JP2002008870A - Display device - Google Patents

Abstract

(57) [Problem] To provide a display device which can secure a degree of freedom in design and has excellent viewing angle characteristics. SOLUTION: A first electrode layer 4 provided on a substrate 1;
The light-emitting device includes a light-emitting layer provided on the first electrode layer and a second electrode layer provided on the light-emitting layer, and emits light emitted from the light-emitting layer from the second electrode layer. In the display device, the surface of the first electrode layer 4 on the light emitting layer 5 side is formed of a plurality of uneven patterns each having a gentle slope. The first electrode layer 4 is provided on a plurality of convex patterns 2b having a gentle slope formed on the front surface side of the substrate 1 with an underlying layer 3 covering the convex patterns 2b interposed therebetween. The surface is constituted by an uneven pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device,
In particular, the present invention relates to a display device in which a self-luminous element is provided on a substrate.

[0002]

2. Description of the Related Art Electroluminescence (e) of organic materials
An organic EL device using electroluminescence (hereinafter referred to as EL) is provided with an organic layer in which an organic hole transport layer and an organic light emitting layer are laminated between an anode and a cathode, and has high luminance by low voltage DC driving. It is attracting attention as a light emitting element capable of emitting light.

FIG. 7 shows an example of a display device using such an organic EL element. The display device shown in this cross-sectional view
A first electrode layer 102 provided on a substrate 101, an organic layer 103 provided on the first electrode layer 102, and a second electrode layer 104 provided on the first electrode layer 102 are provided. For example, the display device is located on the opposite side of the substrate 101,
In the case of a top emission type in which emission light is emitted from the electrode layer 104 side, the first electrode layer 102 is provided as an anode using a material having a large work function and having light reflectivity such as chromium (Cr). In addition, the second electrode layer 104 is provided as a cathode using a material having a small work function and having light transmittance, such as silver: magnesium (Ag: Mg). The organic layer 103 is formed by laminating an organic hole transport layer, an organic light emitting layer, and an organic electron transport layer as needed from the first electrode layer 102 side.

[0004] The display device configured as described above has a structure in which a hole injected from the first electrode layer 102 and a second electrode layer 104 are formed.
And the electrons injected from the organic layer 103 are recombined in the organic light emitting layer of the organic layer 103 to emit light.
Further, the light is reflected by the first electrode layer 102 and the second electrode layer 104
Taken out from the side.

[0005]

However, in the display device having such a structure, the first electrode layer 102 and the organic layer 103 are not provided.
Not only at the interface with the second electrode layer 104 but also at the organic layer 10.
The reflection of the emitted light h also occurs at the interface 3. In particular, in the top emission type display device described above, the second electrode layer 104 is used.
Is used as a cathode, the second electrode layer 104 needs to be made of a material having a small work function, so silver: magnesium (Ag: Mg) or the like is used. This is a translucent reflective material. Reflects the emitted light h.

For this reason, the emitted light h is transmitted to the second electrode layer 10.
4 and the first electrode layer 102, there is a case where the light of the resonance wavelength is enhanced and extracted from the second electrode layer 104 side. At this time, since the resonated light has a spectrum with a high peak and a narrow width, when the light emitting surface is viewed from an oblique direction, the wavelength of the light h is largely shifted or the light emission intensity is reduced. For this reason, the viewing angle dependence of the display characteristics of the display device is increased.

In order to prevent this, it is necessary to design the distance between the second electrode layer 104 and the first electrode layer 102 so that the resonance of the emitted light h does not occur. This can be a factor in reducing the degree of freedom in designing.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a display device which can secure a degree of freedom in design and has excellent viewing angle characteristics.

[0009]

According to the present invention, there is provided a display apparatus comprising: a first device provided on a substrate;
An electrode layer; a light emitting layer provided on the first electrode layer; and a second electrode layer provided on the light emitting layer. The light emitted from the light emitting layer is emitted by the first electrode layer and the second electrode. In a display device which is taken out from one of the layers, the surface of the first electrode layer on the light emitting layer side is characterized by being constituted by a plurality of uneven patterns formed of gentle slopes.

In the display device having such a configuration, since the surface of the first electrode layer on the light emitting layer side is constituted by a plurality of uneven patterns having gentle slopes, the light emitted from the light emitting layer emits light. It diffuses when reflected at the interface between the layer and the first electrode layer. Therefore, even if the emitted light repeatedly reflects at the interface between the first electrode layer and the interface between the second electrode layers provided with the light emitting layer interposed therebetween, the emitted light may resonate. The emitted light without resonance is emitted from the first electrode layer or the second electrode layer side.

Further, another display device according to the present invention includes a first electrode layer provided on a substrate, a light emitting layer provided on the first electrode layer, and a first electrode layer provided on the light emitting layer. In a display device having two electrode layers and taking out light emitted from the light emitting layer from the second electrode layer side, a plurality of convex patterns made of a transparent material having a gentle slope are formed on the second electrode layer. It is characterized by having been provided.

In the display device having such a configuration, since the convex pattern made of a transparent material is provided on the second electrode layer, the emitted light extracted from the second electrode layer side is transmitted through the convex pattern. Is diffused and released. For this reason, the emitted light is emitted from the first light source provided between the light emitting layers.
Even in the case where the reflection is repeated at the interface between the electrode layer and the second electrode layer to cause resonance, the resonated light is diffused and emitted from the second electrode layer side.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the display device of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view of a display device according to a first embodiment of the present invention, showing an example of the present invention. 1 shows a configuration example when the present invention is applied. Hereinafter, the configuration of the display device shown in this figure will be described in detail in the order of the manufacturing process based on the sectional process diagram of FIG.

First, as shown in FIG. 2A, a substrate 1 made of glass or a silicon wafer is prepared.
A photosensitive resin film 2 is applied thereon. As the resin film 2, for example, an acrylic, imide, or novolac resin film is used, and is applied and formed on the substrate 1 by, for example, spin coating. The substrate 1 may be provided with a thin film transistor (not shown) as necessary.
sistor: TFT or thin film diod
e: TFD) or the like may be formed. In this case, these TFTs and TFDs are embedded with a flattening insulating film, and a resin film 2 is applied on the flattening insulating film. Shall decide.

Next, as shown in FIG. 2B, the resin film 2 is patterned by a lithography technique.
A plurality of convex patterns 2a are formed on the substrate 1 at high density.
Each convex pattern 2a is formed, for example, in a random polygonal column shape as shown in FIG.
An aggregate of a is provided. Further, when designing these convex patterns 2a, circles having a diameter of about 11 μm are arranged so as to be in contact with each other, and the boundaries of the circles in contact are continuously connected to a straight line and separated from each other. The interval between the convex patterns 2a is
It is set to the minimum resolution of lithography (for example, about 1 μ). The convex pattern 2a is not limited to a random polygonal column as shown in FIG.
It may be a prism or a cylinder having the same shape and arranged regularly.

Next, as shown in FIG. 2C, the convex pattern (2a) is softened and melted by a heat treatment at about 140 ° C., for example. As a result, a convex pattern 2b having a height of about 1.5 μm and having a gentle inclined surface on the center side due to surface tension is obtained. After that, a heat treatment at about 200 ° C. is further performed to harden the convex pattern 2b. The above steps are controlled so that the maximum inclination angle θmax of each convex pattern 2b is less than 12 °.

Here, when the rising angle of the side wall of the convex pattern 2b is steep, the space between the convex patterns 2b is buried with a material which can be selectively etched with respect to the convex pattern 2b. The inclination angle may be reduced so that the maximum inclination angle θmax is less than 12 °. In this case, first, after forming a burying material layer (not shown) on the substrate 1 in a state where the convex pattern 2b is buried, the burying material layer is selectively etched back so as to expose only the upper part of the convex pattern 2b. Convex pattern 2
The buried material layer is left only between b. Further, by providing the burying material layer between the convex patterns 2b in this manner, it is possible to cover the surface of the substrate 1 and eliminate a flat surface, thereby suppressing specular reflection.

Next, as shown in FIG. 2D, an underlayer 3 is formed so as to cover the convex pattern 2b on the substrate 1.
The underlayer 3 is made of, for example, a resin material, and has a sufficient film thickness (for example, such that the space between the convex patterns 2b is not completely buried and that the surface of the convex patterns 2b and the space between the convex patterns 2b are smoothly covered. 0.3 μm to 0.7 μm
Degree).

After the above, as shown in FIG.
The first electrode layer 4 is formed thereon. The first electrode layer 4 is used as an anode and is made of a material such as chromium (Cr), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), and tungsten (W). Among materials having a high function, a material having a high reflectance for the emitted light h in the display device is used. The first electrode layer 4 is formed by, for example, a sputtering method.
Thereafter, the first electrode layer 4 is patterned into a predetermined shape by performing etching using a resist pattern formed by a normal lithography technique as a mask. When a TFT or TFD is formed on the substrate 1, the first electrode layer 4 is formed on the base layer 3 or the convex pattern 2.
b. It is formed so as to be connected to these elements via a contact hole formed in the planarizing insulating film.

Next, a light emitting layer 5 is formed on the first electrode layer 4. At this time, for example, the light emitting layer 5 having an independent pattern shape is formed on each of the first electrode layers 4 by vacuum evaporation from a metal mask (not shown). The light emitting layer 5 includes an organic hole injection layer (not shown),
The organic EL layer is formed by sequentially laminating an organic light emitting layer also serving as an organic hole transport layer and an electron transport layer from the lower layer.

As an example of the light emitting layer 5 having such a configuration, MTDATA [4,4 ', 4 "-tris (3-methylphenylphenylamino) triphenylamine] having a thickness of 30 nm is used as an organic hole injection layer. To form α-NPD [bis (N-naphthyl) -N-phenylbenzidine] to a thickness of 20 nm as an organic hole transporting layer, and A as an organic light emitting layer.
50 n of lq3 (8-quinolinol aluminum complex)
m.

Next, a second electrode layer 6 used as a cathode is formed on the light emitting layer 5. The second electrode layer 6 has a small work function such as an alloy of magnesium and silver (Mg: Ag) and an alloy of aluminum and lithium (Al: Li), and has a small work function with respect to the emission light h in this display device. It is made of a conductive material having a light transmitting property. This second electrode layer 6
Is formed on the entire surface of the substrate 1 or on a necessary portion by, for example, an evaporation method.

Here, these conductive materials constituting the second electrode layer 6 are translucent reflective materials, and are formed with a small film thickness (for example, about 10 nm) in order to secure the luminance of the display device. Therefore, although not shown here, a transparent electrode film for protecting the second electrode layer 6 and reducing the resistance is formed on the second electrode layer 6. As the transparent electrode film, for example, an indium zinc oxide (In-Zn-O) -based transparent conductive material or the like showing good conductivity at room temperature is used, and the second electrode layer 6 is formed by DC sputtering. It is formed in the same shape.

As described above, a display device in which the first electrode layer (anode) 4, the light emitting layer (organic EL layer) 5, and the second electrode layer (cathode) 6 are sequentially laminated on the substrate 1 is obtained. In this display device, the surface on the light emitting layer 5 side of the first electrode layer 4 provided so as to cover the convex pattern 2b with the base layer 3 interposed therebetween is formed of a plurality of uneven patterns having gentle slopes. become.

In the display device having such a configuration, since the surface of the light emitting layer 5 in the first electrode layer 4 is constituted by a plurality of uneven patterns having gentle slopes, the light emitted from the light emitting layer 5 is generated. h is diffused when reflected on the surface of the first electrode layer 4 (the interface on the light emitting layer 5 side).
Therefore, the emitted light h is transmitted to the first electrode layer 4 having a high reflectance.
Even if reflection is repeated between and the second electrode layer 6 made of a translucent reflective material, this prevents the emitted light h from resonating. Moreover, the surface of the light emitting layer 5 formed on the first electrode layer 4 and the interface of the second electrode layer 6 on the light emitting layer 5 side are also formed with uneven surfaces reflecting the unevenness of the surface of the first electrode layer 4. . Therefore, the emitted light h generated in the light emitting layer 5 is:
When the light is reflected at the interface between the light emitting layer 5 and the second electrode layer 6, the light is diffused and the resonance of the emitted light h is prevented.

Therefore, regardless of the distance between the first electrode layer 4 made of a reflective material and the second electrode layer 6 made of a translucent reflective material, it is possible to prevent the resonance of the emitted light h and to improve the display characteristics. Viewing angle dependency can be suppressed. As a result, the degree of freedom in designing the light emitting layer 5 can be ensured,
In addition, a display device having good viewing angle characteristics can be obtained.

In addition, since the convex pattern 2b has a gentle slope, the light h reflected by the first electrode layer 4 is diffused and reflected toward the second electrode layer 6 to form a display device. Can be prevented from lowering. In particular, by setting the maximum inclination angle of the convex pattern 2b to θmax = 12 °, most of the light reflected on the first electrode layer 4 can be reflected toward the second electrode layer 6, and the luminance of the display device can be improved. Can be secured.

By forming the convex pattern 2b with the base layer 3, the inclination angle of the convex pattern 2b is reduced, and the base of the first electrode layer 4 is smoothed. It is possible to prevent local unevenness of the film thickness of the light emitting layer 5 formed on the substrate. Therefore, it is possible to prevent generation of a leakage current in the light emitting layer 5 and to perform stable display.

(Second Embodiment) FIG. 4 shows another configuration example when the present invention is applied to a top emission type display device. Hereinafter, the configuration of the display device shown in this figure will be described in detail in the order of the manufacturing process based on the sectional process diagram of FIG.

First, as shown in FIG. 5A, a substrate 1 similar to that of the first embodiment is prepared, and a mask pattern 8 is formed on the substrate 1 by lithography. In this mask pattern 8, a plurality of punched patterns 8a are formed at high density. These blank patterns 8a are, for example, reverse patterns of the convex patterns 2a described with reference to FIG. 2B in the first embodiment.

Next, as shown in FIG. 5 (2), a plurality of concave patterns 1 a are formed on the front surface side of the substrate 1 by etching from above the mask pattern 8. At this time, it is assumed that the concave pattern 1a has a gentle slope by performing wet etching. Here, control is performed so that the maximum inclination angle (θmax) of the convex pattern 2b is less than 12 °.

Next, as shown in FIG.
After removing the upper mask pattern (8), an underlayer 3 is formed on the substrate 1 so as to cover the concave pattern 1a.
The underlayer 3 is, for example, the same as the underlayer of the first embodiment.

After the above, as shown in FIG. 4, the first electrode layer 4 is formed on the underlayer 3 in the same manner as in the first embodiment.
The light emitting layer 5, the second electrode layer 6, and a transparent electrode layer (not shown) are formed as needed to complete the display device.

In the display device thus obtained, the surface of the first electrode layer 4 provided so as to cover the concave pattern 1a with the base layer 3 interposed therebetween is formed by a plurality of uneven patterns having gentle slopes. It will be composed.

Even in the display device having such a configuration, the surface of the first electrode layer 4 on the light emitting layer 5 side is formed into a gently sloped uneven surface. The same effect as that of the display device can be obtained, and the degree of freedom in designing the light emitting layer 5 can be ensured.
In addition, a display device having good viewing angle characteristics can be obtained.

Further, since the concave pattern 1a is constituted by a gentle slope, it is possible to secure the brightness of the display device, as in the first embodiment. Furthermore, by forming the concave pattern 1a with the base layer 3, the inclination angle of the concave pattern 1a is reduced, and the base of the first electrode layer 4 is smoothed, so that the concave pattern 1a is formed on the first electrode layer 4. Local unevenness of the film thickness of the light emitting layer 5 can be prevented. Therefore, stable display can be performed as in the first embodiment.

In the first and second embodiments described above, the embodiments in which the present invention is applied to the top emission type display device have been described. However, these embodiments
The present invention is also applicable to a transmissive display device that extracts emitted light from the substrate side. In this case, the substrate and the first electrode layer are configured using a transparent material, and the second electrode layer is configured using a reflective material. In addition, the order in which the organic layers forming the light emitting layer are stacked is appropriately determined depending on the materials forming the first electrode layer and the second electrode layer.

In such a transmission type display device,
Light emitted from the light emitting layer diffuses when slightly reflected at the interface between the first electrode layer made of a transparent conductive material and the light emitting layer. Also, in the second electrode layer laminated on the first electrode layer via the light emitting layer, the interface on the light emitting layer side is formed in an uneven surface. Therefore, the emitted light generated in the light emitting layer is diffused when reflected at the interface between the light emitting layer and the second electrode layer, and the resonance of the emitted light h is prevented. Therefore, the same effects as in the first embodiment and the second embodiment can be obtained.

In the first and second embodiments, the maximum inclination angle of the convex pattern 2b or the concave pattern 1a is set to less than 12 °. However, in the present invention, if the maximum inclination angle of the interface between the first electrode layer 4 and the second electrode layer 6 on the light emitting layer 5 side is less than 12 °, the brightness of the display device can be ensured. Therefore, as long as the maximum inclination angle of the surface of the first electrode layer 4 on the light emitting layer 5 side becomes θmax <12 °, the maximum inclination angle of the convex pattern 2b or the concave pattern 1a may exceed 12 °.

(Third Embodiment) FIG. 6 is a sectional view showing the structure of a display device according to a third embodiment. The display device shown in this figure has a plurality of transparent materials formed on the second electrode layer 6 (if a transparent electrode layer is provided) of the display device of the first embodiment described with reference to FIG. And the other configuration is the same as that of the display device of the first embodiment.

These convex patterns 9 are formed, for example, in the same manner as the convex patterns 2b described in the first embodiment, and the surfaces thereof are assumed to be constituted by gentle slopes.

In the display device having such a configuration, since the convex pattern 9 made of a transparent material is provided on the second electrode layer 6, the emitted light h extracted from the second electrode layer 6 side is
The light is diffused and emitted by transmitting through the convex pattern 9. For this reason, it is possible to further suppress the viewing angle dependence of the display characteristics as compared with the display device of the first embodiment.

Although the structure in which the convex pattern 9 is provided on the second electrode 6 of the display device of the first embodiment has been described here, the structure (transparent) on the second electrode layer 6 of the display device of the second embodiment has been described. In the case where the electrode layer is provided, the same effect can be obtained even with a configuration in which the convex pattern is provided on the transparent electrode layer).

Further, a configuration in which these convex patterns 9 are provided above the second electrode layer in the display device described in the related art may be used. In this case, even when the emitted light generated in the light emitting layer is repeatedly reflected at the interface between the first electrode layer and the second electrode layer provided with the light emitting layer interposed therebetween, the light is resonated. The emitted light is diffused by transmitting through the convex pattern 9. Therefore, it is possible to suppress the viewing angle dependency of the display characteristics as compared with the conventional display device.

[0046]

As described above, according to the display device of the present invention, the surface of the light emitting layer in the first electrode layer is constituted by a plurality of concave and convex patterns having gentle slopes, so that the light emitting layer is formed in the light emitting layer. The emitted light can be diffusely reflected at the interface between the light emitting layer and the first electrode layer.
Therefore, the resonance of the emitted light between the interface between the first electrode layer and the interface between the second electrode layers provided with the light emitting layer interposed therebetween can be prevented, and the viewing angle dependence of the display characteristics can be suppressed.
As a result, it is possible to secure a degree of freedom in designing the light emitting layer and to obtain a display device having good viewing angle characteristics.

According to the other display device of the present invention, since the convex pattern made of a transparent material is provided on the second electrode layer formed on the light emitting layer, the second electrode layer is taken out from the second electrode layer side. The emitted light can be diffused and emitted by passing through the convex pattern. Therefore, even if the emitted light generated in the light emitting layer is repeatedly reflected and resonated at the interface between the first electrode layer and the second electrode layer sandwiched between the light emitting layers, the light is diffused and diffused. The emission from the two electrode layer side can suppress the viewing angle dependence of the display characteristics.
As a result, it is possible to secure a degree of freedom in designing the light emitting layer and to obtain a display device having good viewing angle characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a display device according to a first embodiment.

FIG. 2 is a cross-sectional process diagram illustrating a procedure for manufacturing the display device of the first embodiment.

FIG. 3 is a plan view of a convex pattern in the display device of the first embodiment.

FIG. 4 is a cross-sectional configuration diagram of a display device according to a second embodiment.

FIG. 5 is a sectional process view showing a manufacturing procedure of the display device of the second embodiment.

FIG. 6 is a cross-sectional configuration diagram of a display device according to a third embodiment.

FIG. 7 is a cross-sectional configuration diagram of a conventional display device.

[Explanation of symbols]

1 ... substrate, 1a ... concave pattern, 2b ... convex pattern, 3 ...
Base layer, 4 first electrode layer, 5 light emitting layer, 6 second electrode layer, 9 convex pattern (made of transparent material)

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tatsuya Sasaoka 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 3K007 AB17 BA05 CA01 CA03 DA01 5C094 AA12 BA27 CA19 DA13 EA05 EB02 EB05 ED13 JA08 JA09

Claims (5)

[Claims] 1. A light emitting layer comprising: a first electrode layer provided on a substrate; a light emitting layer provided on the first electrode layer; and a second electrode layer provided on the light emitting layer. A display device that takes out the emitted light generated in step 1 from one of the first electrode layer and the second electrode layer, wherein the surface of the first electrode layer on the light emitting layer side has a plurality of irregularities having a gentle slope. A display device comprising a pattern. 2. The display device according to claim 1, wherein a plurality of concave patterns or convex patterns having a gentle inclined surface are formed on a front side of the substrate, and the first electrode layer is formed of the concave pattern or the convex pattern. A display device formed on the substrate so as to cover the convex pattern. 3. The display device according to claim 2, wherein an underlayer is provided between the substrate and the first electrode layer so as to cover the concave pattern or the convex pattern. apparatus. 4. The display device according to claim 1, wherein light emitted from the light emitting layer is extracted from the second electrode layer side. A transparent material having a gentle slope on the second electrode layer. A display device provided with a plurality of convex patterns comprising: 5. A light-emitting layer comprising: a first electrode layer provided on a substrate; a light-emitting layer provided on the first electrode layer; and a second electrode layer provided on the light-emitting layer. In the display device for extracting the emitted light generated in the above from the second electrode layer side, a plurality of convex patterns made of a transparent material having a gentle slope are provided on the second electrode layer. Display device.