planarization insulating film 4 at an angle greater than the critical angle, most of the light will be out of the total reflection condition at the point of incidence on the substrate 2. Further, the amount of light can be increased. By these actions, light extraction efficiency is improved, and bright display is possible.

The light emission rate when the above configuration is adopted is 13 cd / A, and a higher light emission rate can be obtained compared to the conventional configuration (light emission rate: 8 cd / A) in which the high refractive index fine particles 3 are not mixed. Has been confirmed.
In the present embodiment, n _B <n _A , but it is preferable that n _B ≧ n _A in order to further increase the extraction efficiency.

[Third Embodiment]
FIG. 3 is a cross-sectional view showing a schematic configuration of an organic EL device according to a third embodiment of the present invention.
The organic EL device 300 of this embodiment is a so-called top emission type organic EL device that extracts light (display light) emitted from the light emitting layer 5 from the side opposite to the substrate 2. In this organic EL device 300, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The organic EL device 300 has a configuration in which the organic EL element 10 is disposed on the upper surface of the substrate 2. The organic EL element 10 includes a first electrode 8, a hole transport layer 6, a light emitting layer 5, an electron transport layer 7, and a second electrode 9 on one side (upper surface in FIG. 1) side of the substrate 2. It is the structure laminated | stacked in order. In the present embodiment, the first electrode 8 is an anode and the second electrode 9 is a cathode, but these can be reversed. In this case, a structure in which a cathode, an electron transport layer, a light emitting layer, a hole transport layer, and an anode are sequentially laminated from the substrate 2 side is obtained. The hole transport layer 6, the light emitting layer 5, and the electron transport layer 7 form an organic functional layer 11 made of an organic functional material.

  In the present embodiment, since the display light is extracted from the cathode 9 side, a light-transmitting conductive film such as ITO is used for the cathode 9. On the other hand, a conductive film having good light reflectivity, for example, a highly reflective metal film such as Al can be suitably used for the anode 8. In this case, the anode 8 has a function of reflecting light generated in the light emitting layer 5 to the cathode 9 side. In addition to Al, Au (gold), Ag (silver), Cr (chromium), Cu (copper), Ni (nickel), Ca, Mg (magnesium), Sr, Yb (ytterbium), Er (erbium) ), Tb (terbium), Sm (samarium), and the like, and a structure in which a plurality of thin films of metal materials selected from these are stacked.

As the substrate 2, in addition to a transparent substrate such as glass, an opaque substrate can also be used. Examples of opaque substrates include ceramics such as alumina, metal sheets such as stainless steel that have been subjected to insulation treatment such as surface oxidation, thermosetting resins and thermoplastic resins, and films thereof (plastic films). The light emitting layer 5, the hole transport layer 6, and the electron transport layer 7 are the same as in the first embodiment.

  A substrate 13 is bonded to the surface of the cathode 9 through an adhesive layer 40. The adhesive layer 40 is solidly formed over the entire display area, and the organic EL element 10 is sealed by the adhesive layer 40 and the substrate 13.

  An uneven portion 13A is provided on the surface of the substrate 13 where the cathode 9 is disposed. The uneven portion 13 </ b> A is provided to prevent total reflection at the interface between the adhesive layer 40 and the substrate 13. When the uneven portion 13A exists in this way, the total reflection condition at the interface between the substrate 13 and the adhesive layer 40 is relaxed, so that almost all the light incident on the adhesive layer 40 is extracted from the substrate 13 side. become. The adhesive layer 40 fills the uneven portion 13A and planarizes the surface of the substrate 13, and functions as a planarization insulating film of the present invention.

The adhesive layer 40 includes fine particles 30 having a refractive index greater than that of the insulating material 40A as a base material at least at the interface with the cathode 9, and adhesion of the interface portion including the fine particles 30 is performed. The average refractive index n _B of the layer 40 is adjusted to be larger than the refractive index n _C of the substrate 13. In the case of this embodiment, the adhesive layer 40 has a configuration in which about 5 wt% of ZrO ₂ fine particles 30 are contained in the acrylic resin 40A, and the average refractive index n _B including the acrylic resin 40A and the fine particles 30 is included. Has been adjusted to 1.8. As the cathode 9, an ITO film having a refractive index n _A of 2.0 is used, and the refractive index ratio n _B / n _A between the cathode 9 and the adhesive layer 40 is 0.9.

Note that a resin material other than an acrylic resin, such as an epoxy resin, can also be used for the insulating material 40A as a base material. In addition, when good flatness can be obtained, an inorganic insulating material such as SiO ₂ or SiN can be used. As the fine particles 30, other high refractive index materials such as TiO ₂ can be used. The refractive index ratio n _B / n _A can be adjusted by the amount of fine particles 30 contained in the insulating material 40A.

In this organic EL device 300, the light emitted from the light emitting layer 5 is extracted directly from the cathode 9 or reflected by the anode 8 and indirectly from the substrate 13 side. Since the refractive index ratio n _B / n _A between the cathode 9 and the adhesive layer 40 is 90%, approximately 80% of light can be extracted to the adhesive layer 40 side at these interfaces. Further, since the uneven portion 13A is formed on the surface of the substrate 13, light that is totally reflected inside the adhesive layer 40 and cannot be extracted outside is extracted outside by removing the total reflection condition due to the unevenness. Will be able to. Furthermore, since the light is scattered by the fine particles 30, even if the light is incident on the adhesive layer 40 at an angle greater than the critical angle, most of the light is incident on the substrate 13 and is out of the total reflection condition. Can be increased. By these actions, light extraction efficiency is improved, and bright display is possible.

  The light emission rate when the above configuration is adopted is 14.5 cd / A, and a higher light emission rate is obtained compared to the conventional configuration (light emission rate: 9 cd / A) in which the high refractive index fine particles 30 are not mixed. It has been confirmed that

[Method for Manufacturing Organic EL Device]
Next, a method for manufacturing the organic EL device 300 will be described.
First, a translucent substrate 13 such as a glass substrate is prepared, and a large number of random irregularities having a height of 0.01 μm to 0.5 μm are formed on the surface of the substrate 13 by hydrofluoric acid treatment or the like. The unevenness can also be formed by a treatment other than the hydrofluoric acid treatment. Due to these irregularities, an irregular portion 13 </ b> A is formed on the surface of the substrate 13.

  Next, an insulating material mainly composed of acrylic resin 40A is applied to the surface of the substrate 2 and bonded to the substrate 2 on which the organic EL element 10 is formed. The organic EL element 10 can be formed by the same procedure as in the first embodiment. However, since the cathode 9 must have a light transmitting property, it is formed of a light transmitting conductive material such as ITO.

The adhesive layer 40 is applied to at least the entire surface of the display area where the organic EL element 10 is disposed. The acrylic resin 40A is mixed in advance with about 5 wt% of ZrO ₂ fine particles 30 as a high refractive index material, and adjusted so that the average refractive index n _B of the adhesive layer 40 is larger than the refractive index n _{C of the} substrate 13. Keep it. At this time, it is desirable to adjust the refractive index ratio n _B / n _A to the cathode 9 to be 0.8 or more, more preferably 1 or more. The refractive index ratio n _B / n _A can be adjusted by the mixing amount of the fine particles 30. As the fine particles 30, other high refractive index materials such as TiO ₂ can be used.

Since the adhesive layer 40 has high fluidity, the adhesive layer 40 is disposed in the unevenness without any gap so as to fill the uneven portion 13 </ b> A of the substrate 13. Moreover, in the process of adhesion, it spreads over the entire surface of the cathode 9 and the surface on the cathode 9 side is flattened. After the adhesive layer 40 and the substrate 12 are disposed on the cathode 9, the adhesive layer 40 is cured by heat curing or ultraviolet curing.
As described above, the organic EL element 10 is sealed by the substrate 13, and the organic EL device 300 is completed.

[Fourth Embodiment]
FIG. 4 is a cross-sectional view showing a schematic configuration of an organic EL device according to a fourth embodiment of the present invention.
The organic EL device 400 according to the present embodiment is a so-called top emission type organic EL device that extracts light (display light) emitted from the light emitting layer 5 from the side opposite to the substrate 2. The basic configuration of the organic EL device 500 is the same as that of the organic EL device 300 of the third embodiment. The only difference is that the color filter layer 14 is provided between the substrate 13 and the adhesive layer 40. For this reason, the same code | symbol is attached | subjected about the component similar to 3rd Embodiment, and detailed description is abbreviate | omitted.

In the case of the present embodiment, the color filter layer 14 and the adhesive layer 40 are interposed between the substrate 13 and the cathode 9, and these together form the planarization insulating film of the present invention. In FIG. 4, the uneven portion 13 </ b> A of the substrate 13 is flattened only by the color filter layer 14, but the uneven portion 13 </ b> A may be flattened by both the color filter layer 14 and the adhesive layer 40.
The adhesive layer 40 is formed as a solid over the entire display area, and the organic EL element 10 is sealed by the adhesive layer 40 and the substrate 13 including the color filter layer 14.

The adhesive layer 40 includes fine particles 30 having a refractive index larger than that of the insulating material 40A serving as a base material at least at the interface with the cathode 9, and the average of the planarized insulating film including the fine particles 30 is included. The refractive index is adjusted to be larger than the refractive index of the substrate 13 (refractive index n _C : 1.54). In the case of this embodiment, the adhesive layer 40 has a configuration in which about 7 wt% of ZrO ₂ fine particles 30 are contained in the acrylic resin 40A, and the average refractive index n _B including the acrylic resin 40A and the fine particles 30 is included. Is adjusted to 1.85. As the cathode 9, an ITO film having a refractive index n _A of 2.0 is used, and the refractive index ratio n _B / n _A between the cathode 9 and the adhesive layer 40 is 0.92. The average refractive index n _D of the color filter layer 14 is 1.81, and the refractive index ratio n _D / n _B with the adhesive layer 40 is 97%. The materials of the insulating material 40A and the fine particles 30 can be changed as appropriate.

  The color filter layer 14 has a structure in which pigment molecules, which are coloring materials, are dispersed in an insulating material such as an acrylic resin, which is a base material, and the basic structure is the same as that of the adhesive layer 40. . For this reason, the coloring material of the color filter layer 14 and the material of the fine particles 30 of the adhesive layer 40 are made common, and the insulating material of the color filter layer 14 and the insulating material 40A of the adhesive layer 40 are made common, thereby It can be formed integrally. In this case, the color filter layer is formed by a plurality of layers each having a coloring function and an adhesion function.

In the organic EL device 400, the light emitted from the light emitting layer 5 is extracted directly from the cathode 9 or reflected by the anode 8 and indirectly from the substrate 13 side. Since the refractive index ratio n _B / n _A between the cathode 9 and the adhesive layer 40 is 92%, approximately 85% of light can be extracted to the adhesive layer 40 side at these interfaces. Further, since the refractive index ratio n _D / n _B between the adhesive layer 40 and the color filter layer 14 is 97%, 90% or more of light can be extracted to the color filter layer 14 side at these interfaces. In addition, since the uneven portion 13A is formed on the surface of the substrate 13, light that cannot be extracted to the outside after being totally reflected inside the color filter layer 14 is exposed to the outside by removing the total reflection condition due to the unevenness. It can be taken out. Furthermore, since the light is scattered by the fine particles 30, even if the light is incident on the adhesive layer 40 at an angle greater than the critical angle, many of them are out of the total reflection condition at the time of entering the color filter layer 14, Further, the amount of light can be increased. By these actions, light extraction efficiency is improved, and bright display is possible.

When the above configuration is adopted, the light emission rate is 8.1 cd / A, which is higher than the conventional configuration (light emission rate: 5 cd / A) in which the high refractive index fine particles 30 are not mixed. It has been confirmed that
In this embodiment, n _D <n _B <n _A , but it is preferable that n _D ≧ n _B ≧ n _A in order to further increase the extraction efficiency.

[Fifth Embodiment]
FIG. 5 is a cross-sectional view showing a schematic configuration of an organic EL device according to a fifth embodiment of the present invention.
The organic EL device 500 of the present embodiment is a so-called top emission type organic EL device that extracts light (display light) emitted from the light emitting layer 5 from the side opposite to the substrate 2. The basic configuration of the organic EL device 500 is the same as that of the organic EL device 400 of the fourth embodiment. The only difference is that the overcoat layer 15 is provided between the color filter layer 14 and the adhesive layer 40. For this reason, the same code | symbol is attached | subjected about the component similar to 4th Embodiment, and detailed description is abbreviate | omitted.

In the case of this embodiment, the color filter layer 14, the overcoat layer 15, and the adhesive layer 40 are interposed between the substrate 13 and the cathode 9, and these are integrated to form the planarization insulating film of the present invention. Configure. In FIG. 5, the uneven portion 13A of the substrate 13 is flattened only by the color filter layer 14, but the uneven portion 13A is formed by two layers of the color filter layer 14 and the overcoat layer 15, or the color filter layer 14 to the adhesive layer. Planarization may be performed with up to 40 three layers.
The adhesive layer 40 is solid over the entire display area, and the organic EL element 10 is sealed by the adhesive layer 40 and the substrate 13 including the overcoat layer 15 and the color filter layer 14.

The adhesive layer 40 includes fine particles 30 having a refractive index larger than that of the insulating material 40A serving as a base material at least at the interface with the cathode 9, and the average of the planarized insulating film including the fine particles 30 is included. The refractive index is adjusted to be larger than the refractive index of the substrate 13 (refractive index n _C : 1.54). In the case of this embodiment, the adhesive layer 40 has a configuration in which about 7 wt% of ZrO ₂ fine particles 30 are contained in the acrylic resin 40A, and the average refractive index n _B including the acrylic resin 40A and the fine particles 30 is included. Is adjusted to 1.85. As the cathode 9, an ITO film having a refractive index n _A of 2.0 is used, and the refractive index ratio n _B / n _A between the cathode 9 and the adhesive layer 40 is 0.92. The refractive index n _E of the overcoat layer 15 is the same as the refractive index n _B of the adhesive layer 40, and the refractive index ratio n _E / n _B is 1. The average refractive index n _D of the color filter layer 14 is 1.81, and the refractive index ratio n _D / n _E with the overcoat layer 15 is 97%. The materials of the insulating material 40A and the fine particles 30 can be changed as appropriate.

  The color filter layer 14 has a structure in which pigment molecules, which are coloring materials, are dispersed in an insulating material such as an acrylic resin, which is a base material, and the basic structure is the same as that of the adhesive layer 40. . For this reason, the coloring material of the color filter layer 14 and the material of the fine particles 30 of the adhesive layer 40 are made common, and the insulating material of the color filter layer 14 and the insulating material 40A of the adhesive layer 40 are made common, thereby It can be formed integrally. Further, if the overcoat layer 15 is formed of the same base material as that of the color filter layer 14, three layers from the color filter layer 14 to the adhesive layer 40 can be integrally formed. In these cases, the color filter layer is formed by a plurality of layers each having a coloring function, a function as an overcoat, and an adhesion function.

In the organic EL device 500, the light emitted from the light emitting layer 5 is extracted directly from the cathode 9 or reflected by the anode 8 and indirectly from the substrate 13 side. Since the refractive index ratio n _B / n _A between the cathode 9 and the adhesive layer 40 is 92%, approximately 85% of light can be extracted to the adhesive layer 40 side at these interfaces. The adhesive layer 40 and the overcoat layer 15 have the same refractive index, and the refractive index ratio n _D / n _E with the color filter layer 14 is 97%. It can be taken out to the filter layer 14 side. In addition, since the uneven portion 13A is formed on the surface of the substrate 13, light that cannot be extracted to the outside after being totally reflected inside the color filter layer 14 is exposed to the outside by removing the total reflection condition due to the unevenness. It can be taken out. Furthermore, since the light is scattered by the fine particles 30, even if the light is incident on the adhesive layer 40 at an angle greater than the critical angle, many of them are out of the total reflection condition at the time of entering the color filter layer 14, Further, the amount of light can be increased. By these actions, light extraction efficiency is improved, and bright display is possible.

When the above configuration is adopted, the light emission rate is 8.1 cd / A, which is higher than the conventional configuration (light emission rate: 5 cd / A) in which the high refractive index fine particles 30 are not mixed. It has been confirmed that
In this embodiment, n _D <n _E = n _B <n _A , but it is preferable that n _D ≧ n _E ≧ n _B ≧ n _A in order to further increase the extraction efficiency.

[Electronics]
Examples of electronic devices provided with the organic EL device of the above embodiment will be described.
FIG. 6 is a perspective view showing an example of a mobile phone. A cellular phone 1300 shown in the figure includes a plurality of operation buttons 1302, an earpiece 1303, a mouthpiece 1304, and a display unit 1301 including the organic EL device of the previous embodiment. According to the mobile phone 1300, since the organic EL device according to the above-described embodiment is provided, it is possible to realize an electronic apparatus that has an organic EL display unit with a high display quality and a bright screen.
The electronic apparatus provided with the organic EL device according to the present invention is not limited to the above-mentioned ones. For example, digital cameras, personal computers, televisions, portable televisions, viewfinder type / monitor direct view type video tape recorders. PDAs, portable game machines, pagers, electronic notebooks, calculators, clocks, word processors, workstations, videophones, POS terminals, devices with touch panels, and the like. In addition, examples of the electronic device including the organic EL device according to the present invention include a vehicle-mounted display such as a vehicle-mounted audio device, a vehicle instrument, and a car navigation device. Furthermore, the organic EL device can be widely applied to electronic devices other than display devices such as exposure means of line printers.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention. In addition, the configuration of the above-described embodiment is an example, and these configurations can be combined as necessary. For example, by combining the configuration of the second embodiment and the configurations of the third to fifth embodiments, the light extraction efficiency from both the anode 8 and the cathode 9 can be improved, and a brighter display can be realized. Become. In the above embodiment, an organic EL device using an organic light emitting material for the light emitting layer has been described as an example. However, the present invention can also be applied to an inorganic EL device using an inorganic material for the light emitting layer. .

1 is a cross-sectional view illustrating a schematic configuration of an organic EL device according to a first embodiment. It is sectional drawing which shows schematic structure of the organic EL apparatus which concerns on 2nd Embodiment. It is sectional drawing which shows schematic structure of the organic EL apparatus which concerns on 3rd Embodiment. It is sectional drawing which shows schematic structure of the organic EL apparatus which concerns on 4th Embodiment. It is sectional drawing which shows schematic structure of the organic EL apparatus which concerns on 5th Embodiment. It is a perspective view which shows an example of the electronic device provided with the said organic EL apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Board | substrate, 2A ... Uneven part, 3 ... Fine particle, 4 ... Flattening insulating film, 4A ... Insulating material, 5 ... Light emitting layer, 8 ... Anode (1st electrode), 9 ... Cathode (2nd electrode), 12 ... Reflective film, 13 ... substrate, 13A ... uneven portion, 14 ... color filter layer, 30 ... fine particles, 40 ... adhesive layer, 40A ... insulating material, 1300 ... mobile phone (electronic device)

Claims (14)

A pair of electrodes for holding the light emitting layer;
A substrate on which one of the pair of electrodes is disposed;
An uneven portion provided on the surface of the substrate on which the one electrode is disposed;
A planarization insulating film that is interposed between the one electrode and the substrate and planarizes the uneven portion;
The planarization insulating film includes fine particles having a refractive index larger than that of the insulating material as a base material, and an average refractive index of the planarization insulating film containing the fine particles is larger than a refractive index of the substrate. The electroluminescence device is adjusted so as to be large.   The electroluminescent device according to claim 1, wherein the fine particles have a refractive index larger than that of the one electrode.   The average refractive index of the planarization insulating film in the portion containing the fine particles is adjusted to be equal to or higher than the refractive index of the one electrode. Item 3. The electroluminescent device according to Item 2.   The electroluminescent device according to claim 1, wherein the one electrode is an electrode on a side from which display light is emitted.   The electroluminescent device according to claim 4, wherein the one electrode is formed on a surface of the planarization insulating film.   The electroluminescent device according to claim 4, wherein the planarization insulating film includes an adhesive layer, and the one electrode and the substrate are bonded via the adhesive layer.   The electroluminescent device according to claim 6, wherein the fine particles are contained in the adhesive layer.   7. The electroluminescence device according to claim 5, wherein the planarization insulating film includes a color filter layer, and the fine particles are included in the color filter layer.   9. The electroluminescence device according to claim 8, wherein the fine particles also serve as a coloring material for the color filter layer.   The one electrode is an electrode opposite to a side from which display light is emitted, and light emitted toward the substrate side is disposed between the planarization insulating film and the substrate in the light emitting layer. The electroluminescent device according to any one of claims 1 to 3, wherein a reflective surface that reflects toward the side is provided. A method of manufacturing an electroluminescence device comprising a pair of electrodes for holding a light emitting layer and a substrate on which one of the pair of electrodes is disposed,
Forming an uneven portion on the substrate;
Forming a planarization insulating film on the surface of the concavo-convex portion to flatten the concavo-convex portion;
Arranging the one electrode on the surface of the planarization insulating film,
In the step of forming the planarization insulating film, the insulating material serving as a base material contains fine particles having a refractive index larger than that of the insulating material, and the average refractive index of the flattening insulating film containing the base material and the fine particles is included. Includes a step of adjusting the refractive index to be larger than the refractive index of the substrate.   12. The method of manufacturing an electroluminescent device according to claim 11, wherein the fine particles are made of a material having a refractive index larger than that of the one electrode.   13. The method of manufacturing an electroluminescent device according to claim 12, wherein an average refractive index of the planarization insulating film is adjusted to be higher than a refractive index of the one electrode. An electronic apparatus comprising the electroluminescence device according to any one of claims 1 to 10 or the electroluminescence device produced by the production method according to any one of claims 11 to 13. .

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