WO2012121287A1

WO2012121287A1 - Phosphor substrate and display device

Info

Publication number: WO2012121287A1
Application number: PCT/JP2012/055814
Authority: WO
Inventors: 勇毅小林; 悦昌藤田; 別所　久徳; 大江　昌人
Original assignee: シャープ株式会社
Priority date: 2011-03-10
Filing date: 2012-03-07
Publication date: 2012-09-13

Abstract

This phosphor substrate is provided with a phosphor layer, a first layer, and a second layer. The phosphor layer has an excitation-light-incidence surface and a phosphorescent-light-extraction surface. Excitation light that enters through the excitation-light-incidence surface generates phosphorescent light, and the phosphorescent light is emitted. The first layer contacts the excitation-light-incidence surface. The second layer contacts the phosphorescent-light-extraction surface. The phosphor layer is configured such that a refractive index (na) in the vicinity of the excitation-light-incidence surface is smaller than a refractive index (n1) of the first layer. The phosphor layer is configured to have a refractive index distribution between the excitation-light-incidence surface and the phosphorescent-light-extraction surface such that the absolute value (│n1-na│) of the difference between the phosphor layer refractive index (na) in the vicinity of the excitation-light-incidence surface and the refractive index (n1) of the first layer is smaller than the absolute value (│n1-nb│) of the difference between a refractive index (nb) of the phosphor layer in the vicinity of the phosphorescent-light-extraction surface and the refractive index (n1) of the first layer.

Description

Phosphor substrate and display device

The present invention relates to a phosphor substrate and a display device.
This application claims priority on March 10, 2011 based on Japanese Patent Application No. 2011-053425 for which it applied to Japan, and uses the content here.

In recent years, the need for a thin flat panel display (FPD) display device is increasing as an alternative to a display device using a cathode ray tube, which has been the mainstream in the past. There are various types of FPD, for example, non-self-luminous liquid crystal display (LCD), self-luminous plasma display panel (PDP), inorganic electroluminescence (inorganic EL) display, or organic electroluminescence (organic EL). A display or the like is known.

In particular, organic EL displays are actively researched and developed because the elements used for display (organic EL elements) are thin and lightweight, and have characteristics such as low voltage drive, high luminance, and self-luminous emission. Has been done. Recently, application of organic EL elements to light sources such as electrophotographic copying machines or printers, light emitting devices, and the like is expected. When an organic EL element is used in a light emitting device, the organic EL element has surface emission, has high color rendering properties, and has an advantage that light control is easy. Furthermore, fluorescent lamps contain mercury, but organic EL elements do not contain mercury, or light emission from organic EL elements has many advantages such as no ultraviolet rays.
In such an organic EL display, a technique for performing moving picture display by simple matrix driving, and a technique for performing moving picture display by active matrix driving of organic EL elements using a thin film transistor (TFT) as a driving element are known. .

Further, in a conventional display, full-color display is performed by arranging pixels emitting red, green, and blue as one unit to create various colors typified by white.
In order to realize this, in the case of organic EL, a method of forming each pixel of red, green, and blue by generally coating the organic light emitting layer by mask vapor deposition using a shadow mask is adopted. . However, this method requires improvement in mask processing accuracy, mask and substrate alignment accuracy, and mask size enlargement. In particular, in the field of large displays typified by television (TV), the substrate size has increased from the so-called G6 generation (1800 mm × 1500 mm) to G8 generation (2460 mm × 2160 mm) and G10 generation (3050 mm × 2850 mm). It is out. Therefore, since the conventional method requires a mask equivalent to or larger than the substrate size, it is necessary to manufacture and process a mask corresponding to a large substrate.

Since the mask is made of a very thin metal (general film thickness: 50 nm to 100 nm), it is difficult to increase the size of the mask. That is, it is difficult to manufacture and process a mask corresponding to a large substrate. When the mask processing accuracy and the mask alignment accuracy are lowered, color mixing due to mixing of the light emitting layers occurs.
In order to prevent these phenomena, it is necessary to increase the width of the insulating layer provided between the pixels. However, when the area of the pixels is determined, the area of the light emitting portion is reduced. That is, it leads to a decrease in the aperture ratio of the pixel, leading to a decrease in luminance of the organic EL element, an increase in power consumption, and a decrease in life.

In the conventional manufacturing method, the deposition source is disposed below the substrate, and the organic material is deposited from the bottom to the top, thereby forming an organic layer. Along with this, the mask is bent at the center, which causes the color mixture. In an extreme case, a portion where the organic layer is not formed is formed, which causes leakage of the upper and lower electrodes. In the conventional method, if the mask is used a predetermined number of times, it cannot be used due to deterioration. Therefore, an increase in the size of the mask leads to a manufacturing cost of the display, which leads to an increase in cost.

Therefore, an organic EL portion having a light emitting layer that emits light in a blue region to blue-green region, and a phosphor layer that emits green light by absorbing light emitted from the blue region to blue-green region from the organic EL portion as excitation light. A method of emitting full color by combining a green pixel composed of a red pixel composed of a phosphor layer that emits red light and a blue pixel composed of a blue color filter for the purpose of improving color purity has been proposed ( See Patent Document 1 below). This method is superior to the above-described coating method in that it does not require patterning of the organic layer, can be easily manufactured, and is superior in cost.

However, due to the refractive index difference at the excitation light incident side interface of the phosphor layer, a part of the excitation light is totally reflected and not absorbed by the phosphor layer, resulting in a phenomenon that the amount of fluorescence generated is reduced. Occurs and the resulting luminous efficiency is reduced. Moreover, due to the difference in refractive index at the light extraction side interface of the phosphor layer, the light emitted from the phosphor layer is totally reflected at the interface, resulting in a phenomenon that the light extraction efficiency from the phosphor layer is lowered. Occurs and the resulting luminous efficiency is reduced. Such a decrease in luminous efficiency leads to an increase in power consumption of the display and display device.

In order to solve such a phenomenon, the refractive index difference between the member constituting the excitation light source and the member constituting the color conversion layer (phosphor layer) or between the member constituting the color conversion layer and the support substrate. There has been proposed a method of forming a protective layer having a function of reducing the thickness (see Patent Document 2 below).
A self-luminous liquid crystal display device combining a conventional liquid crystal display device and a phosphor has also been proposed. This is different from the conventional liquid crystal display device, because the RGB phosphor layer provided outside the liquid crystal layer emits light, so that it is possible to realize a display device with excellent viewing angle characteristics (patent) Document 3, Non-Patent Document 1).

Japanese Patent No. 2795932 JP 2003-133062 A JP 2000-131683 A

However, the method proposed in Patent Document 2 is effective only at one of the excitation light incident side interface and the light extraction side interface of the phosphor layer, so that the effect of reducing power consumption is small. In addition, there is a concern that the yield may decrease due to an increase in the number of steps for forming the protective layer.
Further, in the liquid crystal display devices proposed in Patent Document 3 and Non-Patent Document 1, it is caused by the refractive index difference at the excitation light incident side interface or the refractive index difference at the light extraction side interface of the phosphor layer described above. The emission efficiency and power consumption may still increase.

The aspect of the present invention has been made in view of such a background, and the amount of fluorescence generated in the phosphor layer is increased by efficiently causing excitation light to enter the phosphor layer, and further the fluorescence generated in the phosphor layer. An object of the present invention is to provide a phosphor substrate having improved luminous efficiency by improving the conversion efficiency by improving the efficiency of extracting the components to the outside of the substrate. Combined with organic EL elements and liquid crystal elements, etc., it has excellent viewing angle characteristics (a good image can be obtained with no deviation in color purity and brightness regardless of the viewing angle), and costs and power consumption are reduced. It is an object of the present invention to provide a display device that can perform the above-described operation.

In order to solve the above problems, the inventors focused on the refractive index at the excitation light incident side interface of the phosphor layer and the refractive index at the fluorescence extraction side interface of the phosphor layer, and as a result of earnest studies, Realized a method capable of achieving both the efficient incidence of excitation light to the phosphor layer and the high light extraction efficiency from the phosphor layer to the outside of the substrate, and the idea that the above problem can be solved, Several embodiments of the present invention have been completed.

That is, the phosphor substrate in one embodiment of the present invention includes a phosphor layer, a first layer, and a second layer. The phosphor layer has an excitation light incident surface and a fluorescence extraction surface, and emits fluorescence by generating fluorescence by excitation light incident through the excitation light incident surface. The first layer is in contact with the front excitation light incident surface. The second layer is in contact with the fluorescence extraction surface. The phosphor layer is configured such that the refractive index na in the vicinity of the excitation light incident surface is smaller than the refractive index n1 of the first layer. In the phosphor layer, the absolute value | n1-na | of the difference between the refractive index na in the vicinity of the excitation light incident surface and the refractive index n1 of the first layer is different from the refractive index nb in the vicinity of the fluorescence extraction surface. A refractive index distribution is formed between the excitation light incident surface and the fluorescence extraction surface so as to be smaller than the absolute value | n1-nb | of the difference in the refractive index n1 of one layer.

In the phosphor substrate according to one aspect of the present invention, the phosphor layer is configured such that a refractive index nb in the vicinity of the fluorescence extraction surface is larger than a refractive index n2 of the second layer, and the phosphor layer includes: The absolute value | n2-nb | of the difference between the refractive index nb of the phosphor layer near the fluorescence extraction surface and the refractive index n2 of the second layer is the refraction of the phosphor layer near the excitation light incident surface. And having a refractive index distribution between the excitation light incident surface and the fluorescence extraction surface so as to be smaller than the absolute value | n2-na | of the difference between the refractive index na and the refractive index n2 of the second layer. May be.

The phosphor substrate in one embodiment of the present invention includes a phosphor layer, a first layer, and a second layer. The phosphor layer has an excitation light incident surface and a fluorescence extraction surface. The phosphor layer generates fluorescence by excitation light incident through the excitation light incident surface and emits light. The first layer is in contact with the excitation light incident surface. The second layer is in contact with the fluorescence extraction surface. The phosphor layer is configured such that the refractive index nb in the vicinity of the fluorescence extraction surface is larger than the refractive index n2 of the second layer. The phosphor layer has an absolute value | n2-nb | of the difference between the refractive index nb of the phosphor layer and the refractive index n2 of the second layer in the vicinity of the fluorescence extraction surface, in the vicinity of the excitation light incident surface. Refractive index distribution between the excitation light incident surface and the fluorescence extraction surface so as to be smaller than the absolute value | n2-na | of the difference between the refractive index na of the phosphor layer and the refractive index n2 of the second layer. It is comprised.

Thus, by providing the phosphor layer of the phosphor substrate with a refractive index distribution, the excitation light can be converted into the phosphor layer by the refractive index difference at the excitation light incident side interface of the phosphor layer without adding another layer. It is possible to reduce a component (for example, a total reflection component) that is reflected and lost without being absorbed by the phosphor, and to increase the amount of fluorescence generated in the phosphor layer. And / or the component that reflects and loses the fluorescence without being extracted to the outside due to the difference in the refractive index at the fluorescence extraction side interface of the phosphor layer (for example, total reflection component) is reduced to efficiently emit light from the phosphor layer. It can be taken out.

Preferably, in the phosphor substrate according to one aspect of the present invention, the difference between the refractive index na of the phosphor layer in the vicinity of the excitation light incident surface and the refractive index n1 of the first layer in the vicinity of the excitation light incident surface. The absolute value | n1-na | is preferably 0.41 or less, and more preferably less than 0.1. The absolute value | n2-nb | of the difference between the refractive index nb in the vicinity of the fluorescence extraction surface of the phosphor layer and the refractive index n2 of the second layer in the vicinity of the fluorescence extraction surface is 0.41 or less. It is preferable that it is, and more preferably, it is less than 0.1. This is because when excitation light or fluorescence is isotropic light, more than half of the front light component is lost due to total reflection unless the refractive index difference is 0.41 or less according to Snell's law. Of course, the present invention is not limited to this when the excitation light or fluorescence is light having directivity in the front direction. Of course, the smaller the refractive index difference, the less total reflection loss.

Further, the refractive index distribution of the phosphor layer may continuously change from the excitation light incident surface toward the fluorescence extraction surface. Preferably, it is changed gently.
If the refractive index distribution of the phosphor layer is changed intermittently or exponentially, the refractive index change in the phosphor layer is large, and as a result, the fluorescence extraction efficiency from the phosphor layer may be reduced. Because there is. On the other hand, if the refractive index distribution of the phosphor layer changes continuously and smoothly, a difference in refractive index in the phosphor layer hardly occurs, and as a result, it is possible to improve the fluorescence extraction efficiency from the phosphor layer. Become.
The refractive index distribution does not need to increase or decrease uniformly from the excitation light incident surface of the phosphor layer toward the fluorescence extraction surface, and at least the difference in refractive index at the excitation light incident side interface of the phosphor layer. Alternatively, it is only necessary to distribute the refractive index difference at the fluorescence extraction side interface so as to be small. Preferably, the refractive index of the fluorescence extraction surface is smaller than the excitation light incident surface of the phosphor layer. More preferably, it decreases uniformly from the excitation light incident surface of the phosphor layer toward the fluorescence extraction surface. By making the refractive index distribution of the phosphor layer in this way, it becomes possible to take out the fluorescence to the outside more effectively.

The phosphor layer may contain an inorganic phosphor.
When directional excitation light is employed as the excitation light source, isotropic light emission is obtained by the scattering effect of the inorganic phosphor particles by causing the inorganic phosphor constituting the inorganic phosphor layer to emit light. Therefore, it is possible to provide a display device having excellent viewing angle characteristics.

The refractive index distribution of the phosphor layer may be adjusted by the dispersion concentration of the inorganic phosphor in the phosphor layer.
The phosphor layer is formed in a state where an inorganic phosphor having a high refractive index is dispersed in a binder material having a low refractive index. Therefore, if the dispersion concentration of the phosphor is lowered, the refractive index of the phosphor layer is decreased. Conversely, if the dispersion concentration is increased, the refractive index of the phosphor layer is increased. Therefore, by adjusting the dispersion concentration of the inorganic phosphor, it is possible to easily reduce the refractive index difference at the excitation light incident side interface and / or the fluorescence extraction side interface of the phosphor layer.

The refractive index distribution of the phosphor layer is preferably adjusted by the particle size distribution of the inorganic phosphor in the phosphor layer.
The smaller the particle size of the inorganic phosphor, the smaller the refractive index of the phosphor. Therefore, by adjusting the particle size distribution of the inorganic phosphor, the difference in refractive index between the excitation light incident side interface and / or the fluorescence extraction side interface of the phosphor layer can be easily reduced.
The adjustment of the dispersion concentration and the particle size distribution of the inorganic phosphor is not necessarily independent. By adjusting both the dispersion concentration and the particle size distribution, the excitation light incident side interface of the phosphor layer, and Alternatively, the difference in refractive index at the fluorescence extraction side interface may be reduced.

The phosphor layer may be formed by any one of a screen printing method, an ink jet method, a dispenser method, and a nozzle coating method.
By using the above method, the phosphor layer can be directly patterned. Therefore, the material utilization efficiency of the phosphor material is improved and the cost can be reduced as compared with the case where patterning is performed by the photolithography method. In addition, by using a water repellent treatment in combination with a wet process, the phosphor can be efficiently formed in a desired cross-sectional shape. This makes it possible to directly form a cross-sectional shape necessary for efficient light extraction.

A display device according to another aspect of the present invention includes the phosphor substrate and an excitation light source that emits the excitation light.
The excitation light source may be any of a light emitting diode, an organic electroluminescence element, and an inorganic electroluminescence element.
For example, when an organic electroluminescence element is used as an excitation light source, the display device has excellent viewing angle characteristics, low cost, and low power consumption.

The display device according to another aspect of the present invention further includes a plurality of driving elements, wherein the excitation light source includes a plurality of light emitting elements, and the plurality of light emitting elements are driven by the corresponding driving elements. Good.
Due to the active drive type, a display and a display device with excellent display quality are obtained. In addition, since the light emission time can be made longer than in passive driving, it is possible to reduce the driving voltage for obtaining desired luminance, and to reduce power consumption.

Furthermore, a display device according to another aspect of the present invention may have a substrate on which the drive element is formed. The phosphor layer is located between the second layer and the substrate, and light from the phosphor layer is emitted through the second layer. Thereby, it becomes possible to form with a high aperture ratio irrespective of a driving element or wiring made of TFT or the like. As a result, power consumption can be reduced.

Furthermore, the display device according to another aspect of the present invention may include a liquid crystal element that is provided between the excitation light source and the phosphor substrate and that can control a transmittance of light emitted from the excitation light source. Good. The excitation light source may be a planar light source that emits light from a light exit surface.
As a result, a display device with excellent display quality using a liquid crystal element as a switching element is obtained.

According to the aspect of the present invention, a phosphor substrate with improved luminous efficiency can be provided. In addition, it is possible to provide a display device capable of reducing cost and power consumption.

1 is a schematic cross-sectional view illustrating an entire display device according to a first embodiment. It is sectional drawing which shows the principal part of the light source side board | substrate of the display apparatus of 1st Embodiment. It is a schematic cross section of the 1st model of the conventional fluorescent substance substrate (display apparatus). It is a schematic cross section of the 2nd model of the conventional fluorescent substance substrate (display apparatus). It is a schematic cross section of the 3rd model of the conventional fluorescent substance substrate (display apparatus). It is a schematic cross section which shows the display apparatus of the 1st modification of 1st Embodiment. It is a schematic cross section which shows the display apparatus of the 2nd modification of 1st Embodiment. It is a schematic cross section which shows the whole display apparatus of the 3rd modification of 1st Embodiment. It is sectional drawing which shows the principal part of the light source side board | substrate of the display apparatus of the 3rd modification of 1st Embodiment. It is a schematic cross section which shows the whole display apparatus of the 4th modification of 1st Embodiment. It is sectional drawing which shows the principal part of the light source side board | substrate of the display apparatus of the 4th modification of 1st Embodiment. It is a schematic cross section which shows schematic structure of the display apparatus of 2nd Embodiment. It is a top view which shows the display apparatus of 2nd Embodiment. It is a schematic diagram of the voltage drive digital gradation system of an active matrix drive type organic EL element. It is a schematic cross section which shows schematic structure of the display apparatus of 3rd Embodiment. FIG. 11 is a schematic diagram illustrating an example of an electronic device including a display device according to an aspect of the invention. FIG. 11 is a schematic diagram illustrating an example of an electronic device including a display device according to an aspect of the invention. It is a side view for demonstrating a comparative example. It is a top view for demonstrating a comparative example. 1 is a side view for explaining Example 1. FIG. 6 is a plan view of the manufacturing process of Example 1. FIG. FIG. 6 is a side view for explaining Example 2; FIG. 10 is a plan view in the manufacturing process of Example 2. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 3. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. It is a sectional side view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. It is a top view which shows the process of the manufacturing method of the fluorescent substance substrate of Example 4. FIG. 10 is a side cross-sectional view showing a process of a method for manufacturing a light source side substrate of Example 4. FIG. 10 is a side cross-sectional view showing a process of a method for manufacturing a light source side substrate of Example 4. FIG. 10 is a side cross-sectional view showing a process of a method for manufacturing a light source side substrate of Example 4. 10 is a plan view showing a process of a method for manufacturing a light source side substrate of Example 4. FIG. 10 is a plan view showing a process of a method for manufacturing a light source side substrate of Example 4. FIG. 10 is a plan view showing a process of a method for manufacturing a light source side substrate of Example 4. FIG.

The embodiments and examples will be described below to describe the aspects of the present invention in more detail. However, the aspects of the present invention are not limited to these embodiments and examples.
[First Embodiment]
1A and 1B are diagrams illustrating a schematic configuration of a display device according to the first embodiment. FIG. 1A is a cross-sectional view showing the entire display device of the present embodiment. FIG. 1B is a cross-sectional view showing the main part of the light source side substrate. In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

In FIG. 1A, reference numeral 1 denotes a display device, and the display device 1 includes a phosphor substrate 2 and a light source side substrate 3 bonded onto the phosphor substrate 2. In the display device 1 of the present embodiment, one pixel, which is the minimum unit that constitutes an image, is configured by three dots that respectively display red, green, and blue. However, in the following description, a dot that performs red display is referred to as a red pixel PR, a dot that performs green display is referred to as a green pixel PG, and a dot that performs blue display is referred to as a blue pixel PB. In the display device 1 of the present embodiment, ultraviolet light is emitted from a light source side substrate (organic EL element substrate) 3 using an organic EL element as an excitation light source. The ultraviolet light is incident on the phosphor substrate 2 as excitation light, and red fluorescence is generated in the red pixel PR, green fluorescence is generated in the green pixel PG, and blue fluorescence is generated in the blue pixel PB, and full color display is performed by these color lights. .

(Phosphor substrate)
Hereinafter, the phosphor substrate of this embodiment will be described in detail.
The phosphor substrate 2 of the present embodiment includes a substrate 5, a phosphor layer 6 (6B, 6R, 6G), and a planarization layer 7 (first layer). The phosphor layer 6 (6B, 6R, 6G) is provided on the substrate 5, and is fluorescent by excitation light incident from the excitation light source 4 of the light source side substrate (organic EL element substrate) 3, that is, an organic EL element described later. To emit light. The planarization layer 7 is formed on the substrate 5 so as to cover the phosphor layer 6. The planarizing layer 7 is bonded to the light source side substrate 3 so as to cover the excitation light source 4 of the light source side substrate 3, whereby the light source side substrate 3 and the phosphor substrate 2 are bonded to each other and integrated. Thus, the display device 1 is configured.

The phosphor layers 6B, 6R and 6G are composed of a plurality of phosphor layers divided for each pixel. The plurality of

phosphor layers

6B, 6R, and 6G are formed of different phosphor materials as will be described later in order to emit color light of different colors depending on the pixels. Further, since the phosphor layers 6B, 6R, and 6G are planarized by the planarization layer 7, depletion between the excitation light source 4 and the phosphor layers 6B, 6R, and 6G is prevented. And the adhesiveness between the light source side board | substrate 3 and the fluorescent substance board | substrate 2 is improved.

In the phosphor substrate 2 (display device 1) having such a configuration, the refractive index of the phosphor layer 6 at the excitation light incident side interface 6a of the phosphor layer 6 is denoted by na. The refractive index of the phosphor layer 6 at the fluorescence extraction side interface 6b of the phosphor layer 6 is nb. The refractive index of the flattening layer (first layer) 7 at the portion in contact with the excitation light incident side interface 6a of the phosphor layer 6 is n1. Hereinafter, the refractive index n1 of the flattening layer (first layer) 7 in the portion in contact with the excitation light incident side interface 6a of the phosphor layer 6 is simply referred to as the refractive index n1 of the flattening layer (first layer) 7. Sometimes. The refractive index of the substrate 5 (second layer) at the portion in contact with the fluorescence extraction side interface 6b of the phosphor layer 6 is n2. Hereinafter, the refractive index n2 of the substrate 5 (second layer) in the portion of the phosphor layer 6 in contact with the fluorescence extraction side interface 6b may be simply referred to as the refractive index n2 of the substrate 5 (second layer). The refractive index na of the phosphor layer 6 at the excitation light incident side interface 6a is designed so that the refractive index of the planarizing layer (first layer) 7 is smaller than n1 (na <n1). Further, the refractive index nb of the phosphor layer 6 at the fluorescence extraction side interface 6b is designed to be larger than the refractive index of the substrate 5 (second layer) (nb> n2). However, such conditions [na <n1] and [nb> n2] may satisfy only one or both of them in the present embodiment. Further, in this embodiment, the expression “and / or” is used to mean “one or both”.

The phosphor layer 6 is configured to have a refractive index distribution between the excitation light incident side interface 6a and the fluorescence extraction side interface 6b.
When the refractive index na of the phosphor layer 6 at the excitation light incident side interface 6a is designed so that the refractive index of the planarization layer (first layer) 7 is smaller than n1 (na <n1), The difference (absolute value of refractive index difference, | n1-na |) between the refractive index na of the phosphor layer 6 and the refractive index n1 of the planarizing layer 7 (first layer) at the excitation light incident side interface 6a is The phosphor layer 6 is excited so as to be smaller than the difference (refractive index difference | n1-nb |) between the refractive index nb of the phosphor layer and the refractive index n1 of the planarizing layer 7 at the fluorescence extraction side interface 6b. There is a refractive index distribution between the light incident side interface 6a and the fluorescence extraction side interface 6b (| n1-na | <| n1-nb |).

Further, when the refractive index nb of the phosphor layer 6 at the fluorescence extraction side interface 6b is designed to be larger than the refractive index of the substrate 5 (second layer) (nb> n2), the fluorescence extraction side interface 6b. The difference between the refractive index nb of the phosphor layer 6 and the refractive index n2 of the substrate 5 (second layer) (absolute value of refractive index difference, | n2-nb |) is the excitation light incident side interface 6a. The phosphor layer 6 is separated from the excitation light incident side interface 6a and the fluorescence extraction so that the difference between the refractive index na of the phosphor layer 6 and the refractive index n2 of the substrate 5 becomes smaller (refractive index difference | n2-na |). It has a refractive index distribution with the side interface 6b. (| N2-nb | <| n2-na |)

Further, the refractive index na of the phosphor layer 6 at the excitation light incident side interface 6a is designed so that the refractive index of the flattening layer (first layer) 7 is smaller than n1, and the fluorescence at the fluorescence extraction side interface 6b. When the refractive index nb of the body layer 6 is designed to be larger than the refractive index of the substrate 5 (second layer) (na <n1 and nb> n2), the phosphor layer at the excitation light incident side interface 6a The difference between the refractive index na of 6 and the refractive index n1 of the planarizing layer 7 (first layer) (absolute value of refractive index difference, | n1-na |) is the phosphor layer at the fluorescence extraction side interface 6b. The refractive index nb of the phosphor layer 6 at the fluorescence extraction side interface 6b and the substrate 5 are smaller than the difference (refractive index difference | n1-nb |) between the refractive index nb of the phosphor layer and the refractive index n1 of the planarizing layer 7. The difference from the refractive index n2 of the (second layer) (absolute value of the refractive index difference, | n2− b |) is smaller than the difference (refractive index difference | n2-na |) between the refractive index na of the phosphor layer 6 and the refractive index n2 of the substrate 5 at the excitation light incident side interface 6a. The layer 6 has a refractive index distribution between the excitation light incident side interface 6a and the fluorescence extraction side interface 6b. (| N1-na | <| n1-nb | and | n2-nb | <| n2-na |).

That is, the difference (| n1-na |) between the refractive index na of the phosphor layer 6 and the refractive index n1 of the planarizing layer 7 (first layer) at the excitation light incident side interface 6a, and / or The difference between the refractive index nb of the phosphor layer 6 and the refractive index n2 of the substrate 5 (second layer) (| n2-nb |) at the fluorescence extraction side interface 6b is reduced so that the phosphor layer 6 Is formed. Compared to the difference in refractive index at each interface between the phosphor layer and the adjacent layer in the case of a conventional phosphor layer formed of a uniform single layer having no refractive index distribution, the phosphor layer 6 is a phosphor layer. 6 and the adjacent layers (the first layer and the second layer) are formed so that the difference in refractive index is small. That is, the phosphor layer 6 of the present embodiment is formed so that the phosphor layer 6 has a refractive index distribution in the thickness direction.

Here, FIG. 2 shows a first model of a conventional phosphor substrate (display device) in which the phosphor layer 6 does not have a refractive index distribution. The first model shown in FIG. 2 is different from the phosphor substrate (display device) shown in FIG. 1A in that the phosphor layer 6 does not have a refractive index distribution. Therefore, the refractive index is uniformly formed from the excitation light incident side interface 6a to the fluorescence extraction side interface 6b.
In this model, the refractive index n1 of the flattening layer 7 in contact with the phosphor layer 6 at the excitation light incident side interface 6a is higher than the refractive index n of the phosphor layer 6 at the excitation light incident side interface 6a of the phosphor layer 6. Further, the refractive index n2 of the substrate 5 in contact with the phosphor layer 6 at the fluorescence extraction side interface 6b is lower than the refractive index n of the phosphor layer 6 at the fluorescence extraction side interface 6b of the phosphor layer 6. . (N1>n> n2)

In such a first model, when excitation light is incident on the phosphor layer 6 from the outside (excitation light source 4) as shown by a solid line in FIG. 2, the excitation light is incident on the phosphor layer 6 at an angle exceeding the critical angle. Is totally reflected at the excitation light incident side interface 6a of the phosphor layer 6 as indicated by a broken line in FIG. Therefore, the phosphor layer 6 cannot be excited efficiently, and the light emission efficiency obtained is lowered.
Further, as shown by the solid line in FIG. 2, when the fluorescent light is transmitted from the fluorescent material layer 6 through the substrate 5 and emitted to the outside, the fluorescent light emitted from the fluorescent material layer 6 to the substrate 5 side at an angle exceeding the critical angle is shown in FIG. 2 is totally reflected at the fluorescence extraction side interface 6b of the phosphor layer 6 as indicated by a broken line. Therefore, the light extraction efficiency is lowered, and the obtained light emission efficiency is lowered.

FIG. 3A shows a second model in which the phosphor layer 6 does not have a refractive index distribution, and a protective layer 8 is interposed between the phosphor layer 6 and the planarization layer 7. In this second model, the protective layer 8 reduces the difference between the refractive index n of the phosphor layer 6 and the refractive index n1 of the flattening layer 7 in contact with the excitation light incident side interface 6a of the phosphor layer 6. . That is, the refractive index of the protective layer 8 decreases from the refractive index n1 of the planarizing layer 7 toward the refractive index n of the phosphor layer 6.
When such a protective layer 8 is provided, the refractive index n of the phosphor layer 6 at the excitation light incident side interface 6a of the phosphor layer 6 and the protective layer 8 in contact with the phosphor layer 6 at the excitation light incident side interface 6a. The refractive index difference between them becomes small. Therefore, since total reflection hardly occurs, the excitation light component incident on the phosphor layer 6 increases as shown by the solid line in FIG. 3A, and the phosphor layer 6 is excited efficiently.

However, no protective layer is provided between the phosphor layer 6 and the substrate 5. As shown by the solid line in FIG. 3A, when the fluorescence is transmitted from the phosphor layer 6 through the substrate 5 and emitted to the outside, the fluorescence emitted from the phosphor layer 6 to the substrate 5 side at an angle exceeding the critical angle is shown in FIG. 3A. As indicated by the broken line, the light is totally reflected at the fluorescence extraction side interface 6b of the phosphor layer 6. Therefore, the light extraction efficiency is lowered, and the obtained light emission efficiency is lowered.

FIG. 3B shows a third model in which the phosphor layer 6 does not have a refractive index distribution, and a protective layer 9 is interposed between the phosphor layer 6 and the substrate 5. In this third model, the protective layer 9 reduces the difference between the refractive index n of the phosphor layer 6 and the refractive index n2 of the substrate 5 on the fluorescence extraction side interface 6b side of the phosphor layer 6. That is, the refractive index of the protective layer 9 decreases from the refractive index n of the phosphor layer 7 toward the refractive index n2 of the substrate 5.
When such a protective layer 9 is provided, between the refractive index n of the phosphor layer 6 at the fluorescence extraction side interface 6b of the phosphor layer 6 and the protection layer 9 in contact with the phosphor layer at the fluorescence extraction side interface 6b. The refractive index difference is reduced. Accordingly, since total reflection hardly occurs, it is possible to efficiently extract light from the phosphor layer 6 to the outside as shown by a solid line in FIG. 3B.

However, no protective layer is provided between the phosphor layer 6 and the flattening layer 7. As shown by the solid line in FIG. 3B, when excitation light is incident on the phosphor layer 6 from the outside (excitation light source 4), the fluorescence emitted from the phosphor layer 6 toward the substrate 5 at an angle exceeding the critical angle is indicated by the broken line in FIG. 3B. As shown in FIG. 2, the phosphor layer 6 is totally reflected at the excitation light incident side interface 6a. Therefore, the phosphor layer 6 cannot be excited efficiently, and the light emission efficiency obtained is lowered.

That is, in the second and third models using the protective layer 8 (9), only one of the excitation light incident side interface 6a and the fluorescence extraction side interface 6b of the phosphor layer 6 is effective. Therefore, the effect of reducing power consumption becomes insufficient. Moreover, if the protective layer is applied to both the excitation light incident side interface 6a and the fluorescence extraction side interface 6b, the effect of reducing power consumption is enhanced, but the yield is reduced by adding a protective layer forming process in manufacturing. Furthermore, material costs and process costs also increase.

In the present embodiment, by paying attention to the refractive index of the phosphor layer 6 at the excitation light incident side interface 6a and the fluorescence extraction side interface 6b of the phosphor layer 6, as shown in FIG. The light is incident on the layer 6 and the fluorescence from the phosphor layer 6 is efficiently extracted to the outside.
That is, by providing the phosphor layer 6 with a refractive index distribution, excitation light is absorbed by the phosphor layer 6 due to a difference in refractive index at the excitation light incident side interface 6a of the phosphor layer 6 without adding a new layer. The component (total reflection component) that is reflected and lost without being reduced can be reduced, and the amount of fluorescence generated in the phosphor layer 6 can be increased. And / or a component (total reflection component) that is reflected and lost without being extracted to the outside due to a difference in refractive index at the fluorescence extraction-side interface 6b of the phosphor layer 6 to reduce light emission from the phosphor layer 6 efficiently. It can be taken out of the substrate well.
Moreover, since the phosphor layer 6 which is a light emitting part of the display and the display device has a refractive index distribution, low power consumption can be achieved, so that yield reduction and cost increase due to the addition of the protective layer can be avoided.

Hereinafter, the constituent members of the phosphor substrate 2 according to the present embodiment will be specifically described.
"substrate"
As the substrate 5 for the phosphor substrate 2 used in the present embodiment, it is necessary to take out light from the phosphor layer 6 to the outside, and thus it is necessary to transmit light in the emission wavelength region of the phosphor. Accordingly, examples of the material of the substrate 5 include an inorganic material substrate made of glass, quartz, and the like, a plastic substrate made of polyethylene terephthalate, polycarbazole, polyimide, and the like. However, as described above, the present embodiment is not limited to these substrates. Here, it is preferable to use a plastic substrate from the viewpoint that it can be bent or bent without causing stress. Further, from the viewpoint of improving gas barrier properties, it is more preferable to use a substrate in which a plastic substrate is coated with an inorganic material. Thereby, it is possible to eliminate the deterioration of the organic EL element due to the permeation of moisture which may occur when the plastic substrate is used as the organic EL substrate.

`` Phosphor layer ''
As shown in FIG. 1A, the phosphor layer 6 absorbs excitation light (ultraviolet light) from an ultraviolet light emitting organic EL element (excitation light source 4) in the present embodiment, and light having a wavelength in the red region (red light), green It is composed of a red phosphor layer 6R, a green phosphor layer 6G, and a blue phosphor layer 6B that respectively emit light having a wavelength in the region (green light) and light having a wavelength in the blue region (blue light). Further, as described above, the refractive index na of the phosphor layer 6 at the excitation light incident side interface 6a is a planarization layer (first layer) in contact with the phosphor layer 6 at the excitation light incident side interface 6a of the phosphor layer 6. ) 7 and / or the refractive index nb of the phosphor layer 6 at the fluorescence extraction side interface 6 b is in contact with the phosphor layer 6 at the fluorescence extraction side interface 6 b of the phosphor layer 6. It has a refractive index distribution so as to be larger than the refractive index of the (second layer).

It is preferable that this refractive index distribution changes continuously, that is, stepwise from the excitation light incident side interface 6a of the phosphor layer 6 toward the fluorescence extraction side interface 6b. Such a refractive index distribution can be formed by, for example, a stacked structure in which a plurality of phosphor layers having different refractive indexes are stacked. Specifically, it can be adjusted by the dispersion concentration of the inorganic phosphor in the phosphor layer 6 as shown in the examples described later. It can also be adjusted by the particle size distribution of the inorganic phosphor in the phosphor layer 6. Furthermore, the refractive index distribution can be adjusted by changing the type of polymer material (binding resin) in which the phosphor material is dispersed.

Further, as the phosphor layer 6, a phosphor layer emitting cyan light and yellow light may be added to the pixels as necessary. In that case, the color purity of each pixel emitting cyan light and yellow light is set outside the triangle connected by the points indicating the color purity of the pixels emitting red light, green light, and blue light on the chromaticity diagram. As a result, the color reproduction range can be expanded as compared with a display device using pixels that emit light of three primary colors of red, green, and blue.

The phosphor layers 6A, 6B, and 6C may be composed of only the phosphor materials exemplified below, and may optionally contain additives and the like, and these phosphor materials are polymer materials (binding). Resin) or dispersed in an inorganic material. A known phosphor material can be used as the phosphor material of the present embodiment. This type of phosphor material is classified into an organic phosphor material and an inorganic phosphor material, and specific compounds thereof are exemplified below. However, this embodiment is not limited to these materials.

Examples of organic phosphor materials include blue fluorescent dyes (fluorescent dyes that convert ultraviolet excitation light into blue light), stilbenzene dyes: 1,4-bis (2-methylstyryl) benzene, trans-4,4 Examples include '-diphenylstilbenzene, coumarin dyes: 7-hydroxy-4-methylcoumarin. Further, as green fluorescent dyes (fluorescent dyes that convert ultraviolet and blue excitation light into green light), coumarin dyes: 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidine (9 , 9a, 1-gh) Coumarin (coumarin 153), 3- (2'-benzothiazolyl) -7-diethylaminocoumarin (coumarin 6), 3- (2'-benzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin) 7), naphthalimide dyes: basic yellow 51, solvent yellow 11, solvent yellow 116 and the like. Further, as a red fluorescent dye (fluorescent dye that converts ultraviolet and blue excitation light into red light), cyanine dye: 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H- Pyran, pyridine dye: 1-ethyl-2- [4- (p-dimethylaminophenyl) -1,3-butadienyl] -pyridinium-perchlorate, and rhodamine dye: rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, basic violet 11, sulforhodamine 101 and the like.

In addition, as an inorganic phosphor material, as a blue phosphor (fluorescent dye that converts ultraviolet excitation light into blue light), Sr ₂ P ₂ O ₇ : Sn ⁴⁺ , Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , SrGa ₂ S ₄ : Ce ³⁺ , CaGa ₂ S ₄ : Ce ³⁺ , (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ : Eu ²⁺ , (Sr, Ca, Ba ₂ , 0Mg ) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , BaAl ₂ SiO ₈ : Eu ²⁺ , Sr ₂ P ₂ O ₇ : Eu ²⁺ , Sr ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ , (Sr, Ca, Ba) _{_{_{^{5 (PO 4) 3 Cl:}}}} Eu 2+, BaMg 2 Al 16 O 27: Eu 2+, (Ba, Ca) 5 (PO 4) 3 Cl: Eu 2+, Ba 3 MgSi 2 O 8: ^{_{_{u 2+, Sr 3 MgSi 2 O}}} 8: Eu 2+ and the like. Further, as a green phosphor (fluorescent dye that converts ultraviolet and blue excitation light into green light), (BaMg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ , Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , (SrBa) Al ₁₂ Si ₂ O ₈ : Eu ²⁺ , (BaMg) ₂ SiO ₄ : Eu ²⁺ , Y ₂ SiO ₅ : Ce ³⁺ , Tb ³⁺ , Sr ₂ P ₂ O ₇ -Sr ₂ B ₂ O ₅ : Eu ²⁺ , (BaCaMg) ) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ , Sr ₂ Si ₃ O ₈ -2SrCl ₂ : Eu ²⁺ , Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : Ce ³⁺ , Tb ³⁺ , Ba ₂ SiO ₄ : Eu ²⁺ , Sr ₂ SiO ₄ : Eu ²⁺ , (BaSr) SiO ₄ : Eu ^{2+ and the} like.
As red phosphors (fluorescent dyes that convert ultraviolet and blue excitation light into red light), Y ₂ O ₂ S: Eu ³⁺ , YAlO ₃ : Eu ³⁺ , Ca ₂ Y ₂ (SiO ₄ ) ₆ : Eu ³⁺ , LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺ , YVO ₄ : Eu ³⁺ , CaS: Eu ³⁺ , Gd ₂ O ₃ : Eu ³⁺ , Gd ₂ O ₂ S: Eu ³⁺ , Y (P, V) O _{^{_{_{4: Eu 3+, Mg 4 GeO}}}} 5.5 F: Mn 4+, Mg 4 GeO 6: Mn 4+, K 5 Eu 2.5 (WO 4) 6.25, Na 5 Eu 2.5 (WO 4) 6. ₂₅ , K ₅ Eu _2.5 (MoO ₄ ) _6.25 , Na ₅ Eu _2.5 (MoO ₄ ) _{6.25, and the} like.

The inorganic phosphor may be subjected to surface modification treatment as necessary. Examples of the surface modification method include a chemical treatment such as a silane coupling agent, a physical treatment by adding submicron order fine particles, and a combination of these. In consideration of stability such as deterioration due to excitation light and deterioration due to light emission, it is preferable to use an inorganic material. Further, when an inorganic material is used, the average particle diameter (d ₅₀ ) is preferably 0.5 μm to 50 μm. When the average particle size is 1 μm or less, the luminous efficiency of the phosphor is rapidly reduced. If it is 50 μm or more, it becomes very difficult to form a flat film, and depletion occurs between the phosphor layer and the organic EL element. For example, a depletion (air layer) with a refractive index of 1.0 is formed between an inorganic phosphor layer with a refractive index of about 2.0 and an organic EL element (excitation light source 4) with a refractive index of about 1.7. . Then, the light from the organic EL element (excitation light source 4) does not efficiently reach the phosphor layers 6R, 6G, 6B, and the luminous efficiency of the phosphor layers 6R, 6G, 6B decreases.

The phosphor layers 6R, 6G, and 6B are formed by using a phosphor layer forming coating solution obtained by dissolving and dispersing the phosphor material and the resin material in a solvent, using a spin coating method, a dipping method, or a doctor blade method. A known wet process such as a coating method such as a discharge coating method, a spray coating method, an ink jet method, a relief printing method, an intaglio printing method, a screen printing method, a micro gravure coating method, or the like. It can be formed by a known dry process such as a method, an electron beam (EB) vapor deposition method, a molecular beam epitaxy (MBE) method, a sputtering method, an organic vapor phase vapor deposition (OVPD) method, or a laser transfer method.

By using a photosensitive resin as the resin material, the phosphor layers 6R, 6G, and 6B can be patterned by a photolithography method. As the photosensitive resin, one or more types of photosensitive resin (photo-curable resist material) having a reactive vinyl group such as acrylic resin, methacrylic resin, polyvinyl cinnamate resin, and hard rubber resin. Various types of mixtures can be used. Also, wet processes such as the ink jet method, relief printing method, intaglio printing method, screen printing method, resistance heating vapor deposition method using shadow mask, electron beam (EB) vapor deposition method, molecular beam epitaxy (MBE) method, sputtering It is also possible to directly pattern the phosphor material by a known dry process such as an organic vapor deposition (OVPD) method or a laser transfer method.

The film thickness of the phosphor layers 6R, 6G, and 6B is preferably about 100 nm to 100 μm, and more preferably about 1 μm to 100 μm. When the film thickness is less than 100 nm, particularly when the organic EL emits blue light as in the first modification described later, the light emission from the organic EL cannot be sufficiently absorbed. Color purity is lowered by mixing blue transmitted light with color light.
Therefore, in order to increase absorption of light emitted from the organic EL element (excitation light source 4) and reduce blue transmitted light to such an extent that the color purity is not adversely affected, the film thickness is preferably set to 1 μm or more. Further, if the film thickness exceeds 100 μm, the blue light emission from the organic EL element (excitation light source 4) is already sufficiently absorbed, so that the efficiency is not increased, and only the material is consumed, and the material cost is increased. Connected.

"Planarization layer"
As shown in FIG. 1A, the flattening layer 7 is bonded to the light source side substrate 3 so as to cover the excitation light source 4 of the light source side substrate 3, so that the light source side substrate 3 and the phosphor substrate 2 are bonded to each other. Combined and integrated. Such a planarizing layer 7 functions as the first layer in the present embodiment as described above. The planarizing layer 7 has a refractive index n1 at the interface contacting the excitation light incident side interface 6a of the phosphor layer 6 larger than the refractive index nb of the phosphor layer 6 at the fluorescence extraction side interface 6b of the phosphor layer 6. It is comprised so that it may become.
Specifically, an acrylic resin having a refractive index (n1) of 1.7 or the like is used as the planarizing layer 7, but other transparent resins can be used as long as the refractive index nb of the phosphor layer 6 is larger. It can be used. In addition, as a method for forming such a flattening layer 7, a spin coat method is preferably employed in order to function as a flattening layer.

(Organic EL device substrate)
Next, the light source side substrate 3 that functions as a light source in the display device 1 of the present embodiment will be described.
As shown in FIG. 1B, the light source side substrate 3 of the present embodiment has an anode (first electrode) 13, a hole injection layer 14, a hole transport layer 15, a light emitting layer 16, and hole blocking on one surface of the substrate body 22. A plurality of organic EL elements 10 having a configuration in which a layer 17, an electron transport layer 18, an electron injection layer 19, and a cathode (second electrode) 20 are sequentially stacked are provided. And the organic EL element 10 comprises the excitation light source 4 shown to FIG. 1A. An edge cover 21 is formed so as to cover the end face of the anode 13.

The organic EL element 10 (excitation light source 4) in the light source side substrate 3 of the present embodiment emits ultraviolet light, and the emission peak of ultraviolet light is preferably 360 nm to 410 nm. However, a known element can be used as the organic EL element 10, and it is sufficient that at least an organic EL layer made of an organic light emitting material is included between the anode 13 and the cathode 20, and the specific configuration is as described above. It is not limited to. In the following description, layers from the hole injection layer 14 to the electron injection layer 19 may be referred to as an organic EL layer.

The plurality of organic EL elements 10 are provided in a matrix corresponding to each of the red pixel PR, the green pixel PG, and the blue pixel PB, and are individually controlled to be turned on / off.
The driving method of the plurality of organic EL elements 10 may be active matrix driving or passive matrix driving. A configuration example using an active matrix driving organic EL element substrate will be described in detail in a second embodiment later.

Hereinafter, each component of the organic EL element substrate will be described in detail.
As the substrate body 22, substantially the same material as the substrate 5 of the phosphor substrate 2 can be used. That is, as a material of the substrate body 22, for example, an inorganic material substrate made of glass, quartz or the like, a plastic substrate made of polyethylene terephthalate, polycarbazole, polyimide, or the like, an insulating substrate such as a ceramic substrate made of alumina, or the like, or aluminum (Al ), A metal substrate made of iron (Fe) or the like, or a substrate coated with an insulator made of silicon oxide (SiO ₂ ) or an organic insulating material on another substrate, or a metal substrate made of Al or the like. Although the board | substrate etc. which performed the insulation process by methods, such as an anodic oxidation, are mentioned, This embodiment is not limited to these board | substrates.

However, it is preferable to use a plastic substrate or a metal substrate from the viewpoint that it can be bent or bent without causing stress. Furthermore, a substrate in which a plastic substrate is coated with an inorganic material and a substrate in which a metal substrate is coated with an inorganic insulating material are more preferable. Accordingly, it is possible to eliminate the deterioration of the organic EL due to the permeation of moisture that may occur when a plastic substrate is used as the organic EL substrate. Further, it is possible to eliminate leakage (short circuit) due to protrusions of the metal substrate that may occur when a metal substrate is used as the organic EL substrate. In general, since the thickness of the organic EL layer is very thin, about 100 nm to 200 nm, it is known that when the metal substrate has a protrusion, a leak current or a short circuit occurs in the pixel portion.
Further, when the light from the organic EL layer is extracted from the side opposite to the substrate, there is no restriction as the substrate body 22, but when the light from the organic EL layer is extracted from the substrate side, a transparent or translucent substrate is used. It is necessary to use the main body 22.

Next, as an electrode material for forming the anode 13 and the cathode 20, a known electrode material can be used. In the case of the anode 13, from the viewpoint of efficiently injecting holes into the light emitting layer 16, a metal such as gold (Au), platinum (Pt), nickel (Ni) having a work function of 4.5 eV or more, In addition, an oxide (ITO) composed of indium (In) and tin (Sn), an oxide (SnO ₂ ) of tin (Sn), an oxide (IZO) composed of indium (In) and zinc (Zn), and the like are transparent electrodes. As a material. Further, in the case of the cathode 20, from the viewpoint of more efficiently injecting electrons into the light emitting layer 16, lithium (Li), calcium (Ca), cerium (Ce), barium (with a work function of 4.5 eV or less) Examples thereof include metals such as Ba) and aluminum (Al), and alloys such as Mg: Ag alloy and Li: Al alloy containing these metals.

The anode 13 and the cathode 20 can be formed by a known method such as an EB vapor deposition method, a sputtering method, an ion plating method, or a resistance heating vapor deposition method using the above-described materials. It is not limited to. Further, if necessary, the formed electrode can be patterned by a photolithography method or a laser peeling method, and a directly patterned electrode can also be formed by combining with a shadow mask. The film thickness of the anode 13 and the cathode 20 is preferably 50 nm or more. When the film thickness is less than 50 nm, the wiring resistance is increased, which may increase the drive voltage.

When the microcavity effect is used for the purpose of improving color purity, light emission efficiency, front luminance, etc., when light from the light emitting layer 16 is extracted from the anode 13 side (cathode 20 side), the anode 13 (cathode) It is preferable to use a semitransparent electrode as 20). As a material used here, a metal translucent electrode alone or a combination of a metal translucent electrode and a transparent electrode material can be used. As the translucent electrode material, silver is preferable from the viewpoints of reflectance and transmittance. The film thickness of the translucent electrode is preferably 5 nm to 30 nm. When the film thickness is less than 5 nm, the light is not sufficiently reflected, and a sufficient interference effect cannot be obtained. On the other hand, when the film thickness exceeds 30 nm, the light transmittance is drastically reduced, so that the luminance and efficiency may be lowered. Moreover, it is preferable to use an electrode with a high light reflectivity for the electrode opposite to the light extraction side.
Examples of electrode materials used in this case include reflective metal electrodes such as aluminum, silver, gold, aluminum-lithium alloys, aluminum-neodymium alloys, and aluminum-silicon alloys, and transparent and reflective metal electrodes (reflective electrodes). A combined electrode or the like can be given.

The organic EL layer used in the present embodiment may have a single layer structure of an organic light emitting layer, or a multilayer structure of an organic light emitting layer, a charge transport layer, and a charge injection layer. The present embodiment is not limited to these.
(1) Organic light emitting layer (2) Hole transport layer / organic light emitting layer (3) Organic light emitting layer / electron transport layer (4) Hole transport layer / organic light emitting layer / electron transport layer (5) Hole injection layer / Hole transport layer / organic light emitting layer / electron transport layer (6) hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer (7) hole injection layer / hole transport layer / organic Light emitting layer / hole blocking layer / electron transport layer (8) hole injection layer / hole transport layer / organic light emitting layer / hole blocking layer / electron transport layer / electron injection layer (9) hole injection layer / hole Transport Layer / Electron Blocking Layer / Organic Light-Emitting Layer / Hole Blocking Layer / Electron Transport Layer / Electron Injection Layer In this embodiment, as shown in FIG. 1B, (8) above is adopted.

In the above configuration example, each of the light emitting layer, the hole injection layer, the hole transport layer, the hole blocking layer, the electron blocking layer, the electron transport layer, and the electron injection layer may have a single layer structure or a multilayer structure. . The organic light emitting layer may be comprised only from the organic light emitting material illustrated below, and may be comprised from the combination of a luminescent dopant and host material. Further, it may optionally contain a hole transport material, an electron transport material, an additive (donor, acceptor, etc.), etc., and these materials are dispersed in a polymer material (binding resin) or an inorganic material. It may be. From the viewpoint of luminous efficiency and lifetime, those in which a luminescent dopant is dispersed in a host material are preferable.

As the organic light emitting material, a known light emitting material for organic EL can be used. Such light-emitting materials are classified into low-molecular light-emitting materials, polymer light-emitting materials, and the like. Specific examples of these compounds are given below, but the present embodiment is not limited to these materials. The light-emitting material may be classified into a fluorescent material, a phosphorescent material, and the like. In that case, it is preferable to use a phosphorescent material with high light emission efficiency from the viewpoint of reducing power consumption.

As the light-emitting dopant optionally contained in the light-emitting layer, a known dopant material for organic EL can be used. Examples of such dopant materials include, for example, p-quaterphenyl, 3,5,3,5 tetra-t-butylsecphenyl, 3,5,3,5 tetra-t-butyl-p. -Fluorescent materials such as quinckphenyl. Fluorescent light-emitting materials such as styryl derivatives, bis [(4,6-difluorophenyl) -pyridinato-N, C2 ′] picolinate iridium (III) (FIrpic), bis (4 ′, 6′-difluorophenyl) And phosphorescent organometallic complexes such as polydinato) tetrakis (1-pyrazolyl) borate iridium (III) (FIr ₆ ).

Further, as a host material when using a dopant, a known host material for organic EL can be used. Examples of such host materials include the low-molecular light-emitting materials, polymer light-emitting materials, 4,4′-bis (carbazole) biphenyl, 9,9-di (4-dicarbazole-benzyl) fluorene (CPF), 3 , 6-bis (triphenylsilyl) carbazole (mCP), carbazole derivatives such as (PCF), aniline derivatives such as 4- (diphenylphosphoyl) -N, N-diphenylaniline (HM-A1), 1,3- And fluorene derivatives such as bis (9-phenyl-9H-fluoren-9-yl) benzene (mDPFB) and 1,4-bis (9-phenyl-9H-fluoren-9-yl) benzene (pDPFB).

The charge injection and transport layer is used to efficiently inject charges (holes and electrons) from the electrode and transport (injection) to the light-emitting layer with the charge injection layer (hole injection layer and electron injection layer) and the charge. It is classified as a transport layer (hole transport layer, electron transport layer). The charge injecting and transporting layer may be composed of only the charge injecting and transporting material exemplified below, and may optionally contain additives (donor, acceptor, etc.), and these materials are polymer materials (conjugation). Wear resin) or a structure dispersed in an inorganic material.

As the charge injecting and transporting material, known charge transporting materials for organic EL and organic photoconductors can be used. Such charge injecting and transporting materials are classified into hole injecting and transporting materials and electron injecting and transporting materials. Specific examples of these compounds are given below, but this embodiment is not limited to these materials. .
Examples of hole injection and hole transport materials include oxides such as vanadium oxide (V ₂ O ₅ ) and molybdenum oxide (MoO ₂ ), inorganic p-type semiconductor materials, porphyrin compounds, N, N′-bis (3 -Methylphenyl) -N, N′-bis (phenyl) -benzidine (TPD), N, N′-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine (NPD), etc. Low molecular weight materials such as tertiary amine compounds, hydrazone compounds, quinacridone compounds, styrylamine compounds, polyaniline (PANI), polyaniline-camphor sulfonic acid (PANI-CSA), 3,4-polyethylenedioxythiophene / polystyrene sulfonate ( PEDOT / PSS), poly (triphenylamine) derivative (Poly-TPD), polyvinylcarbazole (P VCz), poly (p-phenylene vinylene) (PPV), poly (p-naphthalene vinylene) (PNV), and the like.

In addition, for the purpose of more efficiently injecting and transporting holes from the anode, the material used as the hole injection layer is the highest occupied molecular orbit (HOMO) than the hole injection transport material used for the hole transport layer. It is preferable to use a material having a low energy level. Further, as the hole transport layer, it is preferable to use a material having a higher hole mobility than the hole injection transport material used for the hole injection layer.

In order to further improve the hole injection and transport properties, the hole injection and transport material is preferably doped with an acceptor. As the acceptor, a known acceptor material for organic EL can be used. Although these specific compounds are illustrated below, this embodiment is not limited to these materials.
Acceptor materials include Au, Pt, W, Ir, POCl ₃ , AsF ₆ , Cl, Br, I, vanadium oxide (V ₂ O ₅ ), molybdenum oxide (MoO ₂ ), and other inorganic materials, TCNQ (7, 7 , 8,8, -tetracyanoquinodimethane), TCNQF ₄ (tetrafluorotetracyanoquinodimethane), TCNE (tetracyanoethylene), HCNB (hexacyanobutadiene), DDQ (dicyclodicyanobenzoquinone), etc. And compounds having a nitro group such as TNF (trinitrofluorenone) and DNF (dinitrofluorenone), and organic materials such as fluoranyl, chloranil and bromanyl. Among these, compounds having a cyano group such as TCNQ, TCNQF ₄ , TCNE, HCNB, DDQ and the like are more preferable because the carrier concentration can be increased more effectively.

Examples of electron injection and electron transport materials include inorganic materials that are n-type semiconductors, oxadiazole derivatives, triazole derivatives, thiopyrazine dioxide derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, diphenoquinone derivatives, fluorenone derivatives, benzodifuran derivatives. And low molecular weight materials such as poly (oxadiazole) (Poly-OXZ) and polystyrene derivatives (PSS). In particular, examples of the electron injection material include fluorides such as lithium fluoride (LiF) and barium fluoride (BaF ₂ ), and oxides such as lithium oxide (Li ₂ O).

For the purpose of more efficiently injecting and transporting electrons from the cathode, the material used for the electron injection layer has a higher energy level of the lowest unoccupied molecular orbital (LUMO) than the electron injection transport material used for the electron transport layer. It is preferable to use a material. In addition, as a material used for the electron transport layer, it is preferable to use a material having higher electron mobility than the electron injection transport material used for the electron injection layer.
In order to further improve the electron injection and transport properties, the electron injection and transport material is preferably doped with a donor. As the donor, a known donor material for organic EL can be used. Although these specific compounds are illustrated below, this embodiment is not limited to these materials.

Donor materials include inorganic materials such as alkali metals, alkaline earth metals, rare earth elements, Al, Ag, Cu, In, anilines, phenylenediamines, benzidines (N, N, N ′, N′-tetraphenyl) Benzidine, N, N'-bis- (3-methylphenyl) -N, N'-bis- (phenyl) -benzidine, N, N'-di (naphthalen-1-yl) -N, N'-diphenyl- Benzidine, etc.), triphenylamines (triphenylamine, 4,4′4 ″ -tris (N, N-diphenyl-amino) -triphenylamine, 4,4′4 ″ -tris (N-3- Methylphenyl-N-phenyl-amino) -triphenylamine, 4,4′4 ″ -tris (N- (1-naphthyl) -N-phenyl-amino) -triphenylamine, etc.), triphenyldiamines ( N, N'- Compounds having an aromatic tertiary amine skeleton such as di- (4-methyl-phenyl) -N, N′-diphenyl-1,4-phenylenediamine), phenanthrene, pyrene, perylene, anthracene, tetracene, pentacene, etc. There are organic materials such as condensed polycyclic compounds (wherein the condensed polycyclic compounds may have a substituent), TTF (tetrathiafulvalene) s, dibenzofuran, phenothiazine, and carbazole.
Among these, a compound having an aromatic tertiary amine as a skeleton, a condensed polycyclic compound, and an alkali metal are particularly preferable because the carrier concentration can be increased more effectively.

An organic EL layer including a light emitting layer, a hole transport layer, an electron transport layer, a hole injection layer, an electron injection layer, and the like is prepared using a coating liquid for forming an organic EL layer in which the above materials are dissolved and dispersed in a solvent. , Known by coating methods such as spin coating method, dipping method, doctor blade method, discharge coating method, spray coating method, ink jet method, letterpress printing method, intaglio printing method, screen printing method, microgravure coating method, etc. A known dry process such as a wet process, a resistance heating vapor deposition method using the above materials, an electron beam (EB) vapor deposition method, a molecular beam epitaxy (MBE) method, a sputtering method, an organic vapor deposition (OVPD) method, or the like It can be formed by a laser transfer method or the like. In addition, when forming an organic EL layer by a wet process, the coating liquid for organic EL layer formation may contain the additive for adjusting the physical properties of coating liquid, such as a leveling agent and a viscosity modifier.

The film thickness of each layer of the organic EL layer is preferably about 1 nm to 1000 nm, more preferably 10 nm to 200 nm. If the film thickness is less than 10 nm, the physical properties (charge injection characteristics, transport characteristics, confinement characteristics, etc.) that are originally required cannot be obtained. In addition, pixel defects due to foreign matters such as dust may occur. On the other hand, if the film thickness exceeds 200 nm, the drive voltage increases due to the resistance component of the organic EL layer, leading to an increase in power consumption.

In the case of this embodiment, an edge cover 21 is formed for the purpose of preventing leakage current between the anode 13 and the cathode 20 at the end of the anode 13. The edge cover 21 can be formed by a known method such as an EB vapor deposition method using an insulating material, a sputtering method, an ion plating method, a resistance heating vapor deposition method, or the like, by a known dry method or a wet photolithography method. Patterning can be performed, but the present embodiment is not limited to these forming methods. The material constituting the edge cover 21 can be a known insulating material, and is not particularly limited in the present embodiment, but it is necessary to transmit light. For example, SiO, SiON, SiN, SiOC, SiC, HfSiON , ZrO, HfO, LaO and the like. The film thickness of the edge cover 21 is preferably 100 nm to 2000 nm. When the thickness is 100 nm or less, the insulating property is not sufficient, and leakage occurs between the anode 13 and the cathode 20, causing an increase in power consumption and non-light emission. On the other hand, when the thickness is 2000 nm or more, the film forming process takes time, which causes a decrease in productivity and disconnection of the electrode at the edge cover 21.

The organic EL element 10 preferably has a microcavity structure (optical microresonator structure) due to an interference effect between a reflective electrode and a semitransparent electrode used as the anode 13 and the cathode 20 or a dielectric multilayer film. Thereby, it becomes possible to condense the light from the organic EL element 10 in the front direction (provide directivity). As a result, light escaping to the surroundings can be reduced, and the light emission efficiency at the front can be increased. As a result, it is possible to more efficiently propagate the light emission energy generated in the light emitting layer 16 of the organic EL element 10 to the phosphor layers 6R, 6G, 6B, and to increase the front luminance. In addition, the emission spectrum can be adjusted due to the interference effect, and the emission spectrum can be adjusted by adjusting to a desired emission peak wavelength and half width. Thereby, the spectrum which can excite the fluorescent substance which light-emits each color light more effectively can be controlled.

According to the display device 1 of the present embodiment, by paying attention to the refractive index of the phosphor layer 6 at the excitation light incident side interface 6a and the fluorescence extraction side interface 6b of the phosphor layer 6 as shown in FIG. Excitation light is efficiently incident on the phosphor layer 6 and fluorescence from the phosphor layer 6 is efficiently extracted to the outside.
That is, by providing the phosphor layer 6 with a refractive index distribution, excitation light is absorbed by the phosphor layer 6 due to a difference in refractive index at the excitation light incident side interface 6a of the phosphor layer 6 without adding a new layer. The total reflection component which is reflected and lost without being reduced can be reduced, and the amount of fluorescence generated in the phosphor layer 6 can be increased. And / or the total reflection component that is reflected and lost without being extracted to the outside due to the difference in refractive index at the fluorescence extraction side interface 6b of the phosphor layer 6 is reduced, and the light emission from the phosphor layer 6 is efficiently performed outside the substrate. Can be taken out.
In addition, low power consumption can be achieved simply by providing the phosphor layer 6 which is a light emitting part of the display and the display device with a refractive index distribution, so that yield reduction and cost increase due to the addition of the protective layer can be avoided.

Although not shown in FIG. 1A, wavelength selective transmission reflection having characteristics of transmitting the excitation light and reflecting the emission of the phosphor on the surface 6a on which the excitation light of the phosphor layers 6R, 6G, and 6B is incident. A layer may be formed as the first layer of this embodiment. This wavelength selective transmission / reflection layer needs to have a property of transmitting at least light corresponding to the peak wavelength of the excitation light and reflecting at least light corresponding to the emission peak wavelength of the phosphor layer 6. Further, the wavelength selective transmission / reflection layer has a refractive index n1 at the interface contacting the excitation light incident side interface 6a of the phosphor layer 6, and a refractive index nb of the phosphor layer 6 at the fluorescence extraction side interface 6b of the phosphor layer 6. Need to be bigger than. Examples of the material of the wavelength selective transmission / reflection layer include a dielectric multilayer film, an inorganic material film made of metal thin film glass, and the like, a resin film made of polyethylene terephthalate, polycarbazole, polyimide, and the like. Is not limited to these layers. The effect of the wavelength selective transmission / reflection layer will be described in detail in the following [Example] section.
With this wavelength selective transmission / reflection layer, excitation light from the light source side substrate 3 can be efficiently incident on the phosphor layers 6R, 6G, 6B, and isotropic in all directions from the phosphor layers 6R, 6G, 6B. It is possible to efficiently change the traveling direction of the light emitted to the front direction.

[First Modification of First Embodiment]
Hereinafter, a first modification of the embodiment will be described with reference to FIG.
The basic configuration of the display device of the present modification is the same as that of the first embodiment, and the point that the light source side substrate including the excitation light source 4 made of an organic EL element that emits blue light is used is the first embodiment. Is different.
FIG. 4 is a cross-sectional view showing a display device of this modification. In FIG. 4, the same components as those in FIG. 1A used in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 4, the display device 25 of the present modification includes a phosphor substrate 26, a light source side substrate (organic EL element substrate) 27 bonded to the phosphor substrate 26 via the planarization layer 7, It is composed of In the display device 25 of the present modification, blue light is emitted from the organic EL elements that constitute the excitation light source 4 of the light source side substrate 27. The main emission peak of blue light is preferably 410 nm to 470 nm, for example.

In the phosphor substrate 26, the red pixel PR is provided with a red phosphor layer 6R that emits red light using blue light as excitation light, and the green pixel PG emits green light using blue light as excitation light. A green phosphor layer 6G is provided. In contrast, the blue pixel PB is provided with a light scattering layer 28 for scattering incident blue light and emitting it to the outside. The light scattering layer 28 has a configuration in which, for example, particles having a refractive index different from these materials are dispersed in a light-transmitting inorganic or organic material, and the light incident on the light scattering layer 28 is a layer. It is scattered isotropically inside.

The light scattering particles used in the light scattering layer 28 may be made of an organic material or may be made of an inorganic material, but is preferably made of an inorganic material. Thereby, the light having directivity from the excitation light source 4 (organic EL element 10) can be diffused or scattered more isotropically and effectively. Further, by using an inorganic material, it is possible to provide a light scattering layer that is stable to light and heat. Moreover, it is preferable that the light scattering particles have high transparency.

When an inorganic material is used as such light scattering particles, the inorganic material may be an oxide of at least one metal selected from the group consisting of silicon, titanium, zirconium, aluminum, indium, zinc, tin, and antimony, for example. And particles (fine particles) containing as a main component.
Further, when using particles (inorganic fine particles) made of an inorganic material as light scattering particles, examples of the inorganic fine particles include silica beads (refractive index: 1.44), alumina beads (refractive index: 1.63), and titanium oxide. Examples thereof include beads (refractive index: anatase type: 2.50, rutile type: 2.70), zirconia oxide beads (refractive index: 2.05), and zinc oxide beads (refractive index: 2.00).

When particles (organic fine particles) made of an organic material are used as the light scattering particles, examples of the organic fine particles include polymethyl methacrylate beads (refractive index: 1.49), acrylic beads (refractive index: 1.50), acrylic- Styrene copolymer beads (refractive index: 1.54), melamine beads (refractive index: 1.57), high refractive index melamine beads (refractive index: 1.65), polycarbonate beads (refractive index: 1.57), Styrene beads (refractive index: 1.60), crosslinked polystyrene beads (refractive index: 1.61), polyvinyl chloride beads (refractive index: 1.60), benzoguanamine-melamine formaldehyde beads (refractive index: 1.68), Examples thereof include silicone beads (refractive index: 1.50).

The resin material used by mixing with the light scattering particles is preferably a translucent resin. Examples of the resin material include melamine resin (refractive index: 1.57), nylon (refractive index: 1.53), polystyrene (refractive index: 1.60), melamine beads (refractive index: 1.57), polycarbonate ( Refractive index: 1.57), polyvinyl chloride (refractive index: 1.60), polyvinylidene chloride (refractive index: 1.61), polyvinyl acetate (refractive index: 1.46), polyethylene (refractive index: 1 .53), polymethyl methacrylate (refractive index: 1.49), poly MBS (refractive index: 1.54), medium density polyethylene (refractive index: 1.53), high density polyethylene (refractive index: 1.54). ), Tetrafluoroethylene (refractive index: 1.35), polytrifluoroethylene chloride (refractive index: 1.42), polytetrafluoroethylene (refractive index: 1.35), and the like.

Note that the red pixel PR and the green pixel PG are formed to have a refractive index distribution as in the first embodiment. Other configurations of the display device 25 are the same as those in the first embodiment.
In the display device 25 of this modification, blue light from the light source side substrate 27 is incident on the phosphor substrate 26 as excitation light, red fluorescence is generated by the red phosphor layer 6R in the red pixel PR, and in the green pixel PG. Green fluorescence is generated by the green phosphor layer 6G. In the blue pixel PB, the incident blue light is scattered by the light scattering layer 28 and emitted as it is, and full color display is performed by these respective color lights. As described above, although the display principle of the blue pixel PB is different from that of the first embodiment, the light emission from the red phosphor layer 6 </ b> R and the green phosphor layer 6 </ b> G can be efficiently extracted to the outside of the substrate also in this modification. The same effect as the first embodiment can be obtained.

[Second Modification of First Embodiment]
Hereinafter, a second modification of the embodiment will be described with reference to FIG.
The basic configuration of the display device of this modification is the same as that of the first embodiment, and is different from the first embodiment in that each pixel includes a color filter.
FIG. 5 is a cross-sectional view showing a display device of this modification. In FIG. 5, the same components as those in FIG. 1A used in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the display device 30 of this modification, as shown in FIG. 5,

color filters

32R, 32G, and 32B are provided between the substrate 5 constituting the phosphor substrate 31 and the phosphor layers 6R, 6G, and 6B of each pixel. Is provided. The red pixel PR is provided with a red color filter 32R, the green pixel PG is provided with a green color filter 32G, and the blue pixel PB is provided with a blue color filter 32B. Conventional color filters can be used as the

color filters

32R, 32G, and 32B. However, these

color filters

32R, 32G, and 32B function as the second layer of the present embodiment in this modification. Therefore, for these

color filters

32R, 32G, and 32B, the refractive index n2 at the interface contacting the fluorescence extraction side interface 6b of the phosphor layer 6 is such that the phosphor layer 6 has the refractive index n2 at the fluorescence extraction side interface 6b. It must be smaller than the refractive index nb. Other configurations are the same as those of the first embodiment.

Also in this modification, it is possible to obtain the same effect as that of the first embodiment in which the light emitted from the phosphor layer 6 can be efficiently taken out of the substrate.
In the case of this modification, the

color filters

32R, 32G, and 32B are provided for each pixel, so that the color purity of each of the red pixel PR, the green pixel PG, and the blue pixel PB can be increased. The color reproduction range of the display device 30 can be expanded. Further, a red color filter 32R formed under the red phosphor layer 6R, a green color filter 32G formed under the green phosphor layer 6G, and a blue color filter 32B formed under the blue phosphor layer 6B. Absorbs the excitation light component contained in the external light. Therefore, it is possible to reduce or prevent light emission of the phosphor layers 6R, 6G, and 6B due to external light, and it is possible to reduce or prevent a decrease in contrast. Further, the blue color filter 32B, the green color filter 32G, and the red color filter 32R can prevent excitation light that is not absorbed by the phosphor layers 6R, 6G, and 6B from leaking outside. For this reason, it is possible to prevent the color purity of the display from being deteriorated due to a mixture of light emitted from the phosphor layers 6R, 6G and 6B and excitation light.

[Third Modification of First Embodiment]
Hereinafter, a third modification of the embodiment will be described with reference to FIGS. 6A and 6B.
The basic configuration of the display device of this modification is the same as that of the first embodiment, and is different from the first embodiment in that an LED substrate is used as the light source side substrate.
FIG. 6A is a cross-sectional view illustrating an overall configuration of a display device according to this modification. FIG. 6B is a cross-sectional view showing an LED substrate as a light source side substrate. In FIG. 6A and FIG. 6B, the same code | symbol is attached | subjected to the same component as FIG. 1A and FIG. 1B used in 1st Embodiment, and description is abbreviate | omitted.

In the display device 35 of this modification, the configuration of the phosphor substrate 2 is the same as that of the first embodiment, and the configuration of the excitation light source 4 is different. As shown in FIG. 6B, the light source side substrate (LED substrate) 36 has a first buffer layer 38, an n-type contact layer 39, a second n-type cladding layer 40, and a first n-type on one surface of the substrate body 37. A cladding layer 41, an active layer 42, a first p-type cladding layer 43, a second p-type cladding layer 44, and a second buffer layer 45 are sequentially stacked, and a cathode 46 is formed on the n-type contact layer 39. An LED (light emitting diode) 48 having a configuration in which an anode 47 is formed on the second buffer layer 45 is provided. In addition, although other well-known LED, for example, ultraviolet light emission inorganic LED, blue light emission inorganic LED, etc. can be used as LED, A specific structure is not restricted to the above-mentioned thing.

Hereinafter, each component of the light source side substrate (LED substrate) 36 will be described in detail.
The active layer 42 used in this modification is a layer that emits light by recombination of electrons and holes. As the material of the active layer 42, a known active layer material for LED can be used. Examples of the active layer material, for example, as ultraviolet active layer _{_{_{material, AlGaN, InAlN, In a Al}}} b Ga 1-a-b N (0 ≦ a, 0 ≦ b, a + b ≦ 1), as a blue active layer material Includes In _z Ga _1-z N (0 <z <1) and the like, but this embodiment is not limited thereto.
Moreover, as the active layer 42, a single quantum well structure or a multiple quantum well structure is used. The active layer of the quantum well structure may be either n-type or p-type. However, when it is a non-doped (no impurity added) active layer, the half-value width of the emission wavelength is narrowed due to interband emission, and light emission with good color purity is achieved. Since it is obtained, it is preferable.

The active layer 42 may be doped with at least one of a donor impurity and an acceptor impurity. If the crystallinity of the active layer doped with the impurity is the same as that of the non-doped layer, the emission intensity between bands can be further increased by doping the donor impurity as compared with the non-doped layer. When the acceptor impurity is doped, the peak wavelength can be shifted to the lower energy side by about 0.5 eV from the peak wavelength of interband light emission, but the full width at half maximum is widened. When both the acceptor impurity and the donor impurity are doped, the light emission intensity can be further increased as compared with the light emission intensity of the active layer doped only with the acceptor impurity. In particular, when an active layer doped with an acceptor impurity is formed, the conductivity type of the active layer is preferably doped with a donor impurity such as Si to be n-type.

As the n-type cladding layers 40 and 41 used in this modification, a known n-type cladding layer material for LED can be used, and a single layer or a multilayer structure may be used. When the n-type cladding layers 40 and 41 are formed of an n-type semiconductor having a larger band gap energy than the active layer 42, a potential barrier against holes is formed between the n-type cladding layers 40 and 41 and the active layer 42. Holes can be confined in the active layer 42. For example, the n _- type cladding layers 40 and 41 can be formed of n _- type In _x Ga _1-x N (0 ≦ x <1), but the present embodiment is not limited to these.

As the p-type cladding layers 43 and 44 used in this modification, a known p-type cladding layer material for LED can be used, and a single layer or a multilayer structure may be used. When the p-type cladding layers 43 and 44 are formed of a p-type semiconductor having a band gap energy larger than that of the active layer 42, a potential barrier against electrons is formed between the p-type cladding layers 43 and 44 and the active layer 42. Can be confined in the active layer 42. For example, the p-type cladding layers 43 and 44 can be formed of Al _y Ga _1-y N (0 ≦ y ≦ 1), but the present embodiment is not limited to these.

As the n-type contact layer 39 used in this modification, a known contact layer material for LED can be used. For example, an n-type GaN layer is used as a layer for forming an electrode in contact with the n-type cladding layers 40 and 41. An n-type contact layer 39 can be formed. It is also possible to form a p-type contact layer made of p-type GaN as a layer for forming an electrode in contact with the p-type cladding layers 43 and 44. However, this contact layer need not be formed if the second n-type cladding layer 40 and the second p-type cladding layer 44 are made of GaN, and the second cladding layer is used as the contact layer. It is also possible.

For each of the layers used in the present modification, a known film forming process for LEDs can be used, but the present embodiment is not particularly limited thereto. For example, by using a vapor phase growth method such as MOVPE (metal organic vapor phase epitaxy), MBE (molecular beam vapor phase epitaxy), HDVPE (hydride vapor phase epitaxy), for example, sapphire (C plane, A plane, R ), SiC (including 6H—SiC, 4H—SiC), spinel (MgAl ₂ O ₄ , especially its (111) plane), ZnO, Si, GaAs, or other oxide single crystal substrates (such as NGO) ) Or the like.
Also in this modification, it is possible to obtain the same effect as that of the first embodiment in which the light emitted from the phosphor layer 6 can be efficiently taken out of the substrate.

[Fourth Modification of First Embodiment]
Hereinafter, a fourth modification of the embodiment will be described with reference to FIGS. 7A and 7B.
The basic configuration of the display device of this modification is the same as that of the first embodiment, and is different from the first embodiment in that an inorganic EL substrate is used as the light source side substrate.
FIG. 7A is a cross-sectional view illustrating an overall configuration of a display device according to this modification. FIG. 7B is a cross-sectional view showing an inorganic EL substrate as a light source side substrate. In FIG. 7A and FIG. 7B, the same code | symbol is attached | subjected to the same component as FIG. 1A FIG. 1B used in 1st Embodiment, and description is abbreviate | omitted.

In the display device 50 of the present modification, the light source side substrate 51 (inorganic EL element substrate) includes a first electrode 53, a first dielectric layer 54, a light emitting layer 55, An inorganic EL element 58 having a structure in which a second dielectric layer 56 and a second electrode 57 are sequentially laminated is provided. As the inorganic EL element 58, a known inorganic EL, for example, an ultraviolet light emitting inorganic EL, a blue light emitting inorganic EL, or the like can be used, and the specific configuration is not limited to the above.

Hereinafter, each component of the light source side substrate 51 (inorganic EL element substrate) will be described in detail.
As the substrate body 52, the same light source side substrate 3 (organic EL element substrate) on which the organic EL element 10 described above is formed can be used.
As the first electrode 53 and the second electrode 57 used in this modification, metals such as aluminum (Al), gold (Au), platinum (Pt), nickel (Ni), and indium (In) and tin (Sn) Oxide (ITO) made of), tin (Sn) oxide (SnO ₂ ), indium (In) and oxide (IZO) made of zinc (Zn), etc., can be mentioned as transparent electrode materials. It is not limited to these materials. However, a transparent electrode such as ITO is preferable for the electrode on the side from which light is extracted, and a reflective film such as aluminum is preferably used for the electrode on the side opposite to the direction from which light is extracted.

The first electrode 53 and the second electrode 57 can be formed by a known method such as an EB vapor deposition method, a sputtering method, an ion plating method, or a resistance heating vapor deposition method using the above-described materials. It is not limited to these formation methods. If necessary, the formed electrode can be patterned by a photolithography method or a laser peeling method, or a patterned electrode can be directly formed by combining with a shadow mask. The film thickness of the first electrode 53 and the second electrode 57 is preferably 50 nm or more. When the film thickness is less than 50 nm, the wiring resistance increases and the drive voltage may increase.

As the first dielectric layer 54 and the second dielectric layer 56 used in this modification, a known dielectric material for inorganic EL can be used. Examples of such a dielectric material include tantalum pentoxide (Ta ₂ O ₅ ), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), aluminum titanate ( AlTiO ₃ ), barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ) and the like can be mentioned, but this modification is not limited thereto. Further, the first dielectric layer 54 and the second dielectric layer 56 of the present modification may be configured by one type selected from the above dielectric materials, or may be configured by stacking two or more types of materials. Good. The thickness of each

dielectric layer

54, 56 is preferably about 200 nm to 500 nm.

As the light emitting layer 55 used in this modification, a known light emitting material for inorganic EL can be used. As such a light emitting material, for example, as an ultraviolet light emitting material, ZnF ₂ : Gd, and as a blue light emitting material, BaAl ₂ S ₄ : Eu, CaAl ₂ S ₄ : Eu, ZnAl ₂ S ₄ : Eu, Ba ₂ SiS. ₄ : Ce, ZnS: Tm, SrS: Ce, SrS: Cu, CaS: Pb, (Ba, Mg) Al ₂ S ₄ : Eu, and the like are exemplified, but the present modification is not limited thereto. The film thickness of the light emitting layer 55 is preferably about 300 nm to 1000 nm.

Also in the present modification, it is possible to obtain the same effect as that of the first embodiment in which light emitted from the phosphor layer 6 can be efficiently taken out of the substrate.

As the configuration of the light source, the organic EL element is exemplified in the embodiment, the LED is exemplified in the third modification, and the inorganic EL element is exemplified in the fourth modification. In these structural examples, it is preferable to provide a sealing film or a sealing substrate for sealing a light emitting element such as an organic EL element, an LED, or an inorganic EL element. The sealing film and the sealing substrate can be formed by a known sealing material and sealing method. Specifically, the sealing film can be formed by applying a resin on the surface opposite to the substrate main body constituting the light source by using a spin coat method, an ODF, or a laminate method. Alternatively, after forming an inorganic film such as SiO, SiON, or SiN by plasma CVD, ion plating, ion beam, sputtering, etc., resin is further applied using spin coating, ODF, or lamination. Alternatively, the sealing film can be formed by bonding.

Such a sealing film or a sealing substrate can prevent entry of oxygen and moisture into the light emitting element from the outside, thereby improving the life of the light source. Further, when the light source and the phosphor substrate are bonded, they can be bonded with a general ultraviolet curable resin, a thermosetting resin, or the like. Further, when the light source is directly formed on the phosphor substrate, for example, a method of sealing an inert gas such as nitrogen gas or argon gas with a glass plate, a metal plate or the like can be mentioned. Furthermore, it is preferable to mix a moisture absorbent such as barium oxide in the enclosed inert gas. When an organic EL element is used as the light source, deterioration of the organic EL element due to moisture can be more effectively reduced. However, this embodiment is not limited to these members and forming methods. In the case where light is extracted from the side opposite to the substrate, it is necessary to use a light transmissive material for both the sealing film and the sealing substrate.

[Second Embodiment]
Hereinafter, a second embodiment will be described with reference to FIGS.
The display device of the present embodiment is a configuration example using an active matrix driving type organic EL element substrate as a light source.
FIG. 8 is a cross-sectional view showing the display device of this embodiment. FIG. 9 is a plan view showing the display device of this embodiment. In FIG. 8, the same components as those in FIG. 1A used in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 8, the display device 60 of the present embodiment includes a phosphor substrate 2 and a light source side substrate 61 (organic EL element substrate) bonded on the phosphor substrate 2. The light source side substrate 61 of the present embodiment uses an active matrix driving system using TFTs as means for switching whether to irradiate light to each of the red pixel PR, the green pixel PG, and the blue pixel PB. On the other hand, the configuration of the phosphor substrate 2 is the same as that of the first embodiment. When the light source side substrate 61 of the present embodiment emits ultraviolet light, the blue pixel PB has a blue phosphor layer that emits blue light using ultraviolet light as excitation light. Or when the light source side board | substrate 61 of this embodiment light-emits blue light, the blue pixel PB shall have a light-scattering layer which scatters blue light.

(Active matrix drive type organic EL element substrate)
Hereinafter, the active matrix driving type light source side substrate 61 of this embodiment will be described in detail.
As shown in FIG. 8, the light source side substrate 61 of this embodiment has a TFT 63 formed on one surface of the substrate body 62. That is, the gate electrode 64 and the gate line 65 are formed, and the gate insulating film 66 is formed on the substrate body 62 so as to cover the gate electrode 64 and the gate line 65. An active layer (not shown) is formed on the gate insulating film 66, and a source electrode 67, a drain electrode 68 and a data line 69 are formed on the active layer, and covers the source electrode 67, the drain electrode 68 and the data line 69. Thus, the planarizing film 70 is formed.

Note that the planarization film 70 does not have to have a single layer structure, and may be configured by combining another interlayer insulating film and the planarization film. Further, a contact hole 71 that reaches the drain electrode 68 through the planarizing film or the interlayer insulating film is formed, and the organic EL element that is electrically connected to the drain electrode 68 through the contact hole 71 on the planarizing film 70 Ten anodes 13 are formed. The configuration of the organic EL element 10 itself is the same as that of the first embodiment.

As the substrate main body 62 used for the active matrix driving type, it is preferable to use a substrate that does not melt at a temperature of 500 ° C. or less and does not cause distortion. In addition, since a general metal substrate has a coefficient of thermal expansion different from that of glass, it is difficult to form a TFT on the metal substrate with a conventional production apparatus, but the linear expansion coefficient is 1 × 10 ⁻⁵ / ° C. or less. By using a metal substrate that is an iron-nickel alloy of this type and adjusting the linear expansion coefficient to glass, a TFT can be formed on the metal substrate at low cost using a conventional production apparatus. In the case of a plastic substrate, since the heat resistant temperature is very low, the TFT can be transferred and formed on the plastic substrate by forming the TFT on the glass substrate and then transferring the TFT to the plastic substrate. Further, in the present embodiment, there is no restriction as a substrate when the light emission from the organic EL layer is taken out from the opposite side of the substrate, but when the light emission from the organic EL layer is taken out from the substrate side, it is transparent or translucent. It is necessary to use a substrate.

The TFT 63 is formed on the substrate body 62 before the organic EL element 10 is formed, and functions as a pixel switching element and an organic EL element driving element. Examples of the TFT 63 used in this embodiment include known TFTs, which can be formed using known materials, structures, and formation methods. In this embodiment, a metal-insulator-metal (MIM) diode can be used instead of the TFT 63.

As the material of the active layer of the TFT 63, for example, amorphous silicon (amorphous silicon), polycrystalline silicon (polysilicon), microcrystalline silicon, inorganic semiconductor materials such as cadmium selenide, zinc oxide, indium oxide-gallium oxide- Examples thereof include oxide semiconductor materials such as zinc oxide, or organic semiconductor materials such as polythiophene derivatives, thiophene oligomers, poly (p-ferylene vinylene) derivatives, naphthacene, and pentacene. Examples of the structure of the TFT 63 include a staggered type, an inverted staggered type, a top gate type, and a coplanar type.

As the method for forming the active layer constituting the TFT 63, (1) a method of ion doping impurities into amorphous silicon formed by plasma induced chemical vapor deposition (PECVD), and (2) a silane (SiH ₄ ) gas is used. Forming amorphous silicon by low pressure chemical vapor deposition (LPCVD), crystallizing amorphous silicon by solid phase growth to obtain polysilicon, and then ion doping by ion implantation, (3) Si ₂ H Amorphous silicon is formed by LPCVD using ₆ gases or PECVD using SiH ₄ gas, annealed by a laser such as an excimer laser, etc., and amorphous silicon is crystallized to obtain polysilicon, followed by ion doping (Low temperature process), (4) LPCVD How is a polysilicon layer is formed by a PECVD method, a gate insulating film formed by thermal oxidation at 1000 ° C. or higher, thereon to form a gate electrode of the n ⁺ polysilicon, then, ion doping ( High temperature process), (5) a method of forming an organic semiconductor material by an inkjet method, and (6) a method of obtaining a single crystal film of the organic semiconductor material.

The gate insulating film 66 of the TFT 63 used in this embodiment can be formed using a known material. Examples thereof include SiO ₂ formed by PECVD, LPCVD, etc., or SiO ₂ obtained by thermally oxidizing a polysilicon film. Further, the data line 69, the gate line 65, the source electrode 67, and the drain electrode 68 of the TFT 63 used in this embodiment can be formed using a known conductive material, for example, tantalum (Ta), aluminum (Al ), Copper (Cu), and the like. The TFT 63 according to this embodiment can be configured as described above, but is not limited to these materials, structures, and formation methods.

The interlayer insulating film used in the present embodiment can be formed using a known material. For example, silicon oxide (SiO ₂ ), silicon nitride (SiN or Si ₃ N ₄ ), tantalum oxide (TaO, Alternatively, an inorganic material such as Ta ₂ O ₅ ), an organic material such as an acrylic resin or a resist material, or the like can be given. Examples of the formation method include dry processes such as chemical vapor deposition (CVD) and vacuum deposition, and wet processes such as spin coating. Moreover, it can also pattern by the photolithographic method etc. as needed.

In addition, when light from the organic EL element 10 is taken out from the opposite side of the substrate body 62, external light is prevented from entering the TFT 63 formed on the substrate body 62 and changes in the electrical characteristics of the TFT 63 are prevented. For the purpose, it is preferable to use a light-shielding insulating film having light-shielding properties. In addition, the interlayer insulating film and the light-shielding insulating film can be used in combination. Examples of the light-shielding interlayer insulating film include those obtained by dispersing pigments or dyes such as phthalocyanine and quinaclonone in a polymer resin such as polyimide, color resists, black matrix materials, inorganic insulating materials such as Ni _x Zn _y Fe ₂ O _{4, and the} like. Can be mentioned. However, the present embodiment is not limited to these materials and forming methods.

In the present embodiment, unevenness is formed on the surface of the TFT 63 formed on the substrate body 62 and various wirings and electrodes, and the unevenness of the anode 13 and the cathode 20 in the organic EL element 10 due to the unevenness, organic EL There is a possibility that a layer defect, a short circuit between the anode 13 and the cathode 20, a decrease in breakdown voltage, or the like may occur. Therefore, it is desirable to provide the planarizing film 70 on the interlayer insulating film for the purpose of preventing these phenomena. The planarization film 70 used in the present embodiment can be formed using a known material, for example, an inorganic material such as silicon oxide, silicon nitride, or tantalum oxide, or an organic material such as polyimide, acrylic resin, or resist material. Etc. Examples of the method for forming the planarizing film 70 include a dry process such as a CVD method and a vacuum deposition method, and a wet process such as a spin coating method, but the present embodiment is not limited to these materials and the forming method. . Further, the planarization film 70 may have a single layer structure or a multilayer structure.

As shown in FIG. 9, the display device 60 of the present embodiment includes a pixel portion 72 formed on a light source side substrate 61, a gate signal side drive circuit 74, a data signal side drive circuit 73, a signal wiring 75, and a current supply. A line 76, a flexible printed wiring board 77 (FPC) connected to the light source side substrate 61, and an external drive circuit 100 are provided.

The light source side substrate 61 according to the present embodiment is electrically connected to an external driving circuit 100 including a scanning line electrode circuit, a data signal electrode circuit, a power supply circuit, and the like through the FPC 77 in order to drive the organic EL element 10. ing. In the present embodiment, a switching circuit such as a TFT 63 is disposed in the pixel portion 72. A data signal side driving circuit 73 and a gate signal side driving circuit 74 for driving the organic EL element 10 are connected to wirings such as a data line 69 and a gate line 65 to which the TFT 63 and the like are connected. An external drive circuit 100 is connected to the data signal side drive circuit 73 and the gate signal side drive circuit 74 via a signal wiring 75. In the pixel portion 72, a plurality of gate lines 65 and a plurality of data lines 69 are arranged, and a TFT 63 is arranged at an intersection of the gate lines 65 and the data lines 69.

The organic EL element 10 according to this embodiment is driven by a voltage-driven digital gradation method as shown in FIG. 10, for example. That is, two TFTs, a switching TFT 78 and a driving TFT 79 (63), are arranged for each pixel, and the contact hole 71 in which the driving TFT 79 (TFT 63) and the anode 13 of the organic EL element 10 are formed in the planarization layer 70. It is electrically connected via. Further, a capacitor (not shown) for making the gate potential of the driving TFT 79 constant in one pixel is disposed so as to be connected to the gate electrode of the driving TFT 79. A planarizing layer 70 is formed on the

TFTs

78 and 79.
However, the present embodiment is not particularly limited to these, and the driving method may be the voltage-driven digital gradation method described above or the current-driven analog gradation method. The number of TFTs is not particularly limited, and the organic EL element 10 may be driven by the two TFTs described above. For the purpose of preventing variations in TFT characteristics (mobility and threshold voltage), The organic EL element 10 may be driven using two or more TFTs having a built-in compensation circuit therein.

Also in the present embodiment, the same effect as that of the first embodiment can be obtained such that the light emitted from the phosphor layer 6 can be efficiently taken out of the substrate.
In particular, in the present embodiment, since the active matrix driving type light source side substrate 61 is employed, a display device having excellent display quality can be realized. In addition, the light emission time of the organic EL element 10 can be extended as compared with passive driving, and the driving current for obtaining desired luminance can be reduced, so that the power consumption can be reduced. Further, since the light is extracted from the opposite side (phosphor substrate side) of the light source side substrate 61, the light emitting region can be expanded regardless of the formation region of the TFT and various wirings, and the aperture ratio of the pixel is increased. Can do.

[Third Embodiment]
Hereinafter, a third embodiment will be described with reference to FIG.
The display device of this embodiment is a configuration example in which a liquid crystal element is inserted between a phosphor substrate and a light source.
FIG. 11 is a cross-sectional view showing the display device of this embodiment. In FIG. 11, the same reference numerals are given to the same constituent elements as those in FIG. 1A used in the first embodiment, and the description thereof will be omitted.

As shown in FIG. 11, the display device 80 of the present embodiment includes a phosphor substrate 2, a light source side substrate 81 (organic EL element substrate) including an organic EL element as the excitation light source 4, and a liquid crystal element 82. I have. The configuration of the phosphor substrate 2 is the same as that of the first embodiment, and a description thereof will be omitted. The laminated structure of the light source side substrate 82 is the same as that shown in FIG. 1B in the first embodiment. However, in the first embodiment, drive signals are individually supplied to the organic EL elements corresponding to each pixel, and each organic EL element is controlled to emit light and not emit light independently. On the other hand, in this embodiment, the organic EL element 83 is not divided for each pixel and functions as a planar light source common to all the pixels. The liquid crystal element 82 is configured to be able to control the voltage applied to the liquid crystal layer for each pixel using a pair of electrodes, and to control the transmittance of light emitted from the entire surface of the organic EL element 83 for each pixel. . In other words, the liquid crystal element 82 has a function as an optical shutter that selectively transmits light from the light source side substrate 81 for each pixel.

As the liquid crystal element 82 of the present embodiment, a known liquid crystal element can be used. For example, the liquid crystal element 82 includes a pair of

polarizing plates

84 and 85,

electrodes

86 and 87,

alignment films

88 and 89, and a substrate 90. The liquid crystal 91 is sandwiched between the

alignment films

88 and 89. Further, one optically anisotropic layer is disposed between the liquid crystal cell and one

polarizing plate

84, 85, or the optically anisotropic layer is disposed between the liquid crystal cell and both

polarizing plates

84, 85. 2 may be arranged. The type of liquid crystal cell is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include TN mode, VA mode, OCB mode, IPS mode, and ECB mode. The driving method of the liquid crystal element 82 may be passive driving or active driving using a switching element such as a TFT.

Also in the present embodiment, the same effect as that of the first embodiment can be obtained such that the light emitted from the phosphor layer 6 can be efficiently taken out of the substrate.
In the case of this embodiment, the power consumption can be further reduced by combining the pixel switching by the liquid crystal element 82 and the light source side substrate 81 functioning as a planar light source.

[Example of electronic equipment]
Examples of the electronic device including the display device of the embodiment include a mobile phone shown in FIG. 12A and a television receiver shown in FIG. 12B.
A cellular phone 127 shown in FIG. 12A includes a main body 128, a display unit 129, an audio input unit 130, an audio output unit 131, an antenna 132, an operation switch 133, and the like, and the display device of the above embodiment is used as the display unit 129. It has been.
A television receiver 135 illustrated in FIG. 12B includes a main body cabinet 136, a display unit 137, a speaker 138, a stand 139, and the like, and the display device of the embodiment is used for the display unit 137.
In such an electronic device, since the display device of the above-described embodiment is used, an electronic device with low power consumption and excellent display quality can be realized.

The technical scope in the aspect of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the aspect of the present invention.
For example, the display device described in the embodiment preferably includes a polarizing plate on the light extraction side. As the polarizing plate, a combination of a conventional linear polarizing plate and a λ / 4 plate can be used. By providing such a polarizing plate, external light reflection from the electrode of the display device or external light reflection on the surface of the substrate or the sealing substrate can be prevented, and the contrast of the display device can be improved. . In addition, specific descriptions regarding the shape, number, arrangement, material, formation method, and the like of each component of the phosphor substrate and the display device are not limited to the above-described embodiments, and can be appropriately changed.

Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the embodiments of the present invention are not limited to these examples.

(Comparative example)
A phosphor substrate of a comparative example with respect to the phosphor substrate of the example will be described with reference to FIGS. 13A and 13B. FIG. 13A is a side view of the phosphor substrate. FIG. 13B is a plan view of the phosphor substrate.
As the substrate 101, a square glass having a thickness of 0.7 mm was used. After washing with water, pure water ultrasonic cleaning 10 minutes, acetone ultrasonic cleaning 10 minutes, and isopropyl alcohol vapor cleaning 5 minutes were performed, followed by drying at 100 ° C. for 1 hour.
Next, green phosphor layers 102 having a thickness of 50 μm were formed on the substrate 101 at the four corners of the substrate 101.

Here, the green phosphor layer 102 is formed by first adding 30 g of green phosphor (Ba ₂ SiO ₄ : Eu ²⁺ ) particles having an average particle diameter of 4 μm and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol, followed by stirring with a disperser. The green phosphor forming coating solution was prepared by mixing.
Next, the prepared green phosphor forming coating solution was applied by pattern printing on the substrate 101 with a width of 100 μm and a pitch of 160 μm. Subsequently, it was heated and dried in a vacuum oven (200 ° C., 10 mmHg) for 4 hours to form a green phosphor layer 102 having a refractive index of 2.0, and a phosphor substrate 103 as a comparative example was completed.

Example 1
Example 1 will be described with reference to FIGS. 14A and 14B. In the present embodiment, an example in which the phosphor layer has a phosphor concentration gradient and the refractive index is adjusted will be described. FIG. 14A shows a side view of the phosphor substrate. FIG. 14B shows a plan view of the phosphor substrate during manufacture and a plan view of the completed phosphor substrate.
Using the glass substrate 101 cleaned and dried in the same manner as in the comparative example, green phosphor layers 104 were formed at the four corners of the substrate 101.
The green phosphor layer 104 is formed by first using Ba ₂ SiO ₄ : Eu ²⁺ particles having an average particle diameter of 4 μm as the green phosphor, and using 20 g of the green phosphor (Ba ₂ SiO ₄ : Eu ²⁺ ) particles and polyvinyl alcohol. 30 g of a 10 wt% aqueous solution was added and stirred and mixed by a disperser to prepare a green phosphor forming coating solution.
Next, the prepared green phosphor forming coating solution was applied by pattern printing on the substrate 101 with a width of 100 μm and a pitch of 160 μm. Then, it heat-dried for 4 hours in vacuum oven (200 degreeC, 10 mmHg conditions), and formed the green fluorescent substance layer 104a with a refractive index of 1.6 with a film thickness of 25 micrometers as shown to FIG. 14B.

Next, 30 g of the green phosphor (Ba ₂ SiO ₄ : Eu ²⁺ ) particles and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol were added, and the mixture was stirred and mixed by a disperser to prepare a green phosphor forming coating solution.
Thereafter, the prepared green phosphor-forming coating solution was applied by pattern printing onto the green phosphor layer 104a with a width of 100 μm and a pitch of 160 μm. Then, it heat-dried for 4 hours in vacuum oven (200 degreeC, 10 mmHg conditions), and formed the green fluorescent substance layer 104b of refractive index 2.0 with a film thickness of 25 micrometers as shown to FIG. 14B. Thereby, a green phosphor layer 104 having a two-layer structure with a thickness of 50 μm was formed, and the phosphor substrate 105 as Example 1 was completed.

Next, the surface of the green phosphor 104 of the phosphor substrate 105 thus produced was irradiated with light having a wavelength of 450 nm as excitation light from a blue LED, and a commercially available luminance meter (BM-7: Top Co., Ltd.) was irradiated. The brightness of light emitted from the substrate 101 was measured using a Contechno House Co., Ltd. Thereby, the luminance at 25 ° C. of the light emitted from the green phosphor 104 was measured. The luminance of the green phosphor 102 of the comparative example was measured in the same manner.
As a result, in Example 1, a brightness improvement of 1.2 times compared to the comparative example was observed. The following will be considered regarding the luminance improvement.

The excitation light incident side interface of the phosphor layers 102 and 104 exists between the phosphor layer and the air layer (first layer) having a refractive index of 1. The fluorescence extraction side interface of the phosphor layers 102 and 104 exists between the phosphor layer and glass (substrate 101) having a refractive index of 1.5.
Here, when considering the excitation light incident side interface, in Comparative Example 1 and Example 1, the refractive index of the phosphor layers 102 and 104 is higher than the refractive index of the air layer. Therefore, the total reflection loss of the excitation light does not occur in both. On the other hand, considering the fluorescence extraction side interface, the refractive index of the phosphor layer is higher than the refractive index of the glass (second layer) in both the comparative example and Example 1. Therefore, the higher the refractive index difference between the two, the greater the total reflection loss of fluorescence, resulting in poor light extraction efficiency.
The refractive index difference in the comparative example is 0.5, whereas the refractive index difference in Example 1 is 0.1.
Therefore, Example 1 is considered to have improved brightness because the light extraction efficiency is higher than that of the comparative example.

In Example 1, the phosphor layer 104 is composed of two

layers

104a and 104b. However, if the refractive index difference in the phosphor layer 104 is large, the phosphor layer 104 (the phosphor layer 104a and the phosphor layer 104b). Total reflection loss may occur at the interface). Therefore, in order to prevent the refractive index difference in the phosphor layer from becoming large, it is possible to gently change the refractive index difference in the phosphor layer by stacking three or more phosphor layers having different dispersion concentrations. preferable.

(Example 2)
Example 2 will be described with reference to FIGS. 15A and 15B. In this embodiment, an example in which the refractive index is adjusted by changing the particle size distribution of the phosphor in the phosphor layer will be described. FIG. 15A shows a side view of the phosphor substrate. FIG. 15B shows a plan view of the phosphor substrate during manufacture and a plan view of the completed phosphor substrate.
Using the glass substrate 101 cleaned and dried in the same manner as in the comparative example, green phosphor layers 106 were formed at the four corners of the substrate 101.
The green phosphor layer 106 is formed by first using Ba ₂ SiO ₄ : Eu ²⁺ particles having an average particle diameter of 500 nm as the green phosphor, and using 30 g of the green phosphor (Ba ₂ SiO ₄ : Eu ²⁺ ) particles and polyvinyl alcohol. 30 g of a 10 wt% aqueous solution was added and stirred and mixed by a disperser to prepare a green phosphor forming coating solution.
Next, the prepared green phosphor forming coating solution was applied by pattern printing on the substrate 101 with a width of 100 μm and a pitch of 160 μm. Then, it heat-dried for 4 hours in the vacuum oven (200 degreeC, 10 mmHg conditions), and as shown to FIG. 15B, the refractive index 1.6 green fluorescent substance layer 106a was formed with the film thickness of 25 micrometers.

Next, 30 g of green phosphor (Ba ₂ SiO ₄ : Eu ²⁺ ) particles having an average particle diameter of 4 μm and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol are added and stirred and mixed by a disperser to produce a green phosphor forming coating solution. did.
Thereafter, the prepared green phosphor-forming coating solution was applied by pattern printing onto the green phosphor layer 106a with a width of 100 μm and a pitch of 160 μm. Then, it heat-dried for 4 hours in vacuum oven (200 degreeC, 10 mmHg conditions), and as shown to FIG. 15B, the refractive index 2.0 green fluorescent substance layer 106b was formed with the film thickness of 25 micrometers. Thereby, a green phosphor layer 106 having a two-layer structure with a thickness of 50 μm was formed, and a phosphor substrate 107 as Example 2 was completed.

Next, the surface of the green phosphor 106 of the phosphor substrate 107 thus produced was irradiated with excitation light with light having a wavelength of 450 nm from a blue LED, and a commercially available luminance meter (BM-7: Top Co., Ltd.) was irradiated. The brightness of light emitted from the substrate 101 was measured using a Contechno House Co., Ltd. Thereby, the luminance at 25 ° C. of the light emitted from the green phosphor 106 was measured.
As a result, in Example 2, a luminance improvement of 1.3 times that of the comparative example was observed. The following will be considered regarding the luminance improvement.

The excitation light incident side interface of the phosphor layer 106 exists between the phosphor layer and the air layer (first layer) having a refractive index of 1 as in the first and comparative examples. The fluorescence extraction side interface of the phosphor layer 106 exists between the phosphor layer and glass having a refractive index of 1.5.
Here, considering the excitation light incident side interface, the refractive index of the phosphor layers 102 and 106 is higher than the refractive index of the air layer in both the comparative example and the example 2. Therefore, the total reflection loss of the excitation light does not occur in both cases. On the other hand, considering the fluorescence extraction side interface, the refractive index of the phosphor layer is higher than the refractive index of the glass (second layer) in both the comparative example and the example 2. Therefore, the higher the refractive index difference between the two, the greater the total reflection loss of fluorescence, resulting in poor light extraction efficiency.
The refractive index difference in the comparative example is 0.5, whereas the refractive index difference in Example 2 is 0.1.
Therefore, Example 2 is considered to have improved brightness because the light extraction efficiency is higher than that of the comparative example. Furthermore, since the particle size of the phosphor layer 106a is as small as nm order, light scattering is suppressed, and it is considered that the luminance is improved as compared with Example 1.

In Example 2, the phosphor layer 106 is composed of two

layers

106a and 106b. However, when the refractive index difference in the phosphor layer 106 increases, the phosphor layer 106 (the phosphor layer 106a and the phosphor layer 106b). Total reflection loss may occur at the interface). Therefore, in order to prevent the refractive index difference in the phosphor layer from increasing, the refractive index difference in the phosphor layer can be gradually changed by stacking three or more phosphor layers having different particle diameters. preferable.

(Example 3) [Example in which side scattering film and rear wavelength selective transmission / reflection film are employed]
Embodiment 3 will be described with reference to FIGS. 16A to 16H. In this embodiment, an example will be described in which a side scattering film and a backside wavelength selective transmission / reflection film are employed for a phosphor substrate. 16A to 16D are side sectional views showing steps of the method for manufacturing the phosphor substrate. 16E to 16H are plan views showing the steps of the method for manufacturing the phosphor substrate.
Using the glass substrate 101 cleaned and dried in the same manner as in Example 1, green phosphor layers 104 were formed at the four corners of the substrate 101.
First, a white resist pattern was formed in a forward taper shape with a 70 μm frame, a film thickness of 60 μm, and a pitch of 160 μm on the substrate 101, and a barrier 108 was produced as shown in FIGS. 16A and 16E.

Next, in the same manner as in Example 1, as shown in FIGS. 16B and 16F, the

phosphor layers

104a and 104b are formed in this order in the region surrounded by the barrier 108 by the dispenser method to form the phosphor layer 104. did.
Next, an acrylic resin was applied to the entire surface of the substrate 101 with a thickness of 20 μm by a spin coating method in order to minimize the occurrence of surface height imbalance on the obtained phosphor substrate. Subsequently, by heating at 120 ° C. for 30 minutes, a planarization layer 109 having a refractive index of 1.7 was formed as shown in FIGS. 16C and 16G.
Thereafter, six layers of titanium oxide (TiO2: refractive index = 2.30) and silicon oxide (SiO2: refractive index = 1.47) are alternately formed on the planarizing film 109 by the EB vapor deposition method. As shown in FIG. 16H, a wavelength selective transmission / reflection film 110 having a thickness of 2 μm was formed, and a phosphor substrate 111 as Example 3 was completed.

Next, light having a wavelength of 450 nm is emitted as excitation light from the blue LED to the surface of the green phosphor 104 from the wavelength selective transmission / reflection film 110 side of the phosphor substrate 111 thus manufactured, and a commercially available luminance meter ( The brightness of light emitted from the substrate 101 was measured using BM-7 (manufactured by Topcontec House Co., Ltd.). Thereby, the luminance at 25 ° C. of the light emitted from the green phosphor 104 was measured.
As a result, in Example 3, a brightness improvement of 2.5 times that in Example 1 was observed. The following will be considered regarding the luminance improvement.

Since the light emission from the phosphor layer 104 is isotropic, the fluorescent component directed to the side and back of the phosphor layer 104 is lost in the first embodiment. On the other hand, in Example 3, the fluorescent component directed to the side of the phosphor layer 104 is scattered by the barrier 108 and returns to the phosphor layer 104 so that it can be reused in the light extraction direction. Further, the fluorescent component toward the back surface of the phosphor layer 104 returns to the phosphor layer 104 by the wavelength selective transmission / reflection film 110 and can be reused in the light extraction direction. Therefore, by adopting the structure as in the third embodiment, the luminance can be further improved as compared with the first embodiment.

Note that the barrier 108 may be made of metal such as silver or aluminum using light reflection instead of light scattering. Further, the entire barrier 108 does not need to be made of a light scattering or light reflecting material, and it is sufficient that a light scattering or light reflecting film is formed at least on the surface of the barrier 108.
Further, the wavelength selective transmission / reflection film 110 may be formed of a metal thin film or an alloy thin film instead of a multilayer film.

(Example 4) [Example of adopting blue organic EL and phosphor system]
Embodiment 4 will be described with reference to FIGS. 17A to 18F. In this embodiment, an example in which a blue organic EL element and a phosphor system are employed will be described. 17A to 17D are side sectional views showing the steps of the method for manufacturing the phosphor substrate. FIG. 17E and FIG. 17H are plan views showing the steps of the method for manufacturing the phosphor substrate. 18A and 18C are side cross-sectional views showing the steps of the method for manufacturing the light source side substrate. 18D and 18F are plan views showing the steps of the method for manufacturing the light source side substrate.

Using the glass substrate 101 cleaned and dried in the same manner as in Example 1, the red phosphor layer 112, the green phosphor layer 113, and the blue scatterer layer 114 were formed, and the phosphor substrate 115 was formed.
First, a silver paste was formed into a forward taper pattern with a width of 70 μm, a film thickness of 60 μm, and a pitch of 160 μm on the substrate 101 by a screen printing method, and a reflection barrier 116 was produced as shown in FIGS. 17A and 17E.
Next, a red phosphor layer 112, a green phosphor layer 113, and a blue scatterer layer 114 were formed in the region surrounded by the reflection barrier 116 as follows.

In the formation of the red phosphor layer 112, first, 20 g of red phosphor (K ₅ Eu _2.5 (WO ₄ ) _6.25 ) particles having an average particle diameter of 4 μm and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol are added, and a disperser is added. The mixture was stirred and mixed to prepare a red phosphor forming coating solution.
Next, the prepared red phosphor forming coating solution was applied to a predetermined region between the reflection barriers 116 by a dispenser technique. Subsequently, it was heated and dried in a vacuum oven (200 ° C., 10 mmHg) for 4 hours, and a red phosphor layer 112a having a refractive index of 1.6 was patterned with a film thickness of 25 μm as shown in FIG. 17B.

Next, 30 g of the red phosphor (K ₅ Eu _2.5 (WO ₄ ) _6.25 ) particles and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol are added, and the mixture is stirred and mixed by a disperser to form a red phosphor forming coating. A liquid was prepared.
Next, the prepared red phosphor forming coating solution was applied onto the red phosphor layer 112a by a dispenser method. Then, it heat-dried for 4 hours in vacuum oven (200 degreeC, 10 mmHg conditions), and formed the red fluorescent substance layer 112b with a refractive index of 2.0 with the film thickness of 25 micrometers. As a result, a red phosphor layer 112 having a two-layer structure having a thickness of 50 μm was formed as shown in FIGS. 17B and 17F.

Next, in the formation of the green phosphor layer 113, first, 20 g of green phosphor (Ba ₂ SiO ₄ : Eu ²⁺ ) particles having an average particle diameter of 4 μm and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol are added and stirred by a disperser. The green phosphor forming coating solution was prepared by mixing.
Next, the prepared green phosphor forming coating solution was applied to a predetermined region between the reflection barriers 116 by a dispenser method. Then, it heat-dried for 4 hours in vacuum oven (200 degreeC, 10 mmHg conditions), and as shown to FIG. 17C, the green phosphor layer 113a with a refractive index of 1.6 was pattern-formed by the film thickness of 25 micrometers.

Next, 30 g of the green phosphor (Ba ₂ SiO ₄ : Eu ²⁺ ) particles and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol were added, and the mixture was stirred and mixed by a disperser to prepare a green phosphor forming coating solution.
Next, the produced green phosphor forming coating solution was applied onto the green phosphor layer 113a by a dispenser method. Then, it heat-dried for 4 hours in vacuum oven (200 degreeC, 10 mmHg conditions), and formed the green fluorescent substance layer 113b with a refractive index of 2.0 with the film thickness of 25 micrometers. Thereby, as shown in FIGS. 17C and 17G, a red phosphor layer 112 having a two-layer structure having a thickness of 50 μm was formed.

Next, in the formation of the blue scatterer layer, first, 20 g of silica particles (refractive index: 1.65) having an average particle diameter of 1.5 μm and 30 g of a 10 wt% aqueous solution of polyvinyl alcohol are added and stirred and mixed by a disperser. Thus, a coating liquid for forming a blue scatterer layer was prepared.
Next, the prepared blue scatterer layer forming coating solution was applied to a predetermined region between the reflection barriers 116 by a dispenser technique. Then, it heat-dried for 4 hours in vacuum oven (200 degreeC, 10 mmHg conditions), and as shown to FIG. 17D FIG. 17H, the blue scatterer layer 114 of refractive index 1.6 was pattern-formed with the film thickness of 50 micrometers.
Thus, the phosphor substrate 115 was produced.

Next, using the glass substrate 101 cleaned and dried in the same manner as in Example 1, a light source side substrate using an organic EL element as the excitation light source 4 was formed.
First, a reflective electrode is formed on a glass substrate 101 having a thickness of 0.7 mm by a sputtering method so that silver has a thickness of 100 nm, and indium-tin oxide (ITO) has a thickness of 20 nm on the reflective electrode. A film was formed by sputtering, and a reflective electrode (anode) was formed as the first electrode 141 as shown in FIGS. 18A and 18D. The first electrode 141 was patterned in a stripe pattern with a width of 70 μm and a pitch of 160 μm by a conventional photolithography method.

Next, SiO ₂ is deposited to 200 nm on the substrate 101 by sputtering, and is patterned by a conventional photolithography method so as to cover only the edge portion of the first electrode 141 as shown in FIGS. 18B and 18E. 142 was formed. Here, the short side is covered with SiO ₂ by 5 μm from the end of the first electrode 141. This was washed with water, then subjected to pure water ultrasonic cleaning for 10 minutes, acetone ultrasonic cleaning for 10 minutes, and isopropyl alcohol vapor cleaning for 5 minutes, and dried at 120 ° C. for 1 hour.

Next, the substrate 101 is fixed to a substrate holder in a resistance heating vapor deposition apparatus, and the inside of the resistance heating vapor deposition apparatus is depressurized to a vacuum of 1 × 10 ⁻⁴ Pa or less to form an organic light emitting layer as shown in FIGS. 18C and 18F. An organic EL layer 143 containing was formed by resistance heating vapor deposition.
First, as a hole injection material, 1,1-bis-di-4-tolylamino-phenyl-cyclohexane (TAPC) was used, and a hole injection layer having a thickness of 100 nm was formed by resistance heating vapor deposition.
Next, N, N′-di-1-naphthyl-N, N′-diphenyl-1,1′-biphenyl-1,1′-biphenyl-4,4′-diamine (NPD) is used as a hole transport material. A hole transport layer having a thickness of 40 nm was formed by resistance heating vapor deposition.

Next, a blue organic light emitting layer (thickness: 30 nm) is formed on the hole transport layer. This blue organic light-emitting layer comprises 1,4-bis-triphenylsilyl-benzene (UGH-2) (host material) and bis [(4,6-difluorophenyl) -pyridinato-N, C2 ′] picolinate iridium (III ) (FIrpic) (blue phosphorescent light emitting dopant) was prepared by co-evaporation at a deposition rate of 1.5 Å / sec and 0.2 Å / sec.
Next, a hole blocking layer (thickness: 10 nm) was formed on the light emitting layer using 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).
Next, an electron transport layer (thickness: 30 nm) was formed on the hole blocking layer using tris (8-hydroxyquinoline) aluminum (Alq3).
Next, an electron injection layer (thickness: 0.5 nm) was formed on the electron transport layer using lithium fluoride (LiF).

Thereafter, a translucent electrode was formed as the second electrode 144. First, the substrate 101 was fixed in a metal deposition chamber. Next, a shadow mask for forming the second electrode 144 (a mask having an opening so that the second electrode 144 can be formed in a stripe shape having a width of 70 μm and a pitch of 160 μm in a direction opposite to the stripe of the first electrode 141. ) And the substrate 101, and magnesium and silver are co-deposited on the surface of the electron injection layer by a vacuum deposition method at a deposition rate of 0.1 Å / sec and 0.9 Å / sec, respectively. A pattern was formed (thickness: 1 nm). Furthermore, silver is formed in a desired pattern at a deposition rate of 1 mm / sec (thickness: 19 nm) for the purpose of enhancing the interference effect and preventing voltage drop due to wiring resistance at the second electrode 144. )did.

Thereby, the second electrode 144 is formed. Here, as an organic EL element, a microcavity effect (interference effect) appears between the reflective electrode (first electrode 141) and the semi-transmissive electrode (second electrode 144), and the front luminance can be increased. Light emission energy from the EL element can be more efficiently propagated to the phosphor layer. Similarly, the emission peak is adjusted to 460 nm and the half-value width is adjusted to 50 nm by the microcavity effect.

Next, an inorganic protective layer made of 3 μm of SiO _{2 is} patterned by plasma CVD from the edge of the display unit to the sealing area of 2 mm in the vertical and horizontal directions (not shown). The light source side substrate provided with the organic EL element was produced as described above.

Next, the light source side substrate (organic EL element substrate) produced as described above and the phosphor substrate 115 were aligned using an alignment marker formed outside the display unit. Prior to this, a thermosetting resin was applied to the phosphor substrate 115, and both substrates were brought into close contact with each other through the thermosetting resin, and cured by heating at 80 ° C. for 2 hours. This bonding step was performed in a dry air environment (water content: −80 ° C.) for the purpose of preventing deterioration of the organic EL due to water.
Finally, an organic EL display device was completed by connecting terminals formed in the periphery to an external power source.

Here, a blue light emitting organic EL is used as an excitation light source that can be arbitrarily switched by applying a desired current to a desired striped electrode from an external power source. By converting to red and green, isotropic light emission of red and green was obtained, and isotropic blue light emission could be obtained through the blue scatterer layer. In this way, full color display was possible, and a good image and an image with good viewing angle characteristics could be obtained.
In Example 4, the blue scatterer layer 114 is not formed by stacking layers having different scatterer particle concentrations, but naturally, layers having different scatterer particle concentrations are stacked to form a blue scatterer layer. May be.

(Example 5)
In this embodiment, an example in which an active drive blue organic EL element and a phosphor system are employed will be described. The phosphor substrate was produced in the same manner as in Example 4.
An amorphous silicon semiconductor film was formed on a 100 mm × 100 mm square glass substrate by PECVD. Subsequently, a polycrystalline silicon semiconductor film was formed by performing a crystallization treatment. Next, the polycrystalline silicon semiconductor film was patterned into a plurality of islands by using a photolithography method. Subsequently, a gate insulating film and a gate electrode layer were formed in this order on the patterned polycrystalline silicon semiconductor layer, and patterning was performed using a photolithography method.

Thereafter, the patterned polycrystalline silicon semiconductor film was doped with an impurity element such as phosphorus to form source and drain regions, and a TFT element was produced. Thereafter, a planarizing film was formed. The planarizing film was formed by laminating a silicon nitride film formed by PECVD and an acrylic resin layer in this order using a spin coater. First, after forming a silicon nitride film, the silicon nitride film and the gate insulating film were etched together to form a contact hole leading to the source or drain region, and then a source wiring was formed. Thereafter, an acrylic resin layer was formed, and a contact hole communicating with the drain region was formed at the same position as the contact hole of the drain region drilled in the gate insulating film and the silicon nitride film. Through the above steps, an active matrix substrate was completed. The function as a planarizing film is realized by an acrylic resin layer. Note that the capacitor for setting the gate potential of the TFT to a constant potential is formed by interposing an insulating film such as an interlayer insulating film between the drain of the switching TFT and the source of the driving TFT.

A driving TFT, a first electrode of a red light emitting organic EL element, a first electrode of a green light emitting organic EL element, and a first electrode of a blue light emitting organic EL element are provided on the active matrix substrate through the planarization layer. Contact holes were formed for electrical connection.
Next, the first electrode (anode) of each pixel is formed by sputtering so as to be electrically connected to the contact hole provided through the planarization layer connected to the TFT for driving each light emitting pixel. Formed. The first electrode was formed by laminating with a thickness of Al (aluminum) 150 nm and IZO (indium oxide-zinc oxide) 20 nm. Next, the first electrode was patterned into a shape corresponding to each pixel by a conventional photolithography method. Here, the area of the first electrode was set to 70 μm × 70 μm. In addition, the display portion formed on a 100 mm × 100 mm square substrate is 80 mm × 80 mm, and a 2 mm wide sealing area provided on the top, bottom, left and right of the display portion is provided. Each was provided with a 2 mm terminal lead-out part. On the long side, a 2 mm terminal lead-out portion was provided on the side to be bent.

Next, 200 nm of SiO ₂ was laminated on the first electrode by sputtering, and was patterned by a conventional photolithography method so as to cover the edge portion of the first electrode. Here, a structure in which four sides from the end of the first electrode by 10 μm are covered with SiO ₂ to form an edge cover.
Next, the active substrate was cleaned. As the cleaning of the active substrate, for example, acetone and IPA were used for ultrasonic cleaning for 10 minutes, and then UV-ozone cleaning was performed for 30 minutes.

Next, this substrate was fixed to a substrate holder in an in-line type resistance heating vapor deposition apparatus, and the pressure was reduced to a vacuum of 1 × 10 ⁻⁴ Pa or less. Each organic layer was formed.
First, as a hole injection material, 1,1-bis-di-4-tolylamino-phenyl-cyclohexane (TAPC) was used, and a hole injection layer having a thickness of 100 nm was formed by resistance heating vapor deposition.
Next, N, N′-di-1-naphthyl-N, N′-diphenyl-1,1′-biphenyl-1,1′-biphenyl-4,4′-diamine (NPD) is used as a hole transport material. A hole transport layer having a thickness of 40 nm was formed by resistance heating vapor deposition.
Next, a blue organic light emitting layer (thickness: 30 nm) was formed on the hole transport layer. This blue organic light-emitting layer comprises 1,4-bis-triphenylsilyl-benzene (UGH-2) (host material) and bis [(4,6-difluorophenyl) -pyridinato-N, C2 ′] picolinate iridium (III ) (FIrpic) (blue phosphorescent light emitting dopant) was prepared by co-evaporation at a deposition rate of 1.5 Å / sec and 0.2 Å / sec.
Next, a hole blocking layer (thickness: 10 nm) was formed on the light emitting layer using 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).
Next, an electron transport layer (thickness: 30 nm) was formed on the hole blocking layer using tris (8-hydroxyquinoline) aluminum (Alq3).
Next, an electron injection layer (thickness: 0.5 nm) was formed on the electron transport layer using lithium fluoride (LiF).

Thereafter, a semitransparent electrode was formed as the second electrode. First, the substrate was fixed to a metal deposition chamber. Next, the shadow mask for forming the second electrode (a mask having an opening so that the second electrode can be formed in a stripe shape having a width of 2 mm in a direction opposite to the stripe of the first electrode) and the substrate are aligned. Then, on the surface of the electron injection layer, magnesium and silver are formed in a desired pattern by co-evaporation at a deposition rate of 0.1 Å / sec and 0.9 Å / sec by vacuum evaporation, respectively (thickness: 1 nm) )did. Furthermore, silver is formed in a desired pattern (thickness: at a deposition rate of 1 Å / sec) for the purpose of emphasizing the interference effect and preventing voltage drop due to wiring resistance at the second electrode. 19 nm). Thereby, the second electrode was formed. Here, as the organic EL element, a microcavity effect (interference effect) appears between the reflective electrode (first electrode) and the semi-transmissive electrode (second electrode), and the front luminance can be increased. Light emission energy from the EL element can be more efficiently propagated to the phosphor layer. Similarly, the emission peak is adjusted to 460 nm and the half-value width is adjusted to 50 nm by the microcavity effect.

Next, an inorganic protective layer made of SiO _{2 having} a thickness of 3 μm was formed by patterning from the edge of the display portion to a sealing area of 2 mm in the vertical and horizontal directions by a plasma CVD method. Thus, an active drive type organic EL element substrate was produced.
Next, the active drive type organic EL element substrate and the phosphor substrate produced as described above were aligned using an alignment marker formed outside the display unit. Prior to this, a thermosetting resin was applied to the phosphor substrate, and both substrates were brought into close contact with each other through the thermosetting resin, and cured by heating at 90 ° C. for 2 hours. The bonding step was performed in a dry air environment (water content: −80 ° C.) for the purpose of preventing deterioration of the organic EL due to water.

Next, a polarizing plate was attached to the substrate in the light extraction direction to complete an active drive organic EL.
Finally, the terminal formed on the short side is connected to the power supply circuit via the source driver, and the terminal formed on the long side is connected to the external power supply via the gate driver, so that 80 mm × 80 mm An active drive type organic EL display having the display part of FIG.
Here, a blue light emitting organic EL is used as an excitation light source that can be arbitrarily switched by applying a desired current to each pixel from an external power source, and red light and green light are emitted from blue light in a red phosphor layer and a green phosphor layer, respectively. And isotropic light emission of red and green was obtained, and isotropic blue light emission could be obtained through the blue scatterer layer. In this way, full color display was possible, and a good image and an image with good viewing angle characteristics could be obtained.

(Example 6)
In this embodiment, an example in which a blue LED and a phosphor system are employed will be described. The phosphor substrate was produced in the same manner as in Example 4.
Using TMG (trimethylgallium) and NH ₃ , a buffer layer made of GaN was grown to a thickness of 60 nm on the C surface of the sapphire substrate set in the reaction vessel at 550 ° C. Next, the temperature was raised to 1050 ° C., and an n-type contact layer made of Si-doped n-type GaN was grown to a thickness of 5 μm using SiH ₄ gas in addition to TMG and NH ₃ . Subsequently, TMA (trimethylaluminum) was added to the source gas, and a second cladding layer made of a Si-doped n-type Al0.3Ga0.7N layer was grown at a thickness of 0.2 μm at 1050 ° C.

Next, the temperature is lowered to 850 ° C., and the first n-type cladding layer made of Si-doped n-type In _0.01 Ga _0.99 N is made 60 nm using TMG, TMI (trimethylindium), NH ₃ and SiH _4. It was made to grow with the film thickness.
Subsequently, an active layer made of non-doped In0.05Ga0.95N was grown at a thickness of 5 nm at 850 ° C. using TMG, TMI, and NH 3. Further, CPM (cyclopentadienyl magnesium) is newly used in addition to TMG, TMI, and NH _3, and a first p-type cladding layer made of Mg-doped p-type In _0.01 Ga _0.99 N at 850 ° C. has a thickness of 60 nm. It was made to grow with the film thickness.
Next, the temperature is raised to 1100 ° C., and a second p-type cladding layer made of Mg-doped p-type Al _0.3 Ga _0.7 N is grown to a thickness of 150 nm using TMG, TMA, NH ₃ , and CPMg. I let you.

Subsequently, using TMG, NH ₃ and CPMg at 1100 ° C., a p-type contact layer made of Mg-doped p-type GaN was grown to a thickness of 600 nm. After the above operation was completed, the temperature was lowered to room temperature, the wafer was taken out of the reaction vessel, and the wafer was annealed at 720 ° C. to reduce the resistance of the p-type layer. Next, a mask having a predetermined shape was formed on the surface of the uppermost p-type contact layer, and etching was performed until the surface of the n-type contact layer was exposed. After the etching, a negative electrode made of titanium (Ti) and aluminum (Al) was formed on the surface of the n-type contact layer, and a positive electrode made of nickel (Ni) and gold (Au) was formed on the surface of the p-type contact layer. After electrode formation, the wafer is separated into 350 μm square chips, and the LED chip thus prepared is fixed with a UV curable resin on a substrate on which wiring for connecting to a separately prepared external circuit is formed, The chip and the wiring on the substrate were electrically connected to produce a light source substrate composed of a blue LED.

Next, the light source substrate and the phosphor substrate produced as described above were aligned with an alignment marker formed outside the display unit. Prior to this, a thermosetting resin was applied to the phosphor substrate, and both substrates were brought into close contact with each other through the thermosetting resin, and cured by heating at 80 ° C. for 2 hours. The bonding step was performed in a dry air environment (water content: −80 ° C.).
Finally, the LED display device was completed by connecting terminals formed in the periphery to an external power source.

Here, a blue LED is used as an excitation light source that can be arbitrarily switched by applying a desired current to a desired striped electrode from an external power source, and the red phosphor layer and the green phosphor layer emit light from blue light in red, By converting to green, isotropic light emission of red and green was obtained, and isotropic blue light emission could be obtained through the blue scatterer layer. In this way, full color display was possible, and a good image and an image with good viewing angle characteristics could be obtained.

The embodiment of the present invention can provide a display device with a simple structure and low power consumption.

DESCRIPTION OF

SYMBOLS

1, 25, 30, 35, 50, 60, 80 ... Display device, 2, 26, 31, 115 ... Phosphor substrate, 3, 27, 36, 51, 61, 81 ... Light source side substrate, 4 ... Excitation light source, 5 ... substrate (second layer), 6, 6R, 6G, 6B ... phosphor layer, 6a ... excitation light incident side interface, 6b ... fluorescence extraction side interface, 7 ... flattening layer (first layer), 10 83 ... Organic EL element, 82 ... Liquid crystal element

Claims

A phosphor layer that has an excitation light incident surface and a fluorescence extraction surface, and emits fluorescent light by excitation light incident through the excitation light incident surface;
A first layer in contact with the excitation light incident surface;
A second layer in contact with the fluorescence extraction surface,
The phosphor layer is configured such that the refractive index na in the vicinity of the excitation light incident surface is smaller than the refractive index n1 of the first layer,
The phosphor layer has an absolute value | n1-na | of the difference between the refractive index na of the phosphor layer and the refractive index n1 of the first layer in the vicinity of the excitation light incident surface, in the vicinity of the fluorescence extraction surface. Refractive index distribution between the excitation light incident surface and the fluorescence extraction surface so as to be smaller than the absolute value | n1-nb | of the difference between the refractive index nb of the phosphor layer and the refractive index n1 of the first layer. A phosphor substrate configured to include:
The phosphor layer is configured such that a refractive index nb in the vicinity of the fluorescence extraction surface is larger than a refractive index n2 of the second layer,
The phosphor layer has an absolute value | n2-nb | of the difference between the refractive index nb of the phosphor layer and the refractive index n2 of the second layer in the vicinity of the fluorescence extraction surface, in the vicinity of the excitation light incident surface. Refractive index distribution between the excitation light incident surface and the fluorescence extraction surface so as to be smaller than the absolute value | n2-na | of the difference between the refractive index na of the phosphor layer and the refractive index n2 of the second layer. The phosphor substrate according to claim 1, comprising:
The phosphor substrate according to claim 1, wherein the refractive index distribution of the phosphor layer continuously changes from the excitation light incident surface toward the fluorescence extraction surface.
The phosphor substrate according to claim 1, wherein the phosphor layer contains an inorganic phosphor.
The phosphor substrate according to claim 4, wherein a refractive index distribution of the phosphor layer is adjusted by a dispersion concentration of the inorganic phosphor in the phosphor layer.
The phosphor substrate according to claim 4, wherein a refractive index distribution of the phosphor layer is adjusted by a particle size distribution of the inorganic phosphor in the phosphor layer.
The phosphor substrate according to claim 1, wherein the phosphor layer is formed by any one of a screen printing method, an ink jet method, a dispenser method, and a nozzle coating method.
A display device comprising the phosphor substrate according to claim 1 and an excitation light source that emits the excitation light.
The display device according to claim 8, wherein the excitation light source is any one of a light emitting diode, an organic electroluminescence element, and an inorganic electroluminescence element.
Furthermore, it has a plurality of drive elements,
The display device according to claim 8, wherein the excitation light source includes a plurality of light emitting elements, and the plurality of light emitting elements are driven by the corresponding driving elements.
And a substrate on which the drive element is formed,
The phosphor layer is located between the second layer and the substrate;
The display device according to claim 10, wherein light from the phosphor layer is emitted through the second layer.
Furthermore, the liquid crystal device is provided between the excitation light source and the phosphor substrate, and can control the transmittance of light emitted from the excitation light source,
The display device according to claim 8, wherein the excitation light source is a planar light source that emits light from a light emission surface.
An excitation light incident surface and a fluorescence extraction surface; the excitation light incident through the excitation light incident surface generates fluorescence and emits light; and a phosphor layer;
A first layer in contact with the excitation light incident surface;
A second layer in contact with the fluorescence extraction surface,
The phosphor layer is configured such that a refractive index nb at the fluorescence extraction surface is larger than a refractive index n2 of the second layer,
The phosphor layer has an absolute value | n2-nb | of the difference between the refractive index nb of the phosphor layer and the refractive index n2 of the second layer in the vicinity of the fluorescence extraction surface, in the vicinity of the excitation light incident surface. Refractive index distribution between the excitation light incident surface and the fluorescence extraction surface so as to be smaller than the absolute value | n2-na | of the difference between the refractive index na of the phosphor layer and the refractive index n2 of the second layer. A phosphor substrate configured to include:
The phosphor substrate according to claim 13, wherein the refractive index distribution of the phosphor layer continuously changes from the excitation light incident surface toward the fluorescence extraction surface.
The phosphor substrate according to claim 13, wherein the phosphor layer contains an inorganic phosphor.
The phosphor substrate according to claim 15, wherein a refractive index distribution of the phosphor layer is adjusted by a dispersion concentration of the inorganic phosphor in the phosphor layer.
The phosphor substrate according to claim 15, wherein a refractive index distribution of the phosphor layer is adjusted by a particle size distribution of the inorganic phosphor in the phosphor layer.
The phosphor substrate according to claim 13, wherein the phosphor layer is formed by any one of a screen printing method, an ink jet method, a dispenser method, and a nozzle coating method.
A display device comprising the phosphor substrate according to claim 13 and the excitation light source.
The display device according to claim 19, wherein the excitation light source is any one of a light emitting diode, an organic electroluminescence element, and an inorganic electroluminescence element.
Furthermore, it has a plurality of drive elements,
The display device according to claim 19, wherein the excitation light source includes a plurality of light emitting elements, and the plurality of light emitting elements are driven by the corresponding driving elements.
And a substrate on which the drive element is formed,
The phosphor layer is located between the second layer and the substrate;
The display device according to claim 21, wherein light from the phosphor layer is emitted through the second layer.
Furthermore, the liquid crystal device is provided between the excitation light source and the phosphor substrate, and can control the transmittance of light emitted from the excitation light source,
The display device according to claim 19, wherein the excitation light source is a planar light source that emits light from a light emission surface.