JP2013077760A - Organic photoelectric conversion element and solar cell using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element which is excellent in durability and is capable of exhibiting sufficient photoelectric conversion efficiency.SOLUTION: The organic photoelectric conversion element of the present invention includes a first electrode, a second electrode, a photoelectric conversion layer existing between the first electrode and the second electrode and containing an n-type organic semiconductor and a p-type organic semiconductor, and a hole transport layer existing between the first electrode or the second electrode and the photoelectric conversion layer. The organic photoelectric conversion element is characterized in that at least one of the photoelectric conversion layer and the hole transport layer contains polyalkyleneimine.

Description

  The present invention relates to an organic photoelectric conversion element and a solar cell using the same.

  In recent years, in order to cope with global warming, reduction of carbon dioxide emissions has been strongly desired. In addition, fossil fuels such as oil, coal, and natural gas are expected to be depleted in the near future, and there is an urgent need to secure an earth-friendly energy resource to replace them. Therefore, development of power generation technology using sunlight, wind power, geothermal heat, nuclear power, and the like has been actively performed, and solar power generation is particularly attracting attention because of its high safety.

  In solar power generation, light energy is directly converted into electric power using a photoelectric conversion element utilizing the photovoltaic effect. Generally, a photoelectric conversion element has a structure in which a photoelectric conversion layer (light absorption layer) is sandwiched between a pair of electrodes, and light energy is converted into electric energy in the photoelectric conversion layer. The photoelectric conversion element is a silicon-based photoelectric conversion element using single-crystal / polycrystalline / amorphous Si, GaAs, CIGS (copper (Cu), indium (In), depending on the material used for the photoelectric conversion layer and the form of the element. Compound-based photoelectric conversion elements using a compound semiconductor such as gallium (Ga) and selenium (Se)), dye-sensitized photoelectric conversion elements (Gretzel cells), and the like have been proposed and put to practical use.

  However, the power generation cost when these solar cells are used is still higher than the cost when generating and transmitting power using fossil fuels, which hinders the spread of solar power generation. In addition, since heavy glass must be used for the substrate, reinforcement work is required when it is installed on a roof or the like, which has also contributed to a rise in power generation costs.

  As a technique for reducing power generation costs in solar power generation, a mixture of an electron-donating organic compound (p-type organic semiconductor) and an electron-accepting organic compound (n-type organic semiconductor) between a transparent electrode and a counter electrode A bulk heterojunction type photoelectric conversion element is proposed (see, for example, Non-Patent Document 1).

  Bulk heterojunction organic photoelectric conversion elements are lightweight and flexible, and are expected to be applied to various products. In addition, since the structure is relatively simple and a photoelectric conversion layer can be formed by applying a p-type organic semiconductor and an n-type organic semiconductor, it is suitable for mass production and contributes to the early diffusion of solar cells due to cost reduction. It is thought to do. More specifically, in a bulk heterojunction organic photoelectric conversion element, a metal layer or a metal oxide layer constituting electrodes (anode and cathode) can be formed by a vapor deposition method, but other layers are coated. It can be formed using a process. Therefore, it is expected that the production of the bulk heterojunction photoelectric conversion element can be performed at high speed and at low cost, and it is considered that there is a possibility that the above-described problem of power generation cost can be solved. Furthermore, unlike the manufacture of conventional silicon-based photoelectric conversion elements, compound-based photoelectric conversion elements, dye-sensitized photoelectric conversion elements, etc., it does not necessarily involve a manufacturing process at a temperature higher than 160 ° C. It is expected that it can be formed on a lightweight plastic substrate.

  However, it cannot be said that the organic photoelectric conversion element has sufficient photoelectric conversion efficiency and durability against heat and light compared to other types of photoelectric conversion elements.

  For example, an organic photoelectric conversion element has a problem that it is easily affected by oxygen and moisture, as in a general organic electronic device (for example, an organic thin film transistor (OTFT) or an organic light emitting diode (OLED)). If oxygen or moisture enters the element, the element deteriorates and the lifetime of the element is shortened. Therefore, it is necessary to prevent such penetration by using a barrier member (for example, a barrier film or a glass plate). .

However, even when sealed with a barrier member, there is inevitably present in the element a small amount of moisture mixed in and remaining as it is, or a small amount of moisture that permeates the barrier member. When continuous light irradiation is performed in such a state where a small amount of moisture exists, an ionic substance or the like in the element diffuses, or a bulk heterojunction layer (formed by a p-type semiconductor material and an n-type semiconductor material) When the morphology of the photoelectric conversion layer) is changed, the short circuit current density (J _SC ) is attenuated, and the lifetime of the device is remarkably shortened.

  In order to cope with these problems, for example, for the purpose of suppressing the diffusion of an anionic component of PEDOT: PSS (poly (3,4-ethylenedithiophene): poly (styrenesulfonate)) used as a hole transporting material, NaOH is used for NaOH. A technique for improving the stability during light irradiation by neutralization has been proposed (for example, Non-Patent Document 2). In addition, a technique has been proposed in which a crosslinkable substituent is introduced into a side chain end of a semiconductor material and the film is cured by cross-linking between molecules to suppress a change in morphology (for example, Non-Patent Document 3). And 4).

A. Heeger et al. , Nature Mat. , Vol. 6 (2007), p497 J. et al. Phys. Chem. C 2011, 115, 13502-13510 Macromolecules, Vol. 42, no. 5, 2009, 1610-1618 J. et al. AM. CHEM. SOC. 2010, 132, 4887-4893

  However, as a result of examinations by the present inventors, it has been found that sufficient durability or photoelectric conversion efficiency cannot be obtained even with the technique described in the above-mentioned document. That is, according to the technique described in Non-Patent Document 2, the work function fluctuates due to neutralization of PSS, and the salt component generated during neutralization remains in the device, so that sufficient durability and photoelectric conversion are achieved. It turns out that efficiency cannot be demonstrated. Further, in the techniques described in Non-Patent Documents 3 and 4, since it is necessary to heat to a high temperature from the outside in order to advance the crosslinking reaction, the morphology becomes coarse and the desired photoelectric conversion efficiency cannot be obtained. I understood that.

  This invention is made | formed in view of the said subject, and it aims at providing the photoelectric conversion element which is excellent in durability and can exhibit sufficient photoelectric conversion efficiency.

  The present inventors have conducted intensive research to solve the above-mentioned problems, and as a result, polyalkyleneimine is added to at least one of the photoelectric conversion layer and the hole transport layer, thereby achieving excellent durability and sufficient photoelectricity. Knowing that the conversion efficiency is exhibited, the present invention has been completed.

  That is, the present invention includes a first electrode; a second electrode; a photoelectric conversion layer including an n-type organic semiconductor and a p-type organic semiconductor that exists between the first electrode and the second electrode; In the organic photoelectric conversion element having the hole transport layer present between the electrode or the second electrode and the photoelectric conversion layer, at least one of the photoelectric conversion layer and the hole transport layer contains a polyalkyleneimine It is characterized by.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the organic photoelectric conversion element which is excellent in durability and can exhibit sufficient photoelectric conversion efficiency.

1 is a schematic cross-sectional view schematically illustrating an organic photoelectric conversion element according to an embodiment of the present invention. It is the cross-sectional schematic which represented typically the organic photoelectric conversion element based on other one Embodiment of this invention. It is the cross-sectional schematic which represented typically the organic photoelectric conversion element provided with the tandem-type photoelectric conversion layer based on other one Embodiment of this invention.

  The present invention relates to a first electrode; a second electrode; a photoelectric conversion layer including an n-type organic semiconductor and a p-type organic semiconductor, which is present between the first electrode and the second electrode; A point in which polyalkyleneimine is added to at least one of the photoelectric conversion layer and the hole transport layer in an organic photoelectric conversion element having a hole transport layer present between the second electrode and the photoelectric conversion layer. It has the characteristics. Thus, although the mechanism by which the effect of improving the durability of the device is obtained by adding alkyleneimine to at least one of the photoelectric conversion layer and the hole transport layer is not clear, the present inventors have the following. I guess so.

  That is, in the organic photoelectric conversion element, various ionic components (for example, an anion component derived from PSS of PEDOT: PSS, a component generated by migration of Ag which is an electrode material, and a catalyst derived from the catalyst used in the synthesis of the polymer material). It is considered that the deterioration of the element is caused by these ionic components that move between the electrodes during light irradiation (during power generation). In contrast, in the present invention, polyalkyleneimine is added to the photoelectric conversion layer and / or the hole transport layer. Since polyalkyleneimine has a function of capturing an ionic component, it is presumed that the migration of the ionic component during light irradiation (power generation) can be prevented and deterioration of the element can be suppressed.

  Furthermore, when polyalkyleneimine is added to the photoelectric conversion layer, the effect of significantly improving the photoelectric conversion efficiency can be obtained as shown in Examples described later. The improvement in the photoelectric conversion efficiency is presumed to be due to the favorable formation of the morphology of the photoelectric conversion layer due to the presence of the polyalkyleneimine.

  Hereinafter, the organic photoelectric conversion element of the present invention will be described with reference to the accompanying drawings. However, the technical scope of the present invention should be determined by the description of the scope of claims, and is not limited only to the following embodiments. . In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  FIG. 1 is a schematic cross-sectional view schematically showing an organic photoelectric conversion element according to an embodiment of the present invention. Specifically, the organic photoelectric conversion element 10 of FIG. 1 has a configuration in which an anode 11, a hole transport layer 26, a photoelectric conversion layer 14, an electron transport layer 27, and a cathode 12 are laminated in this order on a substrate 25. Have

  When the organic photoelectric conversion element 10 shown in FIG. 1 is operated, light is irradiated from the substrate 25 side. In the present embodiment, the anode 11 is made of a transparent electrode material (for example, ITO) so that the irradiated light reaches the photoelectric conversion layer 14. The light irradiated from the substrate 25 side reaches the photoelectric conversion layer 14 through the transparent anode 11 and the hole transport layer 26.

  In FIG. 1, light incident from the anode 11 through the substrate 25 is absorbed by the electron acceptor or electron donor in the photoelectric conversion layer 14, and electrons move from the electron donor to the electron acceptor. Pair (charge separation state) is formed.

  In the case where the generated electric charges have different internal electric fields, for example, when the work functions of the anode 11 and the cathode 12 are different, the electrons pass between the electron acceptors and the holes pass between the electron donors due to the potential difference between the anode 11 and the cathode 12. Each is carried to a different electrode and the photocurrent is detected.

  The hole transport layer 26 is formed of a material having a high hole mobility, and has a function of efficiently transporting holes generated at the pn junction interface of the photoelectric conversion layer 14 to the anode 11. . On the other hand, the electron transport layer 27 is made of a material having high electron mobility, and has a function of efficiently transporting electrons generated at the pn junction interface of the photoelectric conversion layer 14 to the cathode 12.

  FIG. 2 is a schematic cross-sectional view schematically showing an organic photoelectric conversion device according to another embodiment of the present invention. The organic photoelectric conversion element 20 in FIG. 2 has the anode 11 and the cathode 12 disposed at opposite positions as compared with the organic photoelectric conversion element 10 in FIG. 1, and the hole transport layer 26, the electron transport layer 27, and the like. Are different in that they are arranged at the opposite positions. 2 has a configuration in which the cathode 12, the electron transport layer 27, the photoelectric conversion layer 14, the hole transport layer 26, and the anode 11 are laminated on the substrate 25 in this order. ing. With this configuration, electrons generated at the pn junction interface of the photoelectric conversion layer 14 are transported to the cathode 12 through the electron transport layer 27, and holes are transported to the anode 11 through the hole transport layer 26. Transported.

  FIG. 3 is a schematic cross-sectional view schematically illustrating an organic photoelectric conversion element including a tandem (multi-junction type) photoelectric conversion layer according to another embodiment of the present invention. Compared with the organic photoelectric conversion element 10 in FIG. 1, the organic photoelectric conversion element 30 in FIG. 3 replaces the photoelectric conversion layer 14 with a first photoelectric conversion layer 14 a, a second photoelectric conversion layer 14 b, and these The difference is that a stacked body with a charge recombination layer 38 interposed between two photoelectric conversion layers is disposed. In the tandem organic photoelectric conversion element 30 shown in FIG. 3, photoelectric conversion materials (p-type organic semiconductor and n-type organic semiconductor) having different absorption wavelengths are used for the first photoelectric conversion layer 14a and the second photoelectric conversion layer 14b, respectively. By using this, light in a wider wavelength range can be efficiently converted into electricity. Hereinafter, each component of the organic photoelectric conversion element according to the present invention will be described in detail.

[electrode]
The organic photoelectric conversion element of this embodiment essentially includes a first electrode and a second electrode. The first electrode and the second electrode each function as an anode or a cathode. In the present specification, “first” and “second” are terms for distinguishing functions as an anode or a cathode. Therefore, the first electrode may function as an anode and the second electrode may function as a cathode. Conversely, the first electrode may function as a cathode and the second electrode may function as an anode. is there. Carriers (holes / electrons) generated in the photoelectric conversion layer 14 move between the electrodes, and the holes reach the anode 12 and the electrons reach the cathode 16. In the present invention, an electrode through which holes mainly flow is called an anode, and an electrode through which electrons mainly flow is called a cathode. Moreover, when taking a tandem structure, a tandem structure can be achieved by using a charge recombination layer (intermediate electrode). Furthermore, from the functional aspect of whether or not the electrode has translucency, the translucent electrode is sometimes referred to as a transparent electrode, and the non-translucent electrode is sometimes referred to as a counter electrode. In the case of the form of FIG. 1, the anode is usually a transparent electrode having a light transmitting property, and the cathode is a counter electrode having no light transmitting property.

  The material used for the electrode of this embodiment is not particularly limited as long as it is driven as a photoelectric conversion element, and an electrode material that can be used in this technical field can be appropriately employed. Among them, the anode is preferably composed of a material having a relatively large work function compared to the cathode, and conversely, the cathode is preferably composed of a material having a relatively small work function compared to the anode. . Note that in the case where a charge transport layer (a hole transport layer or an electron transport layer) is present, it functions sufficiently as a photoelectric conversion element even in a form other than the above.

  In the organic photoelectric conversion element 10 shown in FIG. 1 described above, the anode 11 has a relatively large work function and is transparent (preferably has a transmittance of 80% or more for visible light of 380 to 800 nm). It is preferable that it is comprised from a material. On the other hand, the cathode 12 has a relatively small work function (for example, 4 eV or less), and can usually be composed of an electrode material having low translucency.

In such an organic photoelectric conversion element 10 shown in FIG. 1, examples of electrode materials used for the anode (transparent electrode) include metals such as gold, silver, and platinum; indium tin oxide (ITO), SnO _2. And transparent conductive metal oxides such as ZnO; carbon materials such as metal nanowires and carbon nanotubes. It is also possible to use a conductive polymer as the anode electrode material. Examples of the conductive polymer that can be used for the anode include PEDOT: PSS, polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polyphenyl. Examples include acetylene, polydiacetylene, polynaphthalene, and derivatives thereof. These electrode materials may be used alone or as a mixture of two or more materials. Also, the shape of these materials is not particularly limited, and can be used in the form of nanoparticles, nanowires, ultrathin films and the like. Furthermore, it is also possible to constitute an electrode by laminating two or more layers made of each material.

On the other hand, in the organic photoelectric conversion element of FIG. 1, an alloy, an electron conductive compound, and a mixture thereof can be used as an electrode material used for the cathode (counter electrode). Specifically, sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, indium, Examples include lithium / aluminum mixtures and rare earth metals. Of these, a mixture of a first metal having a low work function and a second metal, which is a metal having a larger work function and more stable than the first metal, from the viewpoint of electron extraction performance and durability against oxidation, etc. For example, it is preferable to use a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum which is a stable metal, or the like. In addition, it is also preferable to use a metal among these materials, so that light that is incident from the first electrode side and transmitted without being absorbed by the photoelectric conversion layer is reflected by the second electrode and is regenerated for photoelectric conversion. The photoelectric conversion efficiency can be improved. Also, the shape of these materials is not particularly limited, and can be used in the form of nanoparticles, nanowires, ultrathin films and the like. Furthermore, it is also possible to constitute an electrode by laminating two or more layers made of each material.

  In the organic photoelectric conversion element shown in FIG. 2, the cathode 12 is located on the substrate 25 side where light enters, and the anode 11 is located on the opposite side. Therefore, the anode 11 shown in FIG. 2 is preferably composed of an electrode material having a relatively large work function and usually low translucency. On the other hand, the cathode 12 has a relatively small work function and is made of a transparent electrode material.

In the organic photoelectric conversion element of FIG. 2, examples of the electrode material used for the cathode (transparent electrode) include metals such as gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, indium, tin, and zinc, Metal compounds, and alloys (specifically, indium tin oxide (ITO), SnO ₂ , ZnO, IDIXO (In ₂ O ₃ —ZnO)); carbon such as carbon nanoparticles, carbon nanowires, and carbon nanostructures Materials; These electrode materials may be used alone or as a mixture of two or more materials. Also, the shape of these materials is not particularly limited, and can be used in the form of nanoparticles, nanowires, ultrathin films and the like. Furthermore, it is also possible to constitute an electrode by laminating two or more layers made of each material. Among these, it is preferable to use carbon nanowires because a transparent and highly conductive cathode can be formed by a coating method. When using a metal-based material, on the side facing the anode (counter electrode), for example, gold, silver, copper, iron, nickel, chromium, aluminum, or an alloy thereof (aluminum alloy), metal compound ( After preparing an auxiliary electrode (also referred to as a grid electrode or a bus line electrode) using a silver compound) or the like, the conductive polymer exemplified as the anode (transparent electrode) material of the organic photoelectric conversion element in FIG. By providing this film, a cathode (transparent electrode) can be obtained. By providing the auxiliary electrode in this way, it is possible to suppress the reduction of the fill factor (FF) that occurs when the element has a large area.

  The shape of the auxiliary electrode is not particularly limited, but for example, the conductive portion has a stripe shape, a mesh shape, or a random mesh shape. There are no particular limitations on the method of forming the stripe-shaped or mesh-shaped auxiliary electrode with the conductive portion, and a conventionally known method can be used. For example, a metal layer can be formed on the entire surface of the substrate and can be formed by a known photolithography method. Specifically, a method of forming a conductor layer on the entire surface of the substrate using one or more physical or chemical forming methods such as vapor deposition, sputtering, plating, etc., or a metal foil on the substrate with an adhesive After the lamination, it can be processed into a desired stripe shape or mesh shape by a method of etching using a known photolithography method. As another method, a method of printing an ink containing metal fine particles in a desired shape by various printing methods such as screen printing, flexographic printing, gravure printing, and an ink jet method, and various printing methods similar to plating catalyst ink As another method, a method of applying a silver salt photographic technique can be used after coating in a desired shape. Among these methods, the method of printing ink containing metal fine particles in a desired shape by various printing methods can be manufactured in a simple process, so that it is possible to reduce the entrainment of foreign matters that may cause leakage at the time of manufacture. Since the ink is used only at the portions, the liquid loss is small, which is most preferable.

  On the other hand, in the organic photoelectric conversion element of FIG. 2, examples of the electrode material used for the anode (counter electrode) include silver, nickel, molybdenum, gold, platinum, tungsten, and copper.

  The sheet resistance of the first electrode and the second electrode is not particularly limited, but is preferably several hundred Ω / □ or less, more preferably 50Ω / □ or less, and further preferably 15Ω / □ or less. Also, the thickness of each electrode is not particularly limited and varies depending on the material, but is usually 10 to 1000 nm, preferably 100 to 200 nm, and can be appropriately set by those skilled in the art from the viewpoint of light transmittance or resistance. .

  Further, the sheet resistance when the auxiliary electrode is provided is preferably 10Ω / □ or less, and more preferably 0.01 to 8Ω / □. In this case, the sheet resistance is determined by the shape (line width, height, pitch, shape) of the auxiliary electrode, and even if a material having higher resistance than the auxiliary electrode is used, the resistance of the window portion is hardly affected.

[Photoelectric conversion layer]
(N-type organic semiconductor and p-type organic semiconductor)
The photoelectric conversion layer has a function of converting light energy into electric energy using the photovoltaic effect. 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 used for the photoelectric conversion layer of this embodiment is not particularly limited as long as it is a donor (electron donating) organic compound, and materials that can be used in this technical field can be appropriately adopted. Among such compounds, as the condensed polycyclic aromatic low molecular weight compound, for example, anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, Compounds such as circumanthracene, bisanthene, bisanthene, heptazethrene, pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, Examples include bisethylenedithiotetrathiafulvalene (BEDTTTF) -perchloric acid complex, and derivatives and precursors thereof.

  Examples of the derivative having the above-mentioned condensed polycycle include WO 03/16599 pamphlet, WO 03/28125 pamphlet, US Pat. No. 6,690,029, JP 2004-107216 A. A pentacene derivative having a substituent described in JP-A No. 2003-136964, a pentacene precursor described in US Patent Application Publication No. 2003/136964, and the like; Amer. Chem. Soc. , Vol127. No. 14.4986, J. MoI. Amer. Chem. Soc. , Vol. 123, p9482; Amer. Chem. Soc. , Vol. 130 (2008), no. 9, acene-based compounds substituted with a trialkylsilylethynyl group described in 2706 and the like.

  As the conjugated polymer, for example, a polythiophene such as poly-3-hexylthiophene (P3HT) and its oligomer, or a polymerizable group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Polythiophene, Nature Material, (2006) vol. 5, p328, a polythiophene-thienothiophene copolymer described in WO2008000664, a polythiophene-diketopyrrolopyrrole copolymer described in WO2008000664, a polythiophene-thiazolothiazole copolymer described in Adv Mater, 2007p4160, Nature Mat. vol. 6 (2007), p497, a polythiophene copolymer such as PCPDTBT, Adv. Mater. , Vol. 19, (2007) p2295 polythiophene-carbazole-benzothiadiazole copolymer (PCDTBT), Macromolecules 2009, 42, p1610-1618 vinyl group-substituted polyhexylthiophene (P3HNT), polypyrrole and its oligomer, polyaniline, Polymer materials such as polyphenylene and oligomers thereof, polyphenylene vinylene and oligomers thereof, polythienylene vinylene and oligomers thereof, σ-conjugated polymers such as polyacetylene, polydiacetylene, polysilane, and polygermane.

  In addition, oligomeric materials instead of polymer materials include thiophene hexamer α-sexual thiophene α, ω-dihexyl-α-sexual thiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3 Oligomers such as -butoxypropyl) -α-sexithiophene can be preferably used.

  Among these compounds, compounds that have high solubility in organic solvents to the extent that solution processing is possible, can form a crystalline thin film after drying, and can achieve high mobility are preferable. More preferably, it is a compound (a compound capable of forming an appropriate phase separation structure) having appropriate compatibility with a fullerene derivative which is an n-type organic semiconductor material described later.

  In addition, when forming an electron transport layer or a hole blocking layer by a solution process on the bulk heterojunction layer, if it can be further applied on the layer once applied, it can be easily laminated, When a layer is further laminated by a solution process on a layer made of a material that usually has good solubility, there is a problem that the layer cannot be laminated because the underlying layer is dissolved. Therefore, a material that can be insolubilized after application by a solution process is preferable.

  Examples of such a material include materials that can be insolubilized by polymerizing and crosslinking the coating film after coating, such as polythiophene having a polymerizable group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Or a material in which soluble substituents react and become insoluble (pigmented) by applying energy such as heat, as described in US Patent Application Publication No. 2003/136964, and Japanese Patent Application Laid-Open No. 2008-16834 Etc.

  On the other hand, the n-type organic semiconductor used for the photoelectric conversion layer of this embodiment is not particularly limited as long as it is an acceptor (electron-accepting) organic compound, and a material that can be used in this technical field may be appropriately adopted. it can. Such compounds include, for example, fullerenes, carbon nanotubes, octaazaporphyrins, and the like perfluoro compounds in which the hydrogen atoms of the p-type organic semiconductor are substituted with fluorine atoms (for example, perfluoropentacene and perfluorophthalocyanine), naphthalene, etc. Examples thereof include aromatic carboxylic acid anhydrides such as tetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, and perylenetetracarboxylic acid diimide, and polymer compounds containing the 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 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 may be used alone or in combination of two or more.

  There is no particular limitation on the junction form of the p-type organic semiconductor and the n-type organic semiconductor in the photoelectric conversion layer of this embodiment, and it may be a planar heterojunction or a bulk heterojunction (bulk heterojunction). Good. 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 is formed by applying a mixture of a p-type organic semiconductor and an n-type organic semiconductor. In this single layer, a domain of the p-type organic semiconductor and a domain of the n-type organic semiconductor are formed. It has a microphase separation structure. Therefore, in a bulk heterojunction, many pn junction interfaces exist throughout the layer as compared to a planar heterojunction. 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.

  The bulk heterojunction layer is formed of a single layer (i layer) in which a normal p-type organic semiconductor material and an n-type organic semiconductor layer are mixed, and the i layer is made of a p-type organic semiconductor. In some cases, it has a three-layer structure (p-i-n structure) sandwiched between a p layer and an n layer made of an n-type organic semiconductor. Such a pin structure has higher rectification of holes and electrons, reduces loss due to recombination of charge-separated holes and electrons, and can achieve higher photoelectric conversion efficiency. .

  In the present invention, the mixing ratio of the p-type organic semiconductor and the n-type organic semiconductor contained in the photoelectric conversion layer is preferably in the range of 2: 8 to 8: 2, more preferably 4: 6 to 6: 4. Range.

(Polyalkyleneimine)
The organic photoelectric conversion element of this embodiment is characterized in that polyalkyleneimine is essential in at least one of the photoelectric conversion layer and the hole transport layer described later. Hereinafter, an embodiment in which a polyalkyleneimine is contained in the photoelectric conversion layer will be described.

  In the present invention, the polyalkyleneimine means a linear or branched polymer having an aminoalkylene group as a repeating unit. In this specification, oligomers such as dimers and trimers are also included in the polyalkyleneimine. As an example of the polyalkyleneimine used in this embodiment, polyethyleneimine which is a branched polymer having an aminoethylene group as a repeating unit is represented by the following chemical formula 1.

The polyethyleneimine represented by the chemical formula 1 includes a primary amino group (NH ₂ —CH ₂ CH ₂ —), a secondary amino group (NH— (CH ₂ CH ₂ —) ₂ ), a tertiary amino group (N - including _{3) - (CH 2 CH 2} ). Of these, the primary amino group constitutes the end of the chain, and the tertiary amino group constitutes the branching point of the chain.

The polyalkyleneimine of this embodiment is not particularly limited as long as it is a polymer having an aminoalkylene group as a repeating unit as described above. Examples of the alkylene group contained in the aminoalkylene group include a methylene group (—CH ₂ —), an ethylene group (—CH ₂ CH ₂ —), a trimethylene group (—CH ₂ CH ₂ CH ₂ —), a propylene group ( —CH (CH ₃ ) CH ₂ —), tetramethylene group (—CH ₂ CH ₂ CH ₂ CH ₂ —), 1,2-dimethylethylene group (—CH (CH ₃ ) CH (CH ₃ ) —), etc. Can be mentioned. Among these, ethylene group, trimethylene group, and propylene group are preferable, and ethylene group, trimethylene group, and propylene group are more preferable from the viewpoint of easy synthesis and availability or compatibility with the coating solution. The terminal structure is not particularly limited, but is usually a primary amino group (—NH ₂ ) or an alkyl group (eg, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, etc.) It can be.

  The polyalkyleneimine of this form may be linear (that is, not containing a tertiary amino group) or branched, but from the viewpoint of improving reactivity, branched polyalkyleneimine It is preferable that Further, the branched structure when the polyalkyleneimine is branched is not particularly limited, and may be a network structure or a dendrimer structure. The content ratio of the primary amino group, secondary amino group, and tertiary amino group in the case of the branched polyalkyleneimine is not particularly limited, but the content ratio of the primary amino group is From the viewpoint of improving the reactivity by increasing the cation density, it is preferably 5 to 60 mol%, more preferably 20 to 50%, more preferably 30 to 45% with respect to 100 mol% of all amino groups. More preferably. Further, from the viewpoint of satisfactorily forming a polymer network, the content ratio of secondary amino groups is preferably 25 to 55 mol%, and preferably 30 to 45% with respect to 100 mol% of all amino groups. More preferably, the content ratio of the tertiary amino group is preferably 15 to 45 mol%, more preferably 15 to 35%. In addition, in this specification, the value calculated | required by the method as described in the below-mentioned Example is employ | adopted for the content rate of the primary amino group of a polyalkylene imine, a secondary amino group, and a tertiary amino group.

  Amine number of polyalkyleneimine (indicating the total amount of primary amino group, secondary amino group, and tertiary amino group, mg number of potassium hydroxide equivalent to hydrochloric acid required to neutralize 1 g of sample) Is usually 2 to 40 mmol / g, preferably 10 to 30 mmol / g. When the amine value is 2 mmol / g or more, reactivity with the diffusing substance is obtained, and when it is 40 mmol / g or less, an increase in the viscosity of the coating solution can be suppressed. In the present specification, the method for measuring the amine value of polyalkyleneimine is as follows. About 1 g of sample is precisely weighed (sample amount: Sg), 20 ml of toluene is added to dissolve, and 20 ml of isopropyl alcohol and a few drops of bromophenol blue solution are added, and 1/10 N isopropyl alcohol solution (titer: f) is added. Titration and read titration to end point. (Titration: A [ml]) From this titration, the amine value is calculated by the following formula 1.

  The molecular weight of the polyalkyleneimine that can be preferably used in the present invention is not particularly limited as long as the effect of the present invention is exhibited, but is usually 100 to 50,000 in terms of number average molecular weight, preferably 300 to 10,000, Preferably about 500-5000 is preferable. The number average molecular weight can be evaluated by polystyrene conversion from the value measured by GPC (for example, HLC-8220 manufactured by TOSOH).

  The polyalkyleneimine used in this embodiment may be a commercially available product or a product obtained by synthesis. When polyalkyleneimine is prepared by synthesis, it can be synthesized by the method described in JP-B-49-33120. Specifically, polyalkyleneimine can be obtained by reacting alkyleneimine with ethylenediamine, diethylenetriamine, monoethanolamine or the like as a raw material in the presence of an acid catalyst such as hydrochloric acid, sulfuric acid or p-toluenesulfonic acid. Moreover, as a commercial item, for example, linear polyethyleneimine is available from Wako Pure Chemical Industries, Kanto Chemical Co., Ltd., etc. For example, Epomin (registered trademark) SP-003, SP-006, SP-012, SP-018, SP-200, P-1000, etc. manufactured by Nippon Shokubai Co., Ltd. can be used as the branched polyethyleneimine.

  The polyalkyleneimine used in this embodiment is partially modified with a primary amino group or a secondary amino group in order to improve the solubility in a coating solution when forming a photoelectric conversion layer or a hole transport layer. It may be what was done. Specifically, a modified polyalkyleneimine formed by bonding at least one selected from the group consisting of groups represented by the following general formulas 1 to 7 to at least a part of a nitrogen atom can be preferably used.

In the formula, R ^{1 to} R ⁴ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. The polyalkyleneimine modified by the group represented by the general formula 1 can be obtained by reacting the polyalkyleneimine with a corresponding epoxide.

In the formula, each R ⁵ independently represents a linear or branched alkyl group having 1 to 30 carbon atoms. The polyalkyleneimine modified by the group represented by the general formula 2 can be obtained by reacting the polyalkyleneimine with a corresponding isocyanate.

In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 30 carbon atoms. The polyalkyleneimine modified by the group represented by the general formula 3 can be obtained by reacting the polyalkyleneimine with a corresponding aldehyde or ketone.

In formula, R < ⁸ > -R < ¹¹ > represents a hydrogen atom and a C1-C4 linear or branched alkyl group each independently. The polyalkyleneimine modified by the group represented by the general formula 4 can be obtained by reacting the polyalkyleneimine with a corresponding alkene.

In the formula, each R ¹² independently represents a linear or branched alkyl group having 1 to 30 carbon atoms. The polyalkyleneimine modified by the group represented by the general formula 5 can be obtained by reacting the polyalkyleneimine with a corresponding alkyl halide.

In the formula, each R ¹³ independently represents a linear or branched alkyl group having 1 to 30 carbon atoms. The polyalkyleneimine modified by the group represented by the general formula 6 can be obtained by reacting the polyalkyleneimine with a corresponding carboxylic acid or the like.

In the formula, each R ¹⁴ independently represents a linear or branched alkylene group having 1 to 30 carbon atoms, an arylene group, or a heteroarylene group. The polyalkyleneimine modified by the group represented by the general formula 7 can be obtained by reacting the polyalkyleneimine with a corresponding carboxylic acid anhydride or the like.

The modification rate of the modified polyalkyleneimine (ratio of amino groups formed by adding the substituents after modification to the total number of primary amino groups and secondary amino groups before modification) is preferably 10% to 90%. %, More preferably 15% to 70%, and still more preferably 20% to 50%. If the modification rate is 10% or more, sufficient solubility to be dissolved in the coating solution can be ensured. On the other hand, when the modification rate is 90% or less, since the active amino group (primary amino group and secondary amino group) is contained, the effect of the present invention can be exhibited more remarkably. In the present specification, the modification rate can be calculated by ¹³ C-NMR measurement.

  The polyalkyleneimine of this form may be a homopolymer consisting only of aminoalkylene units or a copolymer (heteropolymer) containing two or more aminoalkylene units. Moreover, the copolymer containing other units other than an amino alkylene unit may be sufficient. Other units are not particularly limited as long as the effects of the present invention are not significantly reduced. For example, polyester compound units, acrylic compound units, polyurethane compound units, acrylic urethane compound units, polycarbonate compound units, cellulose compound units, polyvinyl compounds. Examples include acetal compound units and polyvinyl alcohol compound units. In the present invention, the copolymer may be either a random copolymer or a block copolymer, and is preferably a block copolymer. The content ratio of these other units can be selected from the viewpoint of compatibility with the coating solvent and the solute, and is preferably 50 mol% or less with respect to the total number of amino alkylene units of 100 mol%, and 20 mol. % Or less is more preferable.

  In addition, only one type of polyalkyleneimine contained in one photoelectric conversion layer may be used alone, or two or more types may be used in combination. Moreover, 2 or more types of polyalkyleneimines may be contained. Further, when two or more photoelectric conversion layers are included as in the tandem organic photoelectric conversion element of FIG. 3 described above, only one photoelectric conversion layer may contain polyalkyleneimine, or two or more photoelectric conversion layers may be included. The conversion layer may contain polyalkyleneimine. Among these, from the viewpoint of more remarkably exerting the function and effect of the present invention, a form in which polyalkyleneimine is contained in all the photoelectric conversion layers is most preferable. Moreover, in the form in which the polyalkyleneimine is contained in two or more photoelectric conversion layers, the polyalkyleneimines contained in the respective photoelectric conversion layers may be the same as or different from each other.

  Moreover, the film thickness of one photoelectric conversion layer is preferably 50 to 400 nm, more preferably 80 to 300 nm, and particularly preferably 100 to 200 nm. In general, from the viewpoint of absorbing more light, it is preferable that the thickness of the photoelectric conversion layer is larger. However, as the film thickness increases, the extraction efficiency of carriers (holes / electrons) decreases, so the photoelectric conversion efficiency decreases. Tend to.

  In this embodiment, the content of the polyalkyleneimine contained in one photoelectric conversion layer is preferably 0.1 to 10% by mass with respect to 100% by mass of the solid content of the anti-conductivity conversion layer film. More preferably, it is -5 mass%. When the polyalkyleneimine content is 0.1% by mass or more, desired durability and photoelectric conversion efficiency can be obtained. On the other hand, when the content of the polyalkyleneimine is 10% by mass or less, the device efficiency is not lowered, which is preferable.

[substrate]
When light that is photoelectrically converted enters from the substrate side, the substrate is preferably a member that can transmit the light that is photoelectrically converted, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted. Here, “transparent” means that the transmittance is 80% or more with respect to visible light of 380 to 800 nm. As the substrate, for example, a glass substrate, a resin substrate and the like are preferably mentioned, but it is desirable to use a transparent resin film from the viewpoint of light weight 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 these, 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.

  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.

[Hole transport layer]
The organic photoelectric conversion element of this embodiment essentially includes a hole transport layer. The hole transport layer has a function of transporting holes and a property of extremely small ability to transport electrons (for example, 1/10 or less of the mobility of holes). The hole transport layer is provided between the photoelectric conversion layer and the anode and prevents recombination of electrons and holes by blocking the movement of electrons while transporting holes to the anode. Can do. Therefore, in this specification, a positive hole injection layer, an electronic block layer, etc. are also included in the concept of a positive hole transport layer.

  There is no restriction | limiting in particular in the hole transport material used for a hole transport layer, The material which can be used in this technical field can be employ | adopted suitably.

  The conductive polymer preferably used in the present invention is not particularly limited, but preferably comprises a π-conjugated polymer and a polyanion. Such a polymer can be easily produced by subjecting a precursor monomer forming a π-conjugated polymer to chemical oxidative polymerization in the presence of an appropriate oxidizing agent, an oxidation catalyst, and a polyanion described later.

  Examples of the π-conjugated polymer that can be used in the present invention include polythiophenes (including basic polythiophenes, the same applies hereinafter), polypyrroles, polyindoles, polycarbazoles, polyanilines, polyacetylenes, polyfurans, and polyparaffins. A chain conductive polymer of phenylene vinylenes, polyazulenes, polyparaphenylenes, polyparaphenylene sulfides, polyisothianaphthenes, polythiazyl compounds can be used. Of these, polythiophenes and polyanilines are preferable from the viewpoints of conductivity, transparency, stability, and the like. Furthermore, polyethylenedioxythiophenes are preferable.

  The polyanion preferably used in the present invention is not particularly limited, but it is more preferable to have a sulfo group as the anionic group. Specific examples of polyanions include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid ethyl sulfonic acid, polyacrylic acid butyl sulfonic acid, poly-2-acrylamido-2-methylpropane sulfonic acid, polyisoprene sulfone. An acid etc. are mentioned. These homopolymers may be sufficient and 2 or more types of copolymers may be sufficient.

  Moreover, the polyanion which has a fluorine (F) in a compound may be sufficient. Specifically, Nafion (made by Dupont) containing a perfluorosulfonic acid group, Flemion (made by Asahi Glass Co., Ltd.) made of perfluoro vinyl ether containing a carboxylic acid group, and the like can be mentioned.

  As the conductive polymer, known materials and commercially available materials can be preferably used. For example, for example, PEDOT: PSS made by Heraeus Co., Ltd., trade name CLEVIOS-P and the like, containing fluorine-based polyanions (Nafion etc.) described in European Patent No. 1546237, JP-A-2009-1329797, or the like, or Fluorine-based polyanion-added structure as described in JP-A-2006-225658, polythienothiophenes described in European Patent No. 1647566, sulfonated polythiophenes described in JP-A-2010-206146, polyaniline and a doping material thereof, The cyanide compounds described in WO 2006/019270 pamphlet and the like are commercially available as PEDOT-PASS 483095 and 560598 from Aldrich and as the Denatron series from Nagase Chemtex. Polyaniline is also commercially available from Nissan Chemical as the ORMECON series. In the present invention, such an agent can also be preferably used.

  Also, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives Further, stilbene derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, particularly thiophene oligomers, and the like can also be used.

  In addition to these, porphyrin compounds, aromatic tertiary amine compounds, styrylamine compounds, and the like can be used, and among these, aromatic tertiary amine compounds are preferably used. In some cases, the hole transport layer may be formed using an inorganic compound such as p-type-Si, p-type-SiC, nickel oxide, molybdenum oxide, vanadium oxide, or tungsten oxide.

  Furthermore, a polymer material in which a structural unit contained in the above compound is introduced into a polymer chain, or a polymer material having the above compound as the main chain of the polymer can also be used as a hole transport material. JP-A-11-251067, J. Org. Huang et. al. , Applied Physics Letters, 80 (2002), p. A p-type hole transport material as described in 139 can also be used. Furthermore, a hole transport material with high p property doped with impurities can be used. For example, JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004), Appl. Phys. Let. , 98, 073311 (2011), and the like.

  In addition, these hole transport materials may be used individually by 1 type, and may use 2 or more types together. It is also possible to form a hole transport layer by laminating two or more layers made of each material.

  The thickness of the hole transport layer is not particularly limited, but is usually 1 to 2000 nm. From the viewpoint of further improving the leak prevention effect, the thickness is preferably 5 nm or more. Further, from the viewpoint of maintaining high transmittance and low resistance, the thickness is preferably 1000 nm or less, and more preferably 200 nm or less.

In general, the conductivity of the hole transport layer is preferably as high as possible. However, if the conductivity is too high, the ability to prevent electrons from moving may be reduced, and rectification may be reduced. Therefore, the conductivity of the hole transport layer is preferably 10 ⁻⁵ to 1 S / cm, and more preferably 10 ⁻⁴ to 10 ⁻² S / cm.

  The organic photoelectric conversion element of this embodiment is characterized in that polyalkyleneimine is essential in at least one of the photoelectric conversion layer and the hole transport layer described later. Hereinafter, an embodiment in which a polyalkyleneimine is contained in the hole transport layer will be described.

  When the polyalkyleneimine is contained in the hole transporting layer, the same polyalkyleneimine as the polyalkyleneimine in the form in which the above-described photoelectric conversion layer contains the polyalkyleneimine can be used without limitation. Therefore, the detailed description about the specific description of the polyalkyleneimine that can be used in this embodiment is omitted here.

  As for the polyalkyleneimine contained in the hole transport layer, only one kind may be used alone, or two or more kinds may be used in combination. Moreover, 2 or more types of polyalkyleneimines may be contained. Further, when the hole transport layer is a laminate of layers having two or more hole transport functions (or hole injection function, electron blocking function), only one layer contains polyalkyleneimine. The polyalkyleneimine may be contained in two or more layers. Moreover, in the form in which the polyalkyleneimine is contained in two or more layers, the polyalkyleneimine contained in each photoelectric conversion layer may be the same or different from each other.

  In this embodiment, the content of the polyalkyleneimine contained in the hole transport layer is preferably 0.05 to 10% by mass with respect to 100% by mass of the solid content of the hole transport layer material. More preferably, it is -5 mass%, and it is further more preferable that it is 0.5-3 mass%. When the polyalkyleneimine content is 0.05% by mass or more, desired durability and photoelectric conversion efficiency can be obtained. On the other hand, when the content of the polyalkyleneimine is 10% by mass or less, there is no possibility that the initial photoelectric conversion efficiency is remarkably lowered.

  Furthermore, the organic photoelectric conversion element of this embodiment preferably contains a polyalkyleneimine in both the photoelectric conversion layer and the hole transport layer from the viewpoint of further improving the photoelectric conversion efficiency and the durability of the element. In this case, the polyalkyleneimine contained in each of the photoelectric conversion layer and the hole transport layer may be the same or different.

(Electron transport layer)
The organic photoelectric conversion element of this form can contain an electron carrying layer as needed. The electron transport layer has a property of transporting electrons and having a remarkably small ability to transport holes. The electron transport layer is provided between the photoelectric conversion layer and the cathode, and prevents the recombination of electrons and holes by blocking the movement of holes while transporting electrons to the cathode. it can. Therefore, in this specification, an electron injection layer, a hole block layer, an exciton block layer, and the like are also included in the concept of the electron transport layer.

  There is no restriction | limiting in particular in the electron transport material used for an electron carrying layer, The material which can be used in this technical field can be employ | adopted suitably. Examples include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. In addition, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq ₃ ), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) Aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg Metal complexes replaced with Cu, Ca, Sn, Ga, or Pb can also be used as electron transport materials. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. As with the hole transport layer described above, an inorganic semiconductor such as n-type-Si or n-type-SiC, or an inorganic oxide having n-type conductivity (such as titanium oxide or zinc oxide) should be used as an electron transport material. Can do.

  Furthermore, a material species that forms an interface dipole by bonding a dipole material to the electrode and improves charge extraction, such as 3- (2-aminoethyl) aminopropyltrimethoxysilane (AEAP) described in WO2008 / 134492 -TMOS).

  Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

  Specific examples include N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD) and 4,4′-bis [N- (naphthyl)- Aromatic diamine compounds such as N-phenyl-amino] biphenyl (α-NPD) and derivatives thereof, oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene, 4 , 4 ', 4 "-tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. , Triazole derivatives, oxa Zazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. In the polymer material, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and derivatives thereof can be preferably used.

  The thickness of the electron transport layer is not particularly limited, but is usually 1 to 2000 nm. From the viewpoint of further improving the leak prevention effect, the thickness is preferably 5 nm or more. Further, from the viewpoint of maintaining high transmittance and low resistance, the thickness is preferably 1000 nm or less, and more preferably 200 nm or less.

(Charge recombination layer; intermediate electrode)
In a tandem (multi-junction type) organic photoelectric conversion element having two or more photoelectric conversion layers as shown in FIG. 3, a charge recombination layer (intermediate electrode) is disposed between the photoelectric conversion layers.

  The material used for the charge recombination layer (intermediate electrode) is not particularly limited as long as it is a material having both conductivity and translucency. Examples of the electrode material described above include ITO, AZO, FTO, and titanium oxide. Transparent metal oxides, metals such as Ag, Al, and Au, carbon materials such as carbon nanoparticles and carbon nanowires, conductive polymers such as PEDOT: PSS, polyaniline, and the like can be used. These materials may be used alone or in combination of two or more. It is also possible to form a charge recombination layer by laminating two or more layers made of each material. In addition, the hole transport layer and the electron transport layer described above also have a combination that works as an intermediate electrode (charge recombination layer) by stacking them in an appropriate combination. With such a configuration, the charge recombination layer (intermediate layer) Electrode) It is preferable because the step of forming one layer can be omitted.

The electric conductivity of the charge recombination layer is preferably high from the viewpoint of obtaining high conversion efficiency. Specifically, it is preferably 5 to 50000 S / cm, more preferably 100 to 10,000 S / cm. preferable. The thickness of the charge recombination layer is not particularly limited, but is preferably 1 to 1000 nm, and preferably 5 to 50 nm. By setting the thickness to 1 nm or more, the film surface can be smoothed. On the other hand, by setting the thickness to 1000 nm or less, it is possible to reduce the decrease in the short-circuit current density J _sc (mA / cm ² ).

(Other layers)
The organic photoelectric conversion device of this embodiment may further include other members (other layers) in addition to the above-described members (each layer) in order to improve photoelectric conversion efficiency and improve the lifetime of the device. . Examples of other members include an exciton block layer, a UV absorption layer, a light reflection layer, a wavelength conversion layer, and a smoothing layer. Further, a layer such as a silane coupling agent may be provided in order to make the metal oxide fine particles unevenly distributed in the upper layer more stable. Further, a metal oxide layer may be laminated adjacent to the photoelectric conversion layer of the present invention.

  Moreover, the organic photoelectric conversion element of this invention may have various optical function layers for the purpose of more efficient light reception of sunlight. Examples of the optical functional layer include a light condensing layer such as an antireflection film and a microlens array, and a light diffusion layer that can scatter light reflected by the cathode and enter the power generation layer again.

  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 for 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.

<Method for producing organic photoelectric conversion element>
There is no restriction | limiting in particular in the manufacturing method of the organic photoelectric conversion element of the above-mentioned this form, It can manufacture by referring a conventionally well-known method suitably. Hereinafter, the manufacturing method of the organic photoelectric conversion element shown in FIG. 2 will be described as an example, and a preferable manufacturing method of the organic photoelectric conversion element of this embodiment will be described. However, each process in the manufacturing method can be applied not only to the organic photoelectric conversion element of FIG. 2 but also to the organic photoelectric conversion element shown in FIG. 1 and the tandem type manufacturing as shown in FIG.

  The manufacturing method of the organic photoelectric conversion element of this embodiment includes a step of forming a cathode, a step of forming a photoelectric conversion layer including a p-type organic semiconductor material and an n-type organic semiconductor material on the cathode, and the photoelectric conversion. Forming an anode on the layer. Hereinafter, each process of the manufacturing method of the organic photoelectric conversion element of this form is demonstrated in detail.

  In the manufacturing method of this embodiment, first, a cathode is formed. The method of forming the cathode is not particularly limited, but is easy to operate and can be produced by roll-to-roll using a device such as a die coater. Preferably, the method is a method of applying and drying. Besides this, a commercially available thin film electrode material may be used as it is.

  After forming the cathode as described above, an electron transport layer may be formed on the cathode as necessary. The means for forming the electron transport layer may be either vapor deposition or solution coating, but is preferably solution coating. In the case of forming an electron transport layer using a solution coating method, a solution obtained by dissolving and dispersing the above-described electron transport material in a suitable solvent is coated on the cathode using a suitable coating method and dried. That's fine. The coating methods used for the solution coating method include cast method, spin coating method, blade coating method, wire bar coating method, gravure coating method, spray coating method, dipping (dipping) coating method, bead coating method, air knife coating method. Ordinary methods such as a curtain coating method, an ink jet method, a screen printing method, a relief printing method, an intaglio printing method, an offset printing method, a flexographic printing method, and a Langmuir-Blodgett (LB) method can be used. Among these, it is particularly preferable to use a blade coating method. In addition, although the solid content concentration of the solution used for the coating method may vary depending on the coating method and the film thickness, it is preferably 0.5 to 15% by mass, more preferably 1.0 to 10% by mass. In addition, the temperature of the coating liquid and / or the coating surface during coating is not particularly limited, but is preferably 30 to 120 ° C. from the viewpoint of preventing precipitation and unevenness due to temperature fluctuations during coating and drying. More preferably, it is 50-110 degreeC. Furthermore, there is no restriction | limiting in particular also about the specific form of drying, A conventionally well-known knowledge can be referred suitably. An example of the drying condition is exemplified by a temperature of about 90 to 140 ° C. and a period of several minutes to several tens of minutes. Examples of the apparatus used for drying include a hot plate, hot air drying, an infrared heater, a microwave, and a vacuum dryer. Of course, other drying apparatuses can be used.

  Subsequently, a photoelectric conversion layer including a p-type organic semiconductor and an n-type organic semiconductor is formed on the cathode or the electron transport layer formed as described above. A specific method for forming the photoelectric conversion layer is not particularly limited, but preferably, a solution in which a p-type organic semiconductor and an n-type organic semiconductor are dissolved or dispersed in an appropriate solvent, respectively or collectively. Then, it may be applied on the cathode using an appropriate application method (the specific form is as described above) and dried. After that, it is preferable to perform heating in order to cause removal of residual solvent, moisture, gas, and improvement of mobility and absorption absorption by crystallization of the semiconductor material. When annealing is performed at a predetermined temperature during the manufacturing process, a part of the particles is microscopically aggregated or crystallized and the photoelectric conversion layer can have an appropriate phase separation structure. As a result, the mobility of holes and electrons (carriers) in the photoelectric conversion layer is improved, and high efficiency can be obtained. In this way, the p-type organic semiconductor and the n-type organic semiconductor are uniformly mixed, and a bulk heterojunction organic photoelectric conversion element can be obtained.

  On the other hand, in the case of forming a photoelectric conversion layer (for example, a p-i-n structure) composed of a plurality of layers having different mixing ratios of the p-type organic semiconductor and the n-type organic semiconductor, after applying one layer, the layer is It can be formed by insolubilizing (pigmenting) and then applying another layer.

  In the case of forming a photoelectric conversion layer containing polyalkyleneimine, for example, a solution in which P-type organic semiconductor and / or n-type organic semiconductor, polyalkyleneimine and polyalkyleneimine are dissolved and dispersed in an appropriate solvent is prepared and applied. What is necessary is just to dry.

  The step of forming the photoelectric conversion layer is preferably performed in a glove box under a nitrogen atmosphere so as not to be exposed to oxygen or moisture. Thus, by performing in a nitrogen atmosphere, it is possible to prevent the p-type organic semiconductor from being deteriorated by oxygen or moisture in the air, and to increase the durability of the element.

  Next, a hole transport layer is formed between the photoelectric conversion layer and the anode using a vapor deposition method or a solution coating method, preferably a solution coating method. In addition, it is preferable to perform the process of forming the said positive hole transport layer within the glove box of nitrogen atmosphere similarly to the process of forming the said photoelectric converting layer. Thus, by performing in a nitrogen atmosphere, deterioration of the photoelectric conversion layer due to oxygen or moisture in the air can be prevented, and the durability of the element can be improved.

  The method for forming the hole transport layer containing polyalkyleneimine is not particularly limited. For example, a solution prepared by dissolving and dispersing the hole transport material, polyalkyleneimine and an appropriate solvent is prepared. It is formed by coating and drying.

  Thereafter, an anode is formed on the hole transport layer formed as described above. The means for forming the anode is not particularly limited and may be either a vapor deposition method or a solution coating method, but a vapor deposition method (for example, a vacuum vapor deposition method) is preferably used.

  Furthermore, when layers other than the various layers described above are included, a step for forming these layers can be appropriately added by using a solution coating method, a vapor deposition method, or the like.

  The electrodes (cathode / anode), photoelectric conversion layer, hole transport layer, electron transport layer, and the like can be patterned as necessary. The patterning method is not particularly limited, and a known method can be appropriately applied. For example, when patterning soluble materials used in bulk heterojunction type photoelectric conversion layers, hole transport layers, electron transport layers, etc., only unnecessary portions may be wiped after the entire surface of die coating, dip coating, etc. Alternatively, patterning may be performed by ablation using a carbonic acid laser or the like after film formation, by direct scraping with a scriber, or by direct patterning at the time of coating using a method such as an inkjet method or screen printing. . On the other hand, in the case of insoluble materials used in electrodes, etc., vacuum deposition method, vacuum sputtering method, plasma CVD method, screen printing method using ink in which fine particles of electrode material are dispersed, gravure printing method, ink jet method, etc. Various printing methods, and known methods such as etching or lift-off of the deposited film can be used. Alternatively, the pattern may be formed by transferring a pattern formed on another substrate.

  Moreover, the organic photoelectric conversion element of this embodiment can be sealed as necessary in order to prevent deterioration due to oxygen, moisture, and the like in the environment. There is no restriction | limiting in particular in the method of sealing, It can carry out by the well-known method used with an organic photoelectric conversion element, an organic electroluminescent element, etc. For example, (1) a method of sealing by bonding a cap made of aluminum or glass with an adhesive; (2) a plastic film on which a gas barrier layer such as aluminum, silicon oxide, aluminum oxide or the like is formed and organic photoelectric conversion (3) A method of spin-coating an organic polymer material (polyvinyl alcohol, etc.) having a high gas barrier property; (4) An inorganic thin film (silicon oxide, aluminum oxide, etc.) having a high gas barrier property Alternatively, a method of depositing an organic film (parylene or the like) under vacuum;

  Furthermore, the organic photoelectric conversion element of this embodiment may have a configuration in which the entire element is sealed with two substrates with a barrier from the viewpoint of improving energy conversion efficiency and element lifetime, and preferably includes a moisture getter, an oxygen getter, and the like. It is more preferable that the configuration is as described above.

<Uses of organic photoelectric conversion elements>
According to the other form of this invention, the solar cell which has the organic photoelectric conversion element obtained by the organic photoelectric conversion element which concerns on the above-mentioned 1st form, and the manufacturing method which concerns on a 2nd form is provided. Since the organic photoelectric conversion element of this form has the outstanding photoelectric conversion efficiency and durability, it can be used suitably for the solar cell which uses this as an electric power generation element.

  Moreover, according to the further another form of this invention, the optical sensor array by which the organic photoelectric conversion element mentioned above is arranged in the array form is provided. That is, the organic photoelectric conversion element of this embodiment can also be used as an optical sensor array that converts an image projected on the optical sensor array into an electrical signal using the photoelectric conversion function.

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

<Preparation of p-type semiconductor material (PCDTBT)>
As a p-type semiconductor material, a polythiophene-carbazole-benzothiadiazole copolymer (PCDTBT) is disclosed in Adv. Mater. , Vol. 19, (2007) p2295. The obtained polymer was purified by Soxhlet extraction to obtain PCDTBT having a number average molecular weight (Mn): 35,000 and PDI: 2.0.

<Preparation of p-type semiconductor material (P3HNT)>
As a p-type semiconductor material, vinyl group-substituted polyhexylthiophene (P3HNT) was synthesized with reference to the method described in Macromolecules 2009, 42, p1610-1618. After stopping the polymerization reaction with concentrated hydrochloric acid, the obtained polymer was purified by Soxhlet extraction to obtain P3HNT having a number average molecular weight (Mn): 42,000 and PDI: 1.7.

<Preparation of alkyleneimines and evaluation of amino group content>
The alkyleneimines used in this example were prepared as follows:
(1) Pentaethylenehexamine manufactured by Tokyo Chemical Industry Co., Ltd. was used as a low molecular weight polyethyleneimine (ethyleneimine oligomer) (hereinafter referred to as “Compound 1”).
(2) Wako Pure Chemical Industries, Ltd. # 24313-2 (Mw-2,500) was used as polyethyleneimine having a linear structure (hereinafter referred to as "Compound 2").
(3) Epomin (registered trademark) SP-003 manufactured by Nippon Shokubai Co., Ltd. was used as the polyethyleneimine having a branched chain structure (hereinafter referred to as “compound 3”).
(4) Epomin (registered trademark) SP-006 manufactured by Nippon Shokubai Co., Ltd. was used as the polyethyleneimine having a branched chain structure (hereinafter referred to as “compound 4”).
.
(5) Epomin (registered trademark) RP-20 (modified rate: about 40%) manufactured by Nippon Shokubai Co., Ltd. was used as polyethyleneimine having a branched chain structure and modified with octadecyl isocyanate (hereinafter referred to as “compound”). 5 ”). In addition, the partial structure of the polyethyleneimine modified with the octadecyl isocyanate is shown in the following chemical formula 2.

(6) Epomin (registered trademark) PP-061 (modified ratio: about 90%) manufactured by Nippon Shokubai Co., Ltd. was used as a polyethyleneimine having a branched chain structure and modified with propylene oxide (hereinafter referred to as “compound”). 6 ”). The partial structure of the propylene oxide-modified polyethyleneimine is shown in the following chemical formula 3.

(7) As a polytrimethyleneimine having a branched chain (dendrimer) structure, “propyleneimine octaamine dendrimer (compound name in the catalog)” manufactured by Sigma-Aldrich Japan Co., Ltd. was used (hereinafter referred to as “compound 7”). ).

About the said alkyleneimine, the content rate of a primary, secondary, and tertiary amino group was computed by < ¹³ > C-NMR measurement. ¹³ C-NMR measures the spectrum using an FT-NMR apparatus Lambda400 (manufactured by JEOL Ltd.), and has a peak area derived from carbon bonded to primary, secondary, and tertiary amino groups. The ratio was calculated as the ratio of each amino group. The results are shown in Table 1.

<Production of organic photoelectric conversion element>
[Comparative Example 1] Preparation of Organic Photoelectric Conversion Device SC-101 A 150 nm thick indium tin oxide (ITO) transparent conductive film deposited on a glass substrate (sheet resistance: 10 Ω / □) was used for photolithography and hydrochloric acid. The first electrode (transparent electrode; cathode) was formed by patterning to a width of 20 mm using the wet etching used. The patterned first electrode is ultrasonically cleaned using a mixture of surfactant and ultrapure water, then ultrasonically cleaned using ultrapure water, dried by nitrogen blowing, and finally UV ozone. Washing was performed.

  Next, the substrate on which the first electrode (transparent electrode) is formed is put in a glove box (oxygen concentration 10 ppm, dew point temperature −80 degrees), and a 150 mM TiOx precursor solution is placed on the transparent electrode in a nitrogen atmosphere. It spin-coated (rotation speed 5000rpm, rotation time 60 seconds), and wiped off to the predetermined | prescribed pattern. Then, this was left in the air for 2 hours to hydrolyze the TiOx precursor and then heat-treated at 150 ° C. for 1 hour to form an electron transport layer composed of a TiOx layer having a thickness of about 10 nm.

  The 150 mM TiOx precursor solution was prepared by the following method (sol-gel method). In a 100 mL three-necked flask, 12.5 mL of 2-methoxyethanol and 6.25 mmol of titanium tetraisopropoxide were placed and cooled in an ice bath for 10 minutes. Next, 12.5 mmol of acetylacetone was slowly added and stirred in an ice bath for 10 minutes. Next, this mixed solution was heated at 80 ° C. for 2 hours and then refluxed for 1 hour. This was cooled to room temperature (25 ° C.) and adjusted to a concentration of 150 mM using 2-methoxyethanol to obtain a TiOx precursor solution. The above steps were all performed in a nitrogen atmosphere.

Subsequently, PCDTBT synthesized above and PC ₆₀ BM (manufactured by Frontier Carbon Co., E100H: 6,6-phenyl-C ₆₁ -butyric acid methyl ester) and 1: 1 (mass ratio) to o-dichlorobenzene. A solution A was prepared by dissolving what was mixed at a ratio of 3.0% by mass. This was formed on the electron transport layer so that the dry film thickness was about 100 nm to form a photoelectric conversion layer.

  Then, PEDOT: PSS (Clevios (registered trademark) P4083, manufactured by Heraeus Co., Ltd.) 1 part by mass composed of a conductive polymer and a polyanion, emulogen (0.1 wt%) manufactured by Kao Chemical Co., Ltd. and 2 parts by mass of isopropanol were added. A solution B containing was prepared. The obtained solution B was applied onto the photoelectric conversion layer so as to have a dry film thickness of about 30 nm and dried. Furthermore, it heat-processed for 10 minutes at 100 degreeC, and formed the positive hole transport layer into a film.

  The above processes were all performed in a nitrogen atmosphere.

Next, the substrate on which the series of functional layers has been formed is moved into a vacuum deposition apparatus chamber, the inside of the vacuum deposition apparatus is depressurized to 1 × 10 ⁻⁴ Pa or less, and then Ag is deposited at a deposition rate of 1.0 nm / second. A second electrode was formed by stacking 200 nm of metal. The obtained organic photoelectric conversion element is moved to a nitrogen chamber, sealing is performed using a sealing cavity glass and a UV curable resin, and an organic photoelectric conversion element SC-101 having a light receiving portion of about 5 × 20 mm size is completed. It was.

[Comparative Example 2] Preparation of organic photoelectric conversion element SC-102 After forming the PEDOT: PSS layer, CuPc (copper phthalocyanine, manufactured by Sigma-Aldrich) was deposited to a thickness of 30 nm, and a hole transport layer consisting of two layers SC-102 was produced in the same manner as SC-101 except that was formed. In Table 2 below, the CuPc layer is referred to as a block layer.

[Comparative Example 3] Production of Organic Photoelectric Conversion Device SC-103 SC-103 was prepared in the same manner as SC-101 except that P3HNT was used instead of PCDTBT as the p-type semiconductor material in the formation of the photoelectric conversion layer. Was made.

[Examples 1 to 7] Preparation of organic photoelectric conversion elements SC-104 to SC-110 In the formation of the hole transport layer, when the solution B was prepared, an alkyleneimine was added as shown in Table 2 Produced SC-104 to SC-110 in the same manner as SC-101.

[Examples 8 to 9] Organic photoelectric conversion elements SC-1111 to SC-112
SC-111 to SC-112 were produced in the same manner as SC-101 except that alkyleneimines were added as shown in Table 2 in the preparation of solution A in the formation of the photoelectric conversion layer.

[Example 10] Production of organic photoelectric conversion element SC-113 In the film formation of the photoelectric conversion layer and the hole transport layer, alkyleneimines were added as shown in Table 2 during the preparation of Solution A and Solution B. Except for the above, SC-113 was prepared in the same manner as SC-101.

<Evaluation of photoelectric conversion rate>
Photoelectric conversion element manufactured above was irradiated with light having an intensity of 100 mW / cm ² solar simulator (AM1.5G filter), a superposed mask in which the effective area to 1 cm ² on the light receiving unit, evaluating the I-V characteristic Thus, the short-circuit current density J _sc [mA / cm ² ], the open circuit voltage V _oc [V] and the fill factor FF were measured, and the photoelectric conversion efficiency η was calculated from the following formula 2. The results are shown in Table 2.

<Evaluation of light stability>
The photoelectric conversion element produced above is placed on a hot plate at 85 ° C., a two-wavelength type white LED (Toshiba small SMD) is used as a light source, and the short-circuit current density J _sc measured in the evaluation of the photoelectric conversion efficiency is The light quantity of the LED was adjusted so as to be approximately the same value (about 1 Sun), and light was irradiated for 1000 hours. The short-circuit current density J _sc after light irradiation, was measured according to the measurement method in the evaluation of the photoelectric conversion efficiency was determined the ratio of J _sc after the deterioration to the initial J _sc [%]. The results are shown in Table 2.

  From the result of Table 2, organic photoelectric conversion element SC-104-SC-113 of Examples 1-10 which contain a polyalkyleneimine in any one of a positive hole transport layer and a photoelectric converting layer is a positive hole transport layer and photoelectric conversion. Compared with the organic photoelectric conversion elements SC-101 to SC-103 of Comparative Examples 1 to 3 in which neither of the layers contains polyalkyleneimine, it was shown that the photostability was high and the durability was excellent. . This was considered to be due to the movement of the ionic component in the device being suppressed by the ability of the polyalkyleneimine to capture the ionic component.

  Moreover, it was shown that the initial photoelectric conversion efficiency improves significantly about the organic photoelectric conversion elements SC-1111-SC-113 of Examples 8-10 which contain a polyalkyleneimine in a photoelectric converting layer. This was considered to be due to the favorable morphology formed by the presence of polyalkyleneimine during the production of the photoelectric conversion layer.

  In particular, in the organic photoelectric conversion element SC-113 of Example 10 containing polyalkyleneimine in both the hole transport layer and the photoelectric conversion layer, it was shown that the durability and initial photoelectric conversion efficiency of the element were significantly improved. .

10, 20, 30 organic photoelectric conversion element,
11 Anode,
12 cathode,
14 photoelectric conversion layer,
14a 1st photoelectric conversion layer,
14b second photoelectric conversion layer,
25 substrates,
26 hole transport layer,
27 electron transport layer,
38 Charge recombination layer.

Claims (8)

The first electrode,
The second electrode,
A photoelectric conversion layer including an n-type organic semiconductor and a p-type organic semiconductor, which is present between the first electrode and the second electrode, and the first electrode or the second electrode, and the photoelectric conversion layer And a hole transport layer existing between
At least one of the photoelectric conversion layer and the hole transport layer is an organic photoelectric conversion element containing polyalkyleneimine. The polyalkyleneimine is a branched polyalkyleneimine;
The branched polyalkyleneimine includes a primary amino group, a secondary amino group, and a tertiary amino group,
The organic photoelectric conversion device according to claim 1, wherein the primary amino group is 10 mol% to 50 mol% with respect to 100 mol% of all amino groups in the branched polyalkyleneimine. The polyalkyleneimine includes a modified polyalkyleneimine in which at least one selected from the group consisting of groups represented by the following general formulas 1 to 7 is added to at least a part of a nitrogen atom. 2. The organic photoelectric conversion element according to 2,
In the formula, R ^{1 to} R ⁴ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms;
In the formula, each R ⁵ independently represents a linear or branched alkyl group having 1 to 30 carbon atoms;
In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 30 carbon atoms;
In the formula, R ^{8 to} R ¹¹ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms;
In the formula, each R ¹² independently represents a linear or branched alkyl group having 1 to 30 carbon atoms;
In the formula, each R ¹³ independently represents a linear or branched alkyl group having 1 to 30 carbon atoms;
In the formula, each R ¹⁴ independently represents a linear or branched alkylene group having 1 to 30 carbon atoms, an arylene group, or a heteroarylene group.   The organic photoelectric conversion element according to claim 1, wherein the photoelectric conversion layer includes the polyalkyleneimine.   The organic photoelectric conversion element according to any one of claims 1 to 4, wherein the photoelectric conversion layer and the hole transport layer include the polyalkyleneimine.   The organic photoelectric conversion element of any one of Claims 1-5 in which the said polyalkylene imine contains at least 1 sort (s) selected from the group which consists of polyethyleneimine, polypropyleneimine, and these copolymers.   The organic photoelectric conversion device according to claim 1, wherein the hole transport layer includes a π-conjugated conductive polymer and a polyanion.   The solar cell which has an organic photoelectric conversion element of any one of Claims 1-7.