JP6019372B2 - Light emitting device and light emitting panel - Google Patents

Description

  The present invention relates to a light emitting device such as an organic EL light emitting device and a light emitting panel.

In recent years, an organic EL light emitting panel in which a plurality of organic EL elements are arranged in a matrix direction on a substrate has been put to practical use as a light emitting display.
The organic EL light emitting panel is provided with a drive circuit (for example, including a TFT (Thin Film Transistor) element) on a substrate, an insulating layer is provided on the drive circuit, and a plurality of organic EL elements are arranged. The structure which becomes is known. Each organic EL element includes a first electrode (for example, an anode) on an insulating layer, and a functional layer including a light emitting layer made of an organic light emitting material on the first electrode, and a second electrode ( For example, it has a basic structure provided with a cathode.

In the functional layer, in addition to the light emitting layer, a hole (hole) injection layer, a hole (hole) transport layer, an electron injection layer, and an electron transport layer are laminated as necessary.
The organic EL element is a current driven type in which a voltage is applied between the first electrode and the second electrode at the time of driving, and light is emitted as a result of recombination of holes and electrons injected into the light emitting layer. It is a light emitting element. Thus, since each element performs self-light emission, it is excellent in visibility.

In an organic EL light emitting panel for full-color display, such an organic EL element forms RGB subpixels, and adjacent RGB subpixels are combined to form one pixel.
In general, a plurality of organic EL elements formed on a substrate are partitioned by a partition (bank) made of an insulating material, and the first electrode on the insulating layer is an independent electrode (pixel electrode) for each organic EL element. ). As described in Patent Document 1, the shape of the partition wall includes a lattice shape (box shape) and a stripe shape, and the partition wall is disposed between the plurality of first electrodes arranged on the substrate. .

  As one of the methods for forming a functional layer on the first electrode, a partition wall is formed on a substrate, and materials such as a hole transport layer, an electron block layer, and a light emitting layer constituting the functional layer, and an ink solvent There is a wet method in which a solution containing is applied by inkjet or the like (for example, Patent Document 1). According to this wet method, it is considered that the cost can be reduced in the production of a large panel from the viewpoint of good material utilization efficiency or the need for a vacuum device.

  In the case where the partition wall has a lattice shape (box shape), the ink is applied in units of pixels, and thus the thickness of the functional layer may vary from pixel unit to pixel unit due to variations in the coating amount. Therefore, Patent Document 1 describes that, in a stripe-shaped partition wall, variation in the thickness of the functional layer in the same stripe can be suppressed by suppressing variation in the coating amount in the same stripe.

  Patent Document 1 also discloses that a portion where the first electrodes are adjacent to each other is covered with a pixel restriction layer, and a functional layer is formed so as to cover the pixel restriction layer. Note that the “partition wall” and the “pixel restriction layer” are similar in that they separate adjacent pixels, but the partition wall has a function of separating the functional layers of adjacent pixels from each other. Has no function of separating such functional layers.

JP 2011-90910 A

  Here, in the edge region of the first electrode of the light emitting element, when there is no region where the partition wall or the pixel regulation layer and the first electrode overlap, edge light emission that emits abnormally may occur. In particular, when the first electrode is a pixel electrode, the light emitting layer is locally thinned at the edge portion of the pixel electrode (when the pixel electrode has a taper, the boundary between the flat portion and the inclined portion of the pixel electrode) (in FIG. 9). (A part indicated by symbol A). As a result, edge emission may occur due to the concentrated current flowing in the thinned region. In the case where the partition walls have a lattice shape, the edge light emission may be suppressed by covering the entire edge of the first electrode with the partition walls. However, in the case where the barrier ribs are striped, edge light emission as described above can occur in the edge portion of the first electrode that is not covered with the barrier ribs.

When edge light emission occurs in this manner, luminance unevenness occurs in the pixel, leading to deterioration of display characteristics. Therefore, improvement is desired.
Here, in order to suppress edge light emission, it is effective to cover the edge of the first electrode with an insulating layer or the like. However, when a new insulating layer is provided, the insulating layer is patterned in the manufacturing process. It is necessary and becomes a burden on manufacturing.

  The present invention has been made in view of the above problems, and is provided on a substrate, an insulating layer provided on the substrate, a first electrode provided on the insulating layer, and the first electrode. In a light-emitting element including a functional layer and a second electrode provided to face the first electrode through the functional layer, an object is to suppress edge light emission without increasing a manufacturing burden.

In order to solve the above problems, a light-emitting element according to one embodiment of the present invention includes a substrate, an insulating layer provided over the substrate, a first electrode provided over the insulating layer, and the first electrode. The region sandwiched between the first electrode and the second electrode in the functional layer includes a functional layer provided on the electrode and a second electrode provided to face the first electrode through the functional layer. It has a central part and a peripheral part outside the central part, and the central part of the functional layer is formed flat with a film thickness that emits light when a voltage is applied between the first electrode and the second electrode. In the functional layer, when the film thickness at which the light emission intensity when voltage is applied between the first electrode and the second electrode is ½ of the light emission intensity in the central part is D, in the peripheral part, The film thickness increases from the center side toward the outside until it reaches D, and on the outside of the position where the film thickness of the functional layer becomes D The thickness of the functional layer up to the edge of the area and the first electrode and the functional layer overlap is always set to be the above D, and the insulating layer, in a region where the peripheral portion is present, the An inclined surface inclined with respect to the substrate is formed, and the first electrode has an electrode inclined portion provided along the inclined surface.

Here, “the central portion of the functional layer is formed flat” means that the film thickness is almost constant throughout the central portion of the functional layer. That is, even if there is some variation in film thickness for each region in the central portion of the functional layer, it means that the variation width is smaller than that in the peripheral portion.
On the other hand, in the peripheral part of the functional layer, the film thickness increases outward from the center part side as described above.

  In the light-emitting element according to the above aspect, the region sandwiched between the first electrode and the second electrode in the functional layer is a region where an electric field is applied and a current flows when a voltage is applied between the first electrode and the second electrode. is there. Here, the central portion has a flat film thickness and is included in the light emitting region. In addition, since the thickness of the functional layer increases from the center side toward the outside in the peripheral part, the emission intensity when a voltage is applied between the first electrode and the second electrode decreases on the outside. The center side is a light emitting region, and outside the portion where the film thickness is D, the light emitting intensity is always a non-light emitting region having a light emitting intensity of ½ or less of the central portion.

  Therefore, even if the edge portion of the electrode is not covered with an insulating layer or the like, the edge portion side of the peripheral portion becomes a non-light emitting region until reaching the edge portion, so that the edge light emission is suppressed and the manufacturing process is burdened. There is no increase.

4 is a cross-sectional view schematically showing a configuration of display panel 100 according to Embodiment 1. FIG. 2 is a perspective view showing a schematic configuration of a display panel 100. FIG. 4 is an enlarged partial perspective view of the vicinity of a contact hole in the display panel 100. FIG. FIG. 3 is a diagram schematically showing a YZ cross-sectional structure of an organic EL element 20 in the display panel 100, and a diagram showing a film thickness and a light emission amount distribution of a functional layer 7. 4 is a diagram for explaining a method of manufacturing the display panel 100. FIG. It is sectional drawing which shows the structure of the display panel 100 concerning a modification. It is a figure which shows the whole structure of the display apparatus 200 concerning embodiment. It is an external appearance which shows an example of the television system using the display apparatus 200. FIG. It is a figure explaining the mechanism in which edge light emission produces in the organic EL element concerning a prior art example.

<Background to the Present Invention>
As a method for suppressing edge light emission of the light emitting element, for example, as disclosed in Patent Document 1, it is also effective to cover a portion where pixel electrodes arranged along a line-shaped partition are adjacent to each other with a pixel regulation layer. It is done.
However, in order to form the pixel restricting layer on the substrate, a film forming process for forming the film with the material of the pixel restricting layer and a process for patterning the formed film are required, which increases the number of manufacturing processes. Therefore, it is desired to suppress edge light emission without providing a process for forming such a pixel regulation layer.

Under such a background, the inventor gradually increases the film thickness of the functional layer in the peripheral part of the region sandwiched between the first electrode and the second electrode in the functional layer. The present inventors have found that the light emission intensity near the outer end portion can be reduced to make a non-light emitting region, and the present invention has been achieved.
In the present invention, the light emission amount in the functional layer is based on the film thickness D at which the light emission intensity is ½ of the light emission intensity in the central portion. A region where the intensity is ½ or less is regarded as a “non-light emitting region”.

<Aspect of the Invention>
In the display element of one embodiment of the present invention, a substrate, an insulating layer provided over the substrate, a first electrode provided over the insulating layer, and a function provided over the first electrode A region sandwiched between the first electrode and the second electrode in the functional layer includes a central portion and a central portion of the central portion. And a central portion of the functional layer is formed flat with a film thickness that emits light when a voltage is applied between the first electrode and the second electrode. When the film thickness at which the light emission intensity when a voltage is applied between the electrode and the second electrode is ½ of the light emission intensity at the central part is D, the film thickness of the functional layer is at the central part side in the peripheral part. From the position where the film thickness of the functional layer becomes D, the first electrode and the machine The thickness of the functional layer up to the edge of the region where the layers overlap is always set to be the above D. Note that the functional layer may be formed only of the light emitting layer, or may be formed by stacking a light emitting layer and a hole transport layer.

  In the light-emitting element according to the above aspect, the region sandwiched between the first electrode and the second electrode in the functional layer has the first electrode and the second electrode when a voltage is applied between the first electrode and the second electrode. This is a region in which an electric field is applied between and the current flows. Here, the central portion has a flat film thickness, and the film thickness is so thin as to emit light, so the central portion is included in the light emitting region. On the other hand, in the peripheral part, the thickness of the functional layer increases from the central part side toward the outside, so that the emission intensity when a voltage is applied between the first electrode and the second electrode is outside. The center side is a light emitting region, and outside the portion where the film thickness is D, the light emitting intensity is always a non-light emitting region whose emission intensity is ½ or less of the central portion.

Therefore, even if the edge portion of the electrode is not covered with an insulating layer or the like, there is no portion where the film thickness of the functional layer decreases until reaching the edge on the edge portion side of the peripheral portion. As a result, edge emission is suppressed. In addition, since it is not necessary to form a pixel regulation layer for suppressing edge emission, the burden on the manufacturing process does not increase.
In the functional layer, the film thickness at which the light emission intensity when a voltage is applied between the first electrode and the second electrode is ½ of the light emission intensity at the central part is almost twice the average film thickness at the central part. It is. That is, the average film thickness at the center is approximately ½ of D.

The display element may be configured as follows.
In the peripheral part of the functional layer, if the thickness of the functional layer is monotonously increased from the central part side toward the outside, the emission intensity gradually decreases from the central part side toward the outside, and the non-light emitting region Gradually shift to the light emitting area.
Here, “the film thickness increases monotonously from the center side to the outside” means that “there is no portion where the film thickness decreases from the center side to the outside”, that is, the position on the functional layer. It means that the film thickness d (x1) at x1 and the film thickness d (x2) at the position x2 outside the position x1 have a relationship of d (x1) ≦ d (x2). However, film thickness unevenness that occurs even when formed on a flat substrate is within an error range, and the error range is within 10% of the film thickness. In addition, the film thickness here is a set film thickness or an average film thickness.

  In the display panel of one embodiment of the present invention, a substrate, an insulating layer provided over the substrate, a plurality of first electrodes arranged in one direction along the surface of the insulating layer, A pair of line barrier ribs provided along both sides of the plurality of first electrodes arranged in a row, a functional layer provided on the plurality of first electrodes between the pair of line barrier ribs, and a plurality of layers via the functional layer Each region sandwiched between the first electrode and the second electrode in the functional layer includes a central portion in one direction and both of the central portion. And a central portion of the functional layer is formed flat with a film thickness that emits light when a voltage is applied between the first electrode and the second electrode. The emission intensity when a voltage is applied between one electrode and the second electrode is equal to the emission intensity at the center. When the film thickness to be / 2 is D, in the peripheral part, the film thickness of the functional layer increases from the central part side toward the outside until it reaches D, and on the outer side than the part where the film thickness becomes D. The film thickness of the functional layer was always set to be D or more until reaching the edge of the region where the first electrode and the functional layer overlap.

In the light-emitting panel of this aspect, similarly to the above light-emitting element, a non-light-emitting region is formed on the edge side of the peripheral part until it reaches the edge without covering the edge of the electrode with an insulating layer or the like. In addition, edge emission at the edge portion of the region sandwiched between the first electrode and the second electrode in the functional layer is suppressed, and the burden on the manufacturing process does not increase.
In this light emitting panel, the insulating layer is formed with an inclined surface inclined with respect to the substrate in a region where the peripheral portion exists, and the first electrode has an electrode inclined portion provided along the inclined surface. It may be.

Further, in this light emitting panel, when a contact hole that is a depression for connecting each first electrode and the TFT is formed in the insulating layer, the side wall surface of the contact hole is inclined in a tapered shape, and each first electrode is inclined. Each of the edges may be on the side wall surface of the corresponding contact hole.
Accordingly, when the functional layer is formed by a wet method, the thickness of the functional layer in the peripheral portion can be easily set as described above.

Here, the contact hole may be filled with the same material as that for forming the line partition wall.
Accordingly, when the functional layer is formed by a wet method, even if the amount of ink applied in the contact hole is small, the contact hole is filled with ink, so that the leveling is improved. In addition, since the line partition wall material can be embedded in the contact hole at the same time as the step of forming the line partition wall, the number of processes does not increase.

<Embodiment>
[Overall configuration of display panel 100]
The display panel 100 is an organic EL panel using an electroluminescence phenomenon of an organic material.
FIG. 1A is a partial sectional view schematically showing the configuration of the display panel 100, and FIG. 1B is a partial plan view of the display panel 100. FIG. 2 is a perspective view illustrating a schematic configuration of the display panel 100.

The display panel 100 is a top emission type in which a plurality of organic EL elements 20 are formed on a substrate 4. Fig.1 (a) has shown the cross section which cut | disconnected the arranged organic EL element 20 ... in the vertical direction (Y direction).
As shown in FIG. 1B, in this display panel 100, an organic EL element 20a that forms a blue subpixel, an organic EL element 20b that forms a green subpixel, and an organic EL element that forms a red subpixel. 20c are arranged in a matrix in the horizontal and vertical directions (XY directions).

The organic EL elements 20 of the same color are arranged in a line in the vertical direction (Y direction). One pixel is formed by the three organic EL elements 20a, 20b, and 20c adjacent in the horizontal direction (X direction).
One anode plate 5 is disposed in each organic EL element 20. Each anode plate 5 has a rectangular shape elongated in the vertical direction, and is formed in a region corresponding to each subpixel on the interlayer insulating film 3. Accordingly, in the display panel 100, a plurality of anode plates 5 are arranged for each color at intervals in the vertical direction (Y direction).

In FIG. 1B, the shaded area indicates the anode plate 5.
A line-shaped partition wall 6 is formed along both sides of the plurality of anode plates 5 arranged in the vertical direction.
A laminated structure of each layer in the display panel 100 is shown in FIG.
The TFT substrate 1 includes TFTs and wirings (not shown) for driving the organic EL elements 20a to 20c by an active matrix method on the main surface of the base substrate. The TFT includes an electrode (source-drain electrode) 2 that supplies current to the anode 5.

An interlayer insulating film 3 is formed on the TFT layer of the TFT substrate 1. In FIG. 1A, the TFT and wiring are not shown, and only the SD electrode 2 of the TFT is shown.
The base substrate of the TFT substrate 1 is alkali-free glass, soda glass, non-fluorescent glass, phosphate glass, borate glass, quartz, acrylic resin, styrene resin, polycarbonate resin, epoxy resin, polyethylene, polyester , Silicone resin, or insulating material such as alumina.

The interlayer insulating film 3 is made of an organic material having excellent insulating properties, such as polyimide, polyamide, acrylic, and siloxane resin material, and entirely covers the TFT layer of the TFT substrate 1.
The substrate 4 is a TFT substrate 1 on which an interlayer insulating film 3 is formed. An anode plate 5 and a partition wall 6 are formed on the substrate 4, and a functional layer 7 (hole transport) is formed on the anode plate 5. The layer 7a, the light emitting layer 7b), the cathode layer 8, and the sealing layer 9 are laminated in order to form the organic EL elements 20a, 20b, and 20c.

In FIG. 1B and FIG. 2, the functional layer 7, the cathode layer 8, and the sealing layer 9 are omitted.
[Configuration of anode plate 5, partition wall 6 and functional layer 7]
The anode plate 5 preferably has light reflectivity. In addition to Ag (silver), for example, Al (aluminum) or an Al alloy, APC (silver-palladium-copper alloy), ARA (silver-rubidium). -Based on metal materials such as gold alloy), MoCr (molybdenum and chromium alloy), NiCr (nickel and chromium alloy). On the upper surface of the metal layer, a hole injection layer is formed of a material such as molybdenum, tungsten, nickel, chromium, which is an inorganic material, or an oxide of an alloy of these metals, or PEDOT, which is an organic material. Yes.

  The partition 6 is made of an insulating organic material (for example, an acrylic resin, a polyimide resin, a novolac type phenol resin, etc.), and is formed so that at least the surface has liquid repellency. In addition, as a method for imparting liquid repellency to the partition wall 6, a method using a liquid repellent material among the above organic materials, a method of forming the partition wall 6 using a material that does not have liquid repellency, a fluorine plasma, or the like There is a method of performing the surface treatment. Each partition 6 has a line shape that is long in the vertical direction (Y direction) so as to pass between adjacent organic EL elements 20a, 20b, and 20c, and has a pitch in the horizontal direction (X direction) of the plurality of partition walls 6. Are equal pitches.

The partition wall width in the horizontal direction (X direction) of each partition wall 6 is uniform. Each partition wall 6 is formed so as to cover edge portions on both sides of the plurality of anode plates 5 arranged in the vertical direction, that is, edge portions extending in the vertical direction (Y direction) of the anode plates 5.
A functional layer 7 is formed in a region sandwiched between adjacent barrier ribs 6 so as to cover the anode plate 5. The functional layer 7 includes a hole injection layer (not shown) disposed immediately above the anode plate 5, a hole transport layer 7a, and a light emitting layer 7b disposed on the hole transport layer 7a.

Specific examples of the material of the hole transport layer 7a include 4,4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPB or α-NPD), N, N′-bis (3 And triarylamine compounds such as -methylphenyl)-(1,1'-biphenyl) -4,4'-diamine (TPD).
The anode plate 5 and the hole transport layer 7a preferably have a configuration in which a common material is used for the three-color organic EL elements 20a, 20b, and 20c. However, the present invention is not limited to this, and the anode plate 5 and the hole transport layer 7a may not be a material common to the three-color organic EL elements 20a, 20b, and 20c. The light emitting layer 7b is an organic EL element 20a, 20b, 20c of three colors, and is formed of a light emitting material that emits blue, green, and red light.

  Examples of the material of the light emitting layer 7b include oxinoid compounds, perylene compounds, coumarin compounds, azacoumarin compounds, oxazole compounds, oxadiazole compounds, perinone compounds, pyrrolopyrrole compounds, naphthalene compounds, anthracene compounds, fluorene compounds, fluoranthene compounds, tetracenes, and the like. Compound, pyrene compound, coronene compound, quinolone compound and azaquinolone compound, pyrazoline derivative and pyrazolone derivative, rhodamine compound, chrysene compound, phenanthrene compound, cyclopentadiene compound, stilbene compound, diphenylquinone compound, styryl compound, butadiene compound, dicyanomethylenepyran compound , Dicyanomethylenethiopyran compounds, fluorescein compounds, pyrylium compounds, thiapyrylium Compound, serenapyrylium compound, telluropyrylium compound, aromatic aldadiene compound, oligophenylene compound, thioxanthene compound, anthracene compound, cyanine compound, acridine compound, metal complex of 8-hydroxyquinoline compound, metal complex of 2-bipyridine compound, A fluorescent substance such as a complex of a Schiff salt and a group III metal, an oxine metal complex, or a rare earth complex can be given.

The cathode layer 8 is formed of a light transmissive material, for example, ITO, IZO (indium zinc oxide) or the like, and is formed so as to cover the light emitting layer 7b of the three-color organic EL elements 20a, 20b, and 20c.
A sealing layer 9 is provided on the cathode layer 8. The sealing layer 9 is made of a light transmissive material such as SiN (silicon nitride) or SiON (silicon oxynitride).

In the display panel 100 having such a configuration, the functional layer 7 is interposed between the anode plate 5 and the cathode layer 8 in each of the organic EL elements 20a, 20b, and 20c.
[Shape of interlayer insulating film 3, anode plate 5, functional layer 7]
The characteristics of the interlayer insulating film 3, the anode plate 5, and the functional layer 7 in the display panel 100 will be described in detail.

The interlayer insulating film 3 is a film having a flat surface over the entire panel. However, the contact hole 15 is provided between the anode plates 5 adjacent to each other in the vertical direction (Y direction), that is, between the adjacent organic EL elements 20. Is formed.
Each contact hole 15 is for electrically connecting a TFT provided on the TFT substrate 1 corresponding to each organic EL element 20 and the anode plate 5.

FIG. 3 is a partial perspective view in which the vicinity of the contact hole 15 in the display panel 100 is enlarged. In the drawing, the functional layer 7, the cathode layer 8, and the like are omitted.
As shown in FIG. 3, the contact hole 15 has a rectangular opening as shown in FIG. 1 (b), and its inner wall surface is a forward taper as shown in FIG. 1 (a) and FIG. The inclined surfaces 15a and 15c are inclined in the shape of a truncated pyramid having a larger hole diameter on the opening side than the bottom surface 15b. The bottom surface 15b of the contact hole 15 faces the SD electrode 2 of the TFT.

The inclination angles α1 and α2 of the inclined surfaces 15a and 15c with respect to the TFT substrate 1 may be a forward taper of less than 90 °, and the inclination angles α1 and α2 are preferably about 20 ° to 45 °.
The anode plate 5 includes a central portion 51 in the central portion in the vertical direction (Y direction), a portion extending from the central portion 51 in the vertical direction (Y direction) (the inclined portion 52 and the end portion 53), and the other. And an extending portion (inclined portion 54).

One inclined portion 52 is formed along the inclined surface 15a of the contact hole 15, and the subsequent end portion 53 is connected to the SD electrode 2 of the corresponding TFT at the bottom surface 15b of the contact hole 15, thereby the anode plate. 5 and the SD electrode 2 are electrically connected.
The edge of the end portion 53 exists in the contact hole 15.
The other inclined portion 54 is formed along the inclined surface 15 c of the adjacent contact hole 15, but is not connected to the SD electrode 2.

The edge of the inclined portion 54 is also present in the contact hole 15.
Since the contact hole 15 is formed in a rectangular shape in plan view as described above, the shapes of the inclined surfaces 15a and 15c and the bottom surface 15b are also rectangular, whereby the inclined portions 52 and end portions of the anode plate 5 are formed. 53 and the width | variety of the inclination part 54 are securable.
The contact hole 15 may have a shape other than a rectangle in plan view, for example, an oval shape or a circular shape. In this case, the inclined surfaces 15a and 15c are narrow on the bottom surface side of the contact hole 15. Become.

The functional layer 7 is formed on the anode plate 5 having the above-described shape by a wet method, and the thickness of the functional layer 7 is set in the vertical direction (Y direction) as follows.
FIG. 4 is a diagram schematically showing a YZ cross-sectional structure of the organic EL element 20 in the display panel 100, and a diagram showing the film thickness and light emission amount of the functional layer 7.
The shape and function of the functional layer 7 will be described with reference to FIG.

As described above, the functional layer 7 is disposed between the anode plate 5 and the cathode layer 8.
One organic EL element 20 has one region 70 in which the functional layer 7 is sandwiched between one anode plate 5 and one cathode layer 8. This region 70 is a region to which a voltage is applied when a voltage is applied between the anode plate 5 and the cathode layer 8.
In this one region 70, the functional layer 7 sandwiches the central portion 71 in contact with the central portion 51 (a flat portion parallel to the TFT substrate 1) of the anode plate 5 and the central portion 71 in the vertical direction. Thus, there is a peripheral portion 72 on one side and a peripheral portion 73 on the other side.

One peripheral portion 72 is a portion in contact with the inclined portion 52 and the end portion 53 of the anode plate 5, and the other peripheral portion 73 is a portion in contact with the inclined portion 54 of the anode plate 5.
The film thickness in the central portion 71 of the functional layer 7 is flat. That is, even if there is a slight variation in the film thickness for each region in the central portion 71, the film thickness d1 is kept substantially constant throughout the central portion 71.
In addition, the average film thickness d1 in the central portion 71 is relatively small so that a current sufficient to emit light flows when a voltage is applied between the anode plate 5 and the cathode layer 8 during driving.

On the other hand, in the peripheral portion 72, the thickness of the functional layer 7 in contact with the inclined portion 52 gradually increases from the central portion 71 side to the outside (in the direction opposite to the arrow Y) and is approximately twice or more the film thickness d1 in the central portion 71. It has become.
A point P1 in FIG. 4 is that the film thickness d2 of the functional layer 7 is twice the average film thickness d1 of the functional layer 7 in the central portion 71. This point P1 corresponds to a point where the emission intensity becomes the emission intensity in the central portion 71, that is, a point where the film thickness is approximately twice the average film thickness d1 of the central portion 71.

When a voltage is applied between the anode plate 5 and the cathode layer 8 at the time of driving, the current density is reduced at a portion where the film thickness is large in the region 70 sandwiched between the anode plate 5 and the cathode layer 8. Also, the emission intensity is reduced. This is because the light emission intensity (light emission amount per area) in the functional layer 7 is substantially proportional to the current density, and this current density is inversely related to the film thickness of the functional layer 7.
Further, in the peripheral portion 72, the thickness of the portion in contact with the end portion 53 of the anode plate 5 is always more than about twice the thickness d 1 in the central portion 71, and the functional layer at the edge portion 55 of the anode plate 5. The film thickness d3 of 7 is also about twice or more the film thickness d1.

Therefore, when a voltage is applied between the anode plate 5 and the cathode layer 8 when the display panel 100 is driven, in the area where the peripheral portion 72 is in contact with the inclined portion 52, the outer side (the arrow) The light emission intensity decreases in the direction opposite to Y), and all the regions outside the point P1 are non-light emission regions whose light emission intensity is ½ or less of the light emission intensity at the central portion 71.
On the other hand, also in the peripheral portion 73, the film thickness d4 of the functional layer 7 in contact with the inclined portion 54 of the anode plate 5 gradually increases from the central portion 71 side to the outside (arrow Y direction).

The film thickness of the functional layer 7 on the edge portion 56 of the anode plate 5 is at least twice the film thickness d1 of the functional layer 7 in the central portion 71.
In FIG. 4, the point P 2 is a point where the film thickness d 4 of the functional layer 7 is twice the film thickness d 1 of the functional layer 7 in the central portion 71, that is, the light emission intensity is 1 of the light emission intensity in the central portion 71. This corresponds to a point (a boundary between the light-emitting region and the non-light-emitting region) that is / 2, that is, a point at which the film thickness is approximately twice the average film thickness d1.

Also in the peripheral portion 73, in the region in contact with the inclined portion 54, the emission intensity decreases from the central portion 71 side toward the outside (in the direction of the arrow Y), and the emission intensity is always in the central portion 71 outside the point P2. It becomes a non-light-emitting area | region below 1/2 of emitted light intensity.
As is apparent from the above description, in the peripheral portion 72, the average film thickness d1 of the functional layer 7 in the central portion 71 and the film thickness d2 of the functional layer 7 at the boundary (point P1) from the light emitting region to the non-light emitting region. The film thickness d3 of the functional layer 7 at the edge 55 is in a relationship of d1 <d2 <d3. Further, the average film thickness d1 of the functional layer 7 in the central portion 71, the film thickness d4 of the functional layer 7 at the boundary (point P2) from the light emitting region to the non-light emitting region, and the functional layer 7 in the outer edge 56. The film thickness d5 has a relationship of d1 <d4 <d5.

[Effects of display panel 100]
First, a mechanism for generating edge light emission in an organic EL element according to a conventional example will be described with reference to FIG. This figure shows a cross section of the display panel cut in a direction (vertical direction) in which pixel electrodes are arranged.
In the example shown in FIG. 9, an anode plate 105 that is a pixel electrode is formed on the interlayer insulating film 103, and the functional layer 107 (hole transport layer 107 a, light emitting layer 107 b, etc.) and cathode layer 108 are covered so as to cover the anode plate 105. Are sequentially stacked. In this case, the thickness of the functional layer 107 may be locally reduced on the edge portion 105a of the anode plate 105 (portion indicated by A in the drawing). As a result, when a voltage is applied between the anode plate 105 and the cathode layer 108, current may concentrate and flow in a region where the thickness of the functional layer 107 is reduced, which may cause edge light emission.

Such edge light emission can suppress concentration of current by covering a portion where the anode plates 105 are adjacent to each other with a pixel regulation layer made of an insulating material. However, in order to form such a pixel restricting layer 110, a film forming process for forming the material of the pixel restricting layer 110 and a patterning process for patterning the formed film are required, which increases the number of manufacturing processes.
On the other hand, in the display panel 100 according to the embodiment, line-shaped partition walls 6 are formed along both sides of the plurality of anode plates 5 arranged in the vertical direction as described above, and each organic panel In the EL element 20, the edge that extends in the vertical direction along the partition 6 among the edges of the anode plate 5, that is, the edge that extends in the Y direction in FIG. Therefore, edge emission at the edge is suppressed by the partition wall 6.

Of the edge portions of each anode plate 5, the edge portions extending in the lateral direction along the partition walls 6, that is, the edge portions extending in the X direction in FIG. Although not possible, since the film thickness of the functional layer 7 is set as described above, edge emission at the edge is suppressed.
That is, in the functional layer 7, in a region 70 sandwiched between the anode plate 5 and the cathode layer 8, the central portion 71 with respect to the vertical direction (X direction) is a light emitting region, and the peripheral portions 72 and 73 are from the central portion side. The film thickness gradually increases toward the outside, and shifts from the light emitting region to the non-light emitting region. The entire outer region including the edge portion is thicker than the boundary between the light emitting region and the non-light emitting region, and is a non-light emitting region.

Therefore, even if the portion where the edge portions 55 and 56 of the anode plate 5 are present is not covered with the pixel regulation layer or the like, edge light emission does not occur in the peripheral portions 72 and 73 of the functional layer 7.
As described above, in the display panel 100, edge emission is suppressed over the entire periphery of the edge of the anode plate 5 in each organic EL element 20, and there is no need to provide a step of forming a pixel regulating layer.

Further, in the display panel 100, the peripheral portions 72 and 73 of the functional layer 7 are formed on the inclined surfaces 15a and 15c and the bottom surface of the contact hole 15 so that the light emitting region extends over the adjacent contact holes 15. Therefore, a large area ratio of the light emitting region can be secured.
Further, in the display panel 100, in each organic EL element 20, in the peripheral portions 72 and 73 of the functional layer 7, the thickness of the functional layer 7 monotonously increases from the central portion 71 side toward the outside. The emission intensity gradually decreases outward from the central portion 71 side, and smoothly shifts from the light emitting region to the non-light emitting region.

[Configuration Example of Display Device Using Display Panel 100]
FIG. 7 is a diagram illustrating a configuration of a display device 200 using the display panel 100.
The display device 200 includes a display panel 100 and a drive control unit 120 connected thereto. The drive control unit 120 includes four drive circuits 121 to 124 and a control circuit 125.

FIG. 8 is an external shape showing an example of a television system using the display device 200.
When the display panel 100 is driven, a voltage is applied between the anode plate 5 and the cathode layer 8 in each of the organic EL elements 20a, 20b, and 20c, and holes supplied from the anode plate 5 side in the functional layer 7 are displayed. And electrons supplied from the cathode layer 8 side combine to emit light, whereby an image is displayed on the entire display panel 100.

[Method for Manufacturing Display Panel 100]
An example of a method for manufacturing the display panel 100 will be described below with reference to FIG.
First, the TFT substrate 1 shown in FIG. 5A is manufactured, and the interlayer insulating film 3 is patterned as follows.

Interlayer insulation film 3 formation process:
An interlayer insulating film 3 is formed with a thickness of about 4 μm on the TFT substrate 1 so as to cover the TFT layer of the TFT substrate 1 (FIG. 5B). At this time, a contact hole 15 is formed on the SD electrode 2 in the interlayer insulating film 3. The interlayer insulating film 3 having such a contact hole 15 can be formed by spin-coating a known photosensitive organic material (for example, siloxane copolymer type photosensitive polyimide) and patterning it by a photolithography method using a pattern mask. .

Here, since the opening shape of the contact hole 15 is formed based on the opening shape formed in the pattern mask, the opening shape of the contact hole 15 can be adjusted by adjusting the opening shape of the pattern mask. it can.
The inclination angles α1 and α2 of the inclined surfaces 15a and 15c of the contact hole 15 are adjusted by, for example, selecting a photosensitive organic material to be used, adjusting an exposure amount, selecting a pattern mask to be used, and setting a baking temperature. Can do.

In addition, the contact hole 15 can also be formed by forming a uniform interlayer insulating film and then removing the portion where the contact hole is to be formed by etching.
That is, a desired resist pattern is formed by applying a photoresist on a uniform interlayer insulating film, exposing using a photomask, and developing. After that, after patterning the interlayer insulating film by wet etching or dry etching, the contact hole 15 can be formed by removing the resist using a stripping solution.

As an example of the size of the contact hole 15, each of the inclined surface 15a and the inclined surface 15c in the contact hole 15 has a height of about 4 μm and a length in the vertical direction (Y direction) of about 4 μm. The bottom surface 15b of the contact hole 15 has a length in the vertical direction (Y direction) of about 8 μm.
After forming the interlayer insulating film 3 on the TFT substrate 1 as described above, each layer constituting the organic EL element is formed as described below.

Anode plate 5, hole injection layer forming step:
On the interlayer insulating film 3, the anode plate 5 made of a metal electrode is formed by forming a metal material of the anode plate 5 into a predetermined thickness of, for example, 50 nm to 400 nm by sputtering and patterning by wet etching. .
On this metal electrode, an oxide of molybdenum or tungsten is formed by a typical manufacturing method (for example, sputtering), and patterned by photolithography and wet etching to form a hole injection layer.

At this time, since the metal electrode layer is also formed in the contact hole 15, the inclined portion 52, the end portion 53, and the inclined portion 54 of the anode plate 5 are formed in the contact hole 15, and the end portion 53 is the SD electrode 2. To be electrically connected (FIG. 5C).
Partition 6 formation process:
As the partition wall material, for example, a photosensitive resist material or a resist material containing fluorine or acrylic material is applied on the interlayer insulating film 3 and patterned by a photolithography method to form the partition wall 6. The height of the partition wall 6 is about 1 μm.

In this partition formation step, plasma treatment may be performed to adjust the contact angle of the partition 6 with respect to the ink to be applied next or to impart liquid repellency to the surface.
Functional layer 7 formation process:
On the hole injection layer, the hole transport layer 7a is formed as follows, and then the light emitting layer 7b is formed to form the functional layer 7.

The hole transport layer 7a is formed by a wet method (FIG. 5D).
That is, an organic material that is a material of the hole transport layer 7a and a solvent are mixed at a predetermined ratio to prepare an ink, and the ink is applied between adjacent partition walls 6 by an inkjet method.
The applied ink entirely covers the plurality of anode plates 5 arranged in the vertical direction (Y direction) and enters the contact hole 15, and in the contact hole 15, the inclined portion 52, In the region in contact with 54, the thickness of the ink layer gradually increases from the center side to the outside.

The hole transport layer 7a is formed by drying the ink layer thus formed (FIG. 5E). The film thickness is uniformly thin at the central portion (on the flat surface of the interlayer insulating film 3), but increases from the central portion side toward the outside in the region in contact with the inclined portion 52 at the peripheral portion. Even in the region in contact with the inclined portion 54 in the peripheral portion, the film thickness smoothly increases from the central portion side to the outside.
Further, since the thickness of the hole transport layer 7a after drying is substantially proportional to the thickness of the ink layer applied to each region in the ink application step of FIG. 5D, the thickness of the ink layer in the contact hole 15 is If the thickness of the hole transport layer 7a after drying is set on the interlayer insulating film 3 in the contact hole 15, if the thickness is set to be an appropriate thickness that is twice or more the thickness of the ink layer on the interlayer insulating film 3. On the other hand, it becomes an appropriate thickness approximately twice or more.

For example, a film thickness of about 50 nm to 100 nm can be obtained after drying at a portion where the ink film thickness is 5 to 6 μm using an ink having a concentration of 0.5 to 1%.
Next, the light emitting layer 7b is formed on the hole transport layer 7a by a wet method. This step is the same as the organic layer forming step, and is formed by applying an ink in which a material for forming a light emitting layer is dissolved between adjacent partition walls 6 and drying. However, the light emitting layer material used is different for each emission color.

The light emitting layer 7b is formed by drying the ink layer thus formed. The film thickness of the light emitting layer 7b is also uniform in the central part of each organic EL element 20, but the film thickness gradually increases from the central part side to the outside in the region in contact with the inclined part 52 in the peripheral part. Even in the region in contact with the inclined portion 54 in the peripheral portion, the film thickness gradually increases from the central portion side to the outside.
Since the functional layer 7 is formed by laminating the hole transport layer 7a and the light emitting layer 7b, the thickness thereof is uniform in the central portion 71 of each organic EL element 20, but the inclined portion of the peripheral portion 72 is the same. In the region in contact with 52, the film thickness gradually increases from the central portion 71 side to the outside, and becomes an appropriate thickness that is twice or more the film thickness in the central portion 71. Even in the region of the peripheral portion 73 in contact with the inclined portion 54, the film thickness gradually increases from the central portion 71 side to the outside, and becomes an appropriate thickness that is twice or more the film thickness in the central portion 71.

If the functional layer 7 is formed by the wet method as described above, the film thickness of the functional layer 7 in the peripheral portion can be easily set in each organic EL element 20.
Further, the rate of change of the thickness of the functional layer 7 on the inclined surfaces 15a and 15c is adjusted by adjusting the taper angles α1 and α2 when forming the inclined surfaces 15a and 15c of the contact hole 15 in the interlayer insulating film 3 formation step. Can also be adjusted.

In addition, as a method of filling the ink for forming the hole transport layer 7a and the light emitting layer 7b between the partition walls 6, in addition to the ink jet method, a dispenser method, a nozzle coating method, a spin coating method, intaglio printing, letterpress printing, etc. It may be used.
Step of forming cathode layer 8 and sealing layer 9:
Next, a material such as ITO or IZO is formed on the surface of the light emitting layer 7b by a vacuum deposition method. Thereby, the cathode layer 8 is formed. Further, a sealing layer 9 is formed on the surface of the cathode layer 8 by depositing a material such as SiN (silicon nitride) or SiON (silicon oxynitride) by a CVD method or a sputtering method.

The display panel 100 is manufactured through the above steps.
[Variations etc.]
(1) FIG. 6 is a cross-sectional view showing a modification of the display panel 100.
This display panel is the same as the display panel 100, but as shown in FIG. 6, a partition wall 6 a is formed on the bottom surface 15 b of the contact hole 15 so as to cover the end portion 53 of the anode plate 5. The partition wall 6 a is formed by applying the same material as the partition wall 6 to the contact hole 15 in the step of forming the partition wall 6.

In the display panel according to this modification, the functional layer 7 is not formed on the end portion 53 of the anode plate 5 in each organic EL element 20, but on the inclined portion 52 and the inclined portion 54 of the anode plate 5. The functional layer 7 is formed, and the thickness of the functional layer 7 in the portion increases from the center side to the edge portion in contact with the partition wall 6a, and the vicinity of the edge portion of the functional layer 7 becomes a non-light emitting region. Yes.
Therefore, in each organic EL element 20, edge light emission does not occur at the end of the region sandwiched between the anode plate 5 and the cathode layer 8 in the functional layer 7.

Further, by providing the partition wall 6a in the contact hole 15, the following effects are also obtained.
When the contact hole 15 has a deep depth (for example, about 4 μm), when the ink for forming the functional layer is applied to cover the contact hole 15, the surface of the ink layer applied on the contact hole 15 is recessed, and the ink The leveling property may deteriorate. In particular, when the functional layer 7 is formed using an ink having a high viscosity, the leveling property tends to deteriorate.

On the other hand, if the partition wall 6a is formed on the bottom surface of the contact hole 15, even if the amount of ink applied in the contact hole 15 is small, the contact hole 15 is filled with ink, so that the leveling is good. .
In addition, since the formation of the partition wall 6a can be performed simultaneously in the process of forming the partition wall 6, the number of processes does not increase.

(2) In the display panel 100, one pixel is composed of three colors of sub-pixels (three organic EL elements), but the present invention can be similarly implemented even when one pixel is composed of one organic EL element. It is.
(3) In the display panel 100, the case where the hole transport layer 7a and the light emitting layer 7b are formed as the functional layer 7 on the anode plate 5 has been shown. When the layer 7 is formed of a light emitting layer and an electron transport layer, the functional layer 7 is formed of a hole transport layer, a light emitting layer, and an electron transport layer, or a hole injection layer, a hole injection / transport layer, and the like are further formed. The same effect can be obtained by setting the shape of the thickness of the functional layer 7 in each organic EL element 20 in the same manner.

(4) In the display panel 100, the functional layer 7 is formed by the wet method. However, the functional layer 7 is not necessarily formed by the wet method, and may be formed by changing the film thickness of the functional layer 7 for each region using a method other than the wet method. That's fine.
(5) In the display panel 100, the inclined portion 52 and the inclined portion 54 of the anode plate 5 in each organic EL element 20 are formed on the inclined surface in the contact hole 15, but the inclined portion 52 and the inclined portion 54 are Even if it is not a contact hole, it can be similarly implemented by forming an inclined surface on the surface of the interlayer insulating film 3 and forming the inclined portion 52 and the inclined portion 54 of the anode plate 5 thereon.

(6) In the display panel 100, the first electrode directly above the interlayer insulating film 3 is the anode plate, and the second electrode opposed across the functional layer is the cathode layer, but the first electrode is the cathode and the second electrode. The same applies to an EL element having an inverted structure in which the electrode is an anode.
(7) In the above embodiment, an organic EL panel in which a plurality of organic EL elements are arranged along a line-shaped partition on a substrate has been shown. In the entire peripheral part surrounding the central part of the region sandwiched between the first electrode and the second electrode in the functional layer, an inclined part is similarly formed in the first electrode, and the thickness of the functional layer is increased from the central part side to the outside. By setting so as to increase, edge light emission can be suppressed by forming a non-light emitting region at the edge in the entire peripheral part.

  Further, the present invention is not limited to the case where a plurality of EL elements are arranged on the substrate, but can be similarly applied to a display element in which one EL element is formed alone, and the same effect can be obtained.

  The light-emitting panel according to the present invention is suitable as a display for a mobile phone or a television.

DESCRIPTION OF SYMBOLS 1 TFT substrate 2 SD electrode 3 Interlayer insulating film 4 Substrate 5 Anode plate 6 Partition 7 Functional layer 7a Hole transport layer 7b Light emitting layer 8 Cathode layer 9 Sealing layer 15 Contact hole 15a, 15c Inclined surface 15b Bottom surface 20 Organic EL element 51 Center Part 52 Inclined part 53 End part 54 Inclined part 55, 56 Edge part 70 Region sandwiched between anode plate 5 and cathode layer 8 71 Central part 72, 73 Peripheral part 100 Display panel

Claims (6)

A substrate, an insulating layer provided on the substrate, a first electrode provided on the insulating layer, a functional layer provided on the first electrode, and the first layer via the functional layer. A second electrode provided opposite to the one electrode,
The region sandwiched between the first electrode and the second electrode in the functional layer is:
Having a central portion and a peripheral portion outside the central portion;
The central portion of the functional layer is formed flat with a film thickness that emits light when a voltage is applied between the first electrode and the second electrode,
In the functional layer, when D is a film thickness at which light emission intensity when voltage is applied between the first electrode and the second electrode is ½ of light emission intensity at the central portion,
In the periphery,
The thickness of the functional layer increases until it becomes D from the center side toward the outside,
Wherein in the outer side than portions where the film thickness of the functional layer is D, Ri film der always more D is the thickness of said functional layer and the first electrode up to the edge of the functional layer overlap region,
In the insulating layer, an inclined surface inclined with respect to the substrate is formed in a region where the peripheral portion exists,
The first electrode has an electrode inclined portion provided along the inclined surface.
Light emitting element. In the periphery,
The thickness of the functional layer monotonously increases from the center side toward the outside.
The light emitting device according to claim 1. The film thickness of the functional layer in the central portion is
Always smaller than D,
The light emitting device according to claim 1. A substrate, an insulating layer provided on the substrate, a plurality of first electrodes arranged in one direction along a surface of the insulating layer, and on both sides of the plurality of first electrodes arranged A pair of line bulkheads provided along;
A functional layer provided on the plurality of first electrodes between the pair of line partition walls, and a second electrode provided to face the plurality of first electrodes through the functional layer,
Each region sandwiched between the first electrode and the second electrode in the functional layer is:
A central portion in the one direction and a peripheral portion on both outer sides of the central portion;
The central portion of the functional layer is formed flat with a film thickness that emits light when a voltage is applied between the first electrode and the second electrode,
In the functional layer, when D is a film thickness at which light emission intensity when voltage is applied between the first electrode and the second electrode is ½ of light emission intensity at the central portion,
In the periphery,
The thickness of the functional layer increases until it becomes D from the center side toward the outside,
Outside than locations film thickness of D, the thickness of the functional layer up to the edge of the region where the first electrode and the functional layer overlap always Ri der than D,
In the insulating layer, an inclined surface inclined with respect to the substrate is formed in a region where the peripheral portion exists,
The first electrode has an electrode inclined portion provided along the inclined surface.
Luminescent panel. The insulating layer is formed with a contact hole that is a recess for connecting each first electrode and the TFT,
The contact hole has an inclined side wall surface tapered,
Each of the first electrodes is present on the side wall surface of the corresponding contact hole at each of both edges.
The light emitting panel according to claim 4 . In the contact hole,
The same material as that forming the line partition is embedded,
The light emitting panel according to claim 5 .

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