JP2010186693A - Organic electroluminescent (el) display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent (EL) display device capable of suppressing coming around of an image due to an ambient light while reducing an increase in cost. <P>SOLUTION: The organic electroluminescent (EL) display device includes a reflecting electrode, an organic layer disposed on the reflecting electrode, a semi-permeable electrode disposed on the organic layer, and a beads-containing layer disposed on the semi-permeable electrode with the beads contained therein. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence (EL) display device.

  In recent years, active development of display devices using organic electroluminescence (EL) elements that are self-luminous, have high-speed response, wide viewing angle, high contrast, and can be made thinner and lighter. It has been broken.

  For example, according to Patent Document 1, an organic EL display element including a retroreflecting plate is disclosed in order to prevent reflection of an external light image. As an example of the retroreflecting plate, a configuration including a corner cube array or a microsphere is disclosed.

  However, it is necessary to make such a retroreflecting plate between the back side substrate as a base of the aluminum electrode. Moreover, since the surface of a retroreflection board becomes a foundation | substrate of an aluminum electrode, high smoothness is requested | required. For this reason, the manufacturing process becomes complicated, and there is a risk of increasing costs.

JP 2007-165331 A

  An object of the present invention is to provide an organic EL display device capable of suppressing the reflection of an image of external light while suppressing an increase in cost.

  According to one aspect of the present invention, a reflective electrode, an organic layer disposed on the reflective electrode, a semi-transmissive electrode disposed on the organic layer, and a bead disposed on the semi-transmissive electrode There is provided an organic EL display device comprising a bead-containing layer containing.

  According to another aspect of the present invention, the reflective electrode, the organic layer disposed on the reflective electrode, the semi-transmissive electrode disposed on the organic layer, and the semi-transmissive electrode are disposed. There is provided an organic EL display device comprising: a recursive layer that emits external light incident on the reflective electrode in a substantially incident direction.

  ADVANTAGE OF THE INVENTION According to this invention, the organic electroluminescent display apparatus which can suppress the reflection of the image of external light can be provided, suppressing the increase in cost.

FIG. 1 is a plan view schematically showing a configuration of an organic EL display device according to an aspect of the present invention. FIG. 2 is a schematic sectional view of a display panel including the organic EL element of the organic EL display device shown in FIG. FIG. 3 is a schematic cross-sectional view of a display panel having another configuration including the organic EL element of the organic EL display device shown in FIG. FIG. 4 is a plan view schematically showing the relationship between the triplet and the beads contained in the bead-containing layer.

  Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals are given to components that exhibit the same or similar functions, and duplicate descriptions are omitted.

  FIG. 1 is a plan view schematically showing a configuration of an organic EL display device.

  That is, the organic EL display device includes a display panel 1. The display panel 1 includes an array substrate 100 and a sealing substrate 200. The array substrate 100 includes a plurality of organic EL elements OLED arranged in a matrix in an active area 102 that displays an image. The sealing substrate 200 faces the organic EL element OLED of the array substrate 100. The array substrate 100 and the sealing substrate 200 are joined by a seal member 300 arranged in a frame shape so as to surround the active area 102.

  FIG. 2 is a cross-sectional view of the display panel 1 including the organic EL element OLED of the organic EL display device shown in FIG.

  The array substrate 100 includes an insulating substrate 101 such as glass, a switching transistor SW formed on the insulating substrate 101, an organic EL element OLED, and the like. An undercoat layer 111 is disposed on the insulating substrate 101. The undercoat layer 111 is made of, for example, silicon oxide. Such an undercoat layer 111 extends over substantially the entire active area 102.

  A semiconductor layer SC of the switching transistor SW is disposed on the undercoat layer 111. The semiconductor layer SC is made of, for example, polysilicon. In the semiconductor layer SC, a source region SCS and a drain region SCD are formed with a channel region SCC interposed therebetween.

  The semiconductor layer SC is covered with a gate insulating film 112. The gate insulating film 112 is disposed on the undercoat layer 111. The gate insulating film 112 is made of, for example, silicon nitride. Such a gate insulating film 112 extends over substantially the entire active area 102.

  On the gate insulating film 112, the gate electrode G of the switching transistor SW is disposed immediately above the channel region SCC. In this example, the switching transistor SW is a top-gate p-channel thin film transistor. The gate electrode G is covered with a passivation film 113. The passivation film 113 is disposed on the gate insulating film 112. The passivation film 113 is made of, for example, silicon nitride. Such a passivation film 113 extends over substantially the entire active area 102.

  On the passivation film 113, the source electrode S and the drain electrode D of the switching transistor SW are disposed. The source electrode S is in contact with the source region SCS of the semiconductor layer SC. The drain electrode D is in contact with the drain region SCD of the semiconductor layer SC.

  The source electrode S and the drain electrode D are covered with an organic insulating film 114. The organic insulating film 114 is disposed on the passivation film 113. Such an organic insulating film 114 extends over the entire active area 102.

  A pixel electrode PE constituting the organic EL element OLED is disposed on the organic insulating film 114. The pixel electrode PE is connected to the drain electrode D of the switching transistor SW. The pixel electrode PE corresponds to an anode in this example.

  The pixel electrode PE has a two-layer structure in which a reflective electrode PER and a transmissive electrode PET are stacked. That is, the reflective electrode PER is disposed on the organic insulating film 114. Further, the transmissive electrode PET is laminated on the reflective electrode PER. The reflective electrode PER is formed of a conductive material having light reflectivity, such as silver (Ag) or aluminum (Al). The transmissive electrode PET is made of a conductive material having optical transparency such as indium tin oxide (ITO), indium zinc oxide (IZO), and the like. Note that the pixel electrode PE is not limited to a two-layer structure, and may be a reflective electrode PER single layer. That is, the pixel electrode PE may be configured to include at least the reflective electrode PER.

  A partition wall PI is disposed on the organic insulating film 114. The partition wall PI is disposed along the periphery of the pixel electrode PE. The partition wall PI can be formed by patterning a resin material, for example.

  The organic layer ORG constituting the organic EL element OLED is arranged on the pixel electrode PE. The organic layer ORG includes at least a light emitting layer, and may further include a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and the like.

  The counter electrode CE constituting the organic EL element OLED is constituted by a semi-transmissive electrode. The counter electrode CE is disposed on the organic layer ORG. In this example, the counter electrode CE corresponds to a cathode. The counter electrode CE covers not only the organic layer ORG but also the partition wall PI. Such a counter electrode CE is made of, for example, magnesium or silver.

  A protective layer 115 is disposed on the counter electrode CE. The protective layer 115 is made of, for example, silicon oxide or silicon nitride. Such a protective layer 115 extends over the entire active area 102.

  A bead-containing layer 120 is disposed on the protective layer 115. The bead-containing layer 120 functions as a recursive layer that emits external light incident on the reflective electrode PER in a substantially incident direction. Such a bead-containing layer 120 is a layer formed by dispersing beads 122 in a resin layer 121, for example. The beads 122 are arranged in a dense state in the resin layer 121, and are arranged so as to form a single layer without the plurality of beads 122 being stacked in the thickness direction of the bead-containing layer 120. The beads 122 are substantially spherical bodies having a minute diameter, and are made of a light-transmitting material such as glass or plastic.

  The sealing substrate 200 is a light-transmitting insulating substrate such as glass or plastic. The sealing substrate 200 is disposed on the bead-containing layer 120. The sealing substrate 200 does not include a polarizing plate on the outer surface 200E, that is, the surface opposite to the surface facing the organic EL element OLED.

  According to the configuration of the present embodiment, the light emitted from the sealing substrate 200 side among the light generated in the organic EL element OLED is not absorbed by the polarizing plate, and thus the sealing substrate 200. Compared with a configuration in which a polarizing plate is provided on the outer surface 200E, the luminance of the organic EL element OLED can be improved. In addition, since the light generated in the organic EL element OLED is transmitted through the beads 122 of the bead-containing layer 120, the amount of light emitted in the observer direction is not significantly reduced by arranging the bead-containing layer 120, and the luminance The decline of is not a problem. In addition, the microcavity effect can be obtained by adjusting the thickness between the reflective electrode PER of the pixel electrode PE constituting the organic EL element OLED and the counter electrode CE which is a semi-transmissive electrode to the nano order, thereby improving the luminance. In addition, the color purity can be improved.

  Further, according to the configuration of the present embodiment, the external light incident from the sealing substrate 200 side toward the organic EL element OLED is reflected by the reflective electrode PER and then directed in the substantially incident direction by the bead-containing layer 120. Are emitted. That is, regular reflection of external light can be suppressed. For this reason, in the light emission state in which the organic EL element OLED generates light, the amount of specular reflection emitted in the observer direction out of the external light can be reduced, so that the contrast can be improved.

  A display panel 1 having the configuration shown in FIG. 2 and a display panel having a configuration in which the bead-containing layer is omitted from the configuration shown in FIG. 2 as a comparative example were prepared, and the contrast was measured under 10000 lx external light. When the contrast of the display panel of the comparative example is 1, the contrast of the display panel 1 of the present embodiment shown in FIG.

  Furthermore, according to the configuration of the present embodiment, by arranging the bead-containing layer 120, the image of external light is reflected not only in the light-emitting state but also in the non-light-emitting state where the organic EL element OLED does not generate light. Can be suppressed. For example, even when the display panel 1 displays black, reflection of an external light image is suppressed, so that a good black display can be realized.

  In the present embodiment, the above-described bead-containing layer 120 is bonded to the protective layer 115 and the sealing substrate 200. For example, a photosensitive resin material is used as an adhesive between the film-like bead-containing layer 120 in which beads 122 are dispersed in the resin layer 121 and the protective layer 115, and between the bead-containing layer 120 and the sealing substrate 200, respectively. Alternatively, the bead-containing layer 120 is bonded to both the protective layer 115 and the sealing substrate 200 by applying a thermosetting resin material and curing the resin material.

  As described above, the retroreflective effect of emitting external light in a substantially incident direction can be obtained by arranging and adhering the film-like bead-containing layer 120 between the organic EL element OLED and the sealing substrate 200. That is, the bead-containing layer 120 can be installed by a simple manufacturing process, and compared with a manufacturing process in which a retroreflector is formed on the array substrate 100, the process load is small and an increase in cost can be suppressed.

  In addition to the method described above, a photosensitive resin material or a thermosetting resin material in which beads 122 are dispersed is applied on the protective layer 115, and the resin material is placed in a state where the sealing substrate 200 is overlaid on the resin material. It is also possible to form the bead-containing layer 120 adhered to both the protective layer 115 and the sealing substrate 200 by curing.

  In any method, since the protective layer 115 is disposed between the bead-containing layer 120 and the counter electrode CE, the resin material used as the bead-containing layer 120 or the adhesive contacts the organic EL element OLED. do not do. For this reason, it is possible to prevent the organic EL element OLED from being contaminated by the resin layer 121 and the adhesive contained in the bead-containing layer 120 or moisture from entering.

  Between the bead-containing layer 120 and the reflective electrode PER, a protective layer 115 is disposed in addition to the transmissive electrode PET, the organic layer ORG, and the counter electrode CE that constitute the organic EL element OLED. As an example of the thickness, the total thickness of the transmissive electrode PET, the organic layer ORG, and the counter electrode CE of the organic EL element OLED is about 0.1 μm to 1.5 μm, the thickness of the protective layer 115 is about 50 nm, a bead-containing layer If the thickness of the resin material that bonds 120 to the protective layer 115 is about 1 μm, the distance from the reflective electrode PER to the lower surface of the bead-containing layer 120 is about 2.5 μm at the maximum. The distance between the reflective electrode and the bead-containing layer is sufficiently smaller than the diameter of the bead 122 when the average value of the diameter of the bead 122 is about 15 μm. For this reason, even if the reflective electrode PER and the bead-containing layer 120 are not in contact with each other, a recursive effect of emitting external light in a substantially incident direction can be obtained.

  When the beads 122 included in the bead-containing layer 120 are arranged so as to form a single layer, the effect of recursion becomes the greatest. Here, the single layer is a state in which the thickness of the bead-containing layer 120 is less than twice the average value of the diameter of the beads 122.

  In the present embodiment, the protective layer 115 between the counter electrode CE and the bead-containing layer 120 may be omitted without being limited to the example shown in FIG. That is, the bead-containing layer 120 may be bonded to the counter electrode CE.

  The bead-containing layer 120 may not be completely in close contact with the protective layer 115. In addition, when the protective layer is omitted, the bead-containing layer 120 may not be completely in close contact with the counter electrode CE. That is, even if a space such as an air layer is interposed between the bead-containing layer 120 and the protective layer 115 or between the bead-containing layer 120 and the counter electrode CE, external light is substantially incident in the incident direction. Although the retroreflecting effect of emitting is obtained, it is desirable that no space is interposed in order to efficiently emit light generated by the organic EL element OLED from the sealing substrate 200 side.

  In the display panel 1, a color filter formed of a colored resin material may be disposed on the surface of the sealing substrate 200 facing the organic EL element OLED. Such a color filter absorbs part of the external light. For this reason, the image displayed on the display panel 1 becomes less susceptible to the influence of external light, and the contrast can be further improved.

  Next, a modification of this embodiment will be described.

  FIG. 3 is a cross-sectional view of a display panel 1 having another configuration including the organic EL element OLED of the organic EL display device shown in FIG. In addition, about the same structure as the structure shown in FIG. 2, the same referential mark is attached | subjected and detailed description is abbreviate | omitted.

  The display panel 1 shown in FIG. 3 is different from the display panel 1 shown in FIG. 2 in that the bead-containing layer 120 is disposed on the outer surface 200E of the sealing substrate 200. The array substrate 100 includes an undercoat layer 111, a gate insulating film 112, a passivation film 113, and an organic insulating film 114 between the insulating substrate 101 and the organic EL element OLED. The switching transistor SW is disposed between the undercoat layer 111 and the gate insulating film 112 and is disposed between the semiconductor layer SC having the source region SCS, the channel region SCC, and the drain region SCD, and between the gate insulating film 112 and the passivation film 113. A gate electrode G, a source electrode S and a drain electrode D disposed between the passivation film 113 and the organic insulating film 114 are provided. The organic EL element OLED includes a pixel electrode having a reflective electrode PER disposed on the organic insulating film 114 and a transmissive electrode PET disposed on the reflective electrode PER, an organic layer ORG disposed on the pixel electrode PE, And the counter electrode CE which is a transflective electrode arrange | positioned on the organic layer ORG is provided. A protective layer 115 is disposed on the counter electrode CE. The sealing substrate 200 is disposed on the protective layer 115. The bead-containing layer 120 is disposed on the sealing substrate 200.

  Also in the configuration of such a modification, the same effect as the configuration shown in FIG. 2 can be obtained.

  In the modification shown in FIG. 3, the bead-containing layer 120 is bonded to the sealing substrate 200. For example, by applying a photosensitive resin material or a thermosetting resin material as an adhesive between the film-like bead-containing layer 120 and the sealing substrate 200, and curing the resin material, the bead-containing layer 120 is Bonded to the sealing substrate 200. Further, a bead-containing layer 120 adhered to the sealing substrate 200 is obtained by applying a photosensitive resin material or a thermosetting resin material in which beads 122 are dispersed on the sealing substrate 200 and curing the resin material. It is also possible to form

  Thus, since the sealing substrate 200 is interposed between the bead-containing layer 120 and the organic EL element OLED, the organic EL element OLED is not damaged in the process of forming the bead-containing layer 120, and the bead There is no restriction | limiting in particular about the method of forming the content layer 120. Further, since the resin material used as the bead-containing layer 120 or the adhesive does not contact the organic EL element OLED, the resin layer 121 contained in the bead-containing layer 120 or the organic EL element OLED due to the adhesive, or moisture Intrusion can be prevented.

  Note that the protective layer 115 between the counter electrode CE and the sealing substrate 200 may be omitted. Further, as illustrated in FIG. 3, the sealing substrate 200 may not be completely in close contact with the protective layer 115. When the protective layer 115 is omitted, the sealing substrate 200 may not be completely in close contact with the counter electrode CE. That is, a space such as an air layer may be interposed between the sealing substrate 200 and the protective layer 115 or a part between the sealing substrate 200 and the counter electrode CE. Note that the resin layer may be filled so that there is no space between the sealing substrate 200 and the protective layer 115 or between the sealing substrate 200 and the counter electrode CE.

  In the display panel 1, a color filter formed of a colored resin material may be disposed on the surface of the sealing substrate 200 facing the organic EL element OLED. Such a color filter absorbs part of the external light. For this reason, the image displayed on the display panel 1 becomes less susceptible to the influence of external light, and the contrast can be further improved.

  Next, the relationship between the diameter of the beads 122 contained in the bead-containing layer 120 and the pixel size will be described.

  FIG. 4 is a plan view schematically showing the relationship between the triplet T and the beads 122 included in the bead-containing layer 120. The triplet T is formed in a square shape having substantially the same length in the X direction and the Y direction. The triplet T includes a pixel PX1 that displays red, a pixel PX2 that displays green, and a pixel PX3 that displays blue. Here, it is assumed that each of the pixels PX1 to PX3 is substantially the same as the size of the pixel electrode PE or the reflective electrode PER constituting the organic EL element OLED.

  Each of the pixels PX1 to PX3 is formed in a rectangular shape extending in the Y direction. Further, in the example shown in FIG. 4, each of these pixels PX1 to PX3 has substantially the same dimensions, and each of the short sides along the X direction and each of the long sides along the Y direction. The length is approximately the same.

  The length of one side of the triplet T is, for example, 100 μm. In this case, the length of the long side of each pixel PX1 to PX3 is 100 μm, and the length of the short side of each pixel PX1 to PX3 is about 30 μm. For such a triplet T, the diameter of the beads 122 of the bead-containing layer 120 is smaller than the length of the short sides of the pixels PX1 to PX3. For example, the average value of the diameters of the beads 122 for the pixels PX1 to PX3 is about 10 to 20 μm.

  Thus, when the diameter of the bead 122 is smaller than the length of the short side of each of the pixels PX1 to PX3, the effect of recursiveness in which the external light is emitted substantially in the incident direction is high, and the external light is emitted when the incident light is incident. Since pixels of the same color pass through time, it is possible to prevent color misregistration and color mixing.

  The diameter of the beads 122 is desirably 10 μm or more and 100 μm or less. If the diameter of the beads 122 is smaller than 10 μm, it is difficult to arrange the beads 122 uniformly in the same plane, and the effect of recursion may be reduced. Moreover, when the diameter of the bead 122 exceeds 100 μm, the emission of light generated by the organic EL element OLED is hindered, and there is a risk of lowering the luminance. Further, when a color filter is interposed between the sealing substrate 200 and the organic EL element OLED, the bead-containing layer 120 is disposed between the color filter and the organic EL element OLED, so that the color is changed from the organic layer ORG. The distance to the filter is increased, and there is a possibility that color misregistration occurs in the viewing angle direction. For this reason, it is desirable that the diameter of the beads 122 be in the range of 10 to 100 μm.

  As described above, it is possible to provide an organic EL display device capable of suppressing the reflection of an image of external light while suppressing an increase in cost.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the spirit of the invention in the stage of implementation. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  The length of the triplet T shown in FIG. 4 has been described when the length of one side is 100 μm, the length of each pixel PX1 to PX3 is 100 μm, and the length of the short side of the pixel is 30 μm. The present invention is not limited to the above example.

  The material of the organic layer ORG of the organic EL element OLED may include a fluorescent material or a phosphorescent material.

DESCRIPTION OF SYMBOLS 1 ... Display panel 100 ... Array substrate 200 ... Sealing substrate 300 ... Sealing member OLED ... Organic EL element PE ... Pixel electrode (PER ... Reflective electrode PET ... Transmission electrode)
CE ... Counter electrode ORG ... Organic layer 115 ... Protective layer 120 ... Bead-containing layer (recursive layer) 121 ... Resin layer 122 ... Bead

Claims (5)

A reflective electrode;
An organic layer disposed on the reflective electrode;
A transflective electrode disposed on the organic layer;
A bead-containing layer disposed on the transflective electrode and containing beads;
An organic EL display device comprising: Furthermore, a protective layer disposed between the transflective electrode and the bead-containing layer,
The organic EL display device according to claim 1, further comprising: a sealing substrate disposed on the bead-containing layer.   The organic EL display device according to claim 1, further comprising a sealing substrate disposed between the transflective electrode and the bead-containing layer.   2. The organic EL display device according to claim 1, wherein a diameter of the beads of the bead-containing layer is smaller than a length of a short side of the reflective electrode. A reflective electrode;
An organic layer disposed on the reflective electrode;
A transflective electrode disposed on the organic layer;
A recursive layer disposed on the transflective electrode and emitting external light incident on the reflective electrode in a substantially incident direction;
An organic EL display device comprising:

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