JP2010129831A - Organic photoelectric conversion element, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoelectric conversion element which has high photoelectric conversion efficiency and flexibility, and to provide a method of manufacturing the same. <P>SOLUTION: The method of manufacturing the organic photoelectric conversion element having, on a transparent base, a first electrode having a transparent conductive layer formed containing at least conductive fiber and conductive metal oxide, a photoelectric conversion layer portion constituted containing a p-type semiconductor material and an n-type semiconductor material, and a second electrode, includes a coating process of coating the transparent base with a solution containing at least one kind of conductive fiber and a solution containing at least one kind of conductive metal oxide having electromagnetic wave absorbing capability, a process of forming the photoelectric conversion layer portion on the first electrode by coating, and a process of irradiating the member having the photoelectric conversion layer portion formed by the coating with an electromagnetic wave. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic photoelectric conversion element excellent in power generation efficiency and flexibility and a method for producing the same.

  Gretzell et al. Dye-sensitized photoelectric conversion that has performance close to that of amorphous silicon photoelectric conversion elements by forming a film of organic dye with photoelectric conversion function on a transparent electrode such as titanium oxide and filling the space with an electrolyte. The element is reported (for example, nonpatent literature 1).

  However, since this dye-sensitized photoelectric conversion element is a wet solar cell in which electrical connection with the counter electrode is performed by a liquid redox electrolyte, the photoelectric conversion function is remarkably deteriorated due to depletion or leakage of the electrolyte when used over a long period of time. Therefore, there is a concern that it will not function as a photoelectric conversion element.

  Therefore, an electron donor layer (p-type semiconductor layer) and an electron acceptor layer (n) are formed between the transparent electrode and the counter electrode as a photoelectric conversion element that can be formed by a cost-effective solution coating method without using an electrolytic solution. Heterojunction type (laminated type) photoelectric conversion element (for example, Patent Document 1) with a p-type semiconductor polymer and an n-type semiconductor material uniformly between a transparent electrode and a counter electrode A bulk heterojunction organic photoelectric conversion element including a mixed bulk hetero layer has been proposed.

  The operation principle of the organic photoelectric conversion element will be described. First, the dye / conductive polymer generates excitons by light absorption, and the generated excitons move to the contact interface between the p-type semiconductor and the n-type semiconductor, where charge is generated. Separation occurs. Electrons generated by charge separation pass through the n-type semiconductor layer, and holes pass through the p-type semiconductor layer and are carried to one electrode. As a result, a photocurrent is observed.

  Organic thin-film solar cells composed of organic photoelectric conversion elements can be formed by a coating method, and thus have attracted attention as solar cells suitable for mass production and are actively studied by many research institutions. The organic thin-film solar cell improves the charge separation efficiency, which has been a problem, by a so-called bulk heterojunction structure in which an electron donor material and an electron acceptor material are mixed (for example, Patent Document 2). In recent years, the photoelectric conversion efficiency has improved to the 5-6% range, and it can be said that this is a field where research for practical use has become more active. However, in organic photoelectric conversion elements for practical use in the future, development of organic photoelectric conversion elements that generate power with higher efficiency is desired.

  In the bulk heterojunction structure, it is considered that the p-type semiconductor and the n-type semiconductor have a micro phase separation structure in which a sea-island structure is taken microscopically. For example, after coating a transparent substrate with a blend solution of P3HT, which is a conductive polymer as a p-type semiconductor, and PCBM, which is a fullerene derivative, as an n-type semiconductor, the temperature is about 140 to 200 ° C. for 10 minutes to 60 minutes. When annealing is performed for about a minute, crystallization of the conductive polymer P3HT is promoted simultaneously with microphase separation. As a result, the contact interface between P3HT and PCBM increases, thereby promoting photo-charge separation and forming a conduction path as a transport path for carriers (electrons and holes), resulting in a state in which recombination is further suppressed, It is thought that conversion efficiency improves.

  Regarding the heat treatment of organic semiconductors used in the power generation layer, many proposals have been made so far, such as proposals concerning the temperature during heat treatment and proposals for exposure to solvent vapor during heat treatment using a hot plate or oven. (For example, patent document 3). In recent years, by applying a power generation layer on an ITO glass substrate and performing an annealing treatment by microwave irradiation, crystallization of the conductive polymer in the bulk heterojunction layer is promoted more than the annealing treatment by heating. Has been reported (for example, Non-Patent Document 2). However, none of them is fully satisfactory from the viewpoints of conversion efficiency, productivity, and bending resistance in the case of a flexible type.

  On the other hand, as a transparent electrode excellent in productivity, a method of forming a transparent electrode by coating or printing using a coating liquid obtained by dissolving or dispersing a conductive polymer material typified by a π-conjugated polymer in an appropriate solvent Has also been proposed (see, for example, Patent Document 4). However, compared with a metal oxide transparent electrode such as ITO formed by a vacuum film formation method, there is a problem that the conductivity is low and the transparency is inferior.

Furthermore, a technique using conductive fibers such as carbon nanotubes (CNT) and metal nanowires is also disclosed. A part of the conductive fibers is fixed to the substrate with a transparent resin film, and a part of the conductive fibers is transparent. It has been proposed to form electrodes by projecting on the surface of the resin film (see, for example, Patent Document 5). However, since the electrode having such a structure has conductivity only in the portion where the conductive fiber protrudes on the surface, it does not have a function as a surface electrode, and in addition, the conductive fiber protrudes on the surface. Therefore, it has a problem that it cannot be applied to the use of an organic photoelectric conversion element that requires smoothness of the electrode surface.
Japanese Patent No. 40671115 US Pat. No. 5,331,183 US Pat. No. 7,306,968 JP-A-6-273964 JP 2006-519712 A Journal of the America Chemical Society 115 (1993) 6382 Adv. Mater, 2007, 19, 3520-3523

  An object of the present invention is to provide an organic photoelectric conversion element having high photoelectric conversion efficiency and suitability when flexible, and a method for producing the same.

  The above object of the present invention can be achieved by the following configuration.

  1. A first electrode having a transparent conductive layer comprising at least a conductive fiber and a conductive metal oxide on a transparent substrate; a photoelectric conversion layer portion comprising a p-type semiconductor material and an n-type semiconductor material; In the method for producing an organic photoelectric conversion element having two electrodes, a solution containing at least one type of conductive fiber and a solution containing at least one type of conductive metal oxide having electromagnetic wave absorbing ability are coated on a transparent substrate. By a process having at least a step of coating the first electrode composition, a step of coating the photoelectric conversion layer portion on the first electrode, and a step of irradiating the member on which the photoelectric conversion layer portion is coated with electromagnetic waves A method for producing an organic photoelectric conversion element produced by the method.

  2. 2. The method for producing an organic photoelectric conversion element as described in 1 above, wherein the electromagnetic wave is a microwave.

  3. 3. The method for producing an organic photoelectric conversion element according to 1 or 2, wherein the conductive fiber is at least one selected from the group consisting of metal nanowires and carbon nanotubes.

  4). 4. The method for producing an organic photoelectric conversion element according to any one of 1 to 3, wherein the conductive metal oxide is tin oxide and / or tin oxide sol.

  5. 5. An organic photoelectric conversion element produced by the method for producing an organic photoelectric conversion element according to any one of 1 to 4 above.

  According to the present invention, not only an organic photoelectric conversion element having high photoelectric conversion efficiency but also an organic photoelectric conversion element excellent in flexibility can be provided when a flexible substrate is used. Moreover, the manufacturing method is provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of earnest studies on the improvement of the efficiency of the organic photoelectric conversion element and the problem of imparting flexibility when it is made into a flexible type, the present inventor has at least conductive fibers and conductive metal oxides on the transparent substrate. In the manufacturing method of the organic photoelectric conversion element which has the 1st electrode which has the transparent conductive layer comprised, the photoelectric conversion layer part comprised including the p-type semiconductor material and the n-type semiconductor material, and the second electrode, respectively, A first electrode composition coating step of coating a solution containing at least one type of conductive fiber and a solution containing at least one type of conductive metal oxide having electromagnetic wave absorption capability; An organic photoelectric conversion element having a high photoelectric conversion efficiency is created by forming an organic photoelectric conversion element by a step of coating the conversion layer portion and a step of irradiating the member on which the photoelectric conversion layer portion is coated with electromagnetic waves. And, an organic photoelectric conversion element having flexibility found that can be achieved is completed the invention.

  Hereinafter, these will be described in detail.

(Transparent substrate)
The transparent substrate used for the transparent electrode of the present invention is not particularly limited as long as it has high light transmittance. For example, a glass substrate, a resin substrate, a resin film, and the like are preferable in terms of excellent hardness as a base material and ease of formation of a conductive layer on the surface. From the viewpoint, it is preferable to use a transparent resin film.

  There is no restriction | limiting in particular in the transparent resin film which can be preferably used as a transparent base material in this invention, About the material, a shape, a structure, thickness, etc., it can select suitably from well-known things. For example, polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate, modified polyester, polyethylene (PE) resin films, polypropylene (PP) resin films, polystyrene resin films, polyolefin resin films such as cyclic olefin resins, Vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF) resin film, polyether sulfone (PES) resin film, polycarbonate (PC) resin film, polyamide resin A film, a polyimide resin film, an acrylic resin film, a triacetyl cellulose (TAC) resin film, and the like can be given. If the resin film transmittance of 80% or more in nm), can be preferably applied to a transparent resin film according to the present invention. Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. More preferred are polyethylene terephthalate films and biaxially stretched polyethylene naphthalate films.

  The transparent substrate used in the present invention can be subjected to a surface treatment or an easy-adhesion layer in order to ensure the wettability and adhesion of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment. Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion. In addition, a barrier coat layer may be formed in advance on the transparent substrate, or a hard coat layer may be formed in advance on the side opposite to the provision of the translucent first electrode.

[First electrode]
In the organic photoelectric conversion element of the present invention, the first electrode having a transparent conductive layer is not particularly limited to a cathode and an anode, and can be selected according to the element configuration, but preferably the transparent electrode is used as an anode. .

  FIG. 1 shows a structural schematic diagram of the first electrode having the transparent conductive layer of the present invention. The first electrode 4 of the present invention includes at least the metal nanowire 1 on the transparent base material 5 and, as a preferable configuration, the first transparent resin 3 that is held and bound to the entire side close to the transparent base material. And having a second transparent resin component-containing part or a transparent inorganic component-containing part 2 containing the conductive metal oxide 12 on the side far from the transparent substrate.

  In the example of FIG. 1, the transparent resin component-containing portion 2 including the conductive metal oxide 6 exists in the gap on the electrode surface side of the three-dimensional mesh structure (conductive network structure) formed by the metal nanowires 1. The metal nanowire 1 can function as an auxiliary electrode of the transparent inorganic component-containing part 2 at the same time as constituting the surface of the electrode together with the transparent resin component-containing part 2. In addition, the first transparent resin 3 exists between the gap on the transparent base material 5 side of the three-dimensional mesh structure of the metal nanowire 1 and the transparent base material 5, and the metal nanowire 1 -containing portion becomes the transparent base material 5. It is fixed.

  In the first electrode 4 of the present invention, the total light transmittance is preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more. The total light transmittance can be measured according to a known method using a spectrophotometer or the like. In addition, the electrical resistance value of the first electrode portion of the present invention is preferably 50Ω / □ or less, more preferably 10Ω / □ or less, and particularly preferably 3Ω / □ or less as the surface resistivity. preferable. If it exceeds 50Ω / □, the photoelectric conversion efficiency may be inferior in an organic photoelectric conversion element having a large light receiving area. The surface resistivity can be measured in accordance with, for example, JIS K 7194: 1994 (resistivity test method using a conductive plastic four-probe method), and can be easily performed using a commercially available surface resistivity meter. Can be measured.

  There is no restriction | limiting in particular in the thickness of the transparent electrode of this invention, Although it can select suitably according to the objective, Generally it is preferable that it is 10 micrometers or less, and transparency and a softness | flexibility improve, so that thickness becomes thin. More preferred.

[Metal nanowires]
As the conductive fiber of the present invention, an organic fiber or inorganic fiber coated with a metal, a conductive metal oxide fiber, a metal nanowire, a carbon fiber, a carbon nanotube, or the like can be used, and a metal nanowire is preferable.

  In general, a metal nanowire refers to a linear structure having a metal element as a main component. In particular, the metal nanowire in the present invention means a linear structure having a diameter of nm size.

  The metal nanowire according to the present invention preferably has an average length of 3 μm or more in order to form a long conductive path with a single metal nanowire and to exhibit appropriate light scattering properties. 3-500 micrometers is preferable and it is especially preferable that it is 3-300 micrometers. In addition, the relative standard deviation of the length is preferably 40% or less. Moreover, it is preferable that an average diameter is small from a transparency viewpoint, On the other hand, the larger one is preferable from an electroconductive viewpoint. In this invention, 10-300 nm is preferable as an average diameter of metal nanowire, and it is more preferable that it is 30-200 nm. In addition, the relative standard deviation of the diameter is preferably 20% or less.

  There is no restriction | limiting in particular as a metal composition of the metal nanowire which concerns on this invention, Although it can be comprised from the 1 type or several metal of a noble metal element or a base metal element, it is a noble metal (For example, gold, platinum, silver, palladium, rhodium, iridium) , Ruthenium, osmium, etc.) and at least one metal belonging to the group consisting of iron, cobalt, copper, and tin, and more preferably at least silver from the viewpoint of conductivity. In order to achieve both conductivity and stability (sulfurization and oxidation resistance of metal nanowires and migration resistance), it is also preferable to include silver and at least one metal belonging to a noble metal other than silver. When the metal nanowire according to the present invention includes two or more kinds of metal elements, for example, the metal composition may be different between the inside and the surface of the metal nanowire, or the entire metal nanowire has the same metal composition. May be.

  In the present invention, the means for producing the metal nanowire is not particularly limited, and for example, known means such as a liquid phase method and a gas phase method can be used. Moreover, there is no restriction | limiting in particular in a specific manufacturing method, A well-known manufacturing method can be used. For example, as a method for producing Ag nanowires, Adv. Mater. , 2002, 14, 833-837; Chem. Mater. , 2002, 14, 4736-4745, etc. As a method for producing Co nanowires, a method for producing Au nanowires is disclosed in JP 2006-233252A, and a method for producing Cu nanowires is disclosed in JP 2002-266007 A, etc. Reference can be made to Japanese Unexamined Patent Publication No. 2004-149871. In particular, Adv. Mater. And Chem. Mater. The method for producing Ag nanowires reported in (1) can be easily produced in an aqueous system, and since the conductivity of silver is the highest among metals, it is preferable as the method for producing metal nanowires according to the present invention. Can be applied.

  In the present invention, metal nanowires contact each other to form a three-dimensional conductive network, exhibiting high conductivity, and allowing light to pass through the conductive network window where no metal nanowire exists. In addition, the power generation from the organic power generation layer can be efficiently performed by the scattering effect of the metal nanowires. If the metal nanowire is installed on the side closer to the organic power generation layer in the first electrode, this scattering effect can be used more effectively, which is a more preferable embodiment.

(Configuration other than the metal nanowire of the first electrode)
In the present invention, by including the metal nanowire in the first electrode, in addition to the effect of scattering the light of the metal nanowire, the metal nanowire has high conductivity. It is possible to use a relatively low refractive index resin or the like together, which makes it possible to keep the refractive index of the first electrode lower than the photoelectric conversion layer portion (power generation layer portion). Reflection at each interface between the one electrode and the power generation layer portion can be suppressed, and light can effectively reach the power generation layer portion. In order to effectively express this effect, it is preferable that the average refractive index of the first electrode is lower than the average refractive index of the photoelectric conversion layer (power generation layer) portion.

  Although the first electrode of the present invention contains metal nanowires, it is preferably used in combination with some transparent resin or transparent inorganic material in order to hold the metal nanowires, and the material is appropriately selected so as to satisfy the above-described refractive index relationship. Just choose. Such materials are not particularly limited, but for example, polyester resins, polystyrene resins, acrylic resins, polyurethane resins, acrylic urethane resins, polycarbonate resins, cellulose resins, butyral resins, etc. may be used alone or in combination. Can be used. Further, a UV curable resin may be used.

  Furthermore, as a preferred embodiment, when the first electrode is divided by half the film thickness, the average haze value of the portion on the side different from the photoelectric conversion layer (power generation layer) portion is EH1, and the portion on the side close to the transparent substrate When the average haze value is EH2, it is preferable that EH1 <EH2. By doing so, the optical path length can be extended more effectively by scattering of the incident light, and the scattering effect of the metal nanowire of the present invention can be maximized.

  The haze value of the first electrode can be changed depending on the content and diameter of the metal nanowire, the content and particle diameter of a conductive metal oxide described later, and the like.

  The first electrode contains at least a first transparent resin component (for example, the aforementioned resin) and a second transparent resin component having a higher refractive index than the transparent resin component in addition to the metal nanowire, and the second transparent resin component and the metal The nanowire is configured so that the first transparent resin component is included in a large amount on the side close to the organic power generation layer part, and the first electrode part is added to the metal nanowire at least in the first side. A transparent resin component and a transparent inorganic component having a refractive index higher than that of the transparent resin component, wherein the transparent resin component and the metal nanowire are closer to the photoelectric conversion layer (power generation layer), It is also a preferred embodiment of the present invention that a large amount is included on each side close to the transparent substrate.

  As the above-mentioned second transparent resin component, a conductive polymer is preferable, and in order to exhibit the effects of the present invention, a conductive metal oxide that absorbs microwaves is used as the above-mentioned transparent inorganic component.

  By using the microwave-absorbing conductive metal oxide together with the metal nanowire or the second transparent resin component, necking is promoted in the conductive network of the metal nanowire in the first electrode due to heat generated by microwave irradiation / absorption. It is estimated that this improves the electrical conductivity and transparency of the electrode, functions as a complete surface electrode, and improves the electrode performance.

  As a result, the power generation performance is improved, and the flexibility is improved such that the bending resistance and the efficiency retention after bending are improved.

  At the same time, the heat generated in the first electrode due to electromagnetic wave irradiation is transmitted to the below-described photoelectric conversion layer portion by this heat generation, thereby promoting the microphase separation or crystallization of the semiconductor in the photoelectric conversion layer, It is considered that the effect of suppressing photoelectric recombination by improving the photoelectric charge separation and forming the conduction path of carriers (electrons, holes) and improving the photoelectric conversion efficiency.

Examples of the conductive metal oxide include ZrO ₂ , CeO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₂ , V ₂ O _5, etc. Examples thereof include metal oxide fine particles, composite oxide fine particles thereof, composite metal oxide fine particles doped with different atoms, or metal oxide sols thereof, and microwave absorption characteristics and conductivity that are essential in the present invention. Indium oxide (ITO, IZO) doped with tin or zinc, zinc oxide doped with aluminum or gallium (AZO, GZO), tin oxide doped with fluorine or antimony (FTO, ATO), etc. Fine particles and sols can be preferably used. These may be used alone or in combination with other resin components.

  In addition, metal oxide fine particles, composite metal oxide fine particles, metal oxide sol, or the like, which are precursors of these conductive metal oxides, can be used in combination.

  Further, when fine particles are contained in the first transparent resin component of the present invention, it becomes possible to improve the light uptake at the interface between the first electrode portion and the transparent substrate, which is a more preferred embodiment of the present invention. . The particle diameter is preferably 0.05 to 5 μm, more preferably 0.05 to 2 μm. If it is less than 0.05 μm, the effect of scattering and refracting light is small, and if it is larger than 5 μm, smoothness becomes a problem. The refractive index of the particles is preferably from 1.1 to 2.0, and more preferably from 1.3 to 1.7. Within this range, there are few components that scatter light back, and light capture efficiency can be improved while suppressing a decrease in transmittance. As such fine particles, cross-linked acrylic particles, cross-linked styrene-based fine particles, silica-based fine particles, melamine / formaldehyde condensate-based fine particles having no electromagnetic wave absorbing ability, composite fine particles of such materials, or the like can be used in combination. Such fine particles may be used alone or in combination.

  A conductive polymer as the second transparent resin component, or a conductive metal oxide, can be energized even in a minute region of the window where no metal nanowire exists, and can function as a complete surface electrode. In the present invention, it is essential to use a conductive metal oxide having electromagnetic wave absorbing ability for the first electrode, but a conductive polymer may be used in combination in order to function more as a surface electrode.

Thus, in order to work as a complete surface electrode, the surface resistance of the conductive material alone needs to be smaller than 10 ¹⁰ Ω / □, and more preferably 10 ⁸ Ω / □ or less.

  Examples of such conductive polymers include polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polyphenylacetylene, polydiacetylene, and polynaphthalene. The compound etc. which are chosen from the group which consists of each derivative can be mentioned.

(Formation method of the first electrode)
The method of forming the first electrode is not particularly limited, but if all the constituent materials are formed by a coating system, a so-called roll-to-roll process can be used, and the speed is higher with simpler equipment than when using a vacuum process. It is more preferable because continuous production is possible.

  In addition, after forming a layer containing metal nanowires, a transparent conductive metal oxide, and a conductive polymer on the release surface of a smooth release substrate, these layers are transferred onto the transparent substrate. It is preferable to use a method of forming a transparent electrode. In the organic photoelectric conversion element, the flatness of the first electrode is required. By using this method, it is possible to easily and stably highly smooth. Furthermore, by this method, a layer containing a metal nanowire, a conductive polymer having a relatively high refractive index, or a transparent conductive metal oxide can be placed on the side of the first electrode close to the organic photoelectric conversion layer (power generation layer). It becomes.

  Preferred examples of the releasable substrate used in the transparent electrode manufacturing method using this transfer process include a resin substrate and a resin film. There is no restriction | limiting in particular in this resin, It can select suitably from well-known things, For example, synthesis | combination, such as a polyethylene terephthalate resin, a vinyl chloride resin, an acrylic resin, a polycarbonate resin, a polyimide resin, a polyethylene resin, a polypropylene resin A substrate or film composed of a single layer or multiple layers of resin is preferably used. Furthermore, a glass substrate or a metal substrate can also be used. Further, the surface (release surface) of the releasable substrate may be subjected to a surface treatment by applying a release agent such as silicone resin, fluororesin, or wax as necessary.

  Since the surface of the releasable substrate affects the smoothness of the surface after the transparent conductive layer is transferred, it is desirable that the surface of the releasable substrate be highly smooth. Specifically, Ry ≦ 50 nm is preferable, and Ry ≦ 40 nm. More preferably, Ry ≦ 30 nm is still more preferable. Further, Ra ≦ 5 nm is preferable, Ra ≦ 3 nm is more preferable, and Ra ≦ 1 nm is still more preferable.

  In the present invention, Ry and Ra representing the smoothness of the surface of the transparent conductive layer mean Ry = maximum height (the difference in height between the top and bottom of the surface) and Ra = arithmetic mean roughness, JIS B601. It is a value according to the surface roughness specified in (1994). The transparent electrode of the present invention is characterized in that the surface smoothness of the transparent conductive layer is Ry ≦ 50 nm. In addition, the smoothness of the surface of the transparent conductive layer is preferably Ra ≦ 5 nm. In the present invention, for the measurement of Ry and Ra, a commercially available atomic force microscope (AFM) can be used. For example, it can be measured by the following method.

  Using an SPI 3800N probe station and SPA400 multifunctional unit manufactured by Seiko Instruments Inc. as the AFM, set the sample cut to a size of about 1 cm square on a horizontal sample stage on the piezo scanner, and place the cantilever on the sample surface. When approaching and reaching the region where the atomic force works, scanning is performed in the XY direction, and the unevenness of the sample at that time is captured by the displacement of the piezo in the Z direction. A piezo scanner that can scan XY 150 μm and Z 5 μm is used. The cantilever is a silicon cantilever SI-DF20 manufactured by Seiko Instruments Inc., which has a resonance frequency of 120 to 150 kHz and a spring constant of 12 to 20 N / m, and is measured in a DFM mode (Dynamic Force Mode). A measurement area of 80 × 80 μm is measured at a scanning frequency of 0.1 Hz.

  There is no particular limitation on the method for forming a layer containing metal nanowires, conductive polymer, and transparent conductive metal oxide on the release surface of the release substrate, but improvement in productivity, smoothness, uniformity, etc. From the viewpoint of improving the electrode quality and reducing the environmental load, it is preferable to use a liquid phase film forming method such as a coating method or a printing method. Application methods include roll coating, bar coating, dip coating, spin coating, casting, die coating, blade coating, bar coating, gravure coating, curtain coating, spray coating, and doctor coating. Etc. can be used. As the printing method, a letterpress (letter) printing method, a stencil (screen) printing method, a lithographic (offset) printing method, an intaglio (gravure) printing method, a spray printing method, an ink jet printing method, and the like can be used. In addition, as necessary, physical surface treatment such as corona discharge treatment or plasma discharge treatment can be applied to the surface of the releasable substrate as a preliminary treatment for improving the adhesion and coating properties.

  The first transparent resin component of the present invention may have this function as an adhesive when transferring onto a transparent substrate. For example, the above-described transparent resin may be used, and the adhesive is on the side of the releasable substrate. It may be provided on the transparent substrate side. The adhesive is not particularly limited as long as it is transparent in the visible region and has a transfer capability. As long as it is transparent, a curable resin or a thermoplastic resin may be used. Examples of curable resins include thermosetting resins, ultraviolet curable resins, and electron beam curable resins. Among these curable resins, the equipment for resin curing is simple and excellent in workability. It is preferable to use an ultraviolet curable resin. The ultraviolet curable resin is a resin that is cured through a crosslinking reaction or the like by ultraviolet irradiation, and a component containing a monomer having an ethylenically unsaturated double bond is preferably used. For example, acrylic urethane type resin, polyester acrylate type resin, epoxy acrylate type resin, polyol acrylate type resin and the like can be mentioned. In the present invention, it is preferable that an acrylic or acrylic urethane-based ultraviolet curable resin is a main component as a binder.

  Acrylic urethane-based resins generally include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter referred to as acrylates including methacrylates) to products obtained by reacting polyester polyols with isocyanate monomers or prepolymers. Can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate. For example, those described in JP-A-59-151110 can be used. For example, a mixture of 100 parts Unidic 17-806 (Dainippon Ink Co., Ltd.) and 1 part Coronate L (Nihon Polyurethane Co., Ltd.) is preferably used.

  Examples of UV curable polyester acrylate resins include those which are easily formed when 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers are generally reacted with polyester polyols. JP-A-59-151112 Can be used.

  Specific examples of the ultraviolet curable epoxy acrylate resin include an epoxy acrylate as an oligomer, a reactive diluent and a photoreaction initiator added to the oligomer, and a reaction. Those described in US Pat. No. 105738 can be used.

  Specific examples of UV curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

  Examples of the resin monomer having an ethylenically unsaturated double bond that is cured through a crosslinking reaction or the like by ultraviolet irradiation include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate, cyclohexyl as a monomer having an unsaturated double bond. Common monomers such as acrylate, vinyl acetate, and styrene can be listed. In addition, monomers having two or more unsaturated double bonds include ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, and the above-mentioned trimethylolpropane. Examples thereof include triacrylate and pentaerythritol tetraacryl ester.

  Among these, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane (meth) acrylate, trimethylolethane (meth) acrylate as the main component of the binder , An acrylic selected from dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate A system active ray curable resin is preferred.

  Specific examples of the photoinitiator of these ultraviolet curable resins include benzoin and its derivatives, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof. You may use with a photosensitizer. The photoinitiator can also be used as a photosensitizer. In addition, when using an epoxy acrylate photoinitiator, a sensitizer such as n-butylamine, triethylamine, or tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer used in the ultraviolet curable resin composition is 0.1 to 15 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the composition.

  The transparent conductive layer is made transparent by bonding (bonding) the release substrate formed with the transparent conductive layer and the transparent base material, curing the adhesive by irradiating ultraviolet rays and the like, and then peeling the release substrate. It can be transferred to the substrate side. Here, the bonding method is not particularly limited and can be performed by a sheet press, a roll press or the like, but is preferably performed using a roll press machine. The roll press is a method in which a film to be bonded is sandwiched between the rolls, and the rolls are rotated. The roll press is uniformly pressed and has higher productivity than the sheet press and can be used preferably.

(Patterning)
The first electrode according to the present invention may be patterned. There is no particular limitation on the patterning method and process, and a known method can be applied as appropriate. For example, a patterned transparent electrode can be formed by forming a layer containing a patterned metal nanowire, conductive polymer, or transparent conductive metal oxide on a release surface, and then transferring the layer onto a transparent substrate. Specifically, the following method can be preferably used.

i) A method of directly forming a layer containing a metal nanowire, a conductive polymer or a transparent conductive metal oxide in a pattern on a releasable substrate using a printing method.
ii) A method of uniformly forming a layer containing metal nanowires, a conductive polymer, or a transparent conductive metal oxide on a releasable substrate and then patterning using a general photolithography process
iii) A method of uniformly forming a layer containing, for example, a metal nanowire containing an ultraviolet curable resin, a conductive polymer or a transparent conductive metal oxide, and then patterning it like a photolithography process.
iv) A layer containing the metal nanowire, the conductive polymer, or the transparent conductive metal oxide according to the present invention is uniformly formed on a negative pattern previously formed of a photoresist on a releasable substrate, and a lift-off method is used. Patterning method.

  In any of the above methods, a patterned transparent electrode is formed by transferring a layer containing a metal nanowire, a conductive polymer or a transparent conductive metal oxide patterned on a releasable substrate onto a transparent substrate. can do.

(Second electrode)
The second electrode may be a single layer of conductive material, but in addition to a conductive material, a resin that holds these may be used in combination. As the conductive material for the second electrode, a material having a small work function (4 eV or less) metal, alloy, electrically conductive compound, or a mixture thereof is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃₎ mixture, indium, a lithium / aluminum mixture, and rare earth metals. Among these, in view of electron extraction performance and durability against oxidation, etc., a mixture of these metals and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, magnesium / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The counter electrode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

  If a metal material is used as the conductive material of the second electrode, the light coming to the second electrode side is reflected and reflected to the first electrode side, and this light can be reused and is absorbed again by the photoelectric conversion layer. It is preferable because the conversion efficiency is improved.

  In addition, the second electrode may be a metal (for example, gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, indium, etc.), carbon nanoparticles, nanowires, nanostructures, and nanowire dispersion. If it is a thing, a transparent and highly conductive counter electrode can be formed by the apply | coating method, and it is preferable.

  Moreover, when making the 2nd electrode side light-transmitting, after producing the electroconductive material suitable for 2nd electrodes, such as aluminum and aluminum alloy, silver, and a silver compound, with a film thickness of about 1-20 nm thinly, for example By providing a film of the conductive light transmissive material mentioned in the description of the transparent electrode, a light transmissive second electrode can be obtained.

(Organic photoelectric conversion element)
FIG. 2 is a cross-sectional view showing a solar cell composed of a bulk heterojunction organic photoelectric conversion element. In FIG. 2, the bulk heterojunction type organic photoelectric conversion element 10 has a transparent electrode 12, a photoelectric conversion layer portion 14 of a bulk heterojunction layer, and a counter electrode 13 sequentially stacked on one surface of a transparent substrate 11.

  The transparent substrate 11 is a member that holds the transparent electrode 12, the photoelectric conversion layer portion 14, and the counter electrode 13 that are sequentially stacked. In the present embodiment, since light that is photoelectrically converted enters from the transparent substrate 11 side, the transparent substrate 11 can transmit the light that is photoelectrically converted, that is, at the wavelength of the light to be photoelectrically converted. It is a transparent member. As the transparent substrate 11, for example, a glass substrate or a resin substrate is used. The transparent substrate 11 is not essential. For example, the bulk heterojunction organic photoelectric conversion element 10 may be configured by forming the transparent electrode 12 and the counter electrode 13 on both surfaces of the photoelectric conversion layer portion 14.

  It is necessary to use the first electrode of the present invention for the transparent electrode 12.

  The counter electrode 13 may be made of metal (for example, gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, indium, etc.), carbon, or the material of the transparent electrode 12, but is not limited thereto.

  In the bulk heterojunction organic photoelectric conversion element 10 shown in FIG. 2, the photoelectric conversion layer portion 14 is sandwiched between the transparent electrode 12 and the counter electrode 13, but the pair of comb-like electrodes is connected to the photoelectric conversion layer portion 14. The back contact type organic photoelectric conversion element 10 may be configured such that it is disposed on one side.

  The photoelectric conversion layer portion 14 is a layer that converts light energy into electric energy, and includes a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

(P-type semiconductor material)
Examples of the p-type semiconductor material used in the present invention include various condensed polycyclic aromatic compounds and conjugated compounds.

  As the condensed polycyclic aromatic compound, for example, anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, sarkham anthracene, bisanthene, zestrene, heptazelene, Examples thereof include compounds such as pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, and derivatives and precursors thereof.

  Examples of the conjugated compound include polythiophene and its oligomer, polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, tetrathiafulvalene compound, quinone Compounds, cyano compounds such as tetracyanoquinodimethane, fullerenes and derivatives or mixtures thereof.

  In particular, among polythiophene and oligomers thereof, thiophene hexamer α-seccithiophene, α, ω-dihexyl-α-secthiothiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3 Oligomers such as -butoxypropyl) -α-sexithiophene can be preferably used.

Further, porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF) -perchloric acid complex, BEDTTTTF-iodine complex, TCNQ-iodine complex, etc. Organic molecular complexes, fullerenes such as C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ and C ₈₄ , carbon nanotubes such as SWNT, dyes such as merocyanine dyes and hemicyanine dyes, and σ conjugates such as polysilane and polygermane Polymers and organic / inorganic hybrid materials described in JP 2000-260999 A can also be used.

  Among these π-conjugated materials, at least one selected from the group consisting of condensed polycyclic aromatic compounds such as pentacene, fullerenes, condensed ring tetracarboxylic acid diimides, metal phthalocyanines, and metal porphyrins is preferable.

  Examples of pentacenes include substituents described in International Publication No. 03/16599, International Publication No. 03/28125, US Pat. No. 6,690,029, Japanese Patent Application Laid-Open No. 2004-107216, and the like. A pentacene derivative described in U.S. Patent Application Publication No. 2003/136964 and the like; Amer. Chem. Soc. , Vol. 127. No. And substituted acenes described in 14.4986 and the like and derivatives thereof.

  Among these compounds, compounds that have high solubility in organic solvents to the extent that solution processing is possible, can form a crystalline thin film after drying, and can achieve high mobility are preferable. Such compounds include those described in J. Org. Amer. Chem. Soc. , Vol. 123, P9482; Amer. Chem. Soc. , Vol. 130 (2008), no. No. 9, 2706 and the like, acene-based compounds substituted with a trialkylsilylethynyl group, a pentacene precursor described in U.S. Patent Application Publication No. 2003/136964, etc., and Japanese Patent Application Laid-Open No. 2007-224019 Examples include precursor type compounds (precursors) such as porphyrin precursors. Among these, the latter precursor type can be preferably used. This is because the precursor type is insolubilized after conversion, so when forming a hole transport layer, electron transport layer, hole block layer, electron block layer, etc. on the bulk hetero junction layer by a solution process, bulk hetero junction This is because the layer does not dissolve and the material constituting the layer and the material forming the bulk heterojunction layer are not mixed, and further improvement in efficiency and life can be achieved. .

(N-type semiconductor material)
Examples of the n-type semiconductor material used in the present invention include fullerene C ₆₀ , fullerene C ₇₀ , fullerene C ₇₆ , fullerene C ₇₈ , fullerene C ₈₄ , fullerene C ₂₄₀ , fullerene C ₅₄₀ , mixed fullerene, fullerene nanotube, multilayer Nanotube, single-walled nanotube, nanohorn (conical), octaazaporphyrin, p-type semiconductor perfluoro (perfluoropentacene, perfluorophthalocyanine, etc.), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetracarboxylic Examples thereof include aromatic anhydrides such as acid anhydrides and perylenetetracarboxylic acid diimides, imidized products thereof, and polymer compounds containing these structures as a skeleton.

(Method for forming photoelectric conversion layer (power generation layer))
Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, a coating method is particularly preferable.

  The bulk heterojunction layer of the photoelectric conversion layer portion 14 is annealed at a predetermined temperature and partially microcrystallized during the manufacturing process in order to improve the photoelectric conversion rate.

  In FIG. 3, light incident from the transparent electrode 12 through the transparent substrate 11 is absorbed by the electron acceptor or electron donor in the bulk heterojunction layer of the photoelectric conversion layer portion 14, and electrons are transferred from the electron donor to the electron acceptor. Move to form a hole-electron pair (charge separation state). The generated electric charge is caused by an internal electric field, for example, when the work functions of the transparent electrode 12 and the counter electrode 13 are different, the electrons pass between the electron acceptors due to the potential difference between the transparent electrode 12 and the counter electrode 13, and the holes are , Passed between the electron donors and carried to different electrodes, and photocurrent is detected. For example, when the work function of the transparent electrode 12 is larger than the work function of the counter electrode 13, electrons are transported to the transparent electrode 12 and holes are transported to the counter electrode 13. If the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction. In addition, by applying a potential between the transparent electrode 12 and the counter electrode 13, the transport direction of electrons and holes can be controlled.

  The photoelectric conversion layer portion 14 may be composed of a single layer in which an electron acceptor and an electron donor are uniformly mixed, but a plurality of layers in which the mixing ratio of the electron acceptor and the electron donor is changed. It may be configured.

  Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, the coating method is preferable in order to increase the area of the interface where charges and electrons are separated from each other as described above and to produce a device having high photoelectric conversion efficiency. After application, it is preferable to perform heating in order to cause removal of residual solvent, moisture and gas, and chemical reaction of the semiconductor material as described above.

  The bulk heterojunction type organic photoelectric conversion element 10 includes a transparent electrode 12, a bulk heterojunction layer photoelectric conversion layer portion 14 and a counter electrode 13 which are sequentially stacked on a transparent substrate 11, but includes For example, there are other layers such as a hole transport layer, an electron transport layer, a hole block layer, an electron block layer, or a smoothing layer between the transparent electrode 12 or the counter electrode 13 and the photoelectric conversion layer portion 14. Then, the bulk heterojunction organic photoelectric conversion element 10 may be configured. Among these, a hole transport layer or an electron blocking layer is provided between the bulk heterojunction layer and the anode (usually the transparent electrode 12 side), and an electron transport layer or an electron blocking layer is provided between the cathode (usually the counter electrode 13 side). By forming the hole blocking layer, the charges generated in the bulk heterojunction layer can be taken out more efficiently. Therefore, it is preferable to have these layers.

  As a material constituting these layers, for example, as a hole transporting layer (electron block layer), PEDOT such as Startron Vitec, trade name BaytronP, polyaniline and its doped material, Japanese Patent Laid-Open No. 5-271166 The triarylamine compounds described in the above, the cyan compounds described in the pamphlet of WO2006 / 019270, and metal oxides such as molybdenum oxide, nickel oxide, and tungsten oxide can be used. A layer made of a single p-type semiconductor material used for the bulk heterojunction layer can also be used. The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method.

  As the electron transport layer (hole blocking layer), octaazaporphyrin, p-type semiconductor perfluoro (perfluoropentacene, perfluorophthalocyanine, etc.), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetra N-type semiconductor materials such as carboxylic acid anhydrides and perylenetetracarboxylic acid diimides, and n-type inorganic oxides such as titanium oxide, zinc oxide and gallium oxide, and alkali metal compounds such as lithium fluoride, sodium fluoride and cesium fluoride Etc. can be used. A layer made of a single n-type semiconductor material used for the bulk heterojunction layer can also be used. The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method.

  Furthermore, it is good also as a tandem-type structure which laminated | stacked such a photoelectric conversion element for the purpose of the improvement of sunlight utilization factor (photoelectric conversion efficiency). FIG. 3 is a cross-sectional view showing a solar cell composed of a bulk heterojunction organic photoelectric conversion element including a tandem bulk hetero layer. In the case of the tandem configuration, after the transparent electrode 12 and the first photoelectric conversion layer portion 14 are sequentially stacked on the transparent substrate 11, the charge recombination layer 15 is stacked, and then the second photoelectric conversion layer portion 16 and then the counter electrode. By stacking 13, a tandem configuration can be obtained. The second photoelectric conversion layer portion 16 may be a layer that absorbs the same spectrum as the absorption spectrum of the first photoelectric conversion layer portion 14 or may be a layer that absorbs a different spectrum, but is preferably a layer that absorbs a different spectrum. . Further, the material of the charge recombination layer 15 is preferably a layer using a compound having both transparency and conductivity, such as transparent metal oxides such as ITO, AZO, FTO, and titanium oxide, Ag, Al, A very thin metal layer such as Au, or a conductive polymer material such as PEDOT: PSS or polyaniline is preferable.

  Moreover, it is preferable to seal by the well-known method so that the produced organic photoelectric conversion element 10 does not deteriorate with oxygen, moisture, etc. in the environment. For example, a method of sealing a cap made of aluminum or glass by bonding with an adhesive, a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed, and the organic photoelectric conversion element top 10 with an adhesive. A method of bonding, a method of spin-coating an organic polymer material with high gas barrier properties (polyvinyl alcohol, etc.), a method of directly depositing an inorganic thin film with high gas barrier properties (silicon oxide, aluminum oxide, etc.), and a combination of these The method of laminating can be mentioned.

(Electromagnetic radiation)
A microwave can be preferably used for the electromagnetic wave in the present invention.

  In the present invention, a photoelectric conversion layer portion (power generation layer portion) coating step of coating a solution containing at least a semiconductor material and / or a semiconductor material precursor on the first electrode, and a photoelectric conversion layer portion are coated. A characteristic is that an organic photoelectric conversion element is formed by irradiating a member with microwaves. In the present invention, it is necessary that at least the conductive metal oxide contained in the first electrode absorbs microwaves. The microwave irradiation may be a member in which the photoelectric conversion layer portion is coated on the first electrode of the present invention. After the photoelectric conversion layer portion is coated and the residual solvent in the photoelectric conversion layer portion is removed, the first irradiation is performed. It may be after two electrodes are provided.

  The microwave irradiation device used in the present invention can be applied from a relatively low frequency device of 0.3 GHz to a high frequency device of 50 GHz, but more preferably 2.45 to 28 GHz. When using low-frequency microwaves, use a well-known method such as installing a heat sink or a low-loss material that does not easily transmit microwaves in the vicinity of the microwave irradiated object in order to perform uniform heating. Can do.

There is no particular designation as an atmosphere for irradiating microwaves, and there is no particular designation in the atmosphere of an inert gas such as N ₂ or Ar, in the air, or a reducing gas such as Ar + H _2, but it may be performed in an inert gas. More preferred.

  In addition, in microwave irradiation, heat may be transferred to the base material due to heat conduction. Especially in the case of a base material with low heat resistance such as a resin substrate, the output of microwave, irradiation time, and further irradiation. By controlling the number of times, the substrate temperature is preferably 50 to 200 ° C., and the surface temperature of the first electrode containing the conductive metal oxide is preferably 150 to 200 ° C. The surface temperature of the thin film, the temperature of the substrate, etc. can be measured with a surface thermometer using a thermocouple.

  By this heat generation, in the organic photoelectric conversion element, the necking between the metal nanowires of the first electrode is promoted to improve the electrode performance, and the annealing process of the power generation layer part (photoelectric conversion layer part) can be performed. It is believed that the annealing process changes the state of the semiconductor material (for example, the crystalline state) and improves the photoelectric conversion efficiency.

  Generally, a microwave refers to an electromagnetic wave having a frequency of 0.3 to 50 GHz, and is used in 0.8 MHz and 1.5 GHz band, 2 GHz band, amateur radio, aircraft radar, etc. used in mobile communication. .2 GHz band, microwave oven, local radio, 2.4 GHz band used for VICS, 3 GHz band used for ship radar, etc., and 5.6 GHz used for other ETC communications are all electromagnetic waves in the microwave category. is there.

  In the field of ceramics, it is already known to use such electromagnetic waves for sintering. When a material containing magnetism is irradiated with an electromagnetic wave, heat can be generated in accordance with the size of the loss portion of the complex permeability of the substance, and the temperature can be increased uniformly and in a short time. On the other hand, it is well known that when a metal is irradiated with microwaves, free electrons start to move at a high frequency, so that arc discharge occurs and heating cannot be performed.

  Based on such a background, the inventors heat the conductive metal oxide or conductive metal oxide precursor having electromagnetic wave absorbing ability of the present invention to a high temperature in a short time and uniformly. .

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Organic photoelectric conversion element STC-1 >>
ITO was vapor-deposited with an average film thickness of 150 nm on a PEN film having a barrier layer (total light transmittance of 90%) to produce a first electrode TC-1.

  On the first electrode TC-1, a conductive polymer PEDOT / PSS (poly (3,4-ethylenedithiophene) -poly (styrenesulfonate)) (Baytron P4083, manufactured by HC Starck) with a film thickness of 30 nm. After spin coating, it was dried by heating at 140 ° C. in the air for 10 minutes.

  After this, the substrate was brought into the glove box and worked under a nitrogen atmosphere. First, the substrate was heat-treated at 180 ° C. for 3 minutes in a nitrogen atmosphere.

  Next, P3HT (poly-3-hexylthiophene) (manufactured by Reike Metal; Mn = 45000, regioregular type, polymer p-type semiconductor material) 1.0% by mass in chlorobenzene, PCBM (6,6-phenyl-C61-butylene) (Liquid Methyl Ester) (Mw = 911, low molecular weight n-type semiconductor material) 1.0 mass% solution was prepared and filtered through a 0.45 μm filter for 60 seconds at 500 rpm, then for 1 second at 2200 rpm. Spin coating was performed, and the mixture was allowed to stand at room temperature for 30 minutes and then heated at 160 ° C. for 30 minutes.

Next, the first electrode on which the series of organic power generation layer portions was formed was placed in a vacuum evaporation apparatus. After depressurizing the inside of the vacuum deposition apparatus to 10 ⁻³ Pa or less, Al was deposited by 80 nm to obtain an organic photoelectric conversion element STC-1 having a size of 2 mm square.

  The obtained organic photoelectric conversion element STC-1 is a flexible material in which polyethylene terephthalate is used as a base material by applying an adhesive around the cathode electrode except for the ends so that external lead terminals of the anode electrode and the cathode electrode can be formed. After bonding the conductive sealing member, the adhesive was cured by heat treatment.

<< Photoelectric Conversion Element STC-2 >>
In the production of the photoelectric conversion element-1, P3HT (poly-3-hexylthiophene) (manufactured by Reike Metal; Mn = 45000, regioregular type, polymer p-type semiconductor material) 1.0% by mass, PCBM (6, 6) Spin-coating a solution in which 1.0% by mass of -phenyl-C61-butyric acid methyl ester) (Mw = 911, low-molecular n-type semiconductor material) was spin-coated, left at room temperature for 30 minutes, and then at 160 ° C. for 30 minutes Instead of heat treatment, using a thermocouple surface thermometer in an atmospheric pressure atmosphere, the device was heated to 160 ° C. at 500 W output, and then microwave irradiation was performed while PID control of the microwave output was performed. The temperature was kept at 160 ° C. and heated for 30 minutes.

<< Organic photoelectric conversion element STC-3 >>
(Adjustment of metal nanowires)
In this example, silver nanowires were used as metal nanowires. Silver nanowires are described in Adv. Mater. , 2002, 14, 833 to 837, silver nanowires having an average diameter of 75 nm and an average length of 35 μm were prepared, and the silver nanowires were filtered and washed with an ultrafiltration membrane, followed by ethanol. It was re-dispersed in a silver nanowire (AgNW) dispersion (silver nanowire content 5 mass%).

(Production of the first electrode TC-3)
A biaxially stretched PET film was used as the releasable substrate. After the corona discharge treatment was applied to the surface of the PET film, the silver nanowire dispersion was applied using an applicator so that the basis weight of the silver nanowire was 80 mg / m ² and dried to form a silver nanowire network structure. .

  Further, using the following transparent inorganic component-containing liquid A-1 as the second transparent resin component, the silver nanowire network structure was overcoated and dried so that the dry film thickness was 200 nm, and then heat treated at 80 ° C. for 3 hours. did. This is an AgNW-containing film for transfer.

  Next, the following UV curable transparent resin liquid 1 was applied as a first transparent resin component on a PEN film (total light transmittance 90%) having a barrier layer and an easy-adhesion layer so as to have a thickness of 5 μm, and then the above transfer It was pasted with an AgNW-containing film. Subsequently, after the first transparent resin component is sufficiently cured by irradiating with ultraviolet rays, the layer formed on the transfer AgNW-containing film is formed on the PEN film by peeling off the PET film which is a releasable substrate. After the transfer, a first electrode TC-3 according to the present invention was produced.

<Transparent inorganic component-containing liquid A-1>
Sb-doped SnO ₂ fine particles (SN100D manufactured by Ishihara Sangyo Co., Ltd., solid content 30%)
160g
Compound (UL-1) 0.2g
Modified polyester A (solid content 18%) 30 g
Finish up to 1000 ml with water.

<Synthesis of modified aqueous polyester A>
In a reaction vessel for polycondensation, 35.4 parts by mass of dimethyl terephthalate, 33.63 parts by mass of dimethyl isophthalate, 17.92 parts by mass of 5-sulfo-isophthalic acid dimethyl sodium salt, 62 parts by mass of ethylene glycol, calcium acetate monohydrate 0.065 parts by mass of salt and 0.022 parts by mass of manganese acetate tetrahydrate were added, and the ester exchange reaction was performed while distilling off methanol at 170 to 220 ° C. in a nitrogen stream. 04 parts by mass, 0.04 parts by mass of antimony trioxide as a polycondensation catalyst and 6.8 parts by mass of 1,4-cyclohexanedicarboxylic acid were added, and a theoretical amount of water was distilled off at a reaction temperature of 220 to 235 ° C. Esterification was performed. Thereafter, the reaction system was further depressurized and heated for about 1 hour, and finally subjected to polycondensation at 280 ° C. and 133 Pa or less for about 1 hour to obtain a modified aqueous polyester A precursor. The intrinsic viscosity of the precursor was 0.33.

  850 ml of pure water was put into a 2 L three-necked flask equipped with a stirring blade, a reflux condenser, and a thermometer, and 150 g of the precursor was gradually added while rotating the stirring blade. After stirring for 30 minutes at room temperature, the mixture was heated to an internal temperature of 98 ° C. over 1.5 hours, and heated and dissolved at this temperature for 3 hours. After completion of the heating, the mixture was cooled to room temperature over 1 hour and left overnight to prepare a solution having a solid content concentration of 15% by mass.

  1900 ml of the precursor solution was placed in a 3 L four-necked flask equipped with a stirring blade, a reflux condenser, a thermometer, and a dropping funnel, and the internal temperature was heated to 80 ° C. while rotating the stirring blade. Into this, 6.52 ml of a 24% aqueous solution of ammonium persulfate was added, and a monomer mixture (28.5 g of glycidyl methacrylate, 21.4 g of ethyl acrylate, 21.4 g of methyl methacrylate) was dropped over 30 minutes. The reaction was continued for another 3 hours. Then, it cooled to 30 degrees C or less, and filtered, and prepared the solution of the modified aqueous polyester A whose solid content concentration is 18 mass% (polyester component / acrylic component = 80/20).

<UV curing transparent resin liquid 1>
SP-1 (manufactured by Asahi Denka) 3 parts by mass EP-1 20 parts by mass OXT221 (manufactured by Toagosei) 40.4 parts by mass OXT212 (manufactured by Toagosei) 25 parts by mass OXT101 (manufactured by Toagosei) 3 parts by mass propylene carbonate 3 parts by mass Parts Triisopropanolamine 0.1 parts by weight X-22-4272 (manufactured by Shin-Etsu Silicone) 0.5 parts by weight

(Preparation of organic photoelectric conversion element STC-3)
Organic photoelectric conversion element STC-3 was prepared in the same manner except that the first electrode was changed from TC-1 to TC-3 in preparation of organic photoelectric conversion element STC-2.

<< Photoelectric Conversion Element STC-4 >>
(Preparation of the first electrode TC-4)
In TC-3, the transparent electrode TC- was similarly used except that the transparent inorganic component-containing liquid A-2 was used instead of the transparent inorganic component-containing liquid A-1 and the dry film thickness was 200 nm. 4 was produced.

<Transparent inorganic component-containing liquid A-2>
SnO ₂ sol (Cerames S-8, manufactured by Taki Chemical Co., Ltd., solid content 8%)
160g
Compound (UL-1) 0.2g
Modified polyester A (solid content 18%) 30 g
Finish up to 1000 ml with water.

(Preparation of organic photoelectric conversion element STC-4)
Organic photoelectric conversion element STC-4 was prepared in the same manner except that the first electrode was changed from TC-3 to TC-4.

<< Photoelectric Conversion Element STC-5 >>
(Production of the first electrode TC-5)
In the preparation of TC-3, the conductive fiber was changed to a dispersion of SWCNT (Unipym, HiPcoR single-walled carbon nanotube), and the same was applied except that the coating amount of SWCNT was 5 mg / m ² respectively. Thus, TC-5 was prepared.

(Preparation of organic photoelectric conversion element STC-5)
Organic photoelectric conversion element STC-5 was prepared in the same manner except that the first electrode was changed from TC-3 to TC-5 in preparation of organic photoelectric conversion element STC-3.

[Evaluation of organic photoelectric conversion elements]
<< Evaluation of organic photoelectric conversion element: photoelectric conversion efficiency >>
An organic photoelectric conversion element sealed with a glass sealing cap and a UV curable resin is irradiated with light from a solar simulator (AM1.5G) at an intensity of 100 mW / cm ² to obtain voltage-current characteristics. The photoelectric conversion efficiency (η) (%) was determined from the analysis of open circuit voltage (Voc) (V), short circuit current density (Jsc) (mA / cm ² ), and fill factor (FF).

《Bending resistance (Retention degree of energy conversion efficiency after bending)》
The change of the energy conversion efficiency before and after winding the obtained organic photoelectric conversion element around the front and back 50 times on a 1 inchφ (1 inch is 2.54 cm) rod was wound around the energy conversion efficiency before winding. The subsequent energy conversion efficiency was calculated as the retention rate and is shown in Table 1.

Retention rate = energy conversion efficiency after winding / energy conversion efficiency after winding × 100 (%)
The evaluation results are shown in Table 1.

  From Table 1, this invention which irradiated the microwave to the organic photoelectric conversion element using the 1st electrode containing the electroconductive metal oxide and / or electroconductive metal oxide (precursor) which have electromagnetic wave absorptivity is high photoelectric conversion It has been found that it has efficiency and has improved bending resistance. In particular, it has been found that a more preferable effect can be obtained with the first electrode using a combination of Ag nanowire which is a conductive fiber and a conductive metal oxide having electromagnetic wave absorbing ability.

Example 2
<< p-type semiconductor material >>
The following tetrabenzoporphyrin derivative was used as a p-type semiconductor material.

<< Organic photoelectric conversion elements STC-21 to 25 >>
In the production of organic photoelectric conversion elements STC-1 to STC-5, organic photoelectric conversion elements STC-21 to 25 are similarly performed except that 1.2% by mass of BP-1 is used instead of 1.0% by mass of P3HT. Was made.

  When evaluated in the same manner as in Example 1, it was confirmed that the effects of the present invention were obtained.

It is a structural schematic diagram of the 1st electrode which has a transparent conductive layer of this invention. It is sectional drawing which shows the solar cell which consists of a bulk heterojunction type organic photoelectric conversion element. Cross section It is sectional drawing which shows the solar cell which consists of a bulk heterojunction type organic photoelectric conversion element provided with a tandem type bulk hetero layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal nanowire 2 2nd transparent resin component containing part or transparent inorganic component containing part 3 1st transparent resin 4 1st electrode 5 Transparent base material 6 Conductive metal oxide 10 Organic photoelectric conversion element 11 Transparent substrate 12 Transparent electrode 13 Counter electrode 14, 16 Photoelectric conversion layer 15 Charge recombination layer

Claims (5)

A first electrode having a transparent conductive layer comprising at least a conductive fiber and a conductive metal oxide on a transparent substrate; a photoelectric conversion layer portion comprising a p-type semiconductor material and an n-type semiconductor material; In the method for producing an organic photoelectric conversion element having two electrodes, a solution containing at least one type of conductive fiber and a solution containing at least one type of conductive metal oxide having electromagnetic wave absorbing ability are coated on a transparent substrate. By a process having at least a step of coating the first electrode composition, a step of coating the photoelectric conversion layer portion on the first electrode, and a step of irradiating the member on which the photoelectric conversion layer portion is coated with electromagnetic waves A method for producing an organic photoelectric conversion element produced by the method. The method for producing an organic photoelectric conversion element according to claim 1, wherein the electromagnetic wave is a microwave. The method for producing an organic photoelectric conversion element according to claim 1, wherein the conductive fiber is at least one selected from the group consisting of metal nanowires and carbon nanotubes. The method for producing an organic photoelectric conversion element according to claim 1, wherein the conductive metal oxide is tin oxide and / or tin oxide sol. An organic photoelectric conversion element produced by the method for producing an organic photoelectric conversion element according to claim 1.

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