JP2012069803A - Organic thin-film solar cell and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible and transparent bulk-heterojunction organic thin-film solar cell whose power generation efficiency is less likely to be deteriorated over time.SOLUTION: The organic thin-film solar cell comprises a first transparent electrode 18, an electron block layer 20, a bulk-heterojunction photoelectric conversion layer 22, a first transparent inorganic oxide layer 24, a second transparent electrode containing a doped second transparent inorganic oxide layer 26, in this order on a plastic film substrate 12.

Description

  The present invention relates to an organic thin film solar cell and a method for producing the same.

In recent years, organic electronic devices that can be expected to be low-cost, lightweight, and flexible have attracted attention. In particular, a bulk hetero-type organic thin film solar cell using a plastic film substrate can obtain relatively high power generation efficiency, and is expected to be put to practical use.
In the bulk hetero type organic thin film solar cell, a bulk heterojunction type photoelectric conversion layer (referred to as “bulk hetero layer” as appropriate) is formed by mixing an electron transport material and a hole transport material between two different electrodes. It will be. The bulk hetero type organic thin film solar cell has a feature that light absorption characteristics can be adjusted. For this reason, unlike a solar cell using an inorganic semiconductor, a transparent solar cell can be manufactured.

  In the organic thin film solar cell, the electrode on the substrate side (usually the positive electrode) is transparent. In order for the organic thin film solar cell to be transparent, the second transparent electrode (usually the negative electrode) must also be transparent. As an example of a transparent organic thin film solar cell, Patent Document 1 discloses an element having a hybrid electrode of ITO (indium-tin oxide) and an Ag—Mg thin film as a counter electrode. However, since the Ag—Mg thin film is easily corroded, it has a drawback that the power generation efficiency of the solar cell decreases with time. This drawback becomes a more prominent problem when a plastic film substrate having a low water vapor barrier property is used.

Moreover, in patent document 2, as a transparent conductive film used for various devices, on the transparent film base material, the 1st auxiliary electrode comprised from the metal pattern which has an opening part, and the opening part of a 1st auxiliary electrode A transparent auxiliary electrode film having a conductive structure composed of a second auxiliary electrode containing conductive fibers is disclosed.
Non-Patent Document 1 discloses an organic solar cell in which an ITO layer, a PEDOT: PSS layer, a photoelectric conversion layer, a titanium oxide (TiO _x ) layer, and an aluminum layer are sequentially provided on a glass substrate.

US Pat. No. 6,657,378 JP 2009-146747 A

Advanced Materials 2007, Vol. 19, pp. 2445-2449

  When manufacturing a transparent organic thin-film solar cell having a bulk hetero layer, each layer other than the photoelectric conversion layer needs to have optical transparency, but the bulk hetero layer is an organic compound and thus is easily damaged. Therefore, when a transparent electrode such as ITO is formed as a transparent electrode on the bulk hetero layer, for example, by sputtering, the bulk hetero layer is damaged, and the power generation efficiency is likely to decrease during long-term use.

  An object of the present invention is to provide a bulk hetero-type organic thin film solar cell that is flexible and transparent in which power generation efficiency is unlikely to decrease with time.

In order to achieve the above object, the following invention is provided.
<1> On a plastic film substrate, a first transparent electrode, an electron block layer, a bulk heterojunction photoelectric conversion layer, a first transparent inorganic oxide layer, and a doped second transparent inorganic oxide The organic thin-film solar cell which has a 2nd transparent electrode containing a layer in this order.
<2> The organic thin-film solar cell according to claim 1, wherein the second transparent inorganic oxide layer contains titanium oxide or zinc oxide as a main component.
<3> The organic thin-film solar cell according to <1> or <2>, wherein the second transparent inorganic oxide layer has a thickness of 50 nm to 400 nm.
<4> The first transparent inorganic oxide layer according to any one of <1> to <3>, including at least one inorganic oxide selected from the group consisting of titanium oxide, zinc oxide, and tin oxide. Organic thin film solar cell.
<5> The organic thin-film solar cell according to any one of <1> to <4>, wherein a film thickness of the first transparent inorganic oxide layer is 1 nm to 30 nm.
<6> The organic thin-film solar cell according to any one of <1> to <5>, wherein the visible light transmittance of the second transparent inorganic oxide layer is 50% or more.
<7> The organic thin-film solar cell according to any one of <1> to <6>, having a bus line on the second transparent electrode.
<8> The organic thin-film solar cell according to any one of <1> to <7>, having a bus line between the first transparent inorganic oxide layer and the second transparent electrode.
<9> The organic thin-film solar cell according to any one of <1> to <8>, having a protective layer on the second transparent electrode.
<10> The organic thin-film solar cell according to <9>, wherein the protective layer contains an inorganic oxide or an inorganic nitride as a main component.
<11> The first transparent electrode according to any one of <1> to <10>, wherein the first transparent electrode includes a conductive mesh and a conductive polymer layer disposed in at least an opening of the conductive mesh and in contact with the conductive mesh. Organic thin film solar cell.
<12> The organic thin-film solar cell according to <11>, wherein the conductive mesh includes silver.
<13> The organic thin-film solar cell according to <11> or <12>, wherein the conductive mesh includes silver and a hydrophilic polymer.
<14> The organic thin-film solar cell according to any one of <11> to <13>, wherein a line width in a plan view of the conductive mesh is 1 μm or more and 20 μm or less.
<15> The organic thin-film solar cell according to any one of <11> to <14>, wherein a pitch of the conductive mesh in plan view is 50 μm or more and 500 μm or less.
<16> The organic thin film solar according to any one of <11> to <15>, wherein an area of an opening serving as a repeating unit in the conductive mesh is 1 × 10 ⁻⁸ m ² or more and 1 × 10 ⁻⁷ m ² or less. battery.
<17> The organic thin-film solar cell according to any one of <11> to <16>, wherein the conductive polymer layer contains a polythiophene derivative.
<18> The organic thin-film solar cell according to <17>, wherein the polythiophene derivative has a volume resistivity of 1 × 10 ⁻² Ωcm or less.
<19> The organic thin-film solar cell according to <17> or <18>, wherein the polythiophene derivative is polyethylenedioxythiophene.
<20> The organic thin-film solar cell according to any one of <1> to <19>, wherein the bulk heterojunction photoelectric conversion layer contains a fullerene derivative.
<21> The organic thin-film solar pond according to any one of <1> to <20>, wherein the bulk heterojunction photoelectric conversion layer contains 50% by mass or more of an electron transport material.
<22> a step of forming a first transparent electrode including a conductive mesh on a plastic film substrate and a conductive polymer layer disposed in at least an opening of the conductive mesh and in contact with the conductive mesh; and the first transparent electrode And a step of sequentially forming an electron blocking layer, a photoelectric conversion layer, a first transparent inorganic oxide layer, and a second transparent electrode containing a doped second transparent inorganic oxide. Manufacturing method of organic thin-film solar cell.
<23> The method for producing an organic thin-film solar cell according to <22>, wherein the first transparent inorganic oxide layer is formed by a wet film formation method.
<24> A step of pattern exposure of the conductive mesh on the plastic film substrate to a coating film for forming the conductive mesh, a step of developing the pattern-exposed coating film, and the development The method for producing an organic thin-film solar cell according to <22> or <23>, wherein the method comprises:

  According to the present invention, it is possible to provide a bulk hetero-type organic thin-film solar cell that is flexible and transparent in which power generation efficiency is unlikely to decrease with time.

It is a schematic sectional drawing which shows an example of the structure of the organic thin film solar cell of this invention. It is a schematic plan view which shows the one aspect | mode of the electrically conductive mesh in the organic thin film solar cell of this invention.

  Hereinafter, the bulk hetero type organic thin film solar cell of the present invention (hereinafter sometimes abbreviated as the organic solar cell of the present invention) will be described in detail. In the specification of the present application, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

  As a result of intensive studies by the present inventors to achieve the object of the present invention, a transparent inorganic oxide layer was formed on the bulk hetero layer without damaging the bulk hetero layer as much as possible. It was found that the object of the present invention can be achieved by forming a transparent inorganic oxide thin film doped as a negative electrode.

FIG. 1 schematically shows a cross section of one embodiment of the organic solar cell of the present invention.
The organic solar cell 10 of the present invention includes a plastic film substrate 12, a first transparent electrode 18, an electron block layer 20, and a bulk heterojunction photoelectric conversion layer (bulk hetero layer) on the plastic film substrate 12. 22, a first transparent inorganic oxide layer 24, and a second transparent electrode including a doped second transparent inorganic oxide layer 26 in this order.
The organic solar cell 10 of the present invention includes a hole blocking layer, an electron blocking layer, an exciton diffusion preventing layer, a hole transport layer, an electron transport layer, a hole trapping layer, an electron trapping layer, and an easy adhesion layer as necessary. Further, a known layer such as a protective layer, a conductive layer, a gas barrier layer, a matting agent layer, an antireflection layer, a hard coat layer, an antifogging layer, or an antifouling layer may be further provided.
Hereinafter, the components of the organic solar cell of the present invention will be described in detail.

<Plastic film substrate>
The plastic film substrate 12 used in the organic solar cell of the present invention is light-transmissive and can be made of a material, as long as it can hold a first transparent electrode, a bulk hetero layer, a second transparent electrode, and the like described later. There is no restriction | limiting in particular in thickness etc., According to the objective, it can select suitably.

Specific examples of the material of the plastic film 12 used as the support substrate include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, transparent fluororesin, polyimide, fluorinated polyimide resin, and polyamide resin. , Polyamideimide resin, polyetherimide resin, cellulose acylate resin, polyurethane resin, polyetheretherketone resin, polycarbonate resin, cycloaliphatic polyolefin resin, polyarylate resin, polyethersulfone resin, polysulfone resin, cycloolefin copolymer, Examples thereof include thermoplastic resins such as a fluorene ring-modified polycarbonate resin, an alicyclic ring-modified polycarbonate resin, a fluorene ring-modified polyester resin, and an acryloyl compound.
The plastic film substrate 12 is preferably made of a material having heat resistance. Specifically, it is preferable that the glass transition temperature (Tg) is molded from a material satisfying any physical property of 60 ° C. or higher or a linear thermal expansion coefficient of 40 ppm / ° C. or lower.
The Tg and linear expansion coefficient of the plastic film are measured by the plastic transition temperature measurement method described in JIS K 7121 and the linear expansion coefficient test method based on the thermomechanical analysis of plastic described in JIS K 7197. In, the value measured by this method is used.

  The Tg and the linear expansion coefficient of the plastic film substrate 12 can be adjusted by an additive or the like. Examples of such a thermoplastic resin having excellent heat resistance (the temperature in parentheses indicates Tg), for example, polyethylene terephthalate (PET: 65 ° C.), polyethylene naphthalate (PEN: 120 ° C.), polycarbonate (PC: 140 ° C), alicyclic polyolefin (for example, ZEONOR 1600: 160 ° C manufactured by Nippon Zeon Co., Ltd.), polyarylate (PAr: 210 ° C), polyethersulfone (PES: 220 ° C), polysulfone (PSF: 190 ° C), cyclo Olefin copolymer (COC: compound described in JP 2001-150584 A: 162 ° C.), fluorene ring-modified polycarbonate (BCF-PC: compound described in JP 2000-227603 A: 225 ° C.), Alicyclic modified polycarbonate (IP-PC) 000-227603 publication: 205 ° C.), acryloyl compound (Japanese Unexamined Patent Publication No. 2002-80616 publication: 300 ° C. or higher), polyimide, and the like. It is suitable as a material (support). Especially, it is preferable to use alicyclic polyolefin etc. especially for the use for which transparency is required.

The plastic film 12 used as the support substrate is required to be transparent to light. More specifically, it is desirable that the light transmittance with respect to light in the wavelength range of 400 nm to 800 nm is high, usually 80% or more, more preferably 85% or more, and further preferably 90% or more. The light transmittance is calculated by measuring the total light transmittance and the amount of scattered light using the method described in JIS-K7105, that is, an integrating sphere light transmittance measuring device, and subtracting the diffuse transmittance from the total light transmittance. be able to.
Although there is no restriction | limiting in particular regarding the thickness of the plastic film 12, Typically, they are 1 micrometer-800 micrometers, Preferably they are 10 micrometers-300 micrometers.
A known functional layer may be provided on the back surface (the surface on which the first transparent electrode is not provided) of the plastic film 12. Examples of the functional layer include a gas barrier layer, a mat agent layer, an antireflection layer, a hard coat layer, an antifogging layer, and an antifouling layer. In addition, the functional layer is described in detail in paragraph numbers [0036] to [0038] of JP-A-2006-289627.

<Easily adhesive layer / undercoat layer>
The surface of the plastic film substrate 12 (the surface on which the first transparent electrode is provided) may have an easy-adhesion layer or an undercoat layer from the viewpoint of improving adhesion. The easy adhesion layer or the undercoat layer may be a single layer or a multilayer.
Various hydrophilic undercoat polymers are used to form the easy-adhesion layer or the undercoat layer. Examples of hydrophilic undercoat polymers used in the present invention include gelatin, gelatin derivatives, casein, agar, sodium alginate, starch, polyvinyl alcohol and other water-soluble polymers, carboxymethyl cellulose, cellulose esters such as hydroxyethyl cellulose, and vinyl chloride-containing copolymers. Examples include latex polymers such as vinylidene chloride-containing copolymers, acrylate-containing copolymers, vinyl acetate-containing copolymers, and butadiene-containing copolymers, polyacrylic acid copolymers, and maleic anhydride copolymers. Is done.
The coating film thickness after drying the easy-adhesion layer or the undercoat layer is preferably in the range of 50 nm to 2 μm. In addition, when using a support body as a temporary support body, it is also possible to give an easily peelable process to the support surface.

<First transparent electrode>
The first transparent electrode 18 disposed on the plastic film substrate 12 includes a transparent conductive inorganic oxide (for example, indium-tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide). (ATO), group 13 element (eg, zinc oxide doped with B, Al, Ga, In), etc., conductive mesh (eg, silver mesh, copper mesh), conductive polymer (eg, polyaniline, polythiophene, polypyrrole), or It is comprised by these combinations.
The first transparent electrode in the present invention preferably includes a conductive mesh and a conductive polymer from the viewpoint of achieving high light transmittance and conductivity. In order to combine the conductive mesh and the conductive polymer to form the first transparent electrode, for example, the conductive mesh 14 is provided on the plastic film substrate 12, and then the conductive mesh 14 is in contact with the conductive mesh 14 at least in the opening of the conductive mesh 14. A polymer layer 16 may be provided. The conductive polymer layer 16 is preferably formed on the conductive mesh 14 in addition to the opening of the conductive mesh 14.
In the present invention, the first transparent electrode 18 including the conductive mesh 14 and the conductive polymer layer 16 functions as a positive electrode (cathode) of the bulk hetero type organic solar cell.

(Conductive mesh)
In the present invention, the conductive mesh 14 is formed of various metal materials. Examples of the metal material include gold, platinum, iron, copper, silver, aluminum, chromium, cobalt, and stainless steel. Preferable examples of the metal material include low resistance metals such as copper, silver, aluminum, and gold. Among them, silver or copper having excellent conductivity is preferably used.
There is no particular limitation on the mesh pattern. Stripes, squares, rectangles, diamonds, honeycombs, or curves may be used. FIG. 2 schematically shows an example of a square mesh network pattern.

The shape, line width, pitch, and the like of the conductive mesh 14 are adjusted so that the aperture ratio (light transmittance) and the surface resistance (conductivity) have desired values. In FIG. 2, a region 15 surrounded by the conductive mesh 14 represents an opening, and the opening ratio is preferably 70% or more, more preferably 80% or more, and particularly preferably 85% or more.
The surface resistance of the conductive mesh in a state where no conductive polymer is provided is preferably 10 Ω / sq or less, more preferably 3 Ω / sq or less, and even more preferably 1 Ω / sq or less. Since the light transmittance and the conductivity are in a trade-off relationship, the larger the aperture ratio, the better. However, in practice, it is preferably 95% or less.

  The thickness of the conductive mesh 14 is not particularly limited, but is usually 0.02 μm or more and 20 μm or less. Further, the line width of the thin metal wire constituting the conductive mesh in a plan view is in the range of 1 μm to 500 μm, preferably 1 μm to 100 μm, and more preferably 3 μm to 20 μm.

The conductive polymer layer 16 disposed at least in the opening of the conductive mesh 14 has lower carrier (hole and electron) mobility than the metal conductive mesh 14. For this reason, a finer pitch of the conductive mesh 14 is advantageous in terms of device characteristics. However, the finer the pitch, the lower the light transmission, so a compromise is chosen. Although a pitch changes according to the line | wire width of a metal fine wire, it is preferable that they are 50 micrometers or more and 2000 micrometers or less, 100 micrometers or more and 1000 micrometers or less are more preferable, 150 micrometers or more and 500 micrometers or less are especially preferable. If another definition is used, it is preferable that the area of the opening 15 serving as a repeating unit of the conductive mesh 14 is 1 × 10 ⁻⁹ m ² or more and 1 × 10 ⁻⁵ m ² or less, and 3 × 10 ⁻⁹ m ^2. It is more preferably 1 × 10 ⁻⁶ m ² or less, and further preferably 1 × 10 ⁻⁸ m ² or more and 1 × 10 ⁻⁷ m ² or less.
The conductive mesh 14 may have a bus line (thick line) for large area current collection. The thickness and pitch of the bus line are appropriately selected according to the required light transmittance, conductivity, and the like.

  There is no restriction | limiting in particular as a formation method of the electroconductive mesh 14 in this invention, A well-known formation method can be used suitably. For example, a method in which a metal mesh prepared in advance is bonded to the substrate surface, a method in which a conductive material is applied in a pattern, a conductive film is formed on the entire surface by vapor deposition or sputtering, and then etched to form a mesh-shaped conductive film. A method of forming, a method of applying a conductive material in a pattern by various printing methods such as screen printing, ink jet printing, a method of directly forming a conductive mesh 14 in a pattern on a substrate surface using a mask vapor deposition method, etc. And a method using a silver halide light-sensitive material described in JP-A No. 2006-352073 and JP-A-2009-231194 (hereinafter sometimes referred to as a silver salt method).

The conductive mesh 14 of the present invention is preferably formed by a silver salt method because the pattern is fine. The conductive mesh produced by the silver salt method is a layer of silver and a hydrophilic polymer. Examples of hydrophilic polymers include water-soluble polymers such as gelatin, gelatin derivatives, casein, agar, sodium alginate, starch, and polyvinyl alcohol; cellulose esters such as carboxymethyl cellulose and hydroxyethyl cellulose. In addition to silver and hydrophilic polymer, the layer contains substances derived from the coating, developing and fixing processes.
When forming the conductive mesh 14 on the plastic film 12 by the silver salt method, a step of performing pattern exposure on the coating film for forming the conductive mesh 14, a step of developing the pattern-exposed coating film, and development Fixing the applied coating film.
Moreover, after forming a conductive mesh by a silver salt method, copper plating is performed, and the method of obtaining a conductive mesh with lower resistance is also preferably used.

(Conductive polymer layer)
In the present invention, the conductive polymer layer 16 needs to be transparent in the action spectrum range of the solar cell to be applied, and usually needs to be excellent in light transmittance from visible light to near infrared light. Specifically, the average light transmittance in the wavelength region of 400 nm to 800 nm when the film thickness is 0.2 μm is preferably 75% or more, and more preferably 85% or more.
The material for forming the conductive polymer layer 16 is not particularly limited as long as it is a polymer material having high conductivity. Specific examples of the conductive polymer include polythiophene, polypyrrole, polyaniline, polyphenylene vinylene, polyphenylene, polyacetylene, and a polymer having a plurality of these conductive skeletons.

Among these, polythiophene derivatives are preferable, polythiophene derivatives having a volume resistivity of 1 × 10 ⁻² Ωcm or less are more preferable, and polyethylene dioxythiophene is particularly preferable. These polythiophenes are usually partially oxidized in order to obtain conductivity. The conductivity of the conductive polymer can be adjusted by the degree of partial oxidation (doping amount), and the higher the doping amount, the higher the conductivity. Since polythiophene becomes cationic by partial oxidation, it has a counter anion to neutralize the charge. An example of such a polythiophene is polyethylene dioxythiophene (PEDOT-PSS) having polystyrene sulfonic acid as a counter ion.

  Other polymers may be added to the conductive polymer layer 16 as long as the desired conductivity is not impaired. Other polymers are added for the purpose of improving coatability and increasing the film strength. Examples of other polymers include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, transparent fluororesin, polyimide, fluorinated polyimide resin, polyamide resin, polyamideimide resin, polyetherimide resin, cellulose Acylate resin, polyurethane resin, polyether ether ketone resin, polycarbonate resin, alicyclic polyolefin resin, polyarylate resin, polyether sulfone resin, polysulfone resin, cycloolefin copolymer, fluorene ring modified polycarbonate resin, alicyclic modified polycarbonate resin , Fluorene ring-modified polyester resins, acryloyl compounds and other thermoplastic resins, gelatin, polyvinyl alcohol, polyacrylic acid, polyacrylamide, Pyrrolidone, polyvinyl pyridine, a hydrophilic polymer polyvinyl imidazole, and the like. These polymers may be cross-linked to increase the film strength.

The conductive polymer layer 16 in the present invention preferably contains a conductive polymer having a volume resistivity of 1 × 10 ⁻¹ Ωcm or less, and preferably contains a conductive polymer of 1 × 10 ⁻² Ωcm or less. More preferred.
With such containing a conductive polymer, preferably made with 5 × 10 ^-1 Ωcm or less as the volume resistivity of the conductive polymer layer 16, and more preferably a 5 × 10 ^-2 Ωcm or less.
The film thickness of the conductive polymer layer 16 is preferably in the range of 50 nm to 5 μm, and more preferably 100 nm to 2 μm.

  In many cases, the conductive polymer for forming the conductive polymer layer 16 is an aqueous solution or an aqueous dispersion. Therefore, a normal aqueous coating method is used for forming the conductive polymer layer. When the conductive mesh is produced by a silver salt method, a hydrophilic polymer is present around the conductive mesh, which is convenient for applying an aqueous dispersion. Various solvents, surfactants, thickeners and the like may be added to the conductive polymer coating solution as coating aids.

<Electronic block layer>
The organic solar cell of the present invention has an electron blocking layer 20 between the first transparent electrode (positive electrode) 18 and the bulk hetero layer 22. The electron blocking layer 20 has a function of blocking electrons from moving from the bulk hetero layer 22 to the positive electrode 18. The material having such a function includes an inorganic semiconductor called a p-type semiconductor and an organic compound called a hole transport material. More specifically, a metal oxide having a valence band level of 5.5 eV or less and a conductor level of 3.3 eV or less, or a HOMO level of 5.5 eV or less and a LUMO level. An organic compound whose position is 3.3 eV or less is exemplified. Specific examples of the metal oxide that can be used for the electron blocking layer 20 include molybdenum oxide and vanadium oxide. Specific examples of the organic compound that can be used for the electron blocking layer include aromatic amine derivatives, thiophene derivatives, condensed aromatic ring compounds, carbazole derivatives, polyaniline, polythiophene, and polypyrrole. In addition, Chem. Rev. A group of compounds described as Hole Transport material in 2007, 107, 953-1010 is also applicable.

Of these, polythiophene is preferable, and polyethylenedioxythiophene is more preferable. The polyethylene dioxythiophene is particularly preferably doped (partially oxidized) to such an extent that the volume resistivity does not fall below 10 Ωcm. At this time, you may have the counter anion derived from perchloric acid, polystyrene sulfonic acid, etc. for charge neutralization.
The film thickness of the electron block layer 20 is preferably 0.1 to 50 nm, more preferably 1 to 20 nm.

<Bulk hetero layer>
The bulk heterojunction photoelectric conversion layer (bulk hetero layer) 22 is an organic photoelectric conversion layer in which a hole transport material and an electron transport material are mixed. The mixing ratio of the hole transport material and the electron transport material is adjusted so that the conversion efficiency is the highest. Usually, the mass ratio is selected from the range of 10:90 to 90:10, but it is preferable to contain 50% by mass or more of the electron transport material. As a method for forming such a mixed organic layer, for example, a co-evaporation method by vacuum deposition is used. Or it is also possible to produce by carrying out solvent application | coating using the solvent in which both organic materials melt | dissolve. Specific examples of the solvent coating method will be described later.
The thickness of the bulk hetero layer 22 is preferably 10 to 500 nm, particularly preferably 20 to 300 nm.

  The hole transport material is a π-electron conjugated compound having a HOMO level of 4.5 to 6.0 eV, specifically, various arenes (for example, thiophene, carbazole, fluorene, silafluorene, thienopyrazine, thienobenzothiophene). , Dithienosilol, quinoxaline, benzothiadiazole, thienothiophene, etc.) coupled polymers, phenylene vinylene polymers, porphyrins, phthalocyanines, and the like. In addition, Chem. Rev. The compound group described as Hole Transport material in 2007, 107, 953-1010, and the porphyrin derivative described in Journal of the American Chemical Society Vol. 131, page 16048 (2009) are also applicable.

  Among these, a conjugated polymer obtained by coupling a structural unit selected from the group consisting of thiophene, carbazole, fluorene, silafluorene, thienopyrazine, thienobenzothiophene, dithienosilole, quinoxaline, benzothiadiazole, and thienothiophene is particularly preferable. Specific examples include poly-3-hexylthiophene, poly-3-octylthiophene, various polythiophene derivatives described in Journal of the American Chemical Society, Vol. 130, p. 3020 (2008), Advanced Materials, Vol. 19, p. 2295 (2007). PCDTBT, Journal of the American Chemical Society, vol. 130, page 732 (2008), PCDTQx, PCDTPP, PCDTPT, PCDTBX, PCDTPX, Nature Photonics, vol. 3, page 649 (2009) PBDTT-E, PBDTTTT-C, PBDTTTT-CF, Advanced Materials Vol. 22, E135-E138 (2010), PTB7, Special Table 2009-533 78 No. 35, pp paragraph [0092] compounds described in the publication, and the like.

The electron transport material is a π-electron conjugated compound having a LUMO level of 3.5 to 4.5 eV. Specifically, fullerene and its derivatives, phenylene vinylene-based polymers, naphthalene tetracarboxylic imide derivatives, perylene tetra Examples thereof include carboxylic acid imide derivatives. Of these, fullerene derivatives are preferred. Specific examples of fullerene derivatives include C ₆₀ , phenyl-C ₆₁ -methyl butyrate (fullerene derivatives referred to as PCBM, [60] PCBM, or PC ₆₁ BM in the literature), C ₇₀ , phenyl-C ₇₁ -methyl butyrate. (Fullerene derivatives referred to as PCBM, [70] PCBM, or PC ₇₁ BM in many literatures), and fullerene derivatives described in Advanced Functional Materials, Vol. 19, pp. 779-788 (2009), journals Examples include Fullerene Derivatives SIMEF described in OB American Chemical Society Vol. 131, page 16048 (2009).

<Electron transport layer>
In the present invention, an electron transport layer (not shown) made of an electron transport material may be provided between the bulk hetero layer 22 and the first transparent inorganic oxide layer 24 as necessary. Examples of the electron transport material that can be used for the electron transport layer include those described above and Chem. Rev. 2007, Vol. 107, pages 953-1010, which are described as Electron Transport Materials.
When providing an electron carrying layer, the thickness of an electron carrying layer is 1 nm-30 nm, Preferably it is 2 nm-15 nm.
The electron transport layer can be suitably formed by any of various wet film forming methods, dry film forming methods such as vapor deposition and sputtering, transfer methods, and printing methods.

<First transparent inorganic oxide layer>
A first transparent inorganic oxide layer 24 is provided between the bulk hetero layer 22 and the second transparent electrode 26. The transparent inorganic oxide constituting the first transparent inorganic oxide layer 24 is an n-type inorganic oxide semiconductor that is transparent and has an electron transporting property. Specifically, titanium oxide, zinc oxide, tin oxide, tungsten oxide, etc. Are exemplified, and titanium oxide and zinc oxide are preferable. These materials may be crystalline or amorphous.

If the film thickness of the first transparent inorganic oxide layer 24 is too thick, it prevents the passage of electrons. If the film thickness is too thin, the bulk hetero layer is formed when the second transparent inorganic oxide layer 26 is formed thereon. There is a possibility that the function of protecting 22 may be reduced. From such a viewpoint, the thickness of the first transparent inorganic oxide layer 24 is preferably 1 nm to 30 nm, and more preferably 2 nm to 15 nm.
The first transparent inorganic oxide layer 24 is formed by a method in which damage to the bulk hetero layer 22 is suppressed according to the constituent materials of the first transparent inorganic oxide layer 24 and the bulk hetero layer 22. For example, any wet film forming method, dry film forming method such as vapor deposition method or sputtering method, transfer method, printing method, etc. However, from the viewpoint of suppressing damage to the bulk hetero layer, a wet film forming method is preferable. In particular, the method of forming a zinc oxide layer described in Journal of Physical Chemistry Vol. 114, pages 6849 to 6853 (2010), Thin Solid Film Vol. 517, pages 3766 to 3769 (2007), Advanced Materials The method for forming a titanium oxide layer described in Volume 19, pages 2445 to 2449 (2007) is particularly suitable.

Specifically, for example, 10 ml of tetraisopropyl orthotitanate, 50 ml of 2-methoxyethanol, and 5 ml of ethanolamine are mixed, heated and stirred at 80 ° C. for 2 hours, and then heated and stirred at 120 ° C. for 1 hour. Further, heating and stirring at 80 ° C. for 2 hours and heating and stirring at 120 ° C. for 1 hour are repeated once more. This liquid is diluted 10 times with isopropyl alcohol to obtain a coating liquid for forming a transparent inorganic oxide layer.
The coating solution is spin-coated on the bulk hetero layer 22. At this time, the rotational speed of the spin coater is 4000 rpm. By heating this coating film at 150 ° C. for 25 minutes, an amorphous titanium oxide layer having a thickness of 20 nm can be obtained.

<Second transparent inorganic oxide layer>
On the 1st transparent inorganic oxide layer 24, the 2nd transparent inorganic oxide layer 26 which improved electroconductivity by impurity doping as the 2nd transparent electrode is provided. The transparent inorganic oxide constituting the second transparent inorganic oxide layer 26 is an n-type inorganic oxide semiconductor that is transparent and has an electron transporting property, and specifically includes titanium oxide, zinc oxide, tin oxide, and tungsten oxide. It is preferable to use titanium oxide or zinc oxide as the main component (the component having the highest ratio among the components constituting the second transparent inorganic oxide layer 26). In addition, the transparent inorganic oxide which comprises the 2nd transparent inorganic oxide layer 26 may be the same kind as the transparent inorganic oxide which comprises the 1st transparent inorganic oxide layer 24, and a different kind may be sufficient as it.

Impurity doping is performed for the purpose of improving conductivity by increasing the carrier density in the oxide layer 26. The element to be doped is a metal element in the right group in the periodic table with respect to the metal element of the inorganic oxide or a halogen element. For example, titanium oxide is doped with niobium and tantalum, which are group 5 elements, or with halogen (fluorine, chlorine, etc.). Zinc oxide is doped with a group 13 element such as boron, aluminum, gallium, or indium, or with halogen. In the case of tin oxide, it is usually doped with fluorine.
If the concentration of the dopant in the second transparent inorganic oxide layer 26 is too low, the function as an electrode becomes insufficient, and if it is too high, the light transmittance may be lowered. From these viewpoints, the dopant concentration in the second transparent inorganic oxide layer 26 is preferably 0.5 to 5% by mass, and more preferably 1 to 3% by mass.
The material constituting the second transparent inorganic oxide layer 26 may be crystalline or amorphous.

The film thickness of the second transparent inorganic oxide layer 26 serving as the second transparent electrode is preferably 10 nm to 500 nm, more preferably 50 nm to 400 nm, from the viewpoint of conductivity and light transmittance as the negative electrode. . The visible light (wavelength 400 nm to 800 nm) transmittance of the second transparent inorganic oxide layer 26 is preferably 50% or more, and more preferably 75% or more.
The second oxide semiconductor layer 26 can be formed by any of various types of wet film formation methods, dry film formation methods such as vapor deposition and sputtering, transfer methods, and printing methods. Of these, vapor deposition or sputtering is preferred. In the present invention, since the first transparent inorganic oxide layer 24 is provided on the bulk hetero layer 22, the second transparent inorganic oxide layer 26 is formed by a dry film forming method such as a vapor deposition method or a sputtering method. Even if the film is formed, damage to the bulk hetero layer 22 can be effectively suppressed. The first transparent inorganic oxide layer 24 and the second transparent inorganic oxide layer 26 serving as the second transparent electrode may be continuously formed. In this case, components other than the dopants of the first transparent inorganic oxide layer 24 and the second transparent inorganic oxide layer 26 are made of the same material, and the first transparent inorganic oxide layer 24 is formed as non-doped at the initial stage of film formation. A method of forming the second transparent inorganic oxide layer 26 by mixing a dopant in the middle of the film formation may be employed. The concentration of the dopant in the thickness direction of the second transparent inorganic oxide layer 26 may be constant or may be continuously increased.

The patterning for forming the second transparent inorganic oxide layer (second transparent electrode) 26 may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser, Vacuum deposition, sputtering, or the like may be performed with the masks overlapped.
In the present invention, the formation position of the second transparent inorganic oxide layer 26 is not particularly limited, and may be formed on the bulk hetero layer 22 via the first transparent inorganic oxide layer 24. You may form in the part. Even if a bus line 28 described later is provided on the second transparent inorganic oxide layer 26 or between the first transparent inorganic oxide layer 24 and the second transparent inorganic oxide layer 26. good.

<Bus line>
The 2nd transparent electrode may have the bus line (auxiliary wiring) 28 for improving electroconductivity, and is preferable. The bus line 28 is composed of a metal line that is in electrical contact with the second transparent inorganic oxide layer 26. The bus line 28 is designed so that the sheet resistance of the second transparent electrode is lowered over the entire surface of the organic solar cell. The shape of the bus line 28 may be a mesh having a uniform line width and pitch, a mesh having different line widths and pitches, or a so-called fishbone pattern in which a low-frequency thick line and a high-frequency thin line intersect, Other patterns may be used.
The film thickness of the bus line 28 is preferably 50 nm to 500 nm, and more preferably 80 nm to 300 nm. Further, the aperture ratio of the bus line is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more from the viewpoint of light transmittance.
The method for forming the bus line 28 is not particularly limited, but a vapor deposition method, a coating method, a printing method, a transfer method, or the like is preferably used.

<Recombination layer>
In a tandem element having two photoelectric conversion layers, a recombination layer is provided between the two photoelectric conversion layers. The material of the recombination layer is selected from the negative electrode materials. The film thickness of the recombination layer is 0.01 to 5 nm, preferably 0.1 to 1 nm, and particularly preferably 0.2 to 0.6 nm. There is no restriction | limiting in particular about the formation method of a recombination layer, For example, it can form by a vacuum evaporation method, sputtering method, an ion plating method, etc.

<Other organic layers>
In this invention, you may have auxiliary layers, such as a hole block layer and an exciton diffusion prevention layer, as needed. In the present invention, the term “organic layer” is used as a general term for layers using organic compounds such as a bulk hetero layer, a hole transport layer, an electron transport layer, an electron block layer, a hole block layer, and an exciton diffusion prevention layer.

<Annealing>
The organic thin film solar cell 10 of the present invention may be annealed by various methods for the purpose of crystallization of the organic layer and promotion of phase separation of the bulk hetero layer. Examples of the annealing method include a method of heating the temperature of the film substrate during vapor deposition to 50 ° C. to 150 ° C. and a method of setting the drying temperature after coating to 50 ° C. to 150 ° C. Further, after the formation of the second transparent electrode is completed, annealing may be performed by heating to 50 ° C. to 150 ° C.

<Protective layer>
The organic thin film solar cell of the present invention may be protected by a protective layer (not shown). In particular, it is preferable to form a protective layer on the negative electrode or on the negative electrode provided with a bus line from the viewpoint of preventing corrosion of the negative electrode.
The protective layer is preferably composed of an inorganic oxide or an inorganic nitride as a main component (a component having the highest ratio among the components constituting the protective layer). The material contained in the protective _{layer, MgO, SiO, SiO 2,} Al 2 O 3, Y 2 O 3, TiO metal oxides such as _2, metal nitrides such as SiN _x, metal nitrides such as _SiN x _{O y oxide, MgF 2, LiF, AlF 3} , CaF 2 , etc. of the metal fluoride, polyethylene, polypropylene, polyvinylidene fluoride, polymers such polyparaxylylene and the like. Of these, metal oxides, nitrides, and nitride oxides are preferable, and silicon, aluminum oxides, nitrides, and nitride oxides are particularly preferable. The protective layer may be a single layer or a multilayer structure.

  The method for forming the protective layer is not particularly limited, and for example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, vacuum ultraviolet CVD method, coating method, printing method, transfer method can be applied.

<Gas barrier layer>
The organic thin film solar cell 10 of the present invention may have a gas barrier layer (not shown). The gas barrier layer is not particularly limited as long as it has a gas barrier property. Usually, the gas barrier layer is an inorganic layer. Typically, the inorganic substance includes boron, magnesium, aluminum, silicon, titanium, zinc, tin oxide, nitride, oxynitride, carbide, hydride, and the like. These may be pure substances, or may be a mixture of multiple compositions or a gradient material layer. Of these, aluminum oxide, nitride or oxynitride, or silicon oxide, nitride or oxynitride is preferable.

The inorganic layer constituting the gas barrier layer may be a single layer or a laminate of a plurality of layers. The gas barrier layer may be a laminate of an organic layer and an inorganic layer, or may be an alternate laminate of a plurality of inorganic layers and a plurality of organic layers. The organic layer is not particularly limited as long as it is a smooth layer, but a layer made of a polymer of (meth) acrylate is preferably exemplified. The thickness of the gas barrier layer is not particularly limited, but it is usually attached to one layer, It exists in the range of 5-500 nm, Preferably it is 10-200 nm. The gas barrier layer may have a laminated structure including a plurality of sublayers. In this case, each sublayer may have the same composition or a different composition. Moreover, as described in US Patent Application Publication No. 2004/46497, a layer in which the interface with the organic polymer layer is not clear and the composition continuously changes in the film thickness direction may be used.

  From the viewpoint of flexibility, the thickness of the organic thin film solar cell 10 of the present invention is preferably 50 μm to 1 mm, and more preferably 100 μm to 500 μm.

  In addition, when producing a solar cell module using the organic thin film solar cell 10 of the present invention, it is possible to take into account the descriptions of Yasuhiro Tsujikawa, photovoltaic power generation, the latest technology and system (publishing: CMC Co., Ltd.) it can.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[Example 1]
On a polyethylene naphthalate film having a thickness of 125 μm (a film commercially available under the name of Teonex Q-65FA from Teijin DuPont Co., Ltd.), a conductive mesh, a conductive polymer layer, an electronic block layer, a bulk hetero layer, a transparent oxide layer, A negative electrode, a bus line, and a protective layer were laminated in this order to produce a bulk hetero type organic thin film solar cell of the present invention.

[Formation of conductive mesh]
[Preparation of silver halide emulsion]
The following solution A was kept at 34 ° C. in a reaction vessel, and the pH was adjusted to 2.95 using nitric acid (concentration 6%) while stirring at high speed using a mixing and stirring device described in JP-A-62-2160128. It was adjusted. Subsequently, the following solution B and the following solution C were added at a constant flow rate over 8 minutes and 6 seconds using the double jet method. After completion of the addition, the pH was adjusted to 5.90 using sodium carbonate (concentration 5%), and then the following solution D and solution E were added.

(Solution A)
Alkali-treated inert gelatin (average molecular weight 100,000) 18.7g
Sodium chloride 0.31g
Solution I (below) 1.59 mL
Pure water 1,246mL

(Solution B)
169.9g of silver nitrate
Nitric acid (concentration 6%) 5.89 mL
The total volume was adjusted to 317.1 mL with pure water.

(Solution C)
Alkali-treated inert gelatin (average molecular weight 100,000) 5.66 g
Sodium chloride 58.8g
13.3 g of potassium bromide
Solution I (below) 0.85mL
Solution II (below) 2.72 mL
The total volume was adjusted to 317.1 mL with pure water.

(Solution D)
2-Methyl-4hydroxy-1,3,3a, 7-tetraazaindene 0.56 g
Pure water 112.1mL

(Solution E)
Alkali-treated inert gelatin (average molecular weight 100,000) 3.96 g
Solution I (below) 0.40mL
128.5 mL of pure water

<Solution I>
Surfactant: 10% by mass methanol solution of polyisopropylene polyethylene oxydisuccinate sodium salt

<Solution II>
10% by weight aqueous solution of rhodium hexachloride complex

  After completion of the above operation, desalting and washing with water using a flocculation method are performed at 40 ° C. according to a conventional method, and the solution F and an anti-bacterial agent are added and dispersed well at 60 ° C. .90 adjusted. Finally, a silver chlorobromide cubic grain emulsion containing 10 mol% of silver bromide and having an average grain size of 0.09 μm and a coefficient of variation of 10% was obtained.

(Solution F)
Alkali-treated inert gelatin (average molecular weight 100,000) 16.5g
Pure water 139.8mL

  The silver chlorobromide cubic grain emulsion was subjected to chemical sensitization at 40 ° C. for 80 minutes using 20 mg of sodium thiosulfate per mole of silver halide, and after completion of chemical sensitization, 4-hydroxy-6-methyl-1 , 3,3a, 7-tetrazaindene (TAI) was added in an amount of 500 mg per mole of silver halide and 1-phenyl-5-mercaptotetrazole was added in an amount of 150 mg per mole of silver halide to obtain a silver halide emulsion. This silver halide emulsion had a volume ratio of silver halide grains to gelatin (silver halide grains / gelatin) of 0.625.

  Further, a hardening agent (H-1: tetrakis (vinylsulfonylmethyl) methane) was added at a ratio of 200 mg per 1 g of gelatin, and a surfactant (SU-2: sulfosuccinate disulfate) was applied as a coating aid. (2-ethylhexyl) .sodium) was added to adjust the surface tension.

[Application]
The thus obtained coating solution is a polyethylene nab having a thickness of 100 μm and a visible light transmittance of 92% (anti-reflective treatment on the back surface) with an undercoat layer so that the basis weight in terms of silver is 0.625 g / m ^2. After coating on a phthalate (PEN) film substrate, a curing process was performed at 50 ° C. for 24 hours to obtain a photosensitive material.

[exposure]
The obtained photosensitive material was exposed with a UV exposure device through a mesh photomask (line width: 5 μm, pitch: 300 μm).

[Chemical development]
The exposed photosensitive material is subjected to development processing at 25 ° C. for 60 seconds using the following developer (DEV-1), and then subjected to fixing processing at 25 ° C. for 120 seconds using the following fixing solution (FIX-1). went.

(DEV-1)
500 mL of pure water
Metol 2g
80 g of anhydrous sodium sulfite
Hydroquinone 4g
4g borax
Sodium thiosulfate 10g
Potassium bromide 0.5g
Water was added to make up a total volume of 1 liter.

(FIX-1)
750 mL of pure water
Sodium thiosulfate 250g
Anhydrous sodium sulfite 15g
Glacial acetic acid 15mL
Potash alum 15g
Water was added to make up a total volume of 1 liter.

[Physical development]
Next, physical development was performed at 30 ° C. for 10 minutes using the following physical developer (PDEV-1), and then washed with tap water for 10 minutes.

(PDEV-1)
900mL pure water
Citric acid 10g
Trisodium citrate 1g
Ammonia water (28%) 1.5g
Hydroquinone 2.3g
Silver nitrate 0.23g
Water was added to make a total volume of 1000 mL.

[Electrolytic plating]
After the physical development treatment, electrolytic copper plating treatment was performed at 25 ° C. using the following electrolytic plating solution, followed by washing with water and drying treatment. In addition, the current control in electrolytic copper plating was performed over 3 minutes, 3 minutes for 1 minute and then 12 minutes for 1A. After the completion of the plating treatment, the plate was rinsed with tap water for 10 minutes to carry out a water washing treatment, and dried using a dry air (50 ° C.) until it was in a dry state.

(Electrolytic plating solution)
Copper sulfate (pentahydrate) 200g
50g of sulfuric acid
Sodium chloride 0.1g
Water was added to make a total volume of 1000 mL.

  When the film after the plating treatment was observed with an electron microscope, it was confirmed that a metal mesh pattern having a line width of 14 μm and a pitch of 300 μm was formed on the film substrate. Thus, a transparent conductive film (A-0) was obtained.

[Measurement of surface resistance]
When the surface resistance of the transparent conductive film (A-0) was measured according to JIS 7194 using a Mitsubishi Chemical Corporation low resistivity meter Lorester GP / ASP probe, the surface resistance value was 1 Ω / sq or less.

[Formation of conductive polymer layer]
On the surface of the transparent conductive film (A-0), an aqueous dispersion of polyethylenedioxythiophene / polystyrenesulfonic acid (abbreviation: PEDOT-PSS) (manufactured by HC Starck Co., Ltd., 5% by mass of ethylene in Crevios PH-500) A solution to which glycol was added and a volume resistivity of 1 to 5 × 10 ⁻³ Ωcm at the time of coating and drying were applied. Next, this film was heat-dried at 120 ° C. for 20 minutes to form a conductive polymer layer to obtain a transparent conductive film. At this time, the film thickness of the conductive polymer layer was 300 nm.

[Formation of electron blocking layer]
An aqueous dispersion of polyethylenedioxythiophene / polystyrene sulfonic acid (abbreviation: PEDOT-PSS) (manufactured by HC Stark, Crevios P AI4083, volume resistivity 500 to 5000 Ωcm when applied and dried) on the transparent conductive film. It apply | coated so that it might become a film thickness of 25 nm, and it heat-dried at 120 degreeC for 20 minutes.

[Formation of bulk hetero layer]
P3HT (poly-3-hexylthiophene, Lisicon SP-001 (trade name), manufactured by Merck & Co., Inc.) 20 mg, and PCBM ([6,6] -phenyl C ₆₁ -butyl acid acid ester, Nanomu Spectra E-100H (product) Name), 14 mg (manufactured by Frontier Carbon Co., Ltd.) was dissolved in 1 ml of chlorobenzene to obtain a coating liquid for forming a bulk hetero layer. This coating solution was spin-coated on the electron block layer to form a bulk hetero layer. The rotation speed of the spin coater was 2000 rpm, and the dry film thickness was 90 nm.

(Formation of transparent inorganic oxide layer)
10 ml of tetraisopropyl orthotitanate, 50 ml of 2-methoxyethanol, and 5 ml of ethanolamine were mixed, heated and stirred at 80 ° C. for 2 hours, and then heated and stirred at 120 ° C. for 1 hour. Further, heating and stirring at 80 ° C. for 2 hours and heating and stirring at 120 ° C. for 1 hour were repeated once more. This liquid was diluted 10 times with isopropyl alcohol to obtain a coating liquid for forming a transparent inorganic oxide layer.
The coating solution was spin-coated on the bulk hetero layer. The rotation speed of the spin coater was 4000 rpm. By heating this coating film at 150 ° C. for 25 minutes, an amorphous titanium oxide layer having a thickness of 10 nm was obtained.

[Formation of negative electrode and bus line]
Using a sputtering method, ZnO-Al in which 2 wt% of aluminum was doped in ZnO was formed on the transparent inorganic oxide layer so as to have a film thickness described in Table 1. At this time, a mask having an effective area of 4 cm ² was used.
Subsequently, Ag was vapor-deposited twice using a stripe mask having a pitch of 2 mm and a line width of 100 μm to produce a square mesh bus line (film thickness: 200 nm). The stripe mask was rotated 90 ° in the first and second times so that the resulting bus line had a mesh pattern.

(Formation of protective layer)
Next, a silicon nitride layer was formed as a protective film on the negative electrode using a capacitively coupled plasma CVD apparatus. The organic thin film solar cell element in which the negative electrode and the bus line have been formed is set in a CVD reaction chamber, and under a reduced pressure, a raw material gas according to the raw material gas formulation described below is introduced, and a high frequency power of 13.56 MHz is introduced. Was applied to generate plasma to form a silicon nitride layer. The film formation time was adjusted so that the thickness was 2 μm.

(Raw gas prescription)
Silane 25 sccm, ammonia 15 sccm, hydrogen 15 sccm, nitrogen 195 sccm

  By the above method, the bulk hetero type organic thin film solar cell element (P-1) of the present invention was produced.

[Example 2]
On a PEN film with ITO having a surface resistance of 13 Ω / sq (a film sold under the product name PECF-IP from Pexel Technologies), an electron block layer, a bulk hetero layer, a transparent oxide layer, a negative electrode, a bus line, The protective layer was sequentially laminated in the same manner as in Example 1 to produce an organic thin film solar cell (P-2).

Example 3
An organic thin-film solar cell (P-3) was produced in the same manner as in Example 1 except that the film thickness of ZnO-Al as the negative electrode was 30 nm.

Example 4
An organic thin film solar cell (P-4) was produced in the same manner as in Example 1 except that the thickness of the amorphous titanium oxide layer, which was a transparent inorganic oxide, was 100 nm.

[Comparative Example 1]
A comparative solar cell (R-1) was produced in the same manner as in Example 1 except that Ag—Mg was deposited in a thickness of 15 nm instead of ZnO—Al as the negative electrode.

[Comparative Example 2]
A comparative solar cell (R-2) was produced in the same manner as in Example 1 except that the transparent inorganic oxide layer was not formed.

[Comparative Example 3]
An organic thin-film solar cell (R-3) was produced in the same manner as in Example 1 except that 300 nm of SnO ₂ was formed as the negative electrode.
Table 1 below shows the structures of the organic thin film solar cells prepared in Examples and Comparative Examples.

[Measurement of power generation efficiency]
The organic thin film solar cells obtained in the examples and comparative examples were irradiated with simulated sunlight of AM1.5G, 100 mW / cm ² using a Pexel Technologies L12 type solar simulator, and the source measure unit (SMU2400). The current value was measured in a voltage range of −0.1 V to 1.0 V using a mold (manufactured by KEITHLEY). The obtained current-voltage characteristics were evaluated using a Pexel Technologies IV curve analyzer, and characteristic parameters were calculated.

Next, after each element was left in a high-temperature and high-humidity chamber at 40 ° C. and 90% relative humidity for 100 hours, the current-voltage characteristics were measured while irradiating simulated sunlight at AM 1.5 and 100 mW / cm ^2. The maintenance ratio of conversion efficiency was measured by the formula.
Conversion efficiency maintenance rate (%) =
{(Conversion efficiency after aging at high temperature and high humidity) / (Conversion efficiency immediately after device fabrication)} × 100
The measurement results are shown in Table 2.

DESCRIPTION OF SYMBOLS 10 Organic thin film solar cell 12 Plastic film board | substrate 14 Conductive mesh 15 Opening part 16 Conductive polymer layer 18 1st transparent electrode (positive electrode)
20 electron blocking layer 22 bulk hetero layer 24 first transparent inorganic oxide layer 26 second transparent inorganic oxide layer 28 bus line

Claims (24)

  A first transparent electrode, an electron blocking layer, a bulk heterojunction photoelectric conversion layer, a first transparent inorganic oxide layer, and a doped second transparent inorganic oxide layer are included on a plastic film substrate. The organic thin-film solar cell which has a 2nd transparent electrode in this order.   The organic thin-film solar cell according to claim 1, wherein the second transparent inorganic oxide layer is mainly composed of titanium oxide or zinc oxide.   The organic thin-film solar cell according to claim 1 or 2, wherein a film thickness of the second transparent inorganic oxide layer is 50 nm to 400 nm.   The first transparent inorganic oxide layer according to any one of claims 1 to 3, wherein the first transparent inorganic oxide layer includes at least one inorganic oxide selected from the group consisting of titanium oxide, zinc oxide, and tin oxide. Organic thin film solar cell.   The organic thin-film solar cell according to any one of claims 1 to 4, wherein the first transparent inorganic oxide layer has a thickness of 1 nm to 30 nm.   The organic thin-film solar cell according to any one of claims 1 to 5, wherein the second transparent inorganic oxide layer has a visible light transmittance of 50% or more.   The organic thin-film solar cell of any one of Claims 1-6 which has a bus line on a said 2nd transparent electrode.   The organic thin-film solar cell of any one of Claims 1-7 which has a bus line between a said 1st transparent inorganic oxide layer and a 2nd transparent electrode.   The organic thin-film solar cell of any one of Claims 1-8 which has a protective layer on a said 2nd transparent electrode.   The organic thin-film solar cell according to claim 9, wherein the protective layer contains an inorganic oxide or an inorganic nitride as a main component.   The said 1st transparent electrode contains a conductive mesh and the conductive polymer layer which is arrange | positioned in at least opening part of this conductive mesh, and contact | connects this conductive mesh. Organic thin film solar cell.   The organic thin-film solar cell according to claim 11, wherein the conductive mesh contains silver.   The organic thin-film solar cell according to claim 11 or 12, wherein the conductive mesh contains silver and a hydrophilic polymer.   The organic thin-film solar cell according to any one of claims 11 to 13, wherein a line width in a plan view of the conductive mesh is 1 µm or more and 20 µm or less.   The organic thin-film solar cell according to any one of claims 11 to 14, wherein a pitch of the conductive mesh in a plan view is 50 µm or more and 500 µm or less. The organic thin-film solar cell according to any one of claims 11 to 15, wherein an area of an opening serving as a repeating unit in the conductive mesh is 1 × 10 ⁻⁸ m ² or more and 1 × 10 ⁻⁷ m ² or less. .   The organic thin-film solar cell according to any one of claims 11 to 16, wherein the conductive polymer layer contains a polythiophene derivative. The organic thin-film solar cell according to claim 17, wherein the volume resistivity of the polythiophene derivative is 1 × 10 ⁻² Ωcm or less.   The organic thin-film solar cell according to claim 17 or 18, wherein the polythiophene derivative is polyethylenedioxythiophene.   The organic thin film solar cell according to claim 1, wherein the bulk heterojunction photoelectric conversion layer contains a fullerene derivative.   The organic thin-film solar pond according to any one of claims 1 to 20, wherein the bulk heterojunction photoelectric conversion layer contains 50% by mass or more of an electron transport material.   Forming on the plastic film substrate a first transparent electrode including a conductive mesh and a conductive polymer layer disposed in at least an opening of the conductive mesh and in contact with the conductive mesh; and on the first transparent electrode And sequentially forming an electron blocking layer, a bulk heterojunction photoelectric conversion layer, a first transparent inorganic oxide layer, and a second transparent electrode containing a doped second transparent inorganic oxide And a method for producing an organic thin film solar cell.   The method for producing an organic thin-film solar cell according to claim 22, wherein the first transparent inorganic oxide layer is formed by a wet film formation method.   The conductive mesh on the plastic film substrate is subjected to pattern exposure on the coating film for forming the conductive mesh, the process of developing the pattern-exposed coating film, and the developed coating film The method for producing an organic thin-film solar cell according to claim 22 or 23, wherein the method comprises:

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