Laminate and laminate production method

Abstract

Provided is a laminate 1a which includes: a substrate layer 10; a layer 121 including first conductive particles on the substrate layer 10; and a layer 122 including second conductive particles on the layer 121 including the first conductive particles. The average particle diameter of the first conductive particles is larger than the average particle diameter of the second conductive particles.

Description

Laminate and method for manufacturing laminate

[0001] The present invention relates to a laminate and a method for manufacturing the laminate.

[0002] Patent Document 1 discloses a technology for obtaining conductive ITO (indium tin oxide) particles by adding an indium source and a tin source to a solution in which a hydroxide of a quaternary ammonium ion is dissolved in a reducing organic solvent, causing a reaction, and then heating the solution in an autoclave to mature it under autogenous pressure.

[0003] Patent No. 5706797

[0004] A first aspect of the present invention is a laminate comprising a substrate layer, a layer containing first conductive particles on the substrate layer, and a layer containing second conductive particles on the layer containing the first conductive particles, wherein the average particle diameter of the first conductive particles is larger than the average particle diameter of the second conductive particles.

[0005] A second aspect of the present invention is a laminate including a support layer, a layer containing second conductive particles on the support layer, and a layer containing first conductive particles on the layer containing the second conductive particles, wherein the average particle diameter of the second conductive particles is smaller than the average particle diameter of the first conductive particles.

[0006] A third aspect of the present invention is a method for manufacturing a laminate including a first layer and a second layer, the method comprising the steps of: supplying a first solution containing first conductive particles onto a substrate layer or a support layer and drying the solvent contained in the first solution to form the first layer; and supplying a second solution containing second conductive particles onto the first layer and drying the solvent contained in the second solution to form the second layer, wherein the first conductive particles and the second conductive particles have different average particle diameters.

[0007] Fig. 1 is a conceptual diagram showing an example of a laminate according to this embodiment. Fig. 2 is a conceptual diagram showing an example of an EL device using the laminate according to this embodiment. Fig. 3 is a conceptual diagram showing an example of a solar cell using the laminate according to this embodiment. Fig. 4 is a conceptual diagram showing another example of a laminate according to this embodiment. Fig. 5 is a conceptual diagram showing another example of an EL device using the laminate according to this embodiment. Fig. 6 is a conceptual diagram showing another example of a solar cell using the laminate according to this embodiment.

[0008] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. In the drawings, the same elements are given the same reference numerals, and duplicate explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0009] <Laminate 1> A first aspect of the laminate according to this embodiment is a laminate including a substrate layer, a first conductive layer containing first conductive particles on the substrate layer, and a second conductive layer containing second conductive particles on the first conductive layer containing the first conductive particles, wherein the average particle diameter of the first conductive particles is larger than the average particle diameter of the second conductive particles. Such a laminate can suppress contact resistance and interface resistance, and therefore can be suitably used as a component for electroluminescence (EL) devices, solar cells, and the like.

[0010] FIG. 1 is a conceptual diagram showing an example of a laminate according to this embodiment.

[0011] The laminate 1a includes a first conductive layer 121 containing first conductive particles and a second conductive layer 122 containing second conductive particles, which are formed in this order on a substrate layer 10. The average particle diameter of the first conductive particles is larger than the average particle diameter of the second conductive particles. That is, the laminate 1a includes a conductive layer 12 formed on a substrate layer 10.

[0012] The average particle size referred to here is the average particle size of primary particles, and is calculated by dynamic light scattering.

[0013] The average particle size of the first conductive particles is preferably 40 to 100 nm, more preferably 40 to 70 nm, and even more preferably 40 to 60 nm.

[0014] The average particle size of the second conductive particles is preferably 5 to 30 nm, more preferably 5 to 20 nm, and even more preferably 5 to 15 nm.

[0015] The ratio of the average particle size of the first conductive particles to the average particle size of the second conductive particles is preferably 1.3 to 20, more preferably 1.3 to 14, and even more preferably 1.3 to 12.

[0016] The thickness of the first conductive layer is preferably 10 to 1000 nm, more preferably 10 to 100 nm, and even more preferably 10 to 20 nm.

[0017] The thickness of the second conductive layer is preferably 10 to 1000 nm, more preferably 10 to 100 nm, and even more preferably 10 to 20 nm.

[0018] Examples of the types of the first conductive particles and the second conductive particles (hereinafter, these may be collectively referred to as "conductive particles") include tin-doped indium oxide (ITO) particles, antimony-doped tin oxide (ATO) particles, phosphorus-doped tin oxide (PTO) particles, tin oxide (TO) particles, titanium oxide particles, zinc oxide particles, and other white conductive particles and colorless conductive particles. These may be used alone or in combination of two or more types. Among these, the conductive particles are preferably one or more types selected from the group consisting of ITO particles, ATO particles, PTO particles, and TO particles, and ITO particles are more preferred.

[0019] The material of the substrate layer 10 is not particularly limited, and materials that can be used as substrates for the above-mentioned EL devices, solar cells, and the like can be used. In particular, when a manufacturing method is used in which a dispersion liquid described below is applied to the substrate layer 10, material restrictions are relaxed, making it possible to use a thin, highly flexible film substrate (sometimes called a sheet substrate). Furthermore, continuous production such as roll-to-roll production is also possible. From this perspective, examples of materials that can be used for the substrate layer 10 include glass, silicon, aluminum, alumina, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), and cellulose acetate propionate (CAP).

[0020] Semiconductors and other components used in components such as EL devices and solar cells are required to have low resistance. In this regard, the laminate 1a according to this embodiment has a structure in which first conductive particles with a large average particle diameter are stacked on the substrate layer 10, thereby reducing the number of contact points between the substrate layer and the conductive layer, thereby reducing the interfacial resistance at the interface between the substrate layer and the conductive film. Furthermore, within the conductive film, first conductive particles with a small average particle diameter are stacked on top of first conductive particles with a large average particle diameter, thereby increasing the contact area between the particles and reducing the contact resistance between the conductive particles. In this way, the laminate 1a can reduce the interfacial resistance and contact resistance, thereby exhibiting high conductivity.

[0021] It is preferable that the first conductive particles, the second conductive particles, or both of them satisfy the relationship represented by the following formula (1): 16×S / P ２ ≦0.330 (1) (wherein S represents the particle area in the TEM photograph, and P represents the circumferential length of the particle.)

[0022] The particle area S and perimeter P in formula (1) are the area and perimeter of a particle in a TEM photograph, and can be determined, for example, according to the following method.

[0023] First, the TEM photograph of the conductive particles is processed using the image processing software "ImageJ 1.5K." For example, the image of the target is first captured and converted to an 8-bit grayscale. Next, to make the scale of one pixel correspond to the actual image, the number of nm per pixel is set using "Set Scale."

[0024] Next, to clarify the particle shapes, "Enhance Contrast" is used to set Saturated Pixels to approximately 20-40%. This value also affects the contrast of the entire image, so it should be adjusted as appropriate, but for example, the degree to which the particle outlines are clear can be used as a reference. Furthermore, binarization is performed using "Threshold" to separate the particle shapes from other parts, and an algorithm called "Moments" can be used to set the threshold.

[0025] Then, "Analyze Particles" was selected to measure the particle shape. Contamination and background noise can be eliminated by setting "Size (Pixels^2)" to 1000-Infinity during measurement. Focusing on "Area" and "Perim." from the obtained results, these can be used to represent the particle area S and the particle perimeter P in the TEM photograph, respectively.

[0026] The value of the particle area S in this embodiment is not particularly limited, and is, for example, 100 to 4500 nm ２ 200 to 4300 nm ２ The value of P is not particularly limited, and may be, for example, 100 to 1200 nm, or 120 to 1000 nm.

[0027] The upper limit of the value of the left side of formula (1) may be 0.330 or less, preferably 0.300 or less, more preferably 0.280 or less, even more preferably 0.260 or less, and even more preferably 0.250 or less. By being in this range, the particle shape can be a particle shape that is significantly deformed from a substantially rectangular parallelepiped shape. In addition, the lower limit of the value of the left side of formula (1) is not particularly limited, and may be greater than 0, for example, 0.040 or more, 0.060 or more, 0.070 or more, or 0.100 or more.

[0028] The conductive particles according to this embodiment can be uniformly finely divided and highly dispersible, and can also meet the requirements for materials of various transparent electrodes, such as low resistance, high transmittance, and low turbidity (haze).

[0029] Conventional conductive particles such as ITO particles are synthesized by the gel-sol method, and have a roughly rectangular parallelepiped shape. In the gel-sol method, nucleation and growth reactions occur within the gel network, so ITO particles produced by the gel-sol method have a rectangular parallelepiped shape that reflects their crystalline phase and have high crystallinity.

[0030] When producing a conductive film using conventional conductive particles with a roughly rectangular parallelepiped shape, if the conductive particles are arranged so that their surfaces are in contact with each other, the film's filling rate will theoretically be 100%. Therefore, it was thought that it would be preferable for the conductive particles to have a rectangular parallelepiped single-crystal structure. However, after extensive research, the inventors discovered that this does not actually occur, and that the particles are randomly packed, resulting in point or linear contact between each other. Such an arrangement results in fewer conductive paths and higher resistance when used as a transparent conductive film. Furthermore, poor dispersibility leads to agglomeration of particles, resulting in a lower filling rate and loss of film smoothness. The inventors believed that conventional conductive particles have room for improvement in this respect.

[0031] The inventors further investigated the macroscopic state of conductive particles. As a result, the conductive particles of this embodiment can achieve the above-mentioned effects by satisfying the relationship of formula (1). Although the exact function and effect is unclear, it is believed that this is because the maximum contact area is reduced while maintaining high crystallinity, resulting in good dispersibility in the liquid when prepared as a dispersion (however, the functions and effects of this embodiment are not limited to these).

[0032] The method for preparing the conductive particles is not particularly limited, and any known method can be used as appropriate. Here, the case of ITO particles will be described as an example.

[0033] Regarding the component composition of the ITO particles, the molar ratio of the Sn content to the In content (Sn / In) is not particularly limited, but from the viewpoints of crystal synthesis and conductivity, it is preferably 3.5 to 24, more preferably 3.7 to 23.5, and even more preferably 4 to 23.

[0034] Furthermore, in this embodiment, when ITO particles satisfying the above-described formula (1) are used, it is preferable to manufacture them by the following method, rather than the gel-sol method: That is, it is preferable that the manufacturing method includes: (a) a reaction step of obtaining ITO particles by reacting in a solution containing 0.09 to 0.9 M (M = mol / L) of an In salt, 0.01 to 0.2 M (M = mol / L) of an Sn salt, a basic compound, and a solvent at 190 to 200°C for 12 to 120 hours; and (b) a step of washing the ITO particles.

[0035] The concentration of the In salt in the reaction solution is preferably 0.09 to 0.9 M, and more preferably 0.09 to 0.45 M. The concentration of the Sn salt in the reaction solution is preferably 0.01 to 0.2 M, and more preferably 0.01 to 0.05 M.

[0036] The concentration of the In salt is preferably 4.5 to 9 times, and more preferably 5 to 9 times, the molar concentration of the Sn salt. By carrying out the particle synthesis reaction at such metal source concentrations, the ITO particles according to this embodiment can be synthesized more easily in one pot.

[0037] The In salt is not particularly limited, and any known In salt can be used as a raw material for ITO. For example, InCl ３ metal salts such as In ２ (C ２ O ４ ) ３ , In(NO ３ ) ３ , In ２ (SO ４ ) ３ and hydrates thereof. Among these, anhydrous salts and metal salts are preferred, metal salts are more preferred, and InCl ３ is more preferred.

[0038] The Sn salt is not particularly limited, and any known Sn salt as a raw material for ITO can be used. For example, SnCl ２ , SnCl ４ , Sn ２ (C ２ O ４ ) ３ , Sn(NO ３ ) ２ , SnSO ４ , InCl ３ metal salts such as In ２ (C ２ O ４ ) ３ , In(NO ３ ) ３ , In ２ (SO ４ ) ３ and hydrates thereof. Among these, anhydrous salts and metal salts are preferred, metal salts are more preferred, and SnCl ２ , SnCl ４ is more preferred.

[0039] The basic compound is not particularly limited as long as it can neutralize the reaction solution and precipitate an In—Sn hydroxide (neutralization coprecipitation). Known basic compounds can be used. Examples include tetramethylammonium hydroxide (TMAH) and sodium hydroxide.

[0040] The concentration of the basic compound in the reaction solution is not particularly limited, but is preferably 1 to 2 M, more preferably 1.5 to 1.7 M, from the viewpoint of particle synthesis.

[0041] The solvent may be any solvent capable of dissolving the In salt, Sn salt, basic compound, and other additives used as needed. Known solvents may be used, and preferred examples include water and alcohols such as methanol, ethanol, and isopropanol.

[0042] (a) In the reaction step, other additives may be added as needed within a range that does not impair the effects of this embodiment.

[0043] The reaction time in the (a) reaction step is preferably 12 to 120 hours, more preferably 24 to 72 hours.

[0044] (a) The reaction temperature in the reaction step is preferably 190 to 200°C.

[0045] The reaction step (a) may be carried out in an open system, but it is preferable to use an autoclave, which can promote the formation of an indium hydroxide-tin hydroxide coprecipitate in the reaction system.

[0046] The mechanism by which ITO particles satisfying the relationship expressed by formula (1) are obtained by the above-mentioned manufacturing method is unclear, but it is thought that factors such as controlling the concentration of metal salt in the reaction system (M = mol / L), reaction temperature, and reaction time may have an effect. While controlling the shape of monodispersed particles can be controlled by the number of nuclei generated in the system and the amount of substance present therein, it is thought that it is necessary to maintain the particles in the gel network and allow further heterogeneous nucleation to occur. Therefore, it is thought that it is best to increase the concentration of the metal source and use a small amount of base relative to the metal source. This allows the concentration of metal oxide precursor capable of nucleation to be maintained for a long period of time. It is thought that synthesis is possible by combining the above-mentioned conditions. (However, the effects of this embodiment are not limited to these.)

[0047] To produce ITO particles that satisfy the relationship expressed by formula (1), it is preferable to increase the concentration of the metal source and to use a base concentration that is relatively low relative to the metal source. This allows heterogeneous nucleation to proceed on the generated nuclei, rather than allowing particle growth after the initial nucleation reaction, and as a result, ITO particles that satisfy the relationship expressed by formula (1) can be synthesized.

[0048] In this embodiment, a centrifugation step is preferably carried out between the (a) reaction step and the (b) washing step, and the centrifugation step is preferably carried out at 14,000 rpm for 10 minutes.

[0049] In the step (b) of washing the ITO particles, washing is preferably carried out using water, alcohols such as ethanol, etc. When washing with water, it is preferable to use distilled water or pure water such as ion-exchanged water (IEW). It is also preferable to wash the dispersion by treating it with an ultrasonic cleaner.

[0050] In addition, although a freeze-drying step and a reduction baking step are conventionally performed after the reaction step, these steps do not have to be performed in this embodiment. From this viewpoint, it is particularly preferable not to perform a baking step after step (b). This prevents aggregation of the ITO particles and maintains a monodispersed state in the dispersion medium.

[0051] The laminate 1a can be used as a low-resistance electronic component, and can be used as an EL device or a solar cell.

[0052] FIG. 2 is a conceptual diagram showing an example of an EL device using the laminate according to this embodiment.

[0053] In the EL device A, a hole transport layer 20, a light-emitting layer 30, an electron transport layer 40, and a cathode 50 are formed in this order on the second conductive layer 122 of the laminate 1a. The conductive layer 12 functions as an anode. The anode (conductive layer 12) and the cathode 50 are connected to a driving power source.

[0054] When a voltage is applied from a driving power source to the EL device A, the hole transport layer 20 and the electron transport layer 40 transport holes and electrons, respectively, which then combine in the light-emitting layer 30, thereby emitting light. The light from the light-emitting layer 30 is extracted through the light-transmitting substrate layer 10 and is displayed externally.

[0055] The substrate layer 10 is a light-transmitting substrate, and may be, for example, a glass substrate, or a film substrate such as a PET substrate or a PEN substrate.

[0056] The conductive layer 12 functions as a transparent electrode, and for example, an ITO electrode, a graphene electrode, or the like can be used.

[0057] The hole transport layer 20 may be made of, for example, PEDOT:PSS.

[0058] The light-emitting layer 30 is made of, for example, Alq ３ (tris-(8-hydroxyquinolinato)aluminum) and the like can be used.

[0059] The electron transport layer 40 may be made of, for example, 2-[4-(9,10-Di-naphthalen-2-yl-anthracen-2-yl)-phenyl]-1-phenyl-1H-benzoimidazole.

[0060] The cathode 50 can be made of a metal such as Cu.

[0061] Although not shown, an adjustment layer may be provided between the hole transport layer 20 and the conductive layer 12 as needed to reduce the difference in work function with the hole transport layer 20 .

[0062] FIG. 3 is a conceptual diagram showing an example of a solar cell using the laminate according to this embodiment.

[0063] In the solar cell B, an electron transport layer 60, an active layer 70, a hole transport layer 80, and an anode 90 are formed in this order on the second conductive layer 122 of the laminate 1a. The conductive layer 12 functions as a cathode.

[0064] Solar cell B receives light on the side of the light-transmitting substrate layer 10, and is excited when the light strikes the active layer 70, generating electrons and holes that are transported by the electron transport layer 60 and the hole transport layer 80, respectively, and extracted by the cathode (conductive layer 12) and the anode 90. Electric current can then be extracted from an external circuit (not shown) connected to the cathode (conductive layer 12) and the anode 90.

[0065] The substrate layer 10 is a light-transmitting substrate, and may be, for example, a glass substrate, or a film substrate such as a PET substrate or a PEN substrate.

[0066] The conductive layer 12 functions as a transparent electrode, and may be made of, for example, ITO, ATO (antimony-doped tin oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide), or the like.

[0067] The electron transport layer 60 is, for example, LiF ２ , TiO ２ etc. can be used.

[0068] The active layer 70 is, for example, C ６０ , CuPc (copper phthalocyanine), etc. can be used.

[0069] The cathode 50 may be made of, for example, Al, Cu, or the like.

[0070] The hole transport layer 80 is made of, for example, PEDOT:PSS, V ２ O ５ , MoO ３ etc. can be used.

[0071] <Laminate 2> A second aspect of the laminate according to this embodiment is a laminate including a support layer, a layer containing second conductive particles on the support layer, and a layer containing first conductive particles on the layer containing second conductive particles, wherein the average particle diameter of the second conductive particles is smaller than the average particle diameter of the first conductive particles. Such a laminate can suppress contact resistance and interface resistance, and therefore can be suitably used as a component for an EL device, a solar cell, or the like.

[0072] FIG. 4 is a conceptual diagram showing another example of the laminate according to the present embodiment.

[0073] In laminate 1b, second conductive layer 122 containing second conductive particles and first conductive layer 121 containing first conductive particles are formed in this order on support layer 14. The average particle diameter of the first conductive particles is larger than the average particle diameter of the second conductive particles (the average particle diameter of the second conductive particles is smaller than the average particle diameter of the first conductive particles). Unless otherwise specified, similar materials can be used as appropriate for materials that are the same as those in laminate 1b.

[0074] It is preferable that the first conductive particles or the second conductive particles, or both, satisfy the relationship represented by the above-mentioned formula (1).

[0075] The material of the support layer 14 is not particularly limited, but may be any of the above-mentioned materials that can be used as support layers for EL devices, solar cells, etc. Examples of materials for the support layer include PEDOT:PSS.

[0076] The average particle size of the first conductive particles is preferably 40 to 100 nm, more preferably 40 to 70 nm, and even more preferably 40 to 60 nm.

[0077] The average particle size of the second conductive particles is preferably 5 to 30 nm, more preferably 5 to 20 nm, and even more preferably 5 to 15 nm.

[0078] The ratio of the average particle size of the first conductive particles to the average particle size of the second conductive particles is preferably 1.3 to 20, more preferably 1.3 to 14, and even more preferably 1.3 to 12.

[0079] The thickness of the first conductive layer is preferably 10 to 1000 nm, more preferably 10 to 100 nm, and even more preferably 10 to 20 nm.

[0080] The thickness of the second conductive layer is preferably 10 to 1000 nm, more preferably 10 to 100 nm, and even more preferably 10 to 20 nm.

[0081] The laminate 1b according to this embodiment has a structure in which second conductive particles having a small average particle size are laminated on a support layer 14 having a finely uneven surface. This increases the contact area between the support layer 14 and the conductive layer 12, thereby reducing the interfacial resistance at the interface between the support layer 14 and the conductive layer 12. Furthermore, within the conductive layer 12, first conductive particles having a large average particle size are laminated on second conductive particles having a small average particle size, thereby increasing the contact area between the particles and reducing the contact resistance between the conductive particles. In this way, the laminate 1b can reduce the interfacial resistance and contact resistance, thereby exhibiting high conductivity.

[0082] FIG. 5 is a conceptual diagram showing another example of an EL device using the laminate according to this embodiment.

[0083] In EL device C, a substrate layer 10 is formed on the second conductive layer 122 of the laminate 1b, and a light-emitting layer 30, an electron transport layer 40, and a cathode 50 are formed in this order on a support layer 14. The conductive layer 12 functions as an anode, and the support layer 14 functions as a hole transport layer. The anode (conductive layer 12) and the cathode 50 are connected to a driving power source. Unless otherwise specified, the EL device C can use the same components as those of the above-mentioned EL device A.

[0084] When a voltage is applied from a driving power source to the EL device C, the hole transport layer (support layer 14) and the electron transport layer 40 transport holes and electrons, respectively, which then combine in the light-emitting layer 30, causing the EL device C to emit light. The light from the light-emitting layer 30 is extracted through the light-transmitting substrate layer 10 and displayed externally.

[0085] The support layer 14 may be any layer that functions as a hole transport layer, and the materials for the hole transport layer described above may be used.

[0086] The substrate layer 10 may be made of a material having light-transmitting properties, similar to the substrate layers described above.

[0087] FIG. 6 is a conceptual diagram showing another example of a solar cell using the laminate according to this embodiment.

[0088] In solar cell D, a substrate layer 10 is formed on the second conductive layer 122 of the laminate 1b, and an active layer 70, a hole transport layer 80, and an anode 90 are formed in this order on a support layer 14. The conductive layer 12 functions as a cathode, and the support layer 14 functions as an electron transport layer. Unless otherwise specified, solar cell D can use the same components as those of solar cell B described above.

[0089] The solar cell D receives light on the side of the light-transmitting substrate layer 10, and is excited when the light strikes the active layer 70, generating electrons and holes that are transported by the electron transport layer (support layer 14) and the hole transport layer 80, respectively, and extracted by the cathode (conductive layer 12) and the anode 90. Electric current can then be extracted from an external circuit (not shown) connected to the cathode (conductive layer 12) and the anode 90.

[0090] The support layer 14 may be any layer that functions as an electron transport layer, and the materials for the electron transport layer described above may be used.

[0091] The substrate layer 10 may be made of a material having light-transmitting properties, similar to the substrate layers described above.

[0092] <Method for manufacturing conductive film> According to this embodiment, a conductive film can be manufactured using the laminate described above. A preferred example of a method for manufacturing a conductive film including the first conductive layer and the second conductive layer described above includes the following steps: (1) supplying a first solution containing first conductive particles onto a substrate layer or a support layer, and drying the solvent contained in the first solution to form a first conductive layer; and (2) supplying a second solution containing second conductive particles onto the first layer, and drying the solvent contained in the second solution to form a second conductive layer, wherein the first conductive particles and the second conductive particles have different average particle diameters.

[0093] By forming two layers containing conductive particles with different average particle sizes on a substrate layer or a support layer, a conductive film with reduced contact resistance at the interface can be obtained.

[0094] The substrate layer and the support layer may be the same as those usable in the laminate described above.

[0095] The layer containing conductive particles can be formed by supplying a dispersion liquid in which the above-mentioned conductive particles are dispersed in a solvent, and then drying the solvent.

[0096] (Supply process)

[0097] As the step of supplying the dispersion onto the substrate layer or the support layer (supplying step), a method of applying or spraying a dispersion in which conductive particles are dispersed in a solvent can be employed.

[0098] The solvent for the dispersion is not particularly limited, but examples thereof include water, alcohols such as methanol, ethanol, and isopropyl alcohol, and mixed solvents thereof. Among these, water and alcohols are preferred, and water is more preferred. That is, the dispersion according to this embodiment can be suitably used as an aqueous dispersion.

[0099] The dispersion may contain other additives as required.

[0100] In particular, when ordinary conductive particles are dispersed in a solvent for a long period of time, a surfactant is required to prevent particle aggregation, but the dispersion liquid used in this embodiment can be a dispersion liquid in which conductive particles can be dispersed for a long period of time without adding a surfactant. Thus, the dispersion liquid according to this embodiment can be one that does not substantially contain a surfactant, i.e., a surfactant-free dispersion liquid.

[0101] The surfactant referred to here refers to a substance that has the function of adsorbing to the particle surface and making the particles dispersible in a dispersion medium, and specific examples include anionic surfactants, cationic surfactants, and nonionic surfactants.

[0102] In the dispersion, the ratio (volume ratio) of the conductive particles to the solvent is not particularly limited, but is preferably 40% or less. By setting the ratio in this range, the conductive particles can be stably monodispersed for a long period of time.

[0103] The dispersion method is not particularly limited, and may be a stirring method using a stirrer or the like, or an ultrasonic dispersion method using an ultrasonic bath or the like, or these may be used in combination. Of these, it is preferable to use an ultrasonic bath.

[0104] The dispersion liquid may be applied directly onto the substrate layer, or may be sprayed onto the substrate layer in the form of a mist, and may be applied under atmospheric pressure, reduced pressure, or vacuum, but is preferably applied under atmospheric pressure from the viewpoint of simplicity.

[0105] For example, when manufacturing an ITO film as a conductive film, the ITO film is a material with high conductivity and transparency, and is widely used as a transparent conductive material. Methods for manufacturing ITO films include sputtering and laser deposition, but these techniques make it difficult to form a uniform thin film on a flexible substrate layer, and the performance of ITO, which has excellent surface properties, is not fully utilized. Furthermore, the deposition process requires a large-scale facility configuration, and there is room for improvement in this regard as well.

[0106] In this regard, the dispersion according to this embodiment has high dispersibility and no sedimentation of components, so that simple coating techniques or mist deposition techniques can be used when forming an ITO thin film on a substrate layer. Furthermore, restrictions on the substrate material can be relaxed, making it possible to form a film on the flexible substrate described above. Furthermore, according to this embodiment, even when nano-level ITO particles (ITO nanoparticles) are formed, high crystallinity and monodispersity can be stably maintained, so that surface properties such as conductivity and transparency of the thin film can be controlled at a high level.

[0107] The method for producing the mist is not particularly limited, and any method for producing the dispersion liquid in a mist (atom) state can be used. Any known method can be used to produce the mist, such as a pressurized method, a rotating disk method, an ultrasonic method, an electrostatic method, an orifice vibration method, or a steam method. In this embodiment, since the dispersion liquid is an ITO particle dispersion, a physical method for producing the mist is preferred. This facilitates control of the liquid temperature and droplet size. Furthermore, treating the dispersion liquid as a mist provides high controllability and eliminates problems such as distortion during thin film formation, which are common in methods such as the sol-gel method, which involves supplying a liquid.

[0108] In the mist formation, the mist of the dispersion liquid can be carried to the subsequent contact step by using a carrier gas, such as an inert gas such as argon, helium, or nitrogen.

[0109] The mist generation may further include a step of homogenizing the mist using a mist trap and a retention step of providing a retention period (retention portion) for the mist.

[0110] In addition, examples of the spraying method include ultrasonic spraying, mist CVD, a Sonia source method, a hot wall method, etc. These methods can be selected in consideration of the film thickness of the conductive film to be formed on the substrate layer, the size of the droplets to be sprayed, etc.

[0111] Furthermore, by applying or spraying the dispersion onto a masked substrate layer or support layer, fine patterns can be formed. This is particularly suitable for forming thin films of ITO nanoparticles. This allows for highly accurate dimensional control. For example, when water is used as the solvent for the dispersion, it is preferable to use a water-repellent masking material (water-repellent film) as the masking material. This allows for even more accurate pattern formation.

[0112] (Drying Step) In the step of drying the dispersion liquid supplied onto the substrate layer or the support layer (drying step), specifically, the solvent is vaporized by, for example, irradiation with infrared light or the like, heating, or the like, to form a conductive film on the surface of the substrate. The heating temperature can be set taking into consideration the boiling point of the solvent, the softening point of the substrate, and other effects on the physical properties of the conductive film. The softening point of the substrate here refers to the temperature at which the substrate softens and begins to deform when heated, and can be determined, for example, by a test method in accordance with JIS K7191-1.

[0113] After the drying step, if necessary, a step of slowly cooling the substrate on which the conductive film has been formed (slow cooling step) or a UV irradiation step for the purpose of modifying the base material, such as imparting hydrophilicity, may be carried out.

[0114] In the manufacturing method according to this embodiment, layers containing conductive particles may be formed sequentially on a substrate layer, or layers containing conductive particles may be formed sequentially on a support layer.

[0115] <Conductive Film Manufacturing Method 2> When layers containing conductive particles are sequentially formed on a substrate layer, the following steps are performed: supplying the above-mentioned first solution onto the substrate layer and drying the solvent contained in the first solution to form the first layer; and supplying a second solution onto the first layer and drying the solvent contained in the second solution to form the second layer (see FIG. 1). In this case, the details of the manufacturing method already described can be used for each step unless otherwise specified.

[0116] <Conductive Film Manufacturing Method 3> When a layer containing conductive particles is sequentially formed on a support layer, the following steps are performed: supplying the above-mentioned second solution onto the support layer and drying the solvent contained in the second solution to form the second layer; and supplying the first solution onto the second layer and drying the solvent contained in the first solution to form the first layer (see FIG. 4). In this case, the details of the manufacturing method already described can be used for each step unless otherwise specified.

[0117] The conductive film obtained by the manufacturing method according to this embodiment has a high film density and can reduce the contact resistance with the upper and lower layers.

[0118] 1a, 1b... laminate, 10... substrate layer, 12, 121, 122... conductive layer, 14... support layer, 20, 80... hole transport layer, 30... light-emitting layer, 40, 60... electron transport layer, 50... cathode, 0... anode, 70... active layer, A, C... EL device, B, D... solar cell

Claims

1. A laminate comprising: a substrate layer; a layer comprising first conductive particles on the substrate layer; and a layer comprising second conductive particles on the layer comprising first conductive particles, wherein an average particle diameter of the first conductive particles is larger than an average particle diameter of the second conductive particles.

2. The laminate according to claim 1, wherein the first conductive particles and / or the second conductive particles satisfy the relationship represented by the following formula (1): 16×S / P ２ ≦0.330 (1) (wherein S represents the particle area in the TEM photograph, and P represents the peripheral length of the particle.) 3. The laminate according to claim 1 or 2, wherein the first conductive particles are ITO particles.

4. The laminate according to any one of claims 1 to 3, wherein the second conductive particles are ITO particles.

5. A laminate comprising: a support layer; a layer containing second conductive particles on the support layer; and a layer containing first conductive particles on the layer containing second conductive particles, wherein the average particle diameter of the second conductive particles is smaller than the average particle diameter of the first conductive particles.

6. The laminate according to claim 5, wherein the first conductive particles and / or the second conductive particles satisfy the relationship represented by the following formula (1): 16×S / P ２ ≦0.330 (1) (wherein S represents the particle area in the TEM photograph, and P represents the peripheral length of the particle.) 7. A method for manufacturing a laminate including a first layer and a second layer, comprising: a step of supplying a first solution containing first conductive particles onto a substrate layer or a support layer, and drying the solvent contained in the first solution to form the first layer; and a step of supplying a second solution containing second conductive particles onto the first layer, and drying the solvent contained in the second solution to form the second layer, wherein the first conductive particles and the second conductive particles have different average particle diameters.

8. The method for producing a laminate according to claim 7, wherein the first solution is supplied onto the substrate layer, and the average particle diameter of the first conductive particles is larger than the average particle diameter of the second conductive particles.

9. The method for producing a laminate according to claim 8, wherein a ratio of an average particle size of the first conductive particles to an average particle size of the second conductive particles is 1.3 to 20.

10. The method for producing a laminate according to claim 8 or 9, wherein the first conductive particles or the second conductive particles satisfy the relationship represented by the following formula (1): 16×S / P ２ ≦0.330 (1) (wherein S represents the particle area in the TEM photograph, and P represents the peripheral length of the particle.) 11. The method for producing a laminate according to claim 7, wherein the first solution is supplied onto the support layer, and the average particle diameter of the first conductive particles is smaller than the average particle diameter of the second conductive particles.

12. The method for producing a laminate according to claim 10, wherein a ratio of an average particle size of the second conductive particles to an average particle size of the first conductive particles is 1.3 to 20.

13. The method for producing a laminate according to claim 11 or 12, wherein the first conductive particles or the second conductive particles satisfy the relationship represented by the following formula (1): 16×S / P ２ ≦0.330 (1) (wherein S represents the particle area in the TEM photograph, and P represents the peripheral length of the particle.) 14. The method for producing a laminate according to any one of claims 7 to 13, wherein the first solution is supplied onto the substrate layer in the form of a mist.

15. The method for producing a laminate according to any one of claims 7 to 14, wherein the second solution is supplied onto the substrate layer in the form of a mist.

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