JP2014236064A - Method for manufacturing organic thin film solar cell and organic thin film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing an organic thin film solar cell which can suppress reduction in the power generation efficiency, with excellent productivity.SOLUTION: The method for manufacturing the organic thin film solar cell 100 comprises: at least of two steps of following steps (1) and (2); a step (1) is for preparing a laminated body 110 in which a transparent electrode layer 102 and an organic semiconductor layer 103 are laminated in the order on a transparent substrate 101; and a step (2) is for forming a back electrode layer 104 on the organic semiconductor layer 103 by spraying and applying fluid dispersion containing metal nano particles and disperse medium onto the organic semiconductor layer 103 as droplets and by drying and removing the disperse medium.

Description

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

In general, an organic thin film solar cell has a configuration in which a transparent electrode layer, an organic semiconductor layer, and a back electrode layer are laminated in this order on a transparent substrate.
Such an organic thin-film solar cell has advantages such as a simpler manufacturing method, lower production costs, and imparting colorability, flexibility, and the like as compared with an inorganic solar cell using silicon or an inorganic compound material.

  Examples of the method for forming a solar cell electrode include a vacuum process, a sputtering process, a PVD process such as an ion plating process, a dry process such as a CVD process, and a wet process that uses a dispersion containing metal nanoparticles. Etc. are known.

  In Patent Document 1 (Japanese Patent Laid-Open No. 2012-147014), a dispersion liquid in which metal nanoparticles are dispersed in a dispersion medium is applied onto a substrate by a wet coating method, and then the obtained film is baked to obtain a solar cell. A method of forming a working electrode is described.

  Since such a wet process can simplify the apparatus as compared with a dry process, it is excellent in productivity. Furthermore, there is an advantage that the area of the electrode can be easily increased.

JP 2012-147014 A International Publication No. 2011/114713 Pamphlet

  However, according to the study by the present inventors, it has been clarified that the organic thin-film solar cell obtained by the wet process has lower power generation efficiency than that obtained by the dry process.

  Therefore, the present invention provides a manufacturing method capable of manufacturing an organic thin film solar cell in which a decrease in power generation efficiency is suppressed with high productivity.

  The present inventors diligently studied the factors that cause a decrease in power generation efficiency. As a result, on the organic semiconductor layer, it was found that by forming a back electrode layer by spraying a dispersion containing metal nanoparticles as droplets, a reduction in power generation efficiency of the resulting organic thin film solar cell can be suppressed, The present invention has been reached.

That is, according to the present invention,
A method for producing an organic thin-film solar cell in which at least a transparent electrode layer, an organic semiconductor layer, and a back electrode layer are laminated in this order on a transparent substrate,
Preparing a laminate in which the transparent electrode layer and the organic semiconductor layer are laminated in this order on the transparent substrate;
Forming a back electrode layer on the organic semiconductor layer by spray-coating a dispersion liquid containing metal nanoparticles and a dispersion medium as droplets on the organic semiconductor layer and drying and removing the dispersion medium; ,
A method for producing an organic thin film solar cell is provided.

Furthermore, according to the present invention,
An organic thin film solar cell obtained by the method for producing an organic thin film solar cell of the present invention is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which can manufacture the organic thin film solar cell by which the fall of power generation efficiency was suppressed with sufficient productivity can be provided.

It is sectional drawing which shows an example of a structure of the organic thin film solar cell of embodiment which concerns on this invention. It is sectional drawing which shows the manufacturing process of the organic thin-film solar cell of embodiment which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate. The figure is a schematic view and does not necessarily match the actual dimensional ratio. In addition, unless otherwise specified, “to” represents the following.

<Method for producing organic thin-film solar cell>
Hereinafter, the manufacturing method of the organic thin film solar cell 100 which concerns on this embodiment is demonstrated.
FIG. 1 is a cross-sectional view illustrating an example of the configuration of an organic thin-film solar cell 100 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a manufacturing process of the organic thin-film solar cell 100 according to the embodiment of the present invention.

The manufacturing method of the organic thin film solar cell 100 of the present invention is an organic thin film solar cell 100 in which at least a transparent electrode layer 102, an organic semiconductor layer 103, and a back electrode layer 104 are laminated in this order on a transparent substrate 101 (FIG. The manufacturing method of 1) includes at least the following two steps (1) and (2).
(1) A step of preparing a laminate 110 in which a transparent electrode layer 102 and an organic semiconductor layer 103 are laminated in this order on a transparent substrate 101 (FIG. 2A).
(2) The back electrode layer 104 is formed on the organic semiconductor layer 103 by spray-coating the dispersion containing the metal nanoparticles and the dispersion medium as droplets on the organic semiconductor layer 103 and drying and removing the dispersion medium. Step (FIG. 2B)

  According to the method for manufacturing the organic thin film solar cell 100 of the present invention, the power generation efficiency of the obtained organic thin film solar cell 100 is obtained by spray-coating the dispersion containing the metal nanoparticles as droplets on the organic semiconductor layer 103. Reduction can be suppressed.

The reason why the decrease in power generation efficiency of the obtained organic thin-film solar cell 100 can be suppressed by using the method for producing the organic thin-film solar cell 100 of the present invention is not necessarily clear, but the present inventors speculate as follows. ing.
First, in the case of an organic thin film solar cell, an aqueous dispersion is usually used in the dispersion containing metal nanoparticles so as not to dissolve the organic semiconductor layer. Since the aqueous dispersion has a higher surface tension than the organic dispersion, it is easily repelled when applied on the organic semiconductor layer. Therefore, it is considered that thickness unevenness is easily generated in the obtained back electrode layer, or an unformed part of the back electrode layer is likely to occur.
When thickness unevenness or an unformed part occurs in the back electrode layer, a short circuit easily occurs between the transparent electrode layer and the back electrode layer, and as a result, the power generation efficiency of the organic thin-film solar cell decreases.
Therefore, the organic thin-film solar cell obtained by the wet process is considered to have lower power generation efficiency than that obtained by the dry process.
On the other hand, according to the study by the present inventors, the method of spray-coating a dispersion containing metal nanoparticles on the organic semiconductor layer 103 as droplets can suppress the repelling of the dispersion on the organic semiconductor layer 103, As compared with other wet processes, it has been found that unevenness in thickness and unformed portions of the back electrode layer 104 can be suppressed.
From the above, when the method for manufacturing the organic thin film solar cell 100 of the present invention is used, unevenness in the thickness of the back electrode layer 104 and generation of unformed parts can be suppressed, so that the gap occurs between the transparent electrode layer 102 and the back electrode layer 104. It is thought that a short circuit can be suppressed and, as a result, a decrease in power generation efficiency of the obtained organic thin film solar cell 100 can be suppressed.

Moreover, in the manufacturing method of the organic thin film solar cell 100 which concerns on this embodiment, from a viewpoint which can suppress further the fall of the power generation efficiency of the organic thin film solar cell 100 obtained, as a protective agent which disperse | distributes a metal nanoparticle, organic (pi) junction It is preferable to use a ligand. The reason why the decrease in power generation efficiency of the obtained organic thin-film solar cell 100 can be further suppressed by using the organic π-junction ligand is not necessarily clear, but the present inventors presume as follows.
In the prior art, in order to disperse the metal nanoparticles in the dispersion medium so as not to aggregate, the surface of the metal nanoparticles is protected with organic molecules. Furthermore, after the metal nanoparticles dispersed in the dispersion medium were applied on the organic semiconductor layer, the film was baked at about 150 ° C. This is because the electrical conductivity of the back electrode layer formed after coating is not improved unless a firing step is obtained. By passing through this firing step, the organic molecules in the protective agent that protected the surface of the metal nanoparticles were desorbed or decomposed, or desorbed and decomposed, so that the metal substantially free of organic matter was removed. A back electrode layer containing the main component could be obtained.
The organic power generation material of the organic thin film solar cell may be annealed at a high temperature. However, if heat treatment is applied more than necessary, the characteristics of the obtained organic thin film solar cell will deteriorate. Therefore, in the said baking process, since heat processing is performed so that an organic molecule is desorbed or decomposed | disassembled, it is estimated that the conventional organic thin film solar cell will reduce electric power generation efficiency.
On the other hand, according to the study by the present inventors, by using an organic π-junction ligand as a protective agent for metal nanoparticles, it is only necessary to dry the solvent without obtaining the above baking step. It has been found that a back electrode layer having high electrical conductivity can be formed. Thereby, it is not necessary to anneal the organic power generation material at a higher temperature than necessary, and a solar cell element can be manufactured. As a result, it is considered that a decrease in power generation efficiency of the obtained solar cell can be suppressed.
In the present embodiment, a baking step at 100 ° C. or higher may be performed before the back electrode layer is formed. In this case, the heating time is preferably less than 10 minutes, preferably less than 6 minutes, and it is preferably performed in an inert atmosphere such as nitrogen gas.

  Hereinafter, each step will be described in detail.

  First, the process (FIG. 2 (a)) which prepares the laminated body 110 is demonstrated. The stacked body 110 can be obtained, for example, by sequentially forming the transparent electrode layer 102 and the organic semiconductor layer 103 on the transparent substrate 101. Moreover, you may prepare what laminated | stacked the transparent electrode layer 102 and the organic-semiconductor layer 103 in this order on the transparent substrate 101 already.

  First, the transparent electrode layer 102 is formed on the entire surface of the transparent substrate 101 or in a predetermined pattern shape. As a method for forming the transparent electrode layer 102, a general electrode forming method can be used. For example, a dry process such as a PVD method such as a vacuum deposition method, a sputtering method, or an ion plating method, a CVD method, a wet process for applying a coating liquid, or the like can be given.

The transparent substrate 101 is not particularly limited as long as it is a substrate transparent to visible light, and a substrate generally used for an organic thin film solar cell can be used. For example, a glass substrate, a plastic film substrate, etc. are mentioned.
The thickness of the transparent substrate 101 is not particularly limited, but is usually in the range of 10 μm to 200 μm.

The transparent electrode layer 102 is provided on the transparent substrate 101 and is an electrode facing the back electrode layer 104. The transparent electrode layer 102 is not particularly limited as long as it is transparent to visible light and has electrical conductivity, and those generally used for organic thin-film solar cells can be used. Examples thereof include those formed of transparent conductive oxides such as tin-added indium oxide (ITO), tin oxide (SnO ₂ ), fluorine-doped tin oxide (FTO), and antimony-doped tin oxide (ATO).
The thickness of the transparent electrode layer 102 is not particularly limited, but is usually in the range of 5 nm to 100 μm.

  Next, the organic semiconductor layer 103 is formed on the transparent electrode layer 102.

The organic semiconductor layer 103 is formed between the transparent electrode layer 102 and the back electrode layer 104, contributes to charge separation of the organic thin film solar cell 100, and generates generated electrons and holes in opposite directions. It has the function of transporting towards.
The organic semiconductor layer 103 may be a single layer having both an electron accepting function and an electron donating function, or an electron accepting layer having an electron accepting function and an electron donating function having an electron donating function. It may be a laminate of a conductive layer.
In the present embodiment, the organic semiconductor layer 103 is preferably a laminate of an electron accepting layer and an electron donating layer. With such a configuration, the power generation efficiency of the obtained organic thin film solar cell 100 can be further improved.

The electron donating material (also referred to as a p-type organic semiconductor material) is not particularly limited as long as it has an electron donating function, and those generally used for organic thin film solar cells are used. be able to. For example, an electron-donating conductive polymer material can be given.
Examples of the electron-donating conductive polymer material include polyphenylene, polyphenylene vinylene, polysilane, polythiophene, polycarbazole, polyvinyl carbazole, porphyrin, polyacetylene, polypyrrole, polyaniline, polyfluorene, polyvinyl pyrene, polyvinyl anthracene, and derivatives thereof. , Phthalocyanine-containing polymer, carbazole-containing polymer, organometallic polymer, and the like.

  The electron-accepting material (also referred to as an n-type organic semiconductor material) is not particularly limited as long as it has an electron-accepting function, and is generally used for organic thin-film solar cells. Can be used. For example, fullerene derivatives, carbon nanotubes, perylene derivatives and the like can be mentioned.

  As the film thickness of the organic semiconductor layer 103, a film thickness generally employed in an organic thin film solar cell can be employed. For example, it is in the range of 0.2 nm to 3000 nm. When the film thickness is within the above range, the balance between conductivity and light absorption of the organic semiconductor layer 103 is excellent. Moreover, it can suppress further that a short circuit arises between the transparent electrode layer 102 and the back surface electrode layer 104 as a film thickness is more than the said lower limit.

  The mixing ratio of the electron-donating material and the electron-accepting material is appropriately adjusted to an optimal mixing ratio depending on the type of material used.

  When the organic semiconductor layer 103 is a laminate of an electron-accepting layer and an electron-donating layer, the thickness of the electron-accepting layer is, for example, in the range of 0.1 nm to 1500 nm, The film thickness of the donor layer is, for example, in the range of 0.1 nm to 1500 nm. When the film thickness is within the above range, the balance between conductivity and light absorption of the organic semiconductor layer 103 is excellent. Moreover, it can suppress further that a short circuit arises between the transparent electrode layer 102 and the back surface electrode layer 104 as a film thickness is more than the said lower limit.

The organic semiconductor layer 103 may be provided with an organic hole transport layer (also referred to as a hole extraction layer) on the transparent electrode layer 102 side.
The organic hole transport layer is a layer provided so that holes can be easily taken out from the organic semiconductor layer 103 to the transparent electrode layer 102. Thereby, since the hole extraction efficiency from the organic semiconductor layer 103 to the transparent electrode layer 102 is increased, the power generation efficiency of the obtained organic thin film solar cell 100 can be further improved.

The material used for the organic hole transport layer is not particularly limited as long as it is a material that stabilizes the extraction of holes from the organic semiconductor layer 103 to the transparent electrode layer 102, and is generally an organic thin film solar cell. What is used for can be used. Examples thereof include conductive organic compounds such as doped polyethylene dioxythiophene (PEDOT) and tetraphenylphenylenediamine (TPD), and oxides such as vanadium oxide and molybdenum oxide.
Here, examples of the dopant doped into the conductive organic compound include polystyrene sulfonic acid (PSS).
As a combination of such a conductive organic compound and a dopant, a combination (PEDOT / PSS) of polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) is particularly preferable.

  As the film thickness of the organic hole transport layer, a film thickness generally employed in organic thin film solar cells can be employed. For example, it is in the range of 10 nm to 200 nm.

The organic semiconductor layer 103 may be provided with an organic electron transport layer (also referred to as an electron extraction layer) on the back electrode layer 104 side.
The organic electron transport layer is a layer provided so that electrons can be easily extracted from the organic semiconductor layer 103 to the back electrode layer 104. Thereby, since the electron extraction efficiency from the organic semiconductor layer 103 to the back electrode layer 104 is increased, the power generation efficiency of the obtained organic thin-film solar cell 100 can be further improved.

  The material used for the organic electron transport layer is not particularly limited as long as it is a material that stabilizes the extraction of electrons from the organic semiconductor layer 103 to the back electrode layer 104, and is used for an organic thin film solar cell. Generally known ones can be used. Examples thereof include alkali metals such as calcium and cesium, metal fluorides such as lithium fluoride and calcium fluoride, and oxides such as titanium oxide and zinc oxide.

  Further, an organic hole transport layer may be provided on the back electrode layer 104 side, and an organic electron transport layer may be provided on the transparent electrode layer 102 side. By setting it as such a structure, it can be set as an organic thin film solar cell of what is called a reverse structure.

  The method for forming the organic semiconductor layer 103 is not particularly limited as long as it can be uniformly formed to have a predetermined film thickness, and examples thereof include a wet coating method. When the wet coating method is used, the organic semiconductor layer 103 can be formed in the air, so that cost can be reduced and the area can be easily increased.

  The single organic semiconductor layer 103 having both the electron accepting and electron donating functions can be obtained, for example, by applying a coating liquid containing the above-described electron donating material, electron accepting material, and organic solvent on the transparent electrode layer 102. The organic solvent can be formed by coating and then drying to remove the organic solvent.

  On the other hand, the organic semiconductor layer 103 in which the electron-accepting layer and the electron-donating layer are stacked can be formed by, for example, the following method. First, the coating liquid containing the electron donating material and the organic solvent described above is applied onto the transparent electrode layer 102 to form a coating film, and then the organic solvent is dried and removed to make the electron donating layer transparent. It is formed on the electrode layer 102. Next, the above-described coating solution containing the electron-accepting material and the organic solvent is applied onto the electron-donating layer to form a coating film, and then the organic solvent is removed by drying to remove the electron-accepting layer. Form on the donor layer. By doing so, the organic semiconductor layer 103 in which the electron-accepting layer and the electron-donating layer are stacked can be formed on the transparent electrode layer 102.

  In addition, the organic hole transport layer and the organic electron transport layer can be formed according to the formation method of the electron accepting layer and the electron donating layer, respectively.

  The application method of the coating liquid is not particularly limited as long as it is a method capable of uniformly applying the coating liquid. For example, a die coating method, a spin coating method, a dip coating method, a roll coating method, Examples thereof include a bead coating method, a spray coating method, a bar coating method, a gravure coating method, an ink jet method, a screen printing method, and an offset printing method.

  The ratio of the electron-donating material and the electron-accepting material in the organic semiconductor layer 103 is a molar ratio, usually electron-donating material: electron-accepting material = 1: 0.5-7, preferably electron-donating property. Material: electron-accepting material = 1: 0.7-3.

  From the above, the laminate 110 can be obtained.

  Next, a process of forming the back electrode layer 104 on the organic semiconductor layer 103 (FIG. 2B) will be described.

  The back electrode layer 104 is formed on the organic semiconductor layer 103 and is an electrode facing the transparent electrode layer 102. As will be described later, the back electrode layer 104 is formed by spraying a dispersion liquid containing metal nanoparticles and a dispersion medium as droplets on the organic semiconductor layer 103 and drying and removing the dispersion medium. is there.

First, the dispersion liquid containing the metal nanoparticles to be used will be described.
The dispersion liquid containing metal nanoparticles according to this embodiment can be prepared by dispersing at least metal nanoparticles in a dispersion medium. The dispersion medium is not particularly limited as long as it does not dissolve the organic semiconductor layer 103. For example, water or alcohols can be used.

The metal nanoparticles according to this embodiment are preferably those in which the surface of nano-sized metal fine particles is coated with a protective agent and stably dispersed independently.
As a protective agent for metal nanoparticles according to this embodiment, an organic π-junction ligand is preferable. When such a protective agent is used, the conductivity of the obtained back electrode layer 104 can be improved.
As said organic (pi) junction ligand, the 1 type, or 2 or more types of compound chosen from the group which consists of a phthalocyanine derivative, a naphthalocyanine derivative, and a porphyrin derivative is preferable.
As the organic π-junction ligand, an amino group, an alkylamino group, a mercapto group, a hydroxyl group, a carboxyl group are used as substituents in order to improve coordination to metal nanoparticles and dispersibility in a dispersion medium. , Phosphine group, phosphonic acid group, sulfonic acid group, halogen group, selenol group, sulfide group, selenoether group, amide group, imide group, cyano group, nitro group, and salts thereof, at least one kind thereof It is preferable to have.
As a specific compound of the organic π-junction ligand, one or more selected from the following OTAN, OTAP, and OCAN are preferable.
OTAN: 2,3,11,12,20,21,29,30-octakis [(2-N, N-dimethylaminoethyl) thio] naphthalocyanine OTAP: 2,3,9,10,16,17,23 , 24-octakis [(2-N, N-dimethylaminoethyl) thio] phthalocyanine OCAN: 2,3,11,12,20,21,29,30-naphthalocyanine octacarboxylic acid As the bonding ligand, an organic π-conjugated ligand described in Patent Document 2 (WO 2011/114713 pamphlet) can be used.
A liquid phase reduction method is an example of a method for preparing a metal nanoparticle dispersion containing an organic π-junction ligand. In addition, the production of the organic π-junction ligand of this embodiment and the preparation of the metal nanoparticle dispersion containing the organic π-junction ligand should be performed according to the method described in paragraphs 0039 to 0060 of Patent Document 2. Can do.

As a metal used for the metal nanoparticle concerning this embodiment, metals, such as gold, silver, copper, and platinum, or an alloy which made these the main ingredients are mentioned, for example. Among these, gold and silver are preferable from the viewpoints of excellent light reflectance and further improvement in power generation efficiency of the obtained organic thin-film solar cell.
These metals or alloys can be used alone or in combination of two or more.

The average particle size of the metal nanoparticles is usually 3 nm to 500 nm, preferably 5 nm to 50 nm. When the average particle diameter of the metal nanoparticles is within the above range, fusion between particles is likely to occur, and the conductivity of the obtained back electrode layer 104 can be improved.
Here, the average particle diameter of the metal nanoparticles can be determined by measuring the particle diameter of the metal nanoparticles in the dispersion using a transmission electron microscope (TEM). For example, the average particle diameter can be calculated by measuring the particle diameters of 300 independent metal nanoparticles that are not overlapped among the particles observed in the TEM image.

  The content of the metal nanoparticles in the dispersion containing the metal nanoparticles according to the present embodiment is preferably 1% by mass or more and 80% by mass or less, more preferably 3% by mass with respect to 100% by mass of the dispersion. The content is 30% by mass or less. When the content of the metal nanoparticles is not less than the above lower limit value, it is easy to obtain an electrode having a necessary thickness. Further, when the content of the metal nanoparticles is not more than the above upper limit value, the fluidity of the dispersion liquid is improved, and the coating property of the dispersion liquid on the organic semiconductor layer 103 is improved.

  From the viewpoint of reducing the surface tension of the dispersion and improving the coating property on the organic semiconductor layer 103, the dispersion containing the metal nanoparticles according to the present embodiment preferably contains a fluorinated surfactant. Thereby, the back electrode layer 104 can be formed more uniformly on the organic semiconductor layer 103. As a result, it is possible to further suppress a decrease in power generation efficiency of the obtained organic thin film solar cell.

  As said fluorine-type surfactant, a commercially available fluorine-type surfactant can be used, for example. For example, NOVEC (registered trademark) manufactured by 3M Company, Mega-Fac (registered trademark) manufactured by Dainippon Ink and Chemicals, Surflon (registered trademark) manufactured by AGC Seimi Chemical Co., Ltd. and the like can be mentioned.

  The content of the fluorosurfactant is 0.01% by mass or more and 10% by mass or less, preferably 0.05% by mass or more and 1% by mass or less, with respect to 100% by mass of the dispersion. When the content of the fluorosurfactant is within the above range, the coating property of the dispersion liquid on the organic semiconductor layer 103 can be improved more effectively.

  The dispersion containing the metal nanoparticles according to the present embodiment contains other components in addition to the metal nanoparticles, the dispersion medium, and the fluorosurfactant as long as the effect of the present invention is not hindered. Also good. For example, a binder, antioxidant, a viscosity modifier, a rust preventive agent, etc. are mentioned.

  The dispersion containing the metal nanoparticles according to the present embodiment may be prepared by dispersing the metal nanoparticles in the dispersion medium using a known ultrasonic disperser, kneader, kneader, or the like. These components can be dispersed or dissolved to prepare a dispersion containing metal nanoparticles.

  Next, a method for applying metal nanoparticles onto the organic semiconductor layer 103 will be described.

  In the method of manufacturing the organic thin film solar cell 100 of the present invention, the organic semiconductor layer 103 is spray-coated with a dispersion liquid containing metal nanoparticles and a dispersion medium as droplets, and the dispersion medium is dried and removed, thereby removing the organic semiconductor. A back electrode layer 104 is formed on the layer 103.

The method for spray-coating the dispersion containing the metal nanoparticles and the dispersion medium as droplets on the organic semiconductor layer 103 is not particularly limited as long as it is a method for spray-coating the dispersion as droplets. For example, a spray coating method, an inkjet method, etc. are mentioned. These methods may be used alone or in combination. The spray coating method is a method in which the dispersion liquid is sprayed on the organic semiconductor layer 103 with compressed air, or the dispersion liquid itself is pressurized and sprayed on the organic semiconductor layer 103. The ink jet method is a method in which an ink cartridge of a commercially available ink jet printer is filled with a dispersion, and ink jet printing is performed on the organic semiconductor layer 103.
By these methods, a dispersion liquid containing metal nanoparticles and a dispersion medium can be spray-coated on the organic semiconductor layer 103 as droplets.

  When spraying the dispersion containing the metal nanoparticles and the dispersion medium as droplets on the organic semiconductor layer 103, the thickness of the back electrode layer 104 obtained is in the range of 0.05 μm to 1 μm. It is preferable to apply to. Thereby, the back electrode layer 104 can be sufficiently formed on the organic semiconductor layer 103 and the adhesion between the organic semiconductor layer 103 and the back electrode layer 104 can be improved. As a result, the power generation efficiency of the obtained organic thin film solar cell 100 can be improved.

After spraying and applying a dispersion liquid containing metal nanoparticles and a dispersion medium as droplets on the organic semiconductor layer 103, the back surface is maintained by drying at 20 to 100 ° C. for 10 seconds to 30 minutes, for example. The electrode layer 104 may be formed, or the back electrode layer 104 may be formed by drying and removing the dispersion medium by holding at 20 to 100 ° C. for 10 seconds to 30 minutes.
Note that the operation of spray-coating a dispersion liquid containing metal nanoparticles and a dispersion medium as droplets and the operation of drying and removing the dispersion medium may be performed continuously or may be performed separately. It is preferable to carry out continuously from the viewpoint of improving the productivity of the organic thin film solar cell 100.

In the manufacturing method of the organic thin film solar cell 100 according to the present embodiment, it is preferable that the back electrode layer 104 formed on the organic semiconductor layer 103 does not undergo a firing step.
In the conventional method for producing an organic thin film solar cell, while sintering metal nanoparticles, the back electrode layer formed on the photoelectric conversion semiconductor layer is used to eliminate the protective agent present on the surface of the metal nanoparticles. The baking process was performed. For example, in patent document 1 (Unexamined-Japanese-Patent No. 2012-147014), after apply | coating the dispersion liquid containing a metal nanoparticle on a photoelectric conversion semiconductor layer, the obtained coating film is made into the temperature of 130-400 degreeC for 10 minutes. Hold for 1 hour and fire.

However, according to the study by the present inventors, the back electrode layer 104 obtained by the method for manufacturing the organic thin-film solar cell 100 according to the present embodiment suppresses a decrease in power generation efficiency when the firing step is not performed. I found out. Therefore, in the method for manufacturing the organic thin-film solar cell 100 according to the present embodiment, it is preferable that the back electrode layer 104 formed on the organic semiconductor layer 103 is not subjected to a firing step.
In the present embodiment, the firing step refers to a step of holding at a temperature of 130 ° C. or higher for 10 minutes or longer, and does not include the firing operation for decomposing and removing the dispersion medium as described above.

<Organic thin film solar cell>
FIG. 1 is a cross-sectional view illustrating an example of the configuration of an organic thin-film solar cell 100 according to an embodiment of the present invention.
The organic thin film solar cell 100 according to the present embodiment has a configuration in which at least a transparent electrode layer 102, an organic semiconductor layer 103, and a back electrode layer 104 are laminated in this order on a transparent substrate 101. Moreover, the organic thin film solar cell 100 which concerns on this embodiment can be obtained with the manufacturing method of the organic thin film solar cell of the said invention.

  In the organic thin film solar cell 100 according to the present embodiment, in addition to the constituent members described above, constituent members generally employed in the organic thin film solar cell may be provided as necessary. For example, functional layers such as a barrier layer, a protective layer, a strength support layer, an antifouling layer, a high light reflection layer, a light containment layer, and a sealing material layer may be provided. Further, an adhesive layer may be provided between the functional layers depending on the layer configuration.

As mentioned above, although embodiment of this invention was described, these are illustrations of this invention and various structures other than the above are also employable.
Further, the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within a scope that can achieve the object of the present invention are included in the present invention.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these.

Example 1
A glass substrate obtained by patterning ITO was used. The power generation element portion was 2 × 2 mm in size.
A TiOx film having a thickness of 20 nm was formed on the ITO on the glass substrate by the following method using a sol-gel method. First, titanium [IV] isopropoxide, acetylacetone, acetic acid and ethanol were mixed at a molar ratio of 1: 0.3: 0.2: 200 and left at room temperature for 12 hours. Then, it spin-coated on the conditions of 6000 rpm for 60 seconds on the glass substrate, and formed by heat-processing at 150 degreeC for 1 hour.
Poly 3-hexylthiophene (P3HT, manufactured by Merck, lisicon SP001 EF430602) and a fullerene derivative (PC61BM: phenyl _{-C 61} - butanoic acid - methyl ester, Luminescence Technology Co., PC61BM LT-S905) a 5: formulation 4 It was dissolved in a chlorobenzene solvent at a ratio. Next, the obtained P3HT / PC61BM solution was spin-coated on the TiOx film formed on the ITO under the conditions of 700 rpm for 60 seconds and dried to form a P3HT / PC61BM layer having a thickness of 200 nm.
Next, a dispersion of poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (4-styrenesulfonic acid) (PSS) on the P3HT / PC61BM layer (manufactured by HC Starck Ltd., CLEVIOS PAI408) A solution obtained by adding 0.5 wt% of a surfactant (TrionX-100 manufactured by SIGMA Aldrich) to the substrate was spin-coated under the conditions of 2000 rpm and 60 seconds, and then dried to form a PEDOT / PSS layer having a thickness of 50 nm. .

A dispersion containing gold nanoparticles was prepared by the following method.
As a gold nanoparticle protective agent, OTAN was used. 82 mg of chloroauric acid manufactured by Tanaka Kikinzoku Co., Ltd. was dissolved in 100 mL of ion exchange water to prepare a 5.27 mM chloroauric acid aqueous solution. Then, 2.5 mg of OTAN was dissolved in 4 mL of ion exchange water to prepare an OTAN aqueous solution. Moreover, 77 mg of Rongalite manufactured by Nacalai Tesque was dissolved in 1 mL of ion-exchanged water to prepare a 0.5 mM Rongalite aqueous solution. 95 mL of the prepared aqueous chloroauric acid solution and 4 mL of the OTAN aqueous solution were mixed, 1 mL of Rongalite aqueous solution was added thereto, and the mixture was heated to 80 ° C. When the gold nanoparticles were sufficiently grown, the heating was stopped to obtain 100 mL of a 5 mM aqueous solution of gold nanoparticles.
The gold nanoparticle aqueous solution was centrifuged to remove the supernatant. To this, 190 μL of ion-exchanged water and 10 μL of formic acid were added to dissolve the precipitate. This solution was filtered through a filter having a pore size of 0.22 μm to obtain a dispersion containing 2.5 M gold nanoparticles (average particle diameter of gold nanoparticles: 15 nm).

The dispersion containing the gold nanoparticles was adjusted to 2.0 M with pure water. Next, a solution obtained by diluting a fluorosurfactant (manufactured by 3M: NOVEC FC4430) to 0.2% by mass with pure water is prepared, and this solution and a dispersion containing gold nanoparticles are mixed in a volume of 1: 1. Thus, a dispersion containing gold nanoparticles for spray coating was obtained (content of fluorosurfactant: 0.1 mass%, content of metal nanoparticles: 15 mass%).
On the PEDOT / PSS layer obtained above, a mask with an opening in the electrode portion is placed, and the prepared gold nanoparticles are included using an air gun spray (GSI Creos, Mr. Airbrush Custom 0.18). The dispersion was spray applied. Then, the 200-nm-thick back surface electrode layer was formed by drying for 10 minutes.

  The obtained organic thin film solar cell element was frame-sealed with a UV curable epoxy resin with a grooved glass cap to obtain an organic thin film solar cell.

(Evaluation)
About the obtained organic thin-film solar cell, a sample is made at a position where light illuminance becomes 100 mW / cm ² using a simple solar simulator, TYPE: PEC-L10, air mass filter AM1.5G manufactured by Pexel Technology. Was set and irradiated with continuous light of the standard solar spectrum. The power generation characteristics were determined by measuring the IV curve using a Keithley 2400 source meter after 30 minutes. The power generation efficiency was 1.1%.

(Example 2)
A glass substrate obtained by patterning ITO was used. The power generation element portion was 2 × 2 mm in size.
On ITO, a dispersion of poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (4-styrenesulfonic acid) (PSS) (HC Starck Ltd., CLEVIOS PAI408) at 2000 rpm for 60 seconds. A 50 nm thick PEDOT / PSS layer was formed by spin coating under conditions, followed by drying at 200 ° C. for 10 minutes.
Then, poly 3-hexylthiophene (P3HT, manufactured by Merck, lisicon SP001 EF430602) and a fullerene derivative (PC61BM: phenyl _{-C 61} - butanoic acid - methyl ester, Luminescence Technology Co., PC61BM LT-S905) a 1: 1 It was made to melt | dissolve in the chlorobenzene solvent by the compounding ratio of. Next, the obtained P3HT / PC61BM solution is spin-coated on the PEDOT / PSS layer at 2000 rpm for 60 seconds, and then dried under a nitrogen gas atmosphere at 120 ° C. for 10 minutes to obtain a film thickness of 120 nm. The P3HT / PC61BM layer was formed.
Next, heat treatment was performed at 150 ° C. for 10 minutes in a nitrogen atmosphere. Subsequently, on the obtained P3HT / PC61BM layer, a mask with an opening in the electrode portion was placed, and the air gun spray (GSI Creos, Mr. Airbrush Custom .18) was used to spray-disperse a dispersion containing gold nanoparticles prepared as in Example 1. Then, the 200-nm-thick back surface electrode layer was formed by drying for 10 minutes.

  The obtained organic thin film solar cell element was frame-sealed with a UV curable epoxy resin with a grooved glass cap to obtain an organic thin film solar cell.

(Evaluation)
The characteristic evaluation was performed in the same manner as in Example 1. The power generation efficiency was 0.7%.

Example 3
A glass substrate obtained by patterning ITO was used. The power generation element portion was 2 × 2 mm in size.
A dispersion of poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (4-styrenesulfonic acid) (PSS) is spin-coated on ITO under the conditions of 1600 rpm for 60 seconds, and then 200 ° C. A PEDOT / PSS layer having a thickness of 50 nm was formed by drying for 10 minutes.
Poly 3-hexylthiophene was then dissolved in a chlorobenzene solvent. Next, the obtained P3HT solution was spin-coated on the PEDOT / PSS layer at 2500 rpm for 30 seconds, and then dried to form a P3HT layer having a thickness of 120 nm.
Then, fullerene derivative (PC61BM: phenyl _{-C 61} - methyl ester - butanoic acid) was dissolved in dichloroethane solvent. Next, the obtained PC61BM solution was spin-coated on the P3HT layer formed on the ITO under conditions of 4000 rpm and 10 seconds, and then dried to form a PC61BM layer having a thickness of 50 nm.
Next, heat treatment was performed at 150 ° C. for 10 minutes in a nitrogen atmosphere.

Subsequently, a dispersion containing gold nanoparticles was prepared by the following method.
OCAN was used as a protective agent for gold nanoparticles. 82 mg of chloroauric acid manufactured by Tanaka Kikinzoku Co., Ltd. was dissolved in 100 mL of ion exchange water to prepare a 5.27 mM chloroauric acid aqueous solution. Next, 2.5 mg of OCAN was dissolved in 4 mL of ion exchange water to prepare an OCAN aqueous solution. Moreover, 77 mg of Rongalite manufactured by Nacalai Tesque was dissolved in 1 mL of ion-exchanged water to prepare a 0.5 mM Rongalite aqueous solution. 95 mL of the prepared aqueous chloroauric acid solution and 4 mL of the OCAN aqueous solution were mixed, 1 mL of Rongalite aqueous solution was added thereto, and the mixture was heated to 80 ° C. When the gold nanoparticles were sufficiently grown, the heating was stopped to obtain 100 mL of a 5 mM aqueous solution of gold nanoparticles.
The gold nanoparticle aqueous solution was centrifuged to remove the supernatant. 190 μL of ion exchange water and 10 μL of trimethylamine were added to dissolve the precipitate. This solution was filtered through a filter having a pore size of 0.22 μm to obtain a dispersion containing 2.5 M gold nanoparticles (average particle diameter of gold nanoparticles: 15 nm).

The dispersion containing the gold nanoparticles was adjusted to 2.0 M with pure water. Next, a solution obtained by diluting a fluorosurfactant (manufactured by 3M: NOVEC FC4430) to 0.2% by mass with pure water is prepared, and this solution and a dispersion containing gold nanoparticles are mixed in a volume of 1: 1. Thus, a dispersion containing gold nanoparticles for spray coating was obtained (content of fluorosurfactant: 0.1 mass%, content of metal nanoparticles: 15 mass%).
On the PC61BM layer obtained above, a mask with an opening in the electrode portion is placed, and a dispersion containing gold nanoparticles is sprayed using an air gun spray (GSI Creos, Mr. Airbrush Custom 0.18). Applied. Then, the 200-nm-thick back surface electrode layer was formed by drying on 40 degreeC and the conditions for 10 minutes.

  The obtained organic thin film solar cell element was frame-sealed with a UV curable epoxy resin with a grooved glass cap to obtain an organic thin film solar cell.

(Evaluation)
The characteristic evaluation was performed in the same manner as in Example 1. The power generation efficiency was 1.4%.

Example 4
The organic thin film solar cell produced in Example 3 was heat-treated in nitrogen at 150 ° C. for 15 minutes.
(Evaluation)
The characteristic evaluation was performed in the same manner as in Example 1. The power generation efficiency was 0.6%.

(Comparative Example 1)
A glass substrate obtained by patterning ITO was used. The power generation element portion was 2 × 2 mm in size.
In the same manner as in Example 1, the layers up to the PEDOT / PSS layer were formed.

  Subsequently, an Ag paste (manufactured by Dupont, 4922N) was applied on the obtained PEDOT / PSS layer by a bar coating method using a glass rod. Then, the 200-nm-thick back surface electrode layer was formed by drying for 10 minutes.

  The obtained organic thin film solar cell element was frame-sealed with a UV curable epoxy resin with a grooved glass cap to obtain an organic thin film solar cell.

(Evaluation)
The characteristic evaluation was performed in the same manner as in Example 1. There were many leaks, and the power generation efficiency was as low as 0.1% or less.

(Comparative Example 2)
In the same manner as in Example 1, up to the PEDOT / PSS layer was formed. The dispersion containing gold nanoparticles prepared in the same manner as in Example 1 was suspended on the PEDOT / PSS layer obtained above with a spatula, and the end including the region of the power generation element portion of about 2 × 2 mm was taken out. It applied to the ITO electrode pad. Thereafter, the back electrode layer was formed by drying at 40 ° C. for 5 minutes. The film thickness was uneven and was approximately in the range of 200 to 600 nm. In the process of placing the liquid and drying, a small portion that penetrates the ITO electrode on the glass side was generated. Moreover, the film thickness unevenness of the electrode surface also occurred.

  The obtained organic thin film solar cell element was frame-sealed with a UV curable epoxy resin with a grooved glass cap to obtain an organic thin film solar cell.

(Evaluation)
The characteristic evaluation was performed in the same manner as in Example 1. There were many leaks, and the power generation efficiency was as low as 0.1% or less.

100 Organic Thin Film Solar Cell 101 Transparent Substrate 102 Transparent Electrode Layer 103 Organic Semiconductor Layer 104 Back Electrode Layer 110 Laminate

Claims (14)

A method for producing an organic thin-film solar cell in which at least a transparent electrode layer, an organic semiconductor layer, and a back electrode layer are laminated in this order on a transparent substrate,
Preparing a laminate in which the transparent electrode layer and the organic semiconductor layer are laminated in this order on the transparent substrate;
Forming a back electrode layer on the organic semiconductor layer by spray-coating a dispersion liquid containing metal nanoparticles and a dispersion medium as droplets on the organic semiconductor layer and drying and removing the dispersion medium; ,
A method for producing an organic thin film solar cell, comprising: In the manufacturing method of the organic thin-film solar cell of Claim 1,
The manufacturing method of the organic thin film solar cell in which the said dispersion liquid containing a metal nanoparticle and a dispersion medium contains an organic (pi) junction ligand. In the manufacturing method of the organic thin-film solar cell of Claim 1 or 2,
The said back electrode layer formed on the said organic-semiconductor layer does not pass a baking process, The manufacturing method of an organic thin-film solar cell. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 3,
The said dispersion liquid is a manufacturing method of an organic thin-film solar cell containing a fluorine-type surfactant. In the manufacturing method of the organic thin-film solar cell of Claim 4,
The manufacturing method of the organic thin-film solar cell whose content of the said fluorosurfactant is 0.01 to 10 mass% with respect to 100 mass% of said dispersion liquids. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 5,
The manufacturing method of the organic thin-film solar cell whose content of the said metal nanoparticle is 1 to 80 mass% with respect to 100 mass% of said dispersion liquids. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 6,
The surface of the metal nanoparticles is coated with a protective agent containing one or more organic π-junction ligands selected from the group consisting of phthalocyanine derivatives, naphthalocyanine derivatives and porphyrin derivatives, an organic thin film solar cell Manufacturing method. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 7,
The said metal nanoparticle is a manufacturing method of the organic thin-film solar cell containing 1 type, or 2 or more types of metals selected from the group which consists of gold | metal | money, silver, copper, and platinum. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 8,
The average particle diameter of the said metal nanoparticle is a manufacturing method of the organic thin film solar cell which is 3 nm or more and 500 nm or less. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 9,
The organic semiconductor layer is a method for producing an organic thin-film solar cell, in which an electron-accepting layer and an electron-donating layer are laminated. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 10,
The manufacturing method of an organic thin-film solar cell which spray-coats the said dispersion liquid on the said organic-semiconductor layer using at least 1 sort (s) selected from the spray-coating method and the inkjet method. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 11,
A method for producing an organic thin-film solar cell, wherein the back electrode layer is formed on the organic semiconductor layer so that the thickness of the back electrode layer is in a range of 0.05 μm or more and 1 μm or less. In the manufacturing method of the organic thin-film solar cell as described in any one of Claims 1 thru | or 12,
A method for producing an organic thin-film solar cell, wherein the dispersion medium is at least one selected from water and alcohols.   The organic thin film solar cell obtained by the manufacturing method of the organic thin film solar cell as described in any one of Claims 1 thru | or 13.

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