WO2011158291A1

WO2011158291A1 - Organic light-emitting element production method

Info

Publication number: WO2011158291A1
Application number: PCT/JP2010/004009
Authority: WO
Inventors: 南野裕隆
Original assignee: パナソニック株式会社
Priority date: 2010-06-16
Filing date: 2010-06-16
Publication date: 2011-12-22

Abstract

Disclosed is a method for stable production of an organic light-emitting element with low drive voltage and good luminous efficiency, by reducing bank material residue while ensuring liquid repellency of bank surfaces. To achieve this, a photosensitive resist material that has a fluorine component and a resin component is used as the bank material, and banks (5) are formed on a hole injection layer. An ultra-violet light with a light vibration energy of 458 to 472 kJ/mol is irradiated from the top of a substrate where the banks (5) are formed. The irradiation time is set such that the total irradiated UV light volume (cumulative light volume) is 690 to 1,035 mJ/cm². Hole transport layers are formed in concave sections between the banks (5) by filling the concave sections with an ink that includes a hole transport layer material, and drying same. The concave sections between the banks (5) are also filled with an ink that includes an organic light-emitting material, which is then dried under reduced pressure and baked to form a light-emitting layer.

Description

Manufacturing method of organic light emitting device

The present invention relates to a method for manufacturing an organic light emitting device, and more particularly to a method for manufacturing an organic light emitting device by applying an ink for forming a functional layer and a light emitting layer between banks.

An organic electroluminescence element (hereinafter referred to as “organic EL element”), which has been researched and developed in recent years, is a light-emitting element utilizing an electroluminescence phenomenon of an organic material, and includes a lower electrode (anode) and an upper part. A light emitting layer is interposed between the electrode (cathode). Such organic EL elements are arranged in a matrix to form an organic EL display.

In such an organic EL display structure, generally, pixels are partitioned by a bank made of an insulating material, and the shape of the light emitting layer is defined by the bank. In addition, a hole injection layer, a hole transport layer, or a hole injection / transport layer is interposed between the lower electrode and the light emitting layer as necessary, and electrons are also inserted between the upper electrode and the light emitting layer as necessary. An injection layer, an electron transport layer, or an electron injection / transport layer is interposed. Hereinafter, since the lower electrode, the hole injection layer, the electron injection layer, and the upper electrode perform specific functions of injecting charges, these layers are referred to as “functional layers”.

Such an organic EL display includes a step of forming a functional layer including a lower electrode, a bank forming step of forming a bank that partitions adjacent pixel portions on the functional layer, and an ink including an organic light emitting material. It is produced through a step of forming a light emitting layer for forming an organic light emitting layer and a step of forming an upper electrode above the organic light emitting layer.

In the process of forming the light-emitting layer, in addition to the method of forming a low molecular material by a vacuum process, the ink (coating liquid) in which the material is dissolved in a solvent is filled between the banks by an inkjet method or the like. Many wet methods for drying ink are also used.

In this wet method, a solvent having a relatively high boiling point is used as a solvent so that each opening is filled with an equal amount of ink, and when the filled ink is dried, the solvent having a high boiling point is evaporated. Therefore, the substrate filled with ink is dried under reduced pressure in a dryer.

It is also important to increase the liquid repellency of the bank surface with respect to the ink, that is, to increase the contact angle of the ink with respect to the bank surface, in order to form the light emitting layer with high accuracy. Therefore, for example, it has also been proposed to form a bank using a fluorinated photoresist (Patent Document 1). In this way, when a bank is formed by applying a fluorinated photoresist and a photolithographic process such as development, washing, and baking, the liquid repellency of the bank surface is increased, so that the light emitting layer is uniformly formed on the entire panel. Can do.

JP 2005-522000 Gazette JP 2009-117392 A JP 2004-314056 A

In such an organic EL element, it is desired to lower the driving voltage and to improve the luminous efficiency.

However, as described above, when a bank is formed by a photoresist method in which a photosensitive bank material is applied, and the applied photosensitive bank material is exposed and patterned, the driving voltage of the organic light emitting element is increased, Luminous efficiency tends to decrease, and it is difficult to stably obtain an organic light emitting device having low driving voltage and good luminous efficiency.

As described above, the driving voltage of the organic light emitting device is increased or the light emission efficiency is decreased because the residue of the bank material remains on the bottom surface of the opening between the banks, and the charge injection characteristic of the functional layer is the residue of the bank material. It is thought that it is inhibited by.

To solve such a problem, for example, as disclosed in Patent Documents 2 and 3, by forming a bank and then treating with O2 plasma or irradiating with UV light, the bottom of the opening between the banks is formed. There is also a method of removing the residue remaining in the substrate, but O2 plasma treatment and UV light irradiation have a problem that the contact angle of the bank is lowered and the ink overflows, making it difficult to form the light emitting layer with a wet method with high accuracy. .

In view of such a problem, the present invention can stably produce an organic light emitting device having a low driving voltage and good luminous efficiency by reducing the residue of the bank material while ensuring the liquid repellency of the bank surface. It aims to provide a method.

In order to solve the above-described problem, in the method for manufacturing an organic light-emitting element which is one embodiment of the present invention, a first step of preparing a substrate, and a second step of forming a functional layer including a lower electrode above the substrate, A photosensitive resist material containing a fluorine component and a resin component is applied above the functional layer, and the photosensitive resist material is exposed and patterned to form openings corresponding to the pixel portions and adjacent pixels. A third step of forming a bank for partitioning the part, a fourth step of irradiating the opening and the bank with ultraviolet light, and after the fourth step, an ink containing an organic light emitting material is applied to the opening. A fifth step of forming an organic light emitting layer and a sixth step of forming an upper electrode above the organic light emitting layer. In the fourth step, the vibration energy of light is 458 to 472 kJ / mol. Using ultraviolet as the circumference, the sum of the amount of light to be irradiated (integrated light quantity) is decided to irradiation so that 690 ~ 1035mJ / cm ^2.

The above "vibration energy of light" refers to the energy E of photons and is obtained from the wavelength of light.

E = h × c / λ (c is the speed of light in vacuum, h: Planck's constant 6.626 × 10 ⁻³⁴ [J s])

According to the above aspect, in the fourth step, the total amount of light to be irradiated (integrated light amount) is 690 to 1035 mJ / cm ² using ultraviolet light having a vibration energy of light in the range of 458 to 472 kJ / mol. Since the opening and the bank are irradiated, the residue of the bank material can be reduced while ensuring the liquid repellency of the bank surface.

Therefore, the organic light emitting layer can be accurately formed in the fifth step, and the bank residue is reduced. As a result, favorable light emission characteristics (an improvement in light emission efficiency, a decrease in driving voltage, and a longer life) can be obtained as an organic light emitting device. That is, uniform light emission characteristics can be obtained throughout the panel, and good light emission characteristics as an organic light emitting device can be obtained.

The mechanism by which the above effect can be obtained is estimated as follows.

Through the first to third steps, a part of the bank constituent materials (fluorine component and resin material) remains as a residual component on the functional layer in the opening between the banks. If the light emitting layer is formed in the opening between the banks while the residual component remains, the charge injection characteristic of the functional layer is deteriorated.

On the other hand, according to the aspect, in the fourth step, the resin is mainly used as a residual component remaining on the functional layer of the opening by irradiating the opening and the bank with the ultraviolet light having the vibration energy in the specific range. The binding of the components is dissociated and the residual components are reduced. And since a light emitting layer is formed in the opening part between banks in the state in which the residual component was reduced, the fall of a charge injection characteristic is suppressed.

Moreover, since the ultraviolet rays irradiated in the fourth step have energy in the above range and the integrated light amount is also irradiated in the above range, the bond of the fluorine component is not actively dissociated. Therefore, the bond of fluorine components on the bank surface is not damaged by ultraviolet rays, and the liquid repellency of the bank surface is maintained.

As described above, when the opening is filled with ink containing an organic light emitting material in the fifth step, the ink does not overflow from the opening, and the organic light emitting layer can be formed satisfactorily.

In addition, since the bond of the fluorine component is not actively dissociated as described above, the fluorine component in the residual component remains, but the effect of preventing the functional layer from being deteriorated by reducing the resin component is Fully obtained.

It is process drawing explaining the manufacturing method of the organic electroluminescent display concerning embodiment. It is process drawing explaining the bank formation process and UV cleaning process concerning embodiment. It is process drawing explaining the manufacturing method of the organic electroluminescent display concerning embodiment. It is process drawing explaining the manufacturing method of the organic light emitting display apparatus concerning embodiment. It is a table | surface which shows the vibration energy of the light of various molecules and the light of various lamps. It is a figure which shows the mode of the residue and bank surface when UV light is irradiated from on a bank. It is a graph which shows the measurement result of the fluorine remaining amount after a UV washing process. It is a graph which shows the result of having measured the contact angle with respect to the bank surface of an ink after a UV washing | cleaning process. It is a graph which shows the result of having measured the relationship between the current density-luminous efficiency about an element sample. It is a graph which shows the result of having measured the relationship between a drive voltage and current density about an element sample. It is a graph which shows the result of having measured luminance over time about an element sample. It is a graph which shows the result of having measured the drive voltage over time about the element sample.

In the method for manufacturing an organic light-emitting element which is one embodiment of the present invention, a first step of preparing a substrate, a second step of forming a functional layer including a lower electrode above the substrate, and above the functional layer, By applying a photosensitive resist material containing a fluorine component and a resin component, and exposing and patterning the photosensitive resist material, an opening corresponding to the pixel portion is formed and a bank that partitions adjacent pixel portions is formed. After the third step, the fourth step of irradiating the opening and the bank with ultraviolet rays, and after the fourth step, the organic light emitting layer is coated with an ink containing an organic light emitting material and dried. And a sixth step of forming the upper electrode above the organic light emitting layer. In the fourth step, ultraviolet light having a vibration energy of light in the range of 458 to 472 kJ / mol is used. Sum morphism that amount (integrated light quantity) is decided to irradiation so that 690 ~ 1035mJ / cm ^2.

According to this aspect, the organic light emitting layer can be formed with high accuracy and the residue of the bank material is reduced, so that the organic light emitting device has good light emission characteristics (improvement of light emission efficiency, decrease in driving voltage, and longer life). can get.

In the above aspect, the following is preferable.

The vibration energy of the ultraviolet light irradiated in the fourth step is set to be larger than the maximum value of the bond dissociation energy of the resin component and smaller than the minimum value of the bond dissociation energy of the fluorine component.

The integrated light quantity in the fourth step is represented by the product of the illuminance and the irradiation time. The illuminance is set in the range of 5 to 150 mW / cm ² and the irradiation time is set to 5 to 200 seconds.
In the second step, a hole injection layer (HIL) containing tungsten oxide (WOx) is used as the functional layer, and the normalized ionic strength of the fluorine component on the functional layer after the fourth step (standardized with reference to the tungsten oxide component). Value) is 3.0 × 10 ⁰ or more and 1.0 × 10 ¹ or less.

The normalized ionic strength of the fluorine component in the bank after the fourth step is 0.3 or more and less than 1 with respect to the normalized ionic strength of the fluorine component in the bank after the third step. To do. By doing so, the residual amount of the fluorine component does not change greatly before and after the UV irradiation, so that the liquid repellency of the bank surface is maintained.

In the fourth step, the contact angle of the ink containing the organic light emitting material with respect to the bank after being irradiated with ultraviolet rays is set to 35 ° to 60 °. If it does so, in an 5th process, since an ink does not overflow easily from an opening part, an organic light emitting layer can be formed favorably.

When the functional layer includes a hole injection layer (hole injection layer), the resin material diffused from the bank to the hole injection layer in the third step by irradiating the opening with ultraviolet rays in the fourth step. Remove.

An organic light emitting display device can be constituted by the organic light emitting device manufactured by the above manufacturing method and a drive circuit for driving the organic light emitting device.

In the method for manufacturing an organic light-emitting element which is one embodiment of the present invention, a first step of preparing a substrate, a second step of forming a functional layer including a lower electrode above the substrate, and an upper portion of the functional layer In addition, a photosensitive resist material containing a fluorine component and a resin component is applied, and the photosensitive resist material is exposed and patterned to form an opening corresponding to the pixel portion and to partition adjacent pixel portions. After the fourth step of irradiating the opening and the bank with ultraviolet light, and after the fourth step, an ink containing an organic light-emitting material is applied to the opening and dried. A fifth step of forming the light emitting layer and a sixth step of forming the upper electrode are provided above the organic light emitting layer. In the fourth step, the vibration energy of the ultraviolet light is determined from the dissociation energy of the resin component used. The value is larger and smaller than the dissociation energy of the fluorine component to be used. Further, the total amount of light to be irradiated (integrated light amount) is the normalized ion intensity of the fluorine component in the bank after the fourth step. The ratio value was 0.3 or more and less than 1 with respect to the normalized ionic strength of the fluorine component in the later bank.

Also according to this embodiment, uniform light emission characteristics can be obtained throughout the panel, and good light emission characteristics as an organic light emitting device can be obtained.

Here, the dissociation energy of the resin material is 335 to 457 kJ / mol, the dissociation energy of the fluorine component is 472 to 524 kJ / mol, the vibration energy of the ultraviolet light is 458 to 472 kJ / mol, and the integrated light quantity is 690 to 1035 mJ / cm ^2. It is preferable that

[Embodiment]
[Background of obtaining one embodiment of the present invention]
Hereinafter, prior to specific description of the embodiments of the present invention, the background for obtaining the embodiments of the present invention will be described.
(i) Conventional:
Conventionally, as described in [Background Art] above, when a bank is formed by a photoresist method in which a photosensitive bank material containing a fluorine component is applied, and the applied bank material is exposed and patterned, the organic light emitting device There was a tendency for the drive voltage to increase and the luminous efficiency to decrease.
This is thought to be because the residue of the bank material remains on the bottom of the opening between the banks and adheres to the surface of the functional layer, and the charge injection characteristics of the functional layer are hindered by the residue of the bank material. Yes.
One of the causes is that among the residual components of the bank material, a highly reactive and strong oxidizing fluorine component chemically modifies the functional layer and affects the charge injection characteristics. Is considered.
For this reason, for example, attempts have been made to positively remove the fluorine component in the residual component by irradiating with UV light (ultraviolet light).
(ii) Consideration:
As a result of studying the above points, the present inventor has found that when the energy of UV light is increased in order to reliably remove the fluorine component adhering to the functional layer, the fluorine component adhering to the functional layer can be removed, but it is contained in the bank. It has also been found that the fluorine component that has been removed is also removed and the liquid spillability of the bank may be reduced.
On the other hand, if the energy of the UV light is reduced in order to maintain the content of the fluorine component in the bank, the fluorine component adhering to the functional layer cannot be removed sufficiently, and the charge injection characteristics may still be deteriorated. is there.
As described above, as long as the purpose is to surely remove the fluorine component adhering to the functional layer, an effective solution for the solution using UV light has not been found.
At this point, the present inventor tried to change the idea, and the decrease in the charge injection characteristics of the functional layer was not caused mainly by the fluorine component itself in the residue component, but the entire residue component (in addition to fluorine). It was estimated that there was a main cause for the amount of resin component) attached.
Specifically, by focusing on the resin component (CH) in the residual component adhering to the functional layer and removing this resin component, the total amount of the residual component is reduced and the charge injection characteristics are reduced. I guessed it could be prevented. In this case, it is confirmed that the energy of the UV light for removing the resin component is smaller than the energy of the UV light for removing the fluorine component. In the case of removing the resin component, it was thought that the fluorine component contained in the bank can be left by setting the irradiation time appropriately.

As a result of accumulating the above considerations, the present inventor removes the resin component adhering to the functional layer by using UV light having a “predetermined energy range” and prevents the charge injection characteristics of the functional layer from deteriorating. At the same time, by irradiating this UV light for “predetermined time”, the inventors have reached the technical idea of the present invention in which the fluorine component contained in the bank is left and the lyophobicity of the bank is maintained. Through further experimental confirmation, the specific solution means according to the present invention was obtained and the effects were confirmed.
<Method for manufacturing organic EL display>
1 to 3 are process diagrams illustrating a method for manufacturing an organic EL display according to an embodiment of the present invention.

Prepare the TFT substrate 1.

The TFT substrate 1 includes, for example, alkali-free glass, soda glass, non-fluorescent glass, phosphoric acid glass, boric acid glass, quartz, acrylic resin, styrene resin, polycarbonate resin, epoxy resin, polyethylene, polyester, and silicone. An amorphous TFT (EL element drive circuit) is formed on a base substrate made of an insulating material such as a resin or alumina.

As shown in FIG. 1B, the protective resist covering the TFT substrate 1 is peeled off, an organic resin is spin-coated on the TFT substrate 1, and patterned by PR / PE (photoresist / photoetching). As shown in FIG. 1C, a planarizing film 1a (thickness 4 μm) is formed.

An anode electrode as a lower electrode is formed on the planarizing film 1a.

First, as shown in FIG. 1D, a first anode electrode 2 made of silver-palladium-copper alloy (APC) is formed on the planarizing film 1a. The first anode electrode 2 is formed, for example, by forming a thin film by APC by sputtering and patterning the thin film in a matrix form by PR / PE (thickness 150 nm). The first anode electrode 2 may be formed by vacuum deposition or the like.

Next, as shown in FIG. 1 (e), the second anode electrode 3 is formed in a matrix. The second anode electrode 3 is formed, for example, by forming an ITO thin film by a plasma vapor deposition method and patterning the ITO thin film by PR / PE (thickness 110 nm).

Next, as shown in FIG. 1 (f), a hole injection layer 4 is formed on the second anode electrode 3.

The hole injection layer 4 is formed by sputtering a material that performs a hole injection function, such as metal oxide, metal nitride, or metal nitride, for example, WOx (tungsten oxide) and patterning it with PR / PE (thickness). 40 nm). The hole injection layer 4 is formed not only on the anode electrode but over the entire upper surface of the substrate 1.

The anode electrode and hole injection layer 4 formed as described above correspond to a functional layer. The second anode electrode 3 is interposed between the first anode electrode 2 and the hole injection layer 4 and has a function of improving the bonding property between the layers.

Bank formation process:
As shown in FIG. 1G, a bank 5 is formed on the hole injection layer 4. A region where the bank 5 is formed on the hole injection layer 4 is a region corresponding to a boundary between adjacent light emitting layer formation scheduled regions.

The bank 5 is formed by forming a bank material layer so as to cover the whole of the hole injection layer 4 and removing a part of the formed bank material layer by PR / PE (thickness: 1 μm).

Although FIG. 1 shows a cross-sectional shape of the substrate 1 cut in the horizontal direction, the bank 5 extends along the top surface of the substrate 1 in the vertical direction (the front and back direction in FIG. 1). A plurality of banks 5 are arranged over the entire top surface of the substrate 1.

The bank 5 may be a striped line bank that extends only in the vertical direction, or may be a pixel bank that extends in the vertical and horizontal directions and has a planar shape in the form of a cross.

FIG. 2 is a diagram for specifically explaining the bank formation process.

As shown in FIG. 2 (a), a substrate on which a hole injection layer is formed is put, and a bank material is applied thereon by spin coating as shown in FIG. 2 (b), thereby forming a bank material layer 5a. Form.

As the bank material, a photosensitive resist material containing a fluorine component compound and a resin component material is used. In addition, this bank material is subjected to an etching process, a baking process, etc. after application, and ink is applied to the bank surface in the next process, so that it has resistance to organic solvents, It is desirable to use a material that does not easily cause alteration.

For example, a photosensitive resist containing a fluororesin such as a fluorinated polyolefin resin, a fluorinated polyimide resin, or a fluorinated polyacrylic resin can be used. Specific examples of the fluororesin include a fluorine-containing polymer described in JP-T-2002-543469; LUMIFLON (registered trademark, Asahi Glass) which is a copolymer of fluoroethylene and vinyl ether.

As shown in FIG. 2C, a photomask having an opening corresponding to the bank formation scheduled region is overlaid on the bank material layer 5a. Then, when UV exposure is performed, only the portion of the bank material layer 5a irradiated with UV light is polymerized and cured.

Then, when developed as shown in FIG. 2D, the bank material layer 5a is patterned into a bank shape because the uncured portion is removed and the cured portion remains.

Further, by performing baking (heat treatment), a forward-tapered bank 5 is formed as shown in FIG.

As shown in FIG. 1G, a recess is formed between the banks 5, and the hole injection layer 4 is exposed on the bottom surface of the recess.

In the development and baking processes described above, the uncured portion of the bank material layer 5a is basically removed, but usually a portion of the bank material layer 5a remains on the bottom surface of the recess as a residue 5c. The next UV cleaning step is performed.

UV cleaning process:
Ultraviolet light having a vibration energy of light in the range of 458 to 472 kJ / mol is irradiated from the substrate on which the bank 5 is formed. For example, a low-pressure mercury lamp having a main radiation intensity at a main wavelength of 254 nm is used. A wavelength of 254 nm corresponds to vibration energy of 472 kJ / mol.

The illuminance when the substrate is irradiated with UV light is preferably set in the range of 5 to 150 mW / cm ² .

The irradiation time is set so that the total amount of UV light to be irradiated (integrated light amount) is 690 to 1035 mJ / cm ² . This integrated light quantity is represented by the product of illuminance and irradiation time (integrated light quantity = illuminance x irradiation time).

As described above, when the illuminance is 5 to 150 mW / cm ² and the integrated light quantity is set to 690 to 1035 mJ / cm ² , the irradiation time is at least 690/150 = 4.6 (seconds), and the longest is 1035/5 = 207. (Seconds). Therefore, the irradiation time is set within a range of about 5 to 200 seconds.

The details of the UV cleaning process will be described later.

Hole transport layer formation process:
The hole transport layer 6 is formed as shown in FIG. 3A by filling the recesses between the banks 5 with ink containing the material of the hole transport layer and drying.

Examples of the material for the hole transport layer 6 include poly (3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid (PEDOT-PSS) and derivatives thereof (such as copolymers). The thickness of the hole transport layer 6 is usually 10 nm or more and 100 nm or less, for example, 20 nm.

Light emitting layer forming process:
The recesses between the banks 5 are filled with ink containing an organic light emitting material. That is, ink is printed by a droplet discharge method (inkjet method) between the plurality of banks 5 over the entire substrate 1. As a method for filling the ink between the banks, a dispenser method, a nozzle coating method, a spin coating method, intaglio printing, letterpress printing, or the like may be used.

Then, the filled ink is dried under reduced pressure and baked to form the light emitting layer 7 as shown in FIG. The thickness of the light emitting layer 7 is 60 to 90 nm.

Examples of organic light-emitting materials include, for example, oxinoid compounds, perylene compounds, coumarin compounds, azacoumarin compounds, oxazole compounds, oxadiazole compounds, perinone compounds, pyrrolopyrrole compounds, naphthalene compounds, anthracene compounds described in JP-A-5-163488 , Fluorene compounds, fluoranthene compounds, tetracene compounds, pyrene compounds, coronene compounds, quinolone compounds and azaquinolone compounds, pyrazoline derivatives and pyrazolone derivatives, rhodamine compounds, chrysene compounds, phenanthrene compounds, cyclopentadiene compounds, stilbene compounds, diphenylquinone compounds, styryl compounds , Butadiene compound, dicyanomethylenepyran compound, dicyanomethylenethiopyran compound, fluorescein compound , Pyrylium compounds, thiapyrylium compounds, serenapyrylium compounds, telluropyrylium compounds, aromatic aldadiene compounds, oligophenylene compounds, thioxanthene compounds, anthracene compounds, cyanine compounds, acridine compounds, metal complexes of 8-hydroxyquinoline compounds, 2-bipyridine compounds Metal complexes, Schiff salts and group III metal chains, oxine metal complexes, rare earth complexes, and the like.

The ink is manufactured by dissolving the organic light emitting material constituting the light emitting layer 7 as a solute and dissolving it in a solvent containing a solvent having a relatively high boiling point (boiling point: 170 to 300 ° C.).

Examples of the high boiling point solvent include cyclohexylbenzene, diethylbenzene, decahydronaphthalene, methylbenzoate, acetophenone, phenylbenzene, benzyl alcohol, tetrahydronaphthalene, isophorone, n-dodecane, dicyclohexyl, and p-xylene glycol dimethyl ether. These solvents may be used alone, or may be a mixture of a plurality of solvents, or a mixture of the above high boiling point solvent and a low boiling point solvent.

Electron injection layer, upper electrode, sealing layer formation process:
As shown in FIGS. 3C to 3E, an electron transport layer 8, a cathode electrode 9 as an upper electrode, and a sealing layer 10 are sequentially formed so as to cover the bank 5 and the light emitting layer 7.

The electron transport layer 8, the cathode electrode 9, and the sealing layer 10 are formed so as to be continuous with the pixel planned region of the adjacent organic EL element beyond the pixel planned region defined by each bank 5.

The electron transport layer 8 is formed by, for example, ETL vapor deposition (thickness 20 nm) using barium, lithium fluoride, or a combination thereof. The electron transport layer 8 has a function of transporting electrons injected from the cathode electrode 9 to the light emitting layer 7.

The cathode electrode 9 is formed by plasma deposition of a light transmissive material, for example, ITO, IZO (indium zinc oxide) or the like (thickness: 100 nm).

The sealing layer 10 is formed of a material such as SiN (silicon nitride) or SiON (silicon oxynitride) by CVD (thickness: 1 μm). The sealing layer 10 has a role of suppressing the light emitting layer 7 and the like from being exposed to moisture or being exposed to air.

Thus, an organic EL display panel in which top emission type organic EL elements are arranged in a matrix is manufactured.

The following steps shown in FIG. 4 are performed on the panel thus manufactured.

In the bonding step, the color filter substrate is bonded to the panel produced as described above via a sealing material.

In the scribe and break process, the panel is divided into a predetermined size.

In the mounting process, the drive circuit is mounted.

Thus, an organic light emitting display device is manufactured.

<Details and effects of UV cleaning process>
Since the vibration energy (458 to 472 kJ / mol) of the UV light is larger than the maximum value of the C—H bond energy of the resin component, basically, the C—H bond of the resin component is dissociated by the UV light irradiation. However, since it is smaller than the minimum value of the C—F bond energy of the fluorine component, the C—F bond is not dissociated by the UV light irradiation.

Therefore, (1) while ensuring the liquid repellency of the bank surface, (2) the area occupied by the bank residue on the hole injection layer 4 can be reduced.

(1) By ensuring the liquid repellency of the bank surface, when the ink of the hole transport layer 6 and the light emitting layer 7 is printed between the banks 5, the ink filled between the banks 5 is outside the banks 5. Good printability can be obtained without flowing out.

(2) Since the area occupied by the bank residue on the hole injection layer 4 is reduced, the hole injection property in the device is improved.

This point will be described with reference to FIG.

FIG. 4 is a chart showing the binding energy of various molecules and the vibration energy (kJ / mol) of light of various lamps.

As shown in FIG. 4, the CF bond dissociation energy in fluorobenzene is 524 kJ / mol, and the CF bond energy in fluoromethane is 472 kJ / mol, whereas the UV light (254 nm) of a low-pressure mercury lamp. Is less than or equal to the C—F bond energy because its vibrational energy is 472 kJ / mol. Therefore, the C—F bond is not dissociated by the vibrational energy of the UV light (254 nm).

On the other hand, FIG. 4 shows methyl group, CH bond energy (457 kJ / mol, 432 kJ / mol) of methane, etc. Generally, when the bond energy of CH bond in the resin component is close to this value, As can be seen, the vibration energy (458 to 472 kJ / mol) of the UV light is larger than the bond energy of the CH bond in a general resin component. Therefore, irradiation with UV light having vibration energy of 458 to 472 kJ / mol can dissociate the C—H bond and decompose the resin component.

FIG. 6 schematically shows a state in which when the UV light (wavelength 254 nm) is irradiated from above the bank, the residue and the CH bond on the bank surface are dissociated and the CF bond remains without dissociation. FIG.

Further, in the UV cleaning process of the present embodiment, as described above, the total sum of UV light (integrated light amount) is also set within the range of 690 to 1035 mJ / cm ² .

Therefore, according to the manufacturing method of the present embodiment, the resin component in the residue is decomposed while reliably suppressing the decomposition of the fluorine component present on the surface of the bank 5 and ensuring the liquid repellency of the surface of the bank 5. The area occupied by the bank residue on the hole injection layer 4 can be reduced.

<Experiment>
Experiment 1: Residual amount of fluorine A bank was formed on a substrate by spin-coating a bank material on a flat glass and patterning it with a photolithographic technique. Here, it was formed on a substrate (a bank having a width of 30 μm with a gap of 60 μm).

When performing the UV cleaning process on the substrate on which the bank is formed, the illuminance for irradiating the UV light (wavelength 254 nm) from above the bank is constant at 23 mW / cm ² , and the irradiation time of the UV light is 0 seconds, 10 It was examined how the residual amount of fluorine on the surface of the hole injection layer 4 was changed by changing the seconds, 30 seconds, and 60 seconds.

As the bank material, a copolymer of fluoroethylene and vinyl ether was used.

The measurement of the residual amount of fluorine was performed by measuring the negative ion intensity on the surface of the hole injection layer 4 under the following analysis conditions using a time-of-flight secondary ion mass spectrometry (TOF-SIMS) method.

Irradiated ion Ga +
Primary ion energy (Negative) 18 keV
Ion irradiation area (Negative) 30 × 30μm
Analysis / Analysis Area (Negative) 15 × 30μm
FIG. 7 is a graph showing the measurement results, in which the negative ionic strength measurement value before UV irradiation is normalized as the reference value 10. Rf is a measured value when the bank 5 is not formed on the hole injection layer 4.

From the results shown in FIG. 7, when UV light (wavelength 254 nm) is irradiated for 10 seconds to 60 seconds (integrated light amount 230 m to 1380 J / cm ² ), the normalized ion intensity is 3.0 × 10 ⁰ to 1 It is within the range of ^0.0 × 10 ⁰ and is smaller in the range of 0.3 or more and less than 1 compared with the normalized fluorine ion intensity (1.0 × 10 ¹ ) before irradiation (0 second). However, it can be seen that about 100 times as much fluorine remains as compared with Rf.

This is because, when UV light (wavelength 254 nm) is irradiated with an integrated light amount of 230 mJ / cm ² or more, the fluorine component is decomposed to some extent, but when the integrated light amount is 1380 mJ / cm ² or less, a large amount of fluorine component remains. Show.

Experiment 2: Ink contact angle In the UV cleaning process, the illuminance for irradiating UV light between banks is constant at 23 mW / cm ² , and the irradiation time is changed to 0 seconds, 30 seconds, 45 seconds, and 60 seconds to change the bank surface. Then, a drop of ink for forming a light emitting layer of the organic EL element was dropped, and the contact angle of the ink with respect to the bank surface was measured.

The ink used was butyl benzoate as solvent, polyfluorene polymer (product name: Poly (9,9-di-n-dodecylfluorenyl-2,7-diyl), manufactured by Aldrich), and the concentration was 1.0 wt% It is.

FIG. 8 is a diagram and a table showing the results.

As shown in FIG. 8, the contact angle is 45 ° in the initial stage (0 seconds), the contact angle gradually decreases as the irradiation time elapses, and the contact angle decreases to 35 ° when 45 seconds elapse. Yes. The accumulated light quantity after 45 seconds is 45 × 23 = 1035 mJ / cm ² .

Incidentally, the printability of the ink is good when the contact angle of the ink with respect to the bank surface is 35 ° or more. That is, if the contact angle is in the range of 35 ° or more and 60 ° or less, the ink is unlikely to overflow from between the banks when the ink is filled in the openings between the banks as shown in FIG. 6C. Experience has shown that the light emitting layer 7 can be satisfactorily formed over the entire panel.

Therefore, by setting the integrated light amount when irradiating the banks with UV light to 1035 mJ / cm ² or less, the contact angle of the ink with respect to the banks is maintained at 35 ° or more, and ink can be printed favorably between the banks (inkjet It can be filled with.

The contact angle of the ink with respect to the bank surface varies somewhat depending on the type of the bank material used and the solvent of the ink, but if a bank material and an ink solvent containing a fluorine component and a resin component that are generally used in an organic EL element are used. It is considered that a result almost similar to the result shown in FIGS.

Experiment 3: VJ characteristics Based on the above embodiment, the second anode electrode 3 (ITO layer, thickness 100 nm), the hole injection layer 4 (WOx layer, thickness 30 nm), and the bank 5 are formed on the substrate. Then, after irradiating UV light (wavelength 254 nm) at an illuminance of 23 mW / cm ² for 0 seconds, 30 seconds, and 45 seconds, the ink is applied between the banks and dried, the hole transport layer 6 (thickness 30 nm), A light emitting layer 7 (thickness 95 nm) is formed, and an electron transport layer 8 (Ba layer, thickness 5 nm) and a cathode electrode 9 (Al layer, thickness 120 nm) are formed in this order to form a device sample for testing. did.

And about each produced element sample, luminous efficiency ((eta)) was measured changing current density (J).

FIG. 9 is a graph of J-η characteristics showing the result.

As shown in FIG. 9, when the irradiation time of the UV light is 30 seconds and 45 seconds (integrated light amount is 690 to 1035 mJ / cm ² ), the light emission is larger than that when the UV light is not irradiated (0 seconds). Efficiency improved by about 40%.

Moreover, the relationship between the drive voltage (V) and the current density (J) was also measured for each of the fabricated element samples.

FIG. 10 is a graph of VJ characteristics showing the result.

As can be seen from FIG. 10, when the UV light irradiation time is 30 seconds and 45 seconds, the drive voltage required to obtain the same current density is higher than that when the UV light is not irradiated (0 seconds). It is low. The degree of decrease in the drive voltage is about ² V at a current density of 10 mA / cm ² .

Experiment 4: Lifetime characteristics A constant driving voltage such that the initial luminance is 8000 cd / m ² for an element sample irradiated with UV light (wavelength 254 nm) at an illuminance of 23 mW / cm ² for 30 seconds and an element sample not irradiated with UV light. The luminance when driven by was measured over time.

FIG. 11 is a graph showing the results. It can be seen that the element sample irradiated with UV light has less decrease in luminance over time.

In addition, an element sample irradiated with UV light (wavelength 254 nm) at an illuminance of 23 mW / cm ² for 30 seconds and an element sample not irradiated with UV were driven at a constant luminance of 8000 cd / m ² , and the drive voltage was changed over time. It was measured. FIG. 12 is a graph showing the results.

As shown in FIG. 12, it can be seen that the element sample irradiated with UV light has a smaller initial driving voltage and a smaller increase in driving voltage over time than the element sample not irradiated with UV light.

<Modification>
Although the embodiment has been described above, the following modifications can be considered.

(1) In the above embodiment, the light emission color of the light emitting layer in the organic EL display is not mentioned, but the present invention can be applied not only to a single color display but also to a full color display organic EL display. In an organic EL display of full color display, the organic EL element corresponds to a subpixel of each RGB color, and adjacent RGB subpixels are combined to form one pixel, and this pixel is arranged in a matrix to form an image display area Is formed.

(2) In the above embodiment, the top emission type organic EL display has been described as an example. However, the present invention can be similarly applied to the case where the light emitting layer of the bottom emission type organic EL display is formed.
(3) The present invention can also be applied to an organic TFT (Thin Film Transistor).

The present invention is effective for manufacturing an organic EL panel such as an organic EL display as well as an organic EL light source by a method of forming a light emitting layer by a wet method.

In the organic EL display, the light emission characteristics are good and uniform light emission characteristics can be obtained in the image display surface, which contributes to the improvement of the image quality.

DESCRIPTION OF SYMBOLS 1 TFT substrate 1a Planarization film 2 1st anode electrode 3 2nd anode electrode 4 Hole injection layer 5 Bank 5a Bank material layer 5c Residue 6 Hole transport layer 7 Light emitting layer 8 Electron transport layer 9 Cathode electrode 10 Sealing layer

Claims

A first step of preparing a substrate;
A second step of forming a functional layer including a lower electrode above the substrate;
A photosensitive resist material containing a fluorine component and a resin component is applied above the functional layer, and a part of the photosensitive resist material is exposed and patterned to form an opening corresponding to the pixel portion. A third step of forming a bank that partitions adjacent pixel portions;
A fourth step of irradiating the opening and the bank with ultraviolet rays;
After the fourth step, a fifth step of forming an organic light emitting layer by applying an ink containing an organic light emitting material to the opening and drying it;
A sixth step of forming an upper electrode above the organic light emitting layer;
Have
In the fourth step, irradiation is performed using ultraviolet light having a vibration energy of light in the range of 458 to 472 kJ / mol, so that the total amount of light to be irradiated (integrated light amount) is 690 to 1035 mJ / cm 2. A method for manufacturing an organic light emitting device.
The vibration energy of the light is
2. The method of manufacturing an organic light emitting element according to claim 1, wherein the organic light emitting element has a value larger than the dissociation energy of the resin component and smaller than the dissociation energy of the fluorine component.
The integrated light quantity in the fourth step is represented by the product of illuminance and irradiation time,
The illuminance is in the range of 5 to 150 mW / cm 2 ;
2. The method of manufacturing an organic light-emitting element according to claim 1, wherein the irradiation time is in the range of 5 to 200 seconds.
In the second step, a hole injection layer (HIL) containing tungsten oxide (WOx) is used as a functional layer,
The normalized ionic strength (value normalized based on the tungsten oxide component) of the fluorine component on the functional layer after the fourth step is 3.0 × 10 0 or more and 1.0 × 10 1 or less. The manufacturing method of the organic light emitting element of Claim 1.
The normalized ionic strength of the fluorine component on the functional layer after the fourth step is 0.3 or more relative to the normalized ionic strength of the fluorine component on the functional layer after the third step. The method for producing an organic light emitting device according to claim 1, wherein the organic light emitting device is less than 1.
2. The method of manufacturing an organic light-emitting element according to claim 1, wherein the contact angle of the ink containing the organic light-emitting material with respect to the bank after being irradiated with ultraviolet rays in the fourth step is 35 ° to 60 °. .
The functional layer includes a hole injection layer,
The resin component attached to the surface of the hole injection layer from the bank in the third step is removed by irradiating the opening with ultraviolet rays in the fourth step. 2. A method for producing an organic light emitting device according to 1.
An organic light emitting device manufactured by the manufacturing method according to any one of claims 1 to 7,
An organic light emitting display device having a drive circuit for driving the organic light emitting element.
A first step of preparing a substrate;
A second step of forming a functional layer including a lower electrode above the substrate;
A photosensitive resist material containing a fluorine component and a resin component is applied above the functional layer, and the photosensitive resist material is exposed and patterned to form openings corresponding to the pixel portions and adjacent to each other. A third step of forming a bank for partitioning the pixel portion;
A fourth step of irradiating the opening and the bank with ultraviolet rays;
After the fourth step, a fifth step of forming an organic light emitting layer by applying an ink containing an organic light emitting material to the opening and drying it;
A sixth step of forming an upper electrode above the organic light emitting layer;
In the fourth step, the vibration energy of the ultraviolet light is larger than the dissociation energy of the resin material used, and smaller than the dissociation energy of the fluorine component used.
Further, the total amount of light to be irradiated (integrated light amount) is such that the normalized ionic strength of the fluorine component on the functional layer after the fourth step is the normalized ionic strength of the fluorine component on the functional layer after the third step. On the other hand, the value of the ratio is 0.3 or more and less than 1, The manufacturing method of the organic light emitting element characterized by the above-mentioned.
The dissociation energy of the resin material is 335 to 457 kJ / mol, the dissociation energy of the fluorine component is 472 to 524 kJ / mol, and the vibration energy of the ultraviolet light is 458 to 472 kJ / mol,
10. The method of manufacturing an organic light emitting device according to claim 9, wherein the integrated light quantity is 690 to 1035 mJ / cm 2 .