JP2015099810A - Method of manufacturing organic photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an organic photoelectric conversion element having photoelectric conversion efficiency.SOLUTION: A method of manufacturing an organic photoelectric conversion element is provided which includes the steps of: forming a cathode; forming an oxide layer containing a zinc oxide doped with gallium on the cathode; and forming an active layer on the oxide layer. Moreover, the method of manufacturing the organic photoelectric conversion element is provided which forms the oxide layer by applying the coating liquid containing the zinc oxide doped with gallium on the cathode to form the film.

Description

  The present invention relates to a method for producing an organic photoelectric conversion element.

  An organic photoelectric conversion element used for an organic solar cell or an optical sensor is composed of a pair of electrodes (anode and cathode) and an active layer provided between the electrodes. It is produced by laminating in order.

  In order to improve the photoelectric conversion efficiency, the organic photoelectric conversion element may be provided with an additional layer such as an electron transport layer or a hole transport layer in addition to the active layer. As a method for producing an organic photoelectric conversion element provided with an electron transport layer, a production method having a step of forming a layer made of zinc oxide on an ITO electrode as a cathode is known (for example, see Non-Patent Document 1). .

Advanced Energy Materials Vol. 3 (2013) Pages 301-307

  In the method described in Non-Patent Document 1 in which a layer made of zinc oxide is formed as an electron transport layer, there is a problem that the photoelectric conversion efficiency is not necessarily high. Therefore, the objective of this invention is providing the method of manufacturing an organic photoelectric conversion element with high photoelectric conversion efficiency.

The present invention includes a step of forming a cathode;
Forming an oxide layer comprising zinc oxide doped with gallium on the cathode;
Forming an active layer on the oxide layer.

  The present invention also relates to a method for producing an organic photoelectric conversion element, wherein the oxide layer is formed by coating the gallium-doped zinc oxide on a cathode.

  Moreover, this invention relates to the manufacturing method of the organic photoelectric conversion element whose zinc oxide doped with the said gallium is a particulate form.

  The present invention also relates to a method for producing an organic photoelectric conversion element in which an active layer contains fullerenes and / or derivatives of fullerenes and a conjugated polymer compound.

  According to the present invention, an organic photoelectric conversion element having high photoelectric conversion efficiency can be manufactured.

  Hereinafter, the present invention will be described in detail.

<1> Configuration of Organic Photoelectric Conversion Element The organic photoelectric conversion element produced by the production method of the present invention has a cathode, an oxide layer doped with gallium, an active layer, and an anode laminated in this order on a support substrate. It is the organic photoelectric conversion element of the structure comprised.

  At least one of the anode and the cathode is constituted by a transparent or translucent electrode. Light incident from a transparent or translucent electrode is absorbed in the active layer by an electron-accepting compound and / or an electron-donating compound described later, thereby generating excitons in which electrons and holes are combined. . When the exciton moves in the active layer and reaches the heterojunction interface where the electron accepting compound and the electron donating compound are adjacent to each other, the difference between the HOMO energy and the LUMO energy at the interface causes the electrons and holes to be separated. Charges (electrons and holes) are generated that can separate and move independently. The generated electric charges are taken out as electric energy (current) by moving to the electrodes.

(Support substrate)
The organic photoelectric conversion element of the present invention is usually formed on a support substrate. As the support substrate, one that does not change chemically when an organic photoelectric conversion element is produced is suitably used. Examples of the support substrate include a glass substrate, a plastic substrate, a polymer film, and a silicon plate. In the case of an organic photoelectric conversion element in which light is taken from a transparent or translucent cathode, a substrate having high light transmittance is preferably used as the support substrate. Further, when an organic photoelectric conversion element is produced on an opaque substrate, light cannot be taken in from the cathode side, so that the anode is composed of a transparent or translucent electrode. By using such an electrode, even if an opaque support substrate is used, light can be taken in from the anode on the side opposite to the cathode provided on the support substrate side.

(Active layer)
The active layer can take the form of a single layer or a stack of a plurality of layers. The active layer having a single layer structure is composed of a layer containing an electron accepting compound and an electron donating compound.

  In addition, the active layer having a configuration in which a plurality of layers are stacked includes, for example, a stacked body in which a first active layer containing an electron-accepting compound and a second active layer containing an electron-donating compound are stacked. The In this case, the first active layer is disposed closer to the cathode than the second active layer.

  Moreover, the organic photoelectric conversion element may have a configuration in which a plurality of active layers are stacked via an intermediate layer. In such a case, a multi-junction element (tandem element) is formed. In this case, each active layer may be a single layer type containing an electron-accepting compound and an electron-donating compound, or a first active layer containing an electron-accepting compound and an electron-donating compound. It may be a laminated type constituted by a laminated body in which a second active layer contained is laminated.

  The intermediate layer may take the form of a single layer or a stack of a plurality of layers. The intermediate layer is constituted by a so-called charge injection layer or charge transport layer. For the intermediate layer, for example, a functional layer containing an electron transporting material described later can be used.

  The active layer is preferably formed by a coating method. Moreover, it is preferable that an active layer contains a high molecular compound, and may contain the high molecular compound individually by 1 type, or may contain it in combination of 2 or more types. Moreover, in order to improve the charge transport property of the active layer, an electron donating compound and / or an electron accepting compound may be mixed in the active layer.

  The electron-accepting compound used for the organic photoelectric conversion element is composed of a compound having a HOMO energy higher than that of the electron-donating compound and a LUMO energy higher than that of the electron-donating compound.

  The electron donating compound may be a low molecular compound or a high molecular compound. Examples of the low molecular electron-donating compound include phthalocyanine, metal phthalocyanine, porphyrin, metal porphyrin, oligothiophene, tetracene, pentacene, and rubrene.

  Polymeric electron donating compounds include polyvinylcarbazole and derivatives thereof, polysilane and derivatives thereof, polysiloxane derivatives having aromatic amines in the side chain or main chain, polyaniline and derivatives thereof, polythiophene and derivatives thereof, polypyrrole and derivatives thereof , Polyphenylene vinylene and derivatives thereof, polythienylene vinylene and derivatives thereof, polyfluorene and derivatives thereof, and the like.

The electron-accepting compound may be a low molecular compound or a high molecular compound. Low molecular electron accepting compounds include oxadiazole derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives, fluorenone derivatives , diphenyldicyanoethylene and derivatives thereof, diphenoquinone derivatives, 8-hydroxyquinoline and metal complexes of derivatives thereof, polyquinoline and derivatives thereof, polyquinoxaline and derivatives thereof, polyfluorene and derivatives thereof, fullerenes and derivatives thereof such as C _60, bathocuproine And the like, and the like. Polymeric electron-accepting compounds include polyvinylcarbazole and derivatives thereof, polysilane and derivatives thereof, polysiloxane derivatives having aromatic amines in the side chain or main chain, polyaniline and derivatives thereof, polythiophene and derivatives thereof, polypyrrole and derivatives thereof , Polyphenylene vinylene and derivatives thereof, polythienylene vinylene and derivatives thereof, polyfluorene and derivatives thereof, and the like. Among these, fullerenes and derivatives thereof are particularly preferable.

Examples of fullerenes include C ₆₀ , C ₇₀ and carbon nanotubes. Specific examples of the C ₆₀ fullerene derivative include the following.

  In the structure in which the active layer contains an electron-accepting compound composed of fullerenes and / or fullerene derivatives and an electron-donating compound, the proportion of fullerenes and fullerene derivatives is 100 parts by weight of the electron-donating compound. The amount is preferably 10 to 1000 parts by weight, and more preferably 50 to 500 parts by weight. In addition, the organic photoelectric conversion element preferably includes the active layer having the above-described single layer structure, and from the viewpoint of including many heterojunction interfaces, an electron-accepting compound composed of fullerenes and / or derivatives of fullerenes, It is more preferable to provide an active layer having a single layer structure containing an electron donating compound.

  In particular, the active layer preferably contains a conjugated polymer compound and fullerenes and / or derivatives of fullerenes. Examples of the conjugated polymer compound used in the active layer include polythiophene and derivatives thereof, polyphenylene vinylene and derivatives thereof, polyfluorene and derivatives thereof, and the like.

  The thickness of the active layer is usually 1 nm to 100 μm, preferably 2 nm to 1000 nm, more preferably 5 nm to 500 nm, and further preferably 20 nm to 200 nm.

(Oxide layer)
The organic photoelectric conversion element of the present invention includes an oxide layer containing zinc oxide doped with gallium. This oxide layer is provided between the active layer and the cathode.

  Moreover, the doping concentration with respect to the zinc oxide of gallium is 0.1 mol%-50 mol% normally, 0.5 mol%-30 mol% are preferable, and 1 mol%-20 mol% are more preferable.

  By providing an oxide layer containing zinc oxide doped with gallium between the cathode and the active layer, the electron injection efficiency from the active layer to the cathode can be increased. Note that the oxide layer is preferably provided in contact with the active layer, and more preferably provided in contact with the cathode. By providing such an oxide layer, an organic photoelectric conversion element with high reliability and high photoelectric conversion efficiency can be realized.

  The oxide layer containing zinc oxide doped with gallium functions as a so-called electron transport layer and / or electron injection layer. By providing such an oxide layer, the efficiency of electron injection into the cathode can be increased, the injection of holes from the active layer can be prevented, the electron transport capability can be increased, and the active layer can be prevented from deteriorating. can do.

(electrode)
The organic photoelectric conversion element manufactured by the manufacturing method of the present invention has a pair of electrodes. One electrode of the pair of electrodes is an anode, and the other electrode is a cathode. At least one of the pair of electrodes is transparent or translucent. Examples of the material for the transparent or translucent electrode include a conductive metal oxide film and a translucent metal thin film. Specifically, indium oxide, zinc oxide, tin oxide, indium tin oxide (abbreviated as ITO), indium zinc oxide (abbreviated as IZO), gold, platinum, silver, and copper can be given. ITO, IZO and tin oxide are preferred. Moreover, you may use organic transparent conductive films, such as polyaniline and its derivative (s), polythiophene, and its derivative (s) as an electrode.

  The transparent or translucent electrode is preferably a cathode, and the cathode is indium oxide, zinc oxide, tin oxide, indium tin oxide (Indium Tin Oxide: abbreviation ITO), indium zinc oxide (Indium Zinc Oxide: abbreviation). IZO) and the like, and preferably formed of a conductive metal oxide, more preferably ITO, IZO, or tin oxide.

  One electrode of the pair of electrodes may be opaque. As the opaque electrode, for example, a metal thin film having a thickness that does not transmit light can be used. Examples of opaque electrode materials include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, Examples include metals such as gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, and tin, and alloys of two or more thereof, graphite, or graphite intercalation compounds.

  Further, the organic photoelectric conversion element is not limited to the element configuration described above, and an additional layer may be further provided between the anode and the cathode. Examples of the additional layer include a hole transport layer that transports holes, an electron transport layer that transports electrons, and a buffer layer. For example, the hole transport layer is provided between the anode and the active layer, the electron transport layer is provided between the active layer and the oxide layer, and the buffer layer is provided, for example, between the cathode and the oxide layer. By providing the buffer layer, planarization of the surface and charge injection can be promoted.

  As the material used for the hole transport layer or the electron transport layer as the additional layer, the above-described electron donating compound and electron accepting compound can be used, respectively. As a material used for the buffer layer as an additional layer, an alkali metal such as lithium fluoride, a halide of an alkaline earth metal, an oxide, or the like can be used. The charge transport layer can also be formed using fine particles of an inorganic semiconductor such as titanium oxide. For example, an electron transport layer can be formed by forming a titania solution on a base layer on which an electron transport layer is formed by a coating method and further drying.

<2> Manufacturing Method of Organic Photoelectric Conversion Device The manufacturing method of the organic photoelectric conversion device of the present invention includes a step of forming a cathode and a step of forming an oxide layer containing zinc oxide doped with gallium on the cathode. And a step of forming an active layer on the oxide layer. Each of these steps is performed in the order of description. The form in which the predetermined layer is formed on the predetermined layer includes a form in which these layers are in contact with each other and a form in which another predetermined layer is interposed between these layers.

<Cathode formation process>
The cathode is formed by depositing the above-described cathode material on the above-described supporting substrate by vacuum deposition, sputtering, ion plating, plating, or the like. Alternatively, the cathode may be formed by a coating method using a coating liquid containing an organic material such as polyaniline and derivatives thereof, polythiophene and derivatives thereof, metal ink, metal paste, a molten low melting point metal, or the like.

<Oxide layer forming step>
In this step, an oxide layer is formed on the cathode. That is, after the cathode is formed and before the active layer is formed, an oxide layer containing zinc oxide doped with gallium is formed. The oxide layer is preferably formed by a coating method, for example, by coating a coating liquid containing the above-described zinc oxide doped with gallium and a solvent on the surface of the layer on which the oxide layer is provided. It is preferable to form. In the present invention, the coating solution also includes dispersions such as emulsions (emulsions) and suspensions (suspensions).

  In forming the oxide layer, it is preferable to form a coating solution containing zinc oxide doped with particulate gallium to form the oxide layer. As such an electron transport material, it is more preferable to form an oxide layer using so-called gallium-doped zinc oxide nanoparticles. The average particle diameter corresponding to a sphere of zinc oxide doped with particulate gallium is preferably 1 nm to 1000 nm, and more preferably 10 nm to 100 nm. The average particle diameter is measured by a laser light scattering method or an X-ray diffraction method.

  When the oxide layer is provided in contact with the cathode, the oxide layer is formed by applying the coating liquid onto the surface of the cathode. In forming the oxide layer, it is preferable to use a coating solution that causes little damage to the layer to which the coating solution is applied (such as the cathode). Specifically, the layer to which the coating solution is applied (such as the cathode). It is preferable to use a coating solution that hardly dissolves.

  The coating solution used for coating and forming the oxide layer includes a solvent and zinc oxide doped with the above-described metal. Examples of the solvent for the coating solution include water, alcohol, and ketone. Specific examples of alcohol include methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butoxyethanol, methoxybutanol, and the like. Specific examples of these include acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, cyclohexanone, and a mixture of two or more thereof. Moreover, the coating liquid used for this invention may contain 2 or more types of solvent, and may contain 2 or more types of solvent illustrated above.

<Active layer forming step>
The method for forming the active layer is not particularly limited, but it is preferably formed by a coating method from the viewpoint of simplifying the production process. The active layer can be formed, for example, by a coating method using a coating solution containing the constituent material of the active layer and a solvent, and includes, for example, a conjugated polymer compound and fullerenes and / or fullerene derivatives and a solvent. It can be formed by a coating method using a coating solution.

Examples of the solvent include hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decalin, bicyclohexyl, n-butylbenzene, s-butylbezen, and t-butylbenzene, carbon tetrachloride, chloroform, dichloromethane, dichloroethane, and chlorobutane. Halogenated saturated hydrocarbon solvents such as bromobutane, chloropentane, bromopentane, chlorohexane, bromohexane, chlorocyclohexane and bromocyclohexane, halogenated unsaturated hydrocarbon solvents such as chlorobenzene, dichlorobenzene and trichlorobenzene, tetrahydrofuran, And ether solvents such as tetrahydropyran.
Moreover, the coating liquid used for this invention may contain 2 or more types of solvent, and may contain 2 or more types of solvent illustrated above.

  As a method of applying a coating solution containing the constituent material of the active layer, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, Examples of the spray coating method, screen printing method, flexographic printing method, offset printing method, ink jet printing method, dispenser printing method, nozzle coating method, capillary coating method, and the like include spin coating method and flexographic method. A printing method, an inkjet printing method, and a dispenser printing method are preferable.

<Anode formation process>
The anode is formed on the surface of an oxide layer or an active layer by a coating method or a vacuum film forming method.

The organic photoelectric conversion element of the present invention can be operated as an organic thin-film solar cell by irradiating light such as sunlight to a transparent or translucent electrode to generate photovoltaic power between the electrodes.
Moreover, it can also be used as an organic thin film solar cell module by integrating a plurality of organic thin film solar cells.

  In addition, the organic photoelectric conversion element of the present invention can be operated as an organic photosensor by irradiating light to a transparent or translucent electrode in a state where a voltage is applied between the electrodes, so that a photocurrent flows. It can also be used as an organic image sensor by integrating a plurality of organic photosensors.

  Examples will be shown below for illustrating the present invention in more detail, but the present invention is not limited to these examples.

  In the following Examples, the number average molecular weight in terms of polystyrene was determined using GPC Laboratories GPC (PL-GPC2000) as the molecular weight of the polymer. The polymer was dissolved in o-dichlorobenzene so that the concentration of the polymer was about 1% by weight. As the mobile phase of GPC, o-dichlorobenzene was used and allowed to flow at a measurement temperature of 140 ° C. at a flow rate of 1 mL / min. As the column, three PLGEL 10 μm MIXED-B (manufactured by PL Laboratory) were connected in series.

内部の気体をアルゴン置換した２Ｌ四つ口フラスコに、上記化合物Ａ（7.928g、16.72mmol）、上記化合物Ｂ（13.00g、17.60mmol）、メチルトリオクチルアンモニウムクロライド（商品名：aliquat336、Aldrich製、CH₃N[(CH₂)₇CH₃]₃Cl、density 0.884g/ml,25℃、trademark of Henkel Corporation）（4.979g）、およびトルエン405mlを入れ、撹拌しながら系内を30分間アルゴンバブリングした。ジクロロビス（トリフェニルホスフィン）パラジウム（ＩＩ）（0.02g）を加え、105℃に昇温、撹拌しながら2mol／Lの炭酸ナトリウム水溶液42.2mlを滴下した。滴下終了後5時間反応させ、フェニルボロン酸（2.6g）とトルエン1.8mlを加えて105℃で16時間撹拌した。トルエン700mlおよび7.5％ジエチルジチオカルバミン酸ナトリウム三水和物水溶液200mlを加えて85℃で3時間撹拌した。水層を除去後、60℃のイオン交換水300mlで2回、60℃の3％酢酸300mlで1回、さらに60℃のイオン交換水300mlで3回洗浄した。有機層をセライト、アルミナ、シリカを充填したカラムに通し、熱トルエン800mlでカラムを洗浄した。溶液を700mlまで濃縮した後、2Lのメタノールに注加、再沈殿させた。重合体をろ過して回収し、500mlのメタノール、アセトン、メタノールで洗浄した。50℃で一晩真空乾燥することにより、下記式：

で表される繰返し単位を有するペンタチエニル−フルオレンコポリマー（以下、「重合体１」という）を１２．２１ｇ得た。重合体１のポリスチレン換算の数平均分子量は５．４×１０⁴、重量平均分子量は１．１×１０⁵であった。 Synthesis example 1
(Synthesis of polymer 1)

Into a 2 L four-necked flask in which the internal gas was purged with argon, the above compound A (7.928 g, 16.72 mmol), the above compound B (13.00 g, 17.60 mmol), methyltrioctyl ammonium chloride (trade name: aliquat336, manufactured by Aldrich, CH ₃ N [(CH ₂ ) ₇ CH ₃ ] ₃ Cl, density 0.884 g / ml, 25 ° C, trademark of Henkel Corporation) (4.979 g), and 405 ml of toluene are added, and argon is bubbled through the system for 30 minutes with stirring. did. Dichlorobis (triphenylphosphine) palladium (II) (0.02 g) was added, and 42.2 ml of a 2 mol / L aqueous sodium carbonate solution was added dropwise while stirring at 105 ° C. with stirring. After completion of the dropwise addition, the mixture was reacted for 5 hours, phenylboronic acid (2.6 g) and 1.8 ml of toluene were added, and the mixture was stirred at 105 ° C. for 16 hours. Toluene 700 ml and 7.5% sodium diethyldithiocarbamate trihydrate 200 ml were added and stirred at 85 ° C. for 3 hours. After removing the aqueous layer, washing was performed twice with 300 ml of ion exchange water at 60 ° C., once with 300 ml of 3% acetic acid at 60 ° C., and further three times with 300 ml of ion exchange water at 60 ° C. The organic layer was passed through a column filled with celite, alumina, and silica, and the column was washed with 800 ml of hot toluene. The solution was concentrated to 700 ml, poured into 2 L of methanol, and reprecipitated. The polymer was recovered by filtration and washed with 500 ml of methanol, acetone, and methanol. By vacuum drying overnight at 50 ° C., the following formula:

12.21 g of a pentathienyl-fluorene copolymer (hereinafter referred to as “polymer 1”) having a repeating unit represented by the formula: The polystyrene equivalent number average molecular weight of the polymer 1 was 5.4 × 10 ⁴ , and the weight average molecular weight was 1.1 × 10 ⁵ .

２００ｍｌのセパラブルフラスコに、メチルトリオクチルアンモニウムクロライド（商品名：aliquat336（登録商標）、Aldrich製、CH₃N[(CH₂)₇CH₃]₃Cl、density ０．８８４ｇ／ｍｌ、２５℃）を０．６５ｇ、化合物（Ｃ）を１．５７７９ｇ、化合物（Ｅ）を１．１４５４ｇ入れ、フラスコ内の気体を窒素で置換した。フラスコに、アルゴンバブリングしたトルエンを３５ｍｌ加え、撹拌溶解後、さらに４０分アルゴンバブリングした。フラスコを加熱するバスの温度を８５℃まで昇温後、反応液に、酢酸パラジウム１．６ｍｇ、トリスｏ−メトキシフェニルフォスフィンを６．７ｍｇ加え、つづいてバスの温度を１０５℃まで昇温しながら、１７．５重量％の炭酸ナトリウム水溶液９．５ｍｌを６分かけて滴下した。滴下後、バスの温度を１０５℃に保った状態で１．７時間攪拌し、その後、反応液を室温まで冷却した。 Synthesis example 2
(Synthesis of polymer 2)

In a 200 ml separable flask, methyl trioctyl ammonium chloride (trade name: aliquat336 (registered trademark), manufactured by Aldrich, CH ₃ N [(CH ₂ ) ₇ CH ₃ ] ₃ Cl, density 0.884 g / ml, 25 ° C.) 0.65 g, compound (C) 1.5779 g and compound (E) 1.1454 g, and the gas in the flask was replaced with nitrogen. 35 ml of toluene bubbled with argon was added to the flask, stirred and dissolved, and then bubbled with argon for 40 minutes. After raising the temperature of the bath for heating the flask to 85 ° C., 1.6 mg of palladium acetate and 6.7 mg of tris o-methoxyphenylphosphine were added to the reaction solution, and then the temperature of the bath was raised to 105 ° C. However, 9.5 ml of a 17.5% by weight aqueous sodium carbonate solution was added dropwise over 6 minutes. After dropping, the mixture was stirred for 1.7 hours while maintaining the bath temperature at 105 ° C., and then the reaction solution was cooled to room temperature.

  Next, 1.0877 g of compound (C) and 0.9399 g of compound (D) were added to the reaction solution, and 15 ml of toluene bubbled with argon was further added. After stirring and dissolving, argon was bubbled for another 30 minutes. To the reaction solution, 1.3 mg of palladium acetate and 4.7 mg of tris o-methoxyphenylphosphine were added, and then the temperature of the bath was raised to 105 ° C., and 6.8 ml of a 17.5 wt% sodium carbonate aqueous solution. Was added dropwise over 5 minutes. After the dropwise addition, the mixture was stirred for 3 hours while maintaining the bath temperature at 105 ° C. After stirring, 50 ml of argon bubbled toluene, 2.3 mg of palladium acetate, 8.8 mg of tris o-methoxyphenylphosphine, and 0.305 g of phenylboronic acid were added to the reaction solution, and the bath temperature was maintained at 105 ° C. The mixture was stirred for 8 hours. Next, after removing the aqueous layer of the reaction solution, an aqueous solution in which 3.1 g of sodium N, N-diethyldithiocarbamate was dissolved in 30 ml of water was added, and the mixture was stirred for 2 hours while maintaining the bath temperature at 85 ° C. . Subsequently, 250 ml of toluene was added to the reaction solution to separate the reaction solution, and the organic layer was washed twice with 65 ml of water, twice with 65 ml of 3% by weight aqueous acetic acid and twice with 65 ml of water. The washed organic layer was diluted by adding 150 ml of toluene, and dropped into 2500 ml of methanol to reprecipitate the polymer compound. The polymer compound was filtered, dried under reduced pressure, and dissolved in 500 ml of toluene. The obtained toluene solution was passed through a silica gel-alumina column, and the obtained toluene solution was added dropwise to 3000 ml of methanol to reprecipitate the polymer compound. The polymer compound was filtered and dried under reduced pressure to obtain 3.00 g of polymer 2. The obtained polymer 2 had a polystyrene equivalent weight average molecular weight of 257,000 and a number average molecular weight of 87,000.

Polymer 2 is
It is a block copolymer represented by the following formula.

(Production of Composition 1)
25 parts by weight of [6,6] -phenyl C71-butyric acid methyl ester (C70PCBM) (ADS71BFA manufactured by American Dye Source) as a fullerene derivative, 2.5 parts by weight of polymer 1 as an electron donor compound, 2.5 parts by weight of the polymer 2 and 1000 parts by weight of o-dichlorobenzene as a solvent were mixed. Next, the mixed solution was filtered through a Teflon (registered trademark) filter having a pore diameter of 1.0 μm to prepare a composition 1.

Example 1
(Production and evaluation of organic thin-film solar cells)
A glass substrate on which an ITO thin film functioning as a cathode of a solar cell was formed was prepared. The ITO thin film was formed by sputtering, and the thickness was 150 nm. A coating solution was prepared by mixing 1 part by weight of 20% by weight methyl ethyl ketone dispersion (Pazette GK, manufactured by Hakusui Tech Co., Ltd.) of gallium-doped zinc oxide nanoparticles (particle size: 20 nm to 40 nm) and 10 parts by weight of methyl ethyl ketone. This coating solution was applied onto ITO with a film thickness of 19 nm by spin coating, and heated in air at 120 ° C. for 10 minutes to form an oxide layer.
On the oxide layer, the composition 1 was applied by spin coating to form an active layer (film thickness of about 200 nm).

Next, a hole transporting layer was formed by applying a coating type hole transporting material HIL691 manufactured by Plextronics Co., Ltd. to a thickness of 50 nm on the active layer by spin coating and drying. Then, the organic thin-film solar cell was produced by vapor-depositing aluminum of an anode with a film thickness of 100 nm with a vacuum evaporation machine. The degree of vacuum at the time of vapor deposition was 1 to 9 × 10 ⁻³ Pa in all cases. Then, the organic thin film solar cell element was sealed with a glass plate using a UV curable sealant. The shape of the obtained organic thin film solar cell was a regular square of 2 mm × 2 mm. Using a solar simulator (trade name: OTENTO-SUNII: AM1.5G filter, irradiance: 100 mW / cm ² ), irradiate the obtained organic thin-film solar cell with a certain amount of light, and generate the generated current and voltage. The photoelectric conversion efficiency was measured by measuring. The photoelectric conversion efficiency was 4.36%, the short-circuit current density was 9.93 mA / cm ² , the open circuit voltage was 0.92 V, and the FF (fill factor) was 0.48.

Comparative Example 1
(Production and evaluation of organic thin-film solar cells)
Preparation and evaluation of organic thin-film solar cells)
A glass substrate on which an ITO thin film that functions as an anode of a solar cell was formed was prepared. The ITO thin film was formed by sputtering, and the thickness was 150 nm. 1 part by weight of a 45 wt% isopropanol dispersion (HTD-711Z, manufactured by Teika) of zinc oxide nanoparticles (particle size 20-30 nm) and 10 parts by weight of isopropanol were mixed to prepare a coating solution. This coating solution was applied onto ITO with a film thickness of 50 nm by spin coating, and heated in air at 120 ° C. for 10 minutes to form an oxide layer. On the oxide layer, the composition 1 was applied by spin coating to form an active layer (film thickness of about 200 nm).

Next, a hole transporting layer was formed by applying a coating type hole transporting material HIL691 manufactured by Plextronics Co., Ltd. to a thickness of 50 nm on the active layer by spin coating and drying. Then, the organic thin-film solar cell was produced by vapor-depositing aluminum of an anode with a film thickness of 100 nm with a vacuum evaporation machine. The degree of vacuum at the time of vapor deposition was 1 to 9 × 10 ⁻³ Pa in all cases. Then, the organic thin film solar cell element was sealed with a glass plate using a UV curable sealant. The shape of the obtained organic thin film solar cell was a regular square of 2 mm × 2 mm. Using a solar simulator (trade name: OTENTO-SUNII: AM1.5G filter, irradiance: 100 mW / cm ² ), the obtained organic thin film solar cell is irradiated with a certain amount of light, and the generated current and voltage are The photoelectric conversion efficiency was measured by measuring. The photoelectric conversion efficiency was 3.98%, the short-circuit current density was 8.68 mA / cm ² , the open-circuit voltage was 0.93 V, and the FF (fill factor) was 0.49.

Claims (4)

Forming a cathode;
Forming an oxide layer comprising zinc oxide doped with gallium on the cathode;
Forming an active layer on the oxide layer.   The method for producing an organic photoelectric conversion element according to claim 1, wherein the oxide layer is formed by coating a coating solution containing zinc oxide doped with gallium on a cathode.   The method for producing an organic photoelectric conversion element according to claim 1, wherein the zinc oxide doped with gallium is in the form of particles.   The method for producing an organic photoelectric conversion element according to claim 1, wherein the active layer contains fullerenes and / or derivatives of fullerenes and a conjugated polymer compound.