JP2013026432A - Organic photoelectric conversion element, method for manufacturing the same, and organic solar cell using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic photoelectric conversion element which has high photoelectric conversion efficiency and excellent durability, a method for manufacturing the same, and a solar cell using the organic photoelectric conversion element.SOLUTION: The organic photoelectric conversion element includes, between a first electrode 12 and a second electrode 13, a photoelectric conversion layer 14 and at least one of a hole transport layer 17 and an electron transport layer 18. The one of the hole transport layer 17 and the electron transport layer 18 contains an organic compound subjected to polymerization treatment in the presence of a metal compound.

Description

  The present invention relates to an organic photoelectric conversion element, and more particularly to an organic photoelectric conversion element that can be used for an organic solar cell, and more specifically, to an organic photoelectric conversion element that achieves both power generation performance and element durability and its manufacture. The present invention relates to a method and an organic solar cell using the method.

  Due to the recent rise in fossil energy, a system that can generate electric power directly from natural energy has been demanded. Solar cells using single crystal, polycrystal, and amorphous Si, GaAs, CIGS (copper (Cu), indium (In) ), Semiconductor materials such as gallium (Ga) and selenium (Se)), and dye-sensitized photoelectric conversion elements (Gretzel cells) have been proposed and put to practical use.

  However, the cost of generating electricity with these solar cells is still higher than the price of electricity generated and transmitted using fossil fuels, which has hindered widespread use. In addition, since heavy glass must be used for the substrate, reinforcement work is required at the time of installation, which is one of the causes that increase the power generation cost.

  For such a situation, as a solar cell that can achieve a power generation cost lower than that of fossil fuel, an electron donor layer (p-type semiconductor layer) and an electron acceptor layer (p-type semiconductor layer) are provided between the transparent electrode and the counter electrode. A bulk heterojunction photoelectric conversion element sandwiching a photoelectric conversion layer mixed with an n-type semiconductor layer) has been proposed, and a photoelectric conversion efficiency exceeding 5% has been reported (for example, see Non-Patent Document 1).

  Solar cells using these bulk heterojunction type photoelectric conversion elements can be formed by coating other than the anode and cathode, so that they can be manufactured at high speed and at low cost, and the above-mentioned problem of power generation cost can be solved. There is sex. Furthermore, unlike the Si-based solar cells, semiconductor-based solar cells, dye-sensitized solar cells, etc., since there is no manufacturing process at a temperature higher than 160 ° C., it is expected that it can be formed on a cheap and lightweight plastic substrate. Is done.

  However, for practical use, in addition to high efficiency, improvement in durability is also required. For such a problem, in a type of solar cell (so-called reverse layer type solar cell) in which a metal having a high work function, which is unlikely to deteriorate, is used as a counter electrode and the sunlight incident side is a cathode. Since it is known that the durability is improved (see, for example, Patent Document 1), a material capable of providing high photoelectric conversion efficiency in the reverse layer configuration is demanded.

  The photoelectric conversion efficiency of a bulk heterojunction photoelectric conversion element itself depends on the combination of the p-type semiconductor and n-type semiconductor of the photoelectric conversion layer, but in order to maximize the performance obtained by these combinations, hole transport Development of intermediate layers such as layers and electron transport layers is essential.

  For example, the open-circuit voltage (hereinafter also referred to as Voc) is determined by the difference between the HOMO of the p-type semiconductor and the n-type semiconductor LUMO, but in reality, a Voc greater than the difference in work function between the hole transport layer and the electron transport layer is obtained. Therefore, in order to obtain Voc as designed at the level, the work function difference between the hole transport layer and the electron transport layer needs to be designed to be greater than the difference between the HOMO of the p-type semiconductor and the n-type semiconductor LUMO. . In addition, since the internal electric field in the device is enhanced by increasing the work function difference of the intermediate layer, the rectification and the fill factor (FF) are improved, and high efficiency is expected.

  Therefore, it is required that the electron transport layer has a shallower work function and the hole transport layer has a deeper work function regardless of the configuration of the photoelectric conversion element.

  Until now, several methods for preparing a work function by doping a metal salt or the like in an intermediate layer have been known (for example, Non-Patent Documents 2 and 3).

JP 2009-146981 A

A. Heeger et. al. , Nature Mat. , Vol. 6 (2007), p497 Mi-Hyae Park et al. , Adv. Funct. Mater. 2009, 19, 1241-1246 Y. Sato et. al. , Thin Solid Film. , Vol. 516 (2008), p5758-5762

  However, the device in which the intermediate layer is doped with a metal salt or the like and the work function is adjusted by the dopant is a result of intensive studies by the present inventors, and as a result, the performance of the photoelectric conversion device is significantly deteriorated by long-time light irradiation. I understood. This is considered because the dopant has diffused into the photoelectric conversion layer over time.

  This invention is made | formed in view of the said subject, The objective provides the photoelectric conversion element with the high photoelectric conversion efficiency and the durability, the manufacturing method, and the solar cell using the organic photoelectric conversion element. There is.

  Even when the work function is controlled using a dopant in the hole transport layer and the electron transport layer, the present inventors suppress the diffusion of the dopant into the photoelectric conversion layer if the layer containing the dopant is polymerized. It was found that both high efficiency and high durability of the organic photoelectric conversion element can be achieved.

  1. In the organic photoelectric conversion element having a photoelectric conversion layer and at least one of a hole transport layer or an electron transport layer between the first electrode and the second electrode, at least one of the hole transport layer or the electron transport layer is An organic photoelectric conversion element comprising an organic compound polymerized in the presence of a metal compound.

  2. 2. The organic photoelectric conversion element as described in 1 above, wherein the metal compound is a metal salt or a metal oxide.

  3. 3. The organic photoelectric conversion device as described in 1 or 2 above, wherein in the polymerization treatment, the treatment method is thermal polymerization.

  4). 4. The organic photoelectric conversion element according to any one of 1 to 3, wherein the metal oxide contained in the hole transport layer is a metal salt or metal oxide of V or Mo.

  5). 4. The organic photoelectric conversion element according to any one of 1 to 3, wherein the metal salt contained in the electron transport layer is a metal salt of Cs and Li.

  6). The hole transport layer is a layer containing a metal oxide, the electron transport layer is a layer containing a metal salt, and both layers each contain a polymerized organic compound. 6. The organic photoelectric conversion element according to any one of 1 to 5, wherein:

  7). 7. The organic solar battery comprising the organic photoelectric conversion element according to any one of 1 to 6, wherein the first electrode is a cathode and the second electrode is an anode.

  8). It is a manufacturing method of the organic photoelectric conversion element which manufactures the organic photoelectric conversion element of any one of said 1-6, Comprising: It superposes | polymerizes in presence of the compound which has a metal compound and a reactive group, A method for producing an organic photoelectric conversion element.

  According to the present invention, an organic photoelectric conversion element having a high fill factor (FF) and a high open-circuit voltage (Voc), high photoelectric conversion efficiency and excellent durability, a manufacturing method thereof, and the organic photoelectric conversion element The used solar cell can be provided.

It is a schematic sectional drawing which shows the example of a structure of the normal layer type organic photoelectric conversion element of this invention. It is a schematic sectional drawing which shows the example of a structure of the reverse layer type organic photoelectric conversion element of this invention. It is a schematic sectional drawing which shows the example of the organic photoelectric conversion element of this invention provided with the tandem type photoelectric conversion layer.

  The present invention relates to an organic photoelectric conversion device having a photoelectric conversion layer and at least one of a hole transport layer and an electron transport layer between a first electrode and a second electrode. The invention relates to an organic photoelectric conversion element, wherein at least one of the layers contains a metal compound and is polymerized. According to the present invention, an organic photoelectric conversion element having a high fill factor (FF) and a high open-circuit voltage (Voc), high photoelectric conversion efficiency, and excellent durability can be provided.

  In the present invention, as a result of intensive studies by the present inventors, even when the work function is controlled using a metal compound in at least one of the hole transport layer and the electron transport layer, the layer having the metal compound is simultaneously polymerized. As a result, the diffusion of the metal compound into the photoelectric conversion layer over time can be suppressed, and it has been found that an element having both high efficiency and high durability can be obtained.

(Configuration of organic photoelectric conversion element)
FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a normal layer type organic photoelectric conversion element according to the present invention.

  The organic photoelectric conversion element 10 has a first electrode 12 on a substrate 11, a hole transport layer 17 on the first electrode 12, and a photoelectric conversion layer 14 on the hole transport layer 17. The electron transport layer 18 is provided on the photoelectric conversion layer 14, and the second electrode 13 is provided on the electron transport layer 18.

  As one embodiment of the present invention, the substrate 11 and the first electrode 12 are transparent, and light used for photoelectric conversion enters from the direction of the arrow in FIG.

  The photoelectric conversion layer 14 is a layer that converts light energy into electrical energy, and contains a p-type semiconductor material and an n-type semiconductor material.

  The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor).

  Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

  In FIG. 1, light incident from the first electrode 12 through the substrate 11 is absorbed by the electron acceptor or the electron donor in the photoelectric conversion layer 14 of the photoelectric conversion layer 14, and from the electron donor to the electron acceptor. Electrons move and a hole-electron pair (charge separation state) is formed.

  The generated electric charge is generated between the electron acceptors due to the internal electric field, for example, when the work functions of the first electrode 12 and the second electrode 13 are different, due to the potential difference between the first electrode 12 and the second electrode 13. And the holes pass between the electron donors and are carried to different electrodes, and a photocurrent is detected.

  In the example of FIG. 1, the work function of the first electrode 12 is larger than the work function of the second electrode 13, so that holes are transported to the first electrode 12 and electrons are transported to the second electrode 13. In this case, the second electrode 13 is made of a metal that has a small work function and is easily oxidized. In this case, the first electrode functions as an anode (anode) and the second electrode functions as a cathode (cathode).

  FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a reverse layer type organic photoelectric conversion element according to the present invention.

  In FIG. 2, contrary to the case of FIG. 1, the work function of the second electrode 13 is made larger than the work function of the first electrode 12, whereby electrons are transferred to the first electrode 12. The case where it designed so that it might convey to the 2nd electrode 13 was shown. In this case, the electron transport layer 18 is provided between the first electrode 12 and the photoelectric conversion layer 14, and the hole transport layer 17 described later is provided between the photoelectric conversion layer 14 and the second electrode 13. The first electrode functions as a cathode (cathode) and the second electrode functions as an anode (anode).

  In the present invention, from the viewpoint of durability of the second electrode, the configuration shown in FIG. 2 in particular, that is, the first electrode is a cathode (cathode) and the second electrode is an anode (anode). This is a preferred embodiment. The organic photoelectric conversion element used for the solar cell of the present invention preferably has the configuration shown in FIG.

  Although not shown in FIGS. 1 and 2, the organic photoelectric conversion element of the present invention has a layer such as a hole blocking layer, an electron blocking layer, an electron injection layer, a hole injection layer, or a smoothing layer. You may have.

  Furthermore, it is good also as a tandem-type structure which laminated | stacked such a photoelectric conversion element for the purpose of the improvement of sunlight utilization factor (photoelectric conversion efficiency). FIG. 3 is a cross-sectional view illustrating an organic photoelectric conversion element including a tandem photoelectric conversion layer.

  In the case of the tandem configuration, the first electrode 12 and the first photoelectric conversion layer 14 ′ are stacked on the substrate 11, the charge recombination layer 15 is stacked, the second photoelectric conversion layer 16, and then the second By stacking the electrodes 13, a tandem configuration can be obtained.

  The second photoelectric conversion layer 16 may be a layer that absorbs the same spectrum as the absorption spectrum of the first photoelectric conversion layer 14 'or may be a layer that absorbs a different spectrum, but is preferably a layer that absorbs a different spectrum. is there.

  Further, a hole transport layer 17 and an electron transport layer 18 may be provided between the first photoelectric conversion layer 14 'and the second photoelectric conversion layer 16 and each electrode. Also in the configuration, each photoelectric conversion layer preferably has a configuration as shown in FIG.

  Hereinafter, the present invention will be described in detail.

[Metal compounds]
In the present invention, a metal compound is used as a dopant for adjusting the work function of the hole transport layer or the electron transport layer. When a dopant is added to the electron transport layer or the hole transport layer, an impurity level due to the dopant is formed in the layer, so that the level can be arbitrarily changed.

  The metal compound in the present invention is selected from the following inorganic metal compounds or organometallic compounds, but is not limited thereto. Examples of inorganic metal compounds include halides, oxides, sulfides, nitrides, and carbonates. Organometallic compounds include formate, acetate, propionic acid, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, succinate, benzoate, Phthalate, isophthalate, terephthalate, salicylate, pyruvate, lactate, malate, adipate, mesylate, tosylate, benzenesulfonate, preferably formate , Acetate, propionate, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, succinate, benzoate, more preferably formate, acetic acid Examples thereof include aliphatic carboxylates such as salts and propionates.

  As the electron transport layer, a material having an effect of reducing the work function can be used as a dopant. As the metal compound used for the electron transport layer, a metal salt is preferably used among inorganic metal compounds and organic metal compounds. As the metal of the metal salt, an alkali metal is preferably used. The type of alkali metal is not particularly limited, and examples thereof include Li, Na, K, and Cs, preferably Li, Cs, and more preferably Cs. Examples of the metal compound include Li fluoride, K fluoride, Na fluoride, C fluoride, Li carbonate, K carbonate, Na carbonate, Cs, formic acid Li, formic acid K, formic acid Na, formic acid Cs, Li acetate, and K acetate. , Na acetate, Cs, Li propionate, Na propionate, K propionate, C propionate, Li oxalate, Na oxalate, K oxalate, Cs, Li malonate, Na malonate, K malonic acid , Malonic acid Cs, succinic acid Li, succinic acid Na, succinic acid K, succinic acid Cs, benzoic acid Li, benzoic acid Na, benzoic acid K, benzoic acid Cs, preferably Li carbonate, K carbonate, Na carbonate Carbonic acid Cs, Li acetate, K acetate, Na acetate, Cs acetate, and most preferably Cs carbonate and Cs acetate.

  As the hole transport layer, one having an effect of deepening the work function can be used as a dopant. Examples of the metal of the metal compound used for the hole transport layer include V, Nb, Mo and Ti, preferably V, Mo and Ti, more preferably Mo and V.

Examples of the metal compound used for the hole transport layer include metal oxides, and specifically, MoO ₂ , MoO ₃ , TiO, TiO ₂ , NbO, V ₂ O ₅ , Nb ₂ O ₅ , VF ₃ , TiCl ₂ , NbCl ₅ , VCl ₃ , NbB ₂ , VBr ₃ , VI ₃ , VCl ₃ O, MoS ₂ may be mentioned. Preferred are MoO ₂ , TiO ₂ , V ₂ O ₅ and MoS ₂ , and most preferred are MoO ₂ and V ₂ O ₅ .

  As addition amount of a metal compound, it is 1.5-35 mass% of the electron carrying layer and hole transport layer to add, More preferably, it is 3-25 mass%, Most preferably, it is 5-15 mass%. .

[Polymerization treatment, polymerization material]
The present invention is characterized in that at least one of the hole transport layer and the electron transport layer contains an organic compound polymerized in the presence of the metal compound. The polymerization treatment in the present invention refers to treatment so that an organic polymerization material is polymerized.

  The organic polymer material according to the present invention is defined as a compound having at least one reactive group. Examples of the reactive group include a vinyl group, an epoxy group, an oxetane group, and an isocyanate group. Although the specific example of a reactive group is given to the following, this invention is not limited to these.

  Among these, a vinyl group and an epoxy group that can be polymerized by heat at a relatively low temperature are preferably used. The polymerization reaction according to the present invention is performed by energy irradiation. Examples of the irradiation energy include ultraviolet light, electrons, ions, heat, radical beam, or radiation energy. Polymerization with heat is preferably used because it has little influence on other organic layers.

  In the present invention, an insolubilized layer can be obtained by polymerizing a compound having at least one reactive group, but in order to adjust the degree of polymerization, the polymerization reaction of monomers under a polymerization condition where the reaction is likely to stop. Can be easily obtained. For example, the polymerization initiator or catalyst concentration is controlled, a chain transfer agent or a polymerization terminator is used in combination, or the irradiation energy of ultraviolet rays, electrons, ions, heat, radical beams or radiation is controlled.

  The polymerization treatment needs to be performed in the presence of a metal compound, but it may be performed at any stage of preparing a coating solution for forming a hole transport layer or an electron transport layer. Polymerization treatment may be performed after forming the hole transport layer or the electron transport layer.

  Examples of the compound having a reactive group include styrene, methyl methacrylate, -2-hydroxyethyl acrylate, acrylamide, acrylonitrile, trimethylolpropane triglycidyl ether (TMPTGE), glycerol propoxylate triglycidyl ether (DEG), Threebond 3101 (manufactured by Three Bond Co., Ltd., ultraviolet curable resin) can be used.

(Electron transport layer)
The electron transport layer is a layer that is located between the cathode and the photoelectric conversion layer and can more efficiently transfer electrons between the photoelectric conversion layer and the electrode. The present invention can be particularly preferably applied when the first electrode is a cathode.

  In the present invention, it is preferable that the electron transport layer has a metal compound so as to have a shallow work function and is polymerized. The work function in the electron transport layer refers to the HOMO-LUMO level of the electron transport layer itself. However, when the work function of the adjacent electrode is changed by stacking the electron transport layer of a very thin film like a monomolecular film, the work function of the electrode The work function is described as the work function of the electron transport layer.

  In the electron transport layer, the electron transport layer having a HOMO level deeper than the HOMO level of the p-type semiconductor material used in the bulk heterojunction type photoelectric conversion layer includes a hole generated in the bulk heterojunction layer as a cathode. A hole blocking function having a rectifying effect that does not flow to the side is provided.

Such an electron transport layer is also referred to as a hole blocking layer. More preferably, a material having a HOMO level deeper than the HOMO level of the n-type semiconductor is used for the electron transport layer. Moreover, it is preferable to use the compound whose hole mobility is lower than 10 ^<-6> from the characteristic which blocks a hole.

As the electron transport layer, octaazaporphyrin, p-type semiconductor perfluoro compounds (perfluoropentacene, perfluorophthalocyanine, etc.), carboline compounds described in International Publication No. 04/095889, and the like can be used. The electron transport layer having a HOMO level deeper than the HOMO level of the p-type semiconductor material used for the photoelectric conversion layer has a rectifying effect so that holes generated in the photoelectric conversion layer do not flow to the cathode side. The hole blocking function is imparted. More preferably, a material deeper than the HOMO level of the n-type semiconductor is used as the electron transport layer. Moreover, it is preferable to use a compound with high electron mobility from the characteristic of transporting electrons. More preferably, it is a compound having an electron mobility of 10 ⁻⁴ or more.

  Examples of such materials include phenanthrene compounds such as bathocuproine, n-type semiconductor materials such as naphthalenetetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, and perylenetetracarboxylic acid diimide, and WO2001343442. An amine compound such as an amine-based silane coupling agent and an n-type inorganic oxide such as titanium oxide, zinc oxide, or gallium oxide can be used. Moreover, the layer which consists of a n-type semiconductor material single-piece | unit used for the photoelectric converting layer can also be used.

  The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method.

[Hole transport layer (electron blocking layer)]
The hole transport layer is a layer that is located between the anode and the photoelectric conversion layer, and that can transfer holes more efficiently between the photoelectric conversion layer and the electrode. The present invention can be particularly preferably applied when the first electrode is an anode.

  In the present invention, it is preferable that the hole transport layer has a metal compound to increase the work function and is polymerized. The work function in the hole transport layer refers to the HOMO-LUMO level of the hole transport layer itself. However, when the work function of the adjacent electrode is changed by stacking the electron transport layer of a very thin film like a monomolecular film, The work function of the electrode was described as the work function of the hole transport layer. The highest occupied orbital (HOMO) level of the hole transport material and the work function of the transparent electrode surface can be determined by using, for example, a photoelectron emission measurement method (UPS).

  As a material constituting these layers, for example, as a hole transport layer, PEDOT (poly-3,4-ethylenedioxythiophene) -PSS (polystyrene sulfonic acid) such as Stark Vitec, trade name BaytronP, Polyaniline and a doping material thereof, cyan compounds described in International Publication No. 06/019270, and the like can be used. Note that the hole transport layer having a LUMO level shallower than the LUMO level of the n-type semiconductor material used for the photoelectric conversion layer has a rectifying effect that prevents electrons generated in the photoelectric conversion layer from flowing to the anode side. It has an electronic block function. Such a hole transport layer is also called an electron block layer, and it is preferable to use a hole transport layer having such a function.

  As such a material, a triarylamine compound described in JP-A-5-271166 or a metal oxide such as molybdenum oxide, nickel oxide, or tungsten oxide can be used. Moreover, the layer which consists of a p-type semiconductor material single-piece | unit used for the photoelectric converting layer can also be used. In addition to the materials described above, it is also possible to use inorganic materials such as silver nanoparticles. Moreover, these inorganic materials may be used individually by 1 type, and may use 2 or more types together. The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method. Forming a coating film in the lower layer before forming the photoelectric conversion layer is preferable because it has the effect of leveling the coating surface and reduces the influence of leakage and the like.

Similarly, it preferably has a hole mobility higher than 10 ⁻⁴ due to the property of transporting holes, and a compound with electron mobility lower than 10 ⁻⁶ due to the property of blocking electrons. It is preferable to use it.

[Other layers]
As a structure of the organic photoelectric conversion element of this invention, it is good also as a structure which has various intermediate | middle layers in an element for the purpose of the improvement of a photoelectric conversion efficiency, and the improvement of element lifetime.

  Examples of the intermediate layer include a hole block layer, an electron block layer, a hole injection layer, an electron injection layer, an exciton block layer, a UV absorption layer, a light reflection layer, and a wavelength conversion layer.

(Photoelectric conversion layer)
The photoelectric conversion layer has a function of converting light energy into electric energy using the photovoltaic effect. The photoelectric conversion layer contains a p-type organic semiconductor material and an n-type organic semiconductor material as a photoelectric conversion material. When light is absorbed by these photoelectric conversion materials, excitons are generated, which are separated into holes and electrons at the pn junction interface.

  The p-type organic semiconductor material used for the photoelectric conversion layer according to the present invention contains a p-type conjugated polymer. This p-type conjugated polymer is a copolymer having an electron donating group (donor unit) and an electron withdrawing group (acceptor unit) in the main chain. More specifically, the p-type conjugated polymer has a structure in which donor units and acceptor units are alternately arranged. Thus, by arranging the donor unit and the acceptor unit alternately, the absorption region of the p-type organic semiconductor can be expanded to a long wavelength region. That is, the p-type conjugated polymer can absorb light in a long wavelength region (for example, 700 to 100 nm) in addition to the absorption region (for example, 400 to 700 nm) of a conventional p-type organic semiconductor. It becomes possible to efficiently absorb radiant energy over a wide range of the optical spectrum.

  The donor unit that can be included in the p-type conjugated polymer is a unit in which the LUMO level or the HOMO level is shallower than a hydrocarbon aromatic ring (benzene, naphthalene, anthracene, etc.) having the same number of π electrons. If there is, it can be used without restriction. For example, a unit including a thiophene ring, a furan ring, a pyrrole ring, a hetero 5-membered ring such as cyclopentadiene or silacyclopentadiene, and a condensed ring thereof.

  Specific examples include fluorene, silafluorene, carbazole, dithienocyclopentadiene, dithienosylcyclopentadiene, dithienopyrrole, and benzodithiophene.

  The donor unit preferably has a structure represented by the following chemical formula 1.

In the formula, Z ₁ represents a carbon atom, a silicon atom, or germanium, and each R ₁ independently represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substitution having 1 to 20 carbon atoms. Or an unsubstituted fluorinated alkyl group, a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or non-substituted group having 1 to 20 carbon atoms It represents a substituted heteroaryl group, or a substituted or unsubstituted alkylsilyl group having 1 to 20 carbon atoms, and two R _{1 's} may be bonded to each other to form a ring. R ₁ may be different from each other.

  A structure represented by the following chemical formula 2 is also suitable as the donor unit.

In the formula, each R ₂ independently represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkyl ether group having 1 to 20 carbon atoms, or 1 to 20 carbon atoms. In the formula (1), a substituted or unsubstituted alkyl ester group, and two R ₂ may be bonded to each other to form a ring. R ₂ may be different from each other.

  In the above chemical formulas 1 and 2, the substituent that may be present in the alkyl group, the fluorinated alkyl group, the cycloalkyl group, the aryl group, the heteroaryl group, or the alkylsilyl group may be, for example, a halogen atom (fluorine atom) , Chlorine atom, bromine atom, iodine atom), acyl group, alkyl group, phenyl group, alkoxyl group, halogenated alkyl group, halogenated alkoxyl group, nitro group, amino group, alkylamino group, alkylcarbonylamino group, arylamino Group, arylcarbonylamino group, carbonyl group, alkoxycarbonyl group, alkylaminocarbonyl group, alkoxysulfonyl group, alkylthio group, carbamoyl group, aryloxycarbonyl group, oxyalkylether group, cyano group, etc. The present invention is not limited to.

  The donor unit represented by the above chemical formulas 1 and 2 has a solubility imparted by a substituent while the thiophene structure having a high mobility is condensed to have a large π-conjugated plane. Since such a donor unit is excellent in both solubility and mobility, the photoelectric conversion efficiency can be further improved.

  On the other hand, acceptor units that can be included in the p-type conjugated polymer include, for example, quinoxaline skeleton, pyrazinoquinoxaline skeleton, benzothiadiazole skeleton, benzooxadiazole skeleton, benzoselenadiazole skeleton, benzotriazole skeleton, pyrido Thiadiazole skeleton, thienopyrazine skeleton, phthalimide skeleton, 3,4-thiophenedicarboxylic acid imide skeleton, isoindigo skeleton, thienothiophene skeleton, diketopyrrolopyrrole skeleton, 4-acyl-thieno [3,4-b] thiophene skeleton, pyrazolo [ 5,1-c] [1,2,4] triazole skeleton and the like. In addition, the donor unit or acceptor property contained in the p-type conjugated polymer of this embodiment may be used alone or in combination of two or more.

  In the present embodiment, preferable p-type conjugated polymers include Nature Material, (2006) vol. 5, p328, polythiophene-thienothiophene copolymer, polythiophene-diketopyrrolopyrrole copolymer described in WO08 / 000664, Adv. Mater. , 2007, p4160, a polythiophene-thiazolothiazole copolymer, Nature Mat. vol. 6 (2007), p497, and a polythiophene copolymer such as PCPDTBT. Of these, polythiophene copolymers such as the following PCPDTBT are particularly preferred.

  The molecular weight of the p-type conjugated polymer is not particularly limited, but the number average molecular weight is preferably 5,000 to 500,000, more preferably 10,000 to 100,000, and further preferably 15,000 to 50,000. When the number average molecular weight is 5000 or more, the effect of improving the fill factor becomes more remarkable. On the other hand, when the number average molecular weight is 500000 or less, the solubility of the p-type conjugated polymer is improved, so that productivity can be increased. In addition, in this specification, the value measured by gel permeation chromatography (GPC) is employ | adopted for a number average molecular weight.

  In addition, although the photoelectric converting layer in this invention has the p-type conjugated polymer mentioned above, it may also contain other p-type organic-semiconductor materials. Examples of such other p-type organic semiconductor materials include triarylamine compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, Cyanine compounds, merocyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, Fluoranthene derivatives) and metal complexes having a nitrogen-containing heterocyclic compound as a ligand. However, from the viewpoint of remarkably expressing the effects of the present invention, the mass ratio of the p-type conjugated polymer in the p-type organic semiconductor material contained in the photoelectric conversion layer is preferably 5% by mass or more, More preferably, it is 10 mass% or more, More preferably, it is 50 mass% or more, Especially preferably, it is 90 mass% or more, Most preferably, it is 100 mass%.

  In the present invention, the band gap of the p-type organic semiconductor material contained in the photoelectric conversion layer is preferably 1.8 eV or less, and more preferably 1.6 to 1.1 eV. When the band gap is 1.8 eV or less, sunlight can be widely absorbed. On the other hand, when the band gap is 1.1 eV or more, the open circuit voltage Voc (V) is easily generated, and the conversion efficiency can be improved. In this embodiment, the p-type organic semiconductor may be used alone or in combination of two or more.

  On the other hand, the n-type organic semiconductor material used for the photoelectric conversion layer of this embodiment is not particularly limited as long as it is an acceptor (electron-accepting) organic compound. Can do. As such a compound, for example, a perfluoro product in which a hydrogen atom of the p-type organic semiconductor material is substituted with a fluorine atom, such as fullerene, carbon nanotube, and octaazaporphyrin (for example, perfluoropentacene or perfluorophthalocyanine), Examples thereof include aromatic carboxylic acid anhydrides such as naphthalenetetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, and perylenetetracarboxylic acid diimide, and polymer compounds containing an imidized product thereof as a skeleton.

  Of these, fullerenes, carbon nanotubes, or derivatives thereof are preferably used from the viewpoint that charge separation can be efficiently performed with a p-type organic semiconductor material at high speed (up to 50 fs). More specifically, fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C84, fullerene C240, fullerene C540, mixed fullerene, fullerene nanotube, multi-walled carbon nanotube, single-walled carbon nanotube, carbon nanohorn (conical type), etc. , And some of these are hydrogen atoms, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), substituted or unsubstituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups, And a fullerene derivative substituted with a cycloalkyl group, a silyl group, an ether group, a thioether group, an amino group, or the like.

  In particular, [6,6] -phenyl C61-butyric acid methyl ester (abbreviation PCBM), [6,6] -phenyl C61-butyric acid-nbutyl ester (PCBnB), [6,6] -phenyl C61- Butyric acid-isobutyl ester (PCBiB), [6,6] -phenyl C61-butyric acid-n hexyl ester (PCBH), [6,6] -phenyl C71-butyric acid methyl ester (abbreviation PC71BM), Adv . Mater. , Vol. 20 (2008), p2116, aminated fullerene described in JP-A 2006-199674, metallocene fullerene described in JP-A 2008-130889, US Pat. No. 7,329,709 It is preferable to use a fullerene derivative whose solubility is improved by a substituent, such as fullerene having a cyclic ether group described in the specification. In this embodiment, the n-type organic semiconductor material may be used alone or in combination of two or more.

  The junction form of the p-type organic semiconductor and the n-type organic semiconductor in the photoelectric conversion layer of this embodiment is not particularly limited, and may be a planar heterojunction or a bulk heterojunction. A planar heterojunction is a junction in which a p-type organic semiconductor layer containing a p-type organic semiconductor and an n-type organic semiconductor layer containing an n-type organic semiconductor are stacked, and the surface where these two layers contact is the pn junction interface. It is a form. On the other hand, a bulk heterojunction (bulk heterojunction) is formed by applying a mixture of a p-type organic semiconductor and an n-type organic semiconductor, and the domain of the p-type organic semiconductor and the n-type organic semiconductor in this single layer. And have a microphase separation structure. Therefore, in a bulk heterojunction, as compared with a planar heterojunction, many pn junction interfaces exist over the entire layer. Therefore, most of the excitons generated by light absorption can reach the pn junction interface, and the efficiency leading to charge separation can be increased. For these reasons, the junction between the p-type organic semiconductor and the n-type organic semiconductor in the photoelectric conversion layer of this embodiment is preferably a bulk heterojunction.

  In the present invention, the mixing ratio of the p-type organic semiconductor material and the n-type organic semiconductor material contained in the photoelectric conversion layer is preferably in the range of 2: 8 to 8: 2, more preferably 4: 6 to 6 in terms of mass ratio. : 4 range. Moreover, the film thickness of a photoelectric converting layer becomes like this. Preferably it is 50-400 nm, More preferably, it is 80-300 nm.

〔electrode〕
The organic photoelectric conversion element of the present invention has the first electrode and the second electrode. When the tandem configuration is adopted, the tandem configuration can be achieved by using the intermediate electrode.

  In the present invention, the first electrode is preferably a transparent electrode.

  “Transparent” means that the light transmittance is 50% or more.

  The light transmittance is the total light transmittance in the visible light wavelength region measured by a method according to “Testing method of total light transmittance of plastic-transparent material” of JIS K 7361-1 (corresponding to ISO 13468-1). Say.

  The first electrode of the present invention is preferably a transparent cathode (cathode) as described above, and the second electrode is preferably an anode (anode).

[First electrode]
Examples of the material used for the first electrode of the present invention include transparent metal oxides such as indium tin oxide (ITO), AZO, FTO, SnO ₂ , ZnO, and titanium oxide, Ag, Al, Au, and Pt. A very thin metal layer, a metal nanowire, a nanowire such as a carbon nanotube or a layer containing nanoparticles, a conductive polymer material such as PEDOT: PSS, polyaniline, or the like can be used.

  Also selected from the group consisting of derivatives of polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polyphenylacetylene, polydiacetylene and polynaphthalene. Conductive polymers can also be used. Further, a plurality of these conductive compounds can be combined to form a cathode.

[Second electrode]
The second electrode may be a single layer of a conductive material, but in addition to a conductive material, a resin that holds these may be used in combination.

  Since the work function of the transparent electrode, which is the cathode, is approximately −5.0 to −4.0 eV, the built-in potential is necessary for the carriers generated in the bulk heterojunction photoelectric conversion layer to diffuse and reach each electrode. That is, it is preferable that the work function difference between the anode and the cathode is as large as possible.

  Therefore, as the conductive material for the anode, a material having a work function (4 eV or less) metal, alloy, electrically conductive compound and a mixture thereof as an electrode material is used. Specific examples of such an electrode material include gold, silver, copper, platinum, rhodium, indium, nickel, palladium, and the like.

  Among these, silver is most preferable from the viewpoints of hole extraction performance, light reflectance, and durability against oxidation.

  The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

  In addition, when the anode side is made light transmissive, for example, a conductive material suitable for the anode such as aluminum and aluminum alloy, silver and silver compound is made thin with a film thickness of about 1 to 20 nm, and then the transparent electrode A light-transmitting anode can be obtained by providing the conductive light-transmitting material film mentioned in the description.

  In the above description, preferred materials for the second electrode material for making a so-called reverse layer type element, which is advantageous for improving durability, have been described. ), The relationship between the work functions of the first electrode and the second electrode may be reversed as described above, but the types of substantially transparent electrodes are limited, and the work functions are compared. In many cases, a deep layer organic thin film solar cell can be obtained by using a metal having a shallow work function (less than −4.0 eV) on the second electrode side. Examples of such metal include aluminum, calcium, magnesium, lithium, sodium, potassium, and the like. In general, aluminum having high reflectivity and high conductivity is used. Further, the second electrode may be a transparent electrode. “Transparent” has the same meaning as described above for the first electrode.

[Intermediate electrode]
Further, the material of the intermediate electrode required in the case of the tandem configuration as shown in FIG. 3 is preferably a layer using a compound having both transparency and conductivity. Transparent metal oxides such as ITO, AZO, FTO, SnO ₂ , ZnO and titanium oxide, very thin metal layers such as Ag, Al, Au and Pt, or layers containing nanowires and nanoparticles such as metal nanowires and carbon nanotubes PEDOT: PSS, conductive polymer materials such as polyaniline, etc.) can be used.

  In addition, in the hole transport layer and the electron transport layer described above, there is also a combination that works as an intermediate electrode (charge recombination layer) by appropriately combining and laminating. Is preferable.

[Transparent substrate]
In the present invention, the substrate is a transparent substrate, but “transparent” has the same meaning as described for the first electrode.

  As the substrate, for example, a glass substrate, a resin substrate, and the like are preferably exemplified, but it is desirable to use a transparent resin film from the viewpoint of lightness and flexibility. There is no restriction | limiting in particular in the transparent resin film which can be preferably used as a transparent substrate by this invention, The material, a shape, a structure, thickness, etc. can be suitably selected from well-known things.

  For example, polyolefins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyester resin film such as modified polyester, polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, cyclic olefin resin, etc. Resin films, vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyether ether ketone (PEEK) resin films, polysulfone (PSF) resin films, polyether sulfone (PES) resin films, polycarbonate (PC) resin films , Polyamide resin film, polyimide resin film, acrylic resin film, triacetyl cellulose (TAC) resin film, and the like. If the resin film transmittance of 80% or more in from zero to eight hundred nanomolar), can be preferably applied to a transparent resin film according to the present invention.

  Among them, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film. More preferred are a stretched polyethylene terephthalate film and a biaxially stretched polyethylene naphthalate film.

  The transparent substrate used in the present invention can be subjected to a surface treatment or an easy adhesion layer in order to ensure the wettability and adhesiveness of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment. Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

  Further, for the purpose of suppressing the permeation of oxygen and water vapor, a barrier coat layer may be formed in advance on the transparent substrate, or a hard coat layer may be formed in advance on the opposite side to which the transparent conductive layer is transferred. Good.

(Optical function layer)
The organic photoelectric conversion element of the present invention may have various optical functional layers for the purpose of more efficient reception of sunlight. As the optical functional layer, for example, a light condensing layer such as an antireflection film or a microlens array, a light diffusing layer that can scatter the light reflected by the cathode and enter the power generation layer again may be provided. .

  Various known antireflection layers can be provided as the antireflection layer. For example, when the transparent resin film is a biaxially stretched polyethylene terephthalate film, the refractive index of the easy adhesion layer adjacent to the film is 1.57. It is more preferable to set it to ˜1.63 because the interface reflection between the film substrate and the easy adhesion layer can be reduced and the transmittance can be improved. The method of adjusting the refractive index can be carried out by appropriately adjusting the ratio of the oxide sol having a relatively high refractive index such as tin oxide sol or cerium oxide sol and the binder resin. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion.

  As the condensing layer, for example, it is processed so as to provide a structure on the microlens array on the sunlight receiving side of the support substrate, or the amount of light received from a specific direction is increased by combining with a so-called condensing sheet. Conversely, the incident angle dependency of sunlight can be reduced.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  Examples of the light scattering layer include various antiglare layers, layers in which nanoparticles or nanowires such as metals or various inorganic oxides are dispersed in a colorless and transparent polymer, and the like.

[Patterning]
The method and process for patterning each electrode, photoelectric conversion layer, hole transport layer, electron transport layer and the like according to the present invention are not particularly limited, and known methods can be appropriately applied.

  If it is a soluble material such as a photoelectric conversion layer and a transport layer, only unnecessary portions may be wiped after the entire surface of die coating, dip coating, etc., or patterning is directly performed at the time of coating using a method such as an ink jet method or screen printing. May be.

  In the case of an insoluble material such as an electrode material, the electrode can be subjected to mask vapor deposition during vacuum deposition or patterned by a known method such as etching or lift-off. Alternatively, the pattern may be formed by transferring a pattern formed on another substrate.

[Solar cell]
The solar cell of this invention has said organic photoelectric conversion element.

  The solar cell of the present invention comprises the above-described organic photoelectric conversion element, has a structure in which optimum design and circuit design are performed for sunlight, and optimum photoelectric conversion is performed when sunlight is used as a light source. .

  That is, the photoelectric conversion layer has a structure that can be irradiated with sunlight, and when the solar cell of the present invention is configured, the photoelectric conversion layer and each electrode are housed in a case and sealed, Alternatively, it is preferable to seal them entirely with resin.

  As a sealing method, since the produced organic photoelectric conversion element is not deteriorated by oxygen, moisture, etc. in the environment, it is preferable to seal not only the organic photoelectric conversion element but also an organic electroluminescence element by a known method. .

  For example, a method of sealing a cap made of aluminum or glass by bonding with an adhesive, a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed and an organic photoelectric conversion element are pasted with an adhesive. Method, spin coating of organic polymer material with high gas barrier property (polyvinyl alcohol, etc.), inorganic thin film with high gas barrier property (silicon oxide, aluminum oxide, etc.) or organic film (parylene etc.) are deposited under vacuum. Examples thereof include a method and a method of laminating these in a composite manner.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

(Preparation of electron transport layer solution)
(Preparation of electron transport layer solution ETL-1)
ETL-1 was prepared by placing 7.0 mg of Ti isopropoxide in 1 ml of ethanol and stirring at room temperature throughout the day.

(Preparation of electron transport layer liquid ETL-2)
ETL-2 was prepared in the same manner as ETL-1, except that 10% by mass of CsCO ₃ was added to Ti isopropoxide.

(Preparation of electron transport layer liquid ETL-3)
ETL-3 was prepared by mixing 20 mg of polyethyleneimine (PEI) and 20 mg of glycerol propoxylate triglycidyl ether in 1 ml of isopropanol and stirring for 30 minutes.

(Preparation of Electron Transport Layer Liquid ETL-4)
ETL-4 was prepared in the same manner as ETL-3 except that 5% by mass of HCOONa was added to polyethyleneimine.

(Preparation of electron transport layer liquids ETL-5 to ETL-9)
ETL-5 to ETL-9 were prepared in the same manner as ETL-4, except that the type of metal compound added to the electron transport layer solution was changed as shown in Table 1 below.

(Preparation of hole transport layer solution)
(Preparation of hole transport layer solution HTL-1)
A solution obtained by diluting PEDOT-PSS (CLEVIOS (registered trademark) PVP AI 4083, manufactured by Helios Co., Ltd., conductivity 1 × 10 ⁻³ S / cm) composed of a conductive polymer and a polyanion with an equal amount of isopropanol for 1 hour. Stir to prepare HTL-1.

(Preparation of hole transport layer solution HTL-2)
HTL-2 was prepared in the same manner as HTL-1, except that 1% by mass of UV curable silane coupling agent Threebond 3101 (manufactured by ThreeBond Co., Ltd., UV curable) was added to PEDOT: PPS.

(Preparation of hole transport layer liquid HTL-3)
HTL-3 was prepared in the same manner as HTL-1, except that 5 mg of trimethylolpropane triglycidyl ether (TMPTGE) and 5 mg of triethylenetetramine (TETA) were added to PEDOT: PSS.

(Preparation of hole transport layer solution HTL-4)
HTL-4 was prepared in the same manner as HTL-3 except that 5% by mass of TiO ₂ fine particles (TiO ₂ nanopowder manufactured by TECNAN, product number: TECNANPOW-TiO ₂ ) was added to PEDOT: PSS.

(Preparation of hole transport layer solution HTL-5)
HTL-5 was prepared in the same manner as HTL-4 except that the metal compound added to the hole transport layer solution was changed to ₅ % by mass of Nb ₂ O ₅ .

(Preparation of hole transport layer solution HTL-6)
HTL-6 was prepared in the same manner as HTL-5 except that the polymerization agent added to the hole transport layer solution was changed to 1% by weight of Threebond 3101 with respect to PEDOT: PPS.

(Preparation of hole transport layer solutions HTL-7 to HTL-8)
HTL-7 to HTL-8 were prepared in the same manner as HTL-4, except that the metal compound added to the hole transport layer solution was changed as shown in Table 2 below.

(Preparation of hole transport layer solution HTL-9)
PTLOT: HTL-9 was prepared in the same manner as HTL-1, except that 5% by mass of MoO ₃ was added to PPS.

[Measurement of work function]
A sample coated on an ITO substrate with a thickness of about 5 nm for the electron transport layer and about 100 nm for the hole transport layer is prepared, heat treated at 150 ° C. for 10 minutes, and then used for ultraviolet photoelectron spectroscopy (UPS). The work function was measured according to the work function measurement method.

[Production of Reverse Layer Configuration Type Photoelectric Conversion Element SC-101]
A first indium tin oxide (ITO) transparent conductive film deposited on a glass substrate with a thickness of 150 nm (sheet resistance 12 Ω / □) is patterned to a width of 10 mm using a normal photolithography technique and wet etching. The electrode was formed. The patterned first electrode was washed in the order of ultrasonic cleaning with a surfactant and ultrapure water, followed by ultrasonic cleaning with ultrapure water, dried by nitrogen blowing, and finally subjected to ultraviolet ozone cleaning. After this, the substrate was brought into the glove box and operated under a nitrogen atmosphere.

  On this 1st electrode, the electron carrying layer liquid ETL-1 was apply | coated and dried using the blade coater so that the dry film thickness might be set to about 5 nm. Thereafter, heat treatment was performed on a hot plate at 120 ° C. for 1 minute to form an electron transport layer.

  Next, a solution obtained by mixing 0.6 mass% of PCPDTBT, which is a p-type organic semiconductor material, and 1.2 mass% of PC71BM, which is an n-type organic semiconductor material, with o-dichlorobenzene at a mass ratio of 1.2 mass%. Prepare and stir (60 minutes) while heating to 100 ° C. in an oven to dissolve PCPDTBT and PC71BM, and then apply a blade coater so that the dry film thickness is about 100 nm while filtering through a 0.20 μm filter. And then dried at 80 ° C. for 2 minutes to form a photoelectric conversion layer.

  Subsequently, as a hole transport layer, HTL-1 was applied and dried using a blade coater so that the dry film thickness was about 100 nm. Then, it heated at 150 degreeC for 10 minute (s) on the hotplate, and the positive hole transport layer was formed.

Next, the element was set so that the shadow mask with a width of 10 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 1 × 10 ⁻³ Pa or less. A second electrode was formed by stacking 200 nm. The obtained laminate was moved to a nitrogen chamber and sandwiched between ^two relief printing transparent barrier films GX (water vapor transmission rate 0.05 g / m ² / d), and UV curable resin (Nagase ChemteX Corporation). Manufactured, manufactured by UV RESIN XNR5570-B1) and then taken out into the atmosphere to obtain an organic photoelectric conversion element SC-101 having a light receiving portion of about 10 × 10 mm size.

[Production of Photoelectric Conversion Element SC-102]
In production of the organic photoelectric conversion element SC-101, an organic photoelectric conversion element SC-102 was obtained in the same manner as SC-101 except that the electron transport layer liquid was changed to ETL-2.

[Production of Photoelectric Conversion Element SC-103]
In the production of the organic photoelectric conversion element SC-101, the hole transport layer solution was changed to HTL-2, and the same procedure as SC-101 was performed except that the hole transport layer was polymerized by irradiation with a UV lamp for 1 minute. Organic photoelectric conversion element SC-103 was obtained.

[Production of Photoelectric Conversion Elements SC-104 to 105]
In the production of the organic photoelectric conversion element SC-101, an organic photoelectric conversion element SC-101 was prepared in the same manner as SC-101 except that the combination of the electron transport layer liquid and the hole transport layer liquid was changed as shown in Table 3 below. 104-105 were obtained.

[Production of Photoelectric Conversion Element SC-106]
In the production of the organic photoelectric conversion element SC-103, the hole transport layer solution was changed to HTL-6, and the hole transport layer was polymerized by irradiating with a UV lamp for 1 minute. Organic photoelectric conversion element SC-106 was obtained.

[Production of Photoelectric Conversion Elements SC-107 to 110]
In the production of the organic photoelectric conversion element SC-101, an organic photoelectric conversion element SC-101 was prepared in the same manner as SC-101 except that the combination of the electron transport layer liquid and the hole transport layer liquid was changed as shown in Table 3 below. 107-110 were obtained.

[Evaluation of organic photoelectric conversion elements]
(Evaluation of photoelectric conversion efficiency)
The organic photoelectric conversion device manufactured by the above method is irradiated with light of 100 mW / cm ² of solar simulator (AM1.5G filter), and a mask having an effective area of 4.0 mm ² is overlaid on the light receiving portion, and short-circuited. The current density Jsc (mA / cm ² ), the open circuit voltage Voc (V), and the fill factor (fill factor) FF were respectively measured for the four light receiving portions formed on the same element, and the average value, maximum value, and minimum value were measured. The difference was calculated. Further, the energy conversion efficiency η (%) was obtained from Jsc, Voc, and FF according to the following formula 1.

[Formula 1]
η (%) = Jsc (mA / cm ² ) × Voc (V) × FF
The evaluation results are shown in Table 1 below. It shows that energy conversion efficiency (photoelectric conversion efficiency) is so favorable that the number of an average value is large. In addition, the smaller the difference between the maximum value and the minimum value, the more stable conversion efficiency is obtained.

(Durability evaluation of photoelectric conversion efficiency)
The organic photoelectric conversion element for which the photoelectric conversion efficiency was evaluated was heated to 80 ° C. with a resistor connected between the anode and the cathode, and the light of a solar simulator (AM1.5G) was 10 times 1000 mW / cm ² . Exposure continued for 100 hours at irradiation intensity. Thereafter, the organic photoelectric conversion element was cooled to room temperature, and the photoelectric conversion efficiency η (%) was determined for each of the four light receiving portions formed on the same element as described above. The relative efficiency reduction of the conversion efficiency was calculated according to the following formula 2.

[Formula 2]
Reduction in relative efficiency of conversion efficiency (%) = (1−conversion efficiency after exposure / conversion efficiency before exposure) × 100
The evaluation results are shown in Table 3 below. It shows that durability of energy conversion efficiency (durability of photoelectric conversion efficiency) is so favorable that the number of an average value is small.

  With the configuration of the present invention, high durability was obtained at the same time as high conversion efficiency.

[Preparation of normal layer type photoelectric conversion element SC-201]
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate with a thickness of 110 nm (sheet resistance 13 Ω / □) is patterned to a width of 10 mm using ordinary photolithography technology and hydrochloric acid etching, and transparent An electrode was formed.

  The patterned transparent electrode was washed in the order of ultrasonic cleaning with a surfactant and ultrapure water, followed by ultrasonic cleaning with ultrapure water, dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

  Next, as a hole transport layer, HTL-1 was applied and dried using a blade coater so that the dry film thickness was about 50 nm. Then, it heat-processed for 10 minutes with a 150 degreeC hotplate, and formed the positive hole transport layer.

  After this, the substrate was brought into the glove box and operated under a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere.

  Next, a solution obtained by mixing PCDTBT, which is a p-type organic semiconductor material, with 0.6 mass% and PC71BM, which is an n-type organic semiconductor material, with 1.2 mass% in o-dichlorobenzene. Prepare and stir while heating to 100 ° C in an oven (60 minutes) to dissolve PCDTBT and PC71BM, then filter through a 0.20 µm filter, spin coat at 700 rpm for 60 seconds, then 2000 rpm for 2 seconds And a photoelectric conversion layer having a thickness of 100 nm was obtained. Thereafter, an annealing treatment was performed at 120 ° C. for 5 minutes to form a photoelectric conversion layer.

Next, the substrate on which the photoelectric conversion layer was formed was placed in a vacuum evaporation apparatus. Then, the element was set so that the shadow mask with a width of 10 mm was orthogonal to the transparent electrode, and the inside of the vacuum vapor deposition machine was depressurized to 10 ⁻³ Pa or less, and then 10 nm of bathocuproine (BCP) was deposited to form an electron transport layer. Thereafter, Al was evaporated to 80 nm to form a second electrode. The vapor deposition rate was 2 nm / second.

  The obtained organic photoelectric conversion element was sealed with an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then taken out into the atmosphere. An organic photoelectric conversion element SC-201 having a size of 10 mm square was obtained.

[Production of Photoelectric Conversion Elements SC-202 and 203]
In the production of the organic photoelectric conversion element SC-201, organic photoelectric conversion elements SC-202 and 203 were obtained in the same manner as SC-201 except that the combination of the hole transport layer liquids was changed as shown in Table 4 below. It was.

[Evaluation of organic photoelectric conversion elements]
Evaluation similar to that of SC-101 was performed, and the results are shown in Table 4.

  With the configuration of the present invention, high durability was obtained at the same time as high conversion efficiency.

DESCRIPTION OF SYMBOLS 10 Bulk heterojunction type organic photoelectric conversion element 11 Substrate 12 Transparent electrode 13 Counter electrode 14 Photoelectric conversion layer 14 '1st photoelectric conversion layer 15 Charge recombination layer 16 2nd photoelectric conversion layer 17 Hole transport layer 18 Electron transport layer 18

Claims (8)

In the organic photoelectric conversion element having a photoelectric conversion layer and at least one of a hole transport layer or an electron transport layer between the first electrode and the second electrode, at least one of the hole transport layer or the electron transport layer is An organic photoelectric conversion element comprising an organic compound polymerized in the presence of a metal compound. The organic photoelectric conversion element according to claim 1, wherein the metal compound is a metal salt or a metal oxide. The organic photoelectric conversion device according to claim 1, wherein in the polymerization treatment, the treatment method is thermal polymerization. 4. The organic photoelectric conversion device according to claim 1, wherein the metal oxide contained in the hole transport layer is a metal salt or metal oxide of V or Mo. 5. 4. The organic photoelectric conversion device according to claim 1, wherein the metal salt contained in the electron transport layer is a metal salt of Cs and Li. 5. The hole transport layer is a layer containing a metal oxide, the electron transport layer is a layer containing a metal salt, and both layers each contain a polymerized organic compound. The organic photoelectric conversion device according to any one of claims 1 to 5, wherein The organic solar cell comprising the organic photoelectric conversion element according to any one of claims 1 to 6, wherein the first electrode is a cathode and the second electrode is an anode. It is a manufacturing method of the organic photoelectric conversion element which manufactures the organic photoelectric conversion element of any one of Claims 1-6, Comprising: It superposes | polymerizes in presence of the compound which has a metal compound and a reactive group. The manufacturing method of the organic photoelectric conversion element made into.

Images