JP2006245074A - Organic thin film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic thin film solar cell having a photoelectric conversion layer having good smoothness during film formation and good dispersibility of an organic semiconductor material.
The present invention relates to a substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer, and a photoelectric conversion layer formed on the photoelectric conversion layer. An organic thin film solar cell having a second electrode layer that is an electrode facing one electrode layer, wherein the photoelectric conversion layer contains a conductive compound obtained by solidifying an ionic liquid and an organic semiconductor material. The said subject is solved by providing the organic thin-film solar cell characterized by the above-mentioned.
[Selection] Figure 1

Description

  The present invention relates to an organic thin film solar cell capable of forming a photoelectric conversion layer by a wet coating method.

  An organic thin film solar cell is a solar cell in which an organic thin film having an electron donating function and an electron accepting function is disposed between two different electrodes, and has a manufacturing process compared to an inorganic solar cell represented by silicon or the like. It has an advantage that it is easy and can be enlarged at low cost. However, since the energy conversion efficiency is low, it has been difficult to put it to practical use. Therefore, in the organic thin-film solar cell, increasing the energy conversion efficiency is the biggest issue.

  Recently, in order to improve the energy conversion efficiency of organic thin film solar cells, attempts have been made to make use of the characteristics of organic materials used in organic thin films, which are disclosed in Non-Patent Document 1 and Non-Patent Document 2. .

  Examples of the organic thin film solar cell as described above include an example of a bilayer type organic thin film solar cell in which the organic thin film is composed of an electron transport layer and a hole transport layer. In general, a bilayer organic thin film solar cell includes a transparent substrate, a transparent electrode formed on the transparent substrate, a hole transport layer and an electron acceptor that are formed on the transparent electrode and function as an electron donor. A photoelectric conversion layer composed of a functioning electron transport layer and a counter electrode which is formed on the photoelectric conversion layer and is opposed to the transparent electrode. In this bilayer organic thin-film solar cell, a p-type organic semiconductor is used for the hole transport layer that functions as an electron donor, and an n-type organic semiconductor is used for the electron transport layer that functions as an electron acceptor. A pn junction is formed at the interface of the layers and contributes to photoelectric conversion.

  Further, as a method for expanding the pn junction portion in order to improve energy conversion efficiency, there is a method in which a p-type organic semiconductor and an n-type organic semiconductor are not simply stacked but mixed. By mixing the p-type organic semiconductor and the n-type organic semiconductor, a pn junction at the molecular level is widely formed in the film, so that the volume that can contribute to photoelectric conversion increases.

  As a method for forming a photoelectric conversion layer composed of such a p-type organic semiconductor and an n-type organic semiconductor, two methods of vapor deposition and wet coating are generally used. Especially, since the photoelectric conversion layer can be formed in the atmosphere, the wet coating method has an advantage that not only the initial investment of facilities can be suppressed, but also it is advantageous in terms of increasing the area.

  However, since organic materials such as conductive polymers used as p-type organic semiconductors and n-type organic semiconductors have low solubility in organic solvents, it is difficult to prepare a coating solution when forming a photoelectric conversion layer. In addition, there are problems such as poor film smoothness after film formation and low dispersibility of each material when mixing a p-type organic semiconductor and an n-type organic semiconductor.

  In addition, conventional organic solvents are mainly diluted solvents such as chloroform, dichloroethane, xylene, and toluene, and there have been few proposals for media having excellent solubility and dispersibility of organic materials such as conductive polymers. There is no current situation.

MATERIAL STAGE vol.2, No.9 2002 p.37-42 Junichi Nakamura et al. "Organic thin-film solar cells-utilization of donor-acceptor interaction" Applied Physics Vol.71 No.4 (2002) p.425-428 Akinori Kuno "Current Status and Prospects of Organic Solar Cells"

  The present invention has been made in view of the above problems, and provides an organic thin-film solar cell having a photoelectric conversion layer having good smoothness during film formation and good dispersibility of an organic semiconductor material. This is the main purpose.

  In order to achieve the above object, the present inventors are a medium excellent in solubility and dispersibility of an organic semiconductor material used for a photoelectric conversion layer, and contribute to solar cell characteristics or provide solar cell characteristics. We searched for media that could be maintained. As a result, the inventors have found that an ionic liquid that can be solidified is effective, and have completed the present invention.

  That is, the present invention includes a substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer, and the first electrode formed on the photoelectric conversion layer. An organic thin film solar cell having a second electrode layer that is an electrode facing the layer, wherein the photoelectric conversion layer contains a conductive compound obtained by solidifying an ionic liquid and an organic semiconductor material An organic thin film solar cell is provided.

  In the present invention, if the photoelectric conversion layer contains a conductive compound obtained by solidifying an ionic liquid and an organic semiconductor material, the photoelectric conversion layer is formed by dissolving or dispersing the organic semiconductor material in the ionic liquid. A photoelectric conversion layer can be obtained by solidifying after applying this using a coating liquid. Usually, the ionic liquid is capable of sufficiently dissolving or dispersing the organic semiconductor material, and in the photoelectric conversion layer obtained by solidifying such a coating liquid for forming a photoelectric conversion layer, a photoelectric conversion layer is used. It is possible to include enough organic semiconductor material to function. In addition, the photoelectric conversion layer is different from the conventional one in which a coating solution with a very small amount of organic semiconductor material dissolved is applied and a large amount of organic solvent is removed and solidified to form a film. Since the ionic liquid, which is a medium, is solidified by light irradiation or heating after coating, the film surface is smooth and the organic semiconductor material has good dispersibility. It can be a conversion layer. Furthermore, the ionic liquid used itself can function as an organic semiconductor in the photoelectric conversion layer. Thereby, it can be set as an organic thin film solar cell with high energy conversion efficiency.

  In the present invention, the ionic liquid is preferably an imidazolium salt. This is because there are few types of ionic liquids that have been found so far, and imidazolium salts are common among ionic liquids that are currently known, and are easily applied to the present invention.

  Furthermore, in the present invention, the ionic liquid preferably has a polymerizable group. When forming a photoelectric conversion layer using a coating liquid for forming a photoelectric conversion layer containing an ionic liquid and an organic semiconductor material, the ionic liquid has a polymerizable group so that the ionic liquid is polymerized. This is because a film can be formed, smoothness and dispersibility of the organic semiconductor material are good, and a photoelectric conversion layer with high film strength can be formed.

  In the present invention, the ionic liquid is represented by the general formula (1).

(Wherein, X ^- is ^{Br -,} PF ₆ - or ^{_{(CF 3 SO 2) 2 N}} - (TFSI -) represents one of, n represents represents 1-100.) Is a compound represented by Is preferred.

  The present invention also includes a first electrode layer forming step of forming a first electrode layer on a substrate, a photoelectric conversion layer forming step of forming a photoelectric conversion layer on the first electrode layer, and the photoelectric conversion layer. And a second electrode forming step of forming a second electrode layer that is an electrode opposite to the first electrode layer, wherein the photoelectric conversion layer forming step is performed by using an ionic liquid. A method for producing an organic thin-film solar cell, comprising: applying a coating liquid for forming a photoelectric conversion layer in which an organic semiconductor material is dissolved or dispersed as a medium, and solidifying the ionic liquid. provide.

  According to the present invention, the ionic liquid used for the photoelectric conversion layer forming coating liquid is capable of sufficiently dissolving or dispersing the organic semiconductor material, and such a photoelectric conversion layer forming coating liquid. The photoelectric conversion layer formed using can contain an organic semiconductor material sufficient to function as a photoelectric conversion layer. Also, unlike the conventional one in which a coating solution having an extremely small amount of organic semiconductor material dissolved is applied and a large amount of organic solvent is removed and solidified to form a film, in the present invention, a coating for forming a photoelectric conversion layer is used. Since the ionic liquid is solidified by light irradiation or heating after application of the working solution, the photoelectric conversion layer has good film surface smoothness and good dispersibility of the organic semiconductor material. Can be formed. Furthermore, the ionic liquid used itself can function as an organic semiconductor in the photoelectric conversion layer. Thereby, an organic thin film solar cell with high energy conversion efficiency can be manufactured.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to form a photoelectric converting layer with favorable smoothness and the dispersibility of an organic-semiconductor material, and it can be set as an organic thin film solar cell with high energy conversion efficiency.

  The present invention includes an organic thin film solar cell and a method for producing the same. Hereinafter, the organic thin-film solar cell and the manufacturing method thereof of the present invention will be described in detail.

A. First, the organic thin film solar cell of the present invention will be described.

  The organic thin film solar cell of the present invention is formed on a substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer, and the photoelectric conversion layer, An organic thin-film solar cell having a second electrode layer that is an electrode facing the first electrode layer, wherein the photoelectric conversion layer contains a conductive compound obtained by solidifying an ionic liquid and an organic semiconductor material It is characterized by doing.

  In the present invention, if the photoelectric conversion layer contains a conductive compound obtained by solidifying an ionic liquid and an organic semiconductor material, the photoelectric conversion layer is formed by dissolving or dispersing the organic semiconductor material in the ionic liquid. A photoelectric conversion layer can be obtained by solidifying after applying this using a coating liquid. Usually, the ionic liquid is capable of sufficiently dissolving or dispersing the organic semiconductor material, and in the photoelectric conversion layer obtained by solidifying such a coating liquid for forming a photoelectric conversion layer, a photoelectric conversion layer is used. It is possible to include enough organic semiconductor material to function.

  In addition, the photoelectric conversion layer is different from the conventional one in which a coating solution with a very small amount of organic semiconductor material dissolved is applied and a large amount of organic solvent is removed and solidified to form a film. Since the ionic liquid, which is a medium, is solidified by light irradiation or heating after coating, the film surface is smooth and the organic semiconductor material has good dispersibility. It can be a conversion layer.

  Furthermore, since the ionic liquid used itself can contribute to a photoelectric conversion reaction in the photoelectric conversion layer, an organic thin film solar cell with high energy conversion efficiency can be obtained.

FIG. 1 is a schematic sectional view showing an example of the organic thin film solar cell of the present invention. As shown in FIG. 1, the organic thin film solar cell of the present invention includes a substrate 1, a first electrode layer 2 formed on the substrate 1, and a photoelectric conversion layer 3 formed on the first electrode layer 2. And a second electrode layer 4 formed on the photoelectric conversion layer 3 and facing the first electrode layer 2.
Hereinafter, each structure of such an organic thin film solar cell is demonstrated.

1. Photoelectric Conversion Layer First, the photoelectric conversion layer used in the present invention will be described. In the present invention, the photoelectric conversion layer contains a conductive compound obtained by solidifying an ionic liquid and an organic semiconductor material.

  According to the present invention, since the photoelectric conversion layer contains the conductive polymer formed by solidifying the ionic liquid and the organic semiconductor material, the photoelectric conversion layer is formed by dissolving or dispersing the organic semiconductor material in the ionic liquid. After applying the coating liquid and applying it, the organic semiconductor material and the ionic liquid are solidified to obtain a photoelectric conversion layer. Usually, the ionic liquid can sufficiently dissolve or disperse the organic semiconductor material, and in the photoelectric conversion layer obtained by solidifying these, an organic semiconductor material sufficient to function as a photoelectric conversion layer is provided. It can be contained.

  Conventionally, since the solubility or dispersibility of the organic semiconductor material in the solvent is poor, the organic semiconductor material is applied using a coating solution with a very small amount of dissolution, and a large amount of the solvent is removed to solidify and form. Since the film was formed, there was a problem that the film was not smooth after film formation. In particular, when a photoelectric conversion layer is formed using a coating liquid in which an organic semiconductor material having an electron donating property and an organic semiconductor material having an electron accepting property are mixed, if the dispersibility of the organic semiconductor material is poor, photoelectric conversion Since it becomes difficult to form a pn junction in the layer, there is also a disadvantage that the energy conversion efficiency is lowered. However, in the present invention, a coating solution for forming a photoelectric conversion layer using an ionic liquid having a good solubility and dispersibility of an organic semiconductor material as a medium is applied, and the ionic liquid is solidified by light irradiation or heating. Therefore, a photoelectric conversion layer having good smoothness after film formation and good dispersibility of the organic semiconductor material can be obtained.

Further, the ionic liquid itself can function as an organic semiconductor in the photoelectric conversion layer. Thereby, it can be set as an organic thin film solar cell with high energy conversion efficiency.
Hereinafter, the material which comprises such a photoelectric converting layer is demonstrated.

(1) Ionic liquid First, the ionic liquid used in the present invention will be described.

  Generally, a salt is solid at room temperature, but when heated, it dissolves at a certain temperature and becomes a liquid (molten salt). However, the high melting point of several hundred degrees Celsius became a barrier, and application to a wide range did not progress. In contrast, recently, a system that uses an organic cation and an anion to become a liquid at room temperature has been found. These are called room temperature molten salts or ionic liquids.

There are various configurations of ions forming the ionic liquid, for example, a combination of ethylmethylimidazolium cation and BF ₄ ⁻ , PF ₆ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ (also referred to as TFSI ⁻ ) or the like. The system becomes liquid at room temperature. Furthermore, when a TFSI anion is used, it is a salt that is insoluble in water although it is a salt.

  Since ionic liquids have a high ion density that cannot be achieved by general solutions and have high ion mobility, they exhibit extremely high ionic conductivity and are good solvents for various salts. Expected. In addition, the ionic liquid is useful as a solvent, and in many cases, the ionic liquid has solubility in materials that have been extremely low in solubility in various solvents.

  It is particularly noteworthy that the polymer material, particularly the conjugated polymer material has solubility or dispersibility. The majority of photoelectric conversion materials used in organic devices including organic thin-film solar cells are developed polymers of this conjugated system. The higher the performance as a photoelectric conversion material, the more soluble and dispersible it is in the solvent. Tend to be low. In order to form a photoelectric conversion layer by a wet coating method with good cost performance, many efforts have been made so far to improve the solubility and dispersibility of materials, and the importance is very high.

  Examples of such ionic liquids include ionic liquids "Frontiers and Future of Development" p. 196-201 Supervised by Hiroyuki Ohno et al.

  The ionic liquid used in the present invention is not particularly limited as long as the organic semiconductor material described later has good solubility or dispersibility and has conductivity when the ionic liquid is solidified. Further, as described above, the ionic liquid is composed of a cation and an anion.

  Such cations of the ionic liquid are roughly classified into aromatic cations and aliphatic cations. For example, imidazolium, pyridinium, pyrazolium, or the like can be used as the aromatic cation, and ammonium or the like can be used as the aliphatic cation.

Examples of the imidazolium include ethylmethylimidazolium (EMI), butylmethylimidazolium (BMI), octylmethylimidazolium (OMI), and the like.
Examples of the pyridinium include 1-butylpyridinium salt (BP).
Furthermore, examples of the ammonium include asymmetric quaternary ammonium such as trimethylpropylammonium (TMPA).

On the other hand, the anion of the ionic liquid used in the present invention is not particularly limited as long as it forms a salt with the above cation and the salt becomes liquid at room temperature. For example, (CF ₃ SO ₂ ) ₂ N ⁻ (TFSI ^- and also referred _{to), (CF 3 SO 2)} 2 C - ( hereinafter, TFSM ^- and also referred _{to), (CF 3 SO 3)} - ( hereinafter, TF ^- and also referred _{to), n-C 4 F 9} SO 3 - , _PF ⁶ -, BF ₄ ^-, etc. of the fluorine-containing anion; N- cyclohexyl-2-aminoethanesulfonic acid anion (hereinafter, CHES ^- and also referred to), 2-hydroxy-3-morpholinopropane-sulfonic acid anion (hereinafter, MOPSO ^- and also referred to), N, N-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid anion (hereinafter, BES ^- and also referred to) sul such Examples include phosphonic acid anions. In addition, as the anion, NO ₃ ⁻ , SCN ⁻ , Br ⁻ , AlCl ₄ ⁻ or the like can be used.

  Further, as the ionic liquid used in the present invention, a Zwitterionic (zwitter ion) type ionic liquid in which both a cation and an anion are immobilized in the molecule can be used. For example, 1-ethylimidazolium-3-n-propanesulfonate (EIm3S), 1-ethylimidazolium-3-n-butanesulfonate (EIm4S), and the like can be given.

In the present invention, among the above, it is preferable to use an imidazolium salt in which the anion of the ionic liquid is imidazolium. This is because there are few types of ionic liquids that have been found so far, and imidazolium salts are common among ionic liquids that are currently known, and are easily applied to the present invention. Examples of the imidazolium salt include a combination of ethylmethylimidazolium (EMI) or butylmethylimidazolium (BMI) and PF ₆ ⁻ , BF ₄ ⁻ , or (CF ₃ SO ₂ ) ₂ N ⁻ (TFSI ⁻ ). Are preferably used.

  In the present invention, the ionic liquid preferably has a polymerizable group. When forming a photoelectric conversion layer using a coating liquid for forming a photoelectric conversion layer containing an ionic liquid and an organic semiconductor material described later, the ionic liquid has a polymerizable group, thereby polymerizing the ionic liquid. This is because it is possible to form a photoelectric conversion layer having excellent smoothness and dispersibility of the organic semiconductor material and higher film strength. Furthermore, the ionic liquid preferably has a polymerizable group at the molecular chain end.

  Such a polymerizable group is not particularly limited as long as it is a polymerizable functional group, and examples thereof include a vinyl group, a (meth) acryl group, an epoxy group, a styryl group, a methacryloyl group, and an allyl group. Further, it may be a photopolymerizable polymerizable group such as an oxetanyl group.

In the present invention, the ionic liquid is an imidazolium salt and preferably has a polymerizable group. Examples of such ionic liquid include vinylimidazole. In this case, as described above, the ionic liquid preferably has a polymerizable group such as a vinyl group or an acrylic group at the molecular chain terminal, but a polymerizable group such as a vinyl group or an acrylic group is present at the site of the ionic liquid. May be bonded, and a spacer may be introduced between the site of the ionic liquid and a polymerizable group such as a vinyl group or an acrylic group.
In particular, the ionic liquid used in the present invention is preferably a compound represented by the following general formula (1).

In the above general formula (1), X ^- is ^Br -, PF ₆ ^- represents either (TFSI) - or ^{_{(CF 3 SO 2) 2 N}} . Moreover, although n which shows the chain length of an alkyl chain can take arbitrary integers in the range of 1-100, it is preferable that it is the range of 1-20, and it is more preferable that it is the range of 2-10.

  This is because the compound represented by the general formula (1) has good solubility of the organic semiconductor material, high flexibility, and excellent followability and stability.

  In the present invention, the ionic liquid often functions as a medium in which an organic semiconductor material described later is dissolved or dispersed or a matrix in the photoelectric conversion layer, but functions as an organic semiconductor in the photoelectric conversion layer. There are also things. When the ionic liquid functions as an organic semiconductor, charge separation occurs between the organic semiconductor material described later, and thus an organic thin film solar cell with high energy conversion efficiency can be obtained.

(2) Conductive compound formed by solidifying ionic liquid Next, the conductive compound formed by solidifying the ionic liquid used in the present invention will be described. In the present invention, the conductive compound is formed by solidifying the ionic liquid.

  The methods for solidifying the ionic liquid are roughly classified into three methods. (I) a method in which a host polymer is impregnated with an ionic liquid to form a gel electrolyte, (ii) a method in which a polymer is formed by forming an ionic liquid, and (iii) the ionic liquid itself as a main chain and side It is a method of forming a polymer by fixing to a chain. In the following, description will be given separately.

(I) Method of forming a gel electrolyte by impregnating a host polymer with an ionic liquid The development of a gel electrolyte using an ionic liquid is the most widely used as solidification of an ionic liquid because of its ease of design and synthesis. There are many types of host polymers. Since the method for forming the gel electrolyte is performed by impregnating the host polymer with the ionic liquid, not only has the film forming ability, but also can be solidified without impairing the characteristics of the ionic liquid. It is done.

  As the host polymer used in the present invention, polymers generally used in gel electrolytes can be used. For example, polyvinylidene fluoride (PVdF), a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF) -HFP), Nafion (registered trademark), 2-hydroxyethyl methacrylate and the like.

  In addition, carbon nanotubes, which are organic semiconductor materials described later, can also be used as the host polymer. In this case, when the carbon nanotube is impregnated with the ionic liquid, the ionic liquid can be oriented by the interaction between the carbon nanotube and the ionic liquid. Therefore, the organic semiconductor material has good dispersibility and a uniform film. Can be formed.

  Specific examples of the gel electrolyte include those in which a fluorine-based polymer is impregnated with a Zwitterionic type ionic liquid.

  Here, in the method (i), the gel electrolyte is a conductive compound in the present invention.

(Ii) Method of forming a polymer by the formation of an ionic liquid The formation of a polymer by the formation of an ionic liquid means that when an ionic liquid with an opposite charge fixed to the end of the molecule is mixed, Since an ionic bond is formed at the terminal, a pseudo polymer is formed through the terminal ionic bond while maintaining high mobility of the main chain. However, in the above-described pseudo polymer, molecules having a relatively small molecular weight are bonded through ionic bonds, so that the mechanical strength may be inferior.

  Examples of the polymer formed by the formation of such an ionic liquid include a PEO / salt hybrid in which a salt structure is fixed to the end of polyethylene oxide (PEO) which is an ion conductive polymer. This PEO / salt hybrid becomes liquid at room temperature when the PEO chain is short.

  Here, in the method (ii), the pseudo polymer is the conductive compound in the present invention.

(Iii) A method of forming a polymer by fixing the ionic liquid itself to the main chain and side chain When the ionic liquid has a polymerizable group as described above, the ionic liquid is polymerized by light irradiation or heating. It can be made into a polymer and solidified.

  As the ionic liquid having such a polymerizable group, the same ionic liquid as that described in the column of the ionic liquid can be used.

  Moreover, since it describes in "B. manufacturing method of an organic thin film solar cell" mentioned later as a method of superposing | polymerizing an ionic liquid, description here is abbreviate | omitted.

  There are many bonding modes when polymerizing the above ionic liquid. For example, (a) the ionic liquid is fixed to the side chain, and a spacer molecule is introduced between the main chain and the ionic liquid. (B) a cationic polymer in which a cation of the ionic liquid is fixed to the main chain or the side chain, (c) ) Anionic polymer in which the anion of the ionic liquid is fixed to the main chain or side chain, (d) Zwitterionic type polymer in which the ionic liquid of Zwitterionic type is fixed to the main chain or side chain, (e) of the ionic liquid A polymer blend in which cations and anions are respectively fixed to different main chains or side chains; (f) a copolymer blend in which cations and anions of an ionic liquid are respectively fixed to the same main chain or side chains; Rimmer, and the like.

  Here, in the method (iii), polymers as shown in the above (a) to (f) are the conductive compounds in the present invention.

  In the present invention, the conductive compound obtained by solidifying the ionic liquid forms a polymer by fixing the ionic liquid itself to the main chain and the side chain among the methods for solidifying the ionic liquid. It is preferable that it is formed by the method. In this method, a film can be formed by polymerizing an ionic liquid, smoothness and dispersibility of the organic semiconductor material are good, and a photoelectric conversion layer having high film strength can be formed. It is.

  In the present invention, as the conductive compound obtained by solidifying the ionic liquid, in addition to the function as a medium and a matrix, flexibility, light resistance, thermal stability, moisture resistance, etc. when forming a film It is preferable to be excellent.

(3) Organic Semiconductor Material Next, the organic semiconductor material used in the present invention will be described. In the present invention, the organic semiconductor material has an electron donating property or an electron accepting property.

  The photoelectric conversion layer in the present invention has a conductive compound obtained by solidifying the ionic liquid and an organic semiconductor material. Moreover, in this invention, a photoelectric converting layer means the member which has a function which contributes to electric charge separation of an organic thin-film solar cell, and transports the produced | generated electron and a hole toward the electrode of an opposite direction, respectively. Specifically, when such a photoelectric conversion layer has at least one of a hole transport layer that functions as an electron donor or an electron transport layer that functions as an electron acceptor, the function of both an electron donor and an electron acceptor The case where it consists of an electron hole transport layer which has this can be mentioned. The kind of these photoelectric conversion layers is selected according to the kind of organic thin film solar cell.

  Specifically, as the type of organic thin film solar cell, the photoelectric conversion layer having either one of the electron donating function and the electron accepting function, that is, the electron transport layer or the hole transport layer, A Schottky-type organic thin-film solar cell that is disposed between the first electrode layer and the second electrode layer and uses a Schottky barrier between the electrode and such a photoelectric conversion layer, or an electron accepting and electron donating function As a set, a heterojunction organic thin film solar cell using a pn junction can be used.

  Furthermore, in heterojunction organic thin-film solar cells, a bilayer type having a structure in which an electron transport layer having an electron-accepting function and a hole transport layer having an electron-donating function are separately laminated, and electron donation There is a bulk heterojunction type using an electron-hole transport layer in which the functions of the electron accepting function and the electron accepting function are mixed in one layer.

  Hereinafter, the organic semiconductor material used for the photoelectric conversion layer will be described separately for each case where the type of the organic thin film solar cell is a Schottky type or a heterojunction type.

(I) In the case of a Schottky type organic thin film solar cell The photoelectric conversion layer in the present invention is a layer having either an electron donating function or an electron accepting function, that is, either an electron transporting layer or a hole transporting layer. Thus, a Schottky-type organic thin-film solar cell that obtains a photocurrent using such a Schottky barrier formed at the interface between the photoelectric conversion layer and the electrode can be obtained.

  For example, when the photoelectric conversion layer is a hole transport layer, a Schottky barrier is formed at the interface between the first electrode layer and the second electrode layer with the smaller work function. Photocharge separation can occur. On the other hand, when the photoelectric conversion layer is an electron transport layer, a photocurrent can be generated at the interface with the electrode having the higher work function of the first electrode layer and the second electrode layer described above.

  Thus, when it is set as a Schottky type organic thin film solar cell, if an organic-semiconductor material has an electron-donating property or an electron-accepting property, it will not specifically limit. Specifically, conductive polymers such as organic single crystals such as pentacene, poly-3-methylthiophene, polyacetylene, polyphenylene and derivatives thereof, polyphenylene vinylene and derivatives thereof, polysilane and derivatives thereof, polyalkylthiophene and derivatives thereof, and the like Derivatives thereof, porphyrin derivatives, phthalocyanine derivatives, merocyanine derivatives, synthetic pigments such as chlorophyll, organometallic polymers, and the like can be mentioned. The photoelectric conversion layer in the Schottky-type organic thin film solar cell is formed using either an electron-donating or electron-accepting organic semiconductor material. Among them, it is preferable that the charge mobility is high.

(Ii) In the case of a heterojunction type organic thin film solar cell As described above, the heterojunction type organic thin film solar cell can be divided into a bilayer type and a bulk heterojunction type. Hereinafter, the organic semiconductor material used for the photoelectric conversion layer will be described separately for a bilayer type and a bulk heterojunction type.

(In the case of bilayer type organic thin film solar cells)
Bi-layer organic thin-film solar cells are formed at the interface between the electron transport layer having the electron-accepting function and the hole transport layer having the electron-donating function separately as the photoelectric conversion layer. This is an organic thin-film solar cell that uses a pn junction to generate photocharge separation and obtain a photocurrent.

The organic semiconductor material for forming the electron transport layer is not particularly limited as long as it has a function as an electron acceptor. Specifically, CN-poly (phenylene-vinylene), MEH-CN-PPV, -CN group or -CF ₃ group-containing polymer, their -CF ₃ substituted polymer, poly (fluorene) derivative, fullerene such as C ₆₀ Examples thereof include materials such as derivatives, carbon nanotubes, perylene derivatives, polycyclic quinones, and quinacridones. Among them, it is preferable that the electron mobility is high.

  On the other hand, the organic semiconductor material for forming the hole transport layer is not particularly limited as long as it has a function as an electron donor. Specific examples include polyphenylene and derivatives thereof, polyphenylene vinylene and derivatives thereof, polysilane and derivatives thereof, polyalkylthiophene and derivatives thereof, porphyrin derivatives, phthalocyanine derivatives, and organometallic polymers. Among them, it is preferable that the hole mobility is high.

(For bulk heterojunction organic thin film solar cells)
The bulk heterojunction type organic thin film solar cell uses an electron hole transport layer having both electron accepting and electron donating functions as a photoelectric conversion layer, and utilizes a pn junction formed in the electron hole transport layer. It is an organic thin-film solar cell that causes photocharge separation and obtains a photocurrent.

  The organic semiconductor material for forming the electron-hole transport layer is not particularly limited as long as it is generally used in bulk heterojunction organic thin-film solar cells. The organic semiconductor material and the electron-accepting organic semiconductor material can be uniformly dispersed. The mixing ratio of the electron-donating organic semiconductor material and the electron-accepting organic semiconductor material is appropriately adjusted to an optimal mixing ratio depending on the material used.

  When forming such an electron-hole transport layer, a coating liquid for forming a photoelectric conversion layer in which an electron-donating organic semiconductor material and an electron-accepting organic semiconductor material are dispersed or dissolved in the ionic liquid is used. Will be used. Conventionally, since the solubility or dispersibility of the organic semiconductor material in the solvent is low, the dispersibility of the organic semiconductor material in the electron hole transport layer is also low, and it is difficult to form a pn junction. There has been a problem of lowering. However, in the present invention, the electron hole transport layer is formed using a coating liquid for forming a photoelectric conversion layer in which the dispersibility or solubility of the organic semiconductor material is good. The dispersibility of the semiconductor material can be improved. Therefore, since the pn junction is widely formed in the electron hole transport layer, the energy conversion efficiency can be improved.

The electron-accepting organic semiconductor material used for the electron-hole transport layer is not particularly limited as long as it has such a function. Specifically, CN-poly (phenylene-vinylene), MEH-CN-PPV, -CN group or -CF ₃ group-containing polymer, their -CF ₃ substituted polymer, poly (fluorene) derivative, C ₆₀ derivative, carbon Examples thereof include materials such as nanotubes, perylene derivatives, polycyclic quinones, and quinacridones. Among them, it is preferable that the electron mobility is high.

  On the other hand, the electron-donating organic semiconductor material is not particularly limited as long as it has such a function. Specific examples include polyphenylene and derivatives thereof, polyphenylene vinylene and derivatives thereof, polysilane and derivatives thereof, polyalkylthiophene and derivatives thereof, porphyrin derivatives, phthalocyanine derivatives, and organometallic polymers. Among them, it is preferable that the hole mobility is high.

(4) Others When the organic thin film solar cell of the present invention is a bilayer type of a Schottky type or a heterojunction type, the film thickness of the photoelectric conversion layer is within the range of 0.1 nm to 1500 nm. Especially, it is preferable that it exists in the range of 5 nm-300 nm. When the film thickness is thicker than the above range, the film resistance of the photoelectric conversion layer may be increased. On the other hand, when the film thickness is thinner than the above range, a short circuit occurs between the first electrode layer and the second electrode layer. This is because it may occur.

  On the other hand, when the organic thin-film solar cell of the present invention is a bulk heterojunction type, the thickness of the photoelectric conversion layer is not particularly limited as long as it is a thickness generally employed in the bulk heterojunction type. Specifically, it is preferably in the range of 0.2 nm to 3000 nm, and more preferably in the range of 10 nm to 600 nm. When the film thickness is thicker than the above range, the film resistance in the electron-hole transport layer may be increased. On the other hand, when the film thickness is thinner than the above range, the first electrode layer and the second electrode layer This is because a short circuit may occur.

  Further, the number of layers of the photoelectric conversion layer may be one layer or a plurality of layers.

2. Substrate Next, the substrate used in the present invention will be described. In the present invention, the substrate is not particularly limited, even if it is transparent or opaque. For example, when the substrate side is a light receiving surface, it is a transparent substrate. Is preferred. The transparent substrate is not particularly limited, and for example, a non-flexible transparent rigid material such as quartz glass, Pyrex (registered trademark), synthetic quartz plate, or a transparent resin film, an optical resin plate, etc. The transparent flexible material which has flexibility can be mentioned.

  In the present invention, among the above, the substrate is preferably a flexible material such as a transparent resin film. This is because the transparent resin film has excellent processability and is useful in manufacturing cost and weight reduction.

3. First Electrode Layer Next, the first electrode layer used in the present invention will be described. In the present invention, the first electrode layer is formed on the substrate.

The material for forming the first electrode layer is not particularly limited as long as it has conductivity. However, considering the irradiation direction of light, the work function of the material for forming the second electrode layer described later, and the like. It is preferable to select appropriately. For example, when the material for forming the second electrode layer is a material having a low work function, the material for forming the first electrode layer is preferably a material having a high work function. Examples of the material having a high work function include Au, Ag, Co, Ni, Pt, C, ITO, SnO ₂ , fluorine-doped SnO ₂ , and ZnO. Further, when the substrate of the bilayer type organic thin film solar cell is used as the light receiving surface, the first electrode layer is preferably a transparent electrode, and in this case, one generally used as a transparent electrode is used. Can do. Specifically, In—Zn—O (IZO), In—Sn—O (ITO), ZnO—Al, Zn—Sn—O, and the like can be given.

  The first electrode layer may be a single layer, or may be laminated using materials having different work functions.

  As the film thickness of the first electrode layer, in the case of the first electrode layer made of a single layer, the film thickness thereof is in the range of 0.1 to 500 nm in the case of being made of a plurality of layers. Especially, it is preferable that it exists in the range of 1 nm-300 nm. When the film thickness is smaller than the above range, the sheet resistance of the first electrode layer becomes too large, and the generated photocharge may not be sufficiently transmitted to the external circuit. This is because there is a possibility that the total light transmittance is lowered and the energy conversion efficiency is lowered.

  The first electrode layer may be formed on the entire surface of the substrate or may be formed in a pattern.

  Furthermore, the shape of the first electrode layer may be a flat shape, or may be an uneven shape such as a texture structure, a pyramid structure, a wave structure, a comb structure, or a nano pillow structure. For example, when the shape of the first electrode layer is uneven, incident light from the substrate side is scattered by the uneven shape of the first electrode layer, so that the photoelectric conversion layer can take in a large amount of light. Thereby, since light can be used effectively, energy conversion efficiency can be improved.

  In the present invention, when the substrate is a light receiving surface, the total light transmittance of the first electrode layer is preferably 85% or more, more preferably 90% or more, and particularly preferably 92% or more. This is because when the total light transmittance of the first electrode layer is within the above range, the first electrode layer can sufficiently transmit light, and the photoelectric conversion layer can absorb light efficiently. .

  In addition, the said total light transmittance is the value measured in the visible light area | region using the Suga Test Co., Ltd. total light transmittance apparatus (COLOUR S & M COMPUTER MODEL SM-C: model number).

  In the present invention, the sheet resistance of the first electrode layer is preferably 20Ω / □ or less, more preferably 10Ω / □ or less, and particularly preferably 5Ω / □ or less. This is because when the sheet resistance is larger than the above range, the generated photocharge may not be sufficiently transmitted to the external circuit.

  In addition, the said sheet resistance is measured based on JIS R1637 (Resistance test method of fine ceramics thin film: Measurement method by 4 probe method) using a surface resistance meter (Loresta MCP: Four-terminal probe) manufactured by Mitsubishi Chemical Corporation. It is the value.

4). Second Electrode Layer Next, the second electrode layer used in the present invention will be described. The second electrode layer in the present invention is an electrode that is formed on the photoelectric conversion layer and faces the first electrode layer.

  The material for forming the second electrode layer is not particularly limited as long as it has conductivity, but considering the irradiation direction of light, the work function of the material for forming the first electrode layer, and the like. It is preferable to select appropriately. For example, when the substrate is a light receiving surface, the first electrode layer is a transparent electrode. In such a case, the second electrode layer may not be transparent. In addition, when the first electrode layer is formed using a material having a high work function, the second electrode layer is preferably formed using a material having a low work function. , Li, In, Al, Ca, Mg, Sm, Tb, Yb, Zr, LiF, and the like.

  In addition, the second electrode layer may be a single layer or may be laminated using materials having different work functions.

  The film thickness of the second electrode layer is in the range of 0.1 nm to 500 nm when the second electrode layer is composed of a single layer, and in the case where the second electrode layer is composed of a plurality of layers, the total film thickness of each layer is combined. Among these, it is preferable to be in the range of 1 nm to 300 nm. When the film thickness is smaller than the above range, the sheet resistance of the second electrode layer becomes too large, and the generated photocharge may not be sufficiently transmitted to the external circuit. This is because the light transmittance is lowered and the light conversion efficiency may be lowered.

  Further, the second electrode layer may be formed on the entire surface of the photoelectric conversion layer or may be formed in a pattern.

  Furthermore, the shape of the second electrode layer may be a flat shape, or may be a concavo-convex shape such as a texture structure, a pyramid structure, a corrugated structure, a comb structure, or a nano pillow structure. For example, when the shape of the second electrode layer is uneven, incident light from the substrate side is irregularly reflected by the uneven shape of the second electrode layer, so that the photoelectric conversion layer can take in a large amount of light. Thereby, since light can be used effectively, energy conversion efficiency can be improved.

5. Others The layers that can constitute the organic thin film solar cell of the present invention will be described in addition to the above layers.

(1) Hole Extraction Layer In the present invention, for example, as shown in FIG. 2, a hole extraction layer 5 may be formed between the first electrode layer 2 and the photoelectric conversion layer 3.

  In the present invention, the hole extraction layer is a layer provided so that holes can be easily extracted from the photoelectric conversion layer to the first electrode layer. Thereby, since the hole extraction efficiency from the photoelectric conversion layer to the first electrode layer is increased, the energy conversion efficiency can be improved.

  The material used for such a hole extraction layer is not particularly limited as long as the material can stabilize the extraction of holes from the photoelectric conversion layer to the first electrode layer. Specifically, a conductive organic compound such as doped polyaniline, polyphenylene vinylene, polythiophene, polyethylenedioxythiophene (PEDOT), polypyrrole, polyparaphenylene, polyacetylene, triphenyldiamine (TPD), or tetrathiofulvalene, The organic material etc. which form the charge transfer complex which consists of electron-donating compounds, such as tetramethyl phenylenediamine, and electron-accepting compounds, such as tetracyano quinodimethane and tetracyanoethylene, can be mentioned. Also, a thin film of metal such as Au, In, Ag, Pd, etc. can be used. Furthermore, a thin film of metal or the like may be formed alone or in combination with the above organic material.

  In the present invention, among the above, polyethylene dioxythiophene (PEDOT), triphenyldiamine (TPD) and the like are particularly preferable.

  The thickness of the hole extraction layer is preferably in the range of 10 to 200 nm when the organic material is used, and in the range of 0.1 to 5 nm in the case of the metal thin film. It is preferable.

(2) Electron Extraction Layer In the present invention, for example, as shown in FIG. 2, an electron extraction layer 6 may be formed between the photoelectric conversion layer 3 and the second electrode layer 4.

  In the present invention, the electron extraction layer is a layer provided so that electrons can be easily extracted from the photoelectric conversion layer to the second electrode layer. Thereby, since the electron extraction efficiency from the photoelectric conversion layer to the second electrode layer is increased, the energy conversion efficiency can be improved.

  A material used for such an electron extraction layer is not particularly limited as long as it is a material that stabilizes extraction of electrons from the photoelectric conversion layer to the second electrode layer. Specifically, a conductive organic compound such as doped polyaniline, polyphenylene vinylene, polythiophene, polyethylenedioxythiophene (PEDOT), polypyrrole, polyparaphenylene, polyacetylene, triphenyldiamine (TPD), or tetrathiofulvalene, The organic material etc. which form the charge transfer complex which consists of electron-donating compounds, such as tetramethyl phenylenediamine, and electron-accepting compounds, such as tetracyano quinodimethane and tetracyanoethylene, can be mentioned. Moreover, the metal dope layer with an alkali metal or alkaline-earth metal is mentioned. Suitable materials include BCP (bathocuproin) or Bphen (bassophenantrone) and metal doped layers such as Li, Cs, Ba, Sr.

(3) Protective sheet In this invention, as shown in FIG. 2, the protective sheet 7 may be formed on the 2nd electrode layer 4, for example. In this invention, a protective sheet is a layer provided in order to protect the organic thin film solar cell of this invention from the external field.

  Materials used for such protective sheets include metal plates or metal foils such as aluminum, fluorine resin sheets, cyclic polyolefin resin sheets, polycarbonate resin sheets, poly (meth) acrylic resin sheets, polyamide resin sheets. , A polyester resin sheet, or a composite sheet obtained by laminating and laminating a weather resistant film and a barrier film.

  The thickness of the protective sheet is preferably in the range of 20 μm to 500 μm, more preferably in the range of 50 μm to 200 μm.

  Further, the protective sheet may have a barrier property as described in the column of a barrier layer described later.

  Furthermore, the design properties can be imparted to the protective sheet by coloring or the like. At this time, it may be colored by kneading the pigment into the protective sheet or the like, for example, by laminating a colored layer such as a blue hard coat layer.

(4) Filler layer In the present invention, a filler layer may be formed between the second electrode layer and the protective sheet. In this invention, a filler layer is a layer provided in order to adhere the back surface side of an organic thin film solar cell, ie, a 2nd electrode layer, and the said protective sheet, and to seal an organic thin film solar cell.

  As such a filler layer, what is generally used as a filler layer of a solar cell should just be mentioned, for example, ethylene-vinyl acetate copolymer resin is mentioned.

  Further, the thickness of the filler layer is preferably 50 μm to 2000 μm, and more preferably in the range of 200 μm to 800 μm. This is because when the thickness is less than the above range, the strength is reduced, and conversely, when the thickness is greater than the above range, cracks and the like are likely to occur.

(5) Barrier layer In the present invention, a barrier layer is formed between the surface of the substrate, between the substrate and the first electrode layer, between the surface of the protective sheet, or between the protective sheet and the second electrode layer. May be. Moreover, when the said board | substrate or the said protective sheet consists of multiple layers, you may provide a barrier layer between the multilayer substrate or protective sheet. The barrier layer used in the present invention is a transparent layer, and is a layer provided to prevent the entry of oxygen and water vapor from the outside and protect the organic thin film solar cell of the present invention. When the photoelectric conversion layer or the like is exposed to water vapor, oxygen, or the like, the deterioration thereof is promoted, resulting in a disadvantage that the battery life of the organic thin film solar cell is shortened. Therefore, the battery life is extended by providing a barrier layer that prevents permeation of water vapor and oxygen into the organic thin film solar cell.

  Although the formation position of the barrier layer used in the present invention is various as described above, it is preferable that the barrier layer is formed on both the substrate side and the protective sheet side. This is because entry of water vapor, oxygen, and the like can be sufficiently suppressed.

  Moreover, when the said protective sheet is a resin sheet, it is preferable that the barrier layer is formed between the protective sheet and the 2nd electrode layer. This is because when the organic thin film solar cell of the present invention is produced, gas is generated from the resin contained in the protective sheet, which may adversely affect the second electrode layer and the photoelectric conversion layer.

The barrier layer used in the present invention has an oxygen permeability of 5 cc / m ² · day or less, and preferably 10 ⁻¹ cc / m ² · day or less. The water vapor transmission rate is 1 g / m ² · day or less, and preferably 10 ⁻¹ g / m ² · day or less.

  Here, the oxygen permeability is measured under the conditions of 23 ° C. and 90% Rh using an oxygen gas permeability measuring device (manufactured by MOCON, OX-TRAN 2/20). The water vapor transmission rate was measured using a water vapor transmission rate measuring device (manufactured by MOCON, PERMATRAN-W 3/31) under conditions of 37.8 ° C. and 100% Rh.

  Such a barrier layer is not particularly limited as long as it has the above-described barrier properties, but it is preferable to have a vapor deposition layer formed by a vapor deposition method because of its high barrier properties. .

  The vapor deposition layer is not particularly limited as long as it is a layer formed by a vapor deposition method, and may be a CVD method or a PVD method. When the vapor deposition layer is formed by a CVD method such as a plasma CVD method, it is possible to form a dense and highly barrier layer. In the present invention, however, from the viewpoint of manufacturing efficiency and cost, etc. The PVD method is preferred. Examples of the PVD method used in the present invention include a vacuum vapor deposition method, a sputtering method, and an ion plating method. Among these, the vacuum vapor deposition method is preferable from the standpoint of barrier properties. Specific examples of the vacuum deposition method used in the present invention include a vacuum deposition method using an electron beam (EB) heating method, a vacuum deposition method using a high frequency dielectric heating method, and the like.

Further, the material for the vapor deposition layer is preferably a metal or an inorganic oxide, Ti, Al, Mg, Zr, silicon oxide, aluminum oxide, silicon oxynitride, aluminum oxynitride, magnesium oxide, zinc oxide, indium oxide, oxide Tin, yttrium oxide, B ₂ O ₃ , CaO and the like can be mentioned, and among these, silicon oxide is preferable. This is because the layer made of silicon oxide has high barrier properties and transparency.

  The thickness of the vapor deposition layer in the present invention is appropriately selected depending on the type and configuration of the material used, and is appropriately selected, but is preferably in the range of 10 nm to 500 nm. This is because if the thickness of the vapor deposition layer is thinner than the above range, it may be difficult to obtain a uniform layer and the barrier property may not be obtained. In addition, when the thickness of the vapor deposition layer is larger than the above range, the barrier property may be significantly impaired after the film formation due to a crack in the vapor deposition layer due to external factors such as pulling. In addition, it takes time to form and the productivity is also lowered.

(6) Antireflection layer In this invention, when the board | substrate side turns into a light-receiving surface, it is preferable that the antireflection layer is formed in the surface opposite to the surface in which the 1st electrode layer of the board | substrate is formed. By providing an antireflection layer, reflection of light incident from the substrate side can be prevented, and light incident on the organic thin film solar cell is increased, thereby improving the light absorption rate of the photoelectric conversion layer. This is because energy conversion efficiency can be improved.

The material of such an antireflection layer is not particularly limited as long as it can prevent reflection, and examples thereof include inorganic oxides. _{Specifically, TiO 2, SiO x, Al} 2 O 3, TiO , and the like.

  Further, the antireflection layer may be a single layer or may be a layer formed using a plurality of materials. Among these, a laminated antireflection layer is preferable.

  Examples of the method for forming the antireflection layer include vapor deposition methods such as a CVD method, a PVD method such as a vacuum deposition method, a sputtering method, and an ion plating method.

(7) Layer structure In the present invention, there is no particular limitation as long as a photoelectric conversion layer is disposed between the first electrode layer and the second electrode layer. For example, as described above, the photoelectric conversion layer may be provided not only as a single layer but also as a plurality of layers. When a plurality of photoelectric conversion layers are formed, a separate electrode layer is provided between the photoelectric conversion layers. It may be provided. Specifically, as shown in FIG. 3, the intermediate electrode layer 8 is separately formed between the two photoelectric conversion layers 3.

  Such an intermediate electrode layer is not particularly limited as long as it does not impair the charge separation function of the photoelectric conversion layer and is transparent. For example, a metal thin film can be used. Specifically, Ag etc. are mentioned.

  The film thickness of the intermediate electrode layer is preferably extremely thin so as not to impair the charge separation function of the photoelectric conversion layer. Specifically, it is preferably within a range of 0.01 nm to 10 nm, and more preferably within a range of 0.1 nm to 5 nm.

B. Next, the manufacturing method of the organic thin film solar cell of this invention is demonstrated.

  The method for producing an organic thin film solar cell of the present invention includes a first electrode layer forming step of forming a first electrode layer on a substrate, a photoelectric conversion layer forming step of forming a photoelectric conversion layer on the first electrode layer, A second electrode forming step of forming a second electrode layer, which is an electrode facing the first electrode layer, on the photoelectric conversion layer, wherein the photoelectric conversion layer forming step uses an ionic liquid as a medium. And a coating solution for forming a photoelectric conversion layer in which an organic semiconductor material is dissolved or dispersed is applied, and the ionic liquid is solidified.

  FIG. 4 is a process diagram showing an example of a method for producing an organic thin film solar cell of the present invention. In the method for producing an organic thin film solar cell of the present invention, first electrode layer 2 is first formed on substrate 1 as shown in FIG. 4A (first electrode layer forming step). Next, a photoelectric conversion layer forming coating solution 13 in which an organic semiconductor material is dissolved or dispersed is applied onto the first electrode layer 2 using an ionic liquid as a medium (FIG. 4B), and ultraviolet rays 11 are applied. Is applied to solidify the photoelectric conversion layer forming coating solution to form the photoelectric conversion layer 3 (FIG. 4C), and a photoelectric conversion layer forming step is performed. Furthermore, as shown in FIG.4 (d), a 2nd electrode layer is formed on this photoelectric converting layer 3 (2nd electrode layer formation process).

  According to the present invention, in the photoelectric conversion layer forming step, the ionic liquid used for the photoelectric conversion layer forming coating liquid can sufficiently dissolve or disperse the organic semiconductor material. In the photoelectric conversion layer formed using the conversion layer forming coating solution, it is possible to contain an organic semiconductor material sufficient to function as a photoelectric conversion layer.

  Also, unlike the conventional one in which a coating solution having an extremely small amount of organic semiconductor material dissolved is applied and a large amount of organic solvent is removed and solidified to form a film, in the present invention, a coating for forming a photoelectric conversion layer is used. Since the ionic liquid is solidified by light irradiation or heating after application of the working solution, the photoelectric conversion layer has good film surface smoothness and good dispersibility of the organic semiconductor material. Can be formed.

Furthermore, the ionic liquid used itself can function as an organic semiconductor in the photoelectric conversion layer. Thereby, an organic thin film solar cell with high energy conversion efficiency can be manufactured.
Hereinafter, each process of the manufacturing method of such an organic thin-film solar cell is demonstrated.

1. First Electrode Layer Forming Step In the method for manufacturing an organic thin film solar cell of the present invention, first, a first electrode layer forming step for forming a first electrode layer on a substrate is performed.

  For example, in FIG. 4A, the first electrode layer 2 is formed on the entire surface of the substrate 1, but in the present invention, the first electrode layer may be formed in a pattern.

  In addition, the shape of the first electrode layer may be a flat shape, or may be an uneven shape such as a texture structure, a pyramid structure, a wave shape structure, a comb structure, or a nano pillow structure. For example, when the shape of the first electrode layer is uneven, incident light from the substrate side is scattered by the uneven shape of the first electrode layer, so that the photoelectric conversion layer can take in a large amount of light. Thereby, since light can be used effectively, energy conversion efficiency can be improved.

  As a method for forming the first electrode layer, a general electrode forming method can be used. Specifically, a PVD method such as a vacuum deposition method, a sputtering method, an ion plating method, or a CVD method can be used. Examples thereof include a dry coating method and a wet coating method in which a coating liquid containing ITO fine particles is applied.

  The patterning method for forming the first electrode layer in a pattern is not particularly limited as long as it can accurately form the first electrode layer in a desired pattern. Lithographic methods and the like can be mentioned.

  Furthermore, examples of the method for forming the first electrode layer so as to have a concavo-convex structure include corona treatment, etching, and sand blasting. These methods may be used alone or in combination of a plurality of methods. Further, the concavo-convex structure can be formed in a self-organized manner by film formation conditions such as a CVD method and a sputtering method, or by surface treatment of the substrate.

  In addition, since it described in the column of the 1st electrode layer of "A. organic thin film solar cell" mentioned above about the formation material, film thickness, etc. of a 1st electrode layer, description here is abbreviate | omitted.

2. Photoelectric Conversion Layer Formation Step Next, the photoelectric conversion layer formation step will be described. In the method for producing an organic thin-film solar cell of the present invention, the photoelectric conversion layer forming step applies a coating liquid for forming a photoelectric conversion layer in which an organic semiconductor material is dissolved or dispersed using an ionic liquid as a medium, and the above ions This is done by solidifying the liquid.

  According to the present invention, a photoelectric conversion layer is formed using a coating liquid for forming a photoelectric conversion layer using an ionic liquid capable of sufficiently dissolving or dispersing an organic semiconductor material as a medium. It is possible to contain an organic semiconductor material sufficient to function as a photoelectric conversion layer. Also, unlike the conventional one in which a coating solution having an extremely small amount of organic semiconductor material dissolved is applied and a large amount of organic solvent is removed and solidified to form a film, in the present invention, a coating for forming a photoelectric conversion layer is used. Since the ionic liquid is solidified by light irradiation or heating after application of the working solution, the photoelectric conversion layer has good film surface smoothness and good dispersibility of the organic semiconductor material. Can be formed.

  Furthermore, when the organic thin-film solar cell produced by the present invention is a bulk heterojunction type, the photoelectric conversion layer is formed as an electron-hole transport layer having both electron donating and electron accepting functions as described above. The In this case, the coating liquid for forming a photoelectric conversion layer is prepared by dissolving or dispersing an organic semiconductor material having an electron donating property and an organic semiconductor material having an electron donating property in an ionic liquid. Conventionally, since the solubility or dispersibility of the organic semiconductor material in the solvent is low and the dispersibility of the organic semiconductor material in the photoelectric conversion layer is low, a pn junction is hardly formed and energy conversion efficiency is reduced. Has occurred. However, in the present invention, as described above, since the dispersibility of the organic semiconductor material in the photoelectric conversion layer is good, the pn junction is widely formed, so that the energy conversion efficiency can be improved.

  In the present invention, the photoelectric conversion layer forming step uses a ionic liquid as a medium, and a photoelectric conversion layer forming coating solution preparation step for preparing a photoelectric conversion layer forming coating solution in which an organic semiconductor material is dissolved or dispersed; It has an application | coating process which apply | coats the said coating liquid for photoelectric conversion layer formation on the said 1st electrode layer, and a solidification process which solidifies the said ionic liquid. In the following, each process will be described separately.

(1) Photoelectric conversion layer forming coating liquid preparation step In the photoelectric conversion layer forming step in the present invention, first, a photoelectric conversion layer forming coating solution in which an organic semiconductor material is dissolved or dispersed using an ionic liquid as a medium. The process for preparing a coating liquid for forming a photoelectric conversion layer is prepared.

  Since the ionic liquid and the organic semiconductor material are described in the column of the photoelectric conversion layer of “A. Organic thin film solar cell” described above, description thereof is omitted here.

  In the coating liquid for forming a photoelectric conversion layer used in the present invention, the mixing ratio of the ionic liquid and the organic semiconductor material is preferably adjusted appropriately to the optimal mixing ratio depending on the material used. Specifically, it is preferable that the weight ratio is within a range of 0.0001 to 1000 with respect to the organic semiconductor material 1, and particularly within a range of 0.01 to 10, and particularly within a range of 0.05 to 2. It is preferable.

  Moreover, in the solidification process mentioned later, when superposing | polymerizing an ionic liquid and solidifying, you may add a polymerization initiator to the coating liquid for photoelectric conversion layer formation as needed. In some cases, a polymerization initiator is not required, but in the case of polymerization by, for example, ultraviolet (UV) irradiation, which is generally used, a photopolymerization initiator is usually used to promote polymerization.

  As such a polymerization initiator, a photopolymerization initiator is used when the polymerizable group of the ionic liquid is photopolymerizable, and thermal polymerization is started when the polymerizable group of the ionic liquid is thermally polymerizable. An agent is used.

  As said photoinitiator, what is generally used as a photoinitiator can be used, It can use individually or in combination of 2 or more types. For example, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one (commercial product Irgacure 907 manufactured by Ciba Specialty Chemicals), 2-benzyl-2-dimethylamino-1- ( 4-morpholinophenyl) butanone-1 (commercially available Ciba Specialty Chemicals Irgacure 369), bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Ciba Specialty Chemicals trade name CGI819), 2,4 6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO manufactured by BASF), 2,4-trichloromethyl- (piprolonyl) -6-triazine (commercial product, product name Triazine PP manufactured by Nippon Sebel Hegner) and the like can be used.

  The thermal polymerization initiator is not particularly limited as long as it can generate a radical upon heating and polymerize a polymerizable group of an ionic liquid to form a film. Generally, as a radical polymerization initiator, What is used can be used. Specific examples include peroxide thermal polymerization initiators and azo thermal polymerization initiators. As the peroxide-based thermal polymerization initiator, cumyl peroxyneodecanate, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxyneodecanate, isobutyl peroxide, 3, 5 , 5-trimethylhexanol peroxide, lauryl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanate, t-hexylperoxy-2-ethylhexanate, benzoyl peroxide, t- Examples include butyl peroxymaleic acid and t-butyl peroxybenzoate. As the azo-based thermal polymerization initiator, 2,2′-azobis [2- (N-phenylamidino) propane] hydrochloride, 2,2′-azobis {2- [N- (4-chlorophenyl) amidino] Propane} hydrochloride, 2,2′-azobis {2- [N- (4-hydroxyphenyl) amidino] propane} hydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazoline-2- Yl) propane] hydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] hydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] Examples thereof include sulfate hydrates. These polymerization initiators may be used alone or in combination of two or more.

  The addition amount of the polymerization initiator is generally 0.01 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.2 to 2% by weight for forming a photoelectric conversion layer. It can be added to the coating solution.

(2) Application process In the photoelectric conversion layer formation process in this invention, the application process which apply | coats the said coating liquid for photoelectric conversion layer formation on the said 1st electrode layer is performed.

  The application method is not particularly limited as long as it can be uniformly formed to a predetermined film thickness. Specific examples include a die coating method, a spin coating method, a dip coating method, a roll coating method, a bead coating method, and a spray coating. Among these, a spin coating method or a die coating method is preferable. This is because the photoelectric conversion layer can be accurately formed with a predetermined thickness.

  In addition, about the film thickness etc. of the photoelectric converting layer, since it described in the column of the photoelectric converting layer of "A. organic thin film solar cell" mentioned above, description here is abbreviate | omitted.

(3) Solidification process In the photoelectric conversion layer formation process in this invention, the solidification process which solidifies the ionic liquid in the said coating liquid for photoelectric conversion layer formation is performed.

  As described above, as a method of solidifying the ionic liquid, (i) a method in which a host polymer is impregnated with an ionic liquid to form a gel electrolyte, and (ii) a polymer is formed by forming the ionic liquid. And (iii) a method of forming a polymer by fixing the ionic liquid itself to the main chain and the side chain.

  In the present invention, it is particularly preferable to solidify the ionic liquid by fixing the ionic liquid itself to the main chain and the side chain to form a polymer. This is because it is possible to form a film by polymerizing an ionic liquid, and it is possible to form a photoelectric conversion layer having excellent smoothness and dispersibility of the organic semiconductor material and having high film strength. . Hereinafter, a method for polymerizing an ionic liquid will be described.

  Examples of the method for polymerizing the ionic liquid include a method of irradiating actinic radiation and a method of heating. Moreover, as above-mentioned, the polymerization initiator may be contained in the coating liquid for photoelectric conversion layer formation as needed.

  The active radiation as used in the field of this invention means the active radiation which has the capability to raise | polymerize with respect to the polymeric group contained in an ionic liquid.

  The actinic radiation is not particularly limited as long as it is an actinic radiation capable of polymerizing an ionic liquid, but usually ultraviolet light or visible light is used from the viewpoint of the ease of the apparatus. Among these, a method of irradiating ultraviolet rays (UV) as active radiation is a preferable method. This is because the method using UV as the actinic radiation is an already established technique, and therefore it is easy to apply to the present invention including the photopolymerization initiator to be used.

  As the light source of this irradiation light, low pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), high pressure discharge lamp (high pressure mercury lamp, metal halide lamp), short arc discharge lamp (super high pressure mercury lamp, xenon lamp, mercury xenon) Lamp). In particular, the use of metal halide lamps, xenon lamps, high-pressure mercury lamps, etc. is recommended.

  Irradiation intensity is appropriately adjusted according to the type of ionic liquid and the amount of photopolymerization initiator.

  On the other hand, as a heating method among the methods for polymerizing the ionic liquid, for example, a method of passing or standing in a device that heats the entire specific space such as an oven, a method of applying hot air, or far infrared rays A direct heating method or the like can be used.

  In addition, the heating temperature at this time is generally in the range of 30 ° C to 300 ° C, preferably 40 ° C to 150 ° C, more preferably 50 ° C to 100 ° C.

  As described above, the method of forming a film by dissolving or dispersing an organic semiconductor material using an ionic liquid as a medium can be used not only for a photoelectric conversion layer in an organic thin film solar cell but also for an organic EL, an organic transistor, and the like. .

3. Second Electrode Formation Step Next, the second electrode layer formation step will be described. In the present invention, the second electrode layer forming step is a step of forming the second electrode layer on the photoelectric conversion layer.

  For example, in FIG. 4D, the second electrode layer 4 is formed on the entire surface of the photoelectric conversion layer 3, but in the present invention, the second electrode layer may be formed in a pattern.

  In addition, the shape of the second electrode layer may be a flat shape, or may be an uneven shape such as a texture structure, a pyramid structure, a wave shape structure, a comb structure, or a nano pillow structure. For example, when the shape of the first electrode layer is uneven, incident light from the substrate side is irregularly reflected by the uneven shape of the second electrode layer, so that the photoelectric conversion layer can take in a large amount of light. Thereby, since light can be used effectively, energy conversion efficiency can be improved.

  As a method for forming such a second electrode layer, a generally used method can be used, for example, a PVD method such as a vacuum deposition method, a sputtering method, an ion plating method, or a dry coating method such as a CVD method. And a wet coating method in which a metal paste containing a metal colloid such as Ag is used.

  The patterning method for forming the second electrode layer in a pattern is not particularly limited as long as the second electrode layer can be accurately formed in a desired pattern. Lithographic methods and the like can be mentioned.

  Furthermore, examples of the method for forming the second electrode layer so as to have a concavo-convex structure include corona treatment, etching, and sand blasting. These methods may be used alone or in combination of a plurality of methods. Further, the concavo-convex structure can be formed in a self-organized manner by film formation conditions such as a CVD method and a sputtering method, or by surface treatment of the substrate.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
[Example 1]
(Formation of first electrode layer)
First, a barrier layer made of SiO ₂ is formed on the surface of the super-barrier film substrate, and an ITO film (film thickness: 150 nm, sheet resistance: 15 Ω / □) as a transparent electrode is formed on the barrier layer by the IP method. And patterned. Next, the substrate on which the ITO film was formed was cleaned using acetone, a substrate cleaning solution, and IPA to form a first electrode layer.

(Formation of hole extraction layer)
On the first electrode layer, PEDOT: PSS (poly (3,4) -ethylenedioxythiophene / polystyrene sulfonate aqueous dispersion) was spin-coated and dried at 150 ° C. for 30 minutes to obtain a positive film having a thickness of 40 nm. A hole removal layer was formed.

(Formation of photoelectric conversion layer)
A weight ratio of polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)), polyfluorene derivative, and nanotubes in a chloroform solvent is 10: 20: 1, and the concentration is 0.00. An ionic liquid having a polymerizable group (vinyl group) in the side chain represented by the following chemical formula I and a polymerization initiator are added to this solution and stirred, and the supernatant of this solution is added. The liquid was filtered with φ0.2 μm filter paper to prepare a coating liquid. Next, this coating solution was spin-coated on the hole extraction layer and dried and cured at 110 ° C. for 2 hours to form a photoelectric conversion layer having a thickness of 50 nm.

(Formation of second electrode layer)
A second electrode layer is formed on the photoelectric conversion layer by depositing Ca to a thickness of 100 nm by a vapor deposition method, and further depositing Al thereon by a vapor deposition method to a thickness of 500 nm. Formed.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bulk heterojunction type organic thin film solar cell.

[Example 2]
A barrier layer, a first electrode layer, and a hole extraction layer were formed in the same manner as in Example 1 except that a glass substrate was used instead of the super-barrier film substrate.

(Formation of photoelectric conversion layer)
A polythiophene derivative (P3HT: poly-3-hexylthiophene-2,5-diyl (resiregular)) is dissolved in a chloroform solvent to a concentration of 0.1% by weight, and this solution is represented by the above chemical formula I. An ionic liquid having a polymerizable group (vinyl group) in the side chain and a polymerization initiator were added and stirred, and the supernatant of this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole extraction layer and dried and cured at 110 ° C. for 2 hours to form a hole transport layer having a thickness of 30 nm.

  Next, the polyfluorene derivative is dissolved in a xylene solvent so as to have a concentration of 0.3% by weight, and this solution contains an ionic liquid having a polymerizable group (vinyl group) in the side chain represented by the above chemical formula I. Then, the polymerization initiator was added and stirred, and the supernatant of this solution was filtered with a filter paper of φ0.2 μm to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried and cured at 110 ° C. for 2 hours to form an electron transport layer having a thickness of 30 nm.

(Formation of second electrode layer)
A second electrode layer was formed on the photoelectric conversion layer by depositing Al so as to have a thickness of 500 nm by an evaporation method.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 3]
(Formation of first electrode layer)
A barrier layer made of SiO ₂ is formed on the surface of the super-barrier film substrate, and a SnO ₂ film (film thickness: 150 nm, sheet resistance: 15 Ω / □), which is a transparent electrode, is formed on the barrier layer by a CVD method. Patterned. Next, the substrate on which the SnO ₂ film was formed was cleaned using acetone, a substrate cleaning solution, and IPA, thereby forming a first electrode layer.

(Formation of photoelectric conversion layer)
A polyphenylene vinylene (PPV) derivative is dissolved in a chloroform solvent to a concentration of 0.5% by weight, and this solution has an ionic liquid having a polymerizable group (acrylic group) in the side chain represented by the following chemical formula II. Then, the polymerization initiator was added and stirred, and the supernatant of this solution was filtered with a filter paper of φ0.2 μm to prepare a coating solution. This coating solution was spin-coated on the first electrode layer and dried and cured at 110 ° C. for 2 hours to form a hole transport layer having a thickness of 30 nm.

  Next, a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyric acid methyl ester) was dissolved in a chloroform solvent to a concentration of 0.1% by weight. An ionic liquid having a polymerizable group (acrylic group) in the indicated side chain and a polymerization initiator were added and stirred, and the supernatant of this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. . This coating solution was spin-coated on the hole transport layer and dried and cured at 110 ° C. for 2 hours to form an electron transport layer having a thickness of 30 nm.

(Formation of second electrode layer)
On the electron-hole transport layer, LiF was deposited to a thickness of 1 nm by a vapor deposition method, and further Al was deposited to a thickness of 50 nm by a vapor deposition method. An electrode layer was formed.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 4]
A barrier layer, a first electrode layer, and a hole extraction layer were formed in the same manner as in Example 1 except that a glass substrate was used instead of the super-barrier film substrate.

(Formation of photoelectric conversion layer)
A hole transport layer was formed in the same manner as in Example 2.
Next, a polyfluorene derivative and a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyric acid methyl ester) are mixed in a chloroform solvent at a weight ratio of 1: 1 and a concentration of 0.3% by weight. To this solution, an ionic liquid having a polymerizable group (vinyl group) in the side chain represented by the above chemical formula I and a polymerization initiator are added and stirred, and the supernatant of this solution is φ0. A coating solution was prepared by filtering with 2 μm filter paper. This coating solution was spin-coated on the hole transport layer and dried and cured at 110 ° C. for 2 hours to form an electron transport layer having a thickness of 30 nm.

(Formation of second electrode layer)
A second electrode layer was formed in the same manner as in Example 1.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 5]
In the same manner as in Example 1, a barrier layer, a first electrode layer, and a hole extraction layer were formed.

(Formation of photoelectric conversion layer)
A hole transport layer was formed in the same manner as in Example 2 except that an ionic liquid having a polymerizable group (acrylic group) in the side chain represented by the above chemical formula II was used.
Next, the polyfluorene derivative and the nanotube are dissolved in a chloroform solvent so that the weight ratio is 5: 1 and the concentration is 0.3% by weight, and the side chain represented by the above chemical formula II is added to this solution. An ionic liquid having a polymerizable group (acrylic group) and a polymerization initiator were added and stirred, and the supernatant of this solution was filtered with a 0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried and cured at 110 ° C. for 2 hours to form an electron transport layer having a thickness of 30 nm.

(Formation of second electrode layer)
A second electrode layer was formed in the same manner as in Example 3.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 6]
A barrier layer and a first electrode layer were formed in the same manner as in Example 3 except that a glass substrate was used instead of the super-barrier film substrate. Further, a hole extraction layer was formed in the same manner as in Example 1.

(Formation of photoelectric conversion layer)
A hole transport layer was formed in the same manner as in Example 2.
Next, a polyphenylene vinylene (PPV) derivative and a fullerene derivative (PCBM: [6,6] -phenyl-C61 butyric acid methyl ester) in a chloroform solvent have a weight ratio of 1: 1 and a concentration of 0.3. An ionic liquid having a polymerizable group (vinyl group) in the side chain represented by the above chemical formula I and a polymerization initiator are added to this solution and stirred, and the supernatant of this solution is stirred. Was filtered with φ0.2 μm filter paper to prepare a coating solution. This coating solution was spin-coated on the hole transport layer and dried and cured at 110 ° C. for 2 hours to form an electron transport layer having a thickness of 30 nm.

(Formation of second electrode layer)
A second electrode layer was formed in the same manner as in Example 1.

  Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 7]
A barrier layer and a first electrode layer were formed in the same manner as in Example 1, and a hole transport layer was formed in the same manner as in Example 3. Furthermore, an electron transport layer was formed in the same manner as in Example 4 except that an ionic liquid having a polymerizable group (acrylic group) in the side chain represented by the above chemical formula II was used. Then, the second electrode layer was formed in the same manner as in Example 3. Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bilayer type organic thin film solar cell.

[Example 8]
A barrier layer, a first electrode layer, and a hole extraction layer were formed in the same manner as in Example 1 except that a glass substrate was used instead of the super-barrier film substrate. Further, a photoelectric conversion layer was formed in the same manner as in Example 1 except that an ionic liquid having a polymerizable group (acrylic group) in the side chain represented by the above chemical formula II was used. Then, the second electrode layer was formed in the same manner as in Example 2. Finally, it was sealed from the second electrode layer side with a protective sheet and an adhesive sealing material to produce a bulk heterojunction type organic thin film solar cell.

[Comparative Example 1]
A bilayer organic thin film solar cell was produced in the same manner as in Example 4 except that the ionic liquid was not used.

[Evaluation]
Regarding the solar cell characteristics, AM1.5 and simulated sunlight (100 mW / cm ² ) were used as irradiation light sources, and current-voltage characteristics were evaluated by applying voltage with a source measure unit (HP4100, manufactured by HP). The evaluation results are shown in Table 1 below. The evaluation result showed energy conversion efficiency η (%).

It is a schematic sectional drawing which shows an example of the organic thin film solar cell of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell of this invention. It is process drawing which shows an example of the manufacturing method of the organic thin film solar cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... 1st electrode layer 3 ... Photoelectric conversion layer 4 ... 2nd electrode layer

Claims (5)

A substrate, a first electrode layer formed on the substrate, a photoelectric conversion layer formed on the first electrode layer, and an electrode formed on the photoelectric conversion layer and facing the first electrode layer. An organic thin film solar cell having a second electrode layer,
The said photoelectric converting layer contains the electroconductive compound formed by solidifying an ionic liquid, and an organic-semiconductor material, The organic thin film solar cell characterized by the above-mentioned.   2. The organic thin film solar cell according to claim 1, wherein the ionic liquid is an imidazolium salt.   The organic thin film solar cell according to claim 1, wherein the ionic liquid has a polymerizable group. The ionic liquid has the general formula (1)

(Wherein, X ^- is ^{Br -,} PF ₆ - or ^{_{(CF 3 SO 2) 2 N}} - (TFSI -) represents one of, n represents represents 1-100.) Is a compound represented by The organic thin-film solar cell of Claim 2 or Claim 3 characterized by these. A first electrode layer forming step of forming a first electrode layer on the substrate; a photoelectric conversion layer forming step of forming a photoelectric conversion layer on the first electrode layer; and the first electrode layer on the photoelectric conversion layer. And a second electrode forming step of forming a second electrode layer that is an electrode facing the organic thin film solar cell,
The photoelectric conversion layer forming step is performed by applying a photoelectric conversion layer forming coating solution in which an organic semiconductor material is dissolved or dispersed using an ionic liquid as a medium, and solidifying the ionic liquid. A method for producing an organic thin-film solar cell.

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