Organic el display panel

The present invention relates to an organic EL display panel.

Organic devices such as organic semiconductor devices and organic EL devices usually have a functional layer containing an organic functional material arranged between an anode and a cathode. Depending on the function of the organic functional material, an organic device such as a semiconductor element (transistor), a light emitting element, or a liquid crystal element can be obtained. A semiconductor device has, for example, an organic semiconductor material that connects a source electrode and a drain electrode arranged on a substrate surface; an organic EL element includes, for example, an organic EL material laminated on an anode electrode arranged on a substrate surface. It has a layer, and a light emitting layer is further sandwiched between cathode electrodes.

In order to pattern the organic functional material on the electrode, a barrier (that is, a bank) surrounding the electrode surface may be formed and a composition containing the organic functional material may be printed in the area defined by the bank. The material of the bank may be resin.

When printing an ink containing an organic functional material in a region including an electrode surface defined by a bank, it is generally preferable that the region to be printed (including the electrode surface) has high wettability. It is preferable that the wettability of the upper surface of the bank is low. This is to prevent the ink from leaking out of the target area.

It is generally known that the fluorine component lowers the energy on the surface of the substance and lowers the wettability. Therefore, in order to form a bank having an upper surface having low wettability, a technique of plasma-treating the bank surface using a fluorocarbon-based gas is known (see Patent Document 1). However, when the surface of the bank is plasma-treated with a fluorocarbon-based gas, fluorine is usually not chemically bonded to the surface of the material such as the bank, but is simply adsorbed on the surface of the material by intermolecular force. Therefore, even if fluorine is adsorbed on the surface of the material by plasma treatment, migration of fluorine may occur due to a thermal process or the like. If fluorine migrates to, for example, the organic functional layer of an organic device, it deteriorates the device characteristics. In particular, if a fluorine atom having a high electron attracting property is mixed in the organic light emitting layer, there is a concern that the luminescent exciter is deactivated and the luminous efficiency is adversely affected.

As a means for solving the above problems, it has also been proposed to form a bank using a fluorinated photoresist (see Patent Document 2). Banks formed by photolithography processes such as coating, developing, cleaning, and firing fluorinated photoresists are characterized by low wettability without plasma treatment.<patcit num="1"><text>Japanese Patent Application Laid-Open No. 2005-52835</text></patcit><patcit num="2"><text>Special Table 2005-522000</text></patcit>

<p> As described above, a bank using a fluorinated photoresist has low wettability, and is therefore suitable as a bank for printing an organic material. However, in the bank using the fluorinated photoresist, the wettability of the wall surface of the bank may be low. Therefore, when an organic material is applied to form a functional layer in the region defined by the bank, the applied organic material is repelled by the wall surface of the bank and has a function of having a uniform film thickness in a desired region. In some cases it was not possible to form a layer.</p><p> According to the present invention, when a bank is formed using a fluorine photoresist, a functional layer having a uniform film thickness is formed in a region defined by the bank by controlling the wettability of the wall surface of the bank. The purpose.</p>

<p> That is, the first aspect of the present invention relates to the organic display panel shown below. [1] A substrate, an anode electrode formed on the substrate, an organic EL layer formed on the anode electrode, a first bank that defines a region of the organic EL layer in a line, and the first bank. An organic EL display panel having a second bank, which divides the area defined by the above into two or more areas. The height of the second bank from the substrate is lower than the height of the first bank from the substrate; the first bank and the second bank contain fluororesin, and each bank is in the thickness direction. An organic EL display panel that has a fluorine concentration gradient along it, and the fluorine concentration at the top of each bank is higher than the fluorine concentration at the bottom of each bank. [2] The organic EL display panel according to [1], wherein the fluorine concentration at the apex of the first bank is 5 to 10 atom%, and the fluorine concentration at the bottom surface of the first bank is 0 to 3 atom%.</p>

<p> Since the organic device of the present invention has a bank containing a fluororesin having a low wettability on the upper surface, the material of the functional layer applied to the region specified by the bank does not leak to other regions. Further, since the wettability of the wall surface of the bank is higher than that of the upper surface of the bank, a functional layer having a uniform thickness can be formed. In particular, when the bank containing the fluororesin of the organic device of the present invention is tapered forward, the wettability also has a gradient according to the thickness (the larger the thickness, the lower the wettability), so that a uniform functional layer is formed. It's easy to do.</p>

1. Organic EL element The organic EL device of the present invention includes a substrate, an anode electrode, a cathode electrode, a hole transport layer, an intermediate layer, an organic EL layer, and a bank.

The organic EL element of the present invention may have a thin film transistor (driving TFT) for driving the organic EL element, and even if the anode electrode of the organic EL element and the source or drain electrode of the driving TFT are connected. Good.

The material of the substrate of the organic EL element of the present invention differs depending on whether it is a bottom emission type or a top emission type. In the case of the bottom emission type, the substrate is required to be transparent, so any substrate such as glass or transparent resin may be used. On the other hand, in the case of the top emission type, the substrate does not have to be transparent, and the material is arbitrary as long as it is insulating.

An anode electrode is formed on the substrate. When the organic EL element is a bottom emission type, the anode electrode is required to be a transparent electrode, and may be formed by ITO or the like. When the organic EL display panel is a top emission type, the anode electrode is required to have light reflectivity. For example, if it is formed of an alloy containing silver, more specifically, a silver-palladium-copper alloy (also referred to as APC). Good.

A hole transport layer or an intermediate layer is arranged on the anode electrode. Both layers may be arranged on the anode electrode in the order of the hole transport layer and the intermediate layer. In addition, the hole transport layer may not be formed.

The hole transport layer is a layer made of a hole transport material. Examples of hole transporting materials include polystyrene sulfonic acid-doped poly (3,4-ethylenedioxythiophene) (referred to as PEDOT-PSS) and derivatives thereof (copolymers, etc.). The thickness of the hole transport layer is usually 10 nm or more and 100 nm or less, and can be about 30 nm. The material of the hole transport layer is WO_x(Tungsten oxide) and MoO_x(Molybdenum oxide), VO_xIt may be an oxide such as (vanadium oxide) or a combination thereof.

The intermediate layer has a role of blocking the transport of electrons to the hole transport layer and a role of efficiently transporting holes to the organic EL layer. The intermediate layer is, for example, a layer made of a polyaniline-based material. The thickness of the intermediate layer is usually 10 nm or more and 100 nm or less, preferably about 40 nm.

The hole transport layer and the intermediate layer are arranged in the region defined by the bank described later.

An organic EL layer is arranged on the intermediate layer. The organic material contained in the organic EL layer may be a low molecular weight system or a high molecular weight system. In the case of a low molecular weight organic EL material, a combination of a dopant material and a host material is included, examples of the dopant material include BCzVBi, coumarin, rubrene, DCJTB, etc., and examples of the host material include DPVBi, Includes Alq3 and more. Examples of high molecular weight organic EL materials include polyphenylene vinylene and its derivatives, polyacetylene and its derivatives, poly phenylene (PPP) and its derivatives, and poly para phenyleneethylene (PPV). And its derivatives, poly 3-hexyl thiophene (P3HT) and its derivatives, poly fluorene (PF) and its derivatives and the like. The organic material contained in the organic EL layer is preferably a polymer-based organic EL material. The organic EL layer may be formed in a region defined by a bank described later.

As described above, the organic EL device of the present invention has a bank that defines the region of the intermediate layer and the organic EL layer. The bank is characterized by containing a fluororesin. The fluororesin contained in the bank is not particularly limited as long as it has a fluorine atom in at least a part of the polymer repeating units. Examples of the fluororesin include a fluorinated polyolefin resin, a fluorinated polyimide resin, a fluorinated polyacrylic resin and the like. More specific examples of the fluororesin include, for example, the fluorine-containing polymer described in Japanese Patent Application Laid-Open No. 2002-543469; LUMIFLON (registered trademark, Asahi Glass), which is a copolymer of fluoroethylene and vinyl ether. included. The height of the bank from the substrate is 0.1 μm to 2 μm, particularly preferably 0.8 μm to 1.2 μm.

Further, the shape of the bank is preferably a forward taper shape. The forward taper shape means that the barrier surface of the bank is slanted and the area of the bottom surface of the bank is larger than the area of the top surface of the bank (see Fig. 1). When the shape of the bank is tapered, the taper angle is 20 to 80 °, particularly preferably 35 to 45 °.

The bank in the present invention is characterized in that the wettability of the upper surface of the bank is low. Here, the upper surface of the bank means a surface including the apex of the bank. Low wettability means that the contact angle of at least a part of the water on the upper surface of the bank is 80 ° or more, preferably 90 ° or more. Normally, the contact angle of water on the upper surface of the bank is 110 ° or less. Further, the bank in the present invention is characterized in that the bottom surface of the bank is highly wettable. High wettability means that the contact angle of at least a part of the water on the bottom surface of the bank is 70 ° or less, preferably 60 ° or less. As described above, the bank in the present invention preferably has a wettability gradient along the thickness direction of the bank. Wetting properties in banks are mainly determined by the concentration of fluorine atoms. Therefore, the wettability gradient along the bank thickness direction is obtained by generating a fluorine concentration gradient along the bank thickness direction.

As will be described later, the bank of the present invention can be formed by baking (heat treating) a film of a fluororesin-containing composition patterned in a desired shape. The present inventor has found that a gradient of fluorine concentration can be generated along the thickness direction of the bank by forming the bank formed by the baking process into a forward taper shape.

In the present invention, the fluorine atom concentration on the upper surface of the bank is preferably 5 to 10 atom%, and the fluorine concentration on the bottom surface of the bank is preferably 0 to 3 atom%. Fluorine atom concentration can be measured with an X-ray photoelectron spectroscopy analyzer (also referred to as XPS or ESCA).

Hereinafter, the mechanism by which the gradient of the fluorine concentration is generated along the thickness direction of the bank will be described. Table 1 is a graph showing the relationship between the thickness of the bank formed by baking (heat treatment) the film of the fluororesin-containing composition and the fluorine concentration on the upper surface of the bank.

<tables num="1"><img file="JP2009123714A_D0001.tif" /></tables>

As shown in Table 1, the thicker the bank, the higher the fluorine concentration on the upper surface of the bank, and the larger the water contact angle and the anisole contact angle (lower wettability).

Further, when the shape of the bank is a forward taper as described above, a gradient occurs in the thickness of the bank on the wall surface thereof. That is, as shown in FIG. 1, the bank thickness decreases in the order of 3a, 3b, and 3c.

As mentioned above, the density of the fluorine component on the top surface of the thin bank is low; the density of the fluorine component on the top surface of the thick bank is high. Therefore, among the forward-tapered banks 3 shown in FIG. 1, the fluorine concentration at the portion indicated by 3a (the thickness of the bank is large) is relatively high, and the portion indicated by 3c (the thickness of the bank is large). The fluorine concentration in (small) is relatively low. Therefore, the fluorine concentration in bank 3 decreases in the order of 3a, 3b, and 3c. In FIG. 1, 1 is a substrate and 2 is an electrode.

In this way, by forming the bank formed by the baking process into a forward taper shape, a gradient of fluorine concentration can be generated in the thickness direction of the bank. Further, by generating a gradient of fluorine concentration in the bank thickness direction, a wettability gradient along the bank thickness direction can be obtained. As a result, the bank upper surface 3a, which has low wettability, plays the original role of the bank by suppressing the leakage of the material of the functional layer defined by the bank; The functional layer (hole transport layer, intermediate layer or organic EL layer) is reliably arranged over the entire region defined by the above, that is, up to the tangent line between the bank and the region.

In this way, the shape of the baked fluororesin bank is made into a forward taper shape, and the wettability of the lower part of the bank is made higher than the wettability of the upper part of the bank, so that the patterned region has a uniform thickness without gaps. A functional layer can be formed. Further, it is possible to control the shape of the formed layer by adjusting the shape of the forward taper shape. For example, by adjusting the taper angle, it is possible to prevent the functional layer from leaking beyond the region defined by the bank.

Further, the shape of the bank may be forward-tapered and may have two inflection points (see FIG. 2). A forward taper with two inflection points makes the hem angle at the bottom of bank 3 gentle. Therefore, the ink containing the functional layer material 4 can be easily applied to the region specified by the bank, and can be applied to the entire surface of the specified area without leaving any residue, and a uniform thin film can be obtained. In FIG. 2, 1 is a substrate and 2 is an electrode.

The organic EL device of the present invention has a cathode electrode layer on the organic EL layer. The material of the cathode electrode layer differs depending on whether it is a bottom emission type or a top emission type. In the case of the top emission type, the cathode electrode needs to be transparent, so it is preferable to form an ITO electrode, an IZO electrode, or the like. It is preferable that a buffer layer or the like is formed between the organic EL layer and the cathode electrode layer. On the other hand, in the case of the bottom emission type, the cathode electrode does not have to be transparent, and an electrode made of any material may be used.

The organic EL device of the present invention may be further sealed with a cover material provided on the surface on which the cathode electrode is formed. The cover material suppresses the ingress of moisture and oxygen.

The organic EL device of the present invention may further have an electrically insulating inorganic film (hereinafter referred to as "inorganic insulating film"). Of course, the inorganic insulating film is electrically insulating, but it is also preferable that the inorganic insulating film has high wettability. An example of the material of the inorganic insulating film is silicon oxide (SiO).₂) And Silicon Nitride (Si)₃N₄), Silicon oxynitride (SiON), etc. are included. The thickness of the inorganic insulating film is preferably 10 nm to 200 nm.

The inorganic insulating film preferably protrudes from the bank to the region defined by the bank (see Fig. 3). Preferably, the inorganic insulating film protrudes from the bank by 5 to 10 μm.

In the present invention, a solution containing the material of the functional layer (hole transport layer or intermediate layer) is applied on the inorganic insulating film protruding from the bank. The highly wettable inorganic insulating film allows the solution to be uniformly applied over the entire region defined by the bank, and a functional layer having a uniform film thickness can be obtained. As described above, in the present invention, a functional layer having a more uniform thickness can be obtained by combining the bank having a wettability gradient in the thickness direction and the inorganic insulating film.

As described above, the organic EL device of the present invention has an inorganic insulating film (optional) protruding from the bank, but the arrangement position of the inorganic insulating film is classified into the following two modes according to the material of the hole transport layer. Can be done. Hereinafter, the shape and arrangement position of the inorganic insulating film will be described separately in two modes.

(1) When the material of the hole transport layer is PEDOT-PSS (see Fig. 3) The inorganic insulating film in this embodiment is arranged on the substrate so as to be in contact with the bottom surface of the hole transport layer (see FIG. 3). By forming the inorganic insulating film so as to be in contact with the bottom surface of the hole transport layer, the film thickness of the hole transport layer made of PEDOT-PSS can be made more uniform.

(2) When the material of the hole transport layer is an oxide such as tungsten oxide (see Fig. 4) In this embodiment, the inorganic insulating film is formed so as to be in contact with the bottom surface of the intermediate layer (see FIG. 4). The inorganic insulating film may be arranged on the hole transport layer (Fig. 4A) or on the substrate as long as it is formed so as to be in contact with the bottom surface of the intermediate layer (Fig. 4B). , May be located on the substrate and below the hole transport layer (Fig. 4C). Since the inorganic insulating film is formed so as to be in contact with the bottom surface of the intermediate layer, the film thickness of the intermediate layer formed by applying the solution containing the material of the intermediate layer within the region defined by the bank becomes more uniform. can do. Further, by arranging the inorganic insulating film between the bank and the hole transport layer (Fig. 4A), the adhesiveness between the bank and the hole transport layer composed of the oxide is enhanced.

2. About organic EL display panel A plurality of organic EL elements of the present invention may be arranged in a matrix on one substrate to form an organic EL display panel (see FIG. 5).

The organic EL display panel of the present invention includes a substrate, an anode electrode, a cathode electrode, and an organic EL element having a hole transport layer, an intermediate layer, and a light emitting layer sandwiched between both electrodes. Further, the organic EL display panel of the present invention has a bank.

The organic EL display panel of the present invention basically has the above-mentioned organic EL elements arranged in a matrix on a substrate, but has an anode electrode, a bank, a hole transport layer, an intermediate layer, an organic EL layer, and a cathode electrode. Is characterized by having the following shapes.

Anode electrode When the organic EL display panel is a passive matrix type, a plurality of anode electrodes are formed in a line shape. The line-shaped anode electrodes are preferably parallel to each other. When the organic EL display panel is an active matrix type, a plurality of anode electrodes are formed on the substrate in a matrix shape (for each organic EL element).

bank A plurality of banks are formed in a line shape on the substrate, and a line-shaped region is defined on the substrate (see FIG. 5). The line-shaped banks are preferably parallel to each other. When the anode electrode is line-shaped, it is preferable that the direction of the line of the line-shaped bank and the direction of the line of the anode electrode are orthogonal to each other. A plurality of organic EL elements arranged in a row are arranged in one line-shaped region defined by the line-shaped bank. A solution containing the material of the functional layer is sequentially applied to the line-shaped region. Hereinafter, the line-shaped region defined by the line-shaped bank is referred to as a coating region.

Hole transport layer In the organic EL display panel of the present invention, the hole transport layer is arranged for each organic EL element. That is, the hole transport layer is formed in a matrix (see FIG. 6). Further, the hole transport layer is formed in the above-mentioned coating region.

Middle layer The intermediate layer is arranged over a plurality of organic EL elements in one coating region. That is, the intermediate layer is formed in a line shape in the coating region.

Organic EL layer The organic EL layer is arranged over a plurality of organic EL elements in one coating region. That is, the organic EL layer is formed in a line shape in the coating region. The organic EL material is appropriately selected so that the desired color development (red R, green G, blue B) is produced from each coating region. For example, a green pixel is placed next to a red pixel, a blue pixel is placed next to a green pixel, and a red pixel is placed next to a blue pixel (see FIG. 5).

Cathode electrode The cathode electrode may be formed on the organic EL layer arranged in each coating region, but is usually formed in a line shape in the coating region (see FIG. 5). Normally, a line-shaped bank serves as a cathode separator so that the cathode electrodes formed in the coating regions adjacent to each other are not energized. The cathode electrodes may not have to be separated for each coating area. That is, if the anode electrode is controlled independently for each pixel electrode as in the active matrix type, the TFT element that drives the pixel electrode is independent, so that the cathode electrode can be shared by a plurality of coating regions. it can.

The organic EL display panel of the present invention may have an inorganic insulating film protruding from the bank into the coating region. When the material of the hole transport layer is PEDOT-PSS, the inorganic insulating film is arranged so as to be in contact with the bottom surface of the hole transport layer. When the material of the hole transport layer is an oxide such as tungsten oxide, the inorganic insulating film is arranged so as to be in contact with the bottom surface of the intermediate layer.

The organic EL display panel of the present invention may have a second bank that defines a pixel area within the coating area (see FIG. 7). Here, the pixel region means an opening in one organic EL element. The height of the second bank from the substrate may be the same as the height of the line-shaped bank from the substrate, but is preferably lower than the height of the line-shaped bank from the substrate. The height of the second bank from the substrate is preferably 0.1 to 0.5 μm.

The material of the second bank is not particularly limited as long as it is insulating, but it is preferably an insulating resin. The material of the second bank may or may not contain fluororesin. Therefore, the material of the second bank may be a non-fluorine-based resin (non-fluorine-based polyimide resin, non-fluorine-based polyacrylic resin, etc.).

The second bank, which defines the pixel area, is provided with a groove that communicates the adjacent pixel areas with each other (see FIG. 7). The width of the groove is preferably 10 to 30 μm, more preferably 18 to 22 μm.

The placement position and function of the second bank differ depending on the material of the hole transport layer. Hereinafter, the arrangement position of the second bank will be described separately for the case where the material of the hole transport layer is PEDOT-PSS and the case where the material is an oxide such as tungsten oxide.

(1) When the material of the hole transport layer is PEDOT-PSS. When the material of the hole transport layer is PEDOT-PSS, the second bank defines the region of the hole transport layer. That is, when the material of the hole transport layer is PEDOT-PSS, the second bank prevents the solution from invading the adjacent pixel region when the solution containing PEDOT-PSS is applied to the coating region. It has the function of defining the hole transport layer in a matrix.

(2) When the material of the hole transport layer is an oxide such as tungsten oxide. When the material of the hole transport layer is an oxide, the second bank defines the regions of the intermediate layer and the organic EL layer. In this case, the second bank has a function of improving the yield.

In the manufacturing process of the organic EL display of the present invention, dust may adhere to the coating region before the intermediate layer or the organic EL layer is formed. As will be described later, since the intermediate layer and the organic EL layer are formed by applying the material, when the material of the intermediate layer or the organic EL layer is applied in the coating area to which dust has adhered, the applied material is released. It is sucked by dust, and an intermediate layer or an organic EL layer is not formed in the coating area. On the other hand, when a second bank defining a plurality of pixel areas is arranged in the coating area, the second bank blocks the material of the coated intermediate layer or organic EL layer from being sucked by dust. To do. As a result, even if dust adheres to the coated region, a region in which the intermediate layer or the organic EL layer is not formed is less likely to occur in the coated region. Therefore, the second bank that defines the intermediate layer and the organic EL layer contributes to the improvement of the yield.

In addition, the second bank can suppress electrical crosstalk between pixels. Further, since the second bank is provided with a groove for communicating the pixel regions with each other, the solution containing the material of the intermediate layer or the organic EL layer can move between the pixel regions, and the intermediate layer or the organic EL formed. The layer thickness is leveled within the coating area.

3. About the manufacturing method of organic EL display panel The organic EL display panel of the present invention can be manufactured by any method as long as the effects of the present invention are not impaired. Further, it is preferable that the organic EL display panel of the present invention has a different manufacturing method depending on the material of the hole transport layer. Hereinafter, the case where the hole transport layer is PEDOT-PSS and the case where it is an oxide such as tungsten oxide will be described separately.

(1) When the material of the hole transport layer is PEDOT-PSS. When the hole transport layer is PEDOT-PSS, the method for manufacturing an organic EL display panel of the present invention is as follows: 1) a step of forming an anode electrode on a substrate, and 2) a bank containing a line-shaped fluororesin on the substrate. , A step of forming the anode electrode so as to be exposed and defining a line-shaped region (coating region), 3) a step of forming a matrix-shaped hole transport layer on the substrate, 4) in the coating region, It is preferable to include a step of forming a line-shaped intermediate layer, 5) a step of forming a line-shaped organic EL layer in the coating region, and 6) a step of forming a cathode electrode on the organic EL layer.

The present manufacturing method may further include a step of forming an inorganic insulating film between the steps 1) and 2). The inorganic insulating film is formed by, for example, a plasma CVD method or a sputtering method.

1) In the step, the anode electrode may be formed by forming a conductive thin film on a substrate and patterning it by photolithography or etching, but the method is not particularly limited.

2) In the step, the linear bank is formed using photolithography technique or printing technique.

When forming a bank containing a fluororesin using photolithography technology, a) a step of forming a film of a photosensitive resin composition containing a fluororesin on a substrate on which an anode electrode is formed, b) the film is applied. It comprises a step of exposing and developing to expose a part or all of the anode electrode. In order to form a film of a photosensitive resin composition containing a fluororesin on a substrate surface on which an anode electrode is formed, for example, the resin composition is coated from the resin composition by using a technique such as spin coating, die coating, or slit coating. A film is formed; the formed film may be dried. The drying conditions are not particularly limited, but it may be left at 80 ° C for 2 to 3 minutes.

By exposing and developing a film of the photosensitive resin composition containing a fluororesin, a line-shaped region (coating region) is defined and the anode electrode is exposed. As described above, the shape of the wall surface of the developed film is preferably a forward taper shape as shown in FIGS. 1 and 2. The shape of the wall surface can be controlled by appropriately setting exposure and development conditions.

The developed film is baked. It is presumed that the bake treatment can make the fluorine component of the fluororesin contained in the film emerge on the surface of the film. The baking treatment conditions are not particularly limited, but for example, the temperature is about 200 ° C. or higher, and the time is about 1 hour. This forms a bank with the desired wettability surface. As described above, if the shape of the wall surface is forward-tapered, the wettability of the wall surface can be changed according to the height of the bank.

On the other hand, when a resin film containing a predetermined pattern of fluororesin is formed by using a printing technique, printing may be performed by a method such as intaglio printing or letterpress printing.

Further, in the example of the present manufacturing method, a second bank may be formed in step 2). In this manufacturing method, the second bank defines a hole transport layer. Also, instead of the second bank, a water repellent self-assembled monolayer (SAM) may be formed. Examples of materials for such self-assembled monolayers include silane coupling agents and the like. It is preferable that the self-assembled monolayer defines the pixel region as in the second bank. Further, the self-assembled monolayer is preferably arranged on the inorganic insulating film. Even when the self-assembled monolayer is formed, it is preferable that the pixel regions communicate with each other.

After forming the bank, the substrate and the surface of the anode electrode in the coating region may be washed with ozone water. The cleaning procedure with ozone water is not particularly limited, but the concentration of ozone water may be about 0.02 to 20 ppm. More specifically, ozone water is dropped on the coated area to spin the substrate (about 10 rpm). After spinning for about 2 minutes, water is dropped and isopropyl alcohol is dropped to wash the product while it is still spinning.

By cleaning with ozone water, the bank component adhering to the substrate and the surface of the anode electrode can be appropriately removed without damaging the surface of the baked bank. On the other hand, conventionally, the coated area is irradiated with ultraviolet rays or plasma (for example, oxygen plasma) to improve its wettability, but the irradiation with ultraviolet rays or plasma tends to damage the surface of the baked bank. It was found that the fluorine component of the fluororesin unevenly distributed on the surface was removed. Therefore, in the present invention, it is preferable not to irradiate with ultraviolet rays or plasma.

As described above, by cleaning with ozone water, the bank component (that is, fluororesin) hardly remains on the substrate or the surface of the anode electrode in the coating region. The fact that almost no bank component remains means that, for example, the carbon atom concentration on the substrate or the surface of the anode electrode in the coating region is 20 atom% or less, preferably 15 atom% or less, and more preferably 12 atom% or less. Further, the fluorine atom concentration on the substrate or the surface of the anode electrode in the coating region is preferably 5 atom% or less. The carbon atom concentration and the fluorine atom concentration on the surface of the substrate or the anode electrode may be measured by an X-ray photoelectron spectroscopic analyzer (XPS or ESCA) by removing the laminated functional layer to expose the surface of the substrate or the anode electrode.

3) In the step, the hole transport layer is formed by applying a solution containing PEDOT-PSS, for example, by an inkjet method, a die coating method, a letterpress printing method, or the like to form a matrix-shaped hole transport layer. The hole transport layer is formed on the anode electrode. When the second bank is formed, a matrix-like hole transport layer may be formed by applying a solution containing PEDOT-PSS into the pixel region defined by the second bank.

4) In the step, a line-shaped intermediate layer is formed in the coating area by an inkjet method, a die coating method, a letterpress printing method, or the like.

5) In the step, coat the coating area with an ink containing a line-shaped organic EL material and a solvent. The coating may be performed by using a technique such as inkjet, dispenser, nozzle coating, intaglio printing or letterpress printing. When applying with a dispenser, it is preferable to control the ejection of ink from the dispenser by a suckback operation or the like at the start and end of the line to be applied. The thickness of the applied ink (thickness of the coating film) may be about 1 to 10 μm. Further, the coating film is dried to form a layer containing the organic EL material.

6) In the step, a cathode electrode is formed on the organic EL layer. The cathode electrode may be formed by a vapor deposition method.

(2) When the material of the hole transport layer is an oxide such as tungsten oxide. When the hole transport layer is an oxide such as tungsten oxide, the method for producing an organic EL display panel of the present invention is 1) a step of forming an anode electrode on a substrate, and 2) a matrix-like hole transport on the substrate. Steps of forming a layer, 3) A bank containing a line-shaped fluororesin on a substrate is formed so that the hole transport layer is exposed, and a coating area is defined. 4) A line-shaped bank is formed in the coating area. It is preferable to include a step of forming the intermediate layer of the above, 5) a step of forming an organic EL layer in the coating region, and 6) a step of forming a cathode electrode on the organic EL layer.

The present manufacturing method may have a step of forming an inorganic insulating film between the 2) step and the 3) step.

In this manufacturing method, the step of forming the anode electrode on the substrate surface, the step of forming the line-shaped intermediate layer and the organic EL layer, and the step of forming the cathode electrode are the same steps as the manufacturing method of (1) above. , You can do it by the same means.

2) In the step, a matrix-like hole transport layer made of an oxide such as tungsten oxide is formed on the substrate. The matrix-shaped hole transport layer may be patterned in a matrix by etching or the like after forming a layer made of an oxide such as tungsten oxide on the substrate by a sputtering method or a heat-deposited method. The hole transport layer is formed on the anode electrode.

3) In the step, a bank containing a line-shaped fluororesin is formed on the substrate on which the anode electrode and the hole transport layer are formed, and the hole transport layer is exposed. The bank forming method may be the same as the bank forming method in the manufacturing method (1). Further, a second bank may be formed at the same time as or after the bank containing the linear fluororesin is formed. In this manufacturing method, the second bank defines the region of the intermediate layer and the organic EL layer. Also, a self-assembled monolayer may be formed in place of the second bank.

Further, after the bank is formed, the exposed hole transport layer may be washed with ozone water. The cleaning method with ozone water may be the same as the cleaning method with ozone water in the production method (1).

By cleaning with ozone water, almost no bank component (that is, fluororesin) remains on the substrate or the surface of the hole transport layer in the coating area. The fact that almost no bank component remains means that, for example, the carbon atom concentration on the substrate or the surface of the hole transport layer in the coating region is 20 atom% or less, preferably 15 atom% or less, and more preferably 12 atom% or less. Further, it is preferable that the fluorine atom concentration on the surface of the substrate or the hole transport layer in the coating region is 5 atom% or less. The carbon atom concentration and fluorine atom concentration on the surface of the substrate or hole transport layer are measured by an X-ray photoelectron spectroscopic analyzer (XPS or ESCA) by removing the laminated functional layer to expose the surface of the substrate or hole transport layer. do it.

In the 4) step, an intermediate layer is formed in the line-shaped coating region, and in the 5) step, an organic EL layer is formed in the line-shaped coating region. The method for forming the intermediate layer and the organic EL layer may be the same as the method for forming the intermediate layer and the organic EL layer in the production method (1). When the second bank is formed, the method of forming the intermediate layer and the organic EL layer involves applying a solution containing the materials of the intermediate layer and the organic EL layer to the pixel region defined by the second bank. Including.

4. About organic semiconductor devices The organic semiconductor device of the present invention has a substrate, a source electrode, a drain electrode, and an organic semiconductor layer.

The source and drain electrodes can be placed facing each other through a gap. The gap distance between the source electrode and the drain electrode is usually several μm. The material of the source electrode and the drain electrode is not particularly limited, and may be a conductive metal, a conductive polymer, or the like. Examples of conductive metals include molybdenum Mo, tungsten W, aluminum Al, chromium Cr, titanium Ti, gold Au, and alloys thereof. The source electrode and the drain electrode may be a multilayer metal film of a different type of metal.

A semiconductor layer (channel) containing an organic semiconductor material covers a region connecting the source electrode and drain electrode on the substrate and both electrodes. Examples of organic semiconductor materials include low molecular weight organic semiconductor materials such as pentacene, tetracene and phthalocyanine compounds, high molecular weight organic semiconductor materials such as polythiophene and polyphenylene vinylene, and carbon nanotubes. The organic semiconductor device of the present invention preferably has a polymer-based organic semiconductor material.

The semiconductor layer is preferably formed by applying a polymer-based organic semiconductor material within a region defined by a bank.

The bank that defines the semiconductor layer is characterized by containing a fluororesin like the organic EL element. The material of the bank in the semiconductor element of the present invention may be the same as the material of the bank in the organic EL element. Further, the bank preferably has a wettability gradient along the thickness direction of the bank. That is, it is preferable that the wettability of the upper surface of the bank is low and the wettability of the bottom surface of the bank is high. The wettability gradient along the thickness direction of the bank can be obtained by making the shape of the bank formed by the baking process into a forward taper shape as described above.

As a result, the ink containing the material of the semiconductor layer applied in the region defined by the bank can be appropriately applied to the end of the bank, and the semiconductor layer having a uniform thickness can be obtained. Thereby, the channel characteristics of the semiconductor layer can be improved.

Further, after the formation of the bank and before the formation of the semiconductor layer, the electrodes and the substrate exposed in the region defined by the bank may be washed with ozone water. The cleaning method with ozone water may be the same as the cleaning method with ozone water in the method for manufacturing the organic EL display panel. By cleaning with ozone water, a semiconductor layer can be formed on a cleaner electrode surface.

In the organic semiconductor of the present invention, a gate electrode for controlling a channel which is an organic semiconductor layer is arranged. The gate electrode may be a back gate electrode, a top gate electrode, or another type of gate electrode. If it is an organic semiconductor device, an overcoat layer that protects the organic semiconductor layer may be further arranged.

[Embodiment 1] In the first embodiment, the organic EL device of the present invention will be described. FIG. 2 shows an example of the organic EL device of the present invention. The organic EL device shown in FIG. 2 has a substrate 1, an anode electrode 2, a bank 3, a hole transport layer 4, an intermediate layer 5, an organic EL layer 6, and a cathode electrode 7.

As described above, when the organic EL element is of the bottom emission method, the material of the substrate 1 and the anode electrode 2 is preferably transparent; when the organic EL element is of the top emission method, the material of the cathode electrode 7 is transparent and the anode electrode is used. It is preferable that the material of 2 is a material having strong light reflectivity. Further, the work function of the surface of the anode electrode 2 in contact with the hole transport layer 4 is preferably controlled to 5.1 to 5.5 eV. This is to facilitate the injection of holes. The work function of a metal anode electrode means the minimum energy required to extract an electron from the surface of the electrode to the outside.

The hole transport layer 4, the intermediate layer 5, and the organic EL layer 6 are preferably made of a polymer-based organic material. This is because it is preferable that both layers are formed by a coating method.

Bank 3 is characterized by containing a fluororesin. The color of bank 3 is not particularly limited, but may be black. Brightness can be increased by using a bank of a color (for example, black) having a high contrast with the light emitted from the light emitting layer.

As shown in FIG. 2, since the wall surface of the bank 3 has a forward taper shape, the wettability of the lower part of the bank is high and the wettability of the upper part of the bank is low as described above. Further, the bank 3 has a forward tapered wall surface and has two inflection points. That is, the contact angle of the bank 3 with respect to the anode electrode 2 is gentle. Therefore, especially when the hole transport layer 4 is to be produced by the coating method, the ink containing the hole injection material can be appropriately applied to the end of the bank, and the layer tends to have a uniform thickness. .. Therefore, it becomes easy to emit light from the entire surface of the light emitting layer, and the aperture ratio is increased.

[Embodiment 2] In the second embodiment, an active matrix type organic EL display panel will be described. Further, in the present embodiment, the material of the hole transport layer is PEDOT-PSS.

FIG. 5 is a plan view of an active matrix type organic EL display panel. In the panel shown in FIG. 5, a plurality of banks 3 formed in a line shape are arranged. Bank 3 defines the coating area 10. The coating area 10 is classified into a coating area 10R that emits red light; a coating area 10G that emits green light; and a coating area 10B that emits blue light, and is arranged in order. The coating area 10 is covered with the cathode electrode 7. The cathode electrode 7 is separated by the bank 3 for each coating region 10.

Bank 3 is characterized by containing a fluororesin. The color of bank 3 is not particularly limited, but may be black. Brightness can be increased by using a bank of a color (for example, black) having a high contrast with the light emitted from the light emitting layer. Although not shown, the shape of the bank is preferably a forward taper shape.

FIG. 6 is a plan view of the active matrix type organic EL display panel of the present embodiment in which the cathode electrode, the organic EL layer, and the intermediate layer are removed. As shown in FIG. 6, the hole transport layer 4 is arranged in the pixel region 11 defined by the second bank 3'. As a result, the hole transport layer 4 is arranged in a matrix on the substrate 1. Further, the second bank 3'has a groove that communicates the pixel regions 11 with each other.

FIG. 7A shows a cross-sectional view of line AA of the organic EL display panel of the present embodiment shown in FIG. FIG. 7B shows a cross-sectional view of line BB of the organic EL display panel of the present embodiment shown in FIG.

As shown in FIG. 7A, the inorganic insulating film 8 is arranged so as to be in contact with the bottom surface of the hole transport layer 4. When the hole transport layer 4 is formed by applying PEDOT-PSS to the pixel region 11 by the inorganic insulating film 8, the film thickness of the hole transport layer 4 is made more uniform.

As shown in FIG. 7B, the hole transport layer 4 is independently arranged on each anode electrode 2 so as to cover the anode electrode 2. On the other hand, the intermediate layer 5 and the organic EL layer 6 are arranged over a plurality of organic EL elements in the coating region 10.

[Embodiment 3] In the second embodiment, the organic EL display panel in which the material of the hole transport layer is PEDOT-PSS has been described. In the third embodiment, an organic EL display panel in which the material of the hole transport layer is an oxide such as tungsten oxide will be described.

The plan view of the organic EL display panel of the present embodiment is the same as the plan view of the organic EL display panel of the second embodiment. Therefore, FIG. 5 is also a plan view of the present embodiment.

FIG. 8A shows a cross-sectional view of line AA of the organic EL display panel of the present embodiment shown in FIG. FIG. 8B shows a cross-sectional view of line BB of the organic EL display panel of the present embodiment shown in FIG.

As shown in FIGS. 8A and 8B, the organic EL display panel of the present embodiment is the same as the organic EL display panel of the second embodiment except for the arrangement position of the inorganic insulating film 8. Therefore, the same members as those of the organic EL display panel of the second embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 8A, in the organic EL display panel of the present embodiment, the inorganic insulating film 8 is arranged so as to be in contact with the bottom surface of the intermediate layer 5. In the present embodiment, since the material of the hole transport layer is an oxide such as tungsten oxide, the hole transport layer is not formed by the coating method. Therefore, in the present embodiment, the inorganic insulating film 8 plays a role of making the film thickness of the intermediate layer 5 formed by the coating method uniform.

[Embodiment 4] In the fourth embodiment, the organic semiconductor device will be described. FIG. 9 shows an example of the organic semiconductor device of the present invention. The organic semiconductor element shown in FIG. 9 is a so-called backgate type thin film transistor, which comprises a substrate 21, a backgate electrode 22, a source electrode 23, a drain electrode 24, a bank 25, an organic semiconductor layer 26, and an overcoat layer 27. Have. Of course, the organic semiconductor device of the present invention may be of the top gate type.

The bank 25 is characterized by containing a fluororesin. Similar to FIG. 2, the bank 25 shown in FIG. 9 has a forward-tapered wall surface, so that the wettability of the lower part of the bank is high and the wettability of the upper part of the bank is low. Further, the bank 25 has a forward tapered wall surface and has two inflection points. That is, the contact angle of the bank 25 with respect to the source electrode 23 and the drain electrode 24 is gentle. Therefore, when the organic semiconductor layer 26 is to be produced by the coating method, the ink containing the organic semiconductor material can be appropriately applied to the end of the bank, and the layer tends to have a uniform thickness and is thinned. Is also possible. Therefore, the channel characteristics of the organic semiconductor layer 26 are improved (including the improvement of mobility and the improvement of ON / OFF ratio).

This application claims priority under Japanese Patent Application No. 2007-145877 filed May 31, 2007. All the contents described in the application specification are incorporated in the application specification.

The organic EL device of the present invention appropriately exerts the function of the organic functional layer. That is, the thickness of the functional layer can be made constant, and the functional deterioration due to impurities such as bank components is suppressed. The organic device of the present invention can be used, for example, as an organic semiconductor device, an organic EL device, or the like.

<figref num="1">It is a figure which shows the organic EL element which has a forward taper bank.</figref><figref num="2">It is a figure which shows the organic EL element which has a forward taper shape and has a bank with two inflection points.</figref><figref num="3">It is a figure of the organic EL element which has an inorganic insulating film.</figref><figref num="4">It is a figure of the organic EL element which has an inorganic insulating film.</figref><figref num="5">It is a top view of the organic EL display panel of this invention.</figref><figref num="6">It is a top view which excluded the cathode electrode, the organic EL layer and the intermediate layer from the organic EL display panel of this invention.</figref><figref num="7A">It is sectional drawing of the organic EL display panel of this invention.</figref><figref num="7B">It is sectional drawing of the organic EL display panel of this invention.</figref><figref num="8A">It is sectional drawing of the organic EL display panel of this invention.</figref><figref num="8B">It is sectional drawing of the organic EL display panel of this invention.</figref><figref num="9">It is a figure which shows the organic semiconductor element of this invention.</figref>

1 board 2 Anode electrode 3 banks 3'second bank 4 hole transport layer 5 middle layer 6 Organic EL layer 7 Cathode electrode 8 Inorganic insulating film 10 Coating area 11 pixel area 20 Organic semiconductor devices 21 board 22 Gate electrode 23 Source electrode 24 Drain electrode 25 banks 26 Organic semiconductor layer 27 Overcoat layer