JP2014011331A - Method of manufacturing organic thin-film solar cell - Google Patents

Abstract

An object of the present invention is to provide a method for producing an organic thin-film solar cell capable of increasing the temperature in the heating step and improving the production rate.
In a method for producing an organic thin-film solar cell having a coating step in which a layer is formed on a substrate by coating, the laminate after the coating step is heated to a temperature higher than the glass transition temperature Tg-50 ° C of the substrate. The above-mentioned problem is solved by including a heating step of heating the substrate and setting the residual elongation of the base material to 1.5% or less.
[Selection] Figure 1

Description

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

Conventionally, a method for producing a photoelectric conversion layer or an electrode constituting a solar cell element by coating is known. Moreover, the solar cell element using the resin base material is also known (for example, nonpatent literature 1).
On the other hand, when heating is required in the manufacturing process of the solar cell element, it is known that the film-like resin base material is elongated by heating, and thus the treatment is performed at a temperature sufficiently lower than the glass transition temperature Tg. For example, Patent Documents 1 and 2 describe that in the case of a resin film support having a low glass transition point Tg of the support, the support is likely to be uneven in a drying process at a high temperature.

JP 2001-113216 A JP 2011-181892 A

F. C. Krebs, Sol. Energy Mater. Sol. Cells, 2009, 93, 394-412.

  When forming the layer which comprises an organic solar cell on a film-form resin base material by application | coating, in order to raise a production rate, the heating process aiming at the removal of a solvent etc. is needed. Also, a heating process at a certain high temperature is important in order to improve the adhesion of the active layer. However, as described in Patent Documents 1 and 2, adverse effects such as deformation of the organic solar cell and damage to the elements occur due to heating, so the temperature cannot be raised so much and the production speed can be increased. could not.

  This invention solves the above problems, and makes it a subject to provide the manufacturing method of the organic thin film solar cell which can raise the temperature in a heating process and can improve a production rate.

Thus, as a result of studying a method for improving the production rate, the present inventors have found that a solar cell can be manufactured even if a heat treatment is performed at a temperature higher than conventionally considered by satisfying specific conditions. It was.
As a result of further earnest research, the inventors of the present invention at least in a method for producing an organic thin-film solar cell having a coating step of forming a layer on a substrate by coating the laminate after the coating step with a glass of a substrate. It has been found that the above problem can be solved by including a heating step of heating to a temperature higher than the transition temperature Tg-50 ° C., and making the residual elongation of the substrate 1.5% or less, and the present invention has been completed. The outline of the present invention is as follows.

The present invention provides a method for producing an organic thin-film solar cell having a coating step in which a layer is formed by coating on at least a base material. And a heating step of heating the substrate, wherein the residual elongation of the substrate is 1.5% or less.

Moreover, it is preferable that the said base material is resin, and it is preferable that this resin is transparent.
Moreover, it is preferable to perform the manufacturing method of this invention by roll toe roll.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing process of the organic thin film solar cell which can perform a heating process at temperature higher than the temperature considered conventionally and can improve a production rate can be provided.
In addition, heating at a high temperature can promote the formation of the nanostructure of the active layer, and as a result, the photoelectric conversion efficiency is improved. In addition, damage to the organic layer due to residual elongation of the substrate, for example, generation of cracks can be prevented.

It is a conceptual diagram which shows the one aspect | mode of a photoelectric conversion element. It is a schematic diagram showing the layer structure of the solar cell module using an organic thin film solar cell element. It is a schematic diagram showing the layer structure of the solar cell module using an organic thin film solar cell element.

  Hereinafter, the present invention will be described in detail while showing specific embodiments, but it is needless to say that the present invention is not limited to the illustrated specific embodiments.

<1. Application process>
The manufacturing method of the organic thin-film solar cell of this invention includes the application | coating process which forms a layer by application | coating at least on a base material. The application step is a case where at least one or more of an anode formation step, a cathode formation step, an active layer formation step, an electron extraction layer formation step, and a hole extraction layer formation step, which will be described later, is performed by application. Means the process. Application will be described in each forming step.

<2. Heating process>
In this invention, the heating process which heats the laminated body after an application | coating process to temperature higher than the glass transition temperature Tg-50 degreeC of a base material is characterized. By heating to such a temperature, the adhesiveness of the active layer can be increased, nanostructure formation can be promoted, and the solvent used for coating can be dried in a short time. The temperature of the heating step is higher than the glass transition temperature Tg-50 ° C of the substrate, preferably higher than the glass transition temperature Tg-45 ° C, more preferably higher than the glass transition temperature Tg-40 ° C. preferable. The upper limit of the temperature of the heating step is not particularly limited and may be a temperature exceeding the glass transition temperature Tg of the substrate, preferably the glass transition temperature Tg of the substrate + 100 ° C. or less, more preferably the glass transition temperature Tg or less of the substrate, It is particularly preferable that the temperature is lower than the glass transition temperature Tg of the substrate. The heating step is preferably performed after the coating step. In the case where a plurality of coating processes are generated in the production of the solar cell, the heating process may be performed every time each coating process is performed, or may be performed after all the coating processes are performed. The heating step may be performed a plurality of times, for example, twice after the formation of the active layer and after the formation step of the upper electrode.

  The time for the heating step is usually 1 minute or longer, preferably 3 minutes or longer, and usually 60 minutes or shorter, preferably 10 minutes or shorter. It is preferable that the heating step be completed at a time when the removal of the solvent is completed and the open circuit voltage, the short circuit current, and the fill factor, which are parameters of the solar cell performance, become constant values. The heating step may be performed in an air atmosphere, but is preferably performed under normal pressure and in an inert gas atmosphere.

As a heating method, the photoelectric conversion element may be placed on a heat source such as a hot plate, or the photoelectric conversion element may be placed in a heating atmosphere such as an oven or heating air. Moreover, although heating may be performed by a batch type or a continuous method, continuous methods, such as a roll toe roll, are preferable.

<3. Photoelectric Conversion Element (Organic Solar Cell Element)>
The photoelectric conversion element is a laminate having at least a pair of electrodes, an organic active layer that exists between the electrodes, and an electron extraction layer that exists between the organic active layer and one of the electrodes. FIG. 1 shows one embodiment of a photoelectric conversion element. The photoelectric conversion element shown in FIG. 1 is a photoelectric conversion element used in a general organic thin film solar cell, but the photoelectric conversion element according to the present invention is not limited to that shown in FIG. The photoelectric conversion element 107 includes a base 106, a cathode 101, an electron extraction layer 102, an active layer 103 (a layer containing a p-type semiconductor compound and an n-type semiconductor material), a hole extraction layer 104, and an anode 105, which are sequentially stacked. Can be manufactured.

[3-1. Substrate (106)]
The photoelectric conversion element 107 includes a base material 106 that serves as a support. That is, the electrodes 101 and 105 and the active layer 103 are formed on the substrate. In addition, an electron extraction layer 102 is formed between the cathode 101 and the active layer 103.

  The base material used in the production method of the present invention includes inorganic materials such as quartz, glass, sapphire and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, and ethylene vinyl alcohol. Polymers, fluororesin films, polyolefins such as vinyl chloride or polyethylene; organic materials such as cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene, or epoxy resins; paper such as paper or synthetic paper Materials: Examples include composite materials such as those in which a metal such as stainless steel, titanium, or aluminum is coated or laminated on the surface in order to impart insulating properties. Irumu is preferable. Such a resin is preferably transparent.

  Examples of the glass include soda glass, blue plate glass, and non-alkali glass. Among these, alkali-free glass is preferable in that there are few eluted ions from the glass.

  There is no restriction | limiting in the shape of a base material, For example, things, such as plate shape, a film form, or a sheet form, can be used. Moreover, although there is no restriction | limiting in the film thickness of a base material, Usually, it is 5 micrometers or more, Preferably it is 20 micrometers or more, On the other hand, it is 20 mm or less normally, Preferably it is 10 mm or less. It is preferable that the thickness of the substrate is 5 μm or more because the possibility that the strength of the photoelectric conversion element is insufficient is reduced. It is preferable that the thickness of the substrate is 20 mm or less because the cost is suppressed and the weight does not increase. When the material of the base material is glass, the film thickness is usually 0.01 mm or more, preferably 0.1 mm or more, and is usually 1 cm or less, preferably 0.5 cm or less. It is preferable that the glass substrate has a film thickness of 0.01 mm or more because the mechanical strength increases and it is difficult to break. Moreover, it is preferable that the film thickness of the glass substrate 106 is 0.5 cm or less because the weight does not increase.

  In the production method of the present invention, the residual elongation of the substrate is 3% or less, preferably 1.5% or less. By suppressing the residual elongation rate of the base material to 1.5% or less, damage to the organic layer can be prevented. The residual elongation rate of the base material indicates the rate at which the base material is extended in the entire manufacturing process of the solar cell. In particular, when the base material is extended by the heating process, the length in the extension direction of the base material before extension is shown. It refers to the ratio of the stretched length to the thickness.

In the present invention, a base material having a high glass transition temperature (Tg), specifically, a glass transition temperature (Tg) of 50 ° C. or higher, preferably 100 ° C. or higher, in order to make the residual elongation rate 1.5% or less. It is preferable to use a substrate. If the glass transition temperature is high, the heating process can be sufficiently performed at a higher temperature, so that the residual elongation can be suppressed to 1.5% or less. The glass transition temperature Tg can be measured by DSC measurement. The DSC measurement will be described later.
Examples of such a preferable substrate include polyethylene naphthalate (PEN) and polyimide (PI).

In order to suppress the residual elongation of the substrate to 1.5% or less, it is preferable to use a substrate having a high storage elastic modulus and a low loss elastic modulus in an environment of Tg-50 ° C. For example, it is preferable to use a base material having a value of loss elastic modulus G ″ / storage elastic modulus G ′ of 0.5 or less, preferably 0.2 or less. Storage elastic modulus G ′ and loss elastic modulus G ″. Can be measured using, for example, a viscoelasticity measuring device (a dynamic viscoelasticity measuring device manufactured by TA Instruments Japan).
Preferable base materials exhibiting such values under an environment of Tg-50 ° C. include polyethylene naphthalate (PEN) and polyimide (PI). Further, a material having such properties may be laminated on the base material.

Moreover, in order to suppress the residual elongation rate of the substrate to 1.5% or less, the linear expansion coefficient of the substrate at −30 to 30 ° C. is preferably 200 ppm / K or less, more preferably 100 ppm / K or less. Especially preferably, it is 50 ppm / K or less. The linear expansion coefficient is measured by, for example, ASTM D696. By setting the linear expansion coefficient to 50 ppm / K or less, deformation due to temperature change is reduced, and the residual elongation of the substrate can be suppressed.
Examples of such a preferable substrate include polyethylene naphthalate (PEN) and polyimide (PI).

As a method for suppressing the residual elongation rate of the base material to 1.5% or less, the tensile stress in the heating process is reduced, the temperature of the heating process is lowered, the time of the heating process is shortened, and the manufacturing is performed in a dry environment. In addition, after the heating step, the tensile stress is lowered to cool slowly.

As a method for reducing the tensile stress in the heating step, a method for physically supporting the base material in the heating step so that no stress is applied can be mentioned. For example, as will be described later, if the production method of the present invention is performed by a roll-to-roll method, when transporting the substrate fed from the roll, such as a suction roller or a conveyor that can support the substrate A method of reducing the tensile stress using a support is mentioned. It is preferable to suppress the tensile stress to 3 N / mm ² or less.

As a method for lowering the temperature of the heating step, for example, a method of controlling the temperature so as not to exceed the glass transition temperature Tg in the temperature range of the heating step described above can be mentioned.
As a method of shortening the time of the heating step, there is a method of shortening the heating time of the above-described heating step to prevent occurrence of elongation of the base material.

As an example of a dry environment when manufacturing in a dry environment, an atmosphere having a dew point temperature of −30 ° C. or lower can be given. In such an environment, expansion of the base material due to moisture absorption can be prevented, and the residual elongation rate of the base material can be suppressed to 1.5% or less. The dew point temperature is an index representing the amount of moisture in the atmosphere, and the dew point temperature is a temperature at which condensation starts when air containing water vapor is cooled. The dew point temperature can be obtained by directly measuring with a dew point thermometer or by obtaining a water vapor pressure from the temperature and relative humidity and obtaining a temperature at which the water vapor pressure is a saturated water vapor pressure. When the relative humidity is 100%, the current temperature becomes the dew point temperature as it is.

As a method of lowering the tensile stress after the heating step and slowly cooling, a method of reducing the tensile stress after the heating step and cooling to room temperature at a cooling rate of about 10 ° C./s, for example, can be given. By such slow cooling, rapid shrinkage of the base material can be prevented, and the residual elongation rate of the base material can be suppressed to 1.5% or less.

[3-2. Electrode (101, 105)]
The electrodes 101 and 105 have a function of collecting holes and electrons generated by light absorption. Therefore, the pair of electrodes may include an electrode 105 suitable for collecting holes (hereinafter also referred to as an anode) and an electrode 101 suitable for collecting electrons (hereinafter referred to as a cathode). ) Are preferably used. Any one of the pair of electrodes may be translucent, and both may be translucent. Translucency means that sunlight passes through 40% or more. Moreover, it is preferable that the sunlight transmittance of the transparent electrode is 70% or more in order to allow light to reach the active layer 103 through the transparent electrode. The light transmittance can be measured with a normal spectrophotometer.

(Anode formation process)
The manufacturing process of the organic thin film solar cell includes a process of forming the anode 105.
The anode 105 is an electrode generally made of a conductive material having a work function higher than that of the cathode and having a function of smoothly extracting holes generated in the active layer 103.

  Examples of the material of the anode 105 include conductive metal oxides such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide, indium oxide, and zinc oxide. A metal such as gold, platinum, silver, chromium or cobalt, or an alloy thereof; These substances are preferable because they have a high work function, and further, a conductive polymer material represented by PEDOT: PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid can be stacked. When laminating such a conductive polymer, the work function of this conductive polymer material is high, so even if it is not a material with a high work function as described above, it is suitable for cathodes such as Al and Mg. Metals can also be widely used. PEDOT: PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid, or a conductive polymer material in which polypyrrole, polyaniline, or the like is doped with iodine or the like can also be used as an anode material. When the anode 105 is a transparent electrode, it is preferable to use a light-transmitting conductive metal oxide such as ITO, zinc oxide, or tin oxide, and ITO is particularly preferable.

  The film thickness of the anode 105 is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, and more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the film thickness of the anode 105 is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the anode 105 is 10 μm or less, light can be efficiently converted into electricity without decreasing the light transmittance. it can. When the anode 105 is a transparent electrode, it is necessary to select a film thickness that can achieve both light transmittance and sheet resistance.

  The sheet resistance of the anode 105 is not particularly limited, but is usually 1Ω / □ or more, on the other hand, 1000Ω / □ or less, preferably 500Ω / □ or less, more preferably 100Ω / □ or less.

  As a method for forming the anode 105, a vacuum film forming method such as an evaporation method or a sputtering method can be given. Moreover, when forming by application | coating, the wet application method and the electrostatic spray coating method which apply | coat the ink containing a nanoparticle and a precursor and form a film | membrane are mentioned.

(Cathode formation process)
The manufacturing process of the organic thin film solar cell includes a step of forming a cathode.
The cathode 101 is generally an electrode made of a conductive material having a work function lower than that of the anode and having a function of smoothly extracting electrons generated in the active layer 103. The cathode 101 is adjacent to the electron extraction layer 102.

  Examples of the material of the cathode 101 include metals such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium, and magnesium, and alloys thereof; Examples include inorganic salts such as lithium and cesium fluoride; metal oxides such as nickel oxide, aluminum oxide, lithium oxide, and cesium oxide. These materials are preferable because they are materials having a low work function. Similarly to the anode 105, the cathode 101 can be made of a material having a high work function by using an n-type semiconductor such as titania having conductivity as the electron extraction layer 102. From the viewpoint of electrode protection, the material of the cathode 101 is preferably a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium, or an alloy using these metals such as indium tin oxide. .

  The film thickness of the cathode 101 is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the film thickness of the cathode 101 is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the cathode 101 is 10 μm or less, light can be efficiently converted into electricity without decreasing the light transmittance. it can. When the cathode 101 is a transparent electrode, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance.

  The sheet resistance of the cathode 101 is not particularly limited, but is usually 1000Ω / □ or less, preferably 500Ω / □ or less, and more preferably 100Ω / □ or less. Although there is no restriction on the lower limit, it is usually 1Ω / □ or more.

  Examples of a method for forming the cathode 101 include vacuum film formation methods such as vapor deposition and sputtering. Moreover, when forming by application | coating, the wet application method and the electrostatic spray coating method which apply | coat the ink containing a nanoparticle and a precursor and form a film | membrane are mentioned.

  Furthermore, the anode 105 and the cathode 101 may have a laminated structure of two or more layers. In addition, characteristics (electric characteristics, wetting characteristics, etc.) may be improved by performing surface treatment on the anode 105 and the cathode 101.

(Heating process)
After the anode 105 and the cathode 101 are stacked, the above-described heating process can be performed (this process may be referred to as an annealing process). By performing the heating step at the above temperature, an effect of improving the adhesion between the layers of the photoelectric conversion element, for example, the adhesion between the electron extraction layer 102 and the cathode 101 and / or the electron extraction layer 102 and the active layer 103 is obtained. ,preferable. By improving the adhesion between the layers, the thermal stability and durability of the photoelectric conversion element can be improved. If the temperature of the heating step is lower than the glass transition temperature Tg-50 ° C. of the substrate, the adhesion between the layers may be insufficient. In the heating step, stepwise heating may be performed within the above temperature range. Even when heat treatment is performed after the active layer formation step or the hole extraction layer formation step, the heat treatment may be performed after the anode 105 formation step.

  The time for the heating step is as described above. The heating process is preferably terminated when the open circuit voltage, short circuit current, and fill factor, which are parameters of the solar cell performance, reach a certain value. Moreover, it is preferable to implement a heating process under a normal pressure and inert gas atmosphere. The heating method is also as described above.

[3-3. Formation process of buffer layer (electron extraction layer 102, hole extraction layer 104)]
The manufacturing process of the organic thin film solar cell includes an electron extracting layer forming step and a hole extracting layer forming step. In FIG. 1, the photoelectric conversion element 107 includes an electron extraction layer 102 between the cathode 101 and the active layer 103. In addition, the photoelectric conversion element 107 includes a hole extraction layer 104 between the active layer 103 and the anode 105. The step of forming the electron extraction layer and the hole extraction layer 104 is not essential.

  The electron extraction layer 102 and the hole extraction layer 104 are preferably disposed so as to sandwich the active layer 103 between the pair of electrodes (101, 105). That is, when the photoelectric conversion element 107 includes both the electron extraction layer 102 and the hole extraction layer 104, the electrode 105, the hole extraction layer 104, the active layer 103, the electron extraction layer 102, and the electrode 101 are arranged in this order. Can do. When the photoelectric conversion element 107 includes the electron extraction layer 102 but does not include the hole extraction layer 104, the electrode 105, the active layer 103, the electron extraction layer 102, and the electrode 101 can be arranged in this order. The stacking order of the electron extraction layer 102 and the hole extraction layer 104 may be reversed, or at least one of the electron extraction layer 102 and the hole extraction layer 104 may be formed of a plurality of different films.

[3-3-1. Electron extraction layer (102)]
The material of the electron extraction layer 102 is not particularly limited as long as it is a material that improves the efficiency of extracting electrons from the active layer to the cathode, and examples thereof include inorganic compounds and organic compounds.

  Examples of the material of the inorganic compound include salts of alkali metals such as Li, Na, K or Cs; n-type semiconductor oxides such as titanium oxide (TiOx) and zinc oxide (ZnO). Among them, the alkali metal salt is preferably a fluoride salt such as LiF, NaF, KF or CsF, and the n-type semiconductor oxide is preferably zinc oxide (ZnO). The operation mechanism of such a material is unknown, but it is conceivable to reduce the work function of the cathode when combined with a cathode made of Al or the like and increase the voltage applied to the inside of the solar cell element.

  Examples of organic compound materials include, for example, phosphine compounds having a double bond between a phosphorus atom and a group 16 element such as triarylphosphine oxide compounds; bathocuproin (BCP) or bathophenanthrene (Bphen), A phenanthrene compound which may have a substituent and may be substituted at the 1-position and the 10-position with a heteroatom; a boron compound such as triarylboron; and (8-hydroxyquinolinato) aluminum (Alq3) Organometallic oxide; Compound having 1 or 2 ring structure which may have a substituent such as oxadiazole compound or benzimidazole compound; Naphthalenetetracarboxylic anhydride (NTCDA) or perylenetetracarboxylic acid Of dicarboxylic anhydrides, such as anhydrides (PTCDA) Aromatic compounds having Unachijimigo dicarboxylic acid structure.

  The LUMO energy level of the material of the electron extraction layer is not particularly limited, but is usually −4.0 eV or more, preferably −3.9 eV or more. On the other hand, it is usually −1.9 eV or less, preferably −2.0 eV or less. It is preferable that the LUMO energy level of the material for the electron extraction layer is −1.9 eV or less because charge transfer can be promoted. It is preferable that the LUMO energy level of the material for the electron extraction layer is −4.0 eV or more in terms of preventing reverse electron transfer to the n-type semiconductor material.

The HOMO energy level of the material for the electron extraction layer is not particularly limited, but is usually −9.0 eV or more, preferably −8.0 eV or more. On the other hand, it is usually −5.0 eV or less, preferably −5.5 eV or less. The electron extraction layer material has a HOMO energy level of -5.0.
It is preferable that it is below eV from the point which can prevent a hole from moving.

  As a method for calculating the LUMO energy level and the HOMO energy level of the material of the electron extraction layer, a cyclic voltammogram measurement method may be mentioned. For example, it can implement with reference to the method as described in well-known literature (International Publication 2011/016430).

  When the material of the electron extraction layer is an organic compound, the glass transition temperature (hereinafter sometimes referred to as Tg) of this compound as measured by the DSC method is not particularly limited, but is not observed, or It is preferable that it is 55 degreeC or more. That the glass transition temperature is not observed by the DSC method means that there is no glass transition temperature. Specifically, the determination is made based on the presence or absence of a glass transition temperature of 400 ° C. or lower. A material in which the glass transition temperature by the DSC method is not observed is preferable in that it has high thermal stability.

  Among the compounds having a glass transition temperature of 55 ° C. or higher as measured by the DSC method, the glass transition temperature is preferably 65 ° C. or higher, more preferably 80 ° C. or higher, more preferably 110 ° C. or higher, particularly preferably. Compounds that are 120 ° C. or higher are desirable. On the other hand, the upper limit of the glass transition temperature is not particularly limited, but is usually 400 ° C. or lower, preferably 350 ° C. or lower, more preferably 300 ° C. or lower. Moreover, it is preferable that the material of an electron taking-out layer is a thing by which the glass transition temperature by DSC method is not observed below 30 degreeC or more and less than 55 degree | times.

  The glass transition temperature in the present specification is defined as a point at which specific heat changes in an amorphous solid, which is a temperature at which local molecular motion is started by thermal energy. When the temperature rises further than Tg, the solid structure changes and crystallization occurs (the temperature at this time is defined as the crystallization temperature (Tc)). When the temperature rises further, it generally melts at the melting point (Tm) and changes to a liquid state. However, these phase transitions may not be observed due to molecular decomposition or sublimation at high temperatures.

  The DSC method is a thermophysical property measurement method (differential scanning calorimetry method) defined in JIS K-0129 “General Rules for Thermal Analysis”. In order to determine the glass transition temperature more clearly, it is desirable to measure after rapidly cooling a sample once heated to a temperature higher than the glass transition temperature. For example, the measurement can be carried out by a method described in a known document (International Publication No. 2011/016430).

  When the glass transition temperature of the compound used for the electron extraction layer is 55 ° C. or higher, the structure of this compound is difficult to change against external stress such as applied electric field, flowing current, stress due to bending or temperature change. It is preferable in terms of durability. Furthermore, since there is a tendency that the crystallization of the thin film of the compound does not proceed easily, the stability of the electron extraction layer is improved by making it difficult for the compound to change between the amorphous state and the crystalline state in the operating temperature range. Therefore, it is preferable in terms of durability. This effect becomes more prominent as the glass transition temperature of the material is higher.

  The thickness of the electron extraction layer is not particularly limited, but is usually 0.01 nm or more, preferably 0.1 nm or more, more preferably 0.5 nm or more. On the other hand, it is usually 40 nm or less, preferably 20 nm or less. When the film thickness of the electron extraction layer is 0.01 nm or more, it functions as a buffer material. When the film thickness of the electron extraction layer is 40 nm or less, electrons are easily extracted and the photoelectric conversion efficiency is improved. Can improve.

When an alkali metal salt is used as a material for the electron extraction layer 102, the electron extraction layer 102 can be formed using a vacuum film formation method such as vacuum evaporation or sputtering. In particular, it is desirable to form the electron extraction layer 102 by vacuum deposition using resistance heating. By using vacuum deposition, damage to other layers such as the active layer 103 can be reduced. As for the metal oxide of the n-type semiconductor, for example, when zinc oxide ZnO is used as the material of the electron extraction layer 102, a vacuum film formation method such as a sputtering method can be used. It is desirable to form the layer 102. For example, Sol-Gel Science, C.I. J. et al. Brinker, G.M. W. According to the sol-gel method described by Scherer, Academic Press (1990), the electron extraction layer 102 made of zinc oxide can be formed. The film thickness is usually 0.1 nm or more, preferably 2 nm or more, more preferably 5 nm or more, and usually 1 μm or less, preferably 100 nm or less, more preferably 50 nm or less. If the electron extraction layer 102 is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer 102 acts as a series resistance component and tends to impair the characteristics of the element. When the material of the electron extraction layer 102 is an organic compound, in general, when a material having sublimation properties is used, a vacuum film formation method such as a vacuum evaporation method can be used. In addition, when a material soluble in a solvent is used, a wet coating method such as spin coating or ink jet can be used.

  When the electron extraction layer is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.

(Heating process)
When the formation process of the electron extraction layer 102 is performed by coating, the above heating process is performed thereafter. The heating process may be performed subsequent to the formation process of the electron extraction layer 102, or may be performed after the formation process of the active layer 103, the formation process of the hole extraction layer 104, or the formation process of the anode 105.

[3-3-2. Hole extraction layer (104)]
The material of the hole extraction layer 104 is not particularly limited as long as it is a material capable of improving the efficiency of extracting holes from the active layer 103 to the anode 105. Specifically, polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, or the like, a conductive polymer doped with sulfonic acid and / or iodine, a polythiophene derivative having a sulfonyl group as a substituent, or a conductive organic such as arylamine Examples thereof include compounds, copper oxide, nickel oxide, manganese oxide, molybdenum oxide, vanadium oxide, metal oxide such as tungsten oxide, Nafion, and a p-type semiconductor described later. Among them, a conductive polymer doped with sulfonic acid is preferable, and (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) (PEDOT: PSS) in which a polythiophene derivative is doped with polystyrene sulfonic acid is more preferable. It is. A thin film of metal such as gold, indium, silver or palladium can also be used. A thin film of metal or the like may be formed alone or in combination with the above organic material.

  The thickness of the hole extraction layer 104 is not particularly limited, but is usually 0.2 nm or more. On the other hand, it is usually 400 nm or less, preferably 200 nm or less. When the film thickness of the hole extraction layer 104 is 0.2 nm or more, it functions as a buffer material, and when the film thickness of the hole extraction layer 104 is 400 nm or less, holes are easily extracted. The photoelectric conversion efficiency can be improved.

As a method for forming the hole extraction layer 104, for example, when a material having sublimation property is used, the hole extraction layer 104 can be formed by a vacuum evaporation method or the like. When the hole extraction layer 104 is formed by application using a material soluble in a solvent, the hole extraction layer 104 can be formed by a wet application method such as a spin coating method or an inkjet method. When a semiconductor material is used for the hole extraction layer 104, the precursor may be converted into a semiconductor compound after the layer is formed using the precursor, similarly to the low-molecular organic semiconductor compound of the organic active layer described later.

Especially, when using PEDOT: PSS as a material of the hole taking-out layer 104, it is preferable to form the hole taking-out layer 104 by the method of apply | coating a dispersion liquid. PEDOT: The dispersion of PSS, and CLEVIOS ^TM series of Heraeus, Inc., include Agfa Corp. of ORGACON ^TM series and the like.

  When the hole extraction layer 104 is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.

(Heating process)
When the formation process of the hole extraction layer 104 is performed by coating, the above heating process is performed thereafter. The heating process may be performed subsequent to the formation process of the hole extraction layer 104 or may be performed after the formation process of the anode 105. A heating step after the step of forming the hole extraction layer 104 is preferable because the structure formation of the active layer can be promoted.

[3-4. Active layer (103)]
The manufacturing process of the organic thin film solar cell includes a process of forming the active layer 103.
The active layer 103 refers to a layer in which photoelectric conversion is performed, and usually includes a p-type semiconductor compound and an n-type semiconductor compound. The p-type semiconductor compound is a compound that works as a p-type semiconductor material, and the n-type semiconductor compound is a compound that works as an n-type semiconductor material. When the photoelectric conversion element 107 receives light, the light is absorbed by the active layer 103, electricity is generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound, and the generated electricity is extracted from the electrodes 101 and 105.

  As the material of the active layer 103, either an inorganic compound or an organic compound may be used, but a layer that can be formed by a simple coating process is preferable. More preferably, the active layer 103 is an organic active layer made of an organic compound. In the following description, it is assumed that the active layer 103 is an organic active layer.

  As the layer structure of the active layer 103, a thin film stack type in which a p-type semiconductor compound layer and an n-type semiconductor compound layer are stacked, a bulk heterojunction type having a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed, p And a type semiconductor compound layer, a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed (i layer), and an n-type semiconductor compound layer are stacked. Among these, a bulk heterojunction type having a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed is preferable.

The thickness of the active layer 103 is not particularly limited, but is usually 10 nm or more, preferably 50 nm or more, and is usually 1000 nm or less, preferably 500 nm or less, more preferably 200 nm or less. It is preferable that the thickness of the active layer 103 is 10 nm or more because the uniformity of the film is maintained and a short circuit is less likely to occur. In addition, it is preferable that the thickness of the active layer 103 is 1000 nm or less in that the internal resistance is small and that the diffusion of charges is good without the electrodes 101 and 105 being separated too much.

  The formation process of the active layer 103 is not particularly limited, but is preferably performed by coating. As the coating method, any method can be used, for example, spin coating method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire barber coating method, Examples include the pipe doctor method, the impregnation / coating method, and the curtain coating method.

  For example, the p-type semiconductor compound layer and the n-type semiconductor compound layer can be produced by applying a coating liquid containing a p-type semiconductor compound or an n-type semiconductor compound. Moreover, the layer in which the p-type semiconductor compound and the n-type semiconductor compound are mixed can be prepared by applying a coating solution containing the p-type semiconductor compound and the n-type semiconductor compound. As will be described later, the semiconductor compound precursor may be converted into a semiconductor compound after the coating liquid containing the semiconductor compound precursor is applied.

(Heating process)
When performing the formation process of the active layer 103 by application | coating, said heating process is performed after that. In particular, in the case of a bulk heterojunction type active layer, formation of nanostructures in the layer is promoted by the heating step, whereby charge separation efficiency and charge transport efficiency are promoted, which leads to improvement in battery performance. The heating process may be performed subsequent to the formation process of the active layer 103, or may be performed after the formation process of the hole extraction layer 104 or the formation process of the anode 105.

[3-4-1. p-type semiconductor compound]
The p-type semiconductor compound included in the active layer 103 is not particularly limited, and examples thereof include a low molecular organic semiconductor compound and a high molecular organic semiconductor compound.

[3-4-1-1. Low molecular organic semiconductor compound]
The molecular weight of the low-molecular organic semiconductor compound is not particularly limited both at the upper limit and the lower limit, but is usually 5000 or less, preferably 2000 or less, and is usually 100 or more, preferably 200 or more.

Further, the low molecular organic semiconductor compound preferably has crystallinity. The p-type semiconductor compound having crystallinity has a strong intermolecular interaction, and holes generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound in the active layer 103 can be efficiently transported to the anode 105. In the present specification, crystallinity is a property of a compound that takes a three-dimensional periodic arrangement with uniform orientation due to intermolecular interaction or the like. Examples of the crystallinity measuring method include an X-ray diffraction method (XRD) and a field effect mobility measuring method. In particular, in the field effect mobility measurement, the hole mobility is preferably 1.0 × 10 ⁻⁵ cm ² / Vs or more, and more preferably 1.0 × 10 ⁻⁴ cm ² / Vs or more. On the other hand, the hole mobility is usually preferably 1.0 × 10 ⁴ cm ² / Vs or less, more preferably 1.0 × 10 ³ cm ² / Vs or less, and 1.0 × 10 ² cm. More preferably, it is ² / Vs or less.

  The low-molecular organic semiconductor compound is not particularly limited as long as it can function as a p-type semiconductor material. Specifically, condensed aromatic hydrocarbons such as naphthacene, pentacene, or pyrene; α-sexithiophene, etc. Oligothiophenes containing 4 or more thiophene rings; including at least one of thiophene ring, benzene ring, fluorene ring, naphthalene ring, anthracene ring, thiazole ring, thiadiazole ring and benzothiazole ring, and a total of 4 or more linked A phthalocyanine compound and a metal complex thereof, or a porphyrin compound such as tetrabenzoporphyrin and a macrocycle such as a metal complex thereof. Preferably, they are a phthalocyanine compound and its metal complex, or a porphyrin compound and its metal complex.

Examples of the porphyrin compound and its metal complex (Z ¹ in the figure is CH), and the phthalocyanine compound and its metal complex (Z ¹ in the figure is N) include compounds having the following structures.

Here, M represents a metal or two hydrogen atoms, and the metal includes a divalent metal such as Cu, Zn, Pb, Mg, Pd, Ag, Co, or Ni, and an axial ligand 3 Metals having a valence higher than that, for example, TiO, VO, SnCl ₂ , AlCl, InCl, Si, and the like are also included.

R ^{11 to} R ¹⁴ are each independently a hydrogen atom or an alkyl group having 1 to 24 carbon atoms. The alkyl group having 1 to 24 carbon atoms is a saturated or unsaturated chain hydrocarbon group having 1 to 24 carbon atoms or a saturated or unsaturated cyclic hydrocarbon group having 3 to 24 carbon atoms. Among these, a saturated or unsaturated chain hydrocarbon group having 1 to 12 carbon atoms or a saturated or unsaturated cyclic hydrocarbon group having 3 to 12 carbon atoms is preferable.

  Among the phthalocyanine compounds and metal complexes thereof, 29H, 31H-phthalocyanine, copper phthalocyanine complex, zinc phthalocyanine complex, titanium phthalocyanine oxide complex, magnesium phthalocyanine complex, lead phthalocyanine complex or copper 4,4 ′, 4 ″, 4 '' '-Tetraaza-29H, 31H-phthalocyanine complex, more preferably 29H, 31H-phthalocyanine or copper phthalocyanine complex. One of the above compounds may be used, or a mixture of a plurality of compounds may be used.

  Among the porphyrin compounds and metal complexes thereof, 5,10,15,20-tetraphenyl-21H, 23H-porphine, 5,10,15,20-tetraphenyl-21H, 23H-porphine cobalt (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine copper (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine zinc (II), 5,10,15,20- Tetraphenyl-21H, 23H-porphine nickel (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine vanadium (IV) oxide, 5,10,15,20-tetra (4-pyridyl)- 21H, 23H-porphine, 29H, 31H-tetrabenzo [b, g, l, q] porphine, 2 H, 31H-tetrabenzo [b, g, l, q] porphine cobalt (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine copper (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine zinc (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine nickel (II) or 29H, 31H-tetrabenzo [b, g, l, q] porphine vanadium (IV) oxide And preferably 5,10,15,20-tetraphenyl-21H, 23H-porphine or 29H, 31H-tetrabenzo [b, g, l, q] porphine. One of the above compounds may be used, or a mixture of a plurality of compounds may be used.

  Examples of the method for forming a low molecular organic semiconductor compound include a vapor deposition method and a coating method. The latter is preferred because of the process advantage that coating can be formed. When the coating method is used, there is a method of converting a low molecular organic semiconductor compound precursor into a low molecular organic semiconductor compound after coating. A method using a semiconductor compound precursor is more preferable in that coating film formation is easier.

(Low molecular organic semiconductor compound precursor)
A low molecular organic semiconductor compound precursor is a compound that changes its chemical structure and is converted into a low molecular organic semiconductor compound by applying an external stimulus such as heating or light irradiation. The low molecular organic semiconductor compound precursor is preferably excellent in film formability. In particular, in order to be able to apply the coating method, it is preferable that the precursor itself can be applied in a liquid state, or the precursor is highly soluble in some solvent and can be applied as a solution. For this reason, the solubility with respect to the solvent of a low molecular organic-semiconductor compound precursor is usually 0.1 weight% or more, Preferably it is 0.5 weight% or more, More preferably, it is 1 weight% or more. On the other hand, the upper limit is not particularly limited, but is usually 50% by weight or less, preferably 40% by weight or less.

The type of the solvent is not particularly limited as long as it can uniformly dissolve or disperse the semiconductor precursor compound. For example, aliphatic hydrocarbons such as hexane, heptane, octane, isooctane, nonane or decane; toluene, xylene , Aromatic hydrocarbons such as cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; lower alcohols such as methanol, ethanol or propanol; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; ethyl acetate, butyl acetate or methyl lactate Esters such as: Chloroform, methylene chloride, dichloroethane, trichloroethane, trichloroethylene, and other halogen hydrocarbons; Ethyl ether, tetrahydrofuran, dioxane, and other ethers; Dimethyl Formamide or amides such as dimethylacetamide and the like. Among them, preferably, aromatic hydrocarbons such as toluene, xylene, cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; chloroform, methylene chloride, dichloroethane, trichloroethane or trichloroethylene Halogen hydrocarbons; ethers such as ethyl ether, tetrahydrofuran or dioxane. More preferably, non-halogen aromatic hydrocarbons such as toluene, xylene or cyclohexylbenzene; non-halogen ketones such as cyclopentanone or cyclohexanone; non-halogen aliphatic ethers such as tetrahydrofuran or 1,4-dioxane is there. Particularly preferred are non-halogen aromatic hydrocarbons such as toluene, xylene or cyclohexylbenzene. In addition, 1 type of solvent may be used independently and 2 or more types of solvents may be used together by arbitrary combinations and a ratio.

  Furthermore, it is preferable that the low molecular organic semiconductor compound precursor can be easily converted into a semiconductor compound. In the step of converting a low molecular organic semiconductor compound precursor to a semiconductor compound, which will be described later, what kind of external stimulus is given to the semiconductor precursor is arbitrary, but usually heat treatment or light treatment is performed. Preferably, it is heat treatment. In this case, the low-molecular organic semiconductor compound precursor preferably has a solvophilic group with respect to a predetermined solvent, which can be eliminated by a reverse Diels-Alder reaction as a part of the skeleton.

  Moreover, it is preferable that a low molecular organic-semiconductor compound precursor is converted into a semiconductor compound with a high yield through a conversion process. In this case, the yield of the semiconductor compound obtained by conversion from the low molecular organic semiconductor compound precursor is arbitrary as long as the performance of the photoelectric conversion element is not impaired, but the low molecular organic semiconductor obtained from the low molecular organic semiconductor compound precursor The yield of the compound is usually 90 mol% or more, preferably 95 mol% or more, more preferably 99 mol% or more.

  The low molecular organic semiconductor compound precursor is not particularly limited as long as it has the above characteristics, and specifically, compounds described in JP-A-2007-324587 can be used. Particularly preferred examples include compounds represented by the following formula.

In the above formula, at least one of D ¹ and D ² represents a group that forms a π-conjugated divalent aromatic ring, Z ² —Z ³ is a group that can be removed by heat or light, and Z ² A π-conjugated compound obtained by elimination of —Z ³ represents a low molecular organic semiconductor compound. In addition, D ¹ and D ² which are not a group that forms a π-conjugated divalent aromatic ring represent a substituted or unsubstituted ethenylene group.

In the compound represented by the above formula, Z ² —Z ³ is eliminated by heat or light as shown in the following chemical reaction formula to form a π-conjugated compound having high planarity. This produced π-conjugated compound is a low-molecular organic semiconductor compound. This low molecular organic semiconductor compound is used as a material having p-type semiconductor characteristics.

  The following are mentioned as an example of a low molecular organic-semiconductor compound precursor. In the following, t-Bu represents a t-butyl group, and M is the same as described for porphyrin and phthalocyanine.

  Specific examples of the conversion of the low-molecular organic semiconductor compound precursor into the low-molecular organic semiconductor compound include the following.

  The low molecular organic semiconductor compound precursor may have a structure in which positional isomers exist, and in that case, it may be a mixture of a plurality of positional isomers. A mixture of a plurality of positional isomers is preferable because it has a higher solubility in a solvent than a low-molecular organic semiconductor compound precursor composed of a single positional isomer component, and is easy to form a coating film. The reason why the solubility of the mixture of multiple positional isomers is high is that the detailed mechanism is not clear, but the crystallinity of the compound itself is potentially retained, but the mixture of multiple isomers is mixed in the solution. It is assumed that three-dimensional regular intermolecular interaction becomes difficult. The solubility of the mixture of a plurality of regioisomers in a non-halogen solvent is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more. Although there is no restriction | limiting in an upper limit, Usually, it is 50 weight% or less, More preferably, it is 40 weight% or less.

[3-4-1-2. Polymeric organic semiconductor compound]
The polymer organic semiconductor compound is not particularly limited, and is a conjugated polymer semiconductor such as polythiophene, polyfluorene, polyphenylene vinylene, polythienylene vinylene, polyacetylene or polyaniline; a polymer such as oligothiophene substituted with an alkyl group or other substituents Semiconductor; and the like. Moreover, the semiconductor polymer which copolymerized 2 or more types of monomer units is also mentioned. The conjugated polymers, ^{e.g., Handbook of Conducting Polymers, 3 rd} Ed. (2 volumes), 2007, Materials Science and Engineering, 2001, 32, 1-40, Pure Appl. Chem. Use polymers that can be synthesized by a combination of polymers described in known literature such as 2002, 74, 2031-3044, Handbook of THIOPHENE-BASED MATERIALS (2 volumes), 2009, and derivatives thereof, and combinations of the described monomers. Can do. The polymer organic semiconductor compound used as the p-type semiconductor compound may be a single compound or a mixture of a plurality of compounds.

  The monomer skeleton and monomer substituent of the polymer organic semiconductor compound can be selected to control the solubility, crystallinity, film-forming property, HOMO energy level, LUMO energy level, and the like. In addition, it is preferable that the polymer organic semiconductor compound is soluble in an organic solvent in that the active layer 103 can be formed by a coating method when a photoelectric conversion element is manufactured. Specific examples of the polymer organic semiconductor compound include the following, but are not limited thereto.

  Among the p-type semiconductor compounds, the low-molecular organic semiconductor compound is preferably a condensed aromatic hydrocarbon such as naphthacene, pentacene, or pyrene, a phthalocyanine compound and a metal complex thereof, or a porphyrin compound such as tetrabenzoporphyrin (BP) and The metal complex and the polymer organic semiconductor compound is a conjugated polymer semiconductor such as polythiophene. The p-type semiconductor compound used in the active layer 103 may be a single compound or a mixture of multiple compounds.

  The low-molecular organic semiconductor compound and / or the high-molecular organic semiconductor compound may have some self-organized structure in the film-formed state, or may be in an amorphous state.

  The HOMO (highest occupied molecular orbital) energy level of the p-type semiconductor compound is not particularly limited, and can be selected according to the type of the n-type semiconductor compound described later. In particular, when a fullerene compound is used as an n-type semiconductor compound, the HOMO energy level of the p-type semiconductor compound is usually −5.7 eV or more, more preferably −5.5 eV or more, on the other hand, usually −4.6 eV or less. Preferably it is -4.8 eV or less. When the HOMO energy level of the p-type semiconductor compound is −5.7 eV or more, the characteristics as a p-type semiconductor are improved, and when the HOMO energy level of the p-type semiconductor compound is −4.6 eV or less, Stability is improved and the open circuit voltage (Voc) is also improved.

The LUMO (lowest unoccupied molecular orbital) energy level of the p-type semiconductor compound is not particularly limited, but can be selected according to the type of the n-type semiconductor compound described later. In particular, when a fullerene compound is used as an n-type semiconductor compound, the LUMO energy level of the p-type semiconductor compound is usually −3.7 eV or more, preferably −3.6 eV or more. On the other hand, it is usually −2.5 eV or less, preferably −2.7 eV or less. When the LUMO energy level of the p-type semiconductor is −2.5 eV or less, the band gap is adjusted, light energy having a long wavelength can be effectively absorbed, and the short-circuit current density is improved. When the LUMO energy level of the p-type semiconductor compound is −3.7 eV or more, electron transfer to the n-type semiconductor compound is likely to occur and the short-circuit current density is improved.

[3-4-2. n-type semiconductor compound]
The n-type semiconductor compound is not particularly limited. Specifically, it is a fullerene compound, a quinolinol derivative metal complex represented by 8-hydroxyquinoline aluminum; a condensed ring such as naphthalenetetracarboxylic acid diimide or perylenetetracarboxylic acid diimide. Tetracarboxylic acid diimides; perylene diimide derivatives, terpyridine metal complexes, tropolone metal complexes, flavonol metal complexes, perinone derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazole derivatives, benzthiazole derivatives, benzothiadiazole derivatives, oxadiazole derivatives, thiadiazoles Derivatives, triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, benzoquinoline derivatives Bipyridine derivatives, borane derivatives, anthracene, pyrene, total fluoride condensed polycyclic aromatic hydrocarbons such as naphthacene or pentacene; single-walled carbon nanotubes, and the like.

  Among them, fullerene compounds, borane derivatives, thiazole derivatives, benzothiazole derivatives, benzothiadiazole derivatives, N-alkyl-substituted naphthalenetetracarboxylic acid diimides and N-alkyl-substituted perylene diimide derivatives are preferable, and fullerene compounds, N- Alkyl substituted perylene diimide derivatives and N-alkyl substituted naphthalene tetracarboxylic acid diimides are more preferred. One of the above compounds may be used, or a mixture of a plurality of compounds may be used. Examples of the n-type semiconductor compound include an n-type polymer semiconductor compound.

  The LUMO energy level of the n-type semiconductor compound is not particularly limited. For example, the value with respect to the vacuum level calculated by the cyclic voltammogram measurement method is usually −3.85 eV or more, preferably −3.80 eV or more. . In order to efficiently transfer electrons from a p-type semiconductor compound to an n-type semiconductor compound, the relative relationship of LUMO energy levels between the p-type semiconductor compound and the n-type semiconductor compound is important. Specifically, the LUMO energy level of the p-type semiconductor compound is above the LUMO energy level of the n-type semiconductor compound by a predetermined value, in other words, the electron affinity of the n-type semiconductor compound is p-type semiconductor compound. It is preferable that a predetermined energy is larger than the electron affinity. Since the open circuit voltage (Voc) depends on the difference between the HOMO energy level of the p-type semiconductor compound and the LUMO energy level of the n-type semiconductor compound, increasing the LUMO of the n-type semiconductor compound tends to increase Voc. On the other hand, the LUMO value is usually −1.0 eV or less, preferably −2.0 eV or less, more preferably −3.0 eV or less, and still more preferably −3.3 eV or less. By lowering the LUMO energy level of the n-type semiconductor compound, electrons tend to move and the short circuit current (Jsc) tends to increase.

  As a method for calculating the LUMO energy level of an n-type semiconductor compound, there are a theoretically calculated method and a method of actually measuring. Theoretically calculated methods include semi-empirical molecular orbital methods and non-empirical molecular orbital methods. Examples of the actual measurement method include an ultraviolet-visible absorption spectrum measurement method and a cyclic voltammogram measurement method. Among them, the cyclic voltammogram measurement method is preferable.

The HOMO energy level of the n-type semiconductor compound is not particularly limited, but is usually −5.0 eV or less, preferably −5.5 eV or less. On the other hand, it is usually −7.0 eV or more, preferably −6.6 eV or more. It is preferable that the HOMO energy level of the n-type semiconductor compound is −7.0 eV or more because light absorption of the n-type semiconductor compound can also be used for power generation. The HOMO energy level of the n-type semiconductor compound is preferably −5.0 eV or less from the viewpoint of preventing reverse movement of holes.

The electron mobility of the n-type semiconductor compound is not particularly limited, but is usually 1.0 × 10 ⁻⁶ cm ² / Vs or more, preferably 1.0 × 10 ⁻⁵ cm ² / Vs or more. 0 × 10 ⁻⁵ cm ² / Vs or more is more preferable, and 1.0 × 10 ⁻⁴ cm ² / Vs or more is more preferable. On the other hand, it is usually 1.0 × 10 ³ cm ² / Vs or less, preferably 1.0 × 10 ² cm ² / Vs or less, and more preferably 5.0 × 10 ¹ cm ² / Vs or less. The fact that the electron mobility of the n-type semiconductor compound is 1.0 × 10 ⁻⁶ cm ² / Vs or more can provide effects such as improvement of the electron diffusion rate, improvement of short-circuit current, and improvement of conversion efficiency of the photoelectric conversion element. Is preferable. As a method for measuring electron mobility, there is a field effect transistor (FET) method, which can be carried out by a method described in a known document (Japanese Patent Laid-Open No. 2010-045186).

  The solubility of the n-type semiconductor compound in toluene at 25 ° C. is usually 0.5% by weight or more, preferably 0.6% by weight or more, and more preferably 0.7% by weight or more. On the other hand, it is usually preferably 90% by weight or less, more preferably 80% by weight or less, and further preferably 70% by weight or less. When the solubility of the n-type semiconductor compound in toluene at 25 ° C. is 0.5% by weight or more, the dispersion stability of the n-type semiconductor compound in the solution is improved, and aggregation, sedimentation, separation, and the like are less likely to occur. Therefore, it is preferable.

  Hereinafter, examples of preferable n-type semiconductor compounds will be described.

[3-4-2-1. Fullerene compound]
As a fullerene compound, what has the partial structure represented by general formula (n1), (n2), (n3), and (n4) is mentioned as a preferable example.

In the above formula, FLN represents fullerene, which is a carbon cluster having a closed shell structure. The carbon number of fullerene is not particularly limited as long as it is an even number of usually 60 or more and 130 or less. As the fullerene, for example, C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C _9
6 and higher-order carbon clusters having more carbon than these. Among these, _C60 or _C70 is preferable. As fullerenes, carbon-carbon bonds on some fullerene rings may be broken. Moreover, some of the carbon atoms constituting the fullerene may be replaced with other atoms. Further, the fullerene may include a metal atom, a non-metal atom, or an atomic group composed of these in a fullerene cage.

a, b, c and d are integers, and the sum of a, b, c and d is usually 1 or more, and usually 5 or less, preferably 3 or less. The partial structures in (n1), (n2), (n3) and (n4) are bonded to the same 5-membered ring or 6-membered ring in the fullerene skeleton. In the general formula (n1), —R ²¹ and — (CH ₂ ) _L are bonded to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton. . In the general formula (n2), -C (R ²⁵ ) (R ²⁶ ) -N (R ²⁷ ) -C with respect to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton. (R ²⁸ ) (R ²⁹ ) — are added to form a 5-membered ring. In the general formula (n3), —C (R ³⁰ ) (R ³¹ ) —C—C—C (R) with respect to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton. ³² ) (R ³³ ) — are added to form a 6-membered ring. In the general formula (n4), —C (R ³⁴ ) (R ³⁵ ) — is added to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton to form a 3-membered ring. Forming. L is an integer of 1 to 8. L is preferably an integer of 1 to 4, more preferably an integer of 1 to 2.

R ²¹ in the general formula (n1) is an alkyl group having 1 to 14 carbon atoms which may have a substituent, an alkoxy group having 1 to 14 carbon atoms which may have a substituent, or a substituent. An aromatic group which may have a group.

  The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group or an isobutyl group, and even more preferably a methyl group or an ethyl group. . The alkoxy group is preferably an alkoxy group having 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 6 carbon atoms, and particularly preferably a methoxy group or an ethoxy group. The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, more preferably a phenyl group, a thienyl group, a furyl group, or a pyridyl group. More preferred are groups or thienyl groups.

  Although it does not specifically limit as a substituent which said alkyl group, an alkoxy group, and an aromatic group may have, A halogen atom or a silyl group is preferable. As the halogen atom, a fluorine atom is preferable. The silyl group is preferably a diarylalkylsilyl group, a dialkylarylsilyl group, a triarylsilyl group or a trialkylsilyl group, more preferably a dialkylarylsilyl group, and even more preferably a dimethylarylsilyl group.

R ^{22 to} R ²⁴ in the general formula (n1) may each independently have a hydrogen atom, an alkyl group having 1 to 14 carbon atoms which may have a substituent, or a substituent. It is an aromatic group.

  As the alkyl group, an alkyl group having 1 to 10 carbon atoms is preferable, and a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, or an n-hexyl group is preferable. . The substituent that the alkyl group may have is preferably a halogen atom. As the halogen atom, a fluorine atom is preferable. The alkyl group substituted with a fluorine atom is preferably a perfluorooctyl group, a perfluorohexyl group or a perfluorobutyl group.

  The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, more preferably a phenyl group, a thienyl group, a furyl group, or a pyridyl group. More preferred are groups or thienyl groups. The substituent that the aromatic group may have is not particularly limited, but is a fluorine atom, an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, or a carbon atom having 1 to 14 carbon atoms. An alkoxy group or an aromatic group having 3 to 10 carbon atoms is preferred, a fluorine atom or an alkoxy group having 1 to 14 carbon atoms is more preferred, and a methoxy group, n-butoxy group or 2-ethylhexyloxy group is still more preferred. When the aromatic group has a substituent, the number is not limited, but is preferably 1 or more and 3 or less, and more preferably 1. When the aromatic group has a plurality of substituents, the types of the substituents may be different, but are preferably the same.

R ^{25 to} R ²⁹ in the general formula (n2) may each independently have a hydrogen atom, an alkyl group having 1 to 14 carbon atoms which may have a substituent, or a substituent. It is an aromatic group.

  The alkyl group is preferably a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-hexyl group or octyl group, and more preferably a methyl group. The substituent that the alkyl group may have is not particularly limited, but a halogen atom is preferable. As the halogen atom, a fluorine atom is preferable. The alkyl group substituted with a fluorine atom is preferably a perfluorooctyl group, a perfluorohexyl group or a perfluorobutyl group.

  As the aromatic group, an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms is preferable, a phenyl group or a pyridyl group is more preferable, and a phenyl group is further preferable. Although it does not specifically limit as a substituent which an aromatic group may have, Preferably they are a fluorine atom, a C1-C14 alkyl group, or a C1-C14 alkoxy group. The alkyl group may be substituted with a fluorine atom. More preferably, it is an alkoxy group having 1 to 14 carbon atoms, and more preferably a methoxy group. When it has a substituent, the number is not limited, but it is preferably 1 or more and 3 or less, more preferably 1. The types of substituents may be different, but are preferably the same.

Ar ¹ in the general formula (n3) is an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, preferably A phenyl group, a naphthyl group, a biphenyl group, a thienyl group, a furyl group, a pyridyl group, a pyrimidyl group, a quinolyl group or a quinoxalyl group, more preferably a phenyl group, a thienyl group or a furyl group.

  Although there is no limitation as a substituent which may have, an amino group which may be substituted with a fluorine atom, a chlorine atom, a hydroxyl group, a cyano group, a silyl group, a boryl group or an alkyl group, having 1 to 14 carbon atoms An alkyl group, an alkoxy group having 1 to 14 carbon atoms, an alkylcarbonyl group having 2 to 14 carbon atoms, an alkylthio group having 1 to 14 carbon atoms, an alkenyl group having 2 to 14 carbon atoms, and 2 to 14 carbon atoms An alkynyl group, an ester group having 2 to 14 carbon atoms, an arylcarbonyl group having 3 to 20 carbon atoms, an arylthio group having 2 to 20 carbon atoms, an aryloxy group having 2 to 20 carbon atoms, and 6 or more carbon atoms An aromatic hydrocarbon group having 20 or less or a heterocyclic group having 2 to 20 carbon atoms is preferable, a fluorine atom, an alkyl group having 1 to 14 carbon atoms, 1 or less carbon atoms 1 An alkoxy group, having 2 to 14 ester groups carbons, an alkyl group or having 3 to 20 arylcarbonyl group carbons of 2 to 14 carbon atoms and more preferable. The alkyl group having 1 to 14 carbon atoms may be substituted with 1 or 2 or more fluorine atoms.

  The alkyl group having 1 to 14 carbon atoms is preferably a methyl group, an ethyl group or a propyl group. The alkoxy group having 1 to 14 carbon atoms is preferably a methoxy group, an ethoxy group, or a propoxy group. The alkylcarbonyl group having 1 to 14 carbon atoms is preferably an acetyl group. The ester group having 2 to 14 carbon atoms is preferably a methyl ester group or an n-butyl ester group. The arylcarbonyl group having 3 to 20 carbon atoms is preferably a benzoyl group.

  When it has a substituent, the number is not limited, but it is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less. When there are a plurality of substituents, the types may be different, but are preferably the same.

R ^{30 to} R ³³ in the general formula (n3) each independently have a hydrogen atom, an alkyl group which may have a substituent, an amino group which may have a substituent, or a substituent. It is an optionally substituted alkoxy group or an optionally substituted alkylthio group. R ³⁰ or R ³¹ may be bonded to any one of R ³² and R ³³ to form a ring. As a structure in the case of forming a ring, the structure shown to the general formula (n5) which is a bicyclo structure which the aromatic group condensed is mentioned, for example.

F In the general formula (n5) has the same meaning as c, Z ⁴ is an oxygen atom, a sulfur atom, an amino group, an alkylene group or an arylene group. The alkylene group preferably has 1 to 2 carbon atoms. The arylene group preferably has 5 to 12 carbon atoms, and examples thereof include a phenylene group. The amino group may be substituted with an alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group. The alkylene group is an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or 2 to 20 carbon atoms. The aromatic heterocyclic group may be substituted. The arylene group is an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or 2 to 20 carbon atoms. The aromatic heterocyclic group may be substituted.

  The structure represented by the formula (n5) is particularly preferably a structure represented by the following formula (n6) or formula (n7).

R ^{34 to} R ³⁵ in the general formula (n4) each independently have a hydrogen atom, an alkoxycarbonyl group, an alkyl group having 1 to 14 carbon atoms which may have a substituent, or a substituent. An aromatic group that may be present.

  The alkoxy group constituting the alkoxycarbonyl group is preferably an alkoxy group having 1 to 12 carbon atoms or a fluorinated alkoxy group having 1 to 12 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and a methoxy group. Ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, n-hexoxy group, octoxy group, 2-propylpentoxy group, 2-ethylhexoxy group, cyclohexylmethoxy group or benzyloxy group A methoxy group, an ethoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group or an n-hexoxy group is particularly preferable.

  As the alkyl group, a linear alkyl group having 1 to 8 carbon atoms is preferable, and an n-propyl group is more preferable. The substituent that the alkyl group may have is not particularly limited, but is preferably an alkoxycarbonyl group. The alkoxy group constituting the alkoxycarbonyl group is preferably an alkoxy group having 1 to 14 carbon atoms or a fluorinated alkoxy group, more preferably a hydrocarbon group having 1 to 14 carbon atoms, a methoxy group, an ethoxy group, n- Propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, n-hexoxy group, octoxy group, 2-propylpentoxy group, 2-ethylhexoxy group, cyclohexylmethoxy group or benzyloxy group are more preferable, methoxy group or n A butoxy group is particularly preferred.

  As the aromatic group, an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms is preferable, and a phenyl group, a biphenyl group, a thienyl group, a furyl group, or a pyridyl group is preferable. More preferred are a phenyl group and a thienyl group. The substituent that the aromatic group may have is preferably an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, or an alkoxy group having 1 to 14 carbon atoms. An alkoxy group having a number of 1 or more and 14 or less is more preferable, and a methoxy group or 2-ethylhexyloxy group is particularly preferable. When it has a substituent, the number is not limited, but it is preferably 1 or more and 3 or less, more preferably 1. The types of substituents may be different or the same, preferably the same.

As the structure of the general formula (n4), preferably R ³⁴ and R ³⁵ are both alkoxycarbonyl groups, R ³⁴ and R ³⁵ are both aromatic groups, or R ³⁴ is an aromatic group and R ^{And those in which 35} is a 3- (alkoxycarbonyl) propyl group.

  As the fullerene compound, one kind of the above compounds may be used, or a mixture of plural kinds of compounds may be used.

In order to form a fullerene compound by a coating method, it is preferable that the fullerene compound itself can be applied in a liquid state, or that the fullerene compound is highly soluble in some solvent and can be applied as a solution. As a preferable range of solubility, the solubility in toluene at 25 ° C. is usually 0.1% by weight or more, preferably 0.4% by weight or more, more preferably 0.7% by weight or more. It is preferable that the solubility of the fullerene compound is 0.1% by weight or more because the dispersion stability of the fullerene compound in the solution increases and aggregation, sedimentation, separation, and the like are less likely to occur.

  The solvent for dissolving the fullerene compound is not particularly limited as long as it is a nonpolar organic solvent, but a non-halogen solvent is preferable. Although it is possible to use a halogen-based solvent such as dichlorobenzene, an alternative is demanded from the viewpoint of environmental load. Examples of non-halogen solvents include non-halogen aromatic hydrocarbons. Of these, toluene, xylene, cyclohexylbenzene, and the like are preferable.

(Method for producing fullerene compound)
Although there is no restriction | limiting in particular as a manufacturing method of a fullerene compound, For example, the synthesis | combination of the fullerene compound which has a partial structure (n1) is international publication 2008/059771 or J.N. Am. Chem. Soc. , 2008, 130 (46), 15429-15436.

  Synthesis of fullerene compounds having a partial structure (n2) is described in J. Org. Am. Chem. Soc. 1993, 115, 9798-9799, Chem. Mater. 2007, 19, 5363-5372 and Chem. Mater. It can be carried out according to the description of known documents such as 2007, 19, 5194-5199.

  Synthesis of a fullerene compound having a partial structure (n3) is described in Angew. Chem. Int. Ed. Engl. 1993, 32, 78-80, Tetrahedron Lett. It can be carried out according to the description of known documents such as 1997, 38, 285-288, WO 2008/018931 and WO 2009/086212.

  Synthesis of fullerene compounds having a partial structure (n4) is described in J. Org. Chem. Soc. Perkin Trans. 1, 1997 1595, Thin Solid Films 489 (2005) 251-256, Adv. Funct. Mater. 2005, 15, 1979-1987 and J. Org. Org. Chem. It can be carried out according to the description of known documents such as 1995, 60, 532-538.

[3-4-2-2. N-alkyl substituted perylene diimide derivatives]
N-alkyl-substituted perylene diimide derivatives are not particularly limited, and specifically, International Publication No. 2008/063609, International Publication No. 2009/115553, International Publication No. 2009/098250, International Publication No. Examples thereof include compounds described in 2009/000756 and International Publication No. 2009/091670. These compounds are preferable in that they have high electron mobility and can absorb light in the visible range, and thus can contribute to both charge transport and power generation.

[3-4-2-3. Naphthalenetetracarboxylic acid diimide]
The naphthalenetetracarboxylic acid diimide is not particularly limited, and specific examples thereof include compounds described in International Publication No. 2008/063609, International Publication No. 2007/146250 and International Publication No. 2009/000756. It is done. These compounds are preferable because they have high electron mobility, high solubility, and excellent coating properties.

[3-4-2-4. N-type polymer semiconductor compound]
There are no particular restrictions on the n-type polymer semiconductor compound, but condensed ring tetracarboxylic acid diimides such as naphthalenetetracarboxylic acid diimide and perylenetetracarboxylic acid diimide, perylene diimide derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazoles N-type polymer semiconductor comprising at least one of a derivative, a benzothiazole derivative, a benzothiadiazole derivative, an oxadiazole derivative, a thiadiazole derivative, a triazole derivative, a pyrazine derivative, a phenanthroline derivative, a quinoxaline derivative, a bipyridine derivative and a borane derivative Compounds and the like.

  Among them, a polymer having at least one of a borane derivative, a thiazole derivative, a benzothiazole derivative, a benzothiadiazole derivative, an N-alkyl-substituted naphthalenetetracarboxylic acid diimide and an N-alkyl-substituted perylene diimide derivative as a constituent unit is provided. Preferably, an n-type polymer semiconductor compound having at least one of N-alkyl-substituted perylene diimide derivative and N-alkyl-substituted naphthalenetetracarboxylic acid diimide as a constituent unit is more preferable. One of the above compounds may be used as the n-type polymer semiconductor compound, or a mixture of a plurality of compounds may be used.

  Specific examples of the n-type polymer semiconductor compound include compounds described in International Publication No. 2009/098253, International Publication No. 2009/098250, International Publication No. 2010/012710, and International Publication No. 2009/098250. Can be mentioned. Since these compounds can absorb light in the visible range, they can contribute to power generation, are preferred because of their high viscosity and excellent coating properties.

[3-5. Solar cell manufacturing method]
There is no restriction | limiting in particular in the manufacturing system of the manufacturing method of the organic thin film solar cell of this invention, Although a single wafer system, a roll to roll system, etc. are mentioned, A roll to roll system is preferable. At least one of the above-described anode formation step, cathode formation step, active layer formation step, electron extraction layer formation step, hole extraction layer formation step, and heating step is roll-to-roll. It is preferable to carry out the method.

The roll-to-roll method is a method of carrying out each process until the substrate wound in a roll shape is fed out intermittently or while being wound up by a winding roll, Since it is possible to batch-process long substrates of km order, mass production can be easily performed, which is preferable. In the roll-to-roll method, the substrate is usually subjected to a tensile stress of about ² N / mm ² or more. The production method that receives such tensile stress is not limited to the roll-to-roll method, and the residual elongation rate of the base material is likely to increase.

[3-6. Photoelectric conversion characteristics]
The photoelectric conversion characteristics of the photoelectric conversion element 107 can be obtained as follows. The photoelectric conversion element 107 is irradiated with light having an AM1.5G condition at an irradiation intensity of 100 mW / cm ^{2 using a} solar simulator, and current-voltage characteristics are measured. From the obtained current-voltage curve, photoelectric conversion characteristics such as photoelectric conversion efficiency (PCE), short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), series resistance, and shunt resistance can be obtained.

  The photoelectric conversion efficiency of the photoelectric conversion element according to the present invention is not particularly limited, but is usually 1% or more, preferably 1.5% or more, more preferably 2% or more. On the other hand, there is no particular limitation on the upper limit, and the higher the better.

Moreover, as a method for measuring the durability of the photoelectric conversion element, a method for obtaining a maintenance ratio of the photoelectric conversion efficiency before and after exposing the photoelectric conversion element to the atmosphere can be mentioned.
(Maintenance rate) = (Photoelectric conversion efficiency after N hours of atmospheric exposure) / (Photoelectric conversion efficiency immediately before atmospheric exposure)

  In order to put a photoelectric conversion element into practical use, it is important to have high photoelectric conversion efficiency and high durability in addition to simple and inexpensive manufacture. From this viewpoint, the maintenance rate of photoelectric conversion efficiency before and after exposure to the atmosphere for one week is preferably 60% or more, more preferably 80% or more, and the higher the better.

  Hereinafter, although the organic thin-film solar cell which concerns on this invention is demonstrated with reference to drawings, this invention is not necessarily limited only to such an embodiment.

<4. Solar Cell According to the Present Invention>
The photoelectric conversion element 107 according to the present invention is preferably used as a solar cell, particularly a solar cell element of a thin film solar cell.

  FIG. 2 is a cross-sectional view schematically showing the configuration of a thin film solar cell as one embodiment of the present invention. As shown in FIG. 2, the thin film solar cell 14 of this embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell element. 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 are provided in this order. And light is irradiated from the side (downward in the figure) where the weather-resistant protective film 1 is formed, and the solar cell element 6 generates power. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good.

[4-1. Weatherproof protective film (1)]
The weather-resistant protective film 1 is a film that protects the solar cell element 6 from weather changes. By covering the solar cell element 6 with the weather-resistant protective film 1, the solar cell element 6 and the like are protected from weather changes and the power generation capacity is kept high. Since the weather resistant protective film 1 is located on the outermost layer of the thin film solar cell 14, the surface covering material of the thin film solar cell 14 such as weather resistance, heat resistance, transparency, water repellency, stain resistance and / or mechanical strength is provided. It is preferable to have a property suitable for the above and to maintain it for a long period of time in outdoor exposure.

  Moreover, it is preferable that the weather-resistant protective film 1 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, and the upper limit is not limited. Furthermore, since the thin-film solar cell 14 is often heated by receiving light, it is preferable that the weather-resistant protective film 1 also has heat resistance. From this viewpoint, the melting point of the constituent material of the weather-resistant protective film 1 is usually 100 ° C. or higher and 350 ° C. or lower.

  The material which comprises the weather-resistant protective film 1 is arbitrary as long as it can protect the solar cell element 6 from a weather change. Examples of the material include polyethylene resin, polypropylene resin, cyclic polyolefin resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, polyvinyl chloride resin, fluorine resin, polyethylene terephthalate, polyethylene Examples thereof include polyester resins such as naphthalate, phenol resins, polyacrylic resins, polyamide resins such as various nylons, polyimide resins, polyamide-imide resins, polyurethane resins, cellulose resins, silicon resins, and polycarbonate resins.

  In addition, the weather-resistant protective film 1 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the weather-resistant protective film 1 may be formed with the single layer film, the laminated | multilayer film provided with the film of two or more layers may be sufficient as it.

  The thickness of the weather-resistant protective film 1 is not particularly defined, but is usually 10 μm or more and 200 μm or less.

  Moreover, you may perform surface treatment, such as a corona treatment and / or a plasma treatment, for the weather-resistant protective film 1 in order to improve the adhesiveness with another film.

  The weatherproof protective film 1 is preferably provided on the outer side as much as possible in the thin-film solar cell 14. This is because more of the constituent members of the thin-film solar cell 14 can be protected.

[4-2. UV cut film (2)]
The ultraviolet cut film 2 is a film that prevents the transmission of ultraviolet rays. The ultraviolet cut film 2 is provided in the light receiving portion of the thin-film solar cell 14, and the ultraviolet cut film 2 covers the light receiving surface 6a of the solar cell element 6, so that the solar cell element 6 and, if necessary, the gas barrier films 3 and 9 are exposed to ultraviolet rays. The power generation capacity can be maintained at a high level.

  The degree of the ability to suppress the transmission of ultraviolet rays required for the ultraviolet cut film 2 is preferably such that the transmittance of ultraviolet rays (for example, wavelength of 300 nm) is 50% or less, and there is no limit on the lower limit. Moreover, it is preferable that the ultraviolet cut film 2 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, and the upper limit is not limited.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, the ultraviolet cut film 2 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the ultraviolet cut film 2 is usually 100 ° C. or higher and 350 ° C. or lower.

  Moreover, it is preferable that the ultraviolet cut film 2 is high in flexibility, has good adhesion to an adjacent film, and can cut water vapor and oxygen.

  The material which comprises the ultraviolet cut film 2 is arbitrary if the intensity | strength of an ultraviolet-ray can be weakened. Examples of the material include films formed by blending an ultraviolet absorber with an epoxy, acrylic, urethane, or ester resin. Further, a film in which a layer of an ultraviolet absorbent dispersed or dissolved in a resin (hereinafter referred to as “ultraviolet absorbing layer” as appropriate) is formed on a base film may be used.

  Examples of the ultraviolet absorber that can be used include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ones. In addition, a ultraviolet absorber may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio. As described above, a film in which an ultraviolet absorbing layer is formed on a base film can also be used as the ultraviolet absorbing film. Such a film can be produced, for example, by applying a coating solution containing an ultraviolet absorber on a substrate film and drying it.

  Although the material of a base film is not specifically limited, For example, polyester is mentioned at the point from which the balance of heat resistance and a softness | flexibility is obtained.

  Examples of specific products of the ultraviolet cut film 2 include cut ace (MKV Plastic Co., Ltd.). In addition, the ultraviolet cut film 2 may be formed with 1 type of material, and may be formed with 2 or more types of materials.

  Further, the ultraviolet cut film 2 may be formed of a single layer film, but may be a laminated film including two or more layers. The thickness of the ultraviolet cut film 2 is not particularly limited, but is usually 5 μm or more and 200 μm or less.

  Although the ultraviolet cut film 2 should just be provided in the position which covers at least one part of the light-receiving surface 6a of the solar cell element 6, Preferably it is provided in the position which covers all the light-receiving surfaces 6a of the solar cell element 6. FIG. However, the ultraviolet cut film 2 may be provided at a position other than the position covering the light receiving surface 6 a of the solar cell element 6.

[4-3. Gas barrier film (3)]
The gas barrier film 3 is a film that prevents permeation of water and oxygen. By covering the solar cell element 6 with the gas barrier film 3, the solar cell element 6 can be protected from water and oxygen, and the power generation capacity can be kept high.

Although the degree of moisture-proof capability required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like, the water vapor transmission rate per unit area (1 m ² ) per day is usually 1 × 10 ^−1. It is preferable that it is below g / m < ² > / day, and there is no restriction | limiting in a minimum.

Although the degree of oxygen permeability required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like, the oxygen permeability per unit area (1 m ² ) per day is usually 1 × 10 ^−. It is preferably ¹ cc / m ² / day / atm or less, and the lower limit is not limited.

  Moreover, it is preferable that the gas barrier film 3 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the gas barrier film 3 also has heat resistance. From this viewpoint, the melting point of the constituent material of the gas barrier film 3 is usually 100 ° C. or higher and 350 ° C. or lower.

  The specific configuration of the gas barrier film 3 is arbitrary as long as the solar cell element 6 can be protected from water. However, since the manufacturing cost increases as the amount of water vapor or oxygen that can permeate the gas barrier film 3 increases, it is preferable to use an appropriate film considering these points comprehensively.

Particularly suitable gas barrier film 3 includes, for example, a film obtained by vacuum-depositing SiO _x on a base film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

  In addition, the gas barrier film 3 may be formed with 1 type of material, and may be formed with 2 or more types of materials. The gas barrier film 3 may be formed of a single layer film, but may be a laminated film including two or more layers.

  The thickness of the gas barrier film 3 is not particularly defined, but is usually 5 μm or more and 200 μm or less.

As long as the gas barrier film 3 covers the solar cell element 6 and can be protected from moisture and oxygen, the formation position is not limited. However, the front surface of the solar cell element 6 (surface on the light receiving surface side, lower surface in FIG. 2) and It is preferable to cover the back surface (the surface opposite to the light receiving surface; the upper surface in FIG. 2). This is because the front and back surfaces of the thin film solar cell 14 are often formed in a larger area than the other surfaces. In this embodiment, the gas barrier film 3 covers the front surface of the solar cell element 6, and a gas barrier film 9 described later covers the back surface of the solar cell element 6. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good.

[4-4. Getter material film (4)]
The getter material film 4 is a film that absorbs moisture and / or oxygen. By covering the solar cell element 6 with the getter material film 4, the solar cell element 6 and the like are protected from moisture and / or oxygen, and the power generation capacity is kept high. Here, unlike the gas barrier film 3 as described above, the getter material film 4 does not prevent moisture permeation but absorbs moisture. By using a film that absorbs moisture, the getter material film 4 captures moisture that slightly enters the space formed by the gas barrier films 3 and 9 when the solar cell element 6 is covered with the gas barrier film 3 or the like. The influence of moisture on the solar cell element 6 can be eliminated.

The degree of moisture absorption capacity of the getter material film 4 is usually 0.1 mg / cm ² or more, and although there is no upper limit, it is usually 10 mg / cm ² or less. Further, when the solar cell element 6 is covered with the gas barrier films 3 and 9 or the like by the getter material film 4 absorbing oxygen, the oxygen that slightly enters the space formed by the gas barrier films 3 and 9 is obtained as the getter material. The film 4 can capture and eliminate the influence of oxygen on the solar cell element 6.

  Furthermore, it is preferable that the getter material film 4 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, the getter material film 4 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the getter material film 4 is usually 100 ° C. or higher and 350 ° C. or lower.

  The material constituting the getter material film 4 is arbitrary as long as it can absorb moisture and / or oxygen. Examples of the material include alkali metal, alkaline earth metal or alkaline earth metal oxides; alkali metal or alkaline earth metal hydroxides; silica gel, zeolitic compounds, magnesium sulfate. And sulfates such as sodium sulfate and nickel sulfate; and organometallic compounds such as aluminum metal complexes and aluminum oxide octylates. Specifically, examples of the alkaline earth metal include Ca, Sr, and Ba. Examples of the alkaline earth metal oxide include CaO, SrO, and BaO. In addition, Zr-Al-BaO and aluminum metal complexes are also included. Specific product names include, for example, OleDry (Futaba Electronics).

  Examples of the substance that absorbs oxygen include activated carbon, silica gel, activated alumina, molecular sieve, magnesium oxide, and iron oxide. In addition, Fe, Mn, Zn, and inorganic salts such as sulfates, chlorides, and nitrates of these metals are also included.

  In addition, the getter material film 4 may be formed of one type of material or may be formed of two or more types of materials. The getter material film 4 may be formed of a single layer film, but may be a laminated film including two or more layers.

The thickness of the getter material film 4 is not particularly specified, but is usually 5 μm or more and 200 μm or less.

  The formation position of the getter material film 4 is not limited as long as it is in the space formed by the gas barrier films 3 and 9, but the front surface of the solar cell element 6 (the surface on the light receiving surface side, the lower surface in FIG. 2). And it is preferable to cover the back surface (surface opposite to the light receiving surface; upper surface in FIG. 2). This is because, in the thin film solar cell 14, the front and back surfaces are often formed in a larger area than the other surfaces, and therefore moisture and oxygen tend to enter through these surfaces. From this viewpoint, the getter material film 4 is preferably provided between the gas barrier film 3 and the solar cell element 6. In this embodiment, the getter material film 4 covers the front surface of the solar cell element 6, a getter material film 8 described later covers the back surface of the solar cell element 6, and the getter material films 4 and 8 are respectively the solar cell element 6 and the gas barrier film 3. , 9 are located between them. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good.

[4-5. Encapsulant (5)]
The sealing material 5 is a film that reinforces the solar cell element 6. Since the solar cell element 6 is thin, the strength is usually weak, and thus the strength of the thin film solar cell tends to be weak. However, the strength can be maintained high by the sealing material 5.

  Moreover, it is preferable that the sealing material 5 has high strength from the viewpoint of maintaining the strength of the thin-film solar cell 14. The specific strength is related to the strength of the weatherproof protective film 1 other than the sealing material 5 and the strength of the back sheet 10 and is generally difficult to define, but the thin film solar cell 14 as a whole has good bending workability. However, it is desirable to have a strength that does not cause peeling of the bent portion.

  Moreover, it is preferable that the sealing material 5 permeate | transmits visible light from a viewpoint which does not prevent the light absorption of the solar cell element 6. FIG. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.

  The thickness of the sealing material 5 is not particularly specified, but is usually 2 μm or more and 700 μm or less.

  The T-type peel adhesion strength of the sealing material 5 to the substrate is usually 1 N / inch or more and usually 2000 N / inch or less. It is preferable that the T-type peel adhesive strength is 1 N / inch or more in terms of ensuring the long-term durability of the module. It is preferable that the T-type peel adhesive strength is 2000 N / inch or less in that the base material, the barrier film, and the adhesive can be separated and discarded when the solar cell is discarded. The T-type peel adhesion strength is measured by a method according to JIS K6854.

  The constituent material of the sealing material 5 is not particularly limited as long as it has the above characteristics, but sealing of organic / inorganic solar cells, sealing of organic / inorganic LED elements, sealing of electronic circuit boards, etc. In general, a sealing material generally used can be used.

  Specifically, a thermosetting resin composition or a thermoplastic resin composition and an active energy ray curable resin composition can be mentioned. The active energy ray-curable resin composition is, for example, a resin that is cured by ultraviolet rays, visible light, electron beams, or the like. More specifically, an ethylene-vinyl acetate copolymer (EVA) resin composition, a hydrocarbon resin composition, an epoxy resin composition, a polyester resin composition, an acrylic resin composition, and a urethane resin composition. Or a silicon-based resin composition, etc., depending on the main chain, branched chain, terminal chemical modification of each polymer, adjustment of molecular weight, additives, etc., thermosetting, thermoplastic and active energy ray curable, etc. The characteristics are expressed.

  Moreover, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the sealing material 5 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 5 is usually 100 ° C. or higher and 350 ° C. or lower.

The density of the constituent material for sealing material in the sealing material 5 is preferably 0.80 g / cm ³ or more, and there is no upper limit. The measurement and evaluation of density can be performed by a method based on JIS K7112.

  Although there is no restriction | limiting in the position which provides the sealing material 5, Usually, it provides so that the solar cell element 6 may be inserted | pinched. This is for reliably protecting the solar cell element 6. In this embodiment, the sealing material 5 and the sealing material 7 are provided on the front surface and the back surface of the solar cell element 6, respectively.

[4-6. Solar cell element (6)]
The solar cell element 6 is the same as the photoelectric conversion element 107 described above. That is, the thin-film solar cell 14 can be manufactured using the photoelectric conversion element 107.

  Although only one solar cell element 6 may be provided for each thin film solar cell 14, usually two or more solar cell elements 6 are provided. The specific number of solar cell elements 6 may be set arbitrarily. When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are often arranged in an array.

  When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are usually electrically connected to each other, and electricity generated from the connected group of solar cell elements 6 is taken out from a terminal (not shown). At this time, the solar cell elements are usually connected in series in order to increase the voltage.

  Thus, when connecting the solar cell elements 6, it is preferable that the distance between the solar cell elements 6 is small, and by extension, the gap between the solar cell element 6 and the solar cell element 6 is preferably narrow. This is because the light receiving area of the solar cell element 6 is widened to increase the amount of received light, and the amount of power generated by the thin film solar cell 14 is increased.

[4-7. Encapsulant (7)]
The sealing material 7 is a film similar to the sealing material 5 described above, and the same material as the sealing material 7 can be used in the same manner except that the arrangement position is different. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[4-8. Getter material film (8)]
The getter material film 8 is the same film as the getter material film 4 described above, and the same material as the getter material film 4 can be used as necessary, except for the arrangement position. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[4-9. Gas barrier film (9)]
The gas barrier film 9 is the same film as the gas barrier film 3 described above, and the same material as the gas barrier film 9 can be used as necessary except that the arrangement position is different. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[4-10. Back sheet (10)]
The back sheet 10 is the same film as the weather-resistant protective film 1 described above, and the same material as the weather-resistant protective film 1 can be used in the same manner except that the arrangement position is different. In addition, if the back sheet 10 is difficult to permeate water and oxygen, the back sheet 10 can also function as a gas barrier layer. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[4-11. Dimensions]
The thin film solar cell 14 of the present embodiment is usually a thin film member. Thus, by forming the thin film solar cell 14 as a film-like member, the thin film solar cell 14 can be easily installed in a building material, an automobile, an interior, or the like. The thin-film solar cell 14 is light and difficult to break, and thus a highly safe solar cell can be obtained and can be applied to a curved surface, so that it can be used for more applications. Since it is thin and light, it is preferable in terms of distribution such as transportation and storage. Furthermore, since it is in the form of a film, it can be manufactured in a roll-to-roll manner, and a significant cost cut can be achieved.

  Although there is no restriction | limiting in the specific dimension of the thin film solar cell 14, The thickness is usually 300 micrometers or more and 3000 micrometers or less.

[4-12. Production method]
Although there is no restriction | limiting in the manufacturing method of the thin film solar cell 14, For example, as a manufacturing method of the solar cell of the form of FIG. 2, after producing the laminated body shown by FIG. 2, the method of performing a lamination sealing process is mentioned. . Since the solar cell element of this embodiment is excellent in heat resistance, it is preferable in that deterioration due to the laminate sealing step is reduced.

  The laminate production shown in FIG. 2 can be performed using a known technique. The method of the laminate sealing step is not particularly limited as long as the effects of the present invention are not impaired, but for example, wet lamination, dry lamination, hot melt lamination, extrusion lamination, coextrusion molding lamination, extrusion coating, photocuring adhesive Laminate, thermal laminate, etc. are mentioned. Among them, a laminating method using a photo-curing adhesive having a proven record in organic EL device sealing, a hot melt laminate or a thermal laminate having a proven record in solar cells is preferable, and a hot melt laminate or a thermal laminate is a sheet-like sealing material. It is more preferable at the point which can be used.

  The heating temperature in the laminate sealing step is usually 130 ° C or higher, preferably 140 ° C or higher, and is usually 180 ° C or lower, preferably 170 ° C or lower. The heating time in the laminate sealing step is usually 10 minutes or longer, preferably 20 minutes or longer, and is usually 100 minutes or shorter, preferably 90 minutes or shorter. The pressure in the laminate sealing step is usually 0.001 MPa or more, preferably 0.01 MPa or more, and usually 0.2 MPa or less, preferably 0.1 MPa or less. By setting the pressure within this range, sealing can be performed reliably, and the reduction of the film thickness due to the protrusion of the sealing materials 5 and 7 from the end portion and overpressurization can be suppressed, thereby ensuring dimensional stability. In addition, what connected two or more solar cell elements 6 in series or in parallel can be manufactured similarly to the above.

[4-13. Application]
There is no restriction | limiting in the use of the solar cell which concerns on this invention, especially the thin film solar cell 14 mentioned above, It can use for arbitrary uses. Examples of fields to which organic thin film solar cells are applied include building material solar cells, automotive solar cells, interior solar cells, railroad solar cells, marine solar cells, airplane solar cells, spacecraft solar cells, A solar cell for home appliances, a solar cell for mobile phones, a solar cell for toys, and the like.

The solar cell according to the present invention, in particular, a thin film solar cell may be used as it is, or a solar cell may be installed on a substrate and used as a solar cell module. For example, as schematically shown in FIG.
What is necessary is just to prepare the solar cell module 13 provided with the thin film solar cell 14 on the base material 12, and to install and use this in a place of use. That is, the solar cell module 13 can be manufactured using the thin film solar cell 14. As a specific example, when a building material plate is used as the base material 12, a solar cell panel can be produced as the solar cell module 13 by providing the thin film solar cell 14 on the surface of the plate material.

  The substrate 12 is a support member that supports the thin film solar cell 14. Examples of the material for forming the substrate 12 include inorganic materials such as glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine. Organic materials such as resin, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate and polynorbornene; paper materials such as paper and synthetic paper; metals such as stainless steel, titanium and aluminum; Examples thereof include composite materials such as those obtained by coating or laminating a surface of a metal such as stainless steel, titanium, and aluminum to impart insulation.

  In addition, 1 type may be used for the material of a base material, and 2 or more types may be used together by arbitrary combinations and a ratio. Moreover, carbon fiber may be included in these organic materials or paper materials to reinforce the mechanical strength. When the example of the base material 12 is given, Alpolic (registered trademark; manufactured by Mitsubishi Plastics) and the like may be mentioned.

  Although there is no restriction | limiting in the shape of the base material 12, Usually, a board | plate material is used. Moreover, what is necessary is just to set the material of the base material 12, a dimension, etc. arbitrarily according to the use environment. This solar cell panel can be installed on the outer wall of a building.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, it cannot be overemphasized that this invention is not limited only to a following example.

(Measurement of residual elongation)
The residual elongation (A) (%) is measured by measuring the length (B) of the base material at room temperature after heat treatment under each condition, and comparing it with the length (C) before heat treatment. (%) = (BC) ÷ C × 100. When there was no change in the length of the base material of the organic solar cell, it was set to 0%.
(Photoelectric conversion efficiency)
The photoelectric conversion efficiency was measured by the method described in the section of the photoelectric conversion characteristics.

<Example 1>
Zinc oxide is wet-coated on a PEN-lower electrode laminate (with a transmittance of 80% or more and a sheet resistance of 15Ω / □ or less) (glass transition temperature Tg of 155 ° C. of the base material) in which a lower electrode is laminated on a 50 μm thick PEN substrate. Was laminated.
Furthermore, the P3HT: C60 bisindene adduct was laminated by wet coating, and PEDOT: PSS was laminated by wet coating.
The laminated body thus obtained was subjected to heat treatment at 120 ° C. for 10 minutes using an oven. The heat treatment was performed while applying a tensile stress of 2.6 N / mm ² .
The silver electrode was laminated | stacked on the laminated body which heat-processed by vacuum vapor deposition, and the organic solar cell 1 was obtained.
When the residual elongation rate of the organic solar cell 1 was measured, the length of the base material was 39.69 mm, and the length before the heat treatment was 39.53 mm, which was 0.4%.
When the operation of the organic solar cell 1 was confirmed, it operated well with a photoelectric conversion efficiency of 3.0%.

<Comparative Example 1>
An organic solar cell 2 was obtained in the same manner as in Example 1 except that the temperature of the heat treatment was 100 ° C. for 10 minutes.
When the residual elongation rate of the organic solar cell 2 was measured, the length of the base material was 39.45 mm, and the length before the heat treatment was 39.43 mm, which was 0.05%.
When the operation of the organic solar cell 2 was confirmed, the photoelectric conversion efficiency was 2.5%.

<Comparative example 2>
An organic solar cell 3 was obtained in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C. for 10 minutes.
When the residual elongation rate of the organic solar cell 3 was measured, the length of the base material was 39.94 mm, and the length before the heat treatment was 39.30 mm, which was 1.6%.
When the operation of the organic solar cell 3 was confirmed, the photoelectric conversion efficiency was 2.5%.

<Example 2>
An organic solar cell 4 was obtained in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C. for 10 minutes and the tensile stress during the heat treatment was 0.87 N / mm ² .
When the residual elongation rate of the organic solar cell 4 was measured, the length of the base material was 39.90 mm, and the length before the heat treatment was 39.70 mm, which was 0.5%.
When the operation of the organic solar battery 4 was confirmed, the photoelectric conversion efficiency was 3.0%.

DESCRIPTION OF SYMBOLS 101 Cathode 102 Electron taking-out layer 103 Active layer 104 Hole taking-out layer 105 Anode 106 Base material 107 Photoelectric conversion element 1 Weatherproofing protective film 2 UV cut film 3,9 Gas barrier film 4,8 Getter material film 5,7 Sealing material 6 Solar cell element 10 Back sheet 12 Base material 13 Solar cell unit 14 Thin film solar cell

Claims (4)

In the method for producing an organic thin-film solar cell having a coating step of forming a layer by coating on at least a substrate,
Including a heating step of heating the laminate after the coating step to a temperature higher than the glass transition temperature Tg-50 ° C. of the base material,
The manufacturing method characterized by the residual elongation rate of a base material being 1.5% or less.   The method according to claim 1, wherein the substrate is a resin.   The method according to claim 2, wherein the resin is transparent.   The method according to claim 1, wherein the method is performed by roll-to-roll.

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