JP2003022035A - Organic el panel and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL panel provided with through-holes which make a good connection between elements. SOLUTION: The organic EL panel has an active matrix driving system. In the panel, a substrate, an organic layer which is made on the substrate and includes switching elements, an insulation film, a first electrode and a light emitting layer and a second electrode are successively formed. A through-hole is provided to connect the first electrode and the switching elements through the insulation film. The through-hole has a conic taper whose inner peripheral surface becomes smaller as it moves from the first electrode to the switching element. Light emission of the light emitting layer by the driving of the switching element is taken out from the second electrode side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL panel and a manufacturing method thereof, and more particularly to an active matrix driving type organic EL panel and a manufacturing method thereof.

[0002]

2. Description of the Related Art An organic EL panel constitutes a display by using an organic EL element (electroluminescence) in which an organic material layer including a fluorescent light emitting layer is sandwiched by electrodes as a pixel, and the organic EL element is driven at a low voltage and has a high voltage. It has features such as brightness and high-speed response. In particular, an active matrix drive type organic EL panel using a switching element in each pixel can suppress the instantaneous luminance to be lower than that of a duty drive panel and can improve the display quality.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
As disclosed in Japanese Patent No. 805, a conventional active matrix drive type organic EL panel usually has a structure in which light emission is taken out from the substrate side. However, the actual light emitting area with respect to the area of one pixel, that is, the so-called aperture ratio, is reduced by the portion made of a material that does not transmit light, such as the switching element on the substrate and the wiring portion thereof.

On the other hand, in the conventional active matrix drive type organic EL panel, as shown in FIG. 4, the electrode 104 of the organic material layer 105 including the light emitting layer, the switching element 2 and the like formed on the substrate 101 are usually , Through a through hole 107 penetrating the insulating film 103.
Since the above-mentioned through holes are usually formed with a depth of several microns, if the holes are not formed at the time of forming the through holes or if the formed through holes are insufficiently filled with the electrode material, the connection between the switching element and the electrode will be defective. There is a problem that is likely to occur.

The present invention has been made in view of these problems, and it is an object of the present invention to provide an organic EL panel having a through hole that enables good connection between elements.

[0006]

According to the present invention, a substrate, a switching element, an insulating film, a first electrode, an organic layer including a light emitting layer, and a second electrode are sequentially formed on the substrate, and the insulating film penetrates the insulating film. And has a through hole for connecting the first electrode and the switching element, and the inner peripheral surface of the through hole is the first
There is provided an organic EL panel of an active matrix drive system, which has a conical taper that becomes smaller from an electrode toward a switching element and takes out light emission of a light emitting layer by driving the switching element from a second electrode side.

That is, in a conventional through hole whose inner peripheral surface is formed parallel to the axis of the through hole, the opening does not reach the switching element, or the through hole is made of an electrode material when the electrode is formed. If the connection is not satisfied, the connection failure occurs. However, in the present invention, the through hole is formed with the conical taper whose inner peripheral surface becomes smaller from the first electrode toward the switching element.
It is possible to surely secure the perforation that opens in the switching element, and it becomes easy to surely fill the through hole with the electrode material when the first electrode is formed, so that good connection between the elements is possible.

According to another aspect of the present invention, a switching element, an insulating film, a first electrode, an organic material layer including a light emitting layer, and a second electrode are sequentially formed on a substrate, and the first electrode penetrates through the insulating film. When manufacturing an organic EL panel having a through hole for connecting a switching element with a switching element, a pilot hole having the same diameter is formed in an insulating film formed on a substrate in the axial direction, and then the pilot hole is heated to form an inner circumference. Provided is a method for manufacturing an organic EL panel in which a through hole having a conical taper whose surface decreases from the first electrode toward the switching element is formed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the organic EL panel of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. Embodiment 1 FIG. 1 is a front sectional view showing the structure of an organic EL panel according to Embodiment 1 of the present invention. In FIG. 1, organic E
The L panel 10 includes a substrate 1, a switching element 2, a flattening film 3 (insulating film), a first electrode 4, an organic material layer 5 including a light emitting layer, and a second electrode 6 which are sequentially formed on the substrate 1. It has a through hole 7 penetrating the oxide film 3 and connecting the first electrode 4 and the switching element 2. Switching element 2
A capacitor 8 for holding data is provided on the substrate 1 near the
Are formed. The switching element 2 and the capacitor 8 are connected to a power supply circuit section (not shown).

Active matrix drive type organic EL
The panel 10 has a structure in which the light emission of the light emitting layer is driven based on a signal from the switching element 2 and this light emission is extracted from the second electrode 6 on the side opposite to the substrate 1. Organic EL
The panel 10 is characterized in that the through hole 7 has a conical taper whose inner peripheral surface becomes smaller from the first electrode 4 toward the switching element 2.

The manufacturing procedure of the organic EL panel 10 is as follows.
The configuration of each part of the panel 10 will be described. Substrate 1 is
There is no particular limitation as long as it is an insulating material, and a light-transmitting or non-light-transmitting substrate can be used, and examples thereof include a glass substrate, a ceramic substrate, and a enamel substrate. Glass substrates that are mass-produced for enamel substrates and liquid crystal displays are preferable because they reduce costs. The ceramic substrate is preferable because it has a high heat resistance temperature, and when a polysilicon TFT is used for a switching element, the heat treatment temperature can be raised above the softening point of glass and the characteristics of the TFT element can be improved.

In manufacturing the organic EL panel 10, first, the switching element 2 and the capacitor 8 are formed on the glass substrate 1 by a known method. The switching element 2 is a MIM element (Metal Insulator Metal) used in an active matrix drive type organic EL panel.
Alternatively, a TFT element (Thin Film Transistor) can be used. TFT elements are widely used in liquid crystal displays, etc.
Since the process is well established, it is easy to handle in design and manufacturing. Further, since the MIM element has a simple structure as a switching element, the number of masks used is small, and the number of processes can be reduced, the manufacturing cost of the organic EL panel can be reduced.

Next, a flattening film 3 is formed on the substrate 1 so as to cover the switching elements 2 and the capacitors 8. The flattening film 3 is a base layer for eliminating unevenness on the surface due to the formation of the switching element 2 and the capacitor 8 and performing a flat lamination thereon, and is a film of several microns by a coating method such as spin coating. An acrylic photosensitive resin or the like having a property capable of forming a thickness is preferable in that inexpensive equipment can be used and the process can be simplified. The above resins generally have hygroscopicity, and water may adversely affect the switching element 2. Therefore, it is preferable to form an inorganic insulating film such as SiO or SiN before forming the flattening film 3.

Next, the above resin, which is a material for the flattening film 3, is applied onto the substrate 1 by a spin coating method so as to have a thickness of 4 to 5 μm, and prebaked at 70 to 80 ° C. for 10 to 10.
Do it for 30 minutes.

Next, the through hole 7 is formed. According to the present invention, as shown in FIG. 2, the through hole 7 whose inner peripheral surface is inclined at an inclination angle θ of 30 degrees or more with respect to the axis Z of the through hole is formed. Therefore, the lower hole 7a of the through hole 7 penetrating the flattening film 3 is provided. As shown in FIG. 2, the lower hole 7a is formed as a hole having the same diameter in the axial direction, that is, the inner peripheral surface is parallel to the axis Z of the through hole 7, but the desired through hole 7a is formed. The diameter D is determined according to the inclination angle θ of the inner peripheral surface and the contact resistance.

The formation of the pilot hole 7a is performed after the prebaking as described above.
The through-hole 7 is formed by exposing the resin laminated on the substrate 1 to ultraviolet rays and developing it using a photomask provided with an opening at a portion where the through-hole 7 needs to be formed. Then, post-baking is performed for 30 to 60 minutes at a temperature (for example, 220 to 250 ° C.) exceeding the softening point of the resin in order to incline the inner peripheral surface of the prepared hole 7a at a desired inclination angle θ. The conditions of this post-baking differ depending on the type of resin used and the required film thickness, but when reducing the tilt angle, a low temperature is used for a short time (eg 220 ° C., 30 ° C.).
When the inclination angle is increased, the temperature is increased at a high temperature for a long time (for example, 250 ° C., 60 minutes).

As a result, a through hole 7 is formed which penetrates the flattening film 3 and the inner peripheral surface of which has an inclination angle θ. The larger the inclination angle θ is, the better, preferably 30 degrees or more, and more preferably 45 degrees or more. If the inclination angle θ is 10 degrees or less, poor connection between the switching element and the first electrode is likely to occur.

Next, a layer made of an electrode material is formed on the entire surface of the flattening film 3 having the through holes 7, and the first electrode 4 is formed on a predetermined portion of the flattening film 3 by photolithography.
To form. As the electrode material forming the first electrode 4,
It is made of a material that reflects light. That is, since the light emitting layer has an isotropic property of emitting equal amounts of light both upward and downward, the first electrode 14 is a transparent electrode in the upper part of the drawing, that is, when light emission is taken out from the second electrode 6 side. If so, the light emitted from the light emitting layer to the lower side cannot be extracted, and the light emitting efficiency is reduced. In the present invention, by using a material that reflects light as the electrode material formed on the substrate, the light emitted downward from the light emitting layer can be reflected by the first electrode 14 and taken out from above, thus reducing the luminous efficiency. Can be prevented.

As such a light reflecting material, a metal material usually used for metal electrodes can be used, and a material having a reflectance of 50% or more is preferable. In particular, Al or A
A metal containing 1 as a main component is preferable because it generally has a reflectance of 80% or more. As the metal material, Al: L
i, Mg: Ag, Al: In, Al: Ca, Al: B
a, Al: Cs, Ca, Ba, Cs, Li, Mg, In
Etc.

On the other hand, since the first electrode 4 also has a role of injecting electrons into the organic layer 5, it is preferable that the work function is small, and 4.5 eV or less is desirable. Work function is 4.
When an electrode material of 5 eV or more is used, the barrier potential at the interface between the electrode and the organic layer increases, so that the driving voltage increases and the light emission efficiency decreases.

Examples of metals having a low work function include Li and M
Examples include g, Ca, Ba, Cs, In and the like. In general, a metal having a low work function is often unstable in air, so an organic EL panel having a high luminous efficiency can be obtained even if an alloy of these metals and a stable metal such as Al or Ag is used. . In order to increase the efficiency of electron injection from the first electrode 14 to the organic material layer 5, a layer of an alkali metal or alkaline earth metal halide is sandwiched between the metal electrode and the organic material layer 5,
It is preferable that the electrode has a two-layer structure including the halide layer and a metal electrode. In this case, even if the work function of the metal electrode is not low, Al, Al: Si, Al: Ti
It is possible to use a metal having a high reflectance such as. As the above-mentioned metal electrode, Al, Al: Li, Mg: Ag, Al:
Si, Al: Ti, Al: Ca, Al: Ba, Al: C
s and Al: In. LiF, which is relatively stable in the air and easy to deposit, is suitable as a halide of an alkali metal or an alkaline earth metal.

In FIG. 1, the switching element 2
The connection portion between the first electrode 4 and the first electrode 4 is not at the center of the pixel plane formed by the light emitting layer, but at a position away from the center.

Next, an organic material layer 5 including a light emitting layer is formed on the first electrode 4. The organic material layer 5 can be formed by a known method such as a vapor deposition method, a spin coating method, a printing method, an inkjet method, a transfer method, or the like. The organic material layer 5 may be configured by stacking charge transport layers such as a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection layer in addition to the light emitting layer. As a material for forming the light emitting layer, it is possible to use a low molecular weight material or a high molecular weight material that has been used for an organic EL element, and for example, tris (8-hydroxynato) aluminum (Alq ₃ ), Examples include bis (2-methyl-8-hydroxynato) (p-phenylphenolato) aluminum (BAlq ₃ ), thiazole derivative, benzoxazole derivative, benzothiazole derivative, quinacridone derivative, triphenylamine derivative, and fluorescent metal complex. To be

A case where the organic material layer 5 is formed by using the thermal transfer film method (transfer method) will be described. In the thermal transfer film method, a thin film layer to be transferred, for example, an electrode or an organic material layer is formed by a vapor deposition method, a spin coating method, a sputtering method or the like on a donor substrate composed of a PET (polyethylene terephthalate) film or the like. By attaching the donor substrate to the substrate so that the thin film layer is in contact with the substrate and applying energy such as laser light or heat from the donor substrate side,
This is a method of transferring the thin film layer to the substrate side.

An example of forming the organic material layer 5 using the thermal transfer film method is shown below. First, P with a thickness of 0.1 mm
On the ET film, an epoxy resin mixed with carbon particles was formed to a thickness of 5 μm as a light-heat conversion layer, and poly α-methylstyrene was formed to a thickness of 1 μm as a release layer. The film thus formed was used as a thermal transfer film. Then, a diamine derivative (α-NPD) was vapor-deposited as a hole transport layer and Alq ₃ was vapor-deposited at a thickness of 500 Å as a light emitting layer on the thermal transfer film.
The vapor deposition was carried out by using an ordinary boat resistance heating method, the degree of vacuum was approximately 1 × 10 ⁻⁴ Pa, and the vapor deposition rate was approximately 2 to 3 Å / sec.

Next, the thermal transfer film on which the organic material layer consisting of the hole transport layer and the light emitting layer is deposited is brought into close contact with the first electrode 4 and irradiated with laser light from the thermal transfer film side, whereby the organic material on the thermal transfer film is irradiated. The layer was transferred onto the first electrode 4 to form the organic material layer 5. The laser used was a YAG laser having a wavelength of 1068 nm, and the energy was 0.1 to 10 J / cm ² .

After peeling off the thermal transfer film, In ₂ O ₃ doped with ZnO at 10% was formed as the second electrode 6 facing the thermal transfer film.
A transparent electrode made of (IDIXO) was formed to a thickness of 150 nm to produce an organic EL panel 10. When such a thermal transfer method is used, high-definition patterning is possible by narrowing the beam diameter of the laser beam. Therefore, a high-definition organic EL panel, which was not possible by conventional vapor deposition using a metal mask, is used. Can be manufactured. Made organic EL
In the panel 10, the first electrode 4 is formed in a concave shape inclined from the connection portion to the end of the pixel plane, and the connection portion between the switching element 2 and the first electrode 4 is formed in the pixel plane formed by the organic layer 5. It is located a little far from the center.

Embodiment 2 In Embodiment 1 described above, the hole transport layer and the light emitting layer were vapor-deposited on the thermal transfer film, and then these organic material layers 5 on the thermal transfer film were transferred onto the first electrode 4. In the second embodiment, the second electrode 6 made of IDIXO is first formed on the transfer film, and then the hole transport layer and the light emitting layer are formed as in the first embodiment. Then, the organic layer 5 and the second electrode 6 on the thermal transfer film were transferred onto the first electrode 4. Except for the above, the organic EL panel 10 was manufactured under the same conditions as in the first embodiment. in this way,
By transferring the organic material layer 5 and the second electrode 6 at the same time, the number of transfer films can be reduced and the process can be simplified, and the manufacturing cost of the organic EL panel can be reduced.

Third Embodiment In the first embodiment, the first electrode 4 is formed in a concave shape that is inclined from the connection portion between the switching element 2 and the first electrode 4 to the end portion of the pixel plane, and First
Although the connection portion of the electrode 4 is located away from the center of the pixel plane formed by the organic material layer 5, in the second embodiment, the switching is performed in the organic EL panel 20 as shown in FIG. The connection portion between the element 2 and the first electrode 14 is located near the center of the pixel plane formed by the organic layer 15. The configuration is the same as that of the first embodiment except for the setting of the position of the connecting portion. In the organic EL panel 20, the inclination of the inner peripheral surface of the through hole 17 becomes gentle (the inclination angle is about θ = 50 to 80 degrees although it varies depending on the pixel size), and the first electrode 14,
Each layer of the organic material layer 15 and the second electrode 16 is formed in a concave shape having a gentle slope according to the slope of the inner peripheral surface of the through hole 17. By disposing the connecting portion between the switching element 2 and the first electrode 14 in the vicinity of the center of the pixel plane as described above, the inclination of the inner peripheral surface of the through hole 17 can be made most gentle. Therefore, the electrode material for forming the first electrode 14 is reliably filled, so that the connection failure can be minimized.

In the first to third embodiments described above, switching is performed with the first electrodes 4 and 14 through the through hole 7 having a conical taper whose inner peripheral surface decreases from the first electrodes 4 and 14 toward the switching element 2. The element 2 is connected. In such a configuration, the first electrodes 4 and 14 formed along the through hole 7 can be firmly attached to the inner peripheral surface of the through hole 7, so that the through holes are not formed when the electrodes are formed as in the conventional case. The through hole 7 can be easily filled with the electrode material even if the inner peripheral surface is not treated to increase the affinity with the electrode material, and the switching element 2 and the first electrode 4 are reliably connected. be able to. Further, since the light emission is taken out from the surface opposite to the substrate 1, a non-translucent substrate can be used, so that the choice of materials for the substrate 1 is expanded and the aperture ratio can be increased to 70% or more. Become.

Although the flattening film 3 is formed by using a resin having photosensitivity in the above embodiment, when the flattening film 3 is formed by using a resin having no photosensitivity, for example, the substrate 1 is used. The planarization film 3 is formed on the entire surface of the resin by the resin, the lower hole 7a of the through hole 7 is formed by a method such as dry etching, and then heat treatment is performed at a temperature exceeding the softening point of the resin. Through hole 7 with an inclined peripheral surface
Can be produced in the same manner as described above.

[0032]

According to the present invention, since the through hole is formed so that the inner peripheral surface has a conical taper that becomes smaller from the first electrode toward the switching element, it is possible to surely secure the perforation opening to the switching element. At the same time, it becomes easy to surely fill the through hole with the electrode material when the first electrode is formed, and good connection between the elements is possible. Further, since the light emission is extracted from the surface opposite to the substrate, a non-translucent substrate can be used, so that the choice of materials for the substrate is expanded and the aperture ratio is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a configuration of an organic EL panel according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view showing a through hole of the through hole formed when the through hole of FIG. 1 is manufactured.

FIG. 3 is a sectional view showing an example of the configuration of an organic EL panel according to Embodiment 3 of the present invention.

FIG. 4 is a cross-sectional view showing an example of the configuration of a conventional organic EL panel having through holes formed therein.

[Explanation of symbols]

1 substrate 2 switching elements 3 Flattening film (insulating film) 4 First electrode 5 Organic matter layer 6 Second electrode 7 through holes 7a pilot hole 10 Organic EL panel 20 Organic EL panel

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 33/06 H05B 33/06 33/10 33/10 33/14 33/14 AF term (reference) 3K007 AB02 AB11 AB15 AB18 BA06 BB07 CA01 CA02 CB01 DA01 DB03 EB00 FA01 5C094 AA05 AA10 AA32 AA43 BA03 BA04 BA27 CA19 DA09 DA13 DB01 DB04 EA04 EA05 EA06 EB02 EB10 FA04 HA12 A17 H12A12 HA17 A12 A17 H12A12 A12 A17 A12 A17 H12A12 A17 H12A12 A17 A12 A17 H12A15 A12 A12 A17 A12 A15 A12 H12A12 KK05

Claims (14)

[Claims] 1. A substrate, a switching element, an insulating film, a first electrode, an organic layer including a light emitting layer, and a second electrode are sequentially formed on the substrate, and the first electrode and the switching element are connected through the insulating film. The through hole has a conical taper whose inner peripheral surface becomes smaller from the first electrode toward the switching element, and the active of extracting light emitted from the light emitting layer by driving the switching element from the second electrode side. Matrix drive type organic EL panel. 2. The organic EL panel according to claim 1, wherein the insulating film is a flattening film made of a photosensitive resin. 3. The organic EL panel according to claim 1, wherein the inner peripheral surface of the through hole is inclined by 30 to 80 degrees with respect to the axis of the through hole. 4. The connection portion between the switching element and the first electrode is substantially at the center of the pixel plane formed by the light emitting layer, and the first electrode is formed in a concave shape inclined from the connection portion to the end portion of the pixel plane. The organic EL panel according to claim 1, wherein the organic EL panel is formed of: 5. The organic EL panel according to claim 1, wherein the first electrode has a light reflectance of 50% or more. 6. The organic EL panel according to claim 1, wherein the first electrode is made of a material having a work function of 4.5 eV or less. 7. The first electrode comprises Al: Li, Mg: Ag, A
7. An alloy comprising l: In, Al: Ca, Al: Ba, and Al: Cs, and a material selected from Ca, Ba, Cs, Li, Mg, and In. The organic EL panel described in 1. 8. The organic EL panel according to claim 1, wherein the first electrode has a two-layer structure of a halide of an alkali metal or an alkaline earth metal and a metal electrode. 9. A metal electrode comprising Al, Al: Li, Mg: A
g, Al: Si, Al: Ti, Al: Ca, Al: B
The organic EL panel according to claim 8, which is a material selected from a, Al: Cs, and Al: In. 10. The alkali metal halide is LiF.
The organic EL panel according to claim 8, which is 11. The organic EL panel according to claim 1, wherein the substrate is made of glass, ceramic or enamel. 12. The organic EL panel according to claim 1, wherein the switching element is an MIM element or a TFT element. 13. A switching element, an insulating film, and
Formed on a substrate when manufacturing an organic EL panel having a first electrode, an organic layer including a light emitting layer, and a second electrode formed in order, and having a through hole penetrating an insulating film to connect the first electrode and a switching element. A through hole having the same diameter is formed in the formed insulating film in the axial direction, and then the through hole is heated to form a through hole having a conical taper whose inner peripheral surface decreases from the first electrode toward the switching element. Organic E
L panel manufacturing method. 14. A donor substrate on which a second electrode and / or an organic material layer is formed in advance is attached to the substrate so that the organic material layer or the second electrode is in contact, and heat is applied from the donor substrate side to form the organic material layer and / or the organic material layer. Alternatively, the method of manufacturing an organic EL panel according to claim 13, wherein the second electrode is transferred to the substrate side.