JP2013165169A - Organic photoelectric conversion element, method for manufacturing the same, organic solar cell, organic solar cell module, supply device, and film deposition apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and safely manufacture an organic thin-film solar cell having high photoelectric conversion efficiency.SOLUTION: A method for manufacturing an organic photoelectric conversion element including at least a pair of electrodes and an organic active layer between the electrodes includes a film deposition step of depositing the organic active layer by a wet deposition method. The film deposition step is performed under an environment in which an oxygen concentration is 18 to 22 vol.% inclusive and the following condition (1) or (2) is satisfied. (1) A sulfur oxide concentration is 1.2 μg/mor less. (2) A nitrogen oxide concentration is 2.5 μg/mor less.

Description

  The present invention relates to an organic photoelectric conversion element and a manufacturing method thereof, an organic solar battery, an organic solar battery module, a supply device, and a film forming device.

  An organic thin film solar cell has an organic active layer containing a p-type semiconductor compound and an n-type semiconductor compound. In Non-Patent Document 1, since this organic active layer is vulnerable to moisture and oxygen, the organic thin-film solar cell in which the organic active layer is formed in the atmosphere deteriorates in characteristics, and in order to avoid characteristic deterioration, a nitrogen atmosphere The formation of an organic active layer is described below. Patent Document 1 describes a method for manufacturing an organic thin-film solar cell in which an organic active layer is formed in an air atmosphere in which moisture and ozone are suppressed to a predetermined concentration or less.

JP 2011-124281 A

Latest Technology of Organic Solar Cells II (CMC Publishing, 2009, Satoshi Uehara, Satoshi Yoshikawa)

  When the organic active layer is formed in a nitrogen atmosphere that does not contain moisture and oxygen as in the method described in Non-Patent Document 1, it is necessary to use an apparatus in which the inside and the outside are cut off, such as a glove box. . Therefore, when manufacturing an organic thin-film solar cell by the method of a nonpatent literature 1, the bigger installation was needed and there existed a problem that manufacturing cost increased. Further, when using a large substrate or using a continuous process such as roll-to-roll, it is difficult to use the method described in Non-Patent Document 1.

  The method described in Patent Document 1 also requires a device for controlling the moisture and ozone in the air, and requires a larger facility, resulting in an increase in manufacturing cost. Furthermore, since the moisture in the air is kept below a certain concentration, there is a problem that static electricity is likely to occur. The generated static electricity ignites the organic solvent used in film formation, and there is a possibility that a flammable explosion will occur.

  An object of the present invention is to easily and safely manufacture an organic thin film solar cell with high photoelectric conversion efficiency.

  In light of the above circumstances, the present inventors have intensively studied a method for manufacturing an organic thin film solar cell easily and safely, and as a result, the conversion efficiency of the organic photoelectric conversion element is reduced by reducing specific components in the film forming environment. The present invention has been completed. That is, the gist of the present invention is as follows.

[1] A method for producing an organic photoelectric conversion device having at least a pair of electrodes and an organic active layer between the electrodes,
Including a film forming step of forming the organic active layer by a wet film forming method,
The method for producing an organic photoelectric conversion element, wherein the film forming step is performed in an environment where an oxygen concentration is 18% by volume or more and 22% by volume or less and satisfies the following (1) or (2).
(1) The sulfur oxide concentration is 1.2 μg / m ³ or less.
(2) Nitrogen oxide concentration is 2.5 μg / m ³ or less.
[2] The method for producing an organic photoelectric conversion element according to [1], wherein the film forming step is performed in an environment satisfying the conditions (1) and (2).
[3] The method for producing an organic photoelectric conversion element according to [1] or [2], wherein the material of the organic active layer contains at least one type of polymer p-type semiconductor compound.
[4] An organic photoelectric conversion element manufactured by the method for manufacturing an organic photoelectric conversion element according to any one of [1] to [3].
[5] The organic photoelectric conversion element according to [4], which is an organic solar battery.
[6] An organic solar cell module comprising the organic photoelectric conversion element according to [4].
[7] A supply device for supplying outside air to a film forming apparatus for forming an organic active layer of an organic photoelectric conversion element by a wet film forming method, and sulfur oxide in the outside air supplied to the film forming apparatus Or the supply apparatus characterized by including the removal means which removes nitrogen oxides.
[8] The supply device according to [7];
A housing for receiving outside air supplied from the supply device;
A film forming means disposed in the housing and forming an organic active layer of the organic photoelectric conversion element by a wet film forming method;
A film forming apparatus comprising:

  An organic thin film solar cell with high photoelectric conversion efficiency can be manufactured easily and safely.

It is sectional drawing which shows typically the structure of the photoelectric conversion element as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell module as one Embodiment of this invention. It is sectional drawing which shows typically the film-forming apparatus as one Embodiment of this invention.

  Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. It is not specified in the contents.

  Below, the manufacturing method of the organic photoelectric conversion element which has at least a pair of electrode and organic active layer between this electrode based on this invention is demonstrated. This method for producing an organic photoelectric conversion element includes a film forming step of forming an organic active layer by a wet film forming method. This film forming process will be described in detail below.

<1. Deposition environment>
In the method for manufacturing a photoelectric conversion element according to the present invention, the film forming step is performed in an environment where the oxygen concentration is 18% by volume or more and 22% by volume or less and the following condition (1) or (2) is satisfied.
(1) The sulfur oxide concentration is below a predetermined concentration.
(2) The nitrogen oxide concentration is below a predetermined concentration.

  In order to improve the conversion efficiency of the obtained photoelectric conversion element, it is preferable to satisfy both of the above conditions (1) and (2).

[1.1 Sulfur oxide concentration]
In the present invention, the sulfur oxide concentration in the environment in which the deposition process takes place is usually 2.2μg / ^{m 3} or less, preferably 1.2 ug / ^{m 3} or less. It is preferable that the sulfur oxide concentration be in this range in that the photoelectric conversion efficiency of the obtained photoelectric conversion element can be improved.

Measurement method Sulfur oxide in the environment is derived from fossil fuel combustion and volcanic gas, and the concentration of sulfur oxide can be measured, for example, by ion chromatography. Specifically, the gas to be measured is collected for 2 hours by passing it through water at a rate of 1.5 L / min, and analyzed by an ion chromatograph analyzer DX500 type (manufactured by DIONEX). Quantify the sulfur oxide concentration in the gas. The detection limit by this method is 0.1 μg / m ³ .

-Reason for controlling sulfur oxide concentration In the present invention, by performing the film forming process in an environment with a lower sulfur oxide concentration, the film forming process is performed in an environment with a higher sulfur oxide concentration. Thus, it has been found that the conversion efficiency of the obtained photoelectric conversion element is improved.

This may be because the reaction with the active layer of sulfur oxide in the environment is prevented. Sulfur oxide is usually contained in the atmosphere at about 50 to 1700 μg / m ³ . It is known that sulfur oxides react with moisture in the atmosphere to become sulfuric acid, which is an oxidant. Moreover, sulfur dioxide and sulfur trioxide, which are types of sulfur oxides, function as a reducing agent and an oxidizing agent, respectively. The properties of the organic compound, such as ionization potential, electron affinity, and carrier mobility, are changed when the organic compound that constitutes the organic photoelectric conversion element is oxidized or reduced by the action of the oxidizing agent or the reducing agent. I think that. Such a component serves as a trap site for charges, and thus can inhibit the transport of the generated charges. As a result, when the film forming process is performed in an environment with a higher sulfur oxide concentration, it is considered that the short circuit current and the fill factor are reduced, and the photoelectric conversion efficiency is lowered.

  In addition, it is considered that an acid such as sulfuric acid is mixed into the organic layer of the organic photoelectric conversion element, thereby causing quenching of charges moving in the organic layer. It is considered that the change in the carrier balance in the organic layer caused the reduction in the efficiency of the organic photoelectric conversion element when the film forming process is performed in an environment having a higher sulfur oxide concentration.

  By performing the film-forming process in an environment where the sulfur oxide concentration is lower, it is possible to avoid the generation of quenchers due to the deterioration of organic compounds and the mixing of acids, and the conversion efficiency of the obtained photoelectric conversion element is improved. Conceivable.

[1.2 Nitrogen oxide concentration]
In the present invention, the nitrogen oxides concentration in the environment in which the film-forming step is carried out is usually 3.1μg / ^{m 3} or less, preferably 2.5 [mu] g / ^{m 3} or less. It is preferable that the nitrogen oxide concentration be in this range in that the photoelectric conversion efficiency of the obtained photoelectric conversion element can be improved.

Measurement method Nitrogen oxides in the environment are derived from the combustion of fossil fuels, and the concentration of nitrogen oxides can be measured, for example, by ion chromatography. Specifically, the gas to be measured is collected for 2 hours by passing it through water at a rate of 1.5 L / min, and this is analyzed by using an ion chromatograph analyzer DX500 type (manufactured by DIONEX). The nitrogen oxide concentration in the gas is quantified. The detection limit by this method is 0.1 μg / m ³ .

・ Reason for controlling nitrogen oxides In the present invention, by performing the film forming process in an environment having a lower nitrogen oxide concentration, the film forming process is performed in an environment having a higher nitrogen oxide concentration. It has been found that the conversion efficiency of the obtained photoelectric conversion element is improved.

This may be because the reaction with the active layer of sulfur oxide in the environment is prevented. Although nitrogen oxides are usually contained in the atmosphere at about 70 to 5400 μg / m ³ . Nitrogen oxides are known to react with moisture in the atmosphere to form nitric acid, a powerful oxidant. It is considered that the organic compound constituting the organic photoelectric conversion element is oxidized by the action of the oxidizing agent, and the unique characteristics of the organic compound, such as ionization potential, electron affinity, and carrier mobility, are changed. Such a component serves as a trap site for charges, and thus can inhibit the transport of the generated charges. As a result, when the film forming process is performed in an environment where the nitrogen oxide concentration is higher, it is considered that the short circuit current and the fill factor are reduced and the photoelectric conversion efficiency is lowered.

  In addition, nitrogen dioxide, which is a kind of nitrogen oxide and is a radical molecule having unpaired electrons, is considered to cause quenching of charges moving in the organic layer when mixed into the organic layer of the organic photoelectric conversion element. It is done. It is considered that the change in the carrier balance in the organic layer caused the reduction in efficiency and the life of the organic photoelectric conversion element when the film forming process is performed in an environment with a higher nitrogen oxide concentration.

  By performing the film forming process in an environment where the concentration of nitrogen oxides is lower, it is possible to avoid the generation of quenchers due to the deterioration of organic compounds and the mixing of acids, and the conversion efficiency of the obtained photoelectric conversion element is improved. Conceivable.

[1.3 Oxygen concentration]
The oxygen concentration in the environment where the film forming process is performed is arbitrary. For example, the oxygen concentration may be 1% by volume or more, or 10% by volume or more. That is, the oxygen concentration in the environment in which the film forming process is performed may be equivalent to the oxygen concentration in the atmosphere. It is preferable that the oxygen concentration in the environment in which the film forming process is performed is equivalent to the oxygen concentration in the atmosphere because the apparatus for performing the film forming process can be simplified. For example, the oxygen concentration can be 18 volume% or more and 22 volume% or less.

  In the present invention, the photoelectric conversion element obtained by performing the film forming step in an environment where the oxygen concentration is equivalent to that in the atmosphere is obtained by performing the film forming step in an environment where the oxygen concentration is 5 ppm or less. It has been found that the conversion efficiency is equivalent to that of the obtained photoelectric conversion element. When a film forming process is performed in an environment where the oxygen concentration is extremely low, a special apparatus such as a glove box is required. In the film forming process according to the present invention, a filter for removing nitrogen oxides or sulfur oxides It is sufficient to have a device such as

  There are several methods for measuring the oxygen concentration, but the method is not particularly limited. For example, a galvanic cell type that measures from the current value of the oxidation-reduction reaction by oxygen, a magnetic pressure type that measures using strong paramagnetism of oxygen, and a zirconia type that measures from electromotive force due to ionic conduction of oxygen are included.

[1.4 Humidity]
The humidity in the environment where the film forming process is performed is arbitrary. For example, the relative humidity may be 1% or more, or 10% or more. Moreover, although the upper limit of relative humidity is not specifically limited, For example, 90% or less may be sufficient and 60% or less may be sufficient. That is, the humidity in the environment in which the film forming process is performed may be equal to the humidity in the atmosphere. It is preferable that the humidity in the environment in which the film forming process is performed is equal to the humidity in the atmosphere because the apparatus for performing the film forming process can be simplified.

  In the present invention, the photoelectric conversion element obtained by performing the film forming process in an environment where the humidity is equivalent to that in the atmosphere performs the film forming process in an environment where the relative humidity is 0.1% or less. It was found that the conversion efficiency is equivalent to that of the photoelectric conversion element obtained by the above. When the film forming process is performed in an environment with extremely low humidity, a special apparatus such as a glove box is required. In the film forming process according to the present invention, a filter for removing nitrogen oxides or sulfur oxides is required. It would be sufficient if there was such a device.

  Relative humidity is a percentage of the amount of water vapor in the environment and the amount of saturated water vapor at that temperature. The relative humidity measuring instrument can be appropriately selected according to the amount of water vapor in the atmosphere to be measured. Usually, an electric capacity type hygrometer (for example, testo608-H2 manufactured by testo) can be used. When the amount of water vapor in the atmosphere is low, an electrolytic moisture meter (manufactured by MBRAUM, MB MO-SE-1) can be used.

<2. Deposition system>
FIG. 4 shows an example of a film forming apparatus used for performing the film forming process according to the present invention. A film forming apparatus 20 shown in FIG. 4 is an apparatus for forming an organic active layer of an organic photoelectric conversion element by a wet film forming method. The film forming apparatus 20 includes a housing 21, an air purification unit 22, and a blower 23. The air purifying means 22 can function as a removing means for removing sulfur oxides or nitrogen oxides in the outside air supplied to the housing 21 and as a supply device for supplying outside air to the housing 21. A supply method including a step of removing sulfur oxides or nitrogen oxides from the outside air by using the air purification means 22 and a step of supplying outside air from which sulfur oxides or nitrogen oxides have been removed to the housing 21. Can be realized.

  The film forming process according to the present invention is performed in the housing 21. That is, an apparatus (film forming means) for forming an organic active layer of the organic photoelectric conversion element by a wet film forming method is provided in the housing 21. In the housing 21, an organic active layer is formed by coating. For example, a substrate for forming an organic active layer (for example, an electrode, and a buffer layer (a hole extraction layer or an electron extraction layer) formed on the substrate as necessary) is inserted into the housing 21, and this An organic active layer is formed by forming an organic active layer on a substrate by a coating film forming method.

[2.1 Housing 21]
The housing 21 is configured to receive outside air supplied from the air purification means 22 and the blower 23. Further, as shown in the lower part of FIG. 4, the housing 21 may further include a discharge part for discharging the received outside air. For example, the discharge portion may be an opening for inserting a substrate on which the organic active layer is formed in the housing 21 or for taking out the substrate on which the organic active layer is formed. In this case, it is preferable that the housing 21 continuously receives the outside air supplied from the air purification means 22 and the blower 23. In this case, since the inside of the housing 21 is slightly pressurized, it is possible to prevent sulfur oxide or nitrogen oxide from flowing into the housing 21 from the opening. Such a configuration is particularly advantageous when using a continuous process, such as a roll-to-roll process, in which the substrate is continuously inserted into and removed from the housing 21.

[2.2 Air purification means 22]
The air purification means 22 removes sulfur oxides or nitrogen oxides in the air supplied into the housing 21. The air purifying means 22 does not need to remove all sulfur oxides or nitrogen oxides, and reduces the concentration of sulfur oxides or nitrogen oxides in the air supplied into the housing 21 to a predetermined value or less. do it. Thus, the sulfur oxide concentration or the nitrogen oxide concentration in the air in the housing 21 can be set to a predetermined value or less.

  The air purification means is not particularly limited as long as it can remove sulfur oxides or nitrogen oxides in the air, and examples thereof include chemical filters, activated carbon for gas phase adsorption, and water. Among these, it is particularly preferable to use a chemical filter from the viewpoint of removal efficiency of sulfur oxides or nitrogen oxides. Among these, one type may be used alone, or two or more types may be used in combination. The air purification means may further include a filter for capturing fine particles such as a HEPA filter. Hereinafter, these methods will be described in detail.

-Chemical filter The chemical filter has a function of removing specific components such as inorganic gas components from the air. As the air purification means according to the present invention, a chemical filter for removing sulfur oxides or nitrogen oxides is used. By passing air through a chemical filter, sulfur oxides or nitrogen oxides can be removed. As the chemical filter, a substance having an adsorption function, such as activated carbon or activated alumina, to which a component for removing a specific gas is welded can be used.

  The chemical filter used is not particularly limited as long as the effects of the present invention are not impaired. For example, chemical guard (manufactured by NICHIAS), pure light filter (manufactured by Japan Puretec), puresmel (manufactured by Nippon Inorganic), TIOS Takasago Thermal Chemical Co., Ltd.).

  The use of a chemical filter is preferable in that the air permeability of the chemical filter and the adsorption and collection performance of gaseous impurity components are high, and the cost of the chemical filter is low and it is easy to obtain.

-Activated carbon for gas phase adsorption Activated carbon for gas phase adsorption is a fine pore of 1 to 20 nm that has been subjected to chemical or physical treatment in order to increase adsorption capacity for the purpose of separating, removing, and purifying specific substances. It is carbon which has many. Normally, 90% or more of the constituent material of the activated carbon for gas phase adsorption is carbon. As the air purification means according to the present invention, activated carbon for gas phase adsorption that removes sulfur oxides or nitrogen oxides is used. Sulfur oxides or nitrogen oxides can be removed by passing air through gas phase adsorption activated carbon, for example, through a column filled with gas phase adsorption activated carbon.

  The activated carbon for gas phase adsorption to be used is not particularly limited as long as the effects of the present invention are not impaired. , Activated carbon (Futamura Chemical Co., Ltd.), and the like.

  The use of activated carbon for gas phase adsorption is preferable in that the adsorption speed is high because physical adsorption is performed, and the adsorption performance hardly depends on the flow rate of the introduced air. Further, it is preferable in that the activated carbon for gas phase adsorption that has been used once can be reused, the cost is low, and it is easy to obtain.

-Water Sulfur oxides or nitrogen oxides can be removed by passing air through water. Moreover, sulfur oxides or nitrogen oxides can be removed by spraying water on the flowing air, or bringing the air and water into countercurrent contact.

  Although there is no restriction | limiting in particular in the water to be used, It is preferable to use demineralized water, the water which passed the ion exchange resin, the pure water, or the ultrapure water at the point which a sulfur oxide, a nitrogen oxide, etc. are easy to remove.

[2.3 Blower 23]
The blower 23 sends outside air to the air purification means 22 and supplies the outside air that has passed through the air purification means 22 to the housing 21. The type of the blower 23 is not particularly limited, and can be, for example, a normal air pump. In FIG. 4, the blower 23 is installed in front of the air purification means 22, but the blower 23 may be installed between the air purification means 22 and the housing 21, or an air discharge unit from the housing 21. May be provided.

  By using the film forming apparatus 20 described above, the air whose sulfur oxide concentration or nitrogen oxide concentration is reduced by the air purifying means is supplied to the housing 21, and an environment for the film forming process can be realized. . Thus, the environment for the film forming process according to the present invention can be realized by a simple apparatus mainly composed of the blower 23, the air purification means 22, and the housing 21. Further, when the film forming apparatus 20 is used, a larger amount of air can be supplied to the housing than when the glove box is used. This is advantageous in that the drying efficiency of the organic active layer formed by coating can be improved.

  In the embodiment shown in FIG. 4, the air purification means 22 removes sulfur oxides or nitrogen oxides in the outside air and supplies them into the housing 21. However, the air purification means 22 may remove sulfur oxides or nitrogen oxides from the air in the housing 21 and release them again into the housing 21.

<3. Wet deposition method>
There is no particular limitation on the type of wet film forming method used in the film forming process according to the present invention. Examples of wet film forming methods include, for example, spin coating, ink jet, doctor blade, drop casting, reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, wire Examples thereof include a barber coating method, a pipe doctor method, an impregnation / coating method, and a curtain coating method. It is particularly preferable to use the spin coating method because it is easy to form a uniform film.

<4. Organic active layer>
The organic active layer formed in the film forming step according to the present invention usually includes at least one of a p-type semiconductor compound and an n-type semiconductor compound. That is, a p-type semiconductor layer containing a p-type semiconductor compound, an n-type semiconductor layer containing an n-type semiconductor compound, or both may be formed by the film forming process according to the present invention. A hetero layer may be formed. It is preferable that the material of the organic active layer contains at least one polymer p-type semiconductor compound in terms of good coating film forming properties. In particular, a high molecular p-type semiconductor compound having a narrow band gap has a relatively high HOMO energy level, and may be easily damaged by a sulfur compound or a nitrogen compound in a film formation atmosphere. On the other hand, in the present invention, it was discovered that the polymer p-type semiconductor compound is hardly damaged even when oxygen is contained in the film formation atmosphere. Therefore, the film forming process according to the present invention is suitable for forming an organic active layer containing such a polymer p-type semiconductor compound.

  Specifically, a coating solution containing at least one of a p-type semiconductor compound and an n-type semiconductor compound is prepared, and wet deposition is performed in the above-described environment using this coating solution, thereby obtaining a substrate (for example, a substrate). An organic active layer can be formed on an electrode and a buffer layer (a hole extraction layer or an electron extraction layer) or the like as necessary). However, as will be described later, wet film formation can be performed using a coating solution containing a semiconductor compound precursor, and then the semiconductor compound precursor can be converted into a semiconductor compound. As described above, in the present invention, the coating liquid used in the wet film formation in the film formation step includes one containing a semiconductor compound precursor instead of the semiconductor compound.

  Specific examples of the material used for the organic active layer and the solvent of the coating solution will be described later. The characteristics of the organic active layer such as the film thickness will be described later.

<5. Organic photoelectric conversion element>
As an example of the organic photoelectric conversion element according to the present invention, an organic photoelectric conversion element used in a general organic thin film solar cell is shown in FIG. In FIG. 1, the organic photoelectric conversion element 107 includes a substrate 106, an electrode 101, a hole extraction layer 102, an organic active layer 103, an electron extraction layer 104, and an electrode 105 in this order. The electrode 101 is preferably an electrode 101 suitable for collecting holes (hereinafter sometimes referred to as an anode), and the electrode 105 is preferably an electrode suitable for collecting electrons (hereinafter referred to as a cathode). (It may be described) is preferably used. Other layers may be provided between the above-described layers to the extent that the functions of the layers described later are not affected. Further, the substrate 106, the hole extraction layer 102, and / or the electron extraction layer 104 may not be provided depending on the use of the photoelectric conversion element 107. In the example of FIG. 1, the substrate 106 is disposed on the anode 101 side, but the substrate 106 may be disposed on the cathode 105 side.

[5.1 Organic active layer (103)]
In the photoelectric conversion element according to the present invention, the organic active layer 103 refers to a layer in which photoelectric conversion is performed, and includes a p-type semiconductor compound and an n-type semiconductor compound. When the photoelectric conversion element 107 receives light, the light is absorbed by the organic 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.

  The organic active layer 103 may contain an inorganic compound, but more preferably consists of an organic compound. Examples of the layer configuration of the organic active layer include a thin film stacked type in which a p-type semiconductor compound and an n-type semiconductor compound are stacked, or a bulk heterojunction type in which a p-type semiconductor compound and an n-type semiconductor compound are mixed. In the bulk heterojunction type, it is only necessary to have a layer in which both p-type and n-type semiconductor compounds are mixed. In addition, only a p-type semiconductor compound or a layer of only n-type semiconductor compounds may be provided. In terms of photoelectric conversion efficiency, the organic active layer is preferably a bulk heterojunction type.

[5.1.1 Thin film laminated organic active layer]
The thin film stacked organic active layer has a structure in which a p-type semiconductor layer containing a p-type semiconductor compound and an n-type semiconductor layer containing an n-type semiconductor compound are stacked. The thin film stacked organic active layer can be produced by forming a p-type semiconductor layer and an n-type semiconductor layer, respectively. At least one of the p-type semiconductor layer and the n-type semiconductor layer is produced by the film forming process according to the present invention. The other of the p-type semiconductor layer and the n-type semiconductor layer may be formed by another method such as a vapor deposition method. However, it is preferable that both the p-type semiconductor layer and the n-type semiconductor layer are formed by the film forming process according to the present invention in that the conversion efficiency of the photoelectric conversion element can be improved.

[5.1.1.1 p-type semiconductor layer]
The p-type semiconductor layer is a layer containing a p-type semiconductor compound. There is no limitation on the film thickness of the p-type semiconductor layer. However, it is usually 5 nm or more, preferably 10 nm or more, and usually 500 nm or less, preferably 200 nm or less. When the film thickness of the p-type semiconductor layer is 500 nm or less, it is preferable in that the series resistance is lowered. It is preferable that the thickness of the p-type semiconductor layer is 5 nm or more because more light can be absorbed.

  The p-type semiconductor layer is preferably produced by a film forming process according to the present invention. For example, a coating solution containing a p-type semiconductor compound may be prepared and applied. After applying the coating solution, a drying process may be performed by heating or the like.

[5.1.1.2 N-type semiconductor layer]
The n-type semiconductor layer is a layer containing an n-type semiconductor compound. Although there is no special restriction | limiting in the film thickness of an n-type semiconductor layer, Usually, 5 nm or more, Preferably it is 10 nm or more, On the other hand, it is 500 nm or less normally, Preferably it is 200 nm or less. When the film thickness of the n-type semiconductor layer is 500 nm or less, it is preferable in that the series resistance is lowered. It is preferable that the thickness of the n-type semiconductor layer is 5 nm or more because more light can be absorbed.

  The n-type semiconductor layer is preferably produced by a film forming process according to the present invention. For example, a coating solution containing an n-type semiconductor compound may be prepared and this coating solution may be applied. After applying the coating solution, a drying process may be performed by heating or the like.

[5.1.2 Organic active layer of bulk heterojunction type]
The bulk heterojunction organic active layer has a layer (i layer) in which a p-type semiconductor compound and an n-type semiconductor compound are mixed. The i layer has a structure in which the p-type semiconductor compound and the n-type semiconductor compound are phase-separated, carrier separation occurs at the phase interface, and the generated carriers (holes and electrons) are transported to the electrode.

  There is no restriction | limiting in the film thickness of i layer. However, it is usually 5 nm or more, preferably 10 nm or more, and usually 500 nm or less, preferably 200 nm or less. When the film thickness of the i layer is 500 nm or less, it is preferable in that the series resistance is lowered. When the film thickness of the i layer is 5 nm or more, it is preferable in that more light can be absorbed.

  The i layer is preferably formed by the film forming process according to the present invention. For example, a coating solution containing a p-type semiconductor compound and an n-type semiconductor compound may be prepared and applied. The coating liquid containing the p-type semiconductor compound and the n-type semiconductor compound may be prepared by preparing and mixing a solution containing the p-type semiconductor compound and a solution containing the n-type semiconductor compound, respectively. It may be prepared by dissolving the compound and the n-type semiconductor compound.

[5.1.2.1 Additives]
When the i layer is formed by the film forming step according to the present invention, an additive may be further added to the coating solution containing the p-type semiconductor compound and the n-type semiconductor compound. The phase separation structure of the p-type semiconductor compound and the n-type semiconductor compound in the bulk heterojunction organic active layer affects the light absorption process, exciton diffusion process, exciton separation (carrier separation) process, carrier transport process, etc. There is. Therefore, it is considered that good photoelectric conversion efficiency can be realized by optimizing the phase separation structure. When the coating solution contains an additive having volatility different from that of the solvent, a preferable phase separation structure is obtained at the time of forming the organic active layer, and the additive is preferably contained in that the photoelectric conversion efficiency can be improved.

  As an example of an additive, the compound etc. which are described in the international publication 2008/066933 are mentioned, for example. More specific examples of the additive include aromatic compounds such as alkane having a substituent or naphthalene having a substituent. Examples of substituents include aldehyde groups, oxo groups, hydroxy groups, alkoxy groups, thiol groups, thioalkyl groups, carboxyl groups, ester groups, amine groups, amide groups, fluoro groups, chloro groups, bromo groups, iodo groups, halogen groups, A nitrile group, an epoxy group, an aromatic group, an arylalkyl group, etc. are mentioned. There may be one or more, for example two, substituents. A preferred substituent for the alkane is a thiol group or an iodo group. Moreover, as a substituent which an aromatic compound like naphthalene has, Preferably, they are a bromo group or a chloro group.

  Since the additive preferably has a high boiling point, the aliphatic hydrocarbon used as the additive preferably has 6 or more carbon atoms, and more preferably 8 or more carbon atoms. Moreover, since it is preferable that an additive is liquid at normal temperature, carbon number of an aliphatic hydrocarbon has preferable 14 or less, and 12 or less is more preferable. For the same reason, the aromatic hydrocarbon used as an additive usually has 6 or more carbon atoms, preferably 8 or more, more preferably 10 or more, and usually 50 or less, preferably 30 or less, more preferably 20 or less. The number of carbon atoms of the aromatic heterocycle used as an additive is usually 2 or more, preferably 3 or more, more preferably 6 or more, and usually 50 or less, preferably 30 or less, more preferably 20 or less. The boiling point of the additive is usually 100 ° C. or higher, preferably 200 ° C. or higher at normal pressure (1 atm), and is usually 600 ° C. or lower, preferably 500 ° C. or lower.

  The amount of the additive contained in the coating solution containing the p-type semiconductor compound and the n-type semiconductor compound is usually 0.1% by weight or more, preferably 0.5% by weight or more based on the whole coating solution. Moreover, it is 10 weight% or less normally with respect to the whole coating liquid, Preferably it is 3 weight% or less. When the amount of the additive is within this range, a preferable phase separation structure can be obtained while reducing the additive remaining in the organic active layer. As described above, a bulk heterojunction active layer can be formed by applying a coating liquid (ink) containing a p-type semiconductor compound, an n-type semiconductor compound, and, if necessary, an additive.

[5.1.3 Heat treatment of active layer]
After forming the thin film stacked type active layer or after forming the bulk heterojunction type active layer, the obtained layer may be heat-treated (this process may be referred to as a pre-annealing process).

  The temperature in the pre-annealing process is usually 80 ° C. or higher, preferably 100 ° C. or higher, and is usually 200 ° C. or lower, preferably 160 ° C. or lower, more preferably 150 ° C. or lower. By setting the temperature of this pre-annealing treatment step to 100 ° C. or higher, the residual solvent component contained in the organic active layer 103 volatilizes or crystallinity is imparted to the p-type semiconductor compound in the active layer. It is preferable at the point which heat resistance can improve. It is preferable that the temperature of the pre-annealing process is 200 ° C. or lower because the possibility that the organic compound in the active layer is thermally decomposed is reduced. As a heat treatment 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. Moreover, it may be a batch type or a continuous type. In addition, about temperature operation, you may heat-process in steps within the said range.

  The time for the pre-annealing treatment step is usually 1 minute or longer, preferably 3 minutes or longer, and is usually 3 hours or shorter, preferably 1 hour or shorter. The pressure in the pre-annealing process is not particularly limited, and may be any of normal pressure conditions, reduced pressure conditions, and pressurized conditions. The pre-annealing process is preferably performed in the same atmosphere as the film-forming process according to the present invention or in an inert gas atmosphere because the active layer is hardly deteriorated.

[5.1.4 Solvent of coating solution]
Examples of the solvent for the coating solution containing the p-type semiconductor compound, the coating solution containing the n-type semiconductor compound, and the coating solution containing the p-type semiconductor compound and the n-type semiconductor compound include p-type semiconductor compounds and / or n-type. Although it will not specifically limit if a semiconductor compound can be melt | dissolved uniformly, For example, aliphatic hydrocarbons, such as hexane, heptane, octane, isooctane, nonane, or decane; Toluene, xylene, mesitylene, cyclohexylbenzene, chlorobenzene, or orthodi Aromatic hydrocarbons such as chlorobenzene; cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin; lower alcohols such as methanol, ethanol or propanol; acetone, methyl ethyl ketone Aliphatic ketones such as cyclohexane, cyclopentanone or cyclohexanone; aromatic ketones such as acetophenone or propiophenone; esters such as ethyl acetate, butyl acetate or methyl lactate; chloroform, methylene chloride, dichloroethane, trichloroethane, or trichloroethylene Halogen ethers of the above; ethers such as ethyl ether, tetrahydrofuran or dioxane; or amides such as dimethylformamide or dimethylacetamide.

  Among them, aromatic hydrocarbons such as toluene, xylene, mesitylene, cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; cycloaliphatic carbonization such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin Hydrogens; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; halogen hydrocarbons such as chloroform, methylene chloride, dichloroethane, trichloroethane or trichloroethylene; or ethers such as ethyl ether, tetrahydrofuran or dioxane. More preferably, non-halogen aromatic hydrocarbons such as toluene, xylene, mesitylene or cyclohexylbenzene; non-halogen ketones such as cyclopentanone or cyclohexanone; aromatic ketones such as acetophenone or propiophenone; tetrahydrofuran, cyclohexane Alicyclic hydrocarbons such as pentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; or non-halogens such as 1,4-dioxane Aliphatic ethers. Particularly preferred are non-halogen aromatic hydrocarbons such as toluene, xylene, mesitylene or cyclohexylbenzene.

  In addition, as a solvent, 1 type of solvent may be used independently, and arbitrary 2 or more types of solvents may be used together in arbitrary ratios. When two or more solvents are used in combination, it is preferable to combine a low boiling point solvent having a boiling point of 60 to 150 ° C and a high boiling point solvent having a boiling point of 180 to 250 ° C. Examples of combinations of low and high boiling solvents include non-halogen aromatic hydrocarbons and alicyclic hydrocarbons, non-halogen aromatic hydrocarbons and aromatic ketones, ethers and alicyclic carbonization. Examples thereof include hydrogens, ethers and aromatic ketones, aliphatic ketones and alicyclic hydrocarbons, or aliphatic ketones and aromatic ketones. Specific examples of preferred combinations include toluene and tetralin, xylene and tetralin, toluene and acetophenone, xylene and acetophenone, tetrahydrofuran and tetralin, tetrahydrofuran and acetophenone, methyl ethyl ketone and tetralin, methyl ethyl ketone and acetophenone, and the like.

[5.1.5 n-type semiconductor compound]
The n-type semiconductor compound that can be included in the organic active layer 103 is not particularly limited. Specifically, the fullerene compound, a quinolinol derivative metal complex represented by 8-hydroxyquinoline aluminum; naphthalenetetracarboxylic acid diimide or perylenetetra Condensed ring tetracarboxylic acid diimides such as carboxylic acid diimides; perylene diimide derivatives, terpyridine metal complexes, tropolone metal complexes, flavonol metal complexes, perinone derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazole derivatives, benzthiazol derivatives, benzothiadiazole derivatives Oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives Body, benzoquinoline derivatives, bipyridine derivatives, borane derivatives, anthracene, pyrene, total fluoride condensed polycyclic aromatic hydrocarbons such as naphthacene or pentacene; single-walled carbon nanotubes, n-type polymer semiconductor compounds, and the like.

[5.1.5.2.1.2.1 Fullerene Compound]
Although it does not specifically limit as a fullerene compound which the organic active layer 103 can contain, The fullerene compound etc. which are described in the international publication 2011/016430 are mentioned. Specifically, silylmethyl group adduct fullerene compound such as SIMEF or SIMEF2; bisindene adduct fullerene compound such as C ₆₀ (Ind) ₂ or C ₇₀ (Ind) ₂ ; C ₆₀ (QM) ₂ or C ₇₀ (QM) Biskinodimethane adduct fullerene compounds such as ₂ ; and methanofullerene compounds such as C ₆₀ PCBM, C ₇₀ PCBM, C ₆₀ PCBNB, and C ₇₀ PCBNB. For example, commercially available C ₆₀ PCBM, C ₇₀ PCBM, or C ₆₀ PCBNB (Frontier Carbon Co.) can be used.

[5.1.5.2.2 N-alkyl substituted perylene diimide derivatives]
The N-alkyl-substituted perylene diimide derivative that can be included in the organic active layer 103 is not particularly limited, and specifically, International Publication No. 2008/063609, International Publication No. 2009/115513, International Publication No. 2009. / 098250, the international publication 2009/000756 and the international publication 2009/091670 are mentioned. N-alkyl-substituted perylene diimide derivatives are preferable in that they have high electron mobility and absorption in the visible region, and thus contribute to both charge transport and power generation.

[5.1.2.3.2.3 Naphthalenetetracarboxylic acid diimide]
The naphthalenetetracarboxylic acid diimide that can be contained in the organic active layer 103 is not particularly limited, and specifically, International Publication No. 2008/063609, International Publication No. 2007/146250 and International Publication No. 2009/000756. The compounds described are mentioned. Naphthalenetetracarboxylic acid diimide is preferable because it has high electron mobility, high solubility, and excellent coating properties.

[5.1.2.4 n-type polymer semiconductor compound]
The n-type polymer semiconductor compound that can be included in the organic active layer 103 is not particularly limited, but condensed ring tetracarboxylic acid diimides such as naphthalenetetracarboxylic acid diimide and perylenetetracarboxylic acid diimide, perylene diimide derivatives, and benzimidazole Derivative unit, benzoxazole derivative, thiazole derivative, benzothiazole derivative, benzothiadiazole derivative, oxadiazole derivative, thiadiazole derivative, triazole derivative, pyrazine derivative, phenanthroline derivative, quinoxaline derivative, bipyridine derivative and borane derivative And an n-type polymer semiconductor compound.

  Among them, polymers having at least one of borane derivatives, thiazole derivatives, benzothiazole derivatives, benzothiadiazole derivatives, N-alkyl-substituted naphthalenetetracarboxylic acid diimides and N-alkyl-substituted perylene diimide derivatives as constituent units are 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. You may contain 1 type, or 2 or more types of these compounds.

  Specific examples thereof 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. Since n-type polymer semiconductor compounds have absorption in the visible range, they contribute to power generation, have high viscosity, and are excellent in terms of coating properties.

[5.1.6 p-type semiconductor compound]
In the photoelectric conversion element 107 according to the present invention, examples of the p-type semiconductor compound that can be included in the organic active layer 103 include a p-type high molecular semiconductor compound and a p-type low molecular semiconductor compound.

The p-type polymer semiconductor compound is not particularly limited, but specifically, conjugated polymer semiconductors such as polythiophene, polyfluorene, polyphenylene vinylene, polythienylene vinylene, polyacetylene, polyaniline; alkyl groups and other substituents Examples thereof include polymer semiconductors such as substituted oligothiophenes. Moreover, the semiconductor copolymer which copolymerized 2 or more types of monomer units is also mentioned. Conjugated copolymers are described in, for example, Handbook of Conducting Polymers, 3 ^rd Ed. (2 volumes), 2007, Materials Science and Engineering, 2001, 32, 1-40, Pure Appl. Chem. Use a copolymer which can be synthesized by a combination of known copolymers such as 2002, 74, 2031-3044, Handbook of THIOPHENE-BASED MATERIALS (2 volumes), 2009, derivatives thereof, and monomers described therein. Can do. Specific examples of the monomer include thiophene derivatives, imidothiophene derivatives, and dithienosilole derivatives. Among these, the use of an alternating copolymer of an imidothiophene derivative and a dithienosilole derivative is preferable in that the photoelectric conversion efficiency can be further improved.

  One kind of compound or a mixture of plural kinds of compounds may be used. Specific examples of the p-type polymer semiconductor compound include the following, but are not limited thereto.

  The p-type low molecular semiconductor compound is not particularly limited. Specifically, it is a condensed aromatic hydrocarbon such as naphthacene, pentacene, or pyrene; an oligothiophene containing four or more thiophene rings such as α-sexithiophene. A thiophene ring, a benzene ring, a fluorene ring, a naphthalene ring, an anthracene ring, a thiazole ring, a thiadiazole ring, a benzothiazole ring, or a total of four or more; And macrocyclic compounds such as the metal complex. As the compound, compounds described in International Publication No. 2011/016430 can be used.

Examples of the porphyrin compound and its metal complex (X ¹¹ in the figure is CH), the phthalocyanine compound and its metal complex (X ¹¹ in the figure is N) include compounds having the following structures.

^{Here, M 11} represents a metal or two hydrogen atoms, a metal, Cu, Zn, Pb, Mg, other divalent metal such as Co or Ni, 3 or more valences with an axial ligand Metals such as TiO, VO, SnCl ₂ , AlCl, InCl or Si are also included.

X ^{12 to} X ¹⁵ 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 phthalocyanine compounds and metal complexes thereof, preferably 29H, 31H-phthalocyanine, copper phthalocyanine complex, zinc phthalocyanine complex, magnesium phthalocyanine complex, lead phthalocyanine complex, titanium phthalocyanine oxide complex, vanadium phthalocyanine oxide complex, indium phthalocyanine halogen complex, gallium A phthalocyanine halogen complex, an aluminum phthalocyanine halogen complex, a tin phthalocyanine halogen complex, a silicon phthalocyanine halogen complex, or a copper 4,4 ′, 4 ″, 4 ′ ″-tetraaza-29H, 31H-phthalocyanine complex, more preferably Titanium phthalocyanine oxide complex, vanadium phthalocyanine oxide complex, indium phthalocyanine chloro complex, aluminum fluoride Russia is a Nin chloro complexes. In addition, the above kind of compound or a mixture of plural kinds 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. In addition, the above kind of compound or a mixture of plural kinds of compounds may be used.

  As a method for forming a layer containing a p-type low molecular semiconductor compound, there is a method of converting into a p-type low molecular semiconductor compound after forming a layer containing a p-type low molecular semiconductor compound precursor. Here, in order to form the layer containing the p-type low molecular semiconductor compound precursor, the film forming process according to the present invention can be used.

  A semiconductor compound precursor is a substance that changes its chemical structure and is converted into a semiconductor compound by applying an external stimulus such as heating or light irradiation. The semiconductor compound precursor according to the present invention 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 semiconductor compound precursor is 0.1 weight% or more normally, 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 solvent is not particularly limited as long as it can uniformly dissolve or disperse the semiconductor compound precursor. 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, a solvent may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

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

  Moreover, it is preferable that a semiconductor compound precursor is converted into a semiconductor compound with a high yield through a conversion process. At this time, the yield of the semiconductor compound obtained by conversion from the semiconductor compound precursor is arbitrary as long as the performance of the organic photoelectric conversion element is not impaired, but the yield of the semiconductor compound obtained from the semiconductor compound precursor is usually 90. It is at least mol%, preferably at least 95 mol%, more preferably at least 99 mol%.

  The semiconductor compound precursor is not particularly limited as long as it has the above characteristics, but 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 X ¹⁶ and X ¹⁷ represents a group that forms a π-conjugated divalent aromatic ring, Z ¹ -Z ² is a group that can be removed by heat or light, and Z ¹ The π-conjugated compound obtained by elimination of —Z ² represents a pigment molecule. Further, X ¹⁶ and X ¹⁷ which are not a group forming a π-conjugated divalent aromatic ring represent a substituted or unsubstituted ethenylene group.

In the compound represented by the above formula, Z ¹ -Z ² 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 semiconductor compound.

Examples of the compound represented by the above formula include the following. T-Bu represents a t-butyl group. M ¹² represents an atomic group in which a divalent metal atom or a trivalent or higher metal and another atom are bonded.

  As a method for converting the semiconductor compound precursor into the semiconductor compound, a known method can be used.

  The semiconductor compound precursor represented by the above formula may have a structure in which positional isomers exist, and in that case, may consist of a mixture of a plurality of positional isomers. A semiconductor compound precursor composed of a plurality of positional isomers is preferable because it has a higher solubility in a solvent than a semiconductor compound precursor composed of a single isomer component, so that coating film formation is easy. The reason why the solubility is improved when a mixture of multiple positional isomers is used 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. Therefore, it is assumed that the three-dimensional regular intermolecular interaction becomes difficult. In the present invention, the solubility of the precursor mixture composed of a plurality of isomeric compounds 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.

[5.2 Buffer layer (102, 104)]
The photoelectric conversion element 107 according to the present invention preferably further includes one or more buffer layers in addition to the pair of electrodes (101, 105) and the organic active layer 103 disposed therebetween. The buffer layer can be classified into an electron extraction layer 104 and a hole extraction layer 102, and can be provided between the organic active layer 103 and the electrodes (101, 105), respectively. By providing the buffer layer, there are advantages that the mobility of electrons and holes between the active layer and the electrode is increased, and that a short circuit between the electrodes can be prevented.

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

[5.2.1 Electron extraction layer (104)]
The material of the electron extraction layer 104 is not particularly limited as long as it can improve the efficiency of extracting electrons from the organic active layer 103 containing the p-type semiconductor compound and the n-type semiconductor compound to the electrode 101. Specifically, an inorganic compound or an organic compound is mentioned.

[5.2.1.1 Inorganic compounds]
The inorganic compound is preferably an alkali metal salt such as Li, Na, K or Cs; an n-type semiconductor metal oxide such as titanium oxide (TiOx) or zinc oxide (ZnO).

  As the alkali metal salt, a fluoride salt such as LiF, NaF, KF or CsF is preferable. Although the operation mechanism of such a material is unknown, it is conceivable to reduce the work function of the cathode 105 in combination with an electron extraction electrode (cathode 105) such as Al and increase the voltage applied to the inside of the photoelectric conversion element. It is done.

  Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, aluminum oxide, silicon oxide, cerium oxide, lead oxide, zirconium oxide, and gallium oxide. Of these, zinc oxide, titanium oxide or tin oxide is preferable. Moreover, a metal oxide may be used individually by 1 type, or may use 2 or more types together. The metal oxide desirably has a porous (porous) structure.

  Further, the metal oxide is preferably in the form of particles, and the average primary particle size is usually 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more, while usually 100 nm or less, preferably 60 nm or less, more Preferably it is 40 nm or less.

  When the average primary particle size is 5 nm or more, the primary particles of the metal oxide hardly aggregate and a metal oxide having a suitable average secondary particle size can be obtained. Further, it is preferable that the average primary particle size is 100 nm or less because each of the secondary particles of the metal oxide has an appropriate size and an electron extraction layer having a uniform film thickness is formed.

  The average primary particle size of the metal oxide can be measured with a dynamic light scattering particle size measuring device, a transmission electron microscope (TEM), or the like.

  Specific examples of metal oxides having an average primary particle size of 5 nm to 100 nm (sometimes referred to as metal oxide nanoparticles) include Nanozinc 60 (Honjo Chemical Co., Ltd.), FINEX-30, FINEX-50. (Manufactured by Sakai Chemical Industry Co., Ltd.).

  Further, the metal oxide particles may be surface-treated with a surface treatment agent to facilitate dispersion. The surface treatment agent is not particularly limited, but is a polysiloxane compound such as methylhydrogenpolysiloxane, polymethoxysilane, dimethylpolysiloxane, or dimethicone PEG-7 succinate and a salt thereof; a silane compound or the like (methyldimethoxysilane) , Dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, 3-aminopropyltriethoxysilane or 3-carboxypropyltrimethyltrimethoxysilane), organosilicon compounds, lauric acid, stearic acid, 2- (2-methoxy) Ethoxy) Acetic acid or carboxylic acid compound such as 6-hydroxyhexanoic acid; Organic phosphorus compound such as lauryl ether phosphoric acid or trioctylphosphine; Vine such as polyimine, polyester, polyamide, polyurethane, polyurea Over compounds. In addition, a surface treating agent may be used individually by 1 type, or may use 2 or more types together.

[5.2.1.2 Organic compounds]
Specific examples of the organic compound include bathocuproin (BCP), bathophenanthrene (Bphen), (8-hydroxyquinolinato) aluminum (Alq ₃ ), boron compound, oxadiazole compound, benzimidazole compound, and naphthalenetetracarboxylic acid. Examples include phosphine compounds having a double bond between an atom selected from Group 16 such as anhydride (NTCDA), perylenetetracarboxylic anhydride (PTCDA), or a phosphine oxide compound or phosphine sulfide compound, and a phosphorus atom. .

  Preferably, a phosphine having a double bond between an atom selected from the group 16 substituted with an aryl group such as a phosphine oxide compound substituted with an aryl group or a phosphine sulfide compound substituted with an aryl group and a phosphorus atom More preferably a triarylphosphine oxide compound, a triarylphosphine sulfide compound, an aromatic hydrocarbon compound having two or more diarylphosphine oxide units, an aromatic hydrocarbon compound having two or more diarylphosphine sulfide units, or An aromatic hydrocarbon compound having two or more diarylphosphine oxide units. The aryl group may be substituted with a fluorine atom or a fluorine atom-substituted alkyl group such as a perfluoroalkyl group. In addition to these materials, alkali metal or alkaline earth metal may be doped.

  The LUMO energy level of the material of the electron extraction layer 104 is not particularly limited, but is usually −5.0 eV or more, preferably −4.5 eV or more. On the other hand, it is usually −1.9 eV or less, preferably −2.0 eV or less. Although it is somewhat affected by the work function of the electrode used and the LUMO energy level of the n-type semiconductor, when the LUMO energy level of the material of the electron extraction layer 104 is within the range, electrons generated in the active layer are selectively In addition, since the loss of the open circuit voltage is eliminated, it leads to high photoelectric conversion efficiency.

  As a method for calculating the LUMO energy level of the material of the electron extraction layer 104, there is a cyclic voltammogram measurement method. For example, it can implement with reference to the method as described in well-known literature (International publication 2011/016430).

  The HOMO energy level of the material of the electron extraction layer 104 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 −5.5 eV or less, preferably −6.0 eV or less. When the HOMO energy level of the material of the electron extraction layer 104 is −5.5 eV or less, it is preferable in that the movement of holes can be prevented.

  When the material of the electron extraction layer 104 is an organic compound, the glass transition temperature (hereinafter also referred to as Tg) of this compound by the DSC method is not particularly limited but is not observed or 55 ° C. The above is preferable. That the glass transition temperature by DSC method is not observed 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 by DSC of 55 ° C. or higher, the glass transition temperature is preferably 65 ° C. or higher, more preferably 80 ° C. or higher, more preferably 110 ° C. or higher, and particularly preferably 120 ° C. or higher. Compounds 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. The material of the electron extraction layer 104 is preferably a material whose glass transition temperature by DSC method is not observed to be 30 ° C. or higher and lower than 55 ° C.

  The glass transition temperature in the present specification is a temperature at which local molecular motion is initiated by thermal energy in an amorphous solid of a compound, and is defined as a point at which specific heat changes. 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. What is necessary is just to measure a glass transition temperature by a well-known method, for example, DSC method is mentioned.

  The DSC method is a thermophysical property measurement method (differential scanning calorimetry method) defined in JIS K-0129 “General Rules for Thermal Analysis”. The glass transition temperature is a temperature at which molecular motion starts from a glass state, and can be measured by DSC as a temperature at which specific heat changes. 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, it can implement by the method as described in well-known literature (International Publication 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 the compound difficult 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 104 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 104 is 0.01 nm or more, it functions as a buffer material. When the film thickness of the electron extraction layer 104 is 40 nm or less, electrons are easily extracted, and photoelectric conversion is performed. Efficiency is improved.

  There is no limitation on the method for forming the electron extraction layer 104. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. Further, for example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as spin coating or inkjet. Moreover, you may use the film-forming process which concerns on this invention.

[5.2.2 Hole Extraction Layer (102)]
The material of the hole extraction layer 102 is not particularly limited as long as it can improve the efficiency of extracting holes from the organic active layer 103 to the anode 101. 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 Compounds, the above-mentioned p-type semiconductor compounds, and the like.

  Among them, a conductive polymer doped with sulfonic acid is preferable, and poly (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) (PEDOT: PSS) in which a polythiophene derivative is doped with polystyrene sulfonic acid is more preferable. A thin film of metal such as gold, indium, silver or palladium can also be used, and a metal oxide such as molybdenum trioxide is particularly preferable. Furthermore, 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 102 is not particularly limited, but is usually 2 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 hole extraction layer 102 is 2 nm or more, it functions as a buffer material. When the film thickness of the hole extraction layer 102 is 40 nm or less, holes are easily extracted, Conversion efficiency is improved.

  There is no limitation on the method of forming the hole extraction layer 102. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. Further, for example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as spin coating or inkjet. Moreover, you may use the film-forming process which concerns on this invention. When using a coating method, the coating solution may further contain a surfactant. By using the surfactant, generation of dents due to adhesion of fine bubbles, foreign matters, etc., uneven coating in the drying process, and the like are 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, 1 type may be used for surfactant and it may use 2 or more types together by arbitrary combinations and a ratio.

[5.3 Electrodes (101, 105)]
The electrodes (101, 105) according to the present invention have a function of collecting holes and electrons generated by light absorption. Any one of the pair of electrodes may be translucent, and both may be translucent. Translucency means that sunlight passes through 40% or more. In addition, it is preferable that the transparent electrode has a solar ray transmittance of 70% or more in order to allow light to reach the active layer through the transparent electrode. The light transmittance can be measured with a normal spectrophotometer.

[5.3.1 Anode]
The electrode 101 (anode) suitable for collecting holes is a conductive material generally having a work function higher than that of the cathode, and an electrode having a function of smoothly extracting holes generated in the organic active layer 103. It is. Examples of the material of the anode 101 include conductive oxides such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide, indium oxide, and zinc oxide; Examples thereof include metals such as gold, platinum, silver, chromium and cobalt, or alloys thereof.

  Since these substances have a high work function, they are preferable, and further, a conductive polymer material typified by PEDOT / PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid can be laminated. When laminating such a conductive polymer, the work function of the conductive polymer material is high, so that it is suitable for cathodes such as Al and Mg, even if it is not a material with a high work function as described above. Metals can also be widely used.

  A PEDOT / PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid, or a conductive polymer material doped with iodine or the like in polypyrrole or polyaniline can also be used as the anode material. When the anode 101 is a transparent electrode, it is preferable to use a conductive metal oxide having translucency such as ITO, zinc oxide or tin oxide, and ITO is particularly preferable.

  The film thickness of the anode 101 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 101 is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the anode 101 is 10 μm or less, light can be efficiently converted into electricity without decreasing the light transmittance. it can. When used for a transparent electrode, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance.

  The sheet resistance of the anode 101 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.

  A method for forming the anode 101 includes a vacuum film formation method such as vapor deposition or sputtering, or a method of forming a film by applying an ink containing nanoparticles or a precursor.

[5.3.2 Cathode]
The electrode 105 (cathode) suitable for collecting electrons is a conductive material generally having a work function higher than that of the anode, and is an electrode having a function of smoothly extracting electrons generated in the organic active layer 103. . In the example of FIG. 1, the cathode 105 is adjacent to the electron extraction layer 104.

  Examples of the material of the cathode 105 include metals such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium, and magnesium, and alloys thereof; lithium fluoride And inorganic salts such as cesium fluoride and metal oxides such as nickel oxide, aluminum oxide, lithium oxide, and cesium oxide. These materials are preferred because they have a low work function.

  Similarly to the anode 101, a material having a high work function suitable for the anode 101 can be used for the cathode 105 by using an n-type semiconductor such as titania having conductivity for the electron extraction layer 104. From the viewpoint of electrode protection, the anode 101 material is preferably a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium and an alloy using these metals.

  The film thickness of the cathode 105 is not particularly limited, but is usually 10 nm or more, preferably 20 nm or less, 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 used for a transparent electrode, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance. When the film thickness of the cathode 105 is 10 nm or more, sheet resistance is suppressed, and when the film thickness of the cathode 105 is 10 μm or less, light can be efficiently converted into electricity without a decrease in light transmittance. it can.

  The sheet resistance of the cathode 105 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 the method for forming the cathode 105 include a vacuum film formation method such as vapor deposition or sputtering, or a method of forming a film by applying an ink containing nanoparticles or a precursor.

  Further, two or more layers of the anode 101 or the cathode 105 may be stacked, and characteristics (electric characteristics, wetting characteristics, etc.) may be improved by surface treatment.

[5.3.3 Heat treatment after electrode lamination]
After laminating anode 101 and cathode 105, the obtained photoelectric conversion element is usually at a temperature range of 50 ° C. or higher, preferably 80 ° C. or higher, and usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower. In this case, it is preferable to perform heat treatment (this step may be referred to as a post-annealing treatment step). It is preferable to set the temperature of the annealing treatment step to 50 ° C. or higher because an effect of improving the adhesion between the electron extraction layer 104 and the electrode 101 and / or the electron extraction layer 104 and the organic active layer 103 can be obtained. It is preferable that the temperature of the annealing process be 300 ° C. or lower because the possibility that the organic compound in the active layer is thermally decomposed is reduced.

  In addition, about temperature operation, you may heat in steps within the said range. The heating time is usually 1 minute or longer, preferably 3 minutes or longer, and usually 3 hours or shorter, preferably 1 hour or shorter. The post annealing process is preferably terminated when the open circuit voltage, the short circuit current, and the fill factor, which are parameters of the solar cell performance, reach a constant value. Further, it is preferable that the annealing treatment be performed under normal pressure and in an inert gas atmosphere.

  By improving the adhesion between the electron extraction layer 104 and the electrode 101 and / or the electron extraction layer 104 and the organic active layer 103 by the post annealing process, the thermal stability and durability of the photoelectric conversion element are improved. The effect of promoting the self-organization of the organic active layer can be obtained. 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 put in a heating atmosphere such as an oven. Moreover, it may be a batch type or a continuous type.

[5.4 Substrate (106)]
The photoelectric conversion element 107 according to the present invention has a substrate 106 that is usually a support. That is, an electrode, an active layer, and a buffer layer are formed on the substrate. The material of the substrate (substrate material) is arbitrary as long as the effect is not significantly impaired.

  Preferable examples of the substrate material include inorganic materials such as quartz, glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluororesin Film, polyolefin such as vinyl chloride or polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene, epoxy resin or other organic material; paper such as paper or synthetic paper; stainless steel, titanium Alternatively, composite materials such as those obtained by coating or laminating a surface of a metal such as aluminum so as to provide insulation can be used.

  Examples of the glass include soda glass, blue plate glass, and alkali-free glass. As for the glass material, alkali-free glass is preferred because it is better that there are fewer ions eluted from the glass.

  There is no restriction | limiting in the shape of the board | substrate 106, For example, shapes, such as a board, a film, a sheet | seat, can be used. There is no limitation on the film thickness of the substrate 106. However, it is usually 5 μm or more, particularly 20 μm or more, and on the other hand, it is usually preferably 20 mm or less, particularly preferably 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 semiconductor device is insufficient is reduced. It is preferable that the film thickness of the substrate is 20 mm or less because the cost is suppressed and the weight is not increased. When the substrate is glass, the film thickness is usually 0.01 mm or more, preferably 0.1 mm or more, while it is usually 1 cm or less, preferably 0.5 cm or less. When the film thickness of the glass substrate is 0.01 mm or more, the mechanical strength increases and it is difficult to break, which is preferable. When the film thickness of the glass substrate is 0.5 cm or less, it is preferable because the weight does not increase.

[5.5 Manufacturing Method of Photoelectric Conversion Element]
The manufacturing method of a photoelectric conversion element is not specifically limited. By sequentially laminating each layer by the method described above for each layer, the photoelectric conversion element according to the present invention can be manufactured. For example, a method for manufacturing a photoelectric conversion element as an example includes a step of forming one electrode, a step of forming an organic active layer according to the present invention, and a step of forming the other electrode. In the case of manufacturing the photoelectric conversion element 107 illustrated in FIG. 1, the electrode 101, the hole extraction layer 102, the organic active layer 103, the electron extraction layer 104, and the electrode 105 may be sequentially stacked over the substrate 106. As described above, the organic active layer 103 is formed by a method including a film forming process according to the present invention. In order to prevent deterioration of the organic active layer 103, the organic active layer is subjected to sulfur oxidation until another layer (for example, the electron extraction layer 104) is formed on the organic active layer 103 after the organic active layer 103 is formed. It is preferable to maintain in an environment where the concentration of the product and the nitrogen oxide is not more than a predetermined concentration. This environment preferably satisfies the condition (1) or (2) described for the film forming process according to the present invention, and more preferably satisfies both the conditions (1) and (2). .

<6. Organic solar cell>
The photoelectric conversion element 107 according to this embodiment is preferably used as an organic solar battery, particularly an organic solar battery element of an organic thin film solar battery.

  FIG. 2 is a cross-sectional view schematically showing a configuration of an organic 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.

[6.1 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, the weather-resistant protective film 1 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the light 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, silicone 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 treatments, such as a corona treatment and / or a plasma treatment, for the weather-resistant protective film 1 in order to improve 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.

[6.2 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, a gas barrier film (3, 9), etc. Can be protected from ultraviolet rays and the power generation capacity can be kept high.

  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. Further, the ultraviolet cut film 2 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the light 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, the ultraviolet cut film 2 has a high softness | flexibility, its adhesiveness with an adjacent film is favorable, and what can cut water vapor | steam and oxygen is preferable.

  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.

  As the ultraviolet absorber, for example, salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ones can be used. 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 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.

[6.3 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.

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. For example, the water vapor transmission rate per unit area (1 m ² ) is usually 1 × 10. It is preferably ⁻¹ g / m ² / day or less, and the lower limit is not limited.

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. For example, the oxygen permeability per unit area (1 m ² ) is usually 1 ×. It is preferable that it is 10 < ^-1 > cc / m < ² > / day / atm or less, and there is no restriction | limiting in a lower limit.

  Further, the gas barrier film 3 is preferably one that transmits visible light from the viewpoint of not preventing the light absorption of the solar cell element 6. 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.

[6.4 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, the getter material film 4 is preferably one that 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, the 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 connected to the solar cell element 6 and the gas barrier film ( 3 and 9). In addition, when using a highly waterproof sheet such as a sheet obtained by bonding a fluororesin film on 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. .

[6.5 Sealant 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.

  In addition, the sealing material 5 is preferably one that 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.

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

[6.6 Solar cell element 6]
The solar cell element 6 is the same as the above-described organic photoelectric conversion element. 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 the clearance 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.

[6.7 Sealant 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.

[6.8 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.

[6.9 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.

[6.10 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.

[6.11 Dimensions, etc.]
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 the cost can be greatly reduced.

  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.

[6.12 Manufacturing method]
Although there is no restriction | limiting in the manufacturing method of the thin film solar cell 14 of this embodiment, For example, as a solar cell manufacturing method of the form of FIG. 2, after producing the laminated body shown by FIG. Is mentioned. Since the solar cell element of the present invention 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, the laminating method using a photo-curing adhesive having a proven record in organic EL device sealing, the hot melt laminate having a proven record in solar cells, and the thermal laminate are preferable. 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 reliably performed, and the sealing materials 5 and 7 from the end can be prevented from protruding or reduced in film thickness due to over-pressurization, 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.

[6.13 Applications]
There is no restriction | limiting in the use of the organic solar cell of this invention, especially the organic thin film solar cell 14 mentioned above, It can use for arbitrary uses. Examples of fields to which the thin film solar cell of the present invention is applied include solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railways, solar cells for ships, solar cells for airplanes, solar cells for spacecraft. Batteries, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like.

  The organic solar cell of the present invention, in particular, the organic thin film solar cell may be used as it is, or the organic solar cell may be installed on a substrate and used as an organic solar cell module. This organic solar cell module includes the organic photoelectric conversion element according to the present invention. For example, as schematically shown in FIG. 3, a solar cell module 13 including a thin film solar cell 14 on a base material 12 is prepared and used at a place of use. 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 solar cell element 6. 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 the Example of this invention is shown and this invention is demonstrated more concretely, this invention is not limited to a following example, unless it deviates from the summary.

(Measurement method of weight average molecular weight and number average molecular weight)
The weight average molecular weight and number average molecular weight in terms of polystyrene were determined by gel permeation chromatography (GPC).

Gel permeation chromatography (GPC) measurement was performed under the following conditions.
Columns: Shim-pack GPC-803 (manufactured by Shimadzu Corporation, inner diameter 8.0 mm, length 30 cm) and Shim-pack GPC-804 (manufactured by Shimadzu Corporation, inner diameter 8.0 mm, length 30 cm) (one each) Connected in series)
Pump: LC-10AT (manufactured by Shimadzu Corporation)
Oven: CTO-10A (manufactured by Shimadzu Corporation)
Detector: differential refractive index detector (manufactured by Shimadzu Corporation: RID-10A) and UV-vis detector (manufactured by Shimadzu Corporation: SPD-10A)
Sample: 5 μL of sample dissolved in tetrahydrofuran (THF)
Mobile phase: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min
Analysis: LC-Solution (manufactured by Shimadzu Corporation)

(Elemental analysis measurement method)
After wet decomposition of the sample, palladium (Pd) and tin (Sn) in the decomposition solution were analyzed with an ICP mass spectrometer to determine the amount. In addition, the sample is combusted with a sample combustion apparatus (QF-02 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.), the combustion gas is absorbed in an alkaline absorbent containing a reducing agent, bromine ions (Br ⁻ ) in the absorbent and Iodine ions (I ⁻ ) were analyzed with an ICP mass spectrometer to determine the amount.
Apparatus: ICP mass spectrometer (manufactured by Agilent Technologies, 7500ce type)
Analysis: Calibration curve method

(Concentration measurement method)
The sulfur oxide concentration was measured by an ion chromatography method. Specifically, the gas to be measured is collected for 2 hours by passing it through water at a rate of 1.5 L / min, and analyzed by an ion chromatograph analyzer DX500 type (manufactured by DIONEX). The sulfur oxide concentration in the gas was quantified. The detection limit by this method is 0.1 μg / m ³ .

The nitrogen oxide concentration was measured by an ion chromatography method. Specifically, the gas to be measured is collected for 2 hours by passing it through water at a rate of 1.5 L / min, and this is analyzed by using an ion chromatograph analyzer DX500 type (manufactured by DIONEX). The nitrogen oxide concentration in the gas was quantified. The detection limit by this method is 0.1 μg / m ³ .

  In Example 1 and Comparative Example 2, the relative humidity in the clean booth at the time of spin coating for forming an organic active layer is a temperature / humidity meter (testo 608-H2 manufactured by Testo), which is a kind of capacitance hygrometer. ). In Comparative Example 1, the oxygen concentration in the glove box during spin coating for forming the organic active layer was measured using an oximeter (MBRAUM, MB OX-SE-1), and the relative humidity was electrolysis. It measured using the type | formula moisture meter (the MBRAUM company make, MB MO-SE-1).

(Evaluation of photoelectric conversion element)
A 4 mm square metal mask is attached to the photoelectric conversion element, a solar simulator with an air mass (AM) of 1.5 G and an irradiance of 100 mW / cm ² is used as an irradiation light source, and an ITO electrode and a source meter (type 2400, manufactured by Keithley) The current-voltage characteristics with the silver electrode were measured. From this measurement result, open circuit voltage Voc (V), short circuit current density Jsc (mA / cm ² ), form factor FF, and photoelectric conversion efficiency PCE (%) were calculated.

Here, the open circuit voltage Voc is a voltage value when the current value = 0 (mA / cm ² ), and the short circuit current density Jsc is a current density when the voltage value = 0 (V). The form factor FF is a factor representing the internal resistance, and is represented by the following expression when the maximum output of the photoelectric conversion element is Pmax (W).
FF = Pmax / (Voc × Jsc)
Further, the photoelectric conversion efficiency PCE is given by the following equation when the incident energy is Pin.
PCE = Pmax / Pin = Voc × Jsc × FF / Pin × 100

<Synthesis Example 1: Synthesis of imidothiophene monomer>

  Thiophenedicarboxylic acid (Compound E11, 5.3 g, 30.7 mmol) and acetic anhydride (100 mL) were added to a 500 mL eggplant flask and heated at 140 ° C. for 6 hours. The solvent was removed by distillation under reduced pressure, and 1H, 3H-thieno [3,4-c] furan-1,3-dione (Compound E12, 3.5 g) was obtained by recrystallization using toluene. .

  Compound E12 (3.57 g, 0.023 mol) was dissolved in dehydrated N, N-dimethylformamide (35 mL) in a 100 mL eggplant flask under nitrogen. Next, n-octylamine (4.2 mL, 0.025 mol) was added while cooling in an ice bath, followed by heating at 140 ° C. for 2 hours. After allowing to cool, water was added and the precipitated skin color powder was collected by filtration. The obtained powder was washed with cold methanol to obtain 4-[[1-octylamino] carbonyl] -3-thiophenecarboxylic acid (Compound E13, 5.3 g).

  Compound E13 (5.27 g, 18.6 mmol) and thionyl chloride (18 mL) were added to a 100 mL eggplant flask and heated in a warm bath set at 72 ° C. for 3 hours. After allowing to cool, the reaction solution was dropped into a 1N aqueous sodium hydroxide solution, and the precipitated brown powder was collected by filtration. The obtained powder was washed with cold methanol and dried to give 5-octyl-4H-thieno [3,4-c] pyrrole-4,6 (5H) -dione (compound E14, 4.55 g, yield). 91%).

  Compound E14 (2.65 g, 10 mmol) was dissolved in trifluoroacetic acid (50 mL) and concentrated sulfuric acid (15 mL) in a 200 mL eggplant flask under nitrogen. While cooling in an ice bath, N-bromosuccinimide (NBS, 5.33 g, 30 mmol) was further added and stirred until dissolved. Thereafter, the ice bath was removed, the liquid temperature was raised to room temperature, and the mixture was further stirred for 20 hours. After the reaction solution was mixed with ice water, the product was extracted with chloroform, and the solvent was distilled off under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (developing solvent: hexane / chloroform = 2/1 → 1/1). By suspending and washing the purified product with hexane, 1,3-dibromo-5-octyl-4H-thieno [3,4-c] pyrrole-4,6- (5H) -dione (imidothiophene monomer, Compound E1, 2.58 g, yield 61%) was obtained.

<Synthesis Example 2: Synthesis of dithienosilole monomer>

  4,4′-Dioctyl-5,5-dibromo-dithieno [3,2-b: 2 ′, 3′-d] silole (compound E21, 0.9 g) was added to a 50 mL multi-necked flask, and a vacuum pump and dryer Was used to sufficiently replace the inside of the flask with nitrogen. Thereafter, dehydrated tetrahydrofuran (30 mL) was added, and the reaction solution was cooled in a dry ice-acetone bath. Then, n-butyllithium (1.6 M hexane solution, 2.44 mL, 3.9 mmol) was added and stirred for 15 minutes. Thereafter, trimethyltin chloride (1.0 M tetrahydrofuran solution, 4.68 mL) was added, the temperature of the reaction solution was raised to room temperature, and the mixture was further stirred for 2 hours. Thereafter, water was added to the reaction solution, and the product was extracted with hexane, and then the organic layer was dried using sodium sulfate. (4,4′-Dioctyl-5,5-bis (trimethyltin) -dithieno [3,2-b: 2 ′, 3′-d] silole (dithienosilol) by removing the solvent by distillation under reduced pressure. Monomer, Compound E2, 600 mg) was obtained as a green oil.

<Synthesis Example 3: Synthesis of Copolymer A1>

  In a 50 mL eggplant flask under nitrogen, the imidothiophene monomer obtained in Synthesis Example 1 (Compound E1, 245.23 mg, 0.61 mmol) and the dithienosilole monomer obtained in Synthesis Example 2 (Compound E2, 453.4 mg, 0 .58 mmol), tetrakis (triphenylphosphine) palladium (zero valent) (20.1 mg, 0.02 mmol), copper (II) oxide (47.5 mg, 0.61 mmol), toluene (9.24 mL) and N, N -Dimethylformamide (2.32 mL) was added, and it stirred at 90 degreeC for 1 hour, Then, it stirred at 100 degreeC for 9 hours. Then, as a terminal treatment, bromobenzene (0.5 mL) was added and stirred with heating for 8 hours. Trimethyl (phenyl) tin (0.5 mL) was further added and stirred with heating for 8 hours, and then the reaction solution was diluted 5 times with toluene. After dilution, it was added dropwise to methanol (400 mL). The precipitated copolymer was collected by filtration and purified by silica gel column chromatography to obtain copolymer A1. Specifically, using a JAL908-C60 apparatus (manufactured by Nihon Analysis Kogyo Co., Ltd.) in which JAIGEL-3H (40φ) and 2H (40φ) are attached in series, chloroform is used as a developing solution, and the flow rate is 14 mL / min. The solution was filtered and filled with a chloroform solution (30 mL) of the copolymer (350 to 400 mg).

When the weight average molecular weight and the number average molecular weight of the fractionated copolymer A1 were measured as described above, they were 8.6 × 10 ⁴ and 4.7 × 10 ⁴ , respectively. The molecular weight distribution (PDI) was 1.8. When the elemental analysis of the copolymer A was performed as described above, it was found that Br: 47 ppm, Pd: 19 ppm, and Sn: 870 ppm.

<Example 1>
(Preparation of organic active layer coating solution S1)
a copolymer A1 obtained in p-type semiconductor compound in a Synthesis Example 3, an n-type semiconductor material PC61BM ([6,6] - phenyl _{C 61} butyric acid methyl ester, manufactured by Frontier Carbon Corporation, E100H) a weight ratio of The mixture was mixed at 1: 2 and dissolved in a mixed solvent of orthoxylene and tetralin (volume ratio 4: 1) in a nitrogen atmosphere so that the mixture had a concentration of 1.8% by weight. This solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 1 hour. The solution after stirring and mixing was filtered through a polytetrafluoroethylene (PTFE) filter having a pore size of 1.0 μm to obtain an organic active layer coating solution S1.

(Organic active layer deposition environment)
The organic active layer was formed in the apparatus (clean booth) shown in FIG. As the housing 21, a simple clean booth (manufactured by ASONE, AIW type) is used, and a blower 23 (with a fan filter unit (manufactured by ASONE, PS01-A), a HEPA filter (manufactured by ASONE)) on the upper surface of the housing 21 and Air purifying means 22 (chemical filter (product name CG-AX, manufactured by Nichias)) was installed. Air is supplied to the housing 21 by the blower 23 through the HEPA filter and the chemical filter. The amount of air blown and the speed of air supplied to the housing 21 via the air purification means 22 were about 3 m ³ / min and about 2.0 m / s, respectively. In addition, a spin coater (manufactured by Mikasa, product name 1H-D7) was installed in the housing 21.

  In order to reduce the sulfur oxide concentration or nitrogen oxide concentration in the clean booth, the organic active layer was formed after the blower 23 was driven for 30 minutes or more.

(Preparation of photoelectric conversion element)
The glass substrate on which the indium tin oxide (ITO) transparent conductive film was patterned was ultrasonically cleaned with acetone, further ultrasonically cleaned with isopropyl alcohol, and dried by nitrogen blowing. Next, ultraviolet ozone cleaning was performed on the substrate.

  Zinc acetate dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in a mixed solvent of methoxyethanol and ethanolamine (weight ratio 100: 3) to a concentration of 9.8% by weight. About 0.4 mL of the obtained dispersion was dropped onto the washed substrate, and the dispersion was applied onto the substrate by spin coating under the conditions of 4000 rpm and 30 seconds. The substrate after coating was subjected to ultraviolet ozone cleaning for 10 minutes using an ultraviolet ozone cleaning apparatus (manufactured by Philgen), then heated in the air for 10 minutes on a 150 ° C. hot plate, and further heated to 200 ° C. Heated in air for 10 minutes on plate. Thus, an electron extraction layer containing zinc oxide was formed on the substrate. The film thickness of the formed electron extraction layer was about 30 nm.

  The substrate on which the electron extraction layer was formed was heat-treated at 200 ° C. for 3 minutes on a hot plate in a nitrogen atmosphere glove box (Labmaster series manufactured by MBRAUM). After the substrate is cooled, the substrate is placed in the clean booth, and the organic active layer coating solution S1 (about 0.1 mL) prepared as described above is spin-coated at a speed of 300 rpm, so that the thickness is about 100 nm. An organic active layer was formed. The sulfur oxide concentration and nitrogen oxide concentration in the clean booth were below the detection limit, and the relative humidity was 50.2%. Since a special oxygen removing device is not used, the oxygen concentration in the clean booth is considered to be the same as that in the normal atmosphere (that is, 18 to 22% by volume).

  Thereafter, molybdenum trioxide was formed as a hole extraction layer on the organic active layer by resistance heating vacuum deposition so as to have a thickness of 3 nm. Further, silver was formed as an electrode on the hole extraction layer by resistance heating vacuum deposition so as to have a film thickness of 100 nm. Thus, a 5 mm square photoelectric conversion element was produced. The photoelectric conversion element thus manufactured was measured for current-voltage characteristics as described above. The measurement results are shown in Table 1.

<Comparative Example 1>
Using a spin coater (MS-A100, manufactured by Mikasa Co., Ltd.) as a spin coat for forming an organic active layer, a dry nitrogen atmosphere in which the sulfur oxide concentration and nitrogen oxide concentration are below the detection limit (oxygen concentration is 5 ppm) Hereinafter, a photoelectric conversion element was produced in the same manner as in Example 1 except that it was performed in a glove box (Labmaster series manufactured by MBRAUM) under a relative humidity of 0.1%. The photoelectric conversion element thus manufactured was measured for current-voltage characteristics as described above. The measurement results are shown in Table 1.

<Comparative example 2>
Spin coating for forming the organic active layer, the atmosphere of sulfur oxide concentration and nitrogen oxide concentration, respectively 1.9μg / ^{m 3} and 2.6μg / ^{m 3} (relative humidity 48.1%) lower A photoelectric conversion element was produced in the same manner as in Example 1 except that the above was performed. Since a special oxygen removing device is not used, the oxygen concentration in the clean booth is considered to be the same as that in the normal atmosphere (that is, 18 to 22% by volume). The photoelectric conversion element thus manufactured was measured for current-voltage characteristics as described above. The measurement results are shown in Table 1.

The photoelectric conversion element according to Example 1 showed higher photoelectric conversion efficiency than the photoelectric conversion element according to Comparative Example 1. Thus, even when the organic active layer is formed in an air atmosphere from which oxygen and moisture are not removed, a dry nitrogen atmosphere can be obtained by reducing the sulfur oxide concentration and nitrogen oxide concentration in the atmosphere. It was found that a photoelectric conversion element having an efficiency equal to or higher than that in the case where the organic active layer is formed under the film can be obtained. On the other hand, as in Comparative Example 2, the sulfur oxide concentration in the atmosphere during the formation of the organic active layer exceeded 1.2 ug / m ^3, the nitrogen oxide concentration is greater than 2.5 [mu] g / m ³ In this case, the conversion efficiency of the obtained photoelectric conversion element was reduced as compared with Example 1 in which the sulfur oxide concentration and the nitrogen oxide concentration were reduced.

  Thus, by reducing the sulfur oxide concentration or nitrogen oxide concentration in the atmosphere when forming the organic active layer, photoelectric conversion having high photoelectric conversion efficiency without reducing oxygen and moisture in the atmosphere It was found that the device can be manufactured.

DESCRIPTION OF SYMBOLS 1 Weather-resistant 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 module 14 Thin film solar cell 101 Anode 102 Hole extraction Layer 103 Active layer 104 Electron extraction layer 105 Cathode 106 Substrate 107 Photoelectric conversion element

Claims (8)

A method for producing an organic photoelectric conversion device having at least a pair of electrodes and an organic active layer between the electrodes,
Including a film forming step of forming the organic active layer by a wet film forming method,
The method for producing an organic photoelectric conversion element, wherein the film forming step is performed in an environment where an oxygen concentration is 18% by volume or more and 22% by volume or less and satisfies the following (1) or (2).
(1) The sulfur oxide concentration is 1.2 μg / m ³ or less.
(2) Nitrogen oxide concentration is 2.5 μg / m ³ or less.   The method for producing an organic photoelectric conversion element according to claim 1, wherein the film forming step is performed in an environment satisfying the conditions (1) and (2).   The method for producing an organic photoelectric conversion element according to claim 1, wherein the material of the organic active layer contains at least one type of polymer p-type semiconductor compound.   An organic photoelectric conversion element manufactured by the method for manufacturing an organic photoelectric conversion element according to any one of claims 1 to 3.   It is an organic solar cell, The organic photoelectric conversion element of Claim 4 characterized by the above-mentioned.   An organic solar cell module comprising the organic photoelectric conversion element according to claim 4.   A supply device for supplying outside air to a film forming apparatus for forming an organic active layer of an organic photoelectric conversion element by a wet film forming method, and sulfur oxide or nitrogen oxidation in the outside air supplied to the film forming apparatus A supply device comprising a removing means for removing an object. A supply device according to claim 7;
A housing for receiving outside air supplied from the supply device;
A film forming means disposed in the housing and forming an organic active layer of the organic photoelectric conversion element by a wet film forming method;
A film forming apparatus comprising:

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