JP2007273255A - Organic el display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a top emission type organic EL display device of high display quality. <P>SOLUTION: The top emission type organic EL display device comprises a first substrate provided with an organic EL element 7 with a reflecting lower electrode, a functional layer including an organic luminescent layer, and a light transmitting upper electrode laminated in this order, and a second substrate with a desiccant 2 formed on a surface facing a surface formed with the organic EL element 7, and emits light to the upper electrode 6 side. A physical adsorption type desiccant 2 and a color filter 4 are provided on the surface, facing the first substrate, of the second substrate, and the desiccant 2 and the color filter 4 or a black matrix 5 are arranged in this order from the second substrate toward the first substrate side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a top emission type organic EL display device, and more particularly to a technique for improving a viewing angle.

  Conventionally, there are two main types of sealing structures for top emission type organic EL display devices. A 1st structure is a structure sealed with resin, without providing sealing space. This structure was developed based on the idea of reducing the amount of moisture entering with a sealing resin without providing a desiccant. The second structure is an idea that a sealing space is provided by a sealing substrate, a desiccant is disposed in the space, and moisture that has entered the sealing space is absorbed.

  Among the second structures, Patent Document 1 discloses a top emission type organic EL display device using a transparent desiccant. In Patent Document 1, a chemisorption type transparent desiccant is used as the transparent desiccant.

JP 2003-338366 A

  The technology disclosed in Patent Document 1 does not disclose a color filter (hereinafter referred to as “CF”) or a black matrix (hereinafter referred to as “BM”). However, in the case of actually manufacturing a product-level top emission type organic EL display device using a sealing substrate, what kind of structure is optimal has not been studied.

  Therefore, we placed CF and BM in various places and examined them. First, CF and BM were arranged on the substrate in the light emitting direction, that is, outside the sealing substrate. When the screen was observed from the outside of the sealing substrate, a phenomenon called a shadowing in which the viewing angle was limited by BM occurred. This makes it impossible to take advantage of the great merits of a self-luminous organic EL display device.

  In addition, since the light emitting layer and the CF are separated from each other, colors may be mixed, and a large non-light emitting region is required between the pixels, and efficient light emission cannot be performed. In addition, when a chemical adsorption type desiccant is used, the chemical adsorption type desiccant is highly reactive, so if CF, BM, or an organic layer is formed on the desiccant, it will not be possible to secure a sufficient function as the desiccant. It was.

  One of the objects of the present invention is to provide a top emission type organic EL display device having an improved viewing angle.

  Another object of the present invention is to provide a top emission type organic EL display device which suppresses the functional deterioration of the desiccant during production.

  A first substrate including an organic EL element in which a reflective lower electrode, a functional layer including an organic light emitting layer, and a light transmissive upper electrode are sequentially laminated, and a surface on which the organic EL element is formed are opposed to each other. In a top emission type organic EL display device having a second substrate having a desiccant formed on the surface and emitting light to the upper electrode side, a physical adsorption type drying on the surface of the second substrate facing the first substrate An agent and CF or BM are included, and the desiccant, CF or BM are arranged in this order from the second substrate toward the first substrate.

  With this configuration, production can be performed without impairing the performance of the desiccant, and deterioration of display quality such as shadowing can be suppressed. Moreover, since CF can be brought close to the light emitting layer, color mixing can also be suppressed.

  According to the present invention, it is possible to provide a top emission type organic EL display device in which deterioration of display quality such as shadowing is suppressed.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described below in detail with reference to the drawings of the examples.

FIG. 1 is a conceptual cross-sectional view of an organic EL display device.
A TFT substrate 9 having an organic EL element 7 and a TFT forming layer 8 for driving the organic EL element 7 formed under the organic EL element 7, a color filter 4, a black matrix 5, and a desiccant layer 2. The sealing substrate 1 is bonded with a sealing material in a direction in which the components formed on the substrate face each other while the gas layer is held by the conductive beads 3.

  The organic EL element 7 has a structure in which a lower electrode, a functional layer including a light emitting layer, and an upper electrode 6 are laminated in this order. In the upper electrode 6, a plurality of light-transmitting fine particles of less than 10 μm are dispersedly arranged per pixel.

FIG. 2 shows a plan view of the organic EL display device.
An ultraviolet curable sealant, particularly a cation curable epoxy resin, is applied to a frame-shaped sealing seal region on the outer periphery of the pixel region 10 formed inside the TFT substrate 9. The pixel pattern and the pattern of the color filter 4 are aligned, bonded, and irradiated with ultraviolet rays to cure the sealing agent and seal it. The terminal portion 12 is connected to wiring connected to the inside and outside of the sealing region. An external wiring is connected to the terminal portion 12 to form an organic EL display device.

FIG. 3 shows a manufacturing process of the sealing substrate.
Since the transparent desiccant 2 has a subsequent process, it is of a physical adsorption type, and functions as a desiccant by removing water adsorbed by heating before sealing. Specifically, a compound solution containing colloidal silica is applied onto glass, dried, baked and gelled to form a coating film to obtain a desiccant capable of reversible adsorption and desorption of moisture. it can.

  On this transparent desiccant 2, a photosensitive resin solution in which the respective dyes for each color of red, blue, and green to be the color filter 4 are sequentially coated, exposed, developed, and baked to obtain red 4-1, green 4-4. 2, blue 4-3 filter was formed.

  Next, chromium oxide and metal chromium were formed in this order by sputtering, and resist coating, drying, exposure development, etching, and peeling were performed to form a black matrix 5 having conductivity. Thus, since the physical adsorption type desiccant is used, a color filter and a black matrix can be formed on the desiccant.

  When the sealing seal area shown in FIG. 2 is 5 mm or more, moisture penetrates along the desiccant. Therefore, it is preferable to remove the desiccant at the seal portion by etching. In this embodiment, the transparent desiccant 2 in the sealing seal area is removed by etching with hydrofluoric acid using the color filter 4 and the black matrix 5 as protective layers. When this etching is performed for a long time, the outermost peripheral edge of the black matrix 5 and the outermost peripheral edge of the transparent desiccant have substantially the same shape, but considering the function of the desiccant, the black matrix 5 It is formed so that the transparent desiccant 2 protrudes to the outside of the outermost periphery and between the sealing agent arrangement region.

  Next, the conductive beads 3 were dispersed on the black matrix 5 using a dispenser. This conductive bead 3 not only functions as a space between the TFT substrate 9 and the sealing substrate 1, but also the black matrix 5 functions as a bypass wiring via the conductive bead 3 because the black matrix 5 is conductive. It functions as an auxiliary wiring of the electrode 6 and has an effect of suppressing a voltage drop due to a high sheet resistance of the upper electrode 6.

Next, a process of forming the organic EL element 7 on the TFT substrate 9 will be described with reference to FIG.
First, a TFT is formed on a TFT substrate 9 which is a glass substrate. The TFT formation layer is roughly divided into two regions. One includes a pixel circuit that controls the emission intensity of the organic EL element 7 of each pixel for each pixel, and a peripheral circuit that controls the pixel circuit.

  The pixel circuit is connected to the lower electrode of the organic EL element 7. The lower electrode is formed for each pixel. The lower electrode is composed of two layers. The lower layer of the lower electrode is composed of a metal lower electrode 14 made of an aluminum-based alloy having high reflection characteristics. In the upper layer of the lower electrode, the transparent lower electrode 13 that functions as a protective antioxidant layer for the alloy layer mainly composed of aluminum is composed of an oxide of indium and tin (ITO).

  In addition, when an organic EL element can be formed immediately after forming the TFT, the transparent lower electrode 13 is formed after forming an alloy mainly composed of silver as the metal lower electrode 14 as well as aluminum having high reflectivity. It does not have to be.

  The organic EL element 7 emits 10 nm of a Li / trihydroxyquinoline aluminum 1: 1 co-deposited film as the electron injection layer 15 and 10 nm of the trihydroxyquinoline aluminum deposited film as the electron transport layer 16 on the transparent lower electrode 13. The layer 17 is 40 nm, the trianneal amine-based hole transport layer 18 is 10 nm, the hole injection layer 19 is deposited, and the vanadium pentoxide layer is deposited 10 nm. Thereafter, ZnO (zinc oxide) is sputtered as the first upper electrode 20. Formed. The light emitting layer 17 is separately coated with a red light emitting layer 17-1, a green light emitting layer 17-2, and a blue light emitting layer 17-3.

  At this time, the surface of the upper electrode 6 which is the uppermost layer of the organic EL element 7 is structured to scatter light. After forming the first upper electrode 20, the upper electrode 6 scatters the fine particles 21 on the first upper electrode 20, and forms the second upper electrode 22 thereon. The first upper electrode 20 is made of IZO and has a thickness of 30 to 100 nm. The second upper electrode 22 is made of IZO and has a thickness of 100 to 200 nm. The fine particles 21 are preferably several μm or less, preferably 1 μm or less and 50 nm or more in size, and materials such as silica, alumina powder, talc, and plastic powder can be used, but silica beads are preferable.

  The first upper electrode 20 described above is formed over the entire display area. As a result, a part of the fine particles 21 is buried in the second upper electrode 22.

  Next, the bonding process of the sealing substrate 1 shown in FIG. 4 and the TFT substrate 9 shown in FIG. 3 will be described. FIG. 5 shows a sealing process.

  In order to dehydrate the desiccant formed on the sealing substrate 1 before starting the bonding, the inside of the chamber was degassed, and then nitrogen gas was sealed and heated at 150 to 200 degrees for 10 to 20 minutes. . In other words, an inert gas dry atmosphere was created.

  A sealing agent 23 is applied to the sealing agent application region 11 in a dry atmosphere of an inert gas with respect to the sealing substrate 1, the TFT substrate 9 is aligned and bonded, and the sealing agent 11 is UV-cured. By sealing.

  As described above, a gas layer is held in the space supported by the conductive beads 3, and the nitrogen layer is sealed in the gas layer. Due to this gas layer, the light emitted from the upper electrode 6 enters a space having a refractive index of approximately 1, and from there through the color filter 4, the transparent desiccant 2, and the sealing substrate 1, the refractive index is theoretically 1 again. It will be released into some air. Since the refractive index of the intermediate member is higher than that of gas, light incident from the gas layer having a refractive index of approximately 1 in the sealed space passes through each interface at an angle greater than the critical angle. Don't be. If there is no space between the upper electrode 6 and the sealing substrate 1 and the light directly enters the glass, the light is guided in the glass, and the light extraction efficiency is greatly reduced.

  Further, a first substrate (TFT substrate) including an organic EL element in which a reflective lower electrode 13, a functional layer including an organic light emitting layer, and a light transmissive upper electrode are sequentially stacked, and an organic EL element are formed. In a top emission type organic EL display device that includes a second substrate (sealing substrate) having a desiccant formed on a surface opposite to the formed surface, and emits light to the upper electrode side. Since it has a physical adsorption type desiccant and a color filter or black matrix on the surface facing the substrate, the desiccant, color filter or black matrix are arranged in this order from the second substrate toward the first substrate. , Shadowing and color mixing can be suppressed.

  In addition, it is preferable in terms of light extraction efficiency that a gas layer is provided between the upper electrode and the color filter or black matrix. Further, as described above, since the solution containing colloidal silica is gelled as a desiccant to form a silica gel, the adsorption performance is also high.

FIG. 6 is a schematic cross-sectional view of the organic EL display device.
The difference from Example 1 is that the light emitting layer is a monochromatic light emitting layer. A monochromatic light emitting layer is used because it is difficult to finely coat the light emitting layer. This monochromatic light-emitting layer is a white light-emitting layer, which is realized by forming a hole transport layer, a hole injection layer, and an upper electrode after laminating red, green, and blue light-emitting layers in this order on the electron transport layer. ing.

  Instead of the color filter 4, a color conversion layer using a fluorescent material can also be used for colorization. In that case, a blue light emitting layer containing ultraviolet light is used as the light emitting layer. In this case, once the light is replaced with energy in the color conversion layer, it is replaced again with light, so that it becomes a waveguide mode in the color conversion layer or the sealing substrate, and the light extraction efficiency decreases, but the color conversion The light utilization efficiency up to the layer is improved. In addition, since the amount of light emission can be increased by the material of the light emitting layer, the luminance itself does not necessarily decrease.

FIG. 7 shows a schematic cross-sectional view of an organic EL display device.
The difference from Example 1 is that the conductive beads 3 are omitted. Since the black matrix 5 does not have to function as an auxiliary wiring, it does not necessarily have to be conductive. In a small size such that the short side of the outer shape is 50 nm or less, the current supplied to the lower electrode of each pixel is small, and the luminance gradient due to the resistance of the upper electrode 6 that is a common electrode does not occur so much. is not. Further, even without conductive beads, a gas layer that is a gap between the sealing substrate 1 and the TFT substrate 1 can be maintained.

FIG. 8 is a schematic sectional view of the organic EL display device.
The difference from the first embodiment is that the color filter is omitted. Although the function of the auxiliary wiring by the black matrix 5 and the conductive beads 3 is not different from that of the first embodiment, a bright organic EL display device having high brightness can be realized by the amount of omitting the color filter.

1 is a conceptual cross-sectional view of an organic EL display device. It is a top view of an organic electroluminescence display. It is a manufacturing-process figure of a sealing substrate. It is process drawing which forms an organic EL element on a TFT substrate. It is a figure which shows a sealing process. 1 is a conceptual cross-sectional view of an organic EL display device. 1 is a conceptual cross-sectional view of an organic EL display device. 1 is a conceptual cross-sectional view of an organic EL display device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sealing substrate, 2 ... Desiccant, 3 ... Conductive bead, 4 ... Color filter, 5 ... Black matrix, 6 ... Upper electrode, 7 ... Organic EL element 8 ... TFT formation layer, 9 ... TFT substrate

Claims (6)

A first substrate including an organic EL element in which a reflective lower electrode, a functional layer including an organic light emitting layer, and a light transmissive upper electrode are sequentially stacked;
A second substrate having a desiccant formed on the surface opposite to the surface on which the organic EL element is formed;
In the top emission type organic EL display device that emits light to the upper electrode side,
A physical adsorption type desiccant and a color filter on a surface of the second substrate facing the first substrate;
An organic EL display device, wherein the desiccant and the color filter are arranged in this order from the second substrate toward the first substrate. In claim 1,
An organic EL display device comprising a gas layer between the upper electrode and the color filter. A first substrate including an organic EL element in which a reflective lower electrode, a functional layer including an organic light emitting layer, and a light transmissive upper electrode are sequentially stacked;
A second substrate having a desiccant formed on the surface opposite to the surface on which the organic EL element is formed;
In the top emission type organic EL display device that emits light to the upper electrode side,
A physical adsorption type desiccant and a black matrix on a surface of the second substrate facing the first substrate;
An organic EL display device, wherein the desiccant and the black matrix are arranged in this order from the second substrate toward the first substrate. In claim 1,
An organic EL display device comprising a gas layer between the upper electrode and the black matrix. In claim 1 or claim 3,
The organic EL display device, wherein the desiccant is silica gel. A first substrate including an organic EL element in which a reflective lower electrode, a functional layer including an organic light emitting layer, and a light transmissive upper electrode are sequentially stacked;
A second substrate having a desiccant formed on the surface opposite to the surface on which the organic EL element is formed;
In the top emission type organic EL display device that emits light to the upper electrode side,
Between the surface of the second substrate facing the first substrate and the surface of the upper electrode of the organic EL element on the second substrate side, a physical adsorption type desiccant and a color filter are provided,
An organic EL display device, wherein the desiccant and the color filter are arranged in this order from the second substrate toward the first substrate.

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