WO2014038559A1 - 有機電界発光素子及びその製造方法 - Google Patents
有機電界発光素子及びその製造方法 Download PDFInfo
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- WO2014038559A1 WO2014038559A1 PCT/JP2013/073712 JP2013073712W WO2014038559A1 WO 2014038559 A1 WO2014038559 A1 WO 2014038559A1 JP 2013073712 W JP2013073712 W JP 2013073712W WO 2014038559 A1 WO2014038559 A1 WO 2014038559A1
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- H—ELECTRICITY
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- H10K77/00—Constructional details of devices covered by this subclass and not covered by groups H10K10/80, H10K30/80, H10K50/80 or H10K59/80
- H10K77/10—Substrates, e.g. flexible substrates
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
- C03C17/38—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal at least one coating being a coating of an organic material
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- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/14—Carrier transporting layers
- H10K50/15—Hole transporting layers
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- H—ELECTRICITY
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/14—Carrier transporting layers
- H10K50/16—Electron transporting layers
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- H10K50/17—Carrier injection layers
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- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/17—Carrier injection layers
- H10K50/171—Electron injection layers
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- H—ELECTRICITY
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
- H10K71/10—Deposition of organic active material
- H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
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- H10K2102/00—Constructional details relating to the organic devices covered by this subclass
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K2102/00—Constructional details relating to the organic devices covered by this subclass
- H10K2102/301—Details of OLEDs
- H10K2102/341—Short-circuit prevention
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K2102/00—Constructional details relating to the organic devices covered by this subclass
- H10K2102/301—Details of OLEDs
- H10K2102/351—Thickness
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/60—Organic compounds having low molecular weight
- H10K85/615—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
- H10K85/626—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene containing more than one polycyclic condensed aromatic rings, e.g. bis-anthracene
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- H—ELECTRICITY
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/60—Organic compounds having low molecular weight
- H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
- H10K85/633—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/549—Organic PV cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to an organic electroluminescent device and a method for producing the same.
- organic electroluminescent elements can emit light in various colors with a simple element configuration, they have been actively developed in recent years as technologies for manufacturing light emitting devices such as displays and illumination.
- An organic electroluminescent element is an element that emits light by injecting positive and negative charges (carriers) into an organic layer between electrodes and recombining the carriers.
- a glass base material As a base material of an organic electroluminescent element, a glass base material has been widely used from the viewpoints of light transmittance, flatness, rigidity, and the like.
- soda lime glass hereinafter sometimes referred to as alkali glass
- a float method As a material and a manufacturing method of a glass substrate, soda lime glass (hereinafter sometimes referred to as alkali glass) by a float method is generally used because a glass substrate having a large area can be easily obtained at low cost.
- alkali glass soda lime glass
- it is common to use alkali-free glass by a fusion method. The reason is as follows.
- Soda lime glass is a glass containing a large amount of alkali components.
- alkali metal is eluted and diffused into the organic electroluminescent device on the base material due to changes over time. This tends to cause deterioration of the device and reduce the lifetime of the organic electroluminescent device. Therefore, as the material of the glass substrate for the organic electroluminescent element, alkali-free glass containing almost no alkali component is suitably used (see Patent Document 1).
- the float method melts the glass material uniformly in the melting furnace, continuously pours the glass out of the outlet, and slowly slides it over the pool furnace where the tin is melted. It is a method of taking out.
- the float method is easier to produce a plate glass having a larger area than the fusion method, and can produce a plate glass at a lower cost.
- the float method has a problem that the flatness is poor and there are many surface defects as compared with the fusion method. If there are many surface defects on the glass substrate, micro defects will occur in the organic electroluminescent device, which may cause electrical device defects such as local shorts and leaks.
- alkali-eluted glass produced by the fusion method is preferably used because the elements are less deteriorated by alkali elution, have good flatness, and have few surface defects. It is thought that However, alkali-free glass has a higher manufacturing cost because alkali metals, which are impurities, are reduced compared to soda-lime glass, and the fusion method also has a lower manufacturing cost than the float method. There is a problem that it is expensive.
- Patent Document 1 For the purpose of producing an organic electroluminescent device at a lower cost, in Patent Document 1, alkali glass is used as a base material, and a barrier layer made of SiO 2 is provided on the surface of the base material to elute alkali into the organic electroluminescent device.
- the manufacturing method is a float method, and the problem of surface defects is considered insufficient.
- an attempt has been made to use a glass substrate produced by a cheaper float method for an organic electroluminescent element, but in that case, the surface of the substrate is polished in order to improve the surface property of the glass substrate. There is a problem that the manufacturing cost becomes high (see Patent Document 3).
- Patent Document 3 states that “a soda-lime glass substrate for STN-LCD needs to reduce the waviness of the glass substrate for the purpose of suppressing cell gap unevenness. Therefore, the glass surface is polished. However, in order to use it for the application of a passive organic EL element, it is necessary to control the unevenness of a finer glass substrate. ”Since the glass substrate described in Patent Document 3 is described, It is thought that the swell was reduced. Moreover, in the Example of patent document 3, each layer is formed on the anode by the vacuum evaporation method.
- An object of the present invention is to provide an organic electroluminescence device that can be produced at low cost with few electrical device defects such as short-circuiting or leakage when an organic electroluminescence device is produced. Furthermore, even when an organic electroluminescent device is produced using a non-polished glass substrate manufactured by the float process, an organic electroluminescent device that can be produced at low cost with few electrical device defects such as shorts or leaks is provided. The purpose is to do.
- the inventors of the present invention include a cross-linked aromatic amine polymer and a specific film thickness, as a result of the charge injection and transport layer forming the organic electroluminescent element, The inventors have found that the above object can be achieved and have reached the present invention.
- the glass base material is an unpolished glass base material produced by a float process and has a specific swell shape
- the glass base material is an unpolished glass base material produced by a float process and has a specific swell shape
- the glass base material The present inventors have found that an organic electroluminescent device having a charge injecting and transporting layer containing a specific aromatic amine polymer in a specific film thickness achieves the above object, and has reached the present invention.
- the first invention of the present application is An organic electroluminescent device in which at least a first conductive layer, a charge injecting and transporting layer, a light emitting layer, and a second conductive layer are laminated on a glass substrate, (1)
- the minimum value of the undulation tangent of the surface of the glass substrate on the first conductive layer side is 4.00 ⁇ 10 ⁇ 6 or more, or the maximum value of the undulation tangent is 22 ⁇ 10 ⁇ 6 or more
- the charge injection transport layer is a layer formed by a wet film formation method, (3)
- the charge injection transport layer includes a charge injection layer in contact with the first conductive layer, (4)
- the charge injection transport layer has a thickness of 130 to 1000 nm, (5)
- the charge injection layer includes a crosslinked aromatic amine polymer, Organic electroluminescent device.
- the density of the surface defect in the state which formed the said 1st conductive layer on the said glass base material is 2.0 piece / cm ⁇ 2 > or more.
- the glass substrate preferably contains at least one of Na 2 O and K 2 O more than 1.0 wt%.
- the charge injecting and transporting layer preferably has a thickness of 130 to 500 nm.
- the glass substrate is preferably manufactured by a float process, and more preferably an unpolished glass substrate.
- the crosslinked aromatic amine polymer preferably includes a partial structure represented by the following formula (1).
- the crosslinked aromatic amine polymer preferably has a crosslinked structure derived from a crosslinkable group selected from the following crosslinkable group group T. ⁇ Crosslinkable group T>
- R 21 to R 25 each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.
- Ar 41 represents an aromatic hydrocarbon group or substituent which may have a substituent.
- the present inventors have found that an organic electroluminescent element having a specific thickness of a charge injecting and transporting layer containing a specific aromatic amine polymer on the substrate achieves the above object, and has reached the present invention.
- the second invention of the present application is An organic electroluminescent device in which at least a first conductive layer, a charge injecting and transporting layer, a light emitting layer, and a second conductive layer are laminated on a substrate, (1)
- the charge injection transport layer is a layer formed by a wet film formation method, (2)
- the charge injection transport layer includes a charge injection layer in contact with the first conductive layer, (3)
- the charge injection transport layer has a thickness of 130 to 1000 nm, (4)
- the charge injection layer includes a crosslinked aromatic amine polymer, Organic electroluminescent device.
- the said base material is a glass base material
- the density of the surface defect in the state which formed the said 1st conductive layer on this glass base material is 2.0 piece / cm ⁇ 2 > or more. Is preferred.
- the said glass base material is manufactured by the float glass process, and it is more preferable that the said glass base material is an unpolished glass base material.
- the charge injecting and transporting layer preferably has a thickness of 130 to 500 nm.
- the third invention of the present application corresponds to the method of manufacturing the organic electroluminescent element of the first invention,
- a glass substrate in which the minimum value of the undulation tangent of the surface of the one conductive layer is 4.00 ⁇ 10 ⁇ 6 or more, or the maximum value of the undulation tangent is 22 ⁇ 10 ⁇ 6 or more.
- the charge injection transport layer is formed by a wet film formation method, (3)
- the charge injection transport layer includes a charge injection layer in contact with the first conductive layer, (4)
- the charge injection layer is formed by applying, drying, and crosslinking a composition containing an aromatic amine polymer having a crosslinkable group and a solvent by a wet film formation method, (5) forming the charge injecting and transporting layer with a thickness of 130 to 1000 nm;
- the present invention relates to a method for manufacturing an organic electroluminescent device.
- the density of the surface defect in the state which formed the said 1st conductive layer on the said glass base material is 2.0 piece / cm ⁇ 2 > or more.
- the glass substrate it is preferable to use a glass substrate containing at least one of 1.0 mass% of Na 2 O and K 2 O.
- the charge injecting and transporting layer preferably has a thickness of 130 to 500 nm.
- the glass substrate it is preferable to use a glass substrate manufactured by a float method, and it is more preferable to use an unpolished glass substrate manufactured by a float method. preferable.
- the fourth invention of the present application corresponds to the method for producing an organic electroluminescent element of the second invention
- a method for producing an organic electroluminescent device in which at least a first conductive layer, a charge injecting and transporting layer, a light emitting layer, and a second conductive layer are laminated on a substrate (1)
- the charge injection transport layer is formed by a wet film formation method
- the charge injection transport layer includes a charge injection layer in contact with the first conductive layer
- the thickness of the charge injecting and transporting layer is 130 to 1000 nm
- the charge injection layer is formed by applying, drying, and crosslinking a composition containing an aromatic amine polymer having a crosslinkable group and a solvent by a wet film formation method.
- the present invention relates to a method for manufacturing an organic electroluminescent device. 4th this invention WHEREIN:
- the said base material is a glass base material, and the density of the surface defect in the state which formed the said 1st conductive layer on this glass base material is 2.0 piece / cm ⁇ 2 > or more. Is preferred.
- the glass substrate it is preferable to use a glass substrate manufactured by a float method, and it is more preferable to use an unpolished glass substrate manufactured by a float method.
- the charge injecting and transporting layer preferably has a thickness of 130 to 500 nm.
- the inventors of the present invention achieved the above object by using an organic electroluminescence device having a charge injection / transport layer having a specific film thickness ratio with respect to the first conductive layer on an unpolished glass substrate manufactured by a float process.
- the present invention has been found.
- the fifth invention of the present application is Organic electroluminescence having, in this order, at least a first conductive layer, a charge injection transport layer containing a charge transport material, a light emitting layer, and a second conductive layer formed on a glass substrate by a wet film formation method
- An element The glass substrate is produced by a float process, The glass substrate surface on the first conductive layer forming side is in an unpolished state,
- the thickness of the charge injecting and transporting layer is 1.3 times or more of the thickness of the first conductive layer.
- the present inventors have found that the non-polished glass substrate produced by the float process has a specific undulation shape, and the glass substrate having the specific undulation shape is specific to the first conductive layer. It has been found that an organic electroluminescent device having a charge injection / transport layer with a film thickness ratio achieves the above object, and has reached the present invention.
- the sixth invention of the present application is Organic electroluminescence having, in this order, at least a first conductive layer, a charge injection transport layer containing a charge transport material, a light emitting layer, and a second conductive layer formed on a glass substrate by a wet film formation method
- An element The minimum value of the undulation tangent of the surface of the glass substrate on the first conductive layer forming side is 4.20 ⁇ 10 ⁇ 6 or more, or the maximum value of the undulation tangent is 22 ⁇ 10 ⁇ 6 or more
- the thickness of the charge injecting and transporting layer is 1.3 times or more of the thickness of the first conductive layer.
- the charge injection layer in contact with the first conductive layer in the organic electroluminescent element contains a specific polymer and the film thickness is in a specific range, an electrical element defect such as short circuit or leakage occurs. It is possible to obtain an organic electroluminescent element with a small amount. Furthermore, even when the substrate is a glass substrate, the first conductive layer side surface of the glass substrate has a specific waviness tangent value, and an unpolished glass substrate manufactured by the float process is used, It is possible to obtain an organic electroluminescence device with few electrical device defects such as short circuit or leakage.
- FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an organic electroluminescent element of the present invention.
- the substrate supporting the organic electroluminescent element is expressed as “substrate” when instructing including the first conductive layer, and “base material” when indicating without including the first conductive layer. . When both are instructed together, they are called “base material”.
- the main material of the support is specifically indicated, the material is displayed immediately before each term. For example, when the main material is glass, they are “glass substrate”, “glass substrate”, “glass substrate and the like”.
- the present invention relates to an organic electroluminescent device comprising an aromatic amine polymer having a cross-linked charge injecting and transporting layer and having a specific film thickness capable of reducing electrical element defects such as short circuit or leakage. It is characterized by realization. Furthermore, an organic electroluminescent element having good characteristics has been realized by using a low-cost glass substrate that has been extremely difficult to use in order to maintain the characteristics of the organic electroluminescent element. Specifically, it is characterized in that an organic electroluminescent element capable of reducing electrical element defects such as shorts or leaks is realized without polishing a glass substrate produced by a float process.
- the surface of the glass substrate on which the first conductive layer is formed on the glass substrate manufactured by the float process has poor flatness as described above, and there are many surface defects. Surface defects consist of fine irregularities on the glass substrate or fine peeling of the first conductive layer.
- the surface defect location In this case, since a desired layer configuration cannot be realized, a region that does not function as an organic electroluminescent element is generated when viewed microscopically, which adversely affects the overall characteristics.
- the charge injection / transport layer is formed immediately above the first conductive layer, a short circuit or a leak as an organic electroluminescence device is formed on the surface after the charge injection / transport layer is formed. It is considered that the surface defects that lead to the problem can be reduced.
- the charge injecting and transporting layer is formed by dry film formation such as sputtering or vacuum vapor deposition, it is easy to form a film following the defect shape on the first conductive layer. Is difficult to reduce.
- the charge injecting and transporting layer is formed by wet film formation such as spin coating or ink jetting, it is easy to form a flat surface regardless of the presence or absence of surface defects on the first conductive layer.
- the first aspect of the present invention is characterized in that the thickness of the charge injecting and transporting layer is 130 to 1000 nm.
- the thickness of the charge injecting and transporting layer is 130 to 1000 nm.
- the flatness of the glass substrate is poor and the flatness of the charge injecting and transporting layer is ensured even when there are many surface defects. Generation of a region that does not function as an element can be suppressed. Note that flatness can be ensured as the thickness increases, but the thickness is 1000 nm or less in order to suppress absorption of light emission from the light emitting material.
- the glass substrate manufactured by the float process has a feature that the flatness is lower than that of the glass substrate manufactured by the conventional fusion method, that is, the undulation of the substrate surface is large.
- the undulation on the surface of the glass substrate is as small as that of the glass substrate produced by the fusion method, but the undulation in the unpolished glass substrate of the present invention is Stays big. Therefore, the glass substrate or glass substrate used in the present invention has a feature of having a certain level of swell. Accordingly, in the first invention of the present application, as will be described in detail later, the waviness tangent of the surface of the glass substrate on the first conductive layer side has a specific value.
- the glass substrate produced by the fusion method naturally has few surface defects, but even if it is a glass substrate produced by the float process, the surface defects are eliminated by polishing. It can be reduced. Since the glass substrate of the present invention is not polished at all while being processed from a molten glass to a plate material, that is, in an “unpolished” or “no-polished” state, the glass substrate or glass substrate used in the present invention Is usually characterized by having a certain number of surface defects.
- the term “unpolished” is unified and the present invention is described in detail.
- the organic electroluminescent element of the present invention comprises at least a first conductive layer, a charge injection transport layer formed by a wet film forming method, a light emitting layer, and a second conductive layer on a substrate, preferably a glass substrate. And have a laminated structure.
- FIG. 1 is a schematic cross-sectional view showing an example of the structure of an organic electroluminescent device 10 of the present invention.
- FIG. 4 represents a hole transport layer formed by a wet film forming method
- 5 represents a light emitting layer
- 6 represents a hole blocking layer
- 7 represents an electron transport layer
- 8 represents an electron injection layer
- 9 represents a cathode.
- the first conductive layer of the present invention corresponds to the anode
- the charge injection / transport layer of the present invention is formed by the hole injection layer formed by the wet film formation method and the wet film formation method. It corresponds to a hole transport layer
- the second conductive layer of the present invention corresponds to a cathode.
- the organic electroluminescent device of the present invention includes a first conductive layer (anode), a charge injection / transport layer containing a charge transport material (a hole injection layer formed by a wet film formation method, and a positive electrode formed by a wet film formation method.
- the light emitting layer and the second conductive layer are essential constituent layers, but if necessary, other functional layers are provided between the essential layers as shown in FIG.
- the essential layer may have a multilayer structure of two or more layers.
- a hole transport layer formed by a vapor deposition method may be provided between the hole transport layer 4 and the light emitting layer 5 formed by a wet film formation method.
- the hole transport layer formed by the vapor deposition method does not correspond to the charge injection transport layer in the present application.
- the charge injection transport layer of the present invention is Only the injection layer 3 is considered.
- the substrate 1 serves as a support for the organic electroluminescent element.
- a base material of the organic electroluminescent element in the present invention a glass plate, a metal plate or a resin can be used. A light transmissive glass plate and a transparent resin sheet are preferable.
- the glass plate a glass substrate having a specific range of tangent tangent values, which has been difficult to use in the past, can be used (one of the features of the first invention of the present application). The following method is mentioned as a method for obtaining the glass base material which has the waviness tangent value of a specific range.
- the base material in this invention is a glass base material
- the glass base material 1 is manufactured by the float glass process.
- glass material such as SiO 2 is uniformly melted in a melting furnace, glass is continuously poured out from the outlet, and slowly slides on the pool furnace where tin is melted. It is a method of cooling and taking out.
- the glass substrate 1 of the present invention is manufactured by the float process, and has not been subjected to any mechanical or chemical polishing on the surface on which the first conductive layer or the like is formed. It is necessary to be in the state.
- the glass substrate by the fusion method can be used as the substrate of the organic electroluminescent element without being polished.
- the glass substrate manufactured by the float process is used as the substrate of the organic electroluminescent element.
- the glass substrate is held on the substrate holder using an Oscar-type single-side polishing machine, using a substrate holder with an opening hole that can accommodate the substrate in the upper pressure platen.
- polishing abrasive grains made of fine powders such as cerium oxide are dispersed in water and supplied as a slurry, while polishing by pressing one side against a polishing cloth adhered to a rotating lower polishing disk, Polishing by a so-called mechanical polishing method is widely performed (for example, see Japanese Patent Application Laid-Open No. 2004-276133). Furthermore, in the mechanical polishing method, the surface of the glass substrate may be scratched depending on the polishing conditions and the change in the condition of the polishing cloth. Therefore, chemical polishing for reducing such scratches may be used together (for example, (See Japanese Patent No. 4431516).
- the glass substrate that has undergone such a polishing step can remove surface defects and waviness caused by being produced by the float process, and can reduce the surface defects of the first conductive layer formed thereon, and further thereafter There was an effect of reducing element defects such as leaks and shorts generated in the organic electroluminescent element to be formed.
- the glass substrate that has been subjected to the polishing step is free from surface defects and waviness caused by being produced by the float process.
- “tangent” does not satisfy a specific value (details will be described later) defined in the first aspect of the present invention.
- the main component of the glass substrate 1 is SiO 2 and may contain a conventionally known impurity component as appropriate, but preferably an alkali containing at least one of Na 2 O and K 2 O in an amount of 1.0% by mass or more.
- the glass is more preferably alkali glass containing Na 2 O of 2.0% by mass or more, particularly preferably Na 2 O of 4.0% by mass or more.
- the upper limit of the total content of Na 2 O and K 2 O is usually 25.0% by mass, preferably 20.0% by mass.
- impurities other than Na 2 O and K 2 O include CaO, MgO, Al 2 O 3 , B 2 O 3 , P 2 O 5 , and ZrO 2 .
- the content of SiO 2 in the alkali glass is usually about 55% by mass to 80% by mass. Note that alkali glass is less expensive than alkali-free glass, and an organic electroluminescent device can be realized at lower cost.
- the components of the glass substrate are preferably determined using a composition analysis technique. For example, either semi-quantitative analysis or quantitative analysis can be adopted, but preferably a method based on quantitative analysis should be adopted in terms of accuracy.
- XRF X-ray fluorescence spectrometry
- GD-MS glow discharge mass spectrometry
- solid-state emission spectroscopy As a method of quantitative analysis, after the base material is decomposed with hydrofluoric acid or melted with alkali, atomic absorption analysis (AAS), inductively coupled plasma-Auger electron spectroscopy (ICP-AES), or the like is used. It is known that this is possible.
- AAS atomic absorption analysis
- ICP-AES inductively coupled plasma-Auger electron spectroscopy
- the glass substrate 1 of the present invention is manufactured by the float process, and the surface of the glass substrate on the first conductive layer forming side is unpolished. is there.
- a glass substrate produced by the float process tends to have a larger undulation on the surface of the glass substrate than a glass substrate produced by the fusion method.
- the waviness of the glass substrate surface falls also by grind
- the glass substrate of the present invention is one of the indicators of swell, and the minimum value of swell tangent was found to be 4.00 ⁇ 10 ⁇ 6 or more, or the maximum value of the waviness tangent was 22 ⁇ 10 ⁇ 6 or more. Further, the upper limit of the minimum value of the undulation tangent was 9.00 ⁇ 10 ⁇ 6 or less, and the upper limit of the maximum value of the undulation tangent was 100 ⁇ 10 ⁇ 6 or less.
- the minimum value of the waviness tangent is preferably 4.00 ⁇ 10 ⁇ 6 or more, more preferably 4.02 ⁇ 10 ⁇ 6 or more, and still more preferably 4.20 ⁇ 10 ⁇ 6 or more.
- the maximum value of the waviness tangent is usually 22 ⁇ 10 ⁇ 6 or more, preferably 28 ⁇ 10 ⁇ 6 or more, and more preferably 33 ⁇ 10 ⁇ 6 or more.
- it is preferable that the minimum value of the tangent tangent is equal to or greater than the above value, or the maximum value of the tangent tangent is equal to or greater than the above value. More preferably, the value is not less than the above value.
- the upper limit of the minimum value of the waviness tangent is usually 9.0 ⁇ 10 ⁇ 6 , preferably 8.5 ⁇ 10 ⁇ 6
- the upper limit of the maximum value of the waviness tangent is usually 100 ⁇ 10 ⁇ 6 , preferably 90 ⁇ 10 ⁇ 6 , more preferably 88 ⁇ 10 ⁇ 6 , still more preferably 70 ⁇ 10 ⁇ 6 , particularly preferably 60 ⁇ 10 ⁇ 6 , and most preferably 50 ⁇ 10 ⁇ 6 .
- the above preferred range is a standard undulation tangent of unpolished glass by the float method, and although it is an inexpensive glass, it can be controlled by controlling the components of the charge injection layer and the film thickness described later.
- the present invention is characterized by the size of the swell of the glass substrate or the glass substrate, but the glass substrate or the glass substrate itself was produced by commercially available glass or a known method. What is necessary is just to use what measures the wave
- the 1st conductive layer of a glass substrate is normally formed by vapor phase growth methods, such as sputtering method and a vacuum evaporation method, this layer is formed so that the surface property of a glass base material may be imitated substantially.
- the value of the wave tangent of the glass substrate in which the first conductive layer is formed on the glass substrate is almost the same as that of the glass substrate.
- the value of the undulation tangent of the first conductive layer surface may be different from the original value of the undulation tangent of the substrate surface. Waviness tangent should be evaluated.
- the definition and measurement method of the swell tangent are as follows.
- the definition relating to surface waviness basically uses “JIS B0601: 2001—Product Geometric Specification (GPS) —Surface Properties: Contour Curve Method—Terms, Definitions, and Surface Property Parameters”.
- the waviness is a surface property parameter calculated from the contents described in “3.1.7 Waviness profile”.
- a curve obtained by such data processing is particularly called a filtered undulation curve.
- the cut-off value and the contour curve filter are described in 2.6 (contour curve passband) and 3.2 (amplitude transfer characteristics) of JIS B0632.
- a specific method for measuring the swell tangent will be described.
- the surface of a glass substrate or the like is measured with a predetermined measuring device to obtain a measured cross-sectional curve.
- the length to be measured at this time that is, the evaluation length ln is not less than a reference length lw (equal to ⁇ f in the case of waviness), preferably not less than 3 times, more preferably not less than 5 times the reference length lw.
- the length should be set.
- the measurement data of the measurement sectional curve is digitized, and various subsequent data processing can be quickly executed by a computer or the like.
- the surface shape measuring device has the function, but it is a stylus type (mechanical, optical lever), optical type (white interference, laser interference, laser measurement).
- stylus type mechanical, optical lever
- optical type white interference, laser interference, laser measurement
- the above-mentioned “definition regarding swell” may be based on the old version of JIS B0601: '94, etc., instead of JIS B0601: 2001, but the correspondence with JIS B0601: 2001 If it is clear, it can be adopted as appropriate.
- a filtered waviness curve can be obtained by sequentially applying a contour curve filter having a wavelength cutoff value ⁇ f on the long wavelength side and a wavelength cutoff value ⁇ c on the short wavelength side to the obtained measurement sectional curve data.
- a contour curve filter having a wavelength cutoff value ⁇ f on the long wavelength side and a wavelength cutoff value ⁇ c on the short wavelength side
- ⁇ f 8.0 mm
- ⁇ c 0.8 mm
- Shape deviation curves Changes that should be distinguished from such waviness are collectively referred to as one of the contour curves called “shape deviation curves”, but must be carefully removed by the least squares method before applying the ⁇ f contour curve filter.
- the following parameters are defined as waviness property parameters from the thus obtained filtered waviness curve.
- Average line is a curve (see 3.2 of JIS B0632) representing a long wavelength component cut off by a low-pass (low pass) ⁇ f contour curve filter. Also referred to as the X axis.
- Extracted undulation contour curve element (curve portion consisting of a mountain and a valley adjacent to it) The definition of peaks and valleys is determined by how high or low they are from the average line. In general, the minimum height for judging peaks and valleys is a percentage of the maximum height (Wz) of the wavy contour curve. Regulate by. In this invention, if it is 10% or more of Wz, it will discriminate
- the waviness tangent and its minimum and maximum values are defined as follows.
- the waviness tangent is not limited to being calculated from a combination of values measured by one waviness contour curve element, and any method can be used as long as the measured values are obtained from the same sample. It can be obtained by calculating a value even in a possible combination.
- the glass substrate or glass substrate used in the present invention has a swell compared to a conventional glass substrate or the like as described above when a partition wall for partitioning an organic electroluminescent element such as an auxiliary electrode is provided. Since the contact area between the glass substrate or the like and the partition wall portion increases due to the large size, the effect of increasing the adhesion strength of the partition wall can be expected.
- SiO 2 having a film thickness of about 10 to 30 nm is used for the purpose of suppressing elution of alkali components from the glass substrate between the first substrate and the first conductive layer side surface of the glass substrate 1.
- a barrier layer may be provided.
- An anode or a cathode can be provided on the substrate as the first conductive layer.
- the charge injection / transport layer is a hole injection / transport layer
- the charge injection layer is a hole injection layer
- the second conductive layer is a cathode.
- the charge injection / transport layer is an electron injection / transport layer
- the charge injection layer is an electron injection layer
- the second conductive layer is an anode.
- the anode When providing an anode on a substrate, the anode is the first conductive layer in the present application.
- the anode 2 is an electrode that plays a role of hole injection into the layer on the light emitting layer 5 side.
- the anode 2 is required to have a certain electric conductivity in order to apply a sufficient voltage across the entire surface of the organic electroluminescent element.
- a certain level of transmittance is required since the light emitted from the organic electroluminescent element is usually taken out from the substrate side.
- This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, or platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, polyaniline, etc.
- a metal oxide such as an oxide of indium and / or tin (hereinafter, ITO) is used as the most preferred material.
- a thin conductive inorganic film may be formed on the surface of ITO or the like for the purpose of improving the hole injection property to the organic EL layer.
- a thin conductive inorganic film is also included in the first conductive layer.
- the thin conductive inorganic film include a light transmissive metal thin film or a light semi-transmissive metal thin film, or a metal oxide film such as molybdenum oxide or vanadium oxide.
- Formation of the anode 2 as the first conductive layer is appropriately performed by a known method such as a sputtering method, a vacuum deposition method, a coating method, or the like depending on the material used for the anode 2.
- a sputtering method is preferably used because of its ease of control of properties and characteristics.
- a sputtering method or a vapor deposition method is used for the thin conductive inorganic film, and a vapor deposition method is preferably used from the viewpoint of productivity and easy control of characteristics. What is necessary is just to select the thickness of the anode 2 suitably according to transparency, electrical conductivity, etc. which are required. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more. In this case, the thickness of the anode 2 is usually about 1000 nm or less, preferably about 500 nm or less.
- the glass substrate of the present invention has many surface defects.
- the surface defect on the glass substrate is a defect generated in the manufacturing process of the glass substrate, and is hereinafter referred to as “glass defect”.
- glass defects are classified into “glass internal defects” and “glass surface defects”, and each glass defect has various modes (categories classified according to the cause of occurrence, form, and mode).
- “inside glass defects” include impurities (inclusions) other than the glass material mixed in the molten glass, “internal bubbles” mixed in the molten glass, and the composition of the glass material segregates during cooling.
- Glass surface defects include “bubble-derived dents” that are not completely removed from the internal bubbles but are raised on the surface of the plate glass during cooling and become dents on the plate surface. Steam re-aggregates on the ceiling of the pool furnace and forms droplets that drop onto the glass plate being cooled and remain in contact with solids such as the “drip” (also referred to as top spec) and transport rolls in glass substrate manufacturing equipment There are scratches, etc. that can be made by etc.
- the reason for reducing or removing glass defects is that when the first conductive layer is formed on a glass substrate having many glass defects, the first conductive layer is not locally formed but becomes a pinhole, drip or scratch.
- an organic film such as a light emitting layer to be formed thereafter is locally thinned or not formed, and the first conductive layer and the second conductive layer are formed. This is because the distance between the two leads to a situation where the distance is close or in direct contact, and electrical characteristics lead to element defects such as short circuit or leakage.
- the surface defect of the glass substrate that leads to such an element defect occurs not only in the glass base material but also in the process of forming the first conductive layer. For example, scratches caused by contact with a solid such as a transport roll of a film forming facility may be mentioned.
- the first conductive layer is formed by sputtering using indium tin oxide (ITO), which is a transparent conductive material
- the film thickness is preferably in the range of about 500 nm or less as described above.
- the adhesion with the glass substrate is locally deteriorated due to adhesion of foreign matters in the thin film forming process, and the once formed ITO thin film is peeled off or further peeled off during the process.
- Protruding defects may occur when the film is reattached. Such a stripped portion or protrusion-like defect of the ITO thin film is very likely to lead to an electrical element defect such as a short circuit or a leak, like the glass defect generated in the state of the glass substrate.
- the density of these surface defects can be reduced by using a glass substrate prepared by the fusion method or by polishing the surface of the glass substrate prepared by the float method. In the glass substrate of the invention, the density of surface defects is higher than those of these glass substrates.
- the glass substrate As in the case of waviness, as a result of investigating the density of surface defects in the state where ITO is deposited to 110 nm or 150 nm on glass substrates of various glass manufacturers manufactured by the float method or the fusion method, It was found that the glass substrate usually has a surface defect density of 2.0 pieces / cm 2 or more. Moreover, the upper limit of the density of surface defects was preferably 16.0 pieces / cm 2 or less.
- the surface defect in the state where the first conductive layer is formed on the glass substrate of the present invention is defined as follows. That is, the surface defect of the present invention is a concave or convex shape abnormal portion with respect to the plane when the surface of the first conductive layer is a datum plane, and the planar size thereof has a major axis of 5 ⁇ m or more and 200 ⁇ m or less. Point to.
- the measurement of the density of the surface defects of the present invention is performed by measuring the presence frequency of the surface defects of the glass substrate using an optical microscope in a set measurement range and normalizing the measurement area.
- the magnification setting of an optical microscope and the proper use of bright-field, dark-field, and differential interference observation are often based on the experience of the measurer, but the appearance of surface defects using appropriately classified and set surface defect modes It is preferable to set and use properly so that can be accurately determined.
- the density of surface defects of the present invention the surface defects are observed and classified in advance for a large number of glass substrates, and after setting the mode of the surface defects, the glass substrate that requires measurement of the surface defects is 7 mm ⁇ 10
- the first conductive layer was patterned to a 5 mm square, and four surfaces of the first conductive layer were subjected to visual measurement using an optical microscope, normalized with the measurement area, the density of surface defects was calculated, and the average value was obtained.
- the surface defect of the minimum size is enlarged to about 1 mm in the eyepiece visual field.
- the observation mainly used bright field, and appropriately used dark field / differential interference observation. This use is for distinguishing deposits other than surface defects from surface defects.
- the hole injection transport layer is a charge injection transport layer in the present invention.
- a hole injection transport layer 11 containing a hole transport material is formed between the anode 2 and the light emitting layer 5 by a wet film forming method.
- the hole injecting and transporting layer 11 has a function of transporting holes injected from the anode 2 to the light emitting layer 5 and may be formed as a single layer. However, as shown in FIG. A two-layer structure of a hole injection layer 3 formed by a method and a hole transport layer 4 formed by a wet film formation method is preferable.
- the hole injection layer 3 is a charge injection layer in the present invention, and is in contact with the anode which is the first conductive layer in the present invention.
- the charge injection / transport layer contains an aromatic amine polymer, it is preferably a hole injection / transport layer.
- the reason why the hole injecting and transporting layer 11 is formed by the wet film forming method is as follows. In the state where the first conductive layer is formed on the base material of the present invention, the density of surface defects is large as described above, and if it remains as it is, there is a very high possibility of causing electrical element defects such as short circuits or leaks.
- the second conductive layer and the first conductive layer to be formed are in direct contact with each other or face each other through an extremely thin organic electroluminescent element material, and a voltage is generated between the first conductive layer and the second conductive layer.
- a short circuit if it was in direct contact, it was short-circuited, and if it was confronted through a very thin organic electroluminescent element material, it resulted in leakage. .
- the problem of covering various surface defects has been greatly solved. That is, because it is a wet film formation method, the organic electroluminescent element material is sufficiently wrapped around and covered on the uneven side surfaces of the surface defects, and the first conductive layer and the second conductive layer are in direct contact with each other. Alternatively, the situation of facing through an extremely thin organic electroluminescent element material becomes extremely difficult.
- the thickness of the charge injection transport layer provided in contact with the first conductive layer is 1.3 times or more the thickness of the first conductive layer (fourth and fifth inventions of the present application), or charge injection It has been found that if the film thickness of the transport layer is 130 to 1000 nm (first and second inventions of the present invention), the sufficient leakage reduction effect cannot be obtained unless this condition is satisfied. In the fourth and fifth inventions of the present application, the thickness of the charge injecting and transporting layer is 1.3 times or more of the thickness of the first conductive layer.
- the thickness of the charge injecting and transporting layer is 1.3 times or more of the thickness of the first conductive layer, preferably 1.5 times or more, more preferably 1.8 times or more.
- the upper limit of the thickness of the charge injecting and transporting layer is 6.0 times or less, preferably 5.0 times or less, in order to suppress absorption of light emission from the light emitting material.
- the film thickness of the first conductive layer is small, the influence of the glass defects is relatively larger than the surface defects caused by the first conductive layer.
- the film thickness is 130 nm or more, more preferably 150 nm or more, and still more preferably 200 nm or more.
- the upper limit of the thickness of the charge injecting and transporting layer is usually 1000 nm or less, preferably 700 nm or less, more preferably 500 nm or less, particularly preferably 400 nm or less in order to suppress absorption of light emission from the light emitting material.
- the film thickness of the charge injecting and transporting layer formed by the wet film forming method in the present invention is as described above, and this value is based on the film thickness of the charge injecting layer of the organic electroluminescent element produced using the conventional glass substrate. Also tend to be thick. For this reason, when the material of a glass base material is alkali glass, it is thought that the influence of alkali elution can be suppressed and it contributes also to the lifetime improvement of an organic electroluminescent element. About the material used for the positive hole injection layer 3 and the positive hole transport layer 4, what is necessary is just to use the material which has well-known hole transport property suitably.
- the materials used for the hole injection layer 3 which is the charge injection layer of the present invention are preferably as follows.
- the material used for the hole injection layer 3 is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode to the hole injection layer, and is amorphous and visible light transmissive. From this point, an aromatic amine compound is preferable, and an aromatic tertiary amine compound is particularly preferable.
- the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure.
- the aromatic tertiary amine compound it is preferable to use a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (polymerization compound in which repeating units are linked), and has a crosslinkable group. .
- a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less polymerization compound in which repeating units are linked
- the hole injection layer preferably contains an electron accepting compound because the conductivity of the hole injection layer can be improved by oxidation of the hole transporting compound.
- Specific examples of the electron-accepting compound include those described in Japanese Patent Application Laid-Open No. 2006-233162.
- Specific examples of the aromatic tertiary amine compound having a crosslinkable group include Japanese Patent Application Laid-Open No. 2009-287000. And the like.
- the materials used for the hole transport layer 4 are preferably as follows.
- the material used for the hole transport layer 4 is a material having a hole transport property, and is preferably an aromatic amine compound and particularly preferably an aromatic tertiary amine compound from the viewpoint of amorphousness and visible light transmittance.
- the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure.
- As the aromatic tertiary amine compound it is preferable to use a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (polymerization type compound in which repeating units are linked), and has a crosslinkable group. Also good.
- the hole transport layer 4 In the case of further laminating a film on the hole transport layer by a wet film formation method, it preferably has a crosslinkable group. Specific examples include those described in Japanese Patent Application Laid-Open No. 2009-287000.
- the hole transport layer 4 is formed by a wet film formation method, it is included in the charge injection transport layer in the present invention.
- the first and second inventions of the present invention include an aromatic amine polymer in which the charge injecting and transporting layer includes a crosslinked aromatic amine polymer, and the third and fourth inventions of the present invention are aromatic amine heavy compounds having a crosslinkable group.
- the charge injecting and transporting layer is formed by coating, drying, and crosslinking a composition containing a coalescence by a wet film forming method.
- the crosslinked aromatic amine polymer contained in the charge injecting and transporting layer will be described later.
- the charge injecting and transporting layer contains a crosslinked aromatic amine polymer. Leakage is prevented. The reason is considered as follows.
- the “aromatic amine polymer having a crosslinkable group” contains a crosslinkable group, it is possible to form an extremely dense organic thin film by applying a crosslinkable means after coating and drying. This results in electrostatic breakdown strength that cannot be achieved with aromatic amine polymers and other polymers that do not have crosslinkable groups. Moreover, since it is a cross-linked film, it is extremely difficult to cause elution due to the solvent contained in the coating composition even when it is coated thereon. As a result, when the second layer is further applied, the sharp and sharp corners of the protrusions and depressions covered by the first layer are exposed and the effect of applying the second layer is prevented. It will be possible.
- electrostatic breakdown (insulation breakdown) always occurs when electrons inside a solid are accelerated by an external electric field, collide with atoms constituting the solid and ionize them.
- solid breakdown occurs in a thermal breakdown mode above a certain temperature (critical temperature), and the voltage that causes solid breakdown (dielectric breakdown voltage) decreases very rapidly as the temperature increases. It has been.
- the temperature at which the breakdown voltage sharply decreases is called the critical temperature. In the breakdown phenomenon below this critical temperature, the temperature dependence of the breakdown voltage is hardly recognized.
- the dielectric breakdown voltage is proportional to the thickness of the solid sample below the critical temperature. That is, there is a dielectric breakdown electric field strength (or simply a breakdown strength) obtained by dividing the breakdown voltage by the sample thickness.
- the film thickness is 100 nm or more, short-circuit due to dielectric breakdown is unlikely to occur, but a large current flows locally due to local dielectric breakdown in the film.
- a current is measured by applying a voltage from both sides of the film, a leak can be detected as an increase in the amount of current.
- a leak occurs due to local breakdown, so that the leak is harder to cause the breakdown. Therefore, if the film thickness is the same, it is preferable that the cross-linking is less likely to leak.
- the voltage applied to obtain a required luminance is not necessarily proportional to the thickness of the organic layer including the charge transport layer and the light emitting layer. Accordingly, since the voltage is not increased by increasing the thickness of the charge transport layer, the electric field strength applied to the charge transport layer is decreased as the thickness of the charge transport layer is increased, and the dielectric breakdown is less likely to occur. It becomes difficult to leak. “Leakage is difficult” means that the probability of occurrence of leakage is reduced.
- the leak occurrence probability can be accurately estimated by increasing the number of samples and measuring.
- dielectric breakdown occurs when the voltage changes and becomes higher than the dielectric breakdown electric field strength, it is easy to detect leakage by measuring while changing the voltage applied to the sample.
- the thickness of the charge transport layer is on the order of about 100 nm. Therefore, when the applied voltage is increased to 500 nm, for example, if the applied voltage is not increased five times, the electric field strength will not be the same.
- the required luminance can be obtained by increasing the voltage by several tens of percent.
- the crosslinked film is preferable because it is less likely to leak than the uncrosslinked film.
- the layer in contact with the substrate is crosslinked so that the layer in contact with the substrate is less likely to be broken down, that is, less likely to leak.
- the charge injection layer is preferably crosslinked. Further, when it is assumed that the film is uniform and the electric field strength is the same, it can be considered that there are many places where dielectric breakdown may occur as the film thickness increases. Accordingly, when the film forming the charge injecting and transporting layer is composed of a plurality of different films, it is considered that the thicker the film is, the more dielectric breakdown occurs. Therefore, the thickest film is preferably cross-linked.
- a crosslinked aromatic amine polymer is obtained by crosslinking an aromatic amine polymer having a crosslinkable group.
- the aromatic amine polymer which has a crosslinkable group is demonstrated.
- the aromatic amine polymer having a crosslinkable group in the present invention includes a partial structure represented by the following formula (1).
- Ar a and Ar b are each independently an aromatic hydrocarbon ring group or aromatic heterocyclic group having 4 to 60 carbon atoms which may have a substituent, and Ar a represents a divalent group, and Ar b represents a monovalent group.
- the aromatic hydrocarbon ring group include a benzene ring, naphthalene ring, phenanthrene ring, anthracene ring, triphenylene ring, chrysene ring, naphthacene ring, perylene ring, coronene ring having one or two free valences, Examples thereof include 5- or 6-membered monocyclic rings or 2 to 5 condensed rings such as acenaphthene ring, fluoranthene ring, and fluorene ring, and rings in which a plurality of these rings are directly bonded.
- free valence can form bonds with other free valences as described in Organic Chemistry / Biochemical Nomenclature (above) (Revised 2nd edition, Nankodo, 1992). Say things. That is, for example, “a benzene ring having one free valence” refers to a phenyl group, and “a benzene ring having two free valences” refers to a phenylene group.
- aromatic heterocyclic group examples include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, and an indole having one or two free valences.
- the aromatic hydrocarbon ring group or the aromatic heterocyclic group is a condensed ring having one or two free valences
- the number of the condensed monocycles has high ring stability. In terms of point, it is preferably less, preferably 8 or less, and more preferably 5 or less. On the other hand, the lower limit is two.
- An aromatic hydrocarbon ring group or an aromatic heterocyclic group is specifically a benzene ring, a thiophene ring, a pyridine ring or the like having one or two free valences from the viewpoint of solubility and heat resistance.
- Monocyclic rings condensed rings such as naphthalene ring, anthracene ring, phenanthrene ring, triphenylene ring and pyrene ring, and aromatic hydrocarbon rings in which 2 to 8 aromatic rings such as fluorene ring, biphenyl and terphenyl are connected are preferable.
- a benzene ring, a fluorene ring, biphenyl, and terphenyl having one or two free valences are more preferable in terms of high solubility and high stability.
- the aromatic amine polymer to form the hole injection layer is excellent in charge transportability in charge injection property and a hole injection layer from the first conductive layer, in particular in Ar a, 1 or 2
- Ar a 1 or 2
- Most preferred are benzene rings, biphenyls, and terphenyls having one free valence.
- Examples of the substituent that the aromatic hydrocarbon ring group or aromatic heterocyclic group may have include a saturated hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon ring group having 6 to 25 carbon atoms, and a carbon number of 3 Aromatic heterocyclic group having 20 carbon atoms, diarylamino group having 12 to 60 carbon atoms, alkyloxy group having 1 to 20 carbon atoms, (hetero) aryloxy group having 3 to 20 carbon atoms, alkylthio group having 1 to 20 carbon atoms , A (hetero) arylthio group having 3 to 20 carbon atoms, a cyano group, and the like.
- a saturated hydrocarbon group having 1 to 20 carbon atoms and an aromatic hydrocarbon ring group having 6 to 25 carbon atoms are preferable from the viewpoint of solubility and heat resistance.
- examples of the saturated hydrocarbon group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, and a hexyl group.
- methyl group, ethyl group and isopropyl group are preferable, and methyl group and ethyl group are more preferable from the viewpoint of availability of raw materials and low cost.
- Examples of the monovalent aromatic hydrocarbon ring group having 6 to 25 carbon atoms include a naphthyl group such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; a phenanthyl group such as a 9-phenanthyl group and a 3-phenanthyl group; Anthryl groups such as anthryl group, 2-anthryl group, and 9-anthryl group; naphthacenyl groups such as 1-naphthacenyl group and 2-naphthacenyl group; 1-chrycenyl group, 2-chrysenyl group, 3-chrysenyl group, 4-chrysenyl group Group, chrycenyl group such as 5-chrycenyl group and 6-chrycenyl group; pyrenyl group such as 1-pyrenyl group; triphenylenyl group such as 1-triphenylenyl group;
- a phenyl group, a 2-naphthyl group and a 3-biphenyl group are preferable from the viewpoint of stability of the compound, and a phenyl group is particularly preferable from the viewpoint of ease of purification.
- Examples of the aromatic heterocyclic group having 3 to 20 carbon atoms include thienyl groups such as 2-thienyl group; furyl groups such as 2-furyl group; imidazolyl groups such as 2-imidazolyl group; carbazolyl groups such as 9-carbazolyl group; And a pyridyl group such as a 2-pyridyl group and a triazinyl group such as a 1,3,5-triazin-2-yl group.
- a carbazolyl group, particularly a 9-carbazolyl group is preferable from the viewpoint of stability.
- diarylamino group having 12 to 60 carbon atoms examples include diphenylamino group, N-1-naphthyl-N-phenylamino group, N-2-naphthyl-N-phenylamino group, and N-9-phenanthryl-N-phenylamino.
- a diphenylamino group an N-1-naphthyl-N-phenylamino group, and an N-2-naphthyl-N-phenylamino group are preferable, and a diphenylamino group is particularly preferable from the viewpoint of stability.
- alkyloxy group having 1 to 20 carbon atoms examples include methoxy group, ethoxy group, isopropyloxy group, cyclohexyloxy group, and octadecyloxy group.
- Examples of the (hetero) aryloxy group having 3 to 20 carbon atoms include substituents having an aryloxy group such as a phenoxy group, a 1-naphthyloxy group, and a 9-anthranyloxy group, and a heteroaryloxy group such as a 2-thienyloxy group Etc.
- alkylthio group having 1 to 20 carbon atoms examples include a methylthio group, an ethylthio group, an isopropylthio group, and a cyclohexylthio group.
- Examples of the (hetero) arylthio group having 3 to 20 carbon atoms include an arylthio group such as a phenylthio group, a 1-naphthylthio group and a 9-anthranylthio group, and a heteroarylthio group such as a 2-thienylthio group.
- the aromatic amine polymer in the present invention has a partial structure of an aromatic amine structure (aromatic amine structure not included in the above formula (1)) in which a group other than an aromatic hydrocarbon ring group or an aromatic heterocyclic group is bonded.
- the group other than the aromatic hydrocarbon ring group or aromatic heterocyclic group is preferably an aliphatic hydrocarbon group having 1 to 70 carbon atoms.
- the groups corresponding to Ar a and Ar b are each independently an optionally substituted aromatic hydrocarbon ring group having 4 to 60 carbon atoms.
- at least one of the groups corresponding to Ar a and Ar b is preferably an aliphatic hydrocarbon group having 1 to 70 carbon atoms.
- the aliphatic hydrocarbon group may be linear or cyclic, and may be saturated or unsaturated.
- Examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, and a cyclohexyl group.
- Group having 1 to 10 carbon atoms such as 1,8-octyl group is preferable, and a group having 1 to 8 carbon atoms is more preferable. From the viewpoint of easy synthesis, groups having 1 to 3 carbon atoms such as a methyl group, an ethyl group and an isopropyl group are particularly preferred, and groups having 1 to 2 carbon atoms such as a methyl group and an ethyl group are most preferred. preferable.
- the aliphatic hydrocarbon group is preferably a saturated hydrocarbon group from the viewpoint of redox durability.
- the aliphatic unsaturated hydrocarbon group is preferably an alkenylene group, and specific examples thereof include 1,2-vinylene group, 1,3-propenylene group, 1,2-propenylene group and 1,4-butenylene group. Etc. Among these, a vinylene group is particularly preferable because a conjugate plane is expanded by improving the planarity of the molecule, and the charge is delocalized and the stability of the compound is easily increased.
- the number of carbon atoms of the unsaturated aliphatic hydrocarbon group is preferably 2 or more from the viewpoint of planarity and charge spread, and is preferably 10 or less, and more preferably 6 or less.
- the aromatic amine polymer in the present invention is more preferably a polymer having a repeating unit represented by the following formula (11), (12), (13) or (14).
- a polymer having a repeating unit represented by the following formula (11) is synthesized by a reaction that forms an N—Ar bond such as a Buchwald-Hartwig reaction or an Ullmann reaction.
- Ar 1, Ar 3 has the same meaning as Ar a in the formula (1)
- Ar 2 has the same meaning as Ar b in the formula (1)
- Z represents a divalent group Preferably a group in which 1 to 24 groups selected from the group consisting of —CR 1 R 2 —, —CO—, —O—, —S—, —SO 2 —, —SiR 3 R 4 — are linked.
- R 1 to R 4 each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms, an aromatic hydrocarbon ring group or an aromatic heterocyclic group as defined above.
- R 1 and R 2 , R 3 and R 4 may be bonded to each other to form a ring.
- a represents an integer of 0 to 8. When a is an integer of 2 to 8, Ar 3 and Z may be different from each other.
- n represents the number of repeating units.
- Ar 1 to Ar 3 , Z, and a have the same definitions as in the formula (11).
- b represents an integer of 0 to 8.
- X 1 represents a sulfonate group such as a halogen atom or a trifluoromethanesulfonyloxy group (CF 3 SO 2 O—).
- the monomers represented by the formulas (M1-1) to (M1-3) may be used independently or in combination of two or more, and preferably ten or less.
- a polymer having a repeating unit represented by the following formula (12) is synthesized by a reaction that forms an Ar—Ar bond, such as a Yamamoto reaction, a Negishi reaction, a Migita-Kosugi-Stile reaction, or a Suzuki-Miyaura reaction.
- a reaction that forms an Ar—Ar bond such as a Yamamoto reaction, a Negishi reaction, a Migita-Kosugi-Stile reaction, or a Suzuki-Miyaura reaction.
- the upper part on the left side is a homocoupling reaction of only a halogen compound (Ullmann reaction, Yamamoto reaction, etc.), and the lower part on the left side is a cross-coupling reaction (Suzuki-Miyaura) between a halogen compound and an organic metal. Reaction, Negishi reaction, Migita-Kosugi-Still reaction, etc.).
- Ar 1 to Ar 3 , Z, a, b, X 1 , and n are formula (11), formula (M1-1) to It has the same definition as in formula (M1-3).
- G represents a zinc atom having a substituent such as BrZn- in the case of a Negishi reaction, or a substituent such as (CH 3 ) 3 Sn- in the case of a Migita-Kosugi-Stile reaction.
- a polymer having a repeating unit represented by the following formula (13) is synthesized by a reaction that forms an O—Ar bond or an S—Ar bond.
- Ar 1 to Ar 3 , Z, a, b, X 1 , and n are formula (11), formula (M1-1) to It has the same definition as in formula (M1-3).
- Q 1 represents an oxygen atom or a sulfur atom.
- Ar 1 to Ar 3 , Z, a, b, Q 1 , and X 1 are present in two or more, they are different from each other. May be.
- a polymer having a repeating unit represented by the following formula (14) is synthesized by a reaction that forms an ester bond or an amide bond.
- Ar 1 to Ar 3 , Z, a, b, and n are formula (11), formula (M1-1) to formula (M1). -3) Same definition as in In Formula (14), Formula (M4-1), and Formula (M4-2), Q 2 represents a carbonyl group or a sulfonyl group, and Q 3 represents an oxygen atom, a sulfur atom, or a —NR 5 — group (R 5 represents a hydrogen atom, an alkyl group which may have a substituent, an aromatic hydrocarbon ring group or an aromatic heterocyclic group as defined above, and X 2 represents a halogen atom. In Formula (14), Formula (M4-1), and Formula (M4-2), when Ar 1 to Ar 3 , Z, a, b, Q 2 , and Q 3 are present in two or more, they are different from each other. May be.
- the aromatic amine polymer in the present invention it is preferable to use at least one of polymers having a repeating unit represented by the formula (11) or the formula (12).
- a polymer having a repeating unit represented by is more preferable in terms of hole transportability and durability.
- a is preferably 0 from the viewpoint of excellent hole injection / transport properties.
- a is preferably 1 or 2, and more preferably 1, in terms of wide band gap and excellent hole transportability.
- Z is preferably —CR 1 R 2 — because it is excellent in durability.
- the charge injection layer includes a crosslinked aromatic amine polymer. Therefore, in this case, the aromatic amine polymer has a crosslinkable group.
- the crosslinkable group is a group that reacts with the same or different group of other molecules located nearby by irradiation of any one of heat and active energy rays to form a new chemical bond.
- the aromatic amine polymer has a crosslinkable group, the aromatic amine polymer is crosslinked by these crosslinkable groups after coating. Further, it is preferable because the aromatic amine polymer is insolubilized by being crosslinked, and a functional thin film can be further laminated on the aromatic amine polymer by coating.
- the crosslinkable group is selected from the following ⁇ Crosslinkable group T> for ease of bonding, and in this case, the crosslinked aromatic amine polymer in the present invention is selected from the crosslinkable group T. It will have a crosslinked structure derived from a crosslinkable group. ⁇ Crosslinkable group T>
- R 21 to R 25 each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.
- Ar 41 represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent.
- the benzocyclobutene ring may have a substituent.
- a cyclic ether group such as an epoxy group and an oxetane group, and a cationically polymerizable group such as a vinyl ether group are preferable in terms of high reactivity and easy crosslinking to an organic solvent.
- an oxetane group is particularly preferable in terms of easy control of the rate of cationic polymerization, and a vinyl ether group is preferable in that a hydroxyl group that may cause deterioration of the device during cationic polymerization is difficult to generate.
- an arylvinylcarbonyl group such as a cinnamoyl group or a group that undergoes cycloaddition reaction such as a benzocyclobutene ring is preferable in terms of further improving the electrochemical stability, and the structure stability after crosslinking is high.
- a benzocyclobutene ring is particularly preferred.
- the crosslinkable group may be directly bonded to (a) an aromatic hydrocarbon group or aromatic heterocyclic group in the molecule, and (b) —O—.
- —CH 2 — groups may be linked to an aromatic hydrocarbon group or an aromatic heterocyclic group via a group, and (c) one or more —CH 2 — groups optionally having a substituent may be linked.
- an aromatic hydrocarbon group or an aromatic heterocyclic group through a divalent group formed by linking these to a —O— group or —C ( ⁇ O) — group May be.
- the total number of carbon atoms of the divalent linking group is 1 to 30, preferably 1 to 20. is there.
- crosslinkable group via these divalent groups that is, a group containing a crosslinkable group
- ⁇ Group group T ′ containing a crosslinkable group> a group containing a crosslinkable group> below, but the present invention is not limited thereto. It is not something.
- ⁇ Group T ′ containing crosslinkable group> a group containing crosslinkable group>
- the aromatic amine polymer in the present invention preferably contains a partial structure consisting of the following formula (2).
- p represents an integer of 0 to 3
- Ar 21 and Ar 22 each independently represent a direct bond, an aromatic hydrocarbon group which may have a substituent, or a substituent.
- Ar 23 to Ar 25 may each independently have an optionally substituted aromatic hydrocarbon ring group or substituent.
- An aromatic heterocyclic group is represented, and T 2 represents a group containing a crosslinkable group.
- Ar 24 and Ar 25 in the formula (2), these may be the same or different.
- T 2 is selected from the above-mentioned crosslinkable group T and groups formed by linking the group of the crosslinkable group T to the divalent group (b) or (c). Among these, T 2 is preferably selected from the above-mentioned crosslinkable group T and group T ′ containing a crosslinkable group. In addition, T 2 is particularly preferably a group containing a group represented by the following formula (3).
- the benzocyclobutene ring in formula (3) may have a substituent.
- the substituents may be bonded to each other to form a ring.
- the aromatic amine polymer in this invention may contain the partial structure which consists of following formula (4).
- R 1 and R 2 are each independently a hydrogen atom, an aromatic hydrocarbon ring group which may have a substituent, or an aromatic heterocycle which may have a substituent.
- n represents an integer of 0 to 3
- Ar 1 represents an aromatic hydrocarbon ring group which may have a substituent, or an aromatic heterocyclic group which may have a substituent
- Ar 2 represents a direct bond, an aromatic hydrocarbon ring group which may have a substituent, or an aromatic heterocyclic group which may have a substituent,
- Ar 3 to Ar 5 each independently represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent.
- T represents a group containing a crosslinkable group.
- Ar 4 and Ar 5 in the formula (4) these may be the same or different from each other.
- the aromatic hydrocarbon group which may have a substituent which can be used for Ar 1 , Ar 2 and Ar 4 , or the aromatic heterocyclic group which may have a substituent is represented by the formula (1 ) Is the same as the structure represented by Ar a .
- the aromatic hydrocarbon group which may have a substituent which can be used for Ar 3 and Ar 5 , or the aromatic heterocyclic group which may have a substituent is represented by Ar in the above formula (1). It is the same as the structure represented by b .
- T examples include the same groups as T 2 in the formula (2), and it is preferably selected from the above-described crosslinkable group T and group T ′ containing a crosslinkable group.
- T is particularly preferably a group containing a group represented by the formula (3).
- aromatic amine polymer in the present invention preferably includes a partial structure represented by the following formula (5).
- Ar 6 and Ar 7 each independently represent a divalent aromatic ring group that may have a substituent
- Ar 8 represents an aromatic that may have a substituent
- R 8 and R 9 each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms, or an optionally substituted carbon group having 1 to 12 represents an alkoxy group having 12 carbon atoms, an aromatic hydrocarbon group having 6 to 25 carbon atoms which may have a substituent, or an aromatic heterocyclic group having 3 to 20 carbon atoms which may have a substituent.
- R 8 and R 9 may be bonded to each other to form a ring.
- p represents an integer of 1 to 5.
- aromatic amine polymer in the present invention preferably includes a partial structure consisting of the following formula (6).
- Ar 31 , Ar 33 , Ar 34 and Ar 35 each independently have a divalent aromatic hydrocarbon ring group or substituent which may have a substituent.
- Ar 32 represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent.
- R 11 represents an optionally substituted alkyl group having 1 to 12 carbon atoms or an optionally substituted alkoxy group having 1 to 12 carbon atoms
- R 12 to R 17 each represents Independently, it may have a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms, an optionally substituted alkoxy group having 1 to 12 carbon atoms, or a substituent.
- R 12 and R 13 , R 14 and R 15 , and R 16 and R 17 may be bonded to each other to form a ring.
- l, m and n each independently represents an integer of 0 to 2.
- the divalent aromatic hydrocarbon group which may have a substituent which can be used for Ar 31 , Ar 33 , Ar 34 , Ar 35 and Ar 6 , Ar 7 can be used for the aforementioned Ar a. It is the same as a divalent aromatic hydrocarbon group.
- the aromatic hydrocarbon group which may have a substituent which can be used for Ar 32 and Ar 8 is the same as the aromatic hydrocarbon group which can be used for Ar b described above.
- R 12 to R 17 and R 8 and R 9 each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent.
- An aromatic group that may be present, may be bonded to each other to form a ring.
- R 11 , R 12 to R 17, and R 8 and R 9 are preferably an alkyl group having 1 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms, and an alkyl group having 1 to 12 carbon atoms from the viewpoint of solubility. Groups are more preferred.
- the substituent which Ar 31 , Ar 33 , Ar 34 , Ar 35 , Ar 6 , Ar 7 , R 12 to R 17 , R 8 , R 9 may have is represented by the aforementioned Ar a or Ar b.
- the substituent which the aromatic hydrocarbon group or aromatic heterocyclic group which may have, or the said crosslinkable group is mentioned.
- the aromatic amine polymer in the present invention has partial structures represented by the formulas (1), (11), (12), (13), (14), (2), (4), (5), (6), A polymer having a partial structure selected from a divalent benzene ring and an aromatic hydrocarbon which is a divalent 5- or 6-membered monocyclic ring or a 2-5 condensed ring is preferable.
- the aromatic amine polymer in the present invention has a partial structure represented by formulas (1), (11), (12), (13), (14), (2), (4), (5), (6)
- a polymer comprising a partial structure selected from a divalent benzene ring and an aromatic hydrocarbon which is a divalent 6-membered 2- to 5-fused ring is preferable.
- the weight average molecular weight (Mw) of the aromatic amine polymer in the present invention is usually 3,000,000 or less, preferably 1,000,000 or less, more preferably 500,000 or less, and usually 2,000 or more. , Preferably 3,000 or more, more preferably 5,000 or more.
- the number average molecular weight (Mn) of the aromatic amine polymer in the present invention is usually 3,000 or more, preferably 6,000 or more, and usually 1,000,000 or less, preferably 500,000 or less. .
- the dispersity (Mw / Mn) of the aromatic amine polymer in the present invention is usually 3.5 or less, preferably 2.5 or less, more preferably 2.0 or less.
- this weight average molecular weight is determined by SEC (size exclusion chromatography) measurement. In SEC measurement, the elution time is shorter for higher molecular weight components, and the elution time is longer for lower molecular weight components.
- SEC size exclusion chromatography
- the composition for forming a hole injecting and transporting layer used for forming the hole injecting and transporting layer includes a solvent capable of dissolving or dispersing the above-described aromatic amine polymer having a crosslinkable group and other components as necessary. Prepared by mixing.
- the solvent contained in the composition for forming a hole injecting and transporting layer is particularly limited. However, it is a solvent that dissolves the aromatic amine polymer in an amount of usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1.0% by mass or more at 25 ° C. and 1 atm. .
- the solvent contained in the composition for forming a hole injecting and transporting layer is not particularly limited as long as it satisfies the above required characteristics, and is an ester solvent, an aromatic hydrocarbon solvent, an ether solvent, an alkane solvent, a ketone solvent. Solvents, alcohol solvents, halogen-containing organic solvents, amide solvents, etc. can be used, and ester solvents, aromatic hydrocarbon solvents, ether solvents, alkane solvents, ketone solvents are highly soluble and residual. Less adverse effect of solvent is preferable.
- ester solvents include aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate, and phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and benzoic acid. and aromatic esters such as n-butyl.
- aromatic hydrocarbon solvent examples include toluene, xylene, mesitylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, and methylnaphthalene.
- ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole.
- ether solvents such as aromatic ethers such as phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole and 2,4-dimethylanisole.
- alkane solvent examples include n-decane, cyclohexane, ethylcyclohexane, decalin, bicyclohexane and the like.
- ketone solvent examples include alicyclic ketones such as cyclohexanone, cyclooctanone, and fenkon, and aliphatic ketones such as methyl ethyl ketone and dibutyl ketone.
- the alcohol solvent examples include alicyclic alcohols such as cyclohexanol and cyclooctanol, and aliphatic alcohols such as butanol and hexanol.
- halogen-containing organic solvent examples include 1,2-dichloroethane, chlorobenzene and o-dichlorobenzene.
- amide solvent examples include N, N-dimethylformamide and N, N-dimethylacetamide. In addition to these, dimethyl sulfoxide and the like can also be used. These solvents may be used alone or in combination of two or more in any combination and ratio. In order to obtain a more uniform film, it is preferable that the solvent evaporates from the liquid film immediately after the film formation at an appropriate rate. For this reason, the boiling point of the solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher.
- the boiling point of the solvent is usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 ° C. or lower. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. Further, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying process, which may adversely affect other layers and the substrate.
- the amount of the solvent contained in the composition for forming a hole injection transport layer is usually 10% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 80% by mass or more. Usually, it is 99.99 mass% or less.
- the amount of the aromatic amine polymer contained in the composition for forming a hole injecting and transporting layer is preferably larger in terms of increasing the viscosity of the composition, but is preferably smaller in terms of solubility.
- the amount of the aromatic amine polymer contained in the composition for forming a hole injecting and transporting layer is usually 0.01% by mass or more, preferably 0.1% by mass or more, It is more preferably 0.5% by mass or more, and on the other hand, it is usually 50% by mass or less, preferably 40% by mass or less, and more preferably 20% by mass or less.
- 2 or more types of aromatic amine polymers may be contained in the composition for positive hole injection transport layer formation, In that case, it is preferable that the sum total of 2 or more types becomes said range.
- the hole injection transport layer 11 of the present invention is formed by a wet film formation method.
- the wet film-forming method is, for example, a spin coating method, a dip coating method, a die coating method, a bar coating method, a blade coating method, a roll coating method, a spray coating method, a capillary coating method, an inkjet method.
- a method of forming a film by adopting a wet film forming method such as a printing method, a nozzle printing method, a screen printing method, a gravure printing method, or a flexographic printing method, and drying the coated film.
- spin coating, spray coating, ink jet, nozzle printing, and the like are preferable.
- the hole injecting and transporting layer 11 of the present invention is formed by a wet film forming method.
- the hole injection transport layer forming composition has an aromatic amine polymer having a crosslinkable group and the hole injection transport layer (charge injection transport layer) has a cross-linked aromatic amine polymer.
- the step of crosslinking the hole injecting and transporting layer forming composition film and the aromatic amine polymer may be divided into two steps, or the same step.
- heating is usually performed.
- the heating method is not particularly limited, but the conditions for heat drying are usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 150 ° C. or higher, and usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably.
- the heating time is usually 1 second or longer, preferably 10 hours or shorter.
- Means such as mounting the laminated body which has the formed film
- a method of irradiating directly using an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp, an infrared lamp, or the above-mentioned light source is incorporated.
- an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp, an infrared lamp, or the above-mentioned light source is incorporated.
- Examples include a mask aligner and a method of irradiation using a conveyor type light irradiation device.
- active energy irradiation other than light for example, there is a method of irradiation using a device that irradiates a microwave generated by a magnetron, a so-called microwave oven.
- heating with infrared rays is particularly preferable.
- a halogen heater, a ceramic-coated halogen heater, a ceramic heater, or the like can be used.
- the halogen heater include Ushio Electric Co., Ltd. (UH-USC, UH-USD, UH-MA1, UH-USF, UH-USP, UH-USPN, and halogen coaters in which these are ceramic coated (black coat)), The product made from Heraeus etc. is mentioned.
- a far-infrared heater for example, there is a product manufactured by AMK (far-infrared panel type clean heater).
- the infrared heater is installed on the top of the substrate and infrared heating is performed can be used.
- the infrared transmission of the substrate preferably has a minimum value in the wavelength range of 2000 nm to 3300 nm.
- the upper limit of the infrared transmittance is usually 95% or less, preferably 90% or less, more preferably 85% or less, still more preferably 80% or less, and particularly preferably 75% or less.
- the lower limit is usually 5% or more, preferably 10% or more, more preferably 20% or more, and further preferably 25% or more.
- the substrate is heated moderately, and the composition film for forming the hole injection transport layer is heated by the heat conduction. That is, with the thickness of the substrate, the composition film for forming a hole injection / transport layer can be heated appropriately, and the performance of the hole injection / transport layer type can be improved. Moreover, when the composition film for forming a hole injecting and transporting layer is heated too much, it can be a heat bath that appropriately releases heat.
- the lower limit of the peak wavelength of the infrared heater is usually 0.8 ⁇ m or more, preferably 0.9 ⁇ m or more, more preferably 1 ⁇ m or more, and particularly preferably 1.1 ⁇ m or more.
- the upper limit is 25 ⁇ m or less, preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, and particularly preferably 3 ⁇ m or less.
- the composition film for forming a hole injection transport layer can be heated by absorbing infrared rays. Further, the substrate is appropriately heated by the peak wavelength of the infrared heater in this range, and the composition film for forming the hole injection transport layer can be heated with the heat. In addition, when an organic material is used for the composition for forming the hole injection transport layer, the organic material absorbs infrared rays from the infrared heater, and the composition film for forming the hole injection transport layer can be heated by infrared induction heating. it can.
- the infrared transmittance of the substrate has a minimum value of transmittance in the wavelength range of 2000 to 3300 nm, and the wavelength at the minimum value and the peak wavelength of the infrared heater.
- the lower limit of the product ( ⁇ ) is usually 2 ⁇ m 2 or more, preferably 2.5 ⁇ m 2 or more, more preferably 3 ⁇ m 2 or more.
- the upper limit thereof is generally, 16 [mu] m 2 or less, preferably 15.5 2 or less, more preferably 15 [mu] m 2 or less.
- the composition film for forming the hole injection transport layer can be appropriately heated and conductive.
- the performance of the thin film can be enhanced. The reason why the product ( ⁇ ) of the wavelength at the minimum value of the infrared transmittance of the substrate and the peak wavelength of the infrared heater is used as a parameter for specifying the invention will be described below.
- the minimum wavelength in the range of 2000 to 3300 nm in the infrared absorption of the substrate can be appropriately heated without overheating the substrate.
- the infrared heater for heating the substrate includes a peak wavelength of the infrared heater as a typical value indicating the characteristics.
- the relationship between the wavelength and the energy is inversely proportional, so that the smaller the value of this parameter ( ⁇ ), the greater the energy that can be obtained from the substrate.
- the larger the value of the parameter ( ⁇ ) the lower the energy obtained by the substrate.
- This parameter serves as an index in the present invention.
- the layer formed of the composition for forming a hole injection transport layer When the layer formed of the composition for forming a hole injection transport layer is formed on the anode, the layer in contact with the anode functions as a hole injection layer.
- the said composition for positive hole injection transport layer formation contains an electron-accepting compound.
- the hole injection layer preferably contains an electron accepting compound because the conductivity of the hole injection layer can be improved by oxidation of the hole transporting compound.
- the electron-accepting compound a compound having an oxidizing power and the ability to accept one electron from the above-described hole-transporting compound is preferable, and specifically, a compound having an electron affinity of 4 eV or more is preferable. More preferably, the compound is 5 eV or more.
- electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids.
- examples thereof include one or more compounds selected from the group. Specifically, an onium salt substituted with an organic group such as triphenylsulfonium tetrafluoroborate; iron (III) chloride (Japanese Unexamined Patent Publication No.
- a high-valent inorganic compound such as ammonium peroxodisulfate
- a cyano compound such as tetracyanoethylene
- an aromatic boron compound such as tris (pentafluorophenyl) borane
- an ionic compound described in International Publication No. 2005/089024
- a fullerene derivative And iodine
- an onium salt substituted with an organic group, an inorganic compound having a high valence, and the like are preferable in terms of having strong oxidizing power.
- an onium salt substituted with an organic group, a cyano compound, an aromatic boron compound, and the like are preferable from the viewpoint of high solubility in an organic solvent and easy formation of a film by a wet film formation method.
- Specific examples of the onium salt, cyano compound or aromatic boron compound substituted with an organic group suitable as an electron-accepting compound include those described in International Publication No. 2005/089024, and preferred examples thereof are also the same. .
- n1 in the following general formula (I-1), n2 in the following general formula (I-2), and n3 in the following general formula (I-3) are each independently a counter anion Z n1 to Z n3.
- - is any positive integer corresponding to the valency.
- the values of n1 to n3 are not particularly limited, but all are preferably 1 or 2, and most preferably 1.
- an electron-accepting compound may be used individually by 1 type, or may be used 2 or more types by arbitrary combinations and a ratio.
- the content of the electron-accepting compound in the composition for forming a hole injection layer is usually 0.01% by mass or more, preferably 0.05% by mass or more, usually 20% by mass or less, preferably 10% by mass or less.
- 2 or more types of electron-accepting compounds may be contained, In that case, it is preferable that the sum total of 2 or more types becomes said range.
- the content of the electron-accepting compound with respect to the aromatic amine polymer in the composition for forming a hole injection layer is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 100% by mass or less. Preferably it is 40 mass% or less.
- the hole injection layer preferably contains a cation radical compound in terms of enhancing the hole injecting property from the anode and enhancing the hole transporting property.
- a cation radical compound an ionic compound composed of a cation radical which is a chemical species obtained by removing one electron from a hole transporting compound and a counter anion is preferable.
- the cation radical is derived from a hole transporting aromatic amine polymer, the cation radical has a structure in which one electron is removed from the aromatic amine structure of the aromatic amine polymer.
- the cation radical is preferably a chemical species obtained by removing one electron from the compound described above as the hole transporting compound from the viewpoints of amorphousness, visible light transmittance, heat resistance, solubility, and the like.
- the cation radical compound can be generated by mixing the hole transporting compound and the electron accepting compound. That is, by mixing the hole transporting compound and the electron accepting compound, electron transfer occurs from the hole transporting compound to the electron accepting compound, and the cation radical and the counter anion of the hole transporting compound A cation ion compound consisting of
- the light emitting layer contains at least a material having a light emitting property (light emitting material), and preferably further contains a material having a charge transporting property (charge transporting material).
- the light emitting material emits light at a desired light emission wavelength, and is not particularly limited as long as the effect of the present invention is not impaired, and a known light emitting material can be applied.
- the light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, but a material having good light emission efficiency is preferable, and a phosphorescent light emitting material is preferable from the viewpoint of internal quantum efficiency.
- Examples of the phosphorescent material include organometallic complexes containing a metal selected from Groups 7 to 11 of the long-period periodic table.
- Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold, with iridium or platinum being particularly preferred.
- a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or (hetero) arylpyrazole ligand and a pyridine, pyrazole, phenanthroline, or the like is connected is preferable.
- a phenylpyridine ligand and a phenylpyrazole ligand are preferable.
- These ligands may further have a substituent.
- (hetero) aryl represents an aryl group or a heteroaryl group.
- the charge transport material is a material having positive charge (hole) and / or negative charge (electron) transport properties, and is not particularly limited as long as the effects of the present invention are not impaired, and a known light-emitting material can be applied. is there.
- As the charge transporting material a compound or the like conventionally used in a light emitting layer of an organic electroluminescence device can be used, and a compound used as a host material of the light emitting layer is particularly preferable.
- the method for forming the light emitting layer may be a vacuum deposition method or a wet film formation method, but a wet film formation method is preferred because of its excellent film formability.
- a wet film formation method is preferred because of its excellent film formability.
- the light-emitting layer forming composition prepared by mixing the material to be mixed with a solvent is used.
- the cathode in this embodiment is the second conductive layer in the present invention.
- the cathode 9 is an electrode that serves to inject electrons into the layer on the light emitting layer 5 side.
- the material of the cathode 9 is usually a metal such as aluminum, gold, silver, nickel, palladium or platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, Alternatively, it is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline. Among these, a metal having a low work function is preferable for efficient electron injection.
- a suitable metal such as tin, magnesium, indium, calcium, aluminum, silver, or an alloy thereof is used.
- Specific examples include low work function alloy electrodes such as magnesium-silver alloys, magnesium-indium alloys, and aluminum-lithium alloys.
- the material of a cathode only 1 type may be used for the material of a cathode, and 2 or more types may be used together by arbitrary combinations and a ratio.
- a method for forming the cathode 9 a known method may be appropriately used depending on the above materials, but a vacuum deposition method, a sputtering method, or the like is preferably used.
- the film thickness of the cathode 9 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the cathode 9 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the cathode 9 is arbitrary. Furthermore, it is also possible to laminate different conductive materials on the cathode 9 described above.
- the work function is further high against the atmosphere. It is preferable to stack a stable metal layer because the stability of the device is increased.
- metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used.
- these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
- the organic electroluminescent element of the present invention may have another functional layer between the essential layers. Examples of other functional layers are shown below.
- (Hole blocking layer) A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later.
- the hole blocking layer 6 is a layer that also plays a role of blocking holes moving from the anode 2 from reaching the cathode 9 in the electron transport layer.
- the hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.
- the hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5.
- the physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, large energy gap (difference between HOMO and LUMO), excited triplet energy level (T1). ) Is high.
- Examples of the material of the hole blocking layer 6 satisfying such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum.
- the hole blocking layer 6 can be formed by a wet film formation method, a vacuum evaporation method, or other methods.
- the film thickness of the hole blocking layer 6 is arbitrary as long as the effects of the present invention are not significantly impaired.
- the thickness of the hole blocking layer 6 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.
- the electron transport layer 7 is a layer for transporting electrons provided between the light emitting layer and the cathode.
- an electron transport material for the electron transport layer 7 usually, a compound that has high electron injection efficiency from the cathode or the adjacent layer on the cathode side and that has high electron mobility and can efficiently transport injected electrons. Is used.
- the compound satisfying such conditions include metal complexes such as 8-hydroxyquinoline aluminum complex and lithium complex (Japanese Patent Laid-Open No.
- Examples of the electron transporting material used for the electron transporting layer include electron transporting organic compounds represented by metal complexes such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and aluminum complexes of 8-hydroxyquinoline, sodium, potassium, and the like.
- an alkali metal such as cesium, lithium, rubidium (described in Japanese Laid-Open Patent Publication No. 10-270171, Japanese Laid-Open Patent Publication No. 2002-1000047, Japanese Laid-Open Patent Publication No. 2002-1000048, etc.)
- an inorganic salt such as lithium fluoride or cesium carbonate.
- FIG. Therefore, it can be formed by a wet film formation method, a vacuum deposition method, or other methods.
- the thickness of the electron transport layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.
- an electron injection layer 8 may be provided between the electron transport layer 7 and a cathode 9 described later.
- the electron injection layer 8 is made of an inorganic salt or the like. Examples of the material of the electron injection layer 8 include lithium fluoride (LiF), magnesium fluoride (MgF 2 ), lithium oxide (Li 2 O), cesium carbonate (II) (CsCO 3 ), and the like (Applied Physics Letters). , 1997, Vol. 70, pp. 152; Japanese Unexamined Patent Publication No. 10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.).
- the electron injection layer 8 there is no limitation on the method of forming the electron injection layer 8. Therefore, it can be formed by a wet film formation method, a vacuum deposition method, or other methods. Since the electron injection layer 8 is often not accompanied by charge transport properties, it is preferably used as an ultrathin film for efficient electron injection, and the film thickness is usually 0.1 nm or more, preferably 5 nm or less. is there.
- short in the present invention means that although the applied current increases substantially in proportion to the voltage, the light emission luminance does not increase proportionally with the energization current and hardly emits light. Therefore, the shorted element has low luminance or does not emit light, and thus does not function sufficiently as an organic electroluminescent element.
- the leakage in the present invention refers to a phenomenon in which an excessive current flows with respect to an applied voltage as compared with an originally assumed current value.
- a method of measuring an electrical element defect such as a short circuit or a leak a method of observing and measuring a light emission state while connecting an external power source to a power supply terminal of a completed organic electroluminescence device and energizing is usually used. At this time, if short-circuited, the current increases substantially in proportion to the voltage, but the light emission luminance does not increase proportionally with the energization current and emits little light. Therefore, it is relatively easy to determine a shorted element.
- the organic electroluminescence device of the same configuration has a small emission area (according to the density of surface defects that can cause, Producing a large number of organic field elements in advance (probably reducing the cause of leakage), measuring the current efficiency of the light emission luminance, and comparing it with the current efficiency of the light emission luminance of the organic electroluminescence element to be determined whether it is leaking There is.
- Another approach is to use such voltage-current due to the fact that organic electroluminescent devices that are prone to leak or are leaking are unstable and spikes and steps are likely to occur in their voltage-current density graph.
- the details of the leak determination method are as described in the examples described later.
- the absolute change in current per -0.1V within the applied voltage range on the left The ratio of the value to the current value with the lower absolute value of the voltage (hereinafter referred to as Z) is calculated in%, and even if the value of Z exceeds 20% is obtained in the entire measured voltage range In the case of “leak”, the case where all values were 20% or less was determined to be “no leak”.
- Judgment was made in accordance with Judgment of presence or absence of leak occurrence-1. However, it was determined that “leak” was obtained when even one value exceeding 50% of Z was obtained, and “no leak” was designated when all values were 50% or less.
- the glass substrates A to E and I were formed by depositing ITO on a non-polished glass substrate manufactured by the float method by sputtering using an SiO 2 barrier layer of about 20 nm (glass substrate I is 150 nm).
- the glass substrate F and the glass substrate G are glass substrates obtained by directly depositing an ITO film with a thickness of 110 nm by a sputtering method on an unpolished glass substrate manufactured by a fusion method, and the glass substrate H is a float. This is a glass base material obtained by polishing only the glass base material manufactured by the method.
- the glass substrates used in the organic electroluminescence device of the present invention are A to E and I which are manufactured by the float process and are not polished.
- the minimum value of the undulation tangent is 4.00 ⁇ 10 ⁇ 6 or more, further 4.02 ⁇ 10 ⁇ 6 or more, and the maximum value of the undulation tangent is 22 ⁇ 10 ⁇ 6 or more.
- the content of Na 2 O is either 2.0 mass% or more. Further, the density of surface defects is 2.0 pieces / cm 2 or more.
- the minimum value of the undulation tangent is less than 4.02 ⁇ 10 ⁇ 6 , and It is less than 00 ⁇ 10 ⁇ 6 and the maximum waviness tangent is less than 22 ⁇ 10 ⁇ 6 .
- the density of the surface defect of the glass substrate F manufactured by the fusion method is less than 2.0 pieces / cm ⁇ 2 >.
- Example 1-1 From the layer configuration shown in FIG. 1, an organic electroluminescence device having a 9 mm square light emitting region having a structure in which the hole blocking layer 6 and the electron transport layer 7 are omitted was produced.
- a glass substrate A on which an ITO film with a thickness of 110 nm was formed as an anode was prepared by patterning ITO so that the light emitting area was 9 mm square.
- Example 1-1 ⁇ Formation of cathode> Subsequently, aluminum was vapor-deposited by a vacuum evaporation method so that it might become a film thickness of 80 nm, and the cathode was formed. ⁇ Sealing process> Subsequently, in a nitrogen glove box, a photocurable resin was applied to the outer periphery of the glass plate, and a moisture getter sheet was installed in the center. The glass plate and the element formed up to the second electrode 4 were bonded together, and then the ultraviolet light was applied only to the region where the photocurable resin was applied to cure the resin. Thereby, an organic electroluminescent element was obtained. In Example 1-1, only the hole injection layer is wet-formed, so that only the hole injection layer corresponds to the charge injection / transport layer of the present invention.
- Example 2-1 An organic electroluminescent device was produced in the same manner as in Example 1-1 except that the hole injection layer was spin-coated at 1950 rpm for 30 seconds to form a 200 nm-thick hole injection layer.
- Example 3-1 An organic electroluminescence device was prepared in the same manner as in Example 1-1 except that the hole injection layer was spin-coated at 910 rpm for 30 seconds to form a 400 nm-thick hole injection layer.
- Example 4-1 The hole injection / transport layer was spin-coated at 1050 rpm for 30 seconds using a solution having a composition concentration of 6.5 wt% to form an organic layer as in Example 1-1, except that a 500 nm-thick hole injection layer was formed. An electroluminescent element was prepared.
- Example 1-1 An organic electroluminescence device was prepared in the same manner as in Example 1-1 except that the hole injection / transport layer was spin-coated at 5500 rpm for 30 seconds to form a 100 nm-thick hole injection layer.
- Example 1-1 An organic electroluminescent element was produced in the same manner as in Example 1-1 except that a hole injecting and transporting layer having a thickness of 30 nm was formed using a glass substrate F produced by the fusion method.
- an inexpensive glass substrate that is manufactured by the float process and does not perform polishing that is, the minimum value of the undulation tangent is 4.20 ⁇ 10 ⁇ 6 or more or the maximum value of the undulation tangent is 22 ⁇ 10 ⁇ 6 or more.
- the film thickness of the anode It is possible to produce a leak-free organic electroluminescent element by wet-forming a 1.3 times or more hole injection layer (the fourth and fifth inventions of the present application), and the anode film thickness is 1 It has been found that an organic electroluminescence device free from leakage can be produced at a rate equal to or higher than that of a conventional expensive glass substrate by wet-forming a hole injection layer of .8 times or more.
- an inexpensive glass substrate that is manufactured by the float process and does not perform polishing that is, the minimum value of waviness tangent is 4.00 ⁇ 10 ⁇ 6 or more or the maximum value of waviness tangent is 22 ⁇ 10 ⁇ 6 or more.
- the anode has a film thickness of 130 nm or more, and the charge injection layer contains a crosslinked aromatic amine polymer (the first of the present application). (Invention), it was found that it is possible to produce an organic electroluminescence device free from leakage at a rate equal to or higher than that of a conventional expensive glass substrate.
- Example 1-2 to Example 4-2, Comparative Example 1-2, and Reference Example 1-2 In the same manner as Example 1-1 to Example 4-1, Comparative Example 1-1, and Reference Example 1-1, Example 1-2 to Example 4-2, Comparative Example 1-2, and Reference Example 1-2 The organic electroluminescence device was manufactured and the presence / absence of leakage was determined by ⁇ Determination of leakage occurrence-2>. The results are shown in Table 14.
- Example 5 From the layer structure shown in FIG. 1, an organic electroluminescent element having a 7 mm square light emitting region having a structure in which the hole blocking layer 6 and the electron transport layer 7 are omitted was produced.
- ⁇ Formation of coating type hole injection transport layer on ITO substrate> First, a glass substrate I on which an ITO film having a thickness of 150 nm was formed as an anode was prepared by patterning ITO so that the light emitting area was 7 mm square.
- a composition dissolved in ethyl benzoate was prepared so that the total concentration of the mixture was 5.0% by mass.
- This composition was spin-coated at 6000 rpm for 30 seconds on the glass substrate I in an air atmosphere.
- the hole injection layer with a film thickness of 73 nm was formed by heating at 230 degreeC for 1 hour.
- This composition was spin-coated at 2950 rpm for 120 seconds on the glass substrate I on which the hole injection layer was formed in a nitrogen atmosphere. Then, the coating type positive hole transport layer with a film thickness of 57 nm was formed by heating at 230 degreeC under nitrogen atmosphere for 1 hour. Next, a vapor deposition type hole transport layer was produced by vacuum vapor deposition of 4,4′-bis [N- (9-phenanthryl) -N-phenyl-amino] biphenyl (PPD) shown below to a film thickness of 45 nm. Filmed.
- Example 5 ⁇ From formation of light emitting layer to sealing process> Next, the formation from the light emitting layer to the sealing step was carried out in the same manner as in Example 1-1 to produce an organic electroluminescent element.
- Example 5 since the hole injection layer and the coating type hole transport layer are wet-formed, the hole injection layer and the coating type hole are equivalent to the charge injection transport layer of the present invention. It is a transport layer.
- Example 6 A hole injection layer is spin-coated at 4200 rpm for 30 seconds to form a 88 nm-thick hole injection layer, and a coating-type hole transport layer is spin-coated at 2250 rpm for 120 seconds to form a 62-nm thick coating-type hole transport.
- An organic electroluminescent element was produced in the same manner as in Example 5 except that the layer was formed.
- Example 7 The hole injection layer is spin-coated at 2500 rpm for 30 seconds to form a 122 nm-thick hole injection layer, and the coating-type hole transport layer is spun at 3200 rpm for 120 seconds using a solution having a composition concentration of 4.0 wt%.
- An organic electroluminescent element was produced in the same manner as in Example 5 except that a coated hole transport layer having a thickness of 79 nm was formed by coating.
- Example 8 The hole injection layer was spin-coated at 4300 rpm for 30 seconds using a solution having a composition concentration of 7.0 wt% to form a hole injection layer having a thickness of 187 nm, and a coating type hole transport layer An organic electroluminescent device was fabricated in the same manner as in Example 5 except that a coating-type hole transport layer having a film thickness of 118 nm was formed by spin coating at 3500 rpm for 120 seconds using a solution having a composition concentration of 5.0 wt%. .
- Example 9 The hole injection layer is spin-coated at 2750 rpm for 30 seconds to form a 245 nm-thick hole injection layer, and the coating-type hole transport layer is spin-coated at 2500 rpm for 120 seconds, and the coating-type hole transport is 158 nm thick.
- An organic electroluminescent element was produced in the same manner as in Example 8 except that the layer was formed.
- Example 10 The hole injection layer is spin-coated at 2150 rpm for 30 seconds to form a 303 nm-thick hole injection layer, and the coating-type hole transport layer is spun at 2500 rpm for 120 seconds using a solution with a composition concentration of 6.0 wt%.
- An organic electroluminescent element was produced in the same manner as in Example 8 except that a coating-type hole transport layer having a thickness of 198 nm was formed by coating.
- a hole injection layer was spin-coated at 3500 rpm for 30 seconds using a solution having a composition concentration of 2.5 wt% to form a 32 nm-thick hole injection layer, and a coating-type hole transport layer was formed with a composition concentration of 2
- a 0.0 wt% solution was spin-coated at 3500 rpm for 120 seconds to produce an organic electroluminescent device in the same manner as in Example 5 except that a coating-type hole transport layer having a thickness of 28 nm was formed.
- the hole injection layer was spin-coated at 2600 rpm for 30 seconds using a solution having a composition concentration of 3.5 wt% to form a 61 nm-thick hole injection layer, and the coating type hole transport layer was formed at 3800 rpm for 120 seconds.
- An organic electroluminescent element was produced in the same manner as in Example 5 except that a coating-type hole transport layer having a film thickness of 44 nm was formed by spin coating.
- Example 11 An organic electroluminescent element was produced in the same manner as in Example 5 except that the hole injection layer and the coating type hole transport layer were formed as follows.
- a composition dissolved in ethyl benzoate was prepared so that the total concentration of the mixture was 5.0% by mass. This composition was spin-coated at 2200 rpm for 30 seconds on the glass substrate I in an air atmosphere. Then, the hole injection layer with a film thickness of 93 nm was formed by heating at 230 degreeC for 1 hour.
- the coating type hole transport layer was formed in the same manner as in Example 6 except that a coating type hole transport layer having a film thickness of 56 nm was formed by spin coating at 2100 rpm for 120 seconds.
- Example 4 An organic electroluminescent element was produced in the same manner as in Example 5 except that the hole injection layer and the coating type hole transport layer were formed as follows.
- a composition dissolved in ethyl benzoate was prepared so that the total concentration of the mixture was 4.0% by mass. This composition was spin-coated at 3100 rpm for 30 seconds on the glass substrate I in an air atmosphere. Then, the hole injection layer with a film thickness of 59 nm was formed by heating at 230 degreeC for 1 hour.
- the coating type hole transport layer was formed in the same manner as in Example 7 except that a coating type hole transport layer having a film thickness of 41 nm was formed by spin coating at 4500 rpm for 120 seconds.
- the hole injection layer is spin-coated at 3400 rpm for 30 seconds using a solution having a composition concentration of 5.0 wt% to form a 79 nm-thick hole injection layer, and the coating-type hole transport layer has a composition concentration of 3
- a 0.0 wt% solution was spin-coated at 2950 rpm for 120 seconds to produce an organic electroluminescent device in the same manner as in Comparative Example 4 except that a coating-type hole transport layer having a thickness of 50 nm was formed.
- a hole injection layer is spin-coated at 2700 rpm for 30 seconds to form a 92 nm-thick hole injection layer, and a coating-type hole transport layer is spin-coated at 2950 rpm for 120 seconds to form a 59-nm-thick coating-type hole transport.
- An organic electroluminescent element was produced in the same manner as in Comparative Example 5 except that the layer was formed.
- the hole injection layer was spin-coated at 2300 rpm for 30 seconds using a solution having a composition concentration of 5.0 wt% to form a 107 nm-thick hole injection layer, and the coating-type hole transport layer was formed at 3000 rpm for 120 seconds.
- An organic electroluminescent element was produced in the same manner as in Comparative Example 4 except that a coating-type hole transport layer having a film thickness of 85 nm was formed by spin coating.
- the hole injection layer was spin-coated at 2300 rpm for 30 seconds using a solution with a composition concentration of 7.0 wt% to form a hole injection layer with a film thickness of 183 nm.
- a 0.0 wt% solution was spin-coated at 2300 rpm for 120 seconds to produce an organic electroluminescent device in the same manner as in Comparative Example 5 except that a coating-type hole transport layer having a thickness of 118 nm was formed.
- the hole injection layer was spin-coated using a solution having a composition concentration of 8.0 wt% at 2750 rpm for 30 seconds to form a 232 nm-thick hole injection layer, and the coating type hole transport layer was formed at 2000 rpm for 120 seconds.
- An organic electroluminescent element was produced in the same manner as in Comparative Example 8 except that a coating-type hole transport layer having a film thickness of 158 nm was formed by spin coating.
- the hole injection layer was spin-coated at 2050 rpm for 30 seconds to form a 301 nm-thick hole injection layer, and the coating-type hole transport layer was used at a solution concentration of 6.0 wt% for 120 seconds at 2500 rpm.
- An organic electroluminescent element was produced in the same manner as in Comparative Example 9 except that a coating-type hole transport layer having a film thickness of 198 nm was formed by spin coating.
- the organic electroluminescence device of the example has a leak occurrence rate of a level according to the case where a glass substrate by a conventional high-cost fusion method is used (Reference Examples 1-1 and 1-2).
- the charge injection / transport layer hole injection / transport layer
- Comparative Example 1-1, Comparative Example 1-2, Compared with Comparative Examples 2 and 3 the charge injection / transport layer
- the occurrence of leakage is suppressed. Note that some examples in Table 14 have a higher leak rate than the comparative examples in Table 15 (for example, Example 1-2 has a higher leak rate than Comparative Examples 8 to 10).
- the data in the table shows that the charge injection / transport layer (hole injection / transport layer) has almost the same thickness and the type of aromatic amine polymer contained in the charge injection / transport layer (hole injection / transport layer). Should be compared with each other (with or without crosslinking).
- the film thickness of the hole injecting and transporting layer is about 150 nm, but the aromatic amine polymer crosslinked in the hole injecting and transporting layer is used.
- Example 1-2 it can be seen that the occurrence of leakage is suppressed as compared with Comparative Example 6 in which the aromatic amine polymer crosslinked in the hole injecting and transporting layer is not used.
Abstract
Description
有機電界発光素子は、電極間の有機層に正負の電荷(キャリア)を注入し、このキャリアを再結合させることにより発光を得る素子である。
ガラス基材の材料及び製造方法としては、安価で大面積のガラス基材が得やすいことから、フロート法によるソーダライムガラス(以下、アルカリガラスと記載することがある)が一般的に用いられているが、有機電界発光素子の基材としては、フュージョン法による無アルカリガラスを用いることが一般的である。その理由は以下のとおりである。
フュージョン法とは、溶融した硝材を細長い樋状の湧き出し口へ導入し、その長手方向に沿う両側に溢れ出させて下へ流し落とし、流れ落ちた溶融ガラスを樋の下で再び合流させそのまま下へ落としながら除冷して板ガラスとするものである。
しかしながら、無アルカリガラスは、ソーダライムガラスに比べて不純物であるアルカリ金属を低減させているため製造コストが高く、また、フュージョン法は、フロート法に比べて生産性が低いことからやはり製造コストが高いという問題がある。
また、より安価なフロート法により製造したガラス基材を有機電界発光素子に用いることも試みられているが、その場合は、ガラス基材の表面性を改善するために、基材表面を研磨することが必要とされており、製造コストが高くなるという問題がある(特許文献3参照)。なお、特許文献3には、「STN-LCD用途のソーダライムガラス基板はセルギャップムラの抑制を目的として、ガラス基板のうねりを低減させる必要がある。そのため、ガラス表面の研磨を実施しているが、パッシブ型有機EL素子の用途に使用するためには、さらに微細なガラス基板の凹凸の制御を行う必要がある。」と記載されていることから、特許文献3に記載のガラス基板は、うねりが低減されたものと考えられる。また、特許文献3の実施例では、陽極上に真空蒸着法で各層を形成している。
即ち、第一の本願発明は、
ガラス基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子であって、
(1)該ガラス基材の該第1導電層側表面のうねり正接の最小値が4.00×10-6以上、又は該うねり正接の最大値が22×10-6以上であり、
(2)該電荷注入輸送層は湿式成膜法により形成された層であり、
(3)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(4)該電荷注入輸送層の膜厚が130~1000nmであり、
(5)該電荷注入層が、架橋された芳香族アミン重合体を含む、
有機電界発光素子、に存する。
第一の本願発明において、前記ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上であることが好ましい。
また、第一の本願発明において、前記ガラス基材が、Na2OおよびK2Oの少なくとも一方を1.0質量%以上含有することが好ましい。
また、第一の本願発明において、前記電荷注入輸送層の膜厚が130~500nmであることが好ましい。
さらに、第一の本願発明において、前記ガラス基材がフロート法により製造されたものであることが好ましく、未研磨のガラス基材であることがより好ましい。
さらにまた、第一の本願発明において、前記架橋された芳香族アミン重合体が、下記式(1)で表される部分構造を含むことが好ましい。
また、第一の本願発明において、前記架橋された芳香族アミン重合体が、下記架橋性基群Tから選ばれる架橋性基に由来する架橋構造を有することが好ましい。
<架橋性基群T>
即ち、第二の本願発明は、
基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子であって、
(1)該電荷注入輸送層は湿式成膜法により形成された層であり、
(2)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(3)該電荷注入輸送層の膜厚が130~1000nmであり、
(4)該電荷注入層が、架橋された芳香族アミン重合体を含む、
有機電界発光素子、に存する。
第二の本願発明において、前記基材がガラス基材であり、該ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上であることが好ましい。
また、第二の本願発明において、前記ガラス基材がフロート法により製造されたものであることが好ましく、前記ガラス基材が未研磨のガラス基材であることがより好ましい。
さらに、第二の本願発明において、前記電荷注入輸送層の膜厚が130~500nmであることが好ましい。
ガラス基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子の製造方法であって、
(1)該ガラス基材として、該1導電層側表面のうねり正接の最小値が4.00×10-6以上、又は該うねり正接の最大値が22×10-6以上であるガラス基材を、該うねり正接を有する面が該第1導電層側表面となるように用い、
(2)該電荷注入輸送層は湿式成膜法により形成され、
(3)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(4)該電荷注入層を、架橋性基を有する芳香族アミン重合体と溶媒とを含む組成物を湿式成膜法にて塗布、乾燥、架橋させることによって形成し、
(5)該電荷注入輸送層を130~1000nmの膜厚で形成する、
有機電界発光素子の製造方法、に存する。
第三の本願発明において、前記ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上であることが好ましい。
また、第三の本願発明において、前記ガラス基材として、Na2OおよびK2Oの少なくとも一方を1.0質量%以上含有するガラス基材を用いることが好ましい。
また、第三の本願発明において、前記電荷注入輸送層の膜厚が130~500nmであることが好ましい。
さらに、第三の本願発明において、前記ガラス基材として、フロート法により製造されたガラス基材を用いることが好ましく、フロート法により製造され、かつ、未研磨であるガラス基材を用いることがより好ましい。
基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子の製造方法であって、
(1)該電荷注入輸送層は湿式成膜法により形成され、
(2)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(3)該電荷注入輸送層の膜厚は130~1000nmであり、
(4)該電荷注入層を、架橋性基を有する芳香族アミン重合体と溶媒とを含む組成物を湿式成膜法にて塗布、乾燥、架橋させることによって形成する、
有機電界発光素子の製造方法、に存する。
第四の本願発明において、前記基材がガラス基材であり、該ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上であることが好ましい。
また、第四の本願発明において、前記ガラス基材として、フロート法により製造されたガラス基材を用いることが好ましく、フロート法により製造され、かつ、未研磨のガラス基材を用いることがより好ましい。
さらに、第四の本願発明において、前記電荷注入輸送層の膜厚が130~500nmであることが好ましい。
即ち、第五の本願発明は、
ガラス基材上に、少なくとも第1導電層と、湿式成膜法により形成された、電荷輸送材料を含有する電荷注入輸送層と、発光層と、第2導電層とをこの順に有する有機電界発光素子であって、
該ガラス基材がフロート法により製造され、
該第1導電層形成側の該ガラス基材表面が未研磨の状態であり、
該電荷注入輸送層の膜厚が、該第1導電層の膜厚の1.3倍以上である、有機電界発光素子、に存する。
即ち、第六の本願発明は、
ガラス基材上に、少なくとも第1導電層と、湿式成膜法により形成された、電荷輸送材料を含有する電荷注入輸送層と、発光層と、第2導電層とをこの順に有する有機電界発光素子であって、
該第1導電層形成側の該ガラス基材表面のうねり正接の最小値が4.20×10-6以上、又は該うねり正接の最大値が22×10-6以上であり、
該電荷注入輸送層の膜厚が、該第1導電層の膜厚の1.3倍以上である、有機電界発光素子、に存する。
尚、本発明において、質量で表わされる全ての百分率は、重量で表わされる百分率と同様である。
本明細書中では、有機電界発光素子を支持する基体について、第1導電層を含んで指示する場合は「基板」、第1導電層を含まずに指示する場合は「基材」と表記する。両方をまとめて指示する場合は、「基材等」と呼ぶこととする。また支持体の主要材料を特に指示する場合はそれぞれの用語の直前に材料表示を行う。例えば、主要材料がガラスである場合は、「ガラス基材」、「ガラス基板」、「ガラス基材等」となる。
従って、第一の本願発明は、電荷注入輸送層の膜厚が、130~1000nmであることをひとつの特徴とする。この膜厚がこの範囲であることにより、ガラス基材の平坦性が悪く、表面欠陥が多数存在する状態であった場合でも、電荷注入輸送層の平坦性が確保され、その結果、有機電界発光素子として機能しない領域の発生を抑制できることとなる。なお、厚みが厚いほど平坦性が確保できるが、発光材料からの発光の吸収を抑えるためには、厚みが1000nm以下である。
本発明の有機電界発光素子は、基材、好ましくはガラス基材上に、少なくとも、第1導電層と、湿式成膜法により形成された電荷注入輸送層と、発光層と、第2導電層とが積層された構造を有する。
以下に、本発明の有機電界発光素子の層構成の実施の形態の一例を、図1を参照して説明する。
図1は本発明の有機電界発光素子10の構造例を示す断面の模式図であり、図1において、1は基材、2は陽極、3は湿式成膜法により形成された正孔注入層、4は湿式成膜法により形成された正孔輸送層、5は発光層、6は正孔阻止層、7は電子輸送層、8は電子注入層、9は陰極を各々表す。
本発明の有機電界発光素子は、第1導電層(陽極)、電荷輸送材料を含有する電荷注入輸送層(湿式成膜法により形成された正孔注入層および湿式成膜法により形成された正孔輸送層に相当する)、発光層及び第2導電層(陰極)を必須の構成層とするが、必要に応じて、図1に示すように上記必須の層の間に他の機能層を有していてもよいし、上記必須の層を2層以上の多層構造としてもよい。具体的には、湿式成膜法により形成された正孔輸送層4と発光層5の間に、蒸着法により形成された正孔輸送層を設けてもよい。この場合、蒸着法により形成された正孔輸送層は本願における電荷注入輸送層には相当しない。また、正孔注入層3のみを湿式成膜法により形成し、正孔輸送層4を、真空蒸着法等の非湿式成膜法により形成した場合は、本発明の電荷注入輸送層は正孔注入層3のみとみなす。
基材1は、有機電界発光素子の支持体となるものである。本発明における有機電界発光素子の基材としては、ガラス板、金属板や樹脂を用いることができる。好ましくは光透過性のガラス板、透明樹脂シートである。さらに、ガラス板としては、従来用いることが困難であった、特定の範囲のうねり正接値を有するガラス基材を用いることができる(本願第一の発明の特徴のひとつ)。
特定の範囲のうねり正接値を有するガラス基材を得るための方法としては、以下の方法が挙げられる。
本発明における基材がガラス基材である場合、ガラス基材1は、フロート法により製造されたものである。フロート法とは、SiO2等の硝材を融解炉の中で均一に熔かし、引き出し口から連続的にガラスを流し出して、錫を熔かしたプール炉の上をゆっくり滑らせて徐々に冷却し取り出すという方法である。
また、本発明のガラス基材1は、フロート法により製造された後、第1導電層等を形成する側の表面に対して、何ら機械的または化学的な研磨を施されていない、未研磨の状態であることが必要である。
ガラス基材の成分に関しては、組成分析の手法を用いて決定することが好ましい。例えば半定量分析、定量分析のいずれも採用することが可能であるが、好ましくは定量分析による方法が正確性から採用されるべきである。
フロート法で製造されたガラス基材は、フュージョン法で製造されたガラス基材に比べ、ガラス基材表面のうねりが大きい傾向にある。また、フロート法で作製されたガラス基材を研磨することによっても、ガラス基材表面のうねりは低下する。従って、本願発明のガラス基材またはガラス基板は、表面のうねりの大きさを示す指標の値が、特定の数値以上であると言える。
うねり正接の最小値は、4.00×10-6以上が好ましく、4.02×10-6以上がより好ましく、4.20×10-6以上が更に好ましい。うねり正接の最大値は、通常22×10-6以上であり、28×10-6以上が好ましく、33×10-6以上がより好ましい。
また、うねり正接の最小値が上記値以上であるか、または、うねり正接の最大値が上記値以上であることが好ましく、うねり正接の最小値が上記値以上であり、かつ、うねり正接の最大値が上記値以上であることがさらに好ましい。
上記において、うねり正接の最小値の上限は、通常9.0×10-6、好ましくは8.5×10-6、うねり正接の最大値の上限は、通常100×10-6、好ましくは90×10-6、より好ましく88×10-6、更に好ましくは70×10-6、特に好ましくは、60×10-6、最も好ましくは50×10-6である。
尚、上記の好ましい範囲は、フロート法による未研磨のガラスのうねり正接の標準的なものであり、安価なガラスでありながら、後述の電荷注入層の成分やその膜厚のコントロールによって、ショートやリークという素子欠陥の発生の抑制に好適なものである。
上記の通り、本発明は、ガラス基材またはガラス基板のうねりの大きさを特徴のひとつとするが、かかるガラス基材またはガラス基板自体は、市販のガラス、或いは、公知の方法で製造されたガラスについて、そのうねりを測定して、これを満足するものを用いればよく、通常、フロート法により製造され、好ましくは未研磨のガラスから選択される。
なお、ガラス基板の第1導電層は、通常、スパッタリング法、真空蒸着法などの気相成長法によって形成されるため、ガラス基材の表面性状にほぼ倣うように該層が形成される。従って、ガラス基材上に第1導電層を形成したガラス基板のうねり正接の値は、ガラス基材の場合とほぼ同一である。気相成長法以外の方法によって第1導電層を形成した場合の第1導電層表面のうねり正接の値は、元々の基材表面のうねり正接の値と異なることがあるので、基材表面のうねり正接を評価すべきである。
表面のうねりに関する定義は、「JIS B0601:2001-製品の幾何特性仕様(GPS)-表面性状:輪郭曲線方式-用語,定義及び表面性状パラメータ」を基本的には用いる。これによると、うねりとは「3.1.7うねり曲線(waviness profile)」に記載されている内容から算出される表面性状パラメータとされている。うねり曲線の中でも、こうしたデータ処理によって得られる曲線を特に、ろ波うねり曲線と呼ぶ。カットオフ値及び輪郭曲線フィルタについては、JIS B0632の2.6(輪郭曲線の通過帯域)及び3.2(振幅伝達特性)に記載されている。以下、具体的にうねり正接の測定方法を述べる。
ここで注意しなければならないのは、元々のガラス基材等の形状およびそこからの偏差、ガラス基材等のソリ、変形などがある場合は、注意深くうねりと区別して、データから排除しておかなければならないことである。こうしたうねりと区別すべき変化は、総称して「形状偏差曲線」という輪郭曲線の1種に繰り込まれるが、λf輪郭曲線フィルタをかける前に最小二乗法によって注意深く除去されなければならない。
こうして得られたろ波うねり曲線からうねり性状パラメータとして次のようなパラメータを定義する。
平均線は、低域(ローパス)用λf輪郭曲線フィルタによって遮断される長波長成分を表す曲線(JIS B0632の3.2 参照)である。X軸とも表記する。
山、および谷の定義は、平均線からどれだけ高いか、あるいは低いかで決定するが、一般に、山及び谷と判断する最小高さは、うねり輪郭曲線の最大高さ(Wz)のパーセント値によって規制する。本発明ではWzの10%以上であれば、山、あるいは谷と判別する。
(3)輪郭曲線要素の長さ(profile element width:Xs)
輪郭曲線要素の長さは、輪郭曲線要素によって切り取られたX軸の線分の長さである。一般に、横方向の最小長さは,基準長さlwのパーセント値によって規制する。本発明ではlwの10%以上であれば、Xsとして測定値を与える。
抽出したうねり輪郭曲線要素における山と谷の差分値
(5)Wz-min
うねり高さの最小値
(6)Wz
うねり高さの最大値
(7)Xs-min
抽出したうねり輪郭曲線要素の長さの最小値
(8)Xs-max
抽出したうねり輪郭曲線要素の長さの最大値
うねり正接 ={(山高さ)-(谷深さ)}/Xs
うねり正接の最小値 = Wz-min/Xs-max
うねり正接の最大値 = Wz/Xs-min
ここで、うねり正接は、1つのうねり輪郭曲線要素で測定された値の組み合わせから算出されることに限定されるものではなく、測定値として同一のサンプルから得られたものであれば、どのように可能な組み合わせでも値を算出して求められる。
なお、本発明に用いられるガラス基材またはガラス基板は、例えば、補助電極のような有機電界発光素子を区画する隔壁を設けた場合には、上述の通り従来のガラス基材等に比べうねりが大きいためにガラス基材等と隔壁部分との接触面積が増すことから、隔壁の付着強度が高くなるという効果も期待できる。
基材上に陽極を設ける場合、陽極は本願における第1導電層である。
陽極2は、発光層5側の層への正孔注入の役割を果たす電極である。
陽極2には、有機電界発光素子全面に十分な電圧を印加するために、一定以上の電気伝導度が要求される。また、通常、有機電界発光素子から発光された光を基材側から取り出すため、一定以上の透過率が要求される。
この陽極2は、通常、アルミニウム、金、銀、ニッケル、パラジウム、白金等の金属、インジウム及び/又はスズの酸化物等の金属酸化物、ヨウ化銅等のハロゲン化金属、カーボンブラック、或いは、ポリ(3-メチルチオフェン)、ポリピロール、ポリアニリン等の導電性高分子等により構成されるが、上述の要求性能を満たすためには、インジウム及び/又はスズの酸化物等の金属酸化物(以下、ITOと記載)が最も好適な材料として用いられる。
また、ITOなどの表面に、有機EL層への正孔注入性を向上させる目的で、薄い導電性無機膜を形成してもよい。本願においては薄い導電性無機膜も第1導電層に含まれるとみなす。薄い導電性無機膜としては、例えば、光透過性の金属薄膜若しくは光半透過性の金属薄膜、または、酸化モリブデン若しくは酸化バナジウムなどの金属酸化物膜が挙げられる。
陽極2の厚みは、必要とする透明性や電気伝導度などに応じて適宜選択すればよい。透明性が必要とされる場合は、可視光の透過率を、通常60%以上、好ましくは80%以上とすることが好ましい。この場合、陽極2の厚みは、通常5nm以上、好ましくは10nm以上である。また、この場合、陽極2の厚みは、通常1000nm以下、好ましくは500nm以下程度である。
前述の通り、本発明のガラス基材には表面欠陥が多く存在する。ガラス基材上の表面欠陥とは、ガラス基材の製造工程で生じる欠陥であり、以後は「ガラス欠陥」と呼ぶ。さらに、ガラス欠陥としては、「ガラス内部欠陥」および「ガラス表面欠陥」に分別され、それぞれのガラス欠陥には様々なモード(発生原因や形態・様態によって分類されるカテゴリー)がある。
ガラス欠陥を低減もしくは除去する理由は、こうしたガラス欠陥の多いガラス基材に第1導電層を形成すると、局所的に第1導電層が形成されずにピンホールとなったり、ドリップやキズでできた突起上に第1導電層が形成されることにより、その後に形成する発光層等の有機膜が局所的に薄くなったり、あるいは形成されないといったことが生じ、第1導電層と第2導電層との距離が接近、あるいは直接接触するといった状況を引き起こし、電気的特性としては、ショートあるいはリークという素子欠陥につながるからである。
本発明の表面欠陥の密度については、予め多数のガラス基板についてその表面欠陥を観察・分類し、表面欠陥のモードを設定した上で、表面欠陥の計測が必要なガラス基板については、7mm×10.5mm角に第1導電層をパターニングし、それを4面、光学顕微鏡による目視測定を実施し、計測面積で規格化して表面欠陥の密度を算出し、平均値を求めた。目視測定の設定条件としては、対物レンズ倍率=20倍、接眼レンズ倍率=10倍とした。この設定においては、最小サイズの表面欠陥が接眼視野内において1mm程度の大きさに拡大される。観察は主として明視野を用い、適宜、暗視野・微分干渉観察を使い分けた。この使い分けは表面欠陥以外の付着物と表面欠陥とを区別するためである。
正孔注入輸送層は本発明における電荷注入輸送層である。
本発明においては、陽極2と発光層5の間に、正孔輸送材料を含有する正孔注入輸送層11を、湿式成膜法により形成する。正孔注入輸送層11は、陽極2から注入された正孔を発光層5に輸送する働きを有しており、1層で形成してもよいが、図1に示すように、湿式成膜法により形成された正孔注入層3と湿式成膜法により形成された正孔輸送層4の2層構造とするのが好ましい。正孔注入層3は、本発明における電荷注入層であり、本発明における第1導電層である陽極に接している。
本発明の基材に第1導電層を形成した状態においては、前述の通り表面欠陥の密度が大きく、このままではショートあるいはリークという電気的素子欠陥を引き起こす可能性が極めて高い。
これは、湿式成膜という方法を採用しなければ得られず、真空蒸着法その他の乾式成膜法では決して得られなかった結果である。
第四及び第五の本願発明では、電荷注入輸送層の膜厚は、該第1導電層の膜厚の1.3倍以上であるが、これは、1導電層の膜厚が大きいほど、第1導電層の剥落や再付着による凹凸の段差も大きくなり、段差を被覆するための電荷注入輸送層の膜厚も大きくする必要があるためと推察される。電荷注入輸送層の膜厚は、第1導電層の膜厚の1.3倍以上であり、好ましくは1.5倍以上、更に好ましくは1.8倍以上である。電荷注入輸送層の膜厚の上限については、発光材料からの発光の吸収を抑えるために、6.0倍以下、好ましくは5.0倍以下である。
ではなぜ見出し得なかったかという理由について述べる。単独で表面欠陥が存在している状況では、たとえリークしていても、極めて微小である場合が多く、リークとして認知できない、あるいはリークが存在しない、と判定されることが多かったためと推測される。しかしながら、表面欠陥の密度が大きいガラス基板の場合、リークとして判定される又は判定されない、ということが、表面欠陥の密度が低いガラス基板と比べて、わずかな電荷注入輸送層の膜厚ズレであっても、表面欠陥の密度が高い分増幅されるので、結果として敏感に判定されるようになったと推測される。すなわち、表面欠陥の密度が高いことが、リーク認知あるいはリーク判定閾値上昇の大きな要因と考えられる。
正孔注入層3及び正孔輸送層4に用いる材料については、公知の正孔輸送性を有する材料を適宜用いればよい。但し、第一及び第二の本願発明においては、後述の通り、架橋された芳香族アミン重合体を含むことを必須とし、第三及び第四の本発明においては、後述の通り、架橋性基を有する芳香族アミン重合体を含むことを必須とする。
本発明の電荷注入層である正孔注入層3に用いる材料は、以下の通りであることが好ましい。
正孔注入層3に用いる材料は、陽極から正孔注入層への電荷注入障壁の観点から、4.5eV~6.0eVのイオン化ポテンシャルを有する化合物が好ましく、非晶質性及び可視光透過性の点から、芳香族アミン化合物が好ましく、芳香族三級アミン化合物が特に好ましい。ここで、芳香族三級アミン化合物とは、芳香族三級アミン構造を有する化合物である。芳香族三級アミン化合物としては、重量平均分子量が1,000以上1,000,000以下の高分子化合物(繰り返し単位が連なる重合型化合物)を用いるのが好ましく、架橋性基を有している。正孔注入層の上にさらに湿式成膜法で積層成膜する場合には架橋性基を有することが好ましい。また、正孔注入層には、正孔輸送性化合物の酸化により、正孔注入層の導電率を向上させることができるため、電子受容性化合物を含有していることが好ましい。電子受容性化合物の具体例としては日本国特開2006-233162号公報等に記載のものが、架橋性基を有する芳香族三級アミン化合物の具体例としては日本国特開2009-287000号公報等に記載のものが挙げられる。
正孔輸送層4に用いる材料は、以下の通りであることが好ましい。
正孔輸送層4に用いる材料は、正孔輸送性を有する材料であり、非晶質性及び可視光透過性の点から、芳香族アミン化合物が好ましく、芳香族三級アミン化合物が特に好ましい。ここで、芳香族三級アミン化合物とは、芳香族三級アミン構造を有する化合物である。芳香族三級アミン化合物としては、重量平均分子量が1,000以上1,000,000以下の高分子化合物(繰り返し単位が連なる重合型化合物)を用いるのが好ましく、架橋性基を有していてもよい。正孔輸送層の上にさらに湿式成膜法で積層成膜する場合には架橋性基を有することが好ましい。具体例としては、日本国特開2009-287000号公報等に記載のものが挙げられる。正孔輸送層4が湿式成膜法により形成されている場合は、本発明における電荷注入輸送層に含まれることとなる。
上記のうち、第一及び第二の本願発明は、電荷注入輸送層が、架橋された芳香族アミン重合体を含み、第三及び第四の本発明は、架橋性基を有する芳香族アミン重合体を含む組成物を湿式成膜法にて塗布、乾燥、架橋させることによって電荷注入輸送層を形成することを特徴する。電荷注入輸送層に含まれる架橋された芳香族アミン重合体については後述するが、第一乃至第四の本発明においては、電荷注入輸送層が、架橋された芳香族アミン重合体を含むことによって、リークが防止される。その理由は、以下の通りと考えられる。
しかも、架橋させた膜なので、さらにその上に塗布する場合においても、塗布組成物に含まれる溶媒によって溶出することが極めて起きにくくなる。このことによって、さらに第2層目を塗布した際、第1層によって覆われていた突起や窪みの鋭く尖った角が露出してしまって第2層を塗布した効果が無くなる、ということが防止できることとなる。
臨界温度以下において、絶縁破壊電圧は固体試料の厚みに比例することが知られている。即ち、破壊電圧を試料厚みで割った絶縁破壊電界強度(或いは単に破壊強度)が存在する。このことは前述した絶縁破壊の生起するメカニズムに一致する。
ここで、同じ電圧を同じ厚みの固体試料に印加した場合、固体の比誘電率が1に近いほど固体内の電界強度が大きい(固体内の電界強度はその誘電率に反比例する)という事実がある。即ち、比誘電率が1よりも大きくなればなるほど、固体内の電界強度は絶縁破壊電界強度より低くなる。
ここで、古典的なClausius-Mossottiの式を想起すればわかるように、比誘電率は分極率と密度の積に依存するため、比誘電率を増大させるには分極率が同じ(固体の構成原子・分子が同じ)であるならば、密度の増大が必要である。
絶縁破壊は、膜中で局所的に発生する。膜厚が薄いほど、膜の両面にまたがる絶縁破壊によってショートする可能性が高まるが、膜厚が厚い場合はショートするほどの絶縁破壊は起きにくい。通常、100nm以上の膜厚を有する場合、絶縁破壊によるショートは起きにくいが、膜中の局所的な絶縁破壊によって局所的に大きな電流が流れる。膜の両面から電圧を印加して電流測定した場合、電流量の増大としてリークを検知することができる。前述のとおり、局所的な絶縁破壊によってリークは発生するので、絶縁破壊されにくいほどリークしにくい。従って、膜厚が同じであれば、架橋されている方がリークしにくく、好ましい。
通常、電荷輸送層の膜厚はせいぜい100nm程度のオーダーであるため、例えば5倍の500nmにした場合、印加電圧を5倍にしないと電界強度は同程度にならないが、実際の有機電界発光素子においては、通常、電圧は数十%増やせば必要な輝度を得ることができる。従って、電荷輸送層の膜厚が比較的厚い場合、架橋されていない膜であっても絶縁破壊されにくくなり、その結果、リーク発生確率は0にはならないながらも低い値となる。しかしながら、膜の密度は変わらないので、架橋されている膜の方がリークしにくい。従って、膜厚が比較的厚い場合であっても架橋されている膜の方が架橋していない膜よりもリークしにくく好ましい。
さらに、局所的な電界強度は基板の表面形状の影響を受けやすいと考えられるため、基板と接する層が架橋されていることが、基板と接する層が絶縁破壊されにくく、すなわちリークしにくく好ましい。基板と接する層は通常、電荷注入層であるため、電荷注入層が架橋されていることが好ましい。
また、膜が均一であり、かつ、電界強度が同じであると仮定した場合、膜厚が厚いほど絶縁破壊が発生する可能性のある箇所が多いとみなせる。従って、電荷注入輸送層を形成する膜が複数の異なる膜からなる場合は、より膜厚が厚いほど絶縁破壊が多く発生すると考えられるため、最も厚い膜が架橋されていることが好ましい。
[芳香族アミン重合体]
架橋された芳香族アミン重合体は、架橋性基を有する芳香族アミン重合体を架橋させることによって得られる。
以下に、架橋性基を有する芳香族アミン重合体について説明する。
本発明における架橋性基を有する芳香族アミン重合体は、下記式(1)で表される部分構造を含む。
芳香族炭化水素環基としては、例えば、1個又は2個の遊離原子価を有する、ベンゼン環、ナフタレン環、フェナントレン環、アントラセン環、トリフェニレン環、クリセン環、ナフタセン環、ペリレン環、コロネン環、アセナフテン環、フルオランテン環、フルオレン環等の5又は6員環の単環又は2~5縮合環、および、これらの環が複数個直接結合している環等が挙げられる。ここで、本発明において、遊離原子価とは、有機化学・生化学命名法(上)(改定第2版、南江堂、1992年発行)に記載のとおり、他の遊離原子価と結合を形成できるものを言う。すなわち、例えば、「1個の遊離原子価を有するベンゼン環」はフェニル基のことを言い、「2個の遊離原子価を有するベンゼン環」はフェニレン基のことを言う。
芳香族アミン重合体が正孔注入層を形成する場合は、第1導電層からの電荷注入性及び正孔注入層内での電荷輸送性に優れるため、Araにおいては特に、1個又は2個の遊離原子価を有する、ベンゼン環、ビフェニル、ターフェニルが最も好ましい。
炭素数3~20の(ヘテロ)アリールオキシ基としては、フェノキシ基、1-ナフチルオキシ基、9-アントラニルオキシ基等のアリールオキシ基及び2-チエニルオキシ基等のヘテロアリールオキシ基を有する置換基等が挙げられる。
炭素数3~20の(ヘテロ)アリールチオ基としては、フェニルチオ基、1-ナフチルチオ基、9-アントラニルチオ基等のアリールチオ基及び2-チエニルチオ基等のヘテロアリールチオ基等が挙げられる。
本発明における芳香族アミン重合体としては、下記式(11)、(12)、(13)又は(14)で表される繰り返し単位を有する重合体がさらに好ましい。
式(M1-1)~式(M1-3)で表される単量体は、各々独立に、1種類、又は、2種類以上用いてよく、10種類以下であることが好ましい。
なお、下記式(12)において、左辺上段は、ハロゲン化合物だけのホモカップリング反応(Ullmann反応、Yamamoto反応など)、左辺下段は、ハロゲン化合物と有機金属などとのクロスカップリング反応(Suzuki-Miyaura反応、Negishi反応、Migita-Kosugi-Stille反応など)を示す。
式(M2-2)中、Gは、Negishi反応であれば、BrZn-等の置換基を有する亜鉛原子、Migita-Kosugi-Stile反応であれば、(CH3)3Sn-等の置換基を有するスズ原子、Suzuki-Miyaura反応であれば、(RO)2B-(Rは水素原子又は互いに結合して環を形成してもよいアルキル基)等の置換基を有するホウ素原子を示す。
なお、式(12)、式(M2-1)、式(M2-2)中において、Ar1~Ar3、Z、a、b、X1が2以上存在する場合、各々異なっていてもよい。
式(13)、式(M3-2)中、Q1は、酸素原子、又は硫黄原子を表す。
なお、式(13)、式(M3-1)、式(M3-2)中において、Ar1~Ar3、Z、a、b、Q1、X1が2以上存在する場合、各々異なっていてもよい。
式(14)、式(M4-1)、式(M4-2)中、Q2はカルボニル基、又はスルホニル基を表し、Q3は、酸素原子、硫黄原子、又は-NR5-基(R5は、水素原子、置換基を有していてもよいアルキル基、前述と同義の芳香族炭化水素環基または芳香族複素環基を表す。)を表し、X2はハロゲン原子を表す。
なお、式(14)、式(M4-1)、式(M4-2)中において、Ar1~Ar3、Z、a、b、Q2、Q3が2以上存在する場合、各々異なっていてもよい。
第一及び第二の本発明は、電荷注入層が、架橋された芳香族アミン重合体を含む。従って、この場合には、芳香族アミン重合体は、架橋性基を有している。ここで、架橋性基とは、熱及び活性エネルギー線のうちのいずれか1つの照射により近傍に位置するほかの分子の同一又は異なる基と反応して、新規な化学結合を生成する基のことをいう。
芳香族アミン重合体が架橋性基を有することで、塗布後、これらの架橋性基によって芳香族アミン重合体が架橋される。また、芳香族アミン重合体が架橋されることによって不溶化し、この芳香族アミン重合体の上にさらに機能性薄膜を塗布により積層することができ、好ましい。
架橋性基としては、結合のしやすさから、下記<架橋性基群T>から選ばれ、この場合、本発明における架橋された芳香族アミン重合体は、該架橋性基群Tから選ばれる架橋性基に由来する架橋構造を有することとなる。
<架橋性基群T>
架橋性基としてはエポキシ基、オキセタン基などの環状エーテル基、ビニルエーテル基などのカチオン重合性基が、反応性が高く有機溶剤に対する架橋が容易な点で好ましい。中でも、カチオン重合の速度を制御しやすい点でオキセタン基が特に好ましく、カチオン重合の際に素子の劣化をまねくおそれのあるヒドロキシル基が生成しにくい点でビニルエーテル基が好ましい。
本発明における芳香族アミン重合体の分子内において、架橋性基は、(a)分子内の芳香族炭化水素基又は芳香族複素環基に直接結合していてもよく、(b)-O-基を介して芳香族炭化水素基又は芳香族複素環基に結合していてもよく、更には、(c)置換基を有していてもよい-CH2-基が1ヶ又は複数個連結してなる基、又は、これらが-O-基又は-C(=O)-基と連結して形成される2価の基を介して、芳香族炭化水素基又は芳香族複素環基に結合してもよい。なお、置換基を有していてもよい-CH2-基が1ヶ又は複数個連結している場合、2価の連結基の総炭素数は、1~30、好ましくは、1~20である。
これら2価の基を介する架橋性基、すなわち、架橋性基を含む基の具体例は以下の<架橋性基を含む基群T’>に示す通りであるが、本発明はこれらに限定されるものではない。
<架橋性基を含む基群T’>
なお、式(2)中にAr24およびAr25が複数ある場合、これらは互いに同一であってもよく、異なっていてもよい。)
Ar21、Ar22及びAr24に用いることのできる置換基を有していてもよい芳香族炭化水素環基、又は置換基を有していてもよい芳香族複素環基は、前述の式(1)におけるAraで表される構造と同じである。Ar23、Ar25に用いることのできる置換基を有していてもよい芳香族炭化水素環基、又は置換基を有していてもよい芳香族複素環基は、前述の式(1)におけるArbで表される構造と同じである。
T2は上述の架橋性基群T、及び、該架橋性基群Tの基が前記(b)又は(c)の2価の基に連結してなる基の中から選ばれる。中でも、T2は上述の架橋性基群T、及び、架橋性基を含む基群T’の中から選ばれるのが好ましい。また、T2は特に、下記式(3)で表される基を含む基が好ましい。
また、本発明における芳香族アミン重合体は、下記式(4)からなる部分構造を含んでいてもよい。
nは0~3の整数を表し、
Ar1は、置換基を有していてもよい芳香族炭化水素環基、又は置換基を有していてもよい芳香族複素環基を表し、
Ar2は、直接結合、置換基を有していてもよい芳香族炭化水素環基、又は置換基を有していてもよい芳香族複素環基を表し、
Ar3~Ar5は、各々独立に、置換基を有していてもよい芳香族炭化水素環基又は置換基を有していてもよい芳香族複素環基を表す。
Tは架橋性基を含む基を表す。
なお、式(4)中にAr4およびAr5が複数ある場合、これらは互いに同一であってもよく、異なっていてもよい。)
Ar1、Ar2及びAr4に用いることのできる置換基を有していてもよい芳香族炭化水素基、又は置換基を有していてもよい芳香族複素環基は、前述の式(1)におけるAraで表される構造と同じである。Ar3、Ar5に用いることのできる置換基を有していてもよい芳香族炭化水素基、又は置換基を有していてもよい芳香族複素環基は、前述の式(1)におけるArbで表される構造と同じである。
Tとしては前記式(2)におけるT2と同様の基が挙げられ、上述の架橋性基群T及び架橋性基を含む基群T’の中から選ばれるのが好ましい。また、Tは特に、前記式(3)で表される基を含む基が好ましい。
R8及びR9は、互いに結合して環を形成してもよい。
pは、1~5の整数を示す。
なお、式(5)中にAr6~Ar8、R8及びR9が複数ある場合、これらは互いに同一であってもよく、異なっていてもよい。)
R11は、置換基を有していてもよい炭素数1~12のアルキル基又は置換基を有していてもよい炭素数1~12のアルコキシ基を示し、R12~R17は、各々独立に、水素原子、置換基を有していてもよい炭素数1~12のアルキル基、置換基を有していてもよい炭素数1~12のアルコキシ基、置換基を有してもよい炭素数6~25の芳香族炭化水素環基又は置換基を有していてもよい炭素数3~20の芳香族複素環基を示す。
R12及びR13、R14及びR15並びにR16及びR17は、夫々互いに結合して環を形成してもよい。
l、m及びnは各々独立に0~2の整数を示す。
なお、式(6)中にAr31~Ar35またはR12~R17が複数ある場合、これらは互いに同一であってもよく、異なっていてもよい。)
Ar32、Ar8に用いることのできる置換基を有していてもよい芳香族炭化水素基は、前述のArbに用いることのできる芳香族炭化水素基と同じである。
R12~R17及び、R8、R9は、各々独立して、水素原子、置換基を有していてもよいアルキル基、置換基を有していてもよいアルコキシ基、又は置換基を有していてもよい芳香族基を示し、互いに結合して環を形成してもよい。R11、R12~R17及び、R8、R9は、溶解性の点から、炭素数1~12のアルキル基及び炭素数1~12のアルコキシ基が好ましく、炭素数1~12のアルキル基がより好ましい。
Ar31、Ar33、Ar34、Ar35、Ar6、Ar7、R12~R17、R8、R9が有していてもよい置換基は、前述のAraまたはArbで表される芳香族炭化水素基又は芳香族複素環基が有していてもよい置換基または、前記架橋性基が挙げられる。
本発明における芳香族アミン重合体は、部分構造として式(1)、(11)、(12)、(13)、(14)、(2)、(4)、(5)、(6)、2価のベンゼン環、および、2価の5又は6員環の単環又は2~5縮合環である芳香族炭化水素の中から選ばれる部分構造からなる重合体であることが好ましい。さらにその中でも、本発明における芳香族アミン重合体は、部分構造として式(1)、(11)、(12)、(13)、(14)、(2)、(4)、(5)、(6)、2価のベンゼン環、および、2価の6員環の2~5縮合環である芳香族炭化水素の中から選ばれる部分構造からなる重合体であることが好ましい。
本発明における芳香族アミン重合体の重量平均分子量(Mw)は、通常3,000,000以下、好ましくは1,000,000以下、より好ましくは500,000以下であり、また通常2,000以上、好ましくは3,000以上、より好ましくは5,000以上である。
通常、この重量平均分子量はSEC(サイズ排除クロマトグラフィー)測定により決定される。SEC測定では高分子量成分ほど溶出時間が短く、低分子量成分ほど溶出時間が長くなるが、分子量既知のポリスチレン(標準試料)の溶出時間から算出した校正曲線を用いて、サンプルの溶出時間を分子量に換算することによって、重量平均分子量が算出される。
以下、上述した芳香族アミン重合体を含む電荷注入輸送層の形成方法について説明する。なお、本発明が、図1の態様の場合、電荷注入輸送層が正孔注入輸送層であるので、以下、電荷注入輸送層が正孔注入輸送層である場合を例に説明する。
正孔注入輸送層の形成に用いられる正孔注入輸送層形成用組成物は、前述した架橋性基を有する芳香族アミン重合体及び必要に応じてその他の成分を、溶解又は分散可能な溶媒と混合することにより調製される。
エステル系溶媒としては、例えば、酢酸エチル、酢酸n-ブチル、乳酸エチル、乳酸n-ブチル等の脂肪族エステル及び酢酸フェニル、プロピオン酸フェニル、安息香酸メチル、安息香酸エチル、安息香酸プロピル及び安息香酸n-ブチル等の芳香族エステル等が挙げられる。
エーテル系溶媒としては、例えば、エチレングリコールジメチルエーテル、エチレングリコールジエチルエーテル、プロピレングリコール-1-モノメチルエーテルアセタート(PGMEA)等の脂肪族エーテル、1,2-ジメトキシベンゼン、1,3-ジメトキシベンゼン、アニソール、フェネトール、2-メトキシトルエン、3-メトキシトルエン、4-メトキシトルエン、2,3-ジメチルアニソール、2,4-ジメチルアニソール等の芳香族エーテル等のエーテル系溶媒などが挙げられる。
ケトン系溶媒としては、例えば、シクロヘキサノン、シクロオクタノン、フェンコン等の脂環族ケトン、メチルエチルケトン、ジブチルケトン等の脂肪族ケトン等が挙げられる。
アルコール系溶媒としては、例えば、シクロヘキサノール、シクロオクタノール等の脂環族アルコール、ブタノール、ヘキサノール等の脂肪族アルコール等が挙げられる。
含ハロゲン有機溶媒としては、1,2-ジクロロエタン、クロロベンゼン及びo-ジクロロベンゼン等が挙げられる。
アミド系溶媒としては、例えば、N,N-ジメチルホルムアミド及びN,N-ジメチルアセトアミド等が挙げられる。
また、これらの他、ジメチルスルホキシド等も用いることができる。
これらの溶媒は、1種類を単独で用いても、2種類以上を任意の組合せ及び比率で併用してもよい。
また、より均一な膜を得るためには、成膜直後の液膜から溶媒が適当な速度で蒸発することが好ましい。このため、溶媒の沸点は、通常80℃以上、好ましくは100℃以上、より好ましくは120℃以上であることがよい。また、溶媒の沸点は、通常270℃以下、好ましくは250℃以下、より好ましくは沸点230℃以下であることがよい。溶媒の沸点が低すぎると、乾燥速度が速すぎ、膜質が悪化する可能性がある。また、溶媒の沸点が高すぎると乾燥工程の温度を高くする必要があり、他の層や基板に悪影響を与える可能性がある。
正孔注入輸送層形成用組成物に含まれる芳香族アミン重合体の量は、該組成物の粘度が高くなる点では多い方が好ましいが、一方で、溶解性の点では少ない方が好ましい。そこで、具体的には、正孔注入輸送層形成用組成物に含まれる芳香族アミン重合体の量は、通常0.01質量%以上であり、0.1質量%以上であることが好ましく、0.5質量%以上であることが更に好ましく、また、一方、通常50質量%以下であり、40質量%以下であることが好ましく、20質量%以下であることがさらに好ましい。尚、正孔注入輸送層形成用組成物には、芳香族アミン重合体が2種以上含まれていてもよく、その場合は2種以上の合計が上記範囲となることが好ましい。
本発明の正孔注入輸送層11は、湿式成膜法により形成される。ここで、湿式成膜法とは、材料の塗布方法として、例えば、スピンコート法、ディップコート法、ダイコート法、バーコート法、ブレードコート法、ロールコート法、スプレーコート法、キャピラリーコート法、インクジェット法、ノズルプリンティング法、スクリーン印刷法、グラビア印刷法、フレキソ印刷法等の湿式で成膜させる方法を採用し、この塗布膜を乾燥させて膜形成を行う方法をいう。これらの成膜方法の中でも、スピンコート法、スプレーコート法、インクジェット法、ノズルプリンティング法などが好ましい。
本発明の正孔注入輸送層11は、上述の通り、湿式成膜法により形成される。但し、正孔注入輸送層形成用組成物が架橋性基を有する芳香族アミン重合体を有し、正孔注入輸送層(電荷注入輸送層)が架橋された芳香族アミン重合体を有する場合には、正孔注入輸送層形成用組成物被膜に含まれる架橋性基を有する芳香族アミン重合体を架橋させる工程を有する。正孔注入輸送層形成用組成物被膜と芳香族アミン重合体を架橋させる工程は2つの工程に分かれていてもよいし、同一行程であってもよい。
光などの活性エネルギー照射による場合には、赤外線での加熱が特に好ましい。赤外線加熱する場合には、ハロゲンヒーターやセラミックコートしたハロゲンヒーター、セラミックヒーター等が使用できる。ハロゲンヒーターとしては、例えば、ウシオ電機社製(UH-USC、UH-USD、UH-MA1、UH-USF、UH-USP、UH-USPN、およびこれらをセラミックコート(ブラックコート)したハロゲンヒーター)、ヘレウス社製等が挙げられる。遠赤外線ヒーターとしては、例えば、AMK社製(遠赤外線パネル型クリーンヒーター)がある。
赤外線の加熱に際し、基板の赤外線透過は、2000nm~3300nmの波長範囲に極小値を持つことが好ましい。また、赤外線透過率について、その上限値は、通常、95%以下、好ましくは90%以下、より好ましくは85%以下、さらに好ましくは80%以下、特に好ましくは75%以下である。また下限値については、通常、5%以上、好ましくは10%以上、より好ましくは20%以上、さらに好ましくは25%以上である。
また、赤外線ヒーターのピーク波長については、その下限値は、通常0.8μm以上、好ましくは0.9μm以上、より好ましくは1μm以上、特に好ましくは1.1μm以上である。またその上限値は、25μm以下、好ましくは10μm以下、より好ましくは5μm以下、特に好ましくは3μm以下である。
以下に、基板の赤外線透過率の極小値における波長と赤外線ヒーターのピーク波長の積(α)を、発明を特定するためのパラメータとして用いた理由を以下に述べる。
上記正孔注入輸送層形成用組成物によって形成される層が陽極上に形成される場合、陽極に接する層は正孔注入層として機能する。この場合、上記正孔注入輸送層形成用組成物は、電子受容性化合物を含むことが好ましい。
<電子受容性化合物>
正孔注入層には、正孔輸送性化合物の酸化により、正孔注入層の導電率を向上させることができるため、電子受容性化合物を含有していることが好ましい。
電子受容性化合物としては、酸化力を有し、上述の正孔輸送性化合物から一電子受容する能力を有する化合物が好ましく、具体的には、電子親和力が4eV以上である化合物が好ましく、電子親和力が5eV以上である化合物が更に好ましい。
電子受容性化合物として好適な有機基の置換したオニウム塩、シアノ化合物又は芳香族ホウ素化合物の具体例としては、国際公開第2005/089024号に記載のものが挙げられ、その好ましい例も同様である。
正孔注入層形成用組成物における、電子受容性化合物の含有量は、通常0.01質量%以上、好ましくは0.05質量%以上、通常20質量%以下、好ましくは10質量%以下である。尚、正孔注入層形成用組成物には、電子受容性化合物が2種以上含まれていてもよく、その場合は2種以上の合計が上記範囲となることが好ましい。
また、正孔注入層形成用組成物中の芳香族アミン重合体に対する電子受容性化合物の含有量は、通常0.1質量%以上、好ましくは1質量%以上、また、通常100質量%以下、好ましくは40質量%以下である。
正孔注入層は、陽極からの正孔注入性を高める点および、正孔輸送性を高める点でカチオンラジカル化合物を含むことが好ましい。
カチオンラジカル化合物としては、正孔輸送性化合物から一電子取り除いた化学種であるカチオンラジカルと、対アニオンとからなるイオン化合物が好ましい。但し、カチオンラジカルが正孔輸送性の芳香族アミン重合体由来である場合、カチオンラジカルは芳香族アミン重合体の芳香族アミン構造から一電子取り除いた構造となる。
ここで、カチオンラジカル化合物は、前述の正孔輸送性化合物と電子受容性化合物を混合することにより生成させることができる。即ち、前述の正孔輸送性化合物と電子受容性化合物とを混合することにより、正孔輸送性化合物から電子受容性化合物へと電子移動が起こり、正孔輸送性化合物のカチオンラジカルと対アニオンとからなるカチオンイオン化合物が生成する。
発光層は、少なくとも発光の性質を有する材料(発光材料)を含有し、好ましくは、さらに電荷輸送性を有する材料(電荷輸送性材料)を含有する。
発光材料は、所望の発光波長で発光し、本発明の効果を損なわない限り特に制限はなく、公知の発光材料を適用可能である。発光材料は、蛍光発光材料でも、燐光発光材料でもよいが、発光効率が良好である材料が好ましく、内部量子効率の観点から燐光発光材料が好ましい。
有機金属錯体の配位子としては、(ヘテロ)アリールピリジン配位子、(ヘテロ)アリールピラゾール配位子などの(ヘテロ)アリール基とピリジン、ピラゾール、フェナントロリンなどが連結した配位子が好ましく、特にフェニルピリジン配位子、フェニルピラゾール配位子が好ましい。これらの配位子はさらに置換基を有していてもよい。ここで、(ヘテロ)アリールとは、アリール基またはヘテロアリール基を表す。
電荷輸送性材料は、従来、有機電界発光素子の発光層に用いられている化合物等を用いることができ、特に、発光層のホスト材料として使用されている化合物が好ましい。
本実施形態における陰極は本発明における第2導電層である。
陰極9は、発光層5側の層に電子を注入する役割を果たす電極である。
陰極9の材料としては、通常、アルミニウム、金、銀、ニッケル、パラジウム、白金等の金属、インジウム及び/又はスズの酸化物等の金属酸化物、ヨウ化銅等のハロゲン化金属、カーボンブラック、或いは、ポリ(3-メチルチオフェン)、ポリピロール、ポリアニリン等の導電性高分子等により構成される。これらのうち、効率よく電子注入を行なうには、仕事関数の低い金属が好ましく、例えば、スズ、マグネシウム、インジウム、カルシウム、アルミニウム、銀等の適当な金属又はそれらの合金などが用いられる。具体例としては、マグネシウム-銀合金、マグネシウム-インジウム合金、アルミニウム-リチウム合金等の低仕事関数の合金電極などが挙げられる。
陰極9の形成方法は、上記材料により、適宜公知の方法を用いればよいが、真空蒸着法やスパッタリング法等が好適に用いられる。
陰極9の膜厚は、必要とする透明性により異なる。透明性が必要とされる場合は、可視光の透過率を、通常60%以上、好ましくは80%以上とすることが好ましい。この場合、陰極9の厚みは通常5nm以上、好ましくは10nm以上であり、また、通常1000nm以下、好ましくは500nm以下程度である。不透明でよい場合は陰極9の厚みは任意である。また、さらには、上記の陰極9の上に異なる導電材料を積層することも可能である。
本発明の有機電界発光素子には上記必須の層の間に他の機能層を有していてもよい。他の機能層の例を以下に示す。
(正孔阻止層)
発光層5と後述の電子注入層8との間に、正孔阻止層6を設けてもよい。正孔阻止層6は、電子輸送層のうち、更に陽極2から移動してくる正孔を陰極9に到達するのを阻止する役割をも担う層である。正孔阻止層6は、発光層5の上に、発光層5の陰極9側の界面に接するように積層される層である。
正孔阻止層6を構成する材料に求められる物性としては、電子移動度が高く正孔移動度が低いこと、エネルギーギャップ(HOMO、LUMOの差)が大きいこと、励起三重項エネルギー準位(T1)が高いことなどが挙げられる。このような条件を満たす正孔阻止層6の材料としては、例えば、ビス(2-メチル-8-キノリノラト)(フェノラト)アルミニウム、ビス(2-メチル-8-キノリノラト)(トリフェニルシラノラト)アルミニウム等の混合配位子錯体、ビス(2-メチル-8-キノラト)アルミニウム-μ-オキソ-ビス-(2-メチル-8-キノリノラト)アルミニウム二核金属錯体等の金属錯体、ジスチリルビフェニル誘導体等のスチリル化合物(日本国特開平11-242996号公報)、3-(4-ビフェニルイル)-4-フェニル-5(4-tert-ブチルフェニル)-1,2,4-トリアゾール等のトリアゾール誘導体(日本国特開平7-41759号公報)、バソクプロイン等のフェナントロリン誘導体(日本国特開平10-79297号公報)などが挙げられる。更に、国際公開第2005/022962号に記載の2,4,6位が置換されたピリジン環を少なくとも1個有する化合物も、正孔阻止層6の材料として好ましい。
正孔阻止層6の膜厚は、本発明の効果を著しく損なわない限り任意である。正孔阻止層6の膜厚は、通常0.3nm以上、好ましくは0.5nm以上、また、通常100nm以下、好ましくは50nm以下である。
電子輸送層7は、発光層と陰極の間に設けられた電子を輸送するための層である。
電子輸送層7の電子輸送材料としては、通常、陰極又は陰極側の隣接層からの電子注入効率が高く、かつ、高い電子移動度を有し注入された電子を効率よく輸送することができる化合物を用いる。このような条件を満たす化合物としては、例えば、8-ヒドロキシキノリンのアルミニウム錯体やリチウム錯体などの金属錯体(日本国特開昭59-194393号公報)、10-ヒドロキシベンゾ[h]キノリンの金属錯体、オキサジアゾール誘導体、ジスチリルビフェニル誘導体、シロール誘導体、3-ヒドロキシフラボン金属錯体、5-ヒドロキシフラボン金属錯体、ベンズオキサゾール金属錯体、ベンゾチアゾール金属錯体、トリスベンズイミダゾリルベンゼン(米国特許第5645948号明細書)、キノキサリン化合物(日本国特開平6-207169号公報)、フェナントロリン誘導体(日本国特開平5-331459号公報)、2-t-ブチル-9,10-N,N’-ジシアノアントラキノンジイミン、トリアジン化合物誘導体、n型水素化非晶質炭化シリコン、n型硫化亜鉛、n型セレン化亜鉛などが挙げられる。
電子輸送層の膜厚は、本発明の効果を著しく損なわない限り任意であるが、通常1nm以上、好ましくは5nm以上、また、通常300nm以下、好ましくは100nm以下の範囲である。
陰極9から注入された電子を効率良く発光層5に注入するために、電子輸送層7と後述の陰極9との間に電子注入層8を設けてもよい。電子注入層8は、無機塩などからなる。
電子注入層8の材料としては、例えばフッ化リチウム(LiF)、フッ化マグネシウム(MgF2)、酸化リチウム(Li2O)、炭酸セシウム(II)(CsCO3)等が挙げられる(Applied Physics Letters,1997年,Vol.70、pp.152;日本国特開平10-74586号公報;IEEE Transactions on Electron Devices,1997年,Vol.44,pp.1245;SID 04 Digest,pp.154等参照)。
電子注入層8は、電荷輸送性を伴わない場合が多いため、電子注入を効率よく行なうには、極薄膜として用いることが好ましく、その膜厚は、通常0.1nm以上、好ましくは5nm以下である。
本発明におけるショートとは、印加電流は電圧に略比例して増大するものの、発光輝度は通電電流に伴って比例的に増加することがなく、殆ど発光しないことをいう。従って、ショートした素子は、輝度が低い、もしくは発光しないため、有機電界発光素子として十分に機能しない。また、本発明におけるリークとは、印加電圧に対して、本来想定される電流値に比べて過大に電流が流れる現象のことをいう。有機電界発光素子にリークが存在した場合、リーク箇所に電流が集中するため、その他の部分の輝度が低下する、または、リーク箇所に過大な熱が発生するために、そこを中心に有機電界発光素子が劣化し、最終的には発光しなくなる。
このとき、ショートしていた場合、電流は、電圧に略比例して増大するものの、発光輝度は通電電流に伴って比例的に増加することがなく、殆ど発光しない。従って、ショートしている素子の判定は比較的容易である。
なお、リークの判定方法の詳細は、後述の実施例に記載の通りである。
<リーク発生の有無の判定―1(逆電圧印加手法)>
完成した有機電界発光素子に、-3.1V~-9Vまで-0.1V刻みで電圧を印加して電流を測定し、左記印加電圧範囲内における-0.1V当たりの電流の変化量の絶対値の、電圧の絶対値が低い方の値における電流値に対する割合(以下Zと記載)を%で算出し、全測定電圧範囲において、Zの値が20%を超える値が一つでも得られた場合は「リークあり」、全ての値が20%以下である場合を「リークなし」と判定した。より厳密には、-3.1V~-8.9Vの範囲内のある測定電圧をV0とし、その際の電流をJ[V0]とした場合、
Z=|((J[V0-0.1]-J[V0])/J[V0])|×100(%)
について、V0=-3.1~-8.9Vの範囲で0.1Vごとに算出し、全てのZの値が20%以下である場合は「リークなし」、それ以外は「リークあり」とした。
なお、<リーク発生の有無の判定―1>は、後述の<リーク発生の有無の判定―2>より、判定条件が厳しいものである。
<リーク発生の有無の判定―2(逆電圧印加手法)>
リーク発生の有無の判定―1に準じて、判定を行った。但し、Zの値が50%を超える値が一つでも得られた場合は「リークあり」、全ての値が50%以下である場合を「リークなし」と判定した。
製造方法、材質、研磨の有無等を変更した種々のガラス基材およびガラス基板メーカーのガラス基材およびガラス基板(A~H)について、うねり正接、Na2OおよびK2O含有率、表面欠陥の密度について評価した結果を示す。各パラメータの評価条件は以下の通りである。
測定装置:SURFCOM M480A(東京精密社製)
ろ波中心線うねり測定(JIS B0601:’94)に基づく設定
(a)評価長さ = 80mm以上100mm未満
(b)測定速度 = 3.0mm/sec.
(c)カットオフ値(λc-λf) 0.8-8.0mm
(d)フィルタ種別 = 2RC(補償)
[Na2OおよびK2O含有率]
測定手法:蛍光X線分光分析(XRF)
測定装置:RIX-3001(リガク社製)
XRFの測定条件
(a)測定室真空度 = 10Pa以下
(b)X線管球電圧-電流 = 50kV-50mA
[表面欠陥の密度]
測定領域:7mm×10.5mm角の領域4面
ITO膜厚:110nm、または150nm
光学顕微鏡:LV100D(ニコン社製)
対物倍率/接眼倍率:20/10倍
各ガラス基材(H)およびガラス基板(A~G)の緒元及び測定結果を表12に示す。
図1に示した層構成から、正孔阻止層6及び電子輸送層7を省略した構造を有する9mm角の発光領域を持つ有機電界発光素子を作製した。
まず、陽極としてITOが110nm成膜されているガラス基板Aを、発光エリアが9mm角になるようにITOをパターニングして準備した。
次いで、下記式(A)に示す繰り返し構造を有する高分子化合物(Mw=65,000)と下記式(B)に示す繰り返し構造を有する高分子化合物(Mw=85,000)、4-イソプロピル-4’-メチルジフェニルヨードニウムテトラキス(ペンタフルオロフェニル)ボラートとを質量比5対95対15で混合し、混合物の合計濃度が5.5質量%となるように安息香酸エチルに溶解させた組成物を調製した。この組成物を、大気雰囲気中で、前記ガラス基板A上に、2850rpmで30秒スピンコートした。その後、230℃で一時間加熱することで、膜厚150nmの正孔注入層を形成した。
次いで、正孔輸送層として、下記に示す4,4’-ビス[N-(9-フェナントリル)-N-フェニル-アミノ]ビフェニル(PPD)を膜厚45nmとなるように真空蒸着法により製膜した。
次いで、発光層としてトリス(8-ヒドロキシキノリナート)アルミニウム(Alq3)を膜厚60nmとなるように真空蒸着法により製膜した。
<電子注入層の形成>
次いで、発光層上にフッ化リチウム(LiF)を膜厚0.5nmとなるように真空蒸着法によって蒸着し、電子注入層を形成した。
次いで、アルミニウムを膜厚80nmとなるように真空蒸着法によって蒸着し、陰極を形成した。
<封止工程>
引き続き、窒素グローブボックス中で、ガラス板の外周部に光硬化性樹脂を塗布し、中央部に水分ゲッターシートを設置した。上記ガラス板と第2の電極4まで形成した素子とを貼り合わせ、その後、光硬化性樹脂が塗布された領域のみに紫外光を照射し、樹脂を硬化させた。これにより、有機電界発光素子が得られた。
なお、本実施例1-1においては、正孔注入層のみを湿式成膜しているため、本発明の電荷注入輸送層に相当するのは正孔注入層のみである。
正孔注入層を、1950rpmで30秒スピンコートし、膜厚200nmの正孔注入層を形成した点以外は実施例1-1と同様に有機電界発光素子を作成した。
正孔注入層を、910rpmで30秒スピンコートし、膜厚400nmの正孔注入層を形成した点以外は実施例1-1と同様に有機電界発光素子を作成した。
正孔注入輸送層を、組成物濃度6.5wt%の溶液を用いて1050rpmで30秒スピンコートし、膜厚500nmの正孔注入層を形成した点以外は実施例1-1と同様に有機電界発光素子を作成した。
正孔注入輸送層を、5500rpmで30秒スピンコートし、膜厚100nmの正孔注入層を形成した点以外は実施例1-1と同様に有機電界発光素子を作成した。
フュージョン法により製造されたガラス基板Fを用いて、膜厚30nmの正孔注入輸送層を形成した点以外は実施例1-1と同様に有機電界発光素子を作成した。
完成した有機電界発光素子に、-3.1V~-9Vまで-0.1V刻みで電圧を印加して電流を測定した。リークの有無の判定は前記した方法(リーク発生の有無の判定―1)により行った。この判定を、実施例1-1~4-1、比較例1-1、及び参考例1-1のそれぞれについて作製した複数の有機電界発光素子に対して実施し、リーク有りと判定された有機電界発光素子の数の割合を「リーク発生確率」として求めた。結果を表13に示す。
また、フロート法で製造され、研磨を行わない安価なガラス基板、すなわち、うねり正接の最小値が4.00×10-6以上又はうねり正接の最大値が22×10-6以上とうねりの大きいガラス基材を用いて有機電界発光素子を作製した場合であっても、陽極の膜厚が130nm以上であり、電荷注入層が、架橋された芳香族アミン重合体を含むこと(本願第一の発明)で、従来の高価なガラス基板と同等以上の割合でリークの無い有機電界発光素子を作製することが可能であることが判った。
実施例1-1~実施例4-1、比較例1-1及び参考例1-1と同様にして実施例1-2~実施例4-2、比較例1-2及び参考例1-2の有機電界発光素子を作製し、リークの有無の判定を、<リーク発生の有無の判定―2>により行った。
結果を表14に示す。
図1に示した層構成から、正孔阻止層6及び電子輸送層7を省略した構造を有する7mm角の発光領域を持つ有機電界発光素子を作製した。
<ITO基板への塗布型正孔注入輸送層の形成>
まず、陽極としてITOが150nm成膜されているガラス基板Iを、発光エリアが7mm角になるようにITOをパターニングして準備した。
次いで、下記式(C)に示す繰り返し構造を有する高分子化合物(Mw=83,000)と4-イソプロピル-4’-メチルジフェニルヨードニウムテトラキス(ペンタフルオロフェニル)ボラートとを質量比100対15で混合し、混合物の合計濃度が5.0質量%となるように安息香酸エチルに溶解させた組成物を調製した。この組成物を、大気雰囲気中で、前記ガラス基板I上に、6000rpmで30秒スピンコートした。その後、230℃で一時間加熱することで、膜厚73nmの正孔注入層を形成した。
次いで、下記式(D)に示す繰り返し構造を有する高分子化合物(Mw=60,000)を濃度が3.0質量%となるようにシクロヘキシルベンゼンに溶解させた組成物を調製した。
次いで、発光層の形成から封止工程までを実施例1-1と同様に実施し、有機電界発光素子を作製した。
なお、本実施例5においては、正孔注入層と塗布型正孔輸送層を湿式成膜しているため、本発明の電荷注入輸送層に相当するのは正孔注入層と塗布型正孔輸送層である。
正孔注入層を、4200rpmで30秒スピンコートし、膜厚88nmの正孔注入層を形成し、塗布型正孔輸送層を2250rpmで120秒スピンコートし、膜厚62nmの塗布型正孔輸送層を形成した点以外は実施例5と同様に有機電界発光素子を作製した。
正孔注入層を、2500rpmで30秒スピンコートし、膜厚122nmの正孔注入層を形成し、塗布型正孔輸送層を組成物濃度4.0wt%の溶液を用いて3200rpmで120秒スピンコートし、膜厚79nmの塗布型正孔輸送層を形成した点以外は実施例5と同様に有機電界発光素子を作製した。
正孔注入層を、正孔注入層を組成物濃度7.0wt%の溶液を用いて、4300rpmで30秒スピンコートし、膜厚187nmの正孔注入層を形成し、塗布型正孔輸送層を組成物濃度5.0wt%の溶液を用いて3500rpmで120秒スピンコートし、膜厚118nmの塗布型正孔輸送層を形成した点以外は実施例5と同様に有機電界発光素子を作製した。
正孔注入層を、2750rpmで30秒スピンコートし、膜厚245nmの正孔注入層を形成し、塗布型正孔輸送層を2500rpmで120秒スピンコートし、膜厚158nmの塗布型正孔輸送層を形成した点以外は実施例8と同様に有機電界発光素子を作製した。
正孔注入層を、2150rpmで30秒スピンコートし、膜厚303nmの正孔注入層を形成し、塗布型正孔輸送層を組成物濃度6.0wt%の溶液を用いて2500rpmで120秒スピンコートし、膜厚198nmの塗布型正孔輸送層を形成した点以外は実施例8と同様に有機電界発光素子を作製した。
正孔注入層を組成物濃度2.5wt%の溶液を用いて、3500rpmで30秒スピンコートし、膜厚32nmの正孔注入層を形成し、塗布型正孔輸送層を、組成物濃度2.0wt%の溶液を用いて、3500rpmで120秒スピンコートし、膜厚28nmの塗布型正孔輸送層を形成した点以外は実施例5と同様に有機電界発光素子を作製した。
正孔注入層を組成物濃度3.5wt%の溶液を用いて、2600rpmで30秒スピンコートし、膜厚61nmの正孔注入層を形成し、塗布型正孔輸送層を、3800rpmで120秒スピンコートし、膜厚44nmの塗布型正孔輸送層を形成した点以外は実施例5と同様に有機電界発光素子を作製した。
正孔注入層、塗布型正孔輸送層を下記のように形成した以外は、実施例5と同様にして有機電界発光素子を作製した。
下記式(F)に示す繰り返し構造を有する高分子化合物(Mw=39,000)と4-イソプロピル-4’-メチルジフェニルヨードニウムテトラキス(ペンタフルオロフェニル)ボラートとを質量比100対20で混合し、混合物の合計濃度が5.0質量%となるように安息香酸エチルに溶解させた組成物を調製した。この組成物を、大気雰囲気中で、前記ガラス基板I上に、2200rpmで30秒スピンコートした。その後、230℃で一時間加熱することで、膜厚93nmの正孔注入層を形成した。
正孔注入層、塗布型正孔輸送層を下記のように形成した以外は、実施例5と同様にして有機電界発光素子を作製した。
下記式(G)に示す繰り返し構造を有する高分子化合物(Mw=29,000)と4-イソプロピル-4’-メチルジフェニルヨードニウムテトラキス(ペンタフルオロフェニル)ボラートとを質量比100対40で混合し、混合物の合計濃度が4.0質量%となるように安息香酸エチルに溶解させた組成物を調製した。この組成物を、大気雰囲気中で、前記ガラス基板I上に、3100rpmで30秒スピンコートした。その後、230℃で一時間加熱することで、膜厚59nmの正孔注入層を形成した。
正孔注入層を、組成物濃度5.0wt%の溶液を用いて、3400rpmで30秒スピンコートし、膜厚79nmの正孔注入層を形成し、塗布型正孔輸送層を組成物濃度3.0wt%の溶液を用いて、2950rpmで120秒スピンコートし、膜厚50nmの塗布型正孔輸送層を形成した点以外は比較例4と同様に有機電界発光素子を作製した。
正孔注入層を、2700rpmで30秒スピンコートし、膜厚92nmの正孔注入層を形成し、塗布型正孔輸送層を2950rpmで120秒スピンコートし、膜厚59nmの塗布型正孔輸送層を形成した点以外は比較例5と同様に有機電界発光素子を作製した。
正孔注入層を、組成物濃度5.0wt%の溶液を用いて、2300rpmで30秒スピンコートし、膜厚107nmの正孔注入層を形成し、塗布型正孔輸送層を3000rpmで120秒スピンコートし、膜厚85nmの塗布型正孔輸送層を形成した点以外は比較例4と同様に有機電界発光素子を作製した。
正孔注入層を、組成物濃度7.0wt%の溶液を用いて、2300rpmで30秒スピンコートし、膜厚183nmの正孔注入層を形成し、塗布型正孔輸送層を組成物濃度5.0wt%の溶液を用いて、2300rpmで120秒スピンコートし、膜厚118nmの塗布型正孔輸送層を形成した点以外は比較例5と同様に有機電界発光素子を作製した。
正孔注入層を、組成物濃度8.0wt%の溶液を用いて、2750rpmで30秒スピンコートし、膜厚232nmの正孔注入層を形成し、塗布型正孔輸送層を2000rpmで120秒スピンコートし、膜厚158nmの塗布型正孔輸送層を形成した点以外は比較例8と同様に有機電界発光素子を作製した。
正孔注入層を、2050rpmで30秒スピンコートし、膜厚301nmの正孔注入層を形成し、塗布型正孔輸送層を組成物濃度6.0wt%の溶液を用いて、2500rpmで120秒スピンコートし、膜厚198nmの塗布型正孔輸送層を形成した点以外は比較例9と同様に有機電界発光素子を作製した。
(1)実施例の有機電界発光素子は、従来の高コストのフュージョン法によるガラス基材を用いた場合(参考例1-1及び1-2)に準じたレベルのリークの発生率である。
(2)実施例の有機電界発光素子は、フロート法によるガラスであっても電荷注入輸送層(正孔注入輸送層)の膜厚が小さい場合(比較例1-1、比較例1-2、比較例2及び3)に比べて、リークの発生が抑制される。なお、表14中の実施例の一部は、表15中の比較例よりリークの発生率が高い(例えば、実施例1-2は、比較例8~10よりもリーク発生率が高い)。但し、表中のデータは、電荷注入輸送層(正孔注入輸送層)の膜厚がほぼ同等で、かつ、電荷注入輸送層(正孔注入輸送層)に含まれる芳香族アミン重合体の種類を変更したもの同士(架橋の有無)を対比すべきものである。例えば、実施例1-2と比較例6とは、いずれも正孔注入輸送層の膜厚が約150nmであるが、正孔注入輸送層に架橋された芳香族アミン重合体を用いている実施例1-2は、正孔注入輸送層に架橋された芳香族アミン重合体を用いていない比較例6に比べ、リークの発生が抑制されていることが分かる。
(3)<リーク発生の有無の判定―2>による判定を行った実験において、うねり正接の最小値が4.20以上であるガラス基板Aを用いた場合(実施例1-2~4-2、比較例1-2)、電荷注入輸送層(正孔注入輸送層)の膜厚が200nmのときにリーク発生率0%と良好な結果が得られた。一方、うねり正接の最小値が4.00以上であるガラス基板Iを用いた場合(実施例5~実施例10、比較例2、3)、電荷注入輸送層(正孔注入輸送層)の膜厚が201nmであってもリーク発生率は0%ではなく、305nmのときに0%であった。
2 陽極
3 正孔注入層
4 正孔輸送層
5 発光層
6 正孔阻止層
7 電子輸送層
8 電子注入層
9 陰極
10 有機電界発光素子
11 正孔注入輸送層
Claims (26)
- ガラス基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子であって、
(1)該ガラス基材の該第1導電層側表面のうねり正接の最小値が4.00×10-6以上、又は該うねり正接の最大値が22×10-6以上であり、
(2)該電荷注入輸送層は湿式成膜法により形成された層であり、
(3)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(4)該電荷注入輸送層の膜厚が130~1000nmであり、
(5)該電荷注入層が、架橋された芳香族アミン重合体を含む、
有機電界発光素子。 - 前記ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上である、請求項1に記載の有機電界発光素子。
- 前記ガラス基材が、Na2OおよびK2Oの少なくとも一方を1.0質量%以上含有する、請求項1又は請求項2に記載の有機電界発光素子。
- 前記電荷注入輸送層の膜厚が130~500nmである、請求項1~請求項3のいずれか1項に記載の有機電界発光素子。
- 前記ガラス基材がフロート法により製造されたものである、請求項1~請求項4のいずれか1項に記載の有機電界発光素子。
- 前記ガラス基材が未研磨のガラス基材である、請求項5に記載の有機電界発光素子。
- 基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子であって、
(1)該電荷注入輸送層は湿式成膜法により形成された層であり、
(2)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(3)該電荷注入輸送層の膜厚が130~1000nmであり、
(4)該電荷注入層が、架橋された芳香族アミン重合体を含む、
ことを特徴とする有機電界発光素子。 - 前記基材がガラス基材であり、該ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上である、請求項9に記載の有機電界発光素子。
- 前記ガラス基材がフロート法により製造されたものである、請求項10に記載の有機電界発光素子。
- 前記ガラス基材が未研磨のガラス基材である、請求項11に記載の有機電界発光素子。
- 前記電荷注入輸送層の膜厚が130~500nmである、請求項9~請求項12のいずれか1項に記載の有機電界発光素子。
- ガラス基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子の製造方法であって、
(1)該ガラス基材として、該第1導電層側表面のうねり正接の最小値が4.00×10-6以上、又は該うねり正接の最大値が22×10-6以上であるガラス基材を、該うねり正接を有する面が該第1導電層側表面となるように用い、
(2)該電荷注入輸送層は湿式成膜法により形成され、
(3)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(4)該電荷注入層を、架橋性基を有する芳香族アミン重合体と溶媒とを含む組成物を湿式成膜法にて塗布、乾燥、架橋させることによって形成し、
(5)該電荷注入輸送層を130~1000nmの膜厚で形成する、
有機電界発光素子の製造方法。 - 前記ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上である、請求項14に記載の有機電界発光素子の製造方法。
- 前記ガラス基材として、Na2OおよびK2Oの少なくとも一方を1.0質量%以上含有するガラス基材を用いる、請求項14又は請求項15に記載の有機電界発光素子の製造方法。
- 前記電荷注入輸送層の膜厚が130~500nmである、請求項14~請求項16のいずれか1項に記載の有機電界発光素子の製造方法。
- 前記ガラス基材として、フロート法により製造されたガラス基材を用いる、請求項14~請求項17のいずれか1項に記載の有機電界発光素子の製造方法。
- 前記ガラス基材として、フロート法により製造され、かつ、未研磨であるガラス基材を用いる、請求項18に記載の有機電界発光素子の製造方法。
- 基材上に、少なくとも、第1導電層と、電荷注入輸送層と、発光層と、第2導電層とが積層された有機電界発光素子の製造方法であって、
(1)該電荷注入輸送層は湿式成膜法により形成され、
(2)該電荷注入輸送層は第1導電層に接する電荷注入層を含み、
(3)該電荷注入輸送層の膜厚は130~1000nmであり、
(4)該電荷注入層を、架橋性基を有する芳香族アミン重合体と溶媒とを含む組成物を湿式成膜法にて塗布、乾燥、架橋させることによって形成する、
有機電界発光素子の製造方法。 - 前記基材がガラス基材であり、該ガラス基材上に前記第1導電層を形成した状態における表面欠陥の密度が、2.0個/cm2以上である、請求項20に記載の有機電界発光素子の製造方法。
- 前記ガラス基材として、フロート法により製造されたガラス基材を用いる、請求項は21に記載の有機電界発光素子の製造方法。
- 前記ガラス基材として、フロート法により製造され、かつ、未研磨のガラス基材を用いる、請求項22に記載の有機電界発光素子の製造方法。
- 前記電荷注入輸送層の膜厚が130~500nmである、請求項20~請求項23のいずれか1項に記載の有機電界発光素子の製造方法。
- ガラス基材上に、少なくとも第1導電層と、湿式成膜法により形成された、電荷輸送材料を含有する電荷注入輸送層と、発光層と、第2導電層とをこの順に有する有機電界発光素子であって、
該ガラス基材がフロート法により製造され、
該第1導電層形成側の該ガラス基材表面が未研磨の状態であり、
該電荷注入輸送層の膜厚が、該第1導電層の膜厚の1.3倍以上である、有機電界発光素子。 - ガラス基材上に、少なくとも第1導電層と、湿式成膜法により形成された、電荷輸送材料を含有する電荷注入輸送層と、発光層と、第2導電層とをこの順に有する有機電界発光素子であって、
該第1導電層形成側の該ガラス基材表面のうねり正接の最小値が4.20×10-6以上、又は該うねり正接の最大値が22×10-6以上であり、
該電荷注入輸送層の膜厚が、該第1導電層の膜厚の1.3倍以上である、有機電界発光素子。
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TW201419942A (zh) | 2014-05-16 |
CN104604332A (zh) | 2015-05-06 |
EP2894942A4 (en) | 2015-10-07 |
US20150179963A1 (en) | 2015-06-25 |
KR20150052024A (ko) | 2015-05-13 |
CN104604332B (zh) | 2017-03-29 |
JPWO2014038559A1 (ja) | 2016-08-12 |
EP2894942A1 (en) | 2015-07-15 |
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