Laminate and method for producing laminate

Abstract

Provided is a laminate (1a) comprising: a substrate layer (10); a layer 121 containing first conductive particles on the substrate layer 10; and a layer 122 containing second conductive particles on the layer 121 containing the first conductive particles, the average particle diameter of the first conductive particles being larger than the average particle diameter of the second conductive particles.

Description

Technical Field

[0001] This invention relates to laminates and methods for manufacturing laminates. Background Technology

[0002] Patent document 1 discloses the following technique for ITO (indium tin oxide) particles as conductive particles: an indium source and a tin source are added to a solution in which a quaternary ammonium ion hydroxide is dissolved in a reducing organic solvent to react, and then the solution is heated in an autoclave and aged under autogenous pressure to obtain ITO particles.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 5706797 Summary of the Invention

[0006] A first aspect of the present invention is 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 the first conductive particles, wherein the average particle size of the first conductive particles is greater than the average particle size of the second conductive particles.

[0007] A second aspect of the present invention is a laminate comprising: a support layer; a layer comprising second conductive particles on the support layer; and a layer comprising first conductive particles on the layer comprising the second conductive particles, wherein the average particle size of the second conductive particles is smaller than the average particle size of the first conductive particles.

[0008] The third aspect of the present invention is a method for manufacturing a laminate comprising a first layer and a second layer. The manufacturing method comprises the following steps: supplying a first solution containing first conductive particles to a substrate layer or a support layer, drying the solvent contained in the first solution to form a first layer; and supplying a second solution containing second conductive particles to the first layer, drying the solvent contained in the second solution to form a second layer, wherein the average particle sizes of the first conductive particles and the second conductive particles are different from each other. Attached Figure Description

[0009] Figure 1 This is a schematic diagram illustrating an example of a laminated body according to this embodiment.

[0010] Figure 2 This is a schematic diagram illustrating an example of an EL device using the stacked structure of this embodiment.

[0011] Figure 3 This is a schematic diagram illustrating an example of a solar cell using the stacked structure of this embodiment.

[0012] Figure 4 This is a schematic diagram illustrating another example of a laminated body according to this embodiment.

[0013] Figure 5 This is a schematic diagram illustrating another example of an EL device using the laminate of this embodiment.

[0014] Figure 6 This is a schematic diagram showing another example of a solar cell using the stacked structure of this embodiment. Detailed Implementation

[0015] The following is a detailed description of a method for implementing the present invention (hereinafter referred to as "this embodiment"). This embodiment is merely an example to illustrate the present invention and is not intended to limit the invention to the following content. It should be noted that in the accompanying drawings, the same symbols are used to denote the same elements, and repeated descriptions are omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the accompanying drawings. Moreover, the scale of the accompanying drawings is not limited to the scale shown in the illustrations.

[0016] <Layered Body 1>

[0017] The first embodiment of the laminate is a laminate comprising: a substrate layer; a first conductive layer comprising first conductive particles on the substrate layer; and a second conductive layer comprising second conductive particles on the first conductive layer, wherein the average particle size of the first conductive particles is larger than the average particle size of the second conductive particles. Such a laminate can suppress contact resistance and interfacial resistance, and is therefore suitable for use as a component in electroluminescent (EL) devices, solar cells, etc.

[0018] Figure 1 This is a schematic diagram illustrating an example of a laminated body according to this embodiment.

[0019] The laminate 1a has a first conductive layer 121 containing first conductive particles and a second conductive layer 122 containing second conductive particles sequentially formed on the substrate layer 10. Furthermore, the average particle size of the first conductive particles is larger than the average particle size of the second conductive particles. That is, the laminate 1a has a conductive layer 12 formed on the substrate layer 10.

[0020] The average particle size mentioned here refers to the particle size obtained by averaging the particle size of primary particles, calculated using the dynamic light scattering method.

[0021] The average particle size of the first conductive particles is preferably 40–100 nm, more preferably 40–70 nm, and even more preferably 40–60 nm.

[0022] The average particle size of the second conductive particles is preferably 5-30 nm, more preferably 5-20 nm, and even more preferably 5-15 nm.

[0023] The ratio of the average particle size of the first conductive particle to the average particle size of the second conductive particle is preferably 1.3 to 20, more preferably 1.3 to 14, and even more preferably 1.3 to 12.

[0024] The thickness of the first conductive layer is preferably 10–1000 nm, more preferably 10–100 nm, and even more preferably 10–20 nm.

[0025] The thickness of the second conductive layer is preferably 10–1000 nm, more preferably 10–100 nm, and even more preferably 10–20 nm.

[0026] Examples of the types of first and second conductive particles (hereinafter sometimes 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 or colorless conductive particles. They may be used individually or in combination of two or more. Preferably, the conductive particles are selected from one or more of the group consisting of ITO particles, ATO particles, PTO particles, and TO particles, and more preferably ITO particles.

[0027] The material of the substrate layer 10 is not particularly limited, and any material suitable for use as a substrate in the aforementioned EL devices, solar cells, etc., can be used. In particular, when the manufacturing method of coating the dispersion onto the substrate layer 10, as described later, is carried out, the limitations on materials are alleviated, and therefore a thin and highly flexible film substrate (sometimes also called a sheet substrate) can be used. Furthermore, continuous production such as roll-to-roll is also possible. From this point of view, materials such as glass, silicon, aluminum, alumina, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), etc., can be used as the substrate layer 10.

[0028] Semiconductors and other components used in EL devices, solar cells, etc., require low resistance. In this regard, in the laminate 1a of this embodiment, by employing a structure in which first conductive particles with a large average particle size are laminated on the substrate layer 10, the number of contact points between the substrate layer and the conductive layer can be reduced, thus lowering the interface resistance at the interface between the substrate layer and the conductive film. Furthermore, within the conductive film, by laminating first conductive particles with a small average particle size on top of the first conductive particles with a large average particle size, the contact area between the particles can be increased, thus reducing the contact resistance between the conductive particles. Therefore, in the laminate 1a, both interface resistance and contact resistance are reduced, resulting in high conductivity.

[0029] The first conductive particle or the second conductive particle, or both of them preferably satisfy the relationship shown in the following formula (1).

[0030]

[0031] (In the formula, S represents the particle area in the TEM photograph, and P represents the outer perimeter length of the particle).

[0032] The particle area S and peripheral length P in Equation (1) are the area and peripheral length of the particle in the TEM photograph, which can be obtained, for example, by the following method.

[0033] First, the TEM images of the conductive particles were processed using the image processing software "imageJ 1.5K". For example, the image of the object was first acquired and converted to 8-bit grayscale. Then, to make the scale of 1 pixel correspond to the actual image, the value of 1 pixel was set to a few nanometers in "Set Scale".

[0034] Next, to clarify the shape of the particles, "Enhance Contrast" is used to set the saturated pixels to 20-40%. This value also affects the overall contrast of the image, so it should be adjusted appropriately, for example, based on how clearly the particle outlines become. Then, binarization is performed using "Threshold" to separate the particle shapes from other parts; an algorithm called "Moments" can be used when setting the threshold.

[0035] Next, select "Analyze Particles" to determine the shape of the particles. In the measurement settings, you can eliminate contamination and background noise by setting "Size (Pixels^2)" to 1000 - Infinity. Pay attention to the "Area" and "Perim." in the results; these can be set to the particle area S and particle perimeter P from the TEM image, respectively.

[0036] The value of the particle area S in this embodiment is not particularly limited; for example, it can be set to 100–4500 nm. 2 It can also be set to 200–4300 nm. 2 In addition, the value of P is not particularly limited; for example, it can be set to 100–1200 nm or 120–1000 nm.

[0037] The upper limit of the value on the left side of equation (1) can 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 using this range, the particle shape can be made into a particle shape that is significantly deformed from a roughly cuboid shape. In addition, the lower limit of the value on the left side of equation (1) is not particularly limited, as long as it is greater than 0, for example, it can be 0.040 or more, 0.060 or more, 0.070 or more, or 0.100 or more.

[0038] The conductive particles of this embodiment can achieve uniform microparticle size and high dispersion, and can also meet the requirements of materials such as low resistance, high transmittance and low turbidity (haze) as materials for various transparent electrodes.

[0039] Previously, conductive particles such as ITO were synthesized through methods such as the gel-sol method, and their particle shape was roughly rectangular. In the gel-sol method, nucleation and growth reactions occur within the gel network. Therefore, ITO particles produced by the gel-sol method have a rectangular shape that reflects their crystalline phase and exhibit high crystallinity.

[0040] In the manufacture of conductive films using conventional conductive particles with a roughly cuboid shape, the theoretical film fill rate is 100% if the conductive particles are arranged with their faces in contact with each other. Therefore, it is considered preferable that the conductive particles have a single-crystal structure close to a cuboid shape. However, the inventors conducted in-depth research and concluded that this is not actually the case; the particles are randomly filled, with the particles in point or line contact with each other. If such an arrangement occurs, the conductive pathways are reduced, and the resistance value increases when used as a transparent conductive film. Furthermore, low dispersibility leads to agglomerated particles, reducing the fill rate or causing a loss of film smoothness. The inventors believe that there is room for improvement in this respect for conventional conductive particles.

[0041] The inventors further investigated the macroscopic state of the conductive particles. As a result, the conductive particles in this embodiment can achieve the effects described above by satisfying the relationship of equation (1). The exact effect is uncertain, but it is believed that the maximum contact area is reduced while maintaining high crystallinity, resulting in good dispersibility in the liquid when a dispersion is prepared (however, the effect of this embodiment is not limited to this).

[0042] Furthermore, there are no particular limitations on the preparation method of conductive particles; well-known methods can be appropriately used. Here, as an example, the case of ITO particles will be explained.

[0043] Regarding the composition of ITO particles, the molar ratio of Sn content to In content (Sn / In) is not particularly limited, but from the viewpoint of crystallization synthesis and conductivity, it is preferably 3.5 to 24, more preferably 3.7 to 23.5, and even more preferably 4 to 23.

[0044] Furthermore, in this embodiment, when using ITO particles that satisfy the above formula (1), it is preferable to manufacture them by the following method instead of the gel-sol method. That is, it is preferable to manufacture them by the following steps: (a) a reaction step, in which ITO particles are obtained by reacting at 190 to 200°C for 12 to 120 hours in a solution containing 0.09 to 0.9 M (M = mol / L) of In salt, 0.01 to 0.2 M (M = mol / L) of Sn salt, an alkaline compound and a solvent; and (b) washing the ITO particles.

[0045] The concentration of In salt in the reaction solution is preferably 0.09–0.9 M, more preferably 0.09–0.45 M. Furthermore, the concentration of Sn salt in the reaction solution is preferably 0.01–0.2 M, more preferably 0.01–0.05 M.

[0046] The concentration of In salt, on a molar basis, is preferably 4.5 to 9 times that of Sn salt, more preferably 5 to 9 times. By carrying out the particle synthesis reaction with this metal source concentration, the ITO particles of this embodiment can be synthesized more easily in a one-pot process.

[0047] There are no particular limitations on the In salt used; any salt known as a raw material for ITO can be used. For example, at least one salt selected from the group consisting of metal salts such as InCl3, In2(C2O4)3, In(NO3)3, In2(SO4)3, and their hydrates can be used. Among these, anhydrous salts or metal salts are preferred, metal salts are more preferred, and InCl3 is even more preferred.

[0048] There are no particular limitations on the Sn salt used; any salt known as a raw material for ITO can be used. For example, at least one salt selected from the group consisting of metal salts such as SnCl2, SnCl4, Sn2(C2O4)3, Sn(NO3)2, SnSO4, and InCl3, and In2(C2O4)3, In(NO3)3, In2(SO4)3, and their hydrates can be used. Anhydrous salts or metal salts are preferred, metal salts are more preferred, and SnCl2 and SnCl4 are even more preferred.

[0049] There are no particular limitations on the type of basic compound; it is acceptable as long as it can neutralize the reaction solution and precipitate (neutralize and co-precipitate) In-Sn hydroxide. Known basic compounds can be used. Examples include tetramethylammonium hydroxide (TMAH) and sodium hydroxide.

[0050] The concentration of the alkaline compound in the reaction solution is not particularly limited, but from the viewpoint of particle synthesis, it is preferably 1 to 2 M, and more preferably 1.5 to 1.7 M.

[0051] As a solvent, any solvent capable of dissolving In salts, Sn salts, basic compounds, and other additives as needed can be used. Known solvents can be used, such as water (preferably); alcohols such as methanol, ethanol, and isopropanol.

[0052] In the reaction step (a), other additives may be added as needed, without hindering the effect of this embodiment.

[0053] (a) The reaction time in the reaction process is preferably 12 hours to 120 hours, more preferably 24 to 72 hours.

[0054] (a) The reaction temperature in the reaction process is preferably 190 to 200°C.

[0055] In step (a), the reaction can be carried out in an open system, but an autoclave is preferred. This promotes the formation of the indium hydroxide-tin hydroxide coprecipitate in the reaction system.

[0056] The mechanism by which ITO particles satisfying the relationship shown in Equation (1) are obtained through the above manufacturing method is still uncertain, but it is believed that the concentration control of the metal salt in the reaction system (M=mol / L), reaction temperature, reaction time, etc. may have an impact. The shape of the monodisperse particles can be controlled by the number of nuclei in the system and the amount of substance present therein, but it is believed that heterogeneous nucleation needs to be further carried out on it while it is kept in a gel network. Therefore, it is believed that it is better to increase the concentration of the metal source so that the amount of base is relatively small relative to the metal source. As a result, the concentration of nucleatable metal oxide precursor can be maintained for a long time. It is believed that synthesis can be carried out by adopting the combination of the above conditions. (However, the effects of this embodiment are not limited to this).

[0057] To produce ITO particles that satisfy the relationship shown in Equation (1), it is preferable to increase the concentration of the metal source while setting the alkali concentration to be relatively low relative to the metal source. Thus, instead of allowing particle growth after the initial nucleation reaction, heterogeneous nucleation can be further carried out on the generated nuclei, resulting in the synthesis of ITO particles that satisfy the relationship shown in Equation (1).

[0058] In this embodiment, it is preferable to perform the centrifugal separation step between (a) the reaction step and (b) the cleaning step. As the centrifugal separation step, it is preferable to perform it at 14,000 rpm for 10 minutes.

[0059] In the step of cleaning ITO particles (b), it is preferable to use water, alcohols such as ethanol, etc. When using water, it is preferable to use distilled water or ion-exchanged water (IEW). Alternatively, it is preferable to use an ultrasonic cleaner to treat the dispersion for cleaning.

[0060] It should be noted that, conventionally, freeze-drying and reduction calcination processes are performed after the reaction process, but these processes can be omitted in this embodiment. From this perspective, it is particularly preferable not to perform the calcination process after process (b). This prevents the aggregation of ITO particles and maintains a monodisperse state in the dispersion medium.

[0061] The laminate 1a can be used as a low-resistance electronic component and can be used to make EL devices and solar cells containing it.

[0062] Figure 2 This is a schematic diagram illustrating an example of an EL device using the stacked structure of this embodiment.

[0063] The EL device A has a hole transport layer 20, a light-emitting layer 30, an electron transport layer 40, and a cathode 50 sequentially formed on the second conductive layer 122 of the laminate 1a. The conductive layer 122 also functions as the anode. The anode (conductive layer 12) and the cathode 50 are connected to a driving power supply.

[0064] When an EL device A is subjected to a voltage supplied from a driving power source, holes and electrons are transported to the hole transport layer 20 and electron transport layer 40, respectively, and they combine in the light-emitting layer 30 to emit light. The light from the light-emitting layer 30 is extracted from the transparent substrate layer 10 for external display.

[0065] The substrate layer 10 is a light-transmitting substrate, such as a glass substrate, PET substrate, PEN substrate, or other film substrate.

[0066] The conductive layer 12 functions as a transparent electrode, for example, an ITO electrode or a graphene electrode can be used.

[0067] Hole transport layer 20 can use, for example, PEDOT:PSS, etc.

[0068] The luminescent layer 30 can be, for example, Alq3 (tris-(8-hydroxyquinoline)aluminum), etc.

[0069] Electron transport layer 40 may, for example, use 2-[4-(9,10-di-naphthyl-2-yl-anthracite-2-yl)phenyl]-1-phenyl-1H-benzimidazole, etc.

[0070] The cathode 50 can be made of metals such as Cu.

[0071] In addition, although not shown in the figure, in order to reduce the work function difference with the hole transport layer 20, an adjustment layer can be provided between the hole transport layer 20 and the conductive layer 12 as needed.

[0072] Figure 3 This is a schematic diagram illustrating an example of a solar cell using the stacked structure of this embodiment.

[0073] In solar cell B, an electron transport layer 60, an active layer 70, a hole transport layer 80, and an anode 90 are sequentially formed on the second conductive layer 122 of the laminate 1a. Furthermore, the conductive layer 122 functions as a cathode.

[0074] Solar cell B receives light on the transparent substrate layer 10 side, and is excited by light irradiating the active layer 70. The generated electrons and holes 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. Furthermore, current can be extracted from an external circuit (not shown) connected to the cathode (conductive layer 12) and the anode 90.

[0075] The substrate layer 10 is a light-transmitting substrate, such as a glass substrate, PET substrate, PEN substrate, or other film substrate.

[0076] The conductive layer 12 functions as a transparent electrode, and can be made of materials such as ITO, ATO (antimony-doped tin oxide), FTO (fluorine-doped tin oxide), or AZO (aluminum-doped zinc oxide).

[0077] Electron transport layer 60 can be made of materials such as LiF2 or TiO2.

[0078] Active layer 70 can, for example, use C 60 CuPc (copper phthalocyanine), etc.

[0079] For example, Al, Cu, etc. can be used as the cathode 50.

[0080] Hole transport layer 80 can use, for example, PEDOT:PSS, V2O5, MoO3, etc.

[0081] <Layered Body 2>

[0082] The second embodiment of the laminate is 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 the second conductive particles, wherein the average particle size of the second conductive particles is smaller than the average particle size of the first conductive particles. Such a laminate can suppress contact resistance and interfacial resistance, and is therefore suitable for use as a component in EL devices, solar cells, etc.

[0083] Figure 4 This is a schematic diagram illustrating another example of a laminated body according to this embodiment.

[0084] The laminate 1b has a second conductive layer 122 containing second conductive particles and a first conductive layer 121 containing first conductive particles sequentially formed on the support layer 14. Furthermore, the average particle size of the first conductive particles is larger than the average particle size of the second conductive particles (the average particle size of the second conductive particles is smaller than the average particle size of the first conductive particles). Hereinafter, unless otherwise specified, the same components as those in the laminate 1b may be appropriately used.

[0085] The first conductive particle or the second conductive particle, or preferably both of them, satisfy the relationship shown in equation (1) above.

[0086] The material of the support layer 14 is not particularly limited, and any material suitable for use as a support layer in the aforementioned EL devices, solar cells, etc., can be used. Examples of materials that can be used as support layers include PEDOT:PSS, etc.

[0087] The average particle size of the first conductive particles is preferably 40–100 nm, more preferably 40–70 nm, and even more preferably 40–60 nm.

[0088] The average particle size of the second conductive particles is preferably 5-30 nm, more preferably 5-20 nm, and even more preferably 5-15 nm.

[0089] The ratio of the average particle size of the first conductive particle to the average particle size of the second conductive particle is preferably 1.3 to 20, more preferably 1.3 to 14, and even more preferably 1.3 to 12.

[0090] The thickness of the first conductive layer is preferably 10–1000 nm, more preferably 10–100 nm, and even more preferably 10–20 nm.

[0091] The thickness of the second conductive layer is preferably 10–1000 nm, more preferably 10–100 nm, and even more preferably 10–20 nm.

[0092] In the laminate 1b of this embodiment, a structure is adopted in which second conductive particles with a small average particle size are laminated on a support layer 14 with a finely textured 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, by laminating first conductive particles with a large average particle size on the second conductive particles with a small average particle size, the contact area between the particles is increased, thereby reducing the contact resistance between the conductive particles. Thus, in the laminate 1b, both interfacial resistance and contact resistance are reduced, resulting in high conductivity.

[0093] Figure 5 This is a schematic diagram illustrating another example of an EL device using the laminate of this embodiment.

[0094] The EL device C has a substrate layer 10 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 sequentially formed on the support layer 14. The conductive layer 122 functions as the anode, and the support layer 14 functions as the hole transport layer. The anode (conductive layer 12) and the cathode 50 are connected to a driving power supply. Unless otherwise specified, the same components as those in the EL device A described above can be used for the EL device C.

[0095] When an EL device C is powered by a voltage supplied from a driving power source, holes and electrons are transported to the hole transport layer (support layer 14) and electron transport layer 40, respectively, and they combine in the light-emitting layer 30 to emit light. The light from the light-emitting layer 30 is extracted from the transparent substrate layer 10 for external display.

[0096] The support layer 14 only needs to function as a hole transport layer, and the material of the hole transport layer described above can be used.

[0097] The substrate layer 10 is the same as the substrate layer described above, and can be a light-transmitting substrate layer.

[0098] Figure 6 This is a schematic diagram showing another example of a solar cell using the stacked structure of this embodiment.

[0099] Solar cell D has a substrate layer 10 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 sequentially formed on the support layer 14. The conductive layer 122 functions as a cathode, and the support layer 14 functions as an electron transport layer. Unless otherwise specified, the same components as those used in solar cell B can be used for solar cell D.

[0100] Solar cell D receives light on the transparent substrate layer 10 side, and is excited by light irradiating the active layer 70. The generated electrons and holes are transported by the electron transport layer (support layer 14) and hole transport layer 80, respectively, and extracted by the cathode (conductive layer 12) and anode 90. Furthermore, current can be extracted from an external circuit (not shown) connected to the cathode (conductive layer 12) and anode 90.

[0101] The support layer 14 only needs to function as an electron transport layer, and the aforementioned electron transport layer material can be used.

[0102] The substrate layer 10 is the same as the substrate layer described above, and can be a light-transmitting substrate layer.

[0103] <Methods for manufacturing conductive films>

[0104] According to this embodiment, the above-described laminate can be used to manufacture a conductive film.

[0105] A preferred example of a method for manufacturing a conductive film comprising the first conductive layer and the second conductive layer described above includes the following steps: (1) A first solution containing first conductive particles is supplied to a substrate layer or a support layer, and the solvent contained in the first solution is dried, thereby forming a first conductive layer; and (2) A second solution containing the second conductive particles is supplied onto the first layer, causing the solvent contained in the second solution to dry, thereby forming the second conductive layer. The average particle sizes of the first conductive particle and the second conductive particle are different.

[0106] 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.

[0107] The substrate layer and the support layer can be any substrate layer and support layer that can be used in the above-described laminate.

[0108] A layer containing conductive particles can be formed by supplying a dispersion in which the conductive particles are dispersed in a solvent and then drying the solvent.

[0109] (Supply process)

[0110] As a process of supplying a dispersion to a substrate layer and a support layer (supply process), a method of dispersing conductive particles in a solvent by coating or spraying can be used.

[0111] The solvent for the dispersion is not particularly limited, and examples include water, methanol, ethanol, isopropanol, and other alcohols, as well as mixtures thereof. Among these, water and alcohols are preferred, and water is more preferred. That is, the dispersion of this embodiment is suitable for use as an aqueous dispersion.

[0112] The dispersion can be mixed with other additives as needed.

[0113] In particular, when ordinary conductive particles are dispersed in a solvent for a long time, a surfactant is needed to prevent particle aggregation. However, the dispersion used in this embodiment can be made into a dispersion in which conductive particles can be dispersed for a long time even without the addition of a surfactant. Therefore, the dispersion of this embodiment can be made into a dispersion that is substantially free of surfactant, that is, a surfactant-free dispersion.

[0114] The surfactants mentioned here refer to surfactants that have the function of adsorbing onto the surface of particles and dispersing particles in a dispersion medium. Specific examples include anionic surfactants, cationic surfactants, and nonionic surfactants.

[0115] In the dispersion, the ratio (volume ratio) of conductive particles to solvent is not particularly limited, but is preferably 40% or less. By setting it within this range, long-term stable monodispersion is possible.

[0116] There are no particular limitations on the dispersion method; methods such as stirring with a stirrer or ultrasonic dispersion with an ultrasonic bath can be used, or a combination of these methods can be used. Among these, an ultrasonic bath is preferred.

[0117] The dispersion can be directly coated onto the substrate layer, or it can be atomized and sprayed onto the substrate layer. Furthermore, it can be applied under atmospheric pressure, reduced pressure, or vacuum; from a simplicity perspective, atmospheric pressure is preferred.

[0118] For example, in the manufacture of ITO films as conductive films, ITO is a raw material with high conductivity and transparency, and is widely used as a transparent conductive material. One method for manufacturing ITO films includes sputtering and laser evaporation; however, these techniques struggle to form uniform films on flexible substrates, failing to fully utilize the excellent surface properties of ITO. Furthermore, the evaporation process requires large-scale equipment structures, and there is room for improvement in this regard.

[0119] Regarding this, the components of the dispersion in this embodiment do not settle and have high dispersibility, thus allowing for the use of simple coating or fogging techniques when forming an ITO thin film on a substrate. Furthermore, limitations related to the substrate material are mitigated, enabling film formation even on flexible substrates as described above. Moreover, according to this embodiment, even when fabricating nanoscale ITO particles (ITO nanoparticles), high crystallinity and monodispersity can be stably maintained, thus allowing for high-level control of surface properties such as conductivity and transparency of the thin film.

[0120] There are no particular limitations on the atomization method; any method that produces a mist from the dispersion is acceptable. Known methods can be used to generate the mist, such as pressurized, rotating disc, ultrasonic, electrostatic, throttling vibration, and steam atomization. In this embodiment, since it is a dispersion of ITO particles, physical atomization is preferred. This makes temperature control and droplet size control easier. Furthermore, by treating the dispersion as a mist, high controllability is achieved, avoiding the deformation issues that occur during film formation in sol-gel methods where liquid supply is performed.

[0121] In atomization, a carrier gas can be used to transport the mist of the dispersion to the subsequent contact process. Inert gases such as argon, helium, and nitrogen can be used as carrier gases.

[0122] In atomization, further processes can be performed, such as using a fog eliminator to homogenize the fog and setting the fog's residence period (retention section).

[0123] In addition, regarding spraying methods, examples include ultrasonic spraying, atomized CVD, Sonaer source spraying, and hot-wall spraying. These methods can be selected by considering factors such as the thickness of the conductive film formed on the substrate layer and the size of the sprayed droplets.

[0124] Furthermore, by coating or spraying the dispersion onto the masked substrate or support layer, fine patterns can be formed. This is particularly suitable for cases where ITO nanoparticles are formed into thin films. This allows for high-precision dimensional control. For example, if water is used as the solvent for the dispersion, a waterproof masking material (waterproof membrane) is preferably used. This allows for even higher precision in pattern formation.

[0125] (Drying process)

[0126] The process of drying the dispersion supplied to the substrate layer or support layer (drying process) specifically involves vaporizing the solvent by means of light irradiation such as infrared radiation or heating, thereby forming a conductive film on the surface of the substrate. The heating temperature can be set taking into account 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, as referred to here, is the temperature at which the substrate softens and begins to deform when heated, and can be determined, for example, by a test method based on JIS K7191-1.

[0127] After the drying process, a process can be performed as needed, such as a slow cooling process (slow cooling process) to slowly cool the substrate on which the conductive film has been formed, or a UV irradiation process for the purpose of modifying the substrate to impart hydrophilicity.

[0128] The manufacturing method of this embodiment can sequentially form a layer containing conductive particles on a substrate layer, or sequentially form a layer containing conductive particles on a support layer.

[0129] <Method 2 for Manufacturing Conductive Films>

[0130] When a layer containing conductive particles is sequentially formed on a substrate layer, the following steps are performed: supplying the first solution to the substrate layer, drying the solvent contained in the first solution, thereby forming a first layer; and supplying a second solution to the first layer, drying the solvent contained in the second solution, thereby forming a second layer (see reference). Figure 1 At this point, unless otherwise specified, the manufacturing method already described can be used for each process.

[0131] <Method 3 for Manufacturing Conductive Films>

[0132] When a layer containing conductive particles is sequentially formed on a support layer, the following steps are performed: supplying the second solution to the support layer to dry the solvent contained in the second solution, thereby forming a second layer; and supplying the first solution to the second layer to dry the solvent contained in the first solution, thereby forming a first layer (see reference). Figure 4 At this point, unless otherwise specified, the manufacturing method already described can be used for each process.

[0133] The conductive film obtained by the manufacturing method of this embodiment has a high film density, which can reduce the contact resistance with the upper and lower layers.

[0134] Symbol Explanation

[0135] 1a, 1b…Laminated structure, 10…Substrate layer, 12, 121, 122…Conductive layers, 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: Substrate layer; A layer containing first conductive particles, situated on the substrate layer; and A layer containing second conductive particles, situated on top of the layer containing first conductive particles. The average particle size of the first conductive particle is greater than the average particle size of the second conductive particle.

2. The laminated body according to claim 1, wherein, The first conductive particle and / or the second conductive particle satisfy the relationship shown in equation (1) below. In the formula, S represents the particle area in the TEM photograph, and P represents the outer perimeter length of the particle.

3. The laminate according to claim 1 or 2, wherein, The first conductive particle is an ITO particle.

4. The laminate according to any one of claims 1 to 3, wherein, The second conductive particle is an ITO particle.

5. A laminate comprising: Support layer; A layer containing second conductive particles, situated on the support layer; and A layer containing first conductive particles, situated on the layer containing second conductive particles, The average particle size of the second conductive particle is smaller than the average particle size of the first conductive particle.

6. The laminate according to claim 5, wherein, The first conductive particle and / or the second conductive particle satisfy the relationship shown in equation (1) below. In the formula, S represents the particle area in the TEM photograph, and P represents the outer perimeter length of the particle.

7. A method for manufacturing a laminated body, comprising a first layer and a second layer, wherein, The manufacturing method comprises the following steps: A first solution containing first conductive particles is supplied to a substrate layer or a support layer, and the solvent contained in the first solution is dried, thereby forming the first layer; and A second solution containing the second conductive particles is supplied onto the first layer, causing the solvent in the second solution to dry, thereby forming the second layer. The average particle size of the first conductive particle and the second conductive particle are different from each other.

8. The method for manufacturing a laminate according to claim 7, wherein, The first solution is supplied to the substrate layer, and The average particle size of the first conductive particle is greater than the average particle size of the second conductive particle.

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

10. The method for manufacturing a laminate according to claim 8 or 9, wherein, The first conductive particle or the second conductive particle satisfies the relationship shown in the following equation (1). In the formula, S represents the particle area in the TEM photograph, and P represents the outer perimeter length of the particle.

11. The method for manufacturing a laminate according to claim 7, wherein, The first solution is supplied to the support layer, and The average particle size of the first conductive particle is smaller than the average particle size of the second conductive particle.

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

13. The method for manufacturing a laminate according to claim 11 or 12, wherein, The first conductive particle or the second conductive particle satisfies the relationship shown in the following equation (1). In the formula, S represents the particle area in the TEM photograph, and P represents the outer perimeter length of the particle.

14. The method for manufacturing a laminate according to any one of claims 7 to 13, wherein, The first solution is atomized and supplied to the substrate layer.

15. The method for manufacturing a laminate according to any one of claims 7 to 14, wherein, The second solution is atomized and supplied to the substrate layer.

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