JP7107753B2 - Method for manufacturing electronic device and method for driving inkjet printer - Google Patents

Description

The present invention relates to an electronic device manufacturing method and an inkjet printing apparatus driving method.

The electronic device comprises a first electrode layer and a second electrode layer provided on a substrate, and one or more functional layers provided between the first electrode layer and the second electrode layer. In manufacturing this electronic device, at least one of the first electrode layer, the one or more functional layers and the second electrode layer is coated with an ink jet printing apparatus as described, for example, in US Pat. can be formed using an inkjet printing method using

JP-A-10-153967

In a method for manufacturing an electronic device including a step of forming a layer by an inkjet printing method, there is a case where the ejection of ink is stopped and the inkjet printing apparatus is put on standby when the layer is not formed. When the inkjet printing apparatus is put on standby in this way, it is known to supply a voltage to the piezoelectric element in the inkjet head of the inkjet printing apparatus to preliminarily vibrate the piezoelectric element.

However, when waiting as described above, the ink contained in the inkjet printing apparatus may aggregate or solidify. In this case, the ink ejection port is clogged, and when the inkjet printing apparatus is used again, there is a problem in the ejection of the ink, and the production efficiency of the electronic device is lowered.

Accordingly, an object of one aspect of the present invention is to provide an electronic device manufacturing method capable of improving production efficiency. Another aspect of the present invention provides a method of driving an inkjet printing apparatus capable of preventing clogging of ink ejection ports during standby.

A method for manufacturing an electronic device according to one aspect of the present invention includes a first electrode layer and a second electrode layer provided on a substrate, and one electrode layer provided between the first electrode layer and the second electrode layer. or a method for manufacturing an electronic device comprising a plurality of functional layers, wherein at least one of the first electrode layer, the one or more functional layers, and the second electrode layer is formed by A layer forming step formed by an inkjet printing method using an inkjet printing device, and a standby step of stopping ejection of ink from the inkjet printing device and waiting the inkjet printing device, While supplying electric power to the inkjet printing device, the voltage supply to the piezoelectric element of the inkjet head of the inkjet printing device is interrupted.

In the standby process, voltage supply to the piezoelectric element is interrupted. Therefore, almost no electric field exists in the vicinity of the piezoelectric element compared to the case where voltage is applied to the piezoelectric element. Therefore, even if ink exists in the vicinity of the piezoelectric element, the components in the ink are prevented from aggregating due to electrical force and from solidifying due to chemical reactions caused by the electric field. As a result, when the layer forming process is carried out again after the standby process, the layer forming process can be carried out without carrying out the work for resolving the problems associated with the aggregation and solidification (for example, clogging of the ink ejection port). Alternatively, at least the number of times of work for solving the problem can be reduced. Therefore, the production efficiency of electronic devices is improved.

In the layer forming step, before forming the at least one layer by ejecting the ink from the inkjet printing device, the ink may be ejected from the inkjet printing device outside the formation region of the at least one layer. In the standby process, since the voltage supply to the piezoelectric element is cut off, so-called preliminary vibration is not performed. Therefore, the meniscus shape of the ink may differ from the desired state. Therefore, in the layer forming step, before ejecting ink from the inkjet printing device to form the at least one layer, by ejecting ink from the inkjet printing device outside the formation region of the at least one layer, After stabilizing the desired meniscus shape, the at least one layer can be formed.

The ink ejected from the inkjet printing apparatus may be ink for forming a hole injection layer, a hole transport layer, or an electron transport layer. Such ink tends to aggregate and solidify as described above if voltage is supplied to the piezoelectric element while the inkjet printing apparatus is on standby. Therefore, the electronic device manufacturing method including the waiting step is effective when the ink used in the layer forming step is an ink for forming a hole injection layer, a hole transport layer, or an electron transport layer.

The ink ejected from the inkjet printing device may contain an aromatic hydrocarbon compound and an alkali metal salt or an alkaline earth metal salt. Such ink tends to aggregate and solidify as described above if voltage is supplied to the piezoelectric element while the inkjet printing apparatus is on standby. Therefore, the electronic device manufacturing method including the waiting step is effective when the ink used in the layer forming step is an ink containing an aromatic hydrocarbon compound and an alkali metal salt or an alkaline earth metal salt.

The piezoelectric element included in the inkjet head may be insulated. In this case, it becomes even more difficult for the ink to coagulate.

In the standby step, the inkjet printing device may be on standby for one hour or longer. If the inkjet printing apparatus is kept on standby for one hour or more while voltage is being supplied to the piezoelectric element, the aggregation and solidification described above are likely to occur. Therefore, the electronic device manufacturing method including the standby step is effective when the inkjet printing apparatus is kept on standby for one hour or more.

The inkjet printing apparatus may be a circulation type inkjet apparatus that circulates the ink between an ink supply unit and an inkjet head that ejects the ink.

A method of driving an inkjet printing device according to another aspect of the present invention includes an ejection step of ejecting ink from the inkjet printing device, and a standby step of stopping ejection of the ink from the inkjet printing device and putting the inkjet printing device on standby. and, in the standby step, power is supplied to the inkjet printing device, and voltage supply to the piezoelectric element of the inkjet head of the inkjet printing device is interrupted.

In the standby process, voltage supply to the piezoelectric element is interrupted. Therefore, almost no electric field exists in the vicinity of the piezoelectric element compared to the case where voltage is applied to the piezoelectric element. Therefore, even if ink exists in the vicinity of the piezoelectric element, the components in the ink are prevented from aggregating due to electrical force and from solidifying due to chemical reactions caused by the electric field. As a result, when the ejection process is carried out after the standby process, the ejection process can be carried out without performing the work of eliminating the clogging of the ink ejection openings caused by the aggregation and solidification.

According to one aspect of the present invention, it is possible to provide an electronic device manufacturing method capable of improving production efficiency. According to another aspect of the present invention, it is possible to provide a method of driving an inkjet printing apparatus capable of preventing clogging of ink ejection ports during standby.

FIG. 1 is a schematic diagram showing a schematic configuration of an organic EL device (electronic device) manufactured using an electronic device manufacturing method according to an embodiment. FIG. 2 is a schematic diagram for explaining an example of an inkjet device used in a layer forming step of the electronic device manufacturing method according to the embodiment. FIG. 3 is a schematic diagram for explaining a layer forming step included in the method for manufacturing an electronic device according to one embodiment.

Embodiments of the present invention will be described below with reference to the drawings. The same elements are denoted by the same reference numerals, and overlapping descriptions are omitted. The dimensional proportions of the drawings do not necessarily match those of the description.

FIG. 1 is a schematic diagram showing a schematic configuration of an organic electroluminescence device (hereinafter also referred to as an “organic EL device”) manufactured using a method for manufacturing an electronic device according to one embodiment. The organic EL device 10 has a substrate 12 , an anode layer (first electrode layer) 14 , a device functional portion 16 and a cathode layer (second electrode layer) 18 . The anode layer 14 , the device function portion 16 and the cathode layer 18 are laminated on the substrate 12 in the order of the anode layer 14 , the device function portion 16 and the cathode layer 18 . The organic EL device 10 may be a top emission type organic EL device or a bottom emission type organic EL device. Hereinafter, unless otherwise specified, the organic EL device 10 is a bottom emission type organic EL device.

[substrate]
The substrate 12 is translucent to light emitted from the organic EL device 10 (including visible light with a wavelength of 400 nm to 800 nm). An example thickness of the substrate 12 is 30 μm to 1100 μm.

Substrate 12 may be a rigid substrate, such as glass substrates and silicon substrates, or a flexible substrate, such as plastic substrates and polymer films. A flexible substrate is a substrate that can be bent without being sheared or broken even when a predetermined force is applied to the substrate.

When the substrate 12 is a rigid substrate, the thickness of the substrate 12 is, for example, 50 μm to 1100 μm. If the substrate 12 is a flexible substrate, the thickness of the substrate 12 is, for example, 30 μm to 700 μm.

A barrier layer having a moisture barrier function may be formed on the substrate 12 . The barrier layer may have a gas (for example, oxygen) barrier function in addition to the moisture barrier function.

[Anode layer]
Anode layer 14 is provided on substrate 12 . An electrode exhibiting optical transparency is used for the anode layer 14 . A thin film containing a metal oxide, a metal sulfide, a metal, or the like with high electrical conductivity can be used as the light-transmitting electrode. A thin film having a high light transmittance is preferably used as the light-transmitting electrode. Anode layer 14 may have a network structure made of a conductor (eg, metal). The thickness of the anode layer 14 can be determined in consideration of light transmittance, electrical conductivity, and the like. The thickness of the anode layer 14 is generally 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 50 nm to 500 nm.

Materials for the anode layer 14 include, for example, indium oxide, zinc oxide, tin oxide, indium tin oxide (abbreviated as ITO), indium zinc oxide (abbreviated as IZO), gold, platinum, silver, Copper etc. are mentioned, Among these, ITO, IZO, or tin oxide is preferable. Anode layer 14 may be formed as a thin film made of the exemplified materials. Organic substances such as polyaniline and its derivatives, polythiophene and its derivatives may be used as the material of the anode layer 14 . In this case, the anode layer 14 can be formed as a transparent conductive film.

[Device function part]
The device functional portion 16 is a functional portion that contributes to light emission of the organic EL device 10 such as charge transfer and charge recombination according to the voltage applied to the anode layer 14 and the cathode layer 18 . The device functional section 16 has a light emitting layer which is a functional layer. As will be described later, the device functional section 16 may have functional layers other than the light emitting layer. That is, the device function section 16 has one or more functional layers.

A light emitting layer is a functional layer having a function of emitting light (including visible light). The light-emitting layer is an organic layer and is usually composed of an organic substance that mainly emits at least one of fluorescence and phosphorescence, or this organic substance and a dopant material that assists this. A dopant material is added, for example, to improve the luminous efficiency or change the luminous wavelength. The organic substance may be a low-molecular-weight compound or a high-molecular-weight compound. The thickness of the light-emitting layer is, for example, 2 nm to 200 nm.

Examples of organic substances that are light-emitting materials that mainly emit at least one of fluorescence and phosphorescence include the following dye-based materials, metal complex-based materials, and polymer-based materials.

(pigment-based material)
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, and thiophene ring compounds. , pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, pyrazoline dimers, quinacridone derivatives, coumarin derivatives and the like.

(Metal complex material)
Examples of metal complex materials include rare earth metals such as Tb, Eu, and Dy, or Al, Zn, Be, Ir, Pt, etc., as central metals, and oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, and quinoline. Examples include metal complexes having structures as ligands, such as iridium complexes, metal complexes that emit light from a triplet excited state such as platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolylzinc complexes, benzothiazole zinc complex, azomethyl zinc complex, porphyrin zinc complex, phenanthroline europium complex and the like.

(Polymer material)
Polymeric materials include polyparaphenylenevinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized dye-based materials and metal complex-based luminescent materials. things, etc.

(dopant material)
Examples of dopant materials include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, and phenoxazone.

The device functional section 16 may have at least one functional layer in addition to the light emitting layer. That is, the device function section 16 may have a multilayer structure. For example, at least one of a hole injection layer and a hole transport layer may be provided between the anode layer 14 and the light emitting layer. At least one of an electron transport layer and an electron injection layer may be provided between the light emitting layer and the cathode layer 18 .

The hole injection layer is a functional layer that has a function of improving the efficiency of hole injection from the anode layer 14 to the light emitting layer. The hole injection layer may be an inorganic layer or an organic layer. A hole-injecting material constituting the hole-injecting layer may be a low-molecular-weight compound or a high-molecular-weight compound.

Examples of low-molecular-weight compounds include metal oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, metal phthalocyanine compounds such as copper phthalocyanine, and carbon.

Examples of polymer compounds include polyaniline, polythiophene, polythiophene derivatives such as polyethylenedioxythiophene (PEDOT), polypyrrole, polyphenylenevinylene, polythienylenevinylene, polyquinoline and polyquinoxaline, and derivatives thereof; Conductive polymers such as polymers containing in the main chain or side chain.

The optimum thickness of the hole injection layer varies depending on the material used. The thickness of the hole injection layer may be appropriately determined in consideration of the required properties, ease of film formation, and the like. The thickness of the hole injection layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm.

The hole-transporting layer is a functional layer having a function of improving the efficiency of hole injection from the hole-injecting layer (the anode layer 14 in the form in which the hole-injecting layer does not exist) to the light-emitting layer.

A hole transport layer is an organic layer that includes a hole transport material. The hole-transporting material is not limited as long as it is an organic compound having a hole-transporting function. Examples of organic compounds having a hole transport function include polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amine residues in side chains or main chains, pyrazoline derivatives, arylamine derivatives, and stilbene derivatives. , triphenyldiamine derivative, polyaniline or its derivative, polythiophene or its derivative, polypyrrole or its derivative, polyarylamine or its derivative, poly(p-phenylene vinylene) or its derivative, polyfluorene derivative, having an aromatic amine residue Polymer compounds, and poly(2,5-thienylenevinylene) or derivatives thereof.

Examples of hole transport materials include JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-209988, Also included are hole transport materials described in JP-A-3-37992 and JP-A-3-152184.

The optimum thickness of the hole transport layer varies depending on the material used. The thickness of the hole-transporting layer may be appropriately determined in consideration of the required properties, ease of film formation, and the like. The thickness of the hole transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm.

The electron transport layer is a functional layer that has the function of improving the efficiency of injecting electrons from the electron injection layer (the cathode layer 18 if the electron injection layer does not exist) to the light emitting layer.

The electron-transporting layer is an organic layer containing an electron-transporting material. A known material can be used as the electron transport material. Examples of electron transport materials include materials obtained by doping an aromatic hydrocarbon compound with an alkali metal salt or an alkaline earth metal salt. Specific examples of electron transport materials include oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinone or derivatives thereof, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, Diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorenes or derivatives thereof, and the like.

The thickness of the electron-transporting layer can be appropriately determined in consideration of the required properties, ease of film formation, and the like. The thickness of the electron transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm.

The electron injection layer is a functional layer that has the function of improving the electron injection efficiency from the cathode layer 18 to the light emitting layer.

The electron injection layer may be an inorganic layer or an organic layer. As for the material forming the electron injection layer, an optimum material is appropriately selected according to the type of the light-emitting layer. Examples of materials constituting the electron injection layer include alkali metals, alkaline earth metals, alloys containing one or more of alkali metals and alkaline earth metals, oxides of alkali metals or alkaline earth metals, and halides. , carbonates, or mixtures of these substances. Examples of alkali metals, alkali metal oxides, halides, and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride. , rubidium oxide, rubidium fluoride, cesium oxide, cesium fluoride, and lithium carbonate. Examples of alkaline earth metals, oxides, halides and carbonates of alkaline earth metals include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, fluoride Barium, strontium oxide, strontium fluoride, magnesium carbonate and the like.

In addition, a layer in which a conventionally known electron-transporting organic material and an organometallic complex of an alkali metal are mixed can be used as the electron injection layer.

An example of the layer structure of the device function unit 16 is shown below. In the example of the layer structure below, the anode layer and the cathode layer are also shown in parentheses in order to show the positional relationship between the anode layer 14 and the cathode layer 18 and various functional layers.
(a) (anode layer)/hole injection layer/light-emitting layer/(cathode layer)
(b) (anode layer)/hole injection layer/light emitting layer/electron injection layer/(cathode layer)
(c) (anode layer)/hole injection layer (or hole transport layer)/light emitting layer/electron transport layer/electron injection layer/(cathode layer)
(d) (anode layer)/hole injection layer/hole transport layer/light-emitting layer/(cathode layer)
(e) (anode layer)/hole injection layer/hole transport layer/light-emitting layer/electron injection layer/(cathode layer)
(f) (anode layer)/hole injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer/(cathode layer)
(g) (anode layer)/light emitting layer/electron transport layer (or electron injection layer)/(cathode layer)
(i) (anode layer)/light emitting layer/electron transport layer/electron injection layer/(cathode layer)
The symbol "/" means that the layers on both sides of the symbol "/" are joined together.

The number of light-emitting layers included in the device function unit 16 may be one, or two or more. In any one of the layer configurations of the above configuration examples (a) to (i), if the laminate disposed between the anode layer 14 and the cathode layer 18 is referred to as [structural unit I], two layers As a configuration of the device function section 16 having a light emitting layer of , there is a layer configuration shown in (j) below. The layer configurations of the two structural units I may be the same or different.
(j) (anode layer)/[structural unit I]/charge generating layer/[structural unit I]/(cathode layer)

The charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include thin films containing vanadium oxide, ITO, molybdenum oxide, and the like.

When "[structural unit I]/charge generation layer" is set to [structural unit II], the layer structure shown in (k) below can be given as a structure of an organic EL device having three or more light-emitting layers.
(k) (anode layer)/[structural unit II]x/[structural unit I]/(cathode layer)
The symbol "x" represents an integer of 2 or more, and "[structural unit II]x" represents a laminate in which [structural unit II] is stacked in x stages. A plurality of structural units II may have the same or different layer configurations.

The device function section 16 may be configured by directly stacking a plurality of light emitting layers without providing the charge generation layer.

[Cathode layer]
A cathode layer 18 is provided on the device function portion 16 . The optimum thickness of the cathode layer 18 differs depending on the material used, and is set in consideration of electrical conductivity, durability, and the like. The thickness of the cathode layer 18 is generally 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 50 nm to 500 nm.

The material of the cathode layer 18 is such that the light from the device function portion 16 (specifically, the light from the light emitting layer) is reflected by the cathode layer 18 and travels to the anode layer 14 side. Materials that are highly reflective to light (particularly visible light) from the layer are preferred. Examples of materials for the cathode layer 18 include aluminum and silver. As the cathode layer 18, a transparent conductive electrode made of a conductive metal oxide, a conductive organic substance, or the like may be used.

The organic EL device 10 may include a sealing member for preventing deterioration of the device functional section 16 due to moisture or the like. A sealing member may be provided on the cathode layer 18 to seal at least the device functional portion 16 . In embodiments in which the organic EL device 10 includes a sealing member, for example, portions of the anode layer 14 and the cathode layer 18 may be drawn out from the sealing member for external connection.

Next, an example of a method for manufacturing the organic EL device 10 will be described. When manufacturing the organic EL device 10, the anode layer 14 is formed on the substrate 12 (anode layer forming step). After that, the device function portion 16 is formed on the anode layer 14 (device function portion forming step). Subsequently, a cathode layer 18 is formed on the device function portion 16 (cathode layer forming step). Through such steps, the organic EL device 10 is manufactured.

In a form in which the organic EL device 10 has the sealing member, a sealing step of sealing the device functional portion 16 with the sealing member may be performed after the cathode layer forming step.

When a long substrate 12, for example, is used for manufacturing the organic EL device 10, for example, a plurality of device formation regions are virtually set on the long substrate 12, and the anode layer 14 and the device function are formed for each device formation region. A portion 16 and a cathode layer 18 are formed. As a result, since the organic EL device 10 is formed for each device formation region, a plurality of organic EL devices 10 can be manufactured by singulating the long substrate 12 for each device formation region.

In the form in which the elongated substrate 12 is flexible, at least one of the anode layer forming process, the device functional part forming process, and the cathode layer forming process may be carried out, for example, by a roll-to-roll method. In a form in which the device function section 16 has a plurality of functional layers, at least one of the steps of forming each of the plurality of functional layers may be performed in a roll-to-roll manner.

Next, the method for manufacturing the organic EL device 10 will be described more specifically.

In the manufacture of the organic EL device 10, at least one of the anode layer 14, one or more functional layers of the device function section 16, and the cathode layer 18 (hereinafter, for convenience of explanation, referred to as "predetermined layer" ) is formed by an inkjet printing method using an inkjet printing device. When the predetermined layer is formed by the inkjet printing method in this way, the inkjet printing apparatus once manufactures the organic EL device 10 according to the manufacturing process of the organic EL device 10 described above, and then manufactures the next organic EL device 10. Wait until manufacturing.

That is, the method for manufacturing the organic EL device (electronic device) 10 includes a layer forming step of forming the predetermined layer by an inkjet printing method, and a waiting step of waiting the inkjet printing apparatus. The layer forming process and the standby process will be described.

[Layer forming process]
FIG. 2 and FIG. 3 are used for the case where the device function part 16 has an electron transport layer (functional layer) and the electron transport layer is formed by an inkjet printing method (that is, when the electron transport layer is the above-described predetermined layer). and explain. Hereinafter, for convenience of explanation, the coating film that will be the electron transporting layer is referred to as coating film 20 , and the electron transporting layer is referred to as electron transporting layer 22 .

FIG. 2 is a schematic diagram for explaining the schematic configuration of the inkjet printer 24 used in the layer forming process. FIG. 3 is a drawing for explaining the layer forming process. In FIG. 3, the elongate base substrate 26 on which the electron transport layer 22 is formed is schematically illustrated as a film (or plate) member. The base substrate 26 is the substrate 12 provided with the anode layer 14 and at least one functional layer provided between the electron transport layer 22 and the anode layer 14 in the device functional portion 16 . In a mode in which layers other than the electron transport layer 22 are formed in the layer forming process, the base substrate 26 is a substrate including the substrate 12 and at least one layer provided on the substrate 12 by the layer forming process.

The inkjet printing device 24 includes an inkjet head 28, an ink supply section 30, and a control section 32, as shown in FIG. The control unit 32 controls the inkjet printing device 24 .

The inkjet head 28 extends in one direction. The inkjet head 28 is formed with a plurality of ink discharge ports 34 discretely arranged in one direction (the width direction of the base substrate 26), and piezoelectric elements 36 (for example, piezo element) is provided. The diameter of the ink ejection port 34 is, for example, 5 μmφ to 200 μmφ. For example, the wetted parts (piezoelectric element 36, wiring part, etc.) inside the inkjet head 28 may be subjected to an insulating treatment (for example, a process of covering the wetted parts with an insulator). When covering the piezoelectric element 36 with an insulating material, the insulating material may cover areas other than the connection between the piezoelectric element 36 and the wiring portion. Ink is ejected from the ink ejection port 34 by vibrating the piezoelectric element 36 . The amount of ink ejected from each of the plurality of ink ejection ports 34 (including the case where the ejection amount is 0) is controlled by the controller 32 .

As shown in FIG. 3 , the inkjet head 28 is arranged to face the surface of the base substrate 26 on which the electron transport layer 22 is formed, and the extending direction of the inkjet head 28 is the width direction (longitudinal direction) of the base substrate 26 . direction perpendicular to the direction).

By controlling the amount of ink ejected (including the case where the amount of ejection is 0) from each of the plurality of ink ejection ports 34 of the inkjet head 28 arranged as described above, the amount of ink ejected from the base substrate 26 is controlled by the control unit 32. It can be applied in a predetermined pattern on the layer forming area.

The ink supply section 30 supplies ink to the inkjet head 28 . The ink supply unit 30 includes, for example, a tank that stores ink. The ink supply unit 30 and the inkjet head 28 are connected by a pipe 38 for circulating ink therebetween. That is, the inkjet printing device 24 is a circulation type inkjet device. A flow control unit 40 such as a pump is provided in the pipe 38 . By controlling the flow rate adjustment section 40 by the control section 32 , the flow rate of the ink supplied to the inkjet head 28 can be adjusted, and the ink circulates between the ink supply section 30 and the inkjet head 28 .

The inkjet printing device 24 may include multiple inkjet heads 28 . In this case, the plurality of inkjet heads 28 are arranged along the longitudinal direction of the underlying substrate 26 . In a configuration in which the inkjet printing device 24 having a plurality of inkjet heads 28 is of a circulation type, the ink may circulate between the plurality of inkjet heads 28 and the ink supply section 30 .

As shown in FIG. 3, in the layer forming process, the ink containing the material of the electron transport layer 22 is applied from the inkjet printing device 24 to the base substrate 26 (or the substrate 12) while the base substrate 26 is transported in its longitudinal direction. A coating film 20 is formed by coating on a region where a predetermined layer is to be formed. The ink containing the material of the electron transport layer 22 is, for example, an ink containing an aromatic hydrocarbon compound and an alkali metal salt or an alkaline earth metal salt. After that, the electron transport layer 22 is obtained by drying the coating film 20 in the drying device 42 . The drying device 42 may be, for example, a drying device using infrared rays, or may be one using other methods (hot air, hot plate, etc.). The drying device 42 may combine different drying methods.

Here, the case where the electron transport layer is the predetermined layer (the case where the layer forming step is included in the device functional portion forming step) has been described. However, at least one of the anode layer 14, the one or more functional layers included in the device function section 16, and the cathode layer 18 may be formed by the layer forming process. In other words, the layer forming step may be included in at least one of the anode layer forming step and the cathode layer forming step.

The one or more functional layers of the device function section 16 and the layers other than the predetermined layer among the anode layer 14 can be formed by, for example, a dry film forming method, a plating method, a coating method other than the inkjet printing method, or the like. Dry film forming methods include, for example, a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, and the like. Examples of coating methods other than inkjet printing include slit coating, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, spray coating, screen printing, flexographic printing, An offset printing method, a nozzle printing method, and the like can be mentioned.

When the cathode layer 18 is a layer other than the predetermined layer, the cathode layer 18 can be formed by coating methods such as a slit coater method, a gravure printing method, a screen printing method, a spray coater method, a vacuum deposition method, a sputtering method, and a metal thin film. can be formed by a lamination method or the like of thermocompression bonding.

[Standby process]
In the standby step, ejection of ink from all the ink ejection ports 34 of the inkjet printer 24 is stopped. In the standby process, while power is supplied to the inkjet printing device 24, the voltage supply to the piezoelectric element 36 is cut off. Cutting off the voltage supply to the piezoelectric element 36 means that the voltage supplied to the piezoelectric element 36 is 0.5 V or less. In embodiments in which the inkjet printing device 24 is a circulating inkjet printing device, power supplied to the inkjet printing device 24 may cause the ink to circulate during the standby process. In the standby process, the inkjet printing device 24 is kept on standby for, for example, one hour or longer. In the standby process, the inkjet printer 24 may be on standby for one day or longer, three days or longer, or six days or longer, for example.

An example of the standby process is, as described above, for example, after the organic EL device 10 is once manufactured by performing the manufacturing process of the organic EL device 10 including the anode layer forming process, the device function part forming process, and the cathode layer forming process. , is a step of making the inkjet printer 24 wait until the next organic EL device 10 is manufactured by carrying out similar manufacturing steps.

In this case, the process of temporarily manufacturing the organic EL device 10 by carrying out the manufacturing process of the organic EL device 10 including the anode layer forming process, the device function part forming process and the cathode layer forming process is called a first device manufacturing process, Next, when the process of manufacturing the organic EL device 10 is called a second device manufacturing process, the organic EL device manufacturing method includes a first device manufacturing process, a standby process, and a second device manufacturing process. At least one of the anode layer forming process, the device functional portion forming process, and the cathode layer forming process included in the first device manufacturing process and the second device manufacturing process is the layer forming process.

The standby process is not limited to the case where the inkjet printer 24 is kept on standby between the first and second device manufacturing processes. For example, when manufacturing the organic EL device 10 by performing the anode layer forming step, the device functional portion forming step, and the cathode layer forming step (in other words, when performing each of the first and second device manufacturing steps) , and the case where the inkjet printing device 24 is put on standby due to troubles, condition changes, inspections, etc. of other devices on the production line.

In the standby process, the voltage supply to the piezoelectric element 36 is cut off as described above. Therefore, substantially no electric field is generated in the vicinity of the piezoelectric element 36 as compared with the case where the voltage is applied to the piezoelectric element 36 . Therefore, even if ink exists in the vicinity of the piezoelectric element 36, the components contained in the ink are prevented from aggregating due to electrical force and from solidifying due to chemical reactions caused by the electric field. . As a result, problems (for example, clogging of the ink ejection port 34) due to the aggregation and solidification of the ink can be prevented. Prevention of the trouble is not limited to the trouble caused by performing the standby process once. That is, in the standby process of the present embodiment, as described above, the aggregation and solidification of the ink itself can be suppressed in the standby process. Therefore, for example, even if the waiting process is repeated, accumulation of agglomerated or solidified ink can be prevented, and the above problems can be prevented. As a result, when the layer forming step is performed again after the standby step, the layer forming step can be performed without performing the work to solve the problem, or at least the number of times of work to solve the problem can be reduced. The production efficiency of the organic EL device 10 is improved.

In the standby process, since the voltage supply to the piezoelectric element 36 is cut off, the piezoelectric element 36 is not preliminarily vibrated. Therefore, the meniscus shape of the ink may differ from the desired state. Therefore, in the method for manufacturing the organic EL device 10 including the standby step, in the layer forming step, before forming a predetermined layer (for example, an electron transport layer) by ejecting ink from an inkjet device, It is preferable to perform the step of ejecting the ink once. As a result, even if the layer forming process is performed again after the standby process, the ink can be ejected in a desired meniscus shape.

Ejecting the ink outside the formation region is not limited to the case where the ink is ejected outside the formation region of the predetermined layer on the underlying substrate 26. For example, when the inkjet head 28 is movably installed, the underlying substrate It also includes the case where the ink is once ejected at a location other than 26 .

When the ink ejected from the inkjet printing device 24 is an ink for forming the electron transport layer 22 (for example, when it is an ink containing an aromatic hydrocarbon compound and an alkali metal salt or an alkaline earth metal salt) ), if voltage is supplied to the piezoelectric element 36 when the ink jet printer 24 is put on standby, the aggregation and solidification described above are likely to occur. Therefore, the manufacturing method of the organic EL device (electronic device) 10 including the waiting step of interrupting the voltage supply to the piezoelectric element when the inkjet printing device 24 is put on standby is such that the ink used in the layer forming step causes the electron transport layer 22 to It is effective when it is an ink for forming. For the same reason, the manufacturing method of the organic EL device (electronic device) 10 including the above-described standby step can be used when the ink used in the layer forming step is an ink for forming a hole injection layer or a hole transport layer. It is valid.

Next, the effect of interrupting the voltage supply to the piezoelectric element 36 in the standby process will be further described with reference to experimental examples. However, the present invention is not limited to the following experimental examples.

[Experimental example 1]
In Experimental Example 1, a circulation-type inkjet printer was used. In the inkjet device of Experimental Example 1, an inkjet head was used in which the electrodes for supplying voltage to the piezoelectric elements were not insulated. The inkjet head was formed with a plurality of ink ejection openings. In Experimental Example 1, the ink for the electron transport layer was discharged from the inkjet printer onto the transported water absorbent sheet. The ink contained an aromatic hydrocarbon compound and an alkali metal salt.

If the ink ejection port is clogged, the ink will not be ejected, so there will be areas where the water absorbent sheet does not absorb the ink, and these areas will appear as streaks. It was confirmed that no streaks were formed on the water-absorbent sheet by the initial ejection of the ink (that is, the ink ejection openings were not clogged).

After that, power was supplied to the inkjet printing device to circulate the ink, and the inkjet printing device was made to stand by while cutting off the voltage supply to the piezoelectric element. That is, the standby step was performed. After the standby process was performed, ink was ejected onto the water absorbent sheet from the inkjet printer, and the clogging of the ink ejection openings was confirmed by the presence or absence of streaks on the water absorbent sheet. In Experimental Example 1, the standby and ink ejection were repeated every day. In Experimental Example 1, the change over time of the inkjet printing apparatus was observed with the same inkjet head every day for 10 days.

[Experimental example 2]
In Experimental Example 2, a circulating inkjet printer was used. In the inkjet device of Experimental Example 2, the same experiment as in Experimental Example 1 was performed, except that an inkjet head in which the piezoelectric element was insulated was used.

[Experimental example 3]
Experimental Example 3 is a comparative experiment to Experimental Example 1. In Example 3, the same type of inkjet printing apparatus as in Example 1 was used. In Experimental Example 3, the same experiment as in Example 1 was performed, except that a voltage was supplied to the piezoelectric element to pre-vibrate the piezoelectric element when the inkjet printing apparatus was put on standby.

[Comparison of the results of Experimental Examples 1, 2 and 3]
In Experimental Example 3 in which a voltage was supplied to the piezoelectric element in the standby process, streaks were observed on the water absorbent sheet when ink was ejected from the ink jet printing apparatus to the water absorbent sheet after repeating the one-day standby four times. The streaks increased as the number of days of follow-up observation increased. That is, in Experimental Example 3, aggregation and solidification of the ink occurred while the inkjet printing apparatus was on standby, and this was accumulated, and it is considered that clogging of the ink ejection port occurred when the inkjet apparatus was on standby four times.

On the other hand, in Experimental Examples 1 and 2, regardless of the number of days elapsed, even when ink was ejected onto the water absorbent sheet from the ink jet printing apparatus after standby, the streaks did not occur on the water absorbent sheet.

Therefore, from the results of Experimental Examples 1, 2, and 3, it was found that clogging of the ink ejection port (in other words, ink It can be understood that it is possible to more reliably prevent aggregation and solidification of

Experimental examples 1 and 3 were conducted under the same conditions except for the presence or absence of voltage application to the piezoelectric element in the standby process. Therefore, it is considered that the clogging of the ink ejection port in Experimental Example 3 is caused by the fact that an electric field is generated in the vicinity of the piezoelectric element by applying voltage to the piezoelectric element in the standby process. Therefore, if the piezoelectric element is insulated, clogging of the ink discharge port is less likely to occur. Therefore, even when the voltage supply to the piezoelectric element is cut off and the inkjet printing apparatus is put on standby, the piezoelectric element is insulated, so that problems caused by aggregation and solidification of the ink during the standby process can be further prevented. It can be understood that it can be prevented.

Various embodiments of the present invention have been described above. However, the present invention is not limited to the various illustrated embodiments, but is indicated by the scope of the claims, and is intended to include all modifications within the meaning and scope of equivalents of the scope of the claims. be done.

For example, when the method for manufacturing an electronic device (for example, an organic EL device) includes the layer forming step and the standby step described in the above embodiment, the inkjet printing apparatus includes an ejection step of ejecting ink and an ejection step of ejecting ink from the inkjet printing apparatus. is stopped and the inkjet printer is driven by a drive method including a waiting step for waiting the inkjet printing device. Furthermore, in the standby process included in this driving method, power is supplied to the inkjet printing device and the voltage supply to the piezoelectric element of the inkjet head is interrupted. Therefore, in the above embodiments, one aspect of the present invention has been described by focusing on the method of manufacturing an electronic device, but the present invention also relates to a method of driving an inkjet printing apparatus. In the driving method of the inkjet printing apparatus, since the voltage supply to the piezoelectric element is interrupted in the standby process, it is possible to prevent clogging of the ink ejection openings in the standby process.

The standby period of the inkjet printer in the standby process is not limited to one day as exemplified in Experimental Examples 1 and 2. As described above, the standby period of the inkjet printing apparatus in the standby process may be, for example, one hour or longer. Depending on the type of ink and the size of the ink ejection port, even if the standby process is about an hour (or repeated), if voltage is supplied to the piezoelectric element during the standby process, ink may aggregate or solidify. It is because there is a nature.

Although the first electrode layer is the anode layer and the second electrode layer is the cathode layer, the first electrode layer may be the cathode layer and the second electrode layer may be the anode layer.

The present invention can also be applied to manufacturing organic electronic devices other than organic EL devices, such as organic solar cells, organic photodetectors, and organic transistors. Furthermore, the present invention can also be applied to the manufacture of electronic devices in which all functional layers of the device functional portion are made of inorganic materials.

DESCRIPTION OF SYMBOLS 10... Organic electroluminescent device (electronic device), 12... Substrate, 14... Anode layer (1st electrode layer), 18... Cathode layer (2nd electrode layer), 24... Inkjet printing apparatus, 28... Inkjet head.

Claims (6)

An electronic device for manufacturing an electronic device comprising a first electrode layer and a second electrode layer provided on a substrate and one or more functional layers provided between the first electrode layer and the second electrode layer A device manufacturing method comprising:
a layer forming step of forming at least one layer of the first electrode layer, the one or more functional layers, and the second electrode layer by an inkjet printing method using an inkjet printing apparatus;
A waiting step of stopping ejection of ink from the inkjet printing device and causing the inkjet printing device to stand by;
with
In the standby step, power is supplied to the inkjet printing device, and voltage supply to the piezoelectric element of the inkjet head of the inkjet printing device is interrupted;
The inkjet printing device is a circulating inkjet device that circulates the ink between an ink supply unit and an inkjet head that ejects the ink,
In the standby step, the ink is circulated;
The piezoelectric element included in the inkjet head is insulated,
A method of manufacturing an electronic device. In the layer forming step, before ejecting ink from the inkjet printing device to form the at least one layer, the ink is ejected from the inkjet printing device outside the formation region of the at least one layer.
A method of manufacturing an electronic device according to claim 1 . The ink ejected from the inkjet printing device is an ink for forming a hole injection layer, a hole transport layer, or an electron transport layer.
3. A method of manufacturing an electronic device according to claim 1 or 2. The ink ejected from the inkjet printing device contains an aromatic hydrocarbon compound and an alkali metal salt or an alkaline earth metal salt.
A method for manufacturing an electronic device according to any one of claims 1 to 3. In the standby step, the inkjet printing device is kept on standby for one hour or more;
A method for manufacturing an electronic device according to any one of claims 1 to 4 . an ejection step of ejecting ink from an inkjet printing device;
A waiting step of stopping ejection of the ink from the inkjet printing device and causing the inkjet printing device to stand by;
has
In the standby step, power is supplied to the inkjet printing device, and voltage supply to the piezoelectric element of the inkjet head of the inkjet printing device is interrupted;
The inkjet printing device is a circulating inkjet device that circulates the ink between an ink supply unit and an inkjet head that ejects the ink,
In the standby step, the ink is circulated;
The piezoelectric element included in the inkjet head is insulated,
A method of driving an inkjet printer.

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