JPWO2014042091A1 - Conjugated polymer, electron donating organic material, photovoltaic device material and photovoltaic device using the same - Google Patents

Abstract

An object of the present invention is to provide a photovoltaic device having high photoelectric conversion efficiency, and a specific thieno [3, having fluorine at the 3-position and an alkoxycarbonyl group or an alkanoyl group at the 2-position. 4-b] An electron-donating organic material using a conjugated polymer having a benzo [1,2-b: 4,5-b ′] dithiophene skeleton structure having a thiophene skeleton and a heteroaryl group.

Description

  The present invention relates to a conjugated polymer, an electron-donating organic material, a photovoltaic device material and a photovoltaic device using the conjugated polymer.

  Solar cells are attracting attention as an environmentally friendly electrical energy source and an influential energy source for increasing energy problems. Currently, inorganic materials such as single crystal silicon, polycrystalline silicon, amorphous silicon, and compound semiconductors are used as semiconductor materials for photovoltaic elements of solar cells. However, solar cells manufactured using inorganic semiconductors have not been widely used in general households because of high costs. The high cost factor is mainly in the process of manufacturing a semiconductor thin film under vacuum and high temperature. Therefore, organic solar cells using organic semiconductors and organic dyes such as conjugated polymers and organic crystals are being studied as semiconductor materials expected to simplify the manufacturing process.

  However, an organic solar cell using a conjugated polymer or the like has the biggest problem that the photoelectric conversion efficiency is lower than that of a conventional solar cell using an inorganic semiconductor, and has not yet been put into practical use. The photoelectric conversion efficiency of organic solar cells using conventional conjugated polymers is low because of the low absorption efficiency of sunlight and the bound state of exciton where electrons and holes generated by sunlight are difficult to separate. This is because a trap for trapping carriers (electrons and holes) is easily formed, and the generated carriers are easily trapped by the trap, and the mobility of carriers is slow.

  So far, photoelectric conversion elements using organic semiconductors are currently Schottky-type, electron-accepting organic materials (n-type organic semiconductors) that join an electron-donating organic material (p-type organic semiconductor) and a metal having a low work function. And an electron donating organic material (p-type organic semiconductor) can be classified into a heterojunction type. In these elements, only the organic layer (about several molecular layers) at the junction contributes to the photocurrent generation, so that the photoelectric conversion efficiency is low, and its improvement is a problem.

As a method for improving the photoelectric conversion efficiency of the photoelectric conversion element, a junction that contributes to photoelectric conversion by mixing an electron-accepting organic material (n-type organic semiconductor) and an electron-donating organic material (p-type organic semiconductor). There is a method of using a bulk heterojunction type with an increased number of planes. Among them, the conjugated polymer used as the electron donating organic material (p-type organic semiconductor), as the electron accepting organic material, a conductive polymer having a n-type semiconductor characteristics, a fullerene or fullerene derivatives such as C ₆₀ The bulk heterojunction photoelectric conversion element used has been reported.

  By the way, in order to efficiently absorb radiant energy over a wide range of the solar spectrum and improve photoelectric conversion efficiency, an electron-donating organic material with a narrow band gap is useful (for example, Non-Patent Documents 1 and 2). reference). As such a narrow band gap electron-donating organic material, a copolymer combining a thieno [3,4-b] thiophene skeleton and a benzo [1,2-b: 4,5-b ′] dithiophene skeleton is particularly excellent. It has been reported to show photovoltaic characteristics, and many derivatives have been synthesized so far (see, for example, Patent Document 1).

International Publication No. 2011/011545 Pamphlet

E. Bundgaard, F.M. C. Krebs, "Solar Energy Materials & Solar Cells", 2007, 91, 954. H. Zhou, L .; Yang, W.H. You, "Macromolecules", 2012, 45, 607 Y. Liang, D.C. Feng, Y .; Wu, S.W. -T. Tsai, G.A. Li, C.I. Ray, L.M. Yu, "Journal of the American Chemical Society", 2009, 131, 7792. H. -Y. Chen, J. et al. Hou, S .; Zhang, Y. et al. Liang, G.G. Yang, Y. et al. Yang, L.M. Yu, Y. U, G. et al. Li, “Nature Photonics”, 2009, Vol. 3, p. 649 Y. Liang, Z .; Xu, J. et al. Xia, S .; -T. Tsai, Y. et al. Wu, G. Li, C.I. Ray, L.M. Yu, "Advanced Materials", 2010, Vol. 22, p. E135 H. J. et al. Son, W.M. Wang, T.W. Xu, Y. Liang, Y.M. Wu, G. Li, L. Yu, "Journal of the American Chemical Society", 2011, 133, 1885.

  When a photovoltaic device is manufactured using an electron-donating organic material in which the above thieno [3,4-b] thiophene skeleton and a benzo [1,2-b: 4,5-b ′] dithiophene skeleton are combined, It is known that the photoelectric conversion efficiency varies greatly depending on the structure of substituents and side chains. As a type of substituent, introduction of a fluorine atom which is an electron-withdrawing group has an effect of deepening the HOMO level of the electron-donating organic material, and can increase the open-circuit voltage of the photovoltaic element.

  Until now, an electron-donating organic material (Non-Patent Documents 3 to 5) in which a fluorine atom is introduced at the 3-position of the thieno [3,4-b] thiophene skeleton, and benzo [1,2-b: 4,5-b '] An electron-donating organic material in which a fluorine atom is introduced at positions 3 and 7 of the dithiophene skeleton (Non-patent Document 6) has been reported.

  However, the introduction of fluorine atoms does not necessarily have an effect on improving the photoelectric conversion efficiency, and depending on the position of introduction of fluorine atoms in the copolymer and the type of other substituents, the short-circuit current of the photovoltaic device may decrease. As a result, sufficient photoelectric conversion efficiency is not obtained (Non-Patent Documents 3 and 6).

  As an electron-donating organic material capable of increasing the open-circuit voltage of the photovoltaic device and improving the photoelectric conversion efficiency, a fluorine atom at the 3-position of the [3,4-b] thiophene skeleton, an alkoxycarbonyl group at the 2-position, and PTB7 (Non-patent Document 5) in which an alkoxycarbonyl group is introduced at positions 4 and 8 of the benzo [1,2-b: 4,5-b ′] dithiophene skeleton, and position 3 of the [3,4-b] thiophene skeleton PBDTTTT-CF (non-patent document 4) in which an alkanoyl group is introduced at the 2-position, and an alkoxycarbonyl group is introduced at the 4- and 8-positions of the benzo [1,2-b: 4,5-b ′] dithiophene skeleton It has been reported.

  However, in the electron-donating organic material in which the conventional thieno [3,4-b] thiophene skeleton introduced with fluorine atoms and the benzo [1,2-b: 4,5-b ′] dithiophene skeleton are combined, it is high. The open-circuit voltage value and the short-circuit current value cannot be made sufficiently compatible, and high photoelectric conversion efficiency has not been obtained. This is because it is difficult to maintain a high carrier mobility and to form a bulk heterojunction thin film in which an efficient carrier path with an electron-accepting material is formed in an electron-donating organic material into which fluorine atoms are introduced. This is thought to be the cause.

  An object of the present invention is to provide an electron-donating organic material that achieves both deep HOMO, high carrier mobility, and good compatibility with an electron-accepting material, and to provide a photovoltaic device with high photoelectric conversion efficiency. And

  As a result of voluntarily examining the types of substituents and side chains of a copolymer composed of a thieno [3,4-b] thiophene skeleton and a benzo [1,2-b: 4,5-b ′] dithiophene skeleton, The present inventors have found an optimal structure that deepens the HOMO level of the donor organic material and increases the conversion efficiency of the photovoltaic device.

  That is, the present invention is a conjugated polymer having a structure represented by the general formula (1), an electron donating organic material, a photovoltaic element material and a photovoltaic element using the conjugated polymer.

(In the general formula (1), R ¹ represents an optionally substituted alkoxycarbonyl group or alkanoyl group. R ² may be the same or different, and may be substituted heteroaryl groups. N represents the degree of polymerization and represents an integer of 2 to 1,000.)

According to the present invention, a photovoltaic device with high photoelectric conversion efficiency can be provided.

The schematic diagram which showed the one aspect | mode of the photovoltaic device of this invention. The schematic diagram which showed another aspect of the photovoltaic element of this invention. The schematic diagram which showed another aspect of the photovoltaic element of this invention. The schematic diagram which showed another aspect of the photovoltaic element of this invention. The voltage-current density curve of Example 1 (donor acceptor ratio 1: 1).

  The conjugated polymer of this invention contains the structure represented by General formula (1).

  In the general formula (1), a fluorine atom is introduced at the 3-position of the thieno [3,4-b] thiophene skeleton. This makes it possible to deepen the HOMO level. Further, as described later, this does not impair the carrier mobility of the conjugated polymer.

In the general formula (1), R ¹ represents an optionally substituted alkoxycarbonyl group or alkanoyl group. By placing a substituent having a carbonyl group at the 2-position of the thieno [3,4-b] thiophene skeleton, the HOMO level of the conjugated polymer can be deepened, and when used as an electron-donating organic material, It becomes possible to increase the open circuit voltage of the electromotive force element.

  Here, the alkoxycarbonyl group represents an alkyl group via an ester bond. An alkanoyl group refers to an alkyl group via a ketone group.

  The alkyl group is, for example, a saturated aliphatic group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, or a dodecyl group. The hydrocarbon group may be linear, branched, or cyclic, and may be unsubstituted or substituted. Examples of the substituent when substituted include an alkoxy group and halogen. The number of carbon atoms of the alkyl group is preferably 4 or more and 10 or less in order to achieve both sufficient solubility of the electron-donating organic material and carrier mobility.

In the above general formula (1), R ² may be the same or different and represents a heteroaryl group which may be substituted. As described above, the heteroaryl group introduced at positions 4 and 8 of the benzo [1,2-b: 4,5-b ′] dithiophene skeleton allows the 3-position of the thieno [3,4-b] thiophene skeleton to be Even when fluorine atoms are introduced, the HOMO level can be deepened without impairing the carrier mobility of the conjugated polymer. When used as an electron-donating organic material, the photovoltaic device has a high open-circuit voltage and short-circuit current. Can keep.

The number of carbon atoms of the heteroaryl group used for R ² is preferably 2 or more and 6 or less in order to maintain carrier mobility, and in order to suppress twisting with the benzodithiophene skeleton and improve packing properties, it is a 5-membered member having a small molecular size. A thienyl group or a furyl group having a ring structure is particularly preferably used. The substituent on the heteroaryl group is preferably an alkyl group or an alkoxy group having 6 to 10 carbon atoms in order to achieve both solubility of the conjugated polymer and carrier mobility, and these are linear. Can also be branched.

  The halogen is any one of fluorine, chlorine, bromine and iodine. As a substituent of the heteroaryl group, fluorine is preferably used because it can effectively deepen the HOMO level of the conjugated polymer.

  N represents the degree of polymerization and represents an integer of 2 or more and 1,000 or less. By setting n to 5 or more, the carrier mobility of the conjugated polymer can be increased, and an effective carrier path can be formed in the aforementioned bulk heterojunction thin film, so that the photoelectric conversion efficiency can be increased. For ease of synthesis, n is preferably less than 100. The degree of polymerization can be determined from the weight average molecular weight. The weight average molecular weight can be determined by measuring using GPC (gel permeation chromatography) and converting to a polystyrene standard sample. The orientation of the thieno [3,4-b] thiophene skeleton in the conjugated polymer may be random or regioregular.

  Specific examples of the conjugated polymer having the structure represented by the general formula (1) include the following structures. However, n shows the integer of 2 or more and 1,000 or less.

In the conjugated polymer having the structure represented by the general formula (1), the structure represented by the general formula (1) satisfies the structure represented by the general formula (1). For example, structures in which R ¹ and R ² are different may be combined. For example, the following structures are mentioned.
The number attached to the repeating unit enclosed in parentheses represents the ratio of the repeating unit. n represents an integer of 2 or more and 1,000 or less.

  The conjugated polymer having the structure represented by the general formula (1) may be a copolymer further containing a divalent conjugated linking group. In order to maintain the carrier mobility of the conjugated polymer, the divalent conjugated linking group is preferably 20% by weight or less with respect to the entire conjugated polymer. The divalent conjugated linking group is more preferably 10% by weight or less.

  Examples of preferable divalent conjugated linking groups include the following structures. Among these, a structure composed of a thieno [3,4-b] thiophene skeleton is preferable for maintaining the carrier mobility of the conjugated polymer.

Here, R ^{3 to} R ⁵³ may be the same or different and are selected from hydrogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkylthioester group, an alkanoyl group, an aryl group, a heteroaryl group, and a halogen.

  The conjugated polymer having the structure represented by the general formula (1) is similar to, for example, a method similar to the method described in Patent Document 1 or a method described in Non-Patent Document 3. Can be synthesized by the above method.

The photovoltaic device material of the present invention may be composed of only an electron-donating organic material using a conjugated polymer having a structure represented by the general formula (1), or other electron-donating organic material. May be included. Examples of other electron-donating organic materials include polythiophene polymers, benzothiadiazole-thiophene derivatives, benzothiadiazole-thiophene copolymers, poly-p-phenylene vinylene polymers, poly-p-phenylene polymers. Conjugated polymers such as polymers, polyfluorene polymers, polypyrrole polymers, polyaniline polymers, polyacetylene polymers, polythienylene vinylene polymers, H ₂ phthalocyanine (H ₂ Pc), copper phthalocyanine ( CuPc), phthalocyanine derivatives such as zinc phthalocyanine (ZnPc), porphyrin derivatives, N, N′-diphenyl-N, N′-di (3-methylphenyl) -4,4′-diphenyl-1,1′-diamine ( TPD), N, N′-dinaphthyl-N, N′-diphenyl-4,4′-diphenyl Triarylamine derivatives such as -1,1'-diamine (NPD), carbazole derivatives such as 4,4'-di (carbazol-9-yl) biphenyl (CBP), oligothiophene derivatives (terthiophene, quarterthiophene, And low molecular organic compounds such as cithiophene and octithiophene).

  The conjugated polymer having the structure represented by the general formula (1) is an electron donating organic material exhibiting p-type semiconductor characteristics, and the photovoltaic device material of the present invention is intended to obtain higher photoelectric conversion efficiency. It is preferable to combine with an electron-accepting organic material (n-type organic semiconductor).

Examples of the electron-accepting organic material exhibiting n-type semiconductor characteristics include 1,4,5,8-naphthalene tetracarboxyl dianhydride (NTCDA) and 3,4,9,10-perylene tetracarboxyl dianhydride (PTCDA). ), 3,4,9,10-perylenetetracarboxylic bisbenzimidazole (PTCBI), N, N′-dioctyl-3,4,9,10-naphthyltetracarboxydiimide (PTCDI-C8H), 2- (4 -Biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole (PBD), 2,5-di (1-naphthyl) -1,3,4-oxadiazole (BND) Oxazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2 , 4-triazole (TAZ) and other triazole derivatives, phenanthroline derivatives, phosphine oxide derivatives, fullerene compounds (C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ and the like) [6,6] -phenyl C61 butyric acid methyl ester ([6,6] -PCBM), [5,6] -phenyl C61 butyric acid methyl ester ([5,6] -PCBM) [6,6] -phenyl C61 butyric acid hexyl ester ([6,6] -PCBH), [6,6] -phenyl C61 butyric acid dodecyl ester ([6,6] -PCBD), phenyl C71 buty butyric acid methyl ester _(PC 70 BM), phenyl C85 Buchirikkuashi' Methyl ester _(PC 84 BM), etc.), carbon nanotubes (CNT), poly -p- phenylene vinylene-based polymer derivatives obtained by introducing cyano group into (CN-PPV) and the like. Among these, fullerene compounds are preferably used because of their high charge separation speed and electron transfer speed. Among fullerene compounds, C ₇₀ derivatives (such as the above PC ₇₀ BM) are more preferable because they are excellent in light absorption characteristics and can obtain higher photoelectric conversion efficiency.

  In a photovoltaic device material combining an electron-donating organic material and an electron-accepting organic material using a conjugated polymer having a structure represented by the general formula (1) of the present invention, an electron-donating organic material and The content ratio (weight fraction) of the electron-accepting organic material is not particularly limited, but the content ratio (donor-acceptor ratio) of the electron-donating organic material and the electron-accepting organic material is in the range of 1:99 to 99: 1. More preferably, it is the range of 10: 90-90: 10, More preferably, it is the range of 20: 80-60: 40.

  The electron-donating organic material and the electron-accepting organic material may be used as a mixture or laminated. Although it does not specifically limit as a mixing method, After adding to a solvent in a desired ratio, the method of making it melt | dissolve in a solvent combining 1 type or multiple types of methods, such as a heating, stirring, and ultrasonic irradiation, is mentioned. . As will be described later, when the photovoltaic element material forms a single organic semiconductor layer, the above-mentioned content ratio is the content ratio of the electron-donating organic material and the electron-accepting organic material contained in the single layer. When the organic semiconductor layer has a laminated structure of two or more layers, it means the content ratio of the electron donating organic material and the electron accepting organic material in the whole organic semiconductor layer.

  In order to further improve the photoelectric conversion efficiency, it is preferable to remove impurities that can trap carriers as much as possible. In the present invention, an electron donating organic material using a conjugated polymer having a structure represented by the general formula (1) and a method for removing impurities from the electron accepting organic material are not particularly limited. Methods, recrystallization methods, sublimation methods, reprecipitation methods, Soxhlet extraction methods, molecular weight fractionation methods by GPC, filtration methods, ion exchange methods, chelate methods, and the like can be used. In general, a column chromatography method, a recrystallization method, and a sublimation method are preferably used for purification of a low molecular weight organic material. On the other hand, for purification of high molecular weight compounds, reprecipitation method, Soxhlet extraction method, molecular weight fractionation method by GPC is preferably used when removing low molecular weight components, and reprecipitation method or the like when removing metal components. A chelate method or an ion exchange method is preferably used. A plurality of these methods may be combined.

  Next, the photovoltaic element of the present invention will be described. The photovoltaic device of the present invention has at least a positive electrode and a negative electrode, and includes the photovoltaic device material of the present invention between them. FIG. 1 is a schematic view showing an example of the photovoltaic element of the present invention. In FIG. 1, reference numeral 1 is a substrate, reference numeral 2 is a positive electrode, reference numeral 3 is an organic semiconductor layer containing the photovoltaic element material of the present invention, and reference numeral 4 is a negative electrode. The photovoltaic element of the present invention may be in the order of substrate 1 / negative electrode 4 / organic semiconductor layer 3 / positive electrode 2 as illustrated in FIG.

  The organic semiconductor layer 3 contains the photovoltaic element material of the present invention. That is, an electron-donating organic material and an electron-accepting organic material using a conjugated polymer having a structure represented by the general formula (1) are included. When the organic semiconductor layer 3 that is an organic power generation layer of the photovoltaic element includes an electron donating organic material and an electron accepting material, these materials may be mixed or stacked, but are mixed. It is preferable. That is, as shown in FIGS. 1 and 2, even if the organic semiconductor layer containing the photovoltaic element material is a layer in which an electron-donating organic material and an electron-accepting organic material are mixed, FIGS. As described above, the organic semiconductor layer containing the photovoltaic element material may have a laminated structure of a layer having an electron-donating organic material and a layer having an electron-accepting organic material. It is preferable that the organic semiconductor layer containing is a layer in which an electron donating organic material and an electron accepting organic material are mixed.

  A bulk heterojunction photovoltaic device that increases the bonding surface between the electron-donating organic material and the electron-accepting organic material that contributes to photoelectric conversion by mixing the electron-donating organic material and the electron-accepting organic material is preferable. In the organic semiconductor layer 3 which is this bulk heterojunction type organic power generation layer, the electron donating organic material and the electron accepting organic material using the conjugated polymer having the structure represented by the general formula (1) are nanometers. It is preferable that phase separation is performed at a size of. The domain size of this phase separation structure is not particularly limited, but is usually 1 nm or more and 50 nm or less.

  In addition, when an electron-donating organic material and an electron-accepting organic material using a conjugated polymer having a structure represented by the general formula (1) are stacked, an electron-donating organic material exhibiting p-type semiconductor characteristics The layer having the material is preferably on the positive electrode side, and the layer having an electron-accepting organic material exhibiting n-type semiconductor characteristics is preferably on the negative electrode side. An example of the photovoltaic element in the case where the organic semiconductor layer 3 is thus laminated is shown in FIGS. Reference numeral 5 denotes a layer having an electron donating organic material using a conjugated polymer having a structure represented by the general formula (1), and reference numeral 6 denotes a layer having an electron accepting organic material. The organic semiconductor layer preferably has a thickness of 5 nm to 500 nm, more preferably 30 nm to 300 nm. The layer having an electron donating organic material of the present invention preferably has a thickness of 1 nm to 400 nm, more preferably 15 nm to 150 nm.

In the photovoltaic device of the present invention, it is preferable that either the positive electrode 2 or the negative electrode 4 has light transmittance. The light transmittance of the electrode is not particularly limited as long as incident light reaches the organic semiconductor layer 3 and an electromotive force is generated. Here, the light transmittance in the present invention is a value obtained by [transmitted light intensity (W / m ² ) / incident light intensity (W / m ² )] × 100 (%). The thickness of the electrode may be in a range having light transparency and conductivity, and is preferably 20 nm to 300 nm, although it varies depending on the electrode material. The other electrode is not necessarily light-transmitting as long as it has conductivity, and the thickness is not particularly limited.

  Electrode materials include gold, platinum, silver, copper, iron, zinc, tin, aluminum, indium, chromium, nickel, cobalt, scandium, vanadium, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, etc. In addition, metal oxides such as indium, tin, molybdenum and nickel, composite metal oxides (indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), gallium zinc oxide ( GZO)), alkali metals and alkaline earth metals, specifically lithium, magnesium, sodium, potassium, calcium, strontium, barium, and the like are also preferably used. Furthermore, an electrode made of an alloy made of the above metal or a laminate of the above metal is also preferably used. Further, graphite, graphite intercalation compounds, carbon nanotubes, graphene, polyaniline and derivatives thereof, and electrodes containing polythiophene and derivatives thereof are also preferably used. At this time, at least one of the positive electrode and the negative electrode is preferably transparent or translucent. The electrode material may be a mixed layer composed of two or more materials and a laminated structure.

  Here, the conductive material used for the positive electrode 2 is preferably one that is in ohmic contact with the organic semiconductor layer 3. Furthermore, when a hole transport layer described later is used, it is preferable that the conductive material used for the positive electrode 2 is in ohmic contact with the hole transport layer. In addition, the conductive material used for the negative electrode 4 is preferably one that is in ohmic contact with the organic semiconductor layer 3 or the electron transport layer. Here, as a method for improving the bonding, a method of introducing a metal fluoride such as lithium fluoride (LiF) or cesium fluoride as an electron extraction layer into the negative electrode can be mentioned. By introducing the electron extraction layer, it is possible to improve the extraction current.

  The substrate 1 is an inorganic substrate such as an alkali-free glass, quartz glass, aluminum, iron, copper, or an alloy such as stainless steel, on which an electrode material or an organic semiconductor layer can be laminated, depending on the type and application of the photoelectric conversion material. Films and plates produced by any method from organic materials such as materials, polyester, polycarbonate, polyolefin, polyamide, polyimide, polyphenylene sulfide, polyparaxylene polymethyl methacrylate, epoxy resin and fluorine-based resin can be used. In the case where light is incident from the substrate side and used, it is preferable that each substrate described above has a light transmittance of 80% or more.

In the present invention, a hole transport layer may be provided between the positive electrode 2 and the organic semiconductor layer 3. As a material for forming the hole transport layer, polythiophene polymer, poly-p-phenylene vinylene polymer, polyfluorene polymer, polypyrrole polymer, polyaniline polymer, polyfuran polymer, polypyridine polymer, polycarbazole Conductive polymers such as polymers, low molecular organic compounds exhibiting p-type semiconductor properties such as phthalocyanine derivatives (H ₂ Pc, CuPc, ZnPc, etc.), porphyrin derivatives, acene compounds (tetracene, pentacene, etc.), graphene, Carbon compounds such as graphene oxide, molybdenum oxides such as MoO ₃ (MoO _x ), tungsten oxides such as WO ₃ (WO _x ), nickel oxides such as NiO (NiO _x ), vanadium oxides such as V ₂ O ₅ (VO _x) ), zirconium oxide such as ZrO _{2 (ZrO} x) Copper oxide such as Cu ₂ O _(CuO x), copper iodide, ruthenium oxide, such as RuO ₄ (RuO _x), inorganic compounds such as ruthenium oxide (ReO _x), such as Re ₂ O ₇ is preferably used. In particular, polyethylenedioxythiophene (PEDOT), which is a polythiophene polymer, PEDOT to which polystyrene sulfonate (PSS) is added, molybdenum oxide, vanadium oxide, and tungsten oxide are preferably used. Further, the hole transport layer may be a layer made of a single compound, or a mixed layer made of two or more compounds and a laminated structure. The hole transport layer preferably has a thickness of 5 nm to 600 nm, more preferably 10 nm to 200 nm.

  In the photovoltaic device of the present invention, an electron transport layer may be provided between the organic semiconductor layer 3 and the negative electrode 4. Although it does not specifically limit as a material which forms an electron carrying layer, The above-mentioned electron-accepting organic material (NTCDA, PTCDA, PTCDI-C8H, an oxazole derivative, a triazole derivative, a phenanthroline derivative, a phosphine oxide derivative, a phosphine sulfide derivative Organic materials exhibiting n-type semiconductor properties such as quinoline derivatives, fullerene compounds, CNT, CN-PPV, etc. are preferably used. Also, ionic substituted fluorene-based polymers ("Advanced Materials", 2011, 23, 4636-4463, "Organic Electronics", 2009, 10, 476-500). ) And combinations of ionic substituted fluorene polymers and substituted thiophene polymers (“Journal of American Chemical Society” 2011, 133, 8416-8419), Polyethylene oxide ("Advanced Materials", 2007, Vol. 19, 1835) -1838) can also be used as the electron transport layer.

  Also, compounds having an ionic group, such as ammonium salts, amine salts, pyridinium salts, imidazolium salts, phosphonium salts, carboxylates, sulfonates, phosphates, sulfate esters, phosphate ester salts, sulfates , Nitrates, acetonates, oxoacid salts, and metal complexes can also be used as the electron transport layer. Specifically, ammonium chloride, ammonium acetate, ammonium phosphate, hexyltrimethylammonium bromide, tetrabutylammonium bromide, octadecyltrimethylammonium bromide, hexadecylpyridinium bromide, 1-butyl-3-methylimidazolium bromide, tributylhexadecylphosphonium bromide , Zinc formate, zinc acetate, zinc propionate, zinc butyrate, zinc oxalate, sodium heptadecafluorononanoate, sodium myristate, sodium benzoate, sodium 1-hexadecanesulfonate, sodium dodecyl sulfate, sodium monododecyl phosphate, Zinc acetylacetonate, ammonium chromate, ammonium metavanadate, ammonium molybdate, hexafluorozirconium acid Examples include monium, sodium tungstate, ammonium tetrachlorozincate, tetraisopropyl orthotitanate, lithium nickelate, potassium permanganate, silver phenanthroline complex, AgTCNQ, and compounds used in the electron transport layer described in JP2013-58714. It is done.

Further, titanium oxide such as TiO ₂ (TiO _x ), zinc oxide such as ZnO (ZnO _x ), silicon oxide such as SiO ₂ (SiO _x ), tin oxide such as SnO ₂ (SnO _x ), oxidation such as WO ₃ Tungsten oxide (TaO _x ) such as tungsten (WO _x ), Ta ₂ O _3, barium titanate (BaTi _x O _y ) such as BaTiO ₃ , barium zirconate (BaZr _x O _y ) such as BaZrO ₃ , ZrO _2, etc. Zirconium oxide (ZrO _x ), hafnium oxide (HfO _x ) such as HfO ₂ , aluminum oxide (AlO _x ) such as Al ₂ O _3, yttrium oxide (YO _x ) such as Y ₂ O ₃ , and silicon such as ZrSiO ₄ Of metal oxides such as zirconium oxide (ZrSi _x O _y ), silicon nitride (SiN _x ) such as Si ₃ N ₄ Semiconductors such as nitrides, cadmium sulfide (CdS _x ) such as CdS, zinc selenide (ZnSe _x ) such as ZnSe, zinc sulfide (ZnS _x ) such as ZnS, cadmium telluride (CdTe _x ) such as CdTe Inorganic materials such as these are also preferably used as the electron transport layer.

  As a method of forming an electron transport layer with the inorganic material, a method of forming a layer by applying a precursor solution such as a metal salt or metal alkoxide and then heating, or applying a nanoparticle dispersion on a substrate There are methods for forming layers. At this time, depending on the heating temperature and time, and the synthesis conditions of the nanoparticles, the reaction does not proceed completely, and it becomes an intermediate product by partially hydrolyzing or partially condensing. Or a mixture of a precursor, an intermediate organism, and an end product.

  Further, the phenanthroline derivative is not particularly limited. For example, bathocuproin (BCP), bathophenanthrene (Bphen), 2-naphthalen-2-yl-4,7-diphenyl-1,10-phenanthroline ( Phenanthroline monomer compounds such as HNBphen), 2,9-bisnaphthalen-2-yl-4,7-diphenyl-1,10-phenanthroline (NBphen), and phenanthroline multimeric compounds described in JP 2012-39097 A. . The phenanthroline dimer compound is a compound such as the compound described in JP 2012-39097 A and is a compound represented by the following general formula (2).

Here, R ^{54 to} R ⁶⁰ may be the same or different and are selected from hydrogen, an alkyl group, and an aryl group. A is a divalent aromatic hydrocarbon group. The substituents having two phenanthroline skeletons may be the same or different. Here, the alkyl group represents a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group, or a butyl group, and the aryl group represents, for example, a phenyl group, a tolyl group, a biphenyl group, a naphthyl group, a phenanthryl group, An aromatic hydrocarbon group such as an anthryl group is shown and may be unsubstituted or substituted. As for carbon number of an alkyl group or an aryl group, about 1-20 are preferable. Further, the groups having two phenanthroline skeletons may be the same or different.

The phosphine oxide derivative is not particularly limited, and examples thereof include phosphine compounds such as phenyl dipyrenyl phosphine oxide (POPy ₂ ).

  In addition, the quinoline derivative is not particularly limited, and examples thereof include compounds such as 8-hydroxyquinolate lithium (Liq) and tris (8-hydroxyquinolate) aluminum.

  Although the mechanism for improving the properties of these electron transport layers is not clear, the energy barrier is reduced at the interface junction with the negative electrode, and the negative electrode interface of excitons generated in the electron-donating organic semiconductor and the electron-accepting organic semiconductor. It is considered that the electron extraction efficiency and the charge generation efficiency are improved by preventing the deactivation of the catalyst.

  Among the electron transport layers, a phenanthroline derivative is preferably used because of its ability to transport electrons and to obtain a homogeneous film. Furthermore, a phenanthroline multimer compound is preferably used because a stable film having a high glass transition point can be easily obtained, and a phenanthroline dimer compound is more preferably used in consideration of easiness of synthesis. Among the phenanthroline dimer compounds, A in the general formula (2) is a substituted or unsubstituted phenylene group or a substituted or non-substituted phenoxy group from the balance of sublimation property and thin film forming ability during thin film formation such as vacuum deposition. It is preferably a substituted naphthylene group.

  The electron transport layer preferably has a thickness of 0.1 nm to 600 nm, more preferably 1 nm to 200 nm, and still more preferably 1 nm to 20 nm. The electron transport layer may be a layer made of a single compound or a layer made of two or more compounds. Further, the electron transport layer includes an alkali metal or alkaline earth metal, specifically, a compound such as lithium, magnesium, calcium, or a metal fluoride such as lithium fluoride or cesium fluoride, and the material for the electron transport layer. It may be a mixed layer or a laminated structure with them.

  In the photovoltaic device of the present invention, two or more organic semiconductor layers may be laminated via one or more intermediate electrodes to form a series junction. Such a configuration is sometimes called a tandem configuration. For example, a tandem configuration of substrate / positive electrode / first organic semiconductor layer / intermediate electrode / second organic semiconductor layer / negative electrode can be given. In addition, a tandem configuration of substrate / negative electrode / first organic semiconductor layer / intermediate electrode / second organic semiconductor layer / positive electrode may be mentioned. By adopting the tandem configuration in this way, the open circuit voltage can be improved. Note that the hole transport layer described above may be provided between the positive electrode and the first organic semiconductor layer and between the intermediate electrode and the second organic semiconductor layer, and between the first organic semiconductor layer and the intermediate electrode. The hole transport layer described above may be provided between the second organic semiconductor layer and the negative electrode.

In such a tandem configuration, at least one of the organic semiconductor layers contains the photovoltaic device material of the present invention, and the other layers are represented by the general formula (1) in order not to reduce the short-circuit current. It is preferable to include an electron-donating organic material having a band gap different from that of the electron-donating organic material using a conjugated polymer having a structure. Examples of such an electron-donating organic material include the polythiophene polymer, poly-p-phenylene vinylene polymer, poly-p-phenylene polymer, polyfluorene polymer, polypyrrole polymer, polyaniline described above. Polymer, polyacetylene polymer, polythienylene vinylene polymer, benzothiadiazole polymer (for example, PCPDTBT (poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [ 2,1-b; 3,4-b ′] dithiophene) -alt-4,7- (2,1,3-benzothiadiazole)]) and PSBTBT (poly [(4,4-bis- (2-ethylhexyl)). ) Dithino [3,2-b: 2 ′, 3′-d] silole) − , 6-diyl-alt- (2,1,3 -benzothiadiazole) -4,7-diyl])) conjugated polymer or, _{H 2} phthalocyanine such as _(H 2 Pc), copper phthalocyanine (CuPc), zinc phthalocyanine Phthalocyanine derivatives such as (ZnPc), porphyrin derivatives, N, N′-diphenyl-N, N′-di (3-methylphenyl) -4,4′-diphenyl-1,1′-diamine (TPD), N, Triarylamine derivatives such as N′-dinaphthyl-N, N′-diphenyl-4,4′-diphenyl-1,1′-diamine (NPD), 4,4′-di (carbazol-9-yl) biphenyl ( Carbazole derivatives such as CBP), oligothiophene derivatives (terthiophene, quarterthiophene, sexithiophene, octithiophene, etc. Low molecular organic compounds and the like.

  In addition, the material for the intermediate electrode used here is preferably a material having high conductivity, for example, the above-mentioned metals such as gold, platinum, chromium, nickel, lithium, magnesium, calcium, tin, silver, aluminum, and transparent Metal oxides such as indium, tin, and molybdenum, composite metal oxides (indium tin oxide (ITO), indium zinc oxide (IZO), etc.), alloys composed of the above metals, and laminates of the above metals , Polyethylenedioxythiophene (PEDOT), and those obtained by adding polystyrene sulfonate (PSS) to PEDOT. The intermediate electrode preferably has a light transmission property, but even a material such as a metal having a low light transmission property can often ensure a sufficient light transmission property by reducing the film thickness.

  Next, an example is given and demonstrated about the manufacturing method of the photovoltaic device of this invention. A transparent electrode such as ITO (corresponding to a positive electrode in this case) is formed on the substrate by sputtering or the like. A solution is prepared by dissolving an electron donating organic material using a conjugated polymer having a structure represented by the general formula (1) and, if necessary, a material for a photoelectric conversion element containing an electron accepting organic material in a solvent, An organic semiconductor layer is formed by coating on the transparent electrode.

  The solvent used at this time is not particularly limited as long as the organic semiconductor can be appropriately dissolved or dispersed in the solvent, but an organic solvent is preferable, for example, hexane, heptane, octane, isooctane, nonane, decane, cyclohexane, decalin. , Aliphatic hydrocarbons such as bicyclohexyl, alcohols such as methanol, ethanol, butanol, propanol, ethylene glycol, glycerin, ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, isophorone, ethyl acetate, butyl acetate, Esters such as methyl lactate, γ-butyrolactone, diethylene glycol monobutyl ether acetate, dimethyl carbonate, ethyl ether, methyl tertiary butyl ether, tetrahydrofuran, 1 4-dioxane, tetrahydropyran, 3,4-dihydro-2H-pyran, isochroman, ethers such as ethylene glycol monomethyl ether, diglyme, amines such as ammonia and ethanolamine, N, N-dimethylformamide, dimethylacetamide, N -Amides such as methyl-2-pyrrolidone, sulfones such as sulfolane, sulfoxides such as dimethyl sulfoxide, thiols such as carbon disulfide and 1,8-octanedithiol, nitriles such as acetonitrile and acrylonitrile, acetic acid, lactic acid Fatty acids such as, heterocyclic compounds such as furan, thiophene, pyrrole, pyridine, benzene, toluene, xylene, ethylbenzene, cumene, n-butylbenzene, sec-butylbenzene, tert-butylben Zen, styrene, mesitylene, 1,2,4-trimethylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dipentylbenzene, dodecylbenzene, ethynylbenzene, tetralin, anisole, phenetole, butylphenyl ether, pentylphenyl ether, Veratrol, 1,3-dimethoxybenzene, 1,2,4-trimethoxybenzene, 3,4,5-trimethoxytoluene, 2-methoxytoluene, 2,5-dimethylanisole, o-chlorophenol, chlorobenzene, dichlorobenzene , Trichlorobenzene, 1-chloronaphthalene, 1-bromonaphthalene, 1-methylnaphthalene, o-diiodobenzene, acetophenone, 2,3-benzofuran, 2,3-dihydrobenzofuran Aromatic hydrocarbons such as 1,4-benzodioxane, phenyl acetate, methyl benzoate, cresol, aniline, nitrobenzene, dichloromethane, 1,2-dichloroethylene, trichloroethylene, tetrachloroethylene, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, 1 , 3-dichloropropane, 1,1,1,2-tetrachloroethane, 1,1,1,3-tetrachloropropane, 1,2,2,3-tetrachloropropane, 1,1,2,3-tetrachloropropane, Pentachloropropane, hexachloropropane, heptachloropropane, 1-bromopropane, 1,2-dibromopropane, 2,2-dibromopropane, 1,3-dibromopropane, 1,2,3-tribromopropane, 1,4-dibromo Butane, 1,5- Bromopentane, 1,6-dibromohexane, 1,7-dibromoheptane, 1,8-dibromooctane, 1-iodopropane, 1,3-diiodopropane, 1,4-diiodobutane, 1,5-diiodopentane 1,6-diiodohexane, 1,7-diiodoheptane, 1,8-diiodooctane, and other halogen hydrocarbons. Among these, toluene, xylene, mesitylene, 1,2,4-trimethylbenzene, tetralin, anisole, phenetole, veratrol, 1,3-dimethoxybenzene, 1,2,4-trimethoxybenzene, 3,4,5- Aromatic hydrocarbons such as trimethoxytoluene, 2-methoxytoluene, 2,5-dimethylanisole, chlorobenzene, dichlorobenzene, trichlorobenzene, 1-chloronaphthalene, chloroform, dichloromethane, 1,2-dibromopropane, 1, 3-dibromopropane, 1,2,3-tribromopropane, 1,4-dibromobutane, 1,6-dibromohexane, 1,8-dibromooctane, 1,3-diiodopropane, 1,4-diiodobutane, 1,5-diiodopentane, 1,6-diiodohexane Emissions, 1,7-diiodo-heptane, 1,8-halogen hydrocarbons such as diiodooctane, and the like. Two or more of these may be mixed and used.

  When an organic semiconductor layer is formed by mixing an electron-donating organic material and an electron-accepting organic material using a conjugated polymer having a structure represented by the general formula (1), an electron-donating organic material and an electron A receptive organic material is added to a solvent in a desired ratio, dissolved by a method such as heating, stirring, and ultrasonic irradiation to form a solution, which is applied onto a transparent electrode. In this case, the photoelectric conversion efficiency of the photovoltaic element can be improved by using a mixture of two or more solvents. This is presumably because the electron-donating organic material and the electron-accepting organic material undergo phase separation at the nano level, and a carrier path that forms a path for electrons and holes is formed.

  As the solvent to be combined, an optimal combination type can be selected depending on the types of the electron donating organic material and the electron accepting organic material to be used. In the case where an electron donating organic material using a conjugated polymer having a structure represented by the general formula (1) is used, preferred solvents to be combined include chloroform and chlorobenzene among the above. In this case, the mixing volume ratio of each solvent is preferably in the range of chloroform: chlorobenzene = 5: 95 to 95: 5, more preferably in the range of chloroform: chlorobenzene = 10: 90 to 90:10.

  Further, when an organic semiconductor layer is formed by laminating an electron donating organic material and an electron accepting organic material using a conjugated polymer having a structure represented by the general formula (1), for example, an electron donating organic After the material solution is applied to form a layer having an electron-donating organic material, the electron-accepting organic material solution is applied to form a layer. Here, when the electron-donating organic material and the electron-accepting organic material are low molecular weight substances having a molecular weight of about 1000 or less, it is possible to form a layer using a vapor deposition method.

  For organic semiconductor layer formation, spin coating, blade coating, slit die coating, screen printing coating, bar coater coating, mold coating, printing transfer method, dip pulling method, ink jet method, spray method, vacuum deposition method, etc. This method may be used, and the formation method may be selected according to the characteristics of the organic semiconductor layer to be obtained, such as film thickness control and orientation control. For example, when spin coating is performed, the concentration of electron donating organic material and electron accepting organic material using a conjugated polymer having a structure represented by the general formula (1) is 1 to 20 g / l (electrons). The weight of the electron donating organic material and the electron accepting organic material with respect to the volume of the solution containing the donating organic material, the electron accepting organic material, and the solvent is preferable. It is possible to easily obtain a homogeneous organic semiconductor layer.

  In order to remove the solvent, the formed organic semiconductor layer may be subjected to an annealing treatment under reduced pressure or in an inert atmosphere (in a nitrogen or argon atmosphere). A preferable temperature for the annealing treatment is 40 ° C to 300 ° C, more preferably 50 ° C to 200 ° C. Further, by performing the annealing process, the effective area where the stacked layers permeate and contact each other at the interface increases, and the short-circuit current can be increased. This annealing treatment may be performed after the formation of the negative electrode.

  Next, a metal electrode such as Al (corresponding to a negative electrode in this case) is formed on the organic semiconductor layer by vacuum deposition or sputtering. When the metal electrode is vacuum-deposited using a low molecular organic material for the electron transport layer, it is preferable that the metal electrode is continuously formed while maintaining the vacuum.

  When a hole transport layer is provided between the positive electrode and the organic semiconductor layer, a desired p-type organic semiconductor material (such as PEDOT) is applied on the positive electrode by spin coating, bar coating, blade casting, or the like. Then, the solvent is removed using a vacuum thermostat or a hot plate to form a hole transport layer. In the case of using a low molecular organic material such as a phthalocyanine derivative or a porphyrin derivative, it is also possible to apply a vacuum vapor deposition method using a vacuum vapor deposition machine.

When an electron transport layer is provided between the organic semiconductor layer and the negative electrode, a desired n-type organic semiconductor material (such as fullerene derivatives) or an n-type inorganic semiconductor material (such as titanium oxide gel) is spin-coated on the organic semiconductor layer. After coating by a coating method, a casting method using a blade, a spray method, or the like, the solvent is removed using a vacuum thermostat or a hot plate to form an electron transport layer. When using a low molecular organic material such as a phenanthroline derivative or C _60, it is also possible to apply a vacuum deposition method using a vacuum deposition machine.

  The photovoltaic element of the present invention can be applied to various photoelectric conversion devices using a photoelectric conversion function, an optical rectification function, and the like. For example, it is useful for photovoltaic cells (such as solar cells), electronic devices (such as optical sensors, optical switches, and phototransistors), optical recording materials (such as optical memories), and imaging devices.

Hereinafter, the present invention will be described more specifically based on examples. In addition, this invention is not limited to the following Example. Of the compounds used in the examples and the like, those using abbreviations are shown below.
ITO: indium tin oxide PEDOT: polyethylene dioxythiophene PSS: polystyrene sulfonate PC ₇₀ BM: phenyl C71 butyric acid methyl ester Eg: band gap HOMO: highest occupied molecular orbital Isc: short circuit current density Voc: open circuit voltage FF: fill Factor η: Photoelectric conversion efficiency For the ¹ H-NMR measurement, an FT-NMR apparatus (JEOL JNM-EX270 manufactured by JEOL Ltd.) was used.

Moreover, the average molecular weight (number average molecular weight, weight average molecular weight) was calculated by an absolute calibration curve method using a GPC apparatus (manufactured by TOSOH Co., Ltd., which was supplied with chloroform, a high-speed GPC apparatus HLC-8320GPC). The degree of polymerization n was calculated by the following formula.
Degree of polymerization n = [(weight average molecular weight) / (molecular weight of repeating unit)]
The light absorption edge wavelength is an ultraviolet-visible absorption spectrum (measurement wavelength) of a thin film formed on glass with a thickness of about 60 nm using a U-3010 spectrophotometer manufactured by Hitachi, Ltd. (Range: 300-900 nm).

The band gap (Eg) was calculated from the light absorption edge wavelength by the following equation. The thin film was formed by spin coating using chloroform as a solvent.
Eg (eV) = 1240 / light absorption edge wavelength of thin film (nm)
In addition, the highest occupied molecular orbital (HOMO) level was determined by using a surface analyzer (in-air ultraviolet photoelectron spectrometer AC-2 type, manufactured by Riken Kikai Co., Ltd.) for a thin film formed on ITO glass with a thickness of about 60 nm. ). The thin film was formed by spin coating using chloroform as a solvent.

  Whether the material is an electron-donating organic material or an electron-accepting organic material, that is, p-type semiconductor characteristics or n-type semiconductor characteristics can be evaluated by measuring the above-described thin film using FET or energy level.

Synthesis example 1
Compound A-1 was synthesized by the method shown in Scheme 1. In addition, the compound (1-i) described in Synthesis Example 1 was obtained by referring to the compound (Journal of the American Chemical Society), 2009, Vol. 131, pages 7792-7799, with reference to the compound (1). 1-p) was synthesized with reference to the method described in Angewante Chem International Edition, 2011, Vol. 50, pages 9697-9702.

38 g (0.27 mol) of methyl-2-thiophenecarboxylate (Tokyo Chemical Industry Co., Ltd.) and 108 g (1.34 mol) of chloromethyl methyl ether (Tokyo Chemical Industry Co., Ltd.) are stirred at 0 ° C. Then, 125 g (0.48 mol) of tin tetrachloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added over 1 hour, and then stirred at room temperature for 8 hours. After completion of stirring, 100 ml of water was slowly added at 0 ° C., and extracted with chloroform three times. The organic layer was washed with saturated brine, the solvent was dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The obtained brown solid was recrystallized from methanol to obtain compound (1-b) as a pale yellow solid (24.8 g, yield 39%). The measurement result of ¹ H-NMR of the compound (1-b) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.71 (s, 1H), 4.79 (s, 1H), 4.59 (s, 1H), 3.88 (s, 3H) ppm.

24.8 g (0.10 mmol) of the above compound (1-b) was dissolved in 1.2 L of methanol (manufactured by Sasaki Chemical Co., Ltd.) and stirred at 60 ° C., and sodium sulfide (Wako Pure Chemical Industries ( 100 ml of a methanol solution of 8.9 g (0.11 mol) was added dropwise over 1 hour and further stirred at 60 ° C. for 4 hours. After completion of the reaction, the solvent was removed under reduced pressure, 200 ml of chloroform and 200 ml of water were added, and insoluble matters were filtered off. The organic layer was washed twice with water and once with saturated brine, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography (eluent, chloroform) to give compound (1-c) as a white solid (9.8 g, yield 48%). The measurement result of ¹ H-NMR of the compound (1-c) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.48 (s, 1H), 4.19 (t, J = 3.0 Hz, 2H), 4.05 (t, J = 3.0 Hz, 2H), 3.87 (s, 3H) ppm.

To 9.8 g (49 mmol) of the above compound (1-c), 100 ml of water and 30 ml of 3M aqueous sodium hydroxide solution were added, followed by heating and stirring at 80 ° C. for 4 hours. After completion of the reaction, 15 ml of concentrated hydrochloric acid was added at 0 ° C., and the precipitated solid was collected by filtration and washed several times with water. The obtained solid was dried to obtain compound (1-d) as a white solid (8.9 g, yield 98%).
¹ H-NMR (270 MHz, DMSO-d ₆ ): 7.46 (s, 1H), 4.18 (t, J = 3.2 Hz, 2H), 4.01 (t, J = 3.2 Hz, 2H) ) Ppm.

1.46 g (7.8 mmol) of the above compound (1-d) was dissolved in 60 ml of dehydrated tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) and stirred at −78 ° C. to obtain a normal butyl lithium hexane solution ( 1.6 M, 10.7 ml (17.2 mmol) manufactured by Wako Pure Chemical Industries, Ltd. was added dropwise, and the mixture was stirred at -78 ° C for 1 hour. Subsequently, 20 ml of a dry tetrahydrofuran solution of 3.19 g (10.1 mmol) of N-fluorobenzenesulfonimide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise at −78 ° C. over 10 minutes, followed by stirring at room temperature for 12 hours. After completion of the reaction, 50 ml of water was slowly added. 3M Hydrochloric acid was added to acidify the aqueous layer, and the mixture was extracted 3 times with chloroform. The organic layer was dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. By-product was removed by silica gel column chromatography (eluent, ethyl acetate) and then recrystallized from ethyl acetate to obtain compound (1-e) as a pale yellow powder (980 mg, 61% yield). The measurement result of ¹ H-NMR of the compound (1-e) is shown below.
¹ H-NMR (270 MHz, DMSO-d ₆ ): 13.31 (brs, 1H), 4.20 (t, J = 3.0 Hz, 2H), 4.03 (t, J = 3.0 Hz, 2H) ) Ppm.

  To 15 ml of a dehydrated dichloromethane (Wako Pure Chemical Industries, Ltd.) solution of 1.5 g (7.8 mmol) of the above compound (1-e), 2 ml of oxalyl chloride (Tokyo Chemical Industry Co., Ltd.) and then dimethylformamide (Japanese) 1 drop (manufactured by Kojun Pharmaceutical Co., Ltd.) was added and stirred at room temperature for 3 hours. The solvent and excess oxalyl chloride were removed under reduced pressure to obtain compound (1-f) as a yellow oil. Compound (1-f) was used in the next reaction as it was.

  10 ml of a dichloromethane solution of the above compound (1-f, crude product) was 2.6 g (20 mmol) of 2-ethylhexanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 1 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd.) ( 10 mmol) in dichloromethane (15 ml) at room temperature and stirred for 6 hours at room temperature. The reaction solution was washed twice with 1M hydrochloric acid, once with water and once with saturated brine, dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The solution was passed through a short silica gel column (eluent, chloroform) and the solvent was distilled off under reduced pressure to obtain compound (1-g) as a pale yellow oil (crudely purified product). The compound (1-g) was used in the next reaction as it was.

To 60 ml of an ethyl acetate solution of the above compound (1-g, crude product), 20 ml of an ethyl acetate solution of 1.37 g (7.8 mmol) of metachlorobenzoic acid (manufactured by Nacalai Tesque) was added dropwise at 0 ° C. For 5 hours. After removing the solvent under reduced pressure, 30 ml of acetic anhydride was added, and the mixture was heated to reflux for 3 hours. The solvent was removed again under reduced pressure, and the residue was purified by silica gel column chromatography (eluent, dichloromethane: hexane = 1: 1) to give compound (1-h) as a pale yellow oil (1.30 g). The measurement result of ¹ H-NMR of the compound (1-h) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.66 (s, 1H), 7.28 (s, 1H), 4.23 (d, J = 5.9 Hz, 2H), 1.61 (m, 1H), 1.5-1.2 (m, 8H), 0.9 (m, 6H) ppm.

To 20 ml of a dimethylformamide solution of 1.0 g (3.2 mmol) of the above compound (1-h), 1.25 g (7.0 mmol) of N-bromosuccinimide (manufactured by Wako Pure Chemical Industries, Ltd.) is added at room temperature. Stir for hours at room temperature. After completion of the reaction, 80 ml of ethyl acetate was added, the organic layer was washed 5 times with water and once with saturated brine, dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. Purification by silica gel column chromatography (eluent, chloroform: hexane = 1: 3) gave compound (1-i) as a pale yellow oil (1.1 g, yield 73%). The measurement result of ¹ H-NMR of compound (1-i) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 4.25 (d, J = 5.7 Hz, 2H), 1.69 (s, 1H), 1.5-1.2 (m, 6H),. 94 (t, J = 6.8 Hz, 3H), 0.91 (t, J = 6.8 Hz, 3H) ppm.

To 300 ml of dichloromethane solution of 110 g (1.5 mol) of diethylamine (manufactured by Wako Pure Chemical Industries, Ltd.), 100 g (0.68 mol) of 3-thiophenecarbonyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) at 0 ° C. for 1 hour. And stirred at room temperature for 3 hours. After completion of the stirring, 200 ml of water was added, and the organic layer was washed three times with water and once with a saturated saline solution. After drying over anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure. The residue was distilled under reduced pressure to obtain compound (1-k) as a pale orange liquid (102 g, yield 82%). The measurement result of ¹ H-NMR of the compound (1-k) is shown below.

¹ H-NMR (270 MHz, CDCl ₃ ): 7.47 (dd, J = 3.2 Hz and 1.0 Hz, 1H), 7.32 (dd, J = 5.0 Hz and 3.2 Hz, 1H), 7 .19 (dd, J = 5.0 Hz and 1.0 Hz, 1H), 3.43 (brs, 4H), 1.20 (t, J = 6.5 Hz, 6H) ppm.

In 400 ml of dehydrated tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) solution of 73.3 g (0.40 mol) of the above compound (1-k), normal butyl lithium hexane solution (1.6M, manufactured by Wako Pure Chemical Industries, Ltd.) ) 250 ml (0.40 mol) was added dropwise at 0 ° C. over 30 minutes. After completion of dropping, the mixture was stirred at room temperature for 4 hours. After stirring, 100 ml of water was slowly added and stirred for a while, and then the reaction mixture was poured into 800 ml of water. The precipitated solid was collected by filtration and washed with water, methanol, and hexane in this order to obtain compound (1-l) as a yellow solid (23.8 g, yield 27%). The measurement result of ¹ H-NMR of the compound (1-l) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.69 (d, J = 4.9 Hz, 2H), 7.64 (d, J = 4.9 Hz, 2H) ppm.

To 400 ml of dehydrated tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) solution of 42 g (0.50 mol) of thiophene, 250 ml (0.40 mol) of normal butyl lithium hexane solution (1.6 M, manufactured by Wako Pure Chemical Industries, Ltd.) was added. The solution was added dropwise at −78 ° C. over 30 minutes. The reaction mixture was stirred at -78 ° C for 1 hour, and then 76.4 g (0.40 mol) of 2-ethylhexyl bromide (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise at -78 ° C over 15 minutes. The reaction solution was stirred at room temperature for 30 minutes and then heated and stirred at 60 ° C. for 6 hours. After completion of the stirring, the reaction solution was cooled to room temperature, and 200 ml of water and 200 ml of ether were added. The organic layer was washed twice with water and saturated brine, and then dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was distilled under reduced pressure to obtain compound (1-n) as a colorless liquid (28.3 g, 36%). The measurement result of ¹ H-NMR of the compound (1-n) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.11 (d, 4.9 Hz, 1 H), 6.92 (dd, 4.9 Hz and 3.2 Hz, 1 H), 6.76 (d, J = 3 .2 Hz, 1H), 2.76 (d, J = 6.8 Hz, 2H), 1.62 (m, 1H), 1.4-1.3 (m, 8H), 0.88 (m, 6H) ) Ppm.

To 400 ml of dehydrated tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) solution of 17.5 g (89 mmol) of the above compound (1-n), 57 ml of normal butyl lithium hexane solution (1.6 M, manufactured by Wako Pure Chemical Industries, Ltd.) (89 mmol) was added dropwise at 0 ° C. over 30 minutes. The reaction solution was stirred at 50 ° C. for 1 hour, and then 4.9 g (22 mmol) of the above compound (1-1) was added at 50 ° C. and stirred as it was for 1 hour. After completion of the stirring, the reaction solution was cooled to 0 ° C., and a solution of 39.2 g (175 mmol) of tin chloride dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) in 80 ml of 10% hydrochloric acid was added. Stir for hours. After completion of the stirring, 200 ml of water and 200 ml of diethyl ether were added, and the organic layer was washed twice with water and then with a saturated saline solution. After drying over anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure. Purification by silica gel column chromatography (eluent, hexane) gave compound (1-o) as a yellow oil (7.7 g, yield 59%). The measurement result of ¹ H-NMR of the compound (1-o) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.63 (d, J = 5.7 Hz, 1H), 7.45 (d, J = 5.7 Hz, 1H), 7.29 (d, J = 3 .6 Hz, 1H), 6.88 (d, J = 3.6 Hz, 1H), 2.86 (d, J = 7.0 Hz, 2H), 1.70-1.61 (m, 1H), 1 .56-1.41 (m, 8H), 0.97-0.89 (m, 6H) ppm.

To 25 ml of dehydrated tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) solution of 870 mg (1.5 mmol) of the above compound (1-o), normal butyl lithium hexane solution (1.6M, manufactured by Wako Pure Chemical Industries, Ltd.) 2 0.0 ml (3.3 mmol) was added at −78 ° C. using a syringe, and the mixture was stirred at −78 ° C. for 30 minutes and at room temperature for 30 minutes. After cooling the reaction mixture to −78 ° C., 800 mg (4.0 mmol) of trimethyltin chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added at once at −78 ° C., and the mixture was stirred at room temperature for 4 hours. After completion of the stirring, 50 ml of diethyl ether and 50 ml of water were added and stirred at room temperature for 5 minutes, and then the organic layer was washed twice with water and then with a saturated saline solution. After drying the solvent with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure. The obtained orange oil was recrystallized from ethanol to obtain the compound (1-p) as a pale yellow solid (710 mg, yield 52%). The measurement result of ¹ H-NMR of the compound (1-p) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.68 (s, 2H), 7.31 (d, J = 3.2 Hz, 2H), 6.90 (d, J = 3.2 Hz, 2H), 2.87 (d, J = 6.2 Hz, 4H), 1.69 (m, 2H), 1.40-1.30 (m, 16H), 1.0-0.9 (m, 12H), 0.39 (s, 18H) ppm.

  Compound (1-i) 71 mg (0.15 mmol) and compound (1-p) 136 mg (0.15 mmol) in toluene (manufactured by Wako Pure Chemical Industries, Ltd.) 4 ml and dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd.) ) 5 mg of tetrakistriphenylphosphine palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the solution dissolved in 1 ml, and the mixture was stirred at 100 ° C. for 15 hours in a nitrogen atmosphere. Next, 15 mg of bromobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at 100 ° C. for 1 hour. Subsequently, 40 mg of tributyl (2-thienyl) tin (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 100 ° C. for 1 hour. After completion of the stirring, the reaction mixture was cooled to room temperature and poured into 100 ml of methanol. The precipitated solid was collected by filtration and washed with methanol, water, and acetone in this order. Subsequently, it wash | cleaned in order of acetone and hexane using the Soxhlet extractor. Next, the obtained solid was dissolved in chloroform, passed through Celite (manufactured by Nacalai Tesque), and then a silica gel column (eluent, chloroform), and then the solvent was distilled off under reduced pressure. The obtained solid was dissolved again in chloroform and then reprecipitated in methanol to obtain Compound A-1 (91 mg). The weight average molecular weight was 29,000 and the number average molecular weight was 17,000. The light absorption edge wavelength was 778 nm, the band gap (Eg) was 1.59 eV, and the highest occupied molecular orbital (HOMO) level was -5.05 eV.

Synthesis example 2
Compound B-1 was synthesized by the method shown in Scheme 2. The compound (2-b) described in Synthesis Example 2 was synthesized with reference to the method described in Journal of the American Chemical Society, 2009, Vol. 131, pages 7792-7799. .

To 8.4 g (38 mmol) of compound (1-1), 30 ml of ethanol, 120 ml of 20% aqueous sodium hydroxide solution and 5.3 g (80 mmol) of zinc powder (manufactured by Wako Pure Chemical Industries, Ltd.) were added, and the reaction mixture was added for 1 hour. Heated to reflux. 25.0 g (0.11 mol) of 2-ethylhexyl bromide (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further heated to reflux for 4 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and 100 ml of water and 100 ml of chloroform were added. The reaction mixture was filtered through celite, and then the aqueous layer was extracted twice with chloroform. The organic layer was washed twice with water and once with saturated brine, then dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. Purification by silica gel column chromatography (eluent, chloroform: hexane = 1: 5) gave compound (2-a) as a pale yellow oil (4.4 g, yield 26%). The measurement result of ¹ H-NMR of the compound (2-a) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.47 (d, J = 5.7 Hz, 2H), 7.36 (d, J = 5.7 Hz, 2H), 4.18 (d, J = 5 .1 Hz, 4H), 1.9-0.8 (m, 34H) ppm.

To 50 ml of a dehydrated tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) solution of 1.47 g (3.3 mmol) of the above compound (2-a), a normal butyl lithium hexane solution (1.6 M, manufactured by Wako Pure Chemical Industries, Ltd.). ) 13.2 ml (8.3 mmol) was added dropwise at -78 ° C. The reaction solution was stirred at −78 ° C. for 30 minutes and at room temperature for 30 minutes, and then 2.0 g (10 mol) of trimethyltin chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added at −78 ° C. The reaction solution was stirred at room temperature for 6 hours, 80 ml of hexane and 20 ml of water were added, and the organic layer was washed with water three times. After drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure. Recrystallization from isopropanol gave compound (2-b) as a white solid (1.60 g, yield 63%). The measurement result of ¹ H-NMR of the compound (2-b) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.51 (s, 2H), 4.19 (d, J = 5.1 Hz, 4H), 1.8-1.4 (m, 22H), 1. 03 (t, J = 7.3 Hz, 6H), 0.94 (t, J = 7.3 Hz, 6H), 0.44 (s, 18H) ppm.

  Compound (1-i) 71 mg (0.15 mmol) and compound (2-b) 116 mg (0.15 mmol) in toluene (manufactured by Wako Pure Chemical Industries, Ltd.) 4 ml and dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd.) ) 5 mg of tetrakistriphenylphosphine palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the solution dissolved in 1 ml, and the mixture was stirred at 100 ° C. for 15 hours in a nitrogen atmosphere. Next, 15 mg of bromobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at 100 ° C. for 1 hour. Subsequently, 40 mg of tributyl (2-thienyl) tin (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 100 ° C. for 1 hour. After completion of the stirring, the reaction mixture was cooled to room temperature and poured into 100 ml of methanol. The precipitated solid was collected by filtration and washed with methanol, water, and acetone in this order. Subsequently, it wash | cleaned in order of acetone and hexane using the Soxhlet extractor. Next, the obtained solid was dissolved in chloroform, passed through Celite (manufactured by Nacalai Tesque), and then a silica gel column (eluent, chloroform), and then the solvent was distilled off under reduced pressure. The obtained solid was dissolved again in chloroform and then reprecipitated in methanol to obtain Compound B-1 (73 mg). The weight average molecular weight was 31,000 and the number average molecular weight was 13,000. The light absorption edge wavelength was 754 nm, the band gap (Eg) was 1.64 eV, and the highest occupied molecular orbital (HOMO) level was −5.09 eV.

Synthesis example 3
Compound B-2 was synthesized by the method shown in Scheme 3. Compound (3-c) described in Synthesis Example 3 was synthesized with reference to the method described in Journal of the American Chemical Society, 2009, Vol. 131, pages 7792-7799. .

  To 10 ml of a dehydrated dichloromethane (manufactured by Wako Pure Chemical Industries, Ltd.) solution of 800 mg (3.9 mmol) of the above compound (1-e), 1 ml of oxalyl chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), and then dimethylformamide (Wako Pure Chemical Industries, Ltd.) 1 drop of Kogyo Co., Ltd. was added and stirred at room temperature for 3 hours. The solvent and excess oxalyl chloride were removed under reduced pressure to obtain compound (1-f) as a yellow oil. Compound (1-f) was used in the next reaction as it was.

10 ml of a dichloromethane solution of the above compound (1-f, roughly purified product) 1.3 g (10 mmol) of 1-octanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 800 mg (8 mmol) of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd.) ) In dichloromethane (15 ml) at room temperature and stirred for 6 hours at room temperature. The reaction solution was washed twice with 1M hydrochloric acid, once with water and once with saturated brine, dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. Purification by silica gel column chromatography (eluent, chloroform) gave compound (3-a) as a pale yellow solid (1.12 g, yield 90%). The measurement result of ¹ H-NMR of the compound (3-a) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 4.27 (t, J = 6.7 Hz, 2H), 4.16 (t, J = 3.0 Hz, 2H), 4.01 (t, J = 3) 0.0 Hz, 2H), 1.72 (m, 2H), 1.5-1.3 (m, 12H), 0.88 (t, J = 7.0 Hz, 3H) ppm.

To 40 ml of an ethyl acetate solution of 1.1 g (3.5 mmol) of the above compound (3-a), 10 ml of an ethyl acetate solution of 630 mg (3.6 mmol) of metachlorobenzoic acid (manufactured by Nacalai Tesque) was added dropwise at 0 ° C. And stirred at room temperature for 5 hours. After removing the solvent under reduced pressure, 30 ml of acetic anhydride was added, and the mixture was heated to reflux for 3 hours. The solvent was removed again under reduced pressure, and then purified by silica gel column chromatography (eluent, dichloromethane: hexane = 1: 1) to obtain compound (3-b) as a pale yellow oil (1.03 g, yield 94%). It was. The measurement result of ¹ H-NMR of the compound (3-b) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 7.65 (d, J = 2.7 Hz, 1H), 7.28 (dd, J = 2.7 Hz and 5.4 Hz, 1H), 4.31 (t , J = 6.8 Hz, 2H), 1.75 (m, 2H), 1.42-1.29 (m, 12H), 0.89 (t, J = 6.8 Hz, 3H) ppm.

To 20 ml of a dimethylformamide solution of 1.0 g (3.2 mmol) of the above compound (3-b), 1.25 g (7.0 mmol) of N-bromosuccinimide (manufactured by Wako Pure Chemical Industries, Ltd.) is added at room temperature. Stir for hours at room temperature. After completion of the reaction, 80 ml of ethyl acetate was added, the organic layer was washed 5 times with water and once with saturated brine, dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. Purification by silica gel column chromatography (eluent, chloroform: hexane = 1: 3) gave compound (3-c) as a pale yellow solid (1.2 g, yield 79%). The measurement result of ¹ H-NMR of compound (3-c) is shown below.
¹ H-NMR (270 MHz, CDCl ₃ ): 4.32 (t, J = 6.5 Hz, 2H), 1.75 (m, 2H), 1.42-1.29 (m, 12H), 0. 89 (t, J = 6.8 Hz, 3H) ppm.

  Compound (3-c) 71 mg (0.15 mmol) and compound (2-b) 116 mg (0.15 mmol) 4 ml of toluene (manufactured by Wako Pure Chemical Industries, Ltd.) and dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd.) ) 5 mg of tetrakistriphenylphosphine palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the solution dissolved in 1 ml, and the mixture was stirred at 100 ° C. for 15 hours in a nitrogen atmosphere. Next, 15 mg of bromobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at 100 ° C. for 1 hour. Subsequently, 40 mg of tributyl (2-thienyl) tin (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 100 ° C. for 1 hour. After completion of the stirring, the reaction mixture was cooled to room temperature and poured into 100 ml of methanol. The precipitated solid was collected by filtration and washed with methanol, water, and acetone in this order. Subsequently, it wash | cleaned in order of acetone and hexane using the Soxhlet extractor. Next, the obtained solid was dissolved in chloroform, passed through Celite (manufactured by Nacalai Tesque), and then a silica gel column (eluent, chloroform), and then the solvent was distilled off under reduced pressure. The obtained solid was dissolved again in chloroform and then reprecipitated in methanol to obtain Compound B-2 (82 mg). The weight average molecular weight was 22,000 and the number average molecular weight was 11,000. The light absorption edge wavelength was 755 nm, the band gap (Eg) was 1.64 eV, and the highest occupied molecular orbital (HOMO) level was -5.06 eV.

Synthesis example 4
Compound B-3 was synthesized by the method shown in Scheme 4. The compound (4-a) described in Synthesis Example 4 was synthesized with reference to the method described in Journal of the American Chemical Society, 2009, Vol. 131, pages 7792-7799. .

  Compound (4-a) 68 mg (0.15 mmol) and compound (1-p) 136 mg (0.15 mmol) 4 ml of toluene (manufactured by Wako Pure Chemical Industries, Ltd.) and dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd.) ) 5 mg of tetrakistriphenylphosphine palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the solution dissolved in 1 ml, and the mixture was stirred at 100 ° C. for 15 hours in a nitrogen atmosphere. Next, 15 mg of bromobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at 100 ° C. for 1 hour. Subsequently, 40 mg of tributyl (2-thienyl) tin (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 100 ° C. for 1 hour. After completion of the stirring, the reaction mixture was cooled to room temperature and poured into 100 ml of methanol. The precipitated solid was collected by filtration and washed with methanol, water, and acetone in this order. Subsequently, it wash | cleaned in order of acetone and hexane using the Soxhlet extractor. Next, the obtained solid was dissolved in chloroform, passed through Celite (manufactured by Nacalai Tesque), and then a silica gel column (eluent, chloroform), and then the solvent was distilled off under reduced pressure. The obtained solid was dissolved again in chloroform and then reprecipitated in methanol to obtain Compound B-3 (80 mg). The weight average molecular weight was 35,000 and the number average molecular weight was 17,000. The light absorption edge wavelength was 784 nm, the band gap (Eg) was 1.58 eV, and the highest occupied molecular orbital (HOMO) level was -4.91 eV.

Synthesis example 5
Compound B-4 was synthesized by the method shown in Scheme 5. The compound (5-a) described in Synthesis Example 5 was synthesized with reference to the method described in Journal of the American Chemical Society, 2009, Vol. 131, pages 15586-15587. .

  Compound (5-a) 64 mg (0.15 mmol) and compound (1-p) 136 mg (0.15 mmol), 4 ml of toluene (manufactured by Wako Pure Chemical Industries, Ltd.) and dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd.) ) 5 mg of tetrakistriphenylphosphine palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the solution dissolved in 1 ml, and the mixture was stirred at 100 ° C. for 15 hours in a nitrogen atmosphere. Next, 15 mg of bromobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred at 100 ° C. for 1 hour. Subsequently, 40 mg of tributyl (2-thienyl) tin (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 100 ° C. for 1 hour. After completion of the stirring, the reaction mixture was cooled to room temperature and poured into 100 ml of methanol. The precipitated solid was collected by filtration and washed with methanol, water, and acetone in this order. Subsequently, it wash | cleaned in order of acetone and hexane using the Soxhlet extractor. Next, the obtained solid was dissolved in chloroform, passed through Celite (manufactured by Nacalai Tesque), and then a silica gel column (eluent, chloroform), and then the solvent was distilled off under reduced pressure. The obtained solid was dissolved again in chloroform and then reprecipitated in methanol to obtain Compound B-4 (73 mg). The weight average molecular weight was 21,000 and the number average molecular weight was 11,000. The light absorption edge wavelength was 785 nm, the band gap (Eg) was 1.58 eV, and the highest occupied molecular orbital (HOMO) level was -4.92 eV.

Example 1
A chloroform solution containing 1 mg of the above (A-1) and 1 mg of PC ₇₀ BM (manufactured by Solenne) in a proportion of 3% volume concentration of 1,8-diiodooctane (manufactured by Wako Pure Chemical Industries, Ltd.) 0 In addition to 20 ml, the container containing the solution was subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner (US-2 (trade name) manufactured by Iuchi Seieido Co., Ltd., output 120 W) to prepare solution A (donor acceptor). Weight ratio = 1: 1) was obtained. Further, 1 mg of (A-1) and 1.5 mg of PC ₇₀ BM (manufactured by Solenne) were added to a chloroform solution (3% volume concentration) of 0.25 ml of 1,8-diiodooctane (manufactured by Wako Pure Chemical Industries, Ltd.). Solution B (donor acceptor weight) by irradiating ultrasonically in an ultrasonic cleaner (US-2 (trade name) manufactured by Inoue Seieido Co., Ltd., output 120 W) for 30 minutes. Ratio = 1: 1.5).

  A glass substrate having an ITO transparent conductive layer of 125 nm deposited as a positive electrode deposited by sputtering was cut into 38 mm × 46 mm, and then ITO was patterned into a 38 mm × 13 mm rectangular shape by photolithography. The obtained substrate was subjected to ultrasonic cleaning for 10 minutes with an alkali cleaning solution (“Semico Clean” EL56 (trade name), manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water.

After this substrate was UV / ozone treated for 30 minutes, a PEDOT: PSS aqueous solution (0.8% by weight of PEDOT, 0.5% by weight of PPS) serving as a hole transport layer was formed on the substrate to a thickness of 60 nm by spin coating. did. After heating and drying at 200 ° C. for 5 minutes using a hot plate, the above solution A or solution B was dropped onto the PEDOT: PSS layer, and an organic semiconductor layer having a thickness of 130 nm was formed by spin coating. Thereafter, the substrate on which the organic semiconductor layer is formed and the cathode mask are placed in a vacuum deposition apparatus, and the vacuum in the apparatus is evacuated again to 1 × 10 ⁻³ Pa or less. A lithium fluoride layer was deposited to a thickness of 0.1 nm. Then, the aluminum layer used as a negative electrode was vapor-deposited with the thickness of 80 nm. As described above, a photovoltaic device having an area where the stripe-shaped ITO layer and the aluminum layer intersect each other was 2 mm × 2 mm was produced.

The positive and negative electrodes of the photovoltaic device thus fabricated were connected to a Keithley 2400 series source meter and simulated sunlight (OTENTO-SUNIII, manufactured by Spectrometer Co., Ltd., spectral shape) from the ITO layer side in the atmosphere. : AM1.5, intensity: 100 mW / cm ² ), and the current value was measured when the applied voltage was changed from −1V to + 2V. For the photovoltaic device using the solution A (donor acceptor weight ratio = 1: 1), the short-circuit current density at this time (current density value when the applied voltage is 0 V) is 15.50 A / cm ² , open circuit The voltage (value of the applied voltage when the current density was 0) was 0.79 V, the fill factor (FF) was 0.66, and the photoelectric conversion efficiency calculated from these values was 8.06%. The voltage-current density curve at this time is shown in FIG. The horizontal axis is voltage, and the vertical axis is current density. Further, for the photovoltaic device using the solution B (donor acceptor weight ratio = 1: 1.5), the short-circuit current density is 15.13 A / cm ² , the open circuit voltage is 0.78 V, and the fill factor (FF) is The photoelectric conversion efficiency calculated from these values was 7.31%.

The fill factor and photoelectric conversion efficiency were calculated by the following equations.
Fill factor = IVmax (mA · V / cm ² ) / (Short-circuit current density (mA / cm ² ) × Open circuit voltage (V))
(Here, IVmax is the value of the product of the current density and the applied voltage at the point where the product of the current density and the applied voltage becomes maximum when the applied voltage is between 0 V and the open circuit voltage value.)
Photoelectric conversion efficiency = [(short circuit current density (mA / cm ² ) × open voltage (V) × fill factor) / pseudo sunlight intensity (100 mW / cm ² )] × 100 (%)
The fill factor and photoelectric conversion efficiency in the following examples and comparative examples were all calculated by the above formula.

Comparative Example 1
A photovoltaic device was produced in the same manner as in Example 1 except that B-1 was used instead of A-1, and current-voltage characteristics were measured. The short-circuit current density of the device using a solution with a donor-acceptor weight ratio of 1: 1 is 11.20 mA / cm ² , the open-circuit voltage is 0.74 V, and the fill factor (FF) is 0.59. The calculated photoelectric conversion efficiency was 4.89%. Moreover, the short circuit current density of the element using the solution whose donor-acceptor weight ratio is 1: 1.5 is 12.74 mA / cm ² , the open circuit voltage is 0.74 V, and the fill factor (FF) is 0.66. The photoelectric conversion efficiency calculated from these values was 6.39%.

Comparative Example 2
A photovoltaic device was produced in the same manner as in Example 1 except that B-2 was used instead of A-1, and current-voltage characteristics were measured. The short-circuit current density of the device using a solution with a donor-acceptor weight ratio of 1: 1 is 11.44 mA / cm ² , the open-circuit voltage is 0.74 V, and the fill factor (FF) is 0.62. The calculated photoelectric conversion efficiency was 5.25%. Moreover, the short circuit current density of the element using the solution whose donor acceptor weight ratio is 1: 1.5 is 11.22 mA / cm ² , the open circuit voltage is 0.74 V, and the fill factor (FF) is 0.60. The photoelectric conversion efficiency calculated from these values was 4.98%.

Comparative Example 3
A photovoltaic device was produced in the same manner as in Example 1 except that B-3 was used in place of A-1, and current-voltage characteristics were measured. The short-circuit current density of the device using the solution having a donor-acceptor weight ratio of 1: 1 is 11.19 mA / cm ² , the open-circuit voltage is 0.68 V, and the fill factor (FF) is 0.57. The calculated photoelectric conversion efficiency was 4.34%. Moreover, the short circuit current density of the element using the solution whose donor-acceptor weight ratio is 1: 1.5 is 12.56 mA / cm ² , the open circuit voltage is 0.68 V, and the fill factor (FF) is 0.55. The photoelectric conversion efficiency calculated from the value was 4.70%.

Comparative Example 4
A photovoltaic device was produced in the same manner as in Example 1 except that B-4 was used instead of A-1, and current-voltage characteristics were measured. The short-circuit current density of the device using the solution having a donor-acceptor weight ratio of 1: 1 is 13.51 mA / cm ² , the open-circuit voltage is 0.74 V, and the fill factor (FF) is 0.59. The calculated photoelectric conversion efficiency was 5.90%. Moreover, the short circuit current density of the element using the solution whose donor-acceptor weight ratio is 1: 1.5 is 15.02 mA / cm ² , the open circuit voltage is 0.74 V, and the fill factor (FF) is 0.61. The photoelectric conversion efficiency calculated from these values was 6.78%.

  As is clear from Table 1, the photovoltaic device (Example 1) produced using the electron donating organic material having the structure represented by the general formula (1) was obtained by using other light produced under the same conditions. High photoelectric conversion efficiency was shown compared with the electromotive force element (Comparative Examples 1-4).

1: Substrate 2: Positive electrode 3: Organic semiconductor layer 4: Negative electrode 5: Layer having an electron-donating organic material 6: Layer having an electron-accepting organic material

Claims (6)

A conjugated polymer having a structure represented by the general formula (1).

(In the general formula (1), R ¹ represents an optionally substituted alkoxycarbonyl group or alkanoyl group. R ² may be the same or different and may be substituted heteroaryl groups. N represents the degree of polymerization and represents an integer of 2 to 1,000.) An electron-donating organic material using the conjugated polymer according to claim 1. A photovoltaic element material comprising the electron donating organic material and the electron accepting organic material according to claim 2. The photovoltaic element material according to claim 3, wherein the electron-accepting organic material is a fullerene compound. The photovoltaic element material according to claim 4, wherein the fullerene compound contains a C ₇₀ derivative. A photovoltaic device having at least a positive electrode and a negative electrode, wherein the photovoltaic device has an organic semiconductor layer containing the material for a photovoltaic device according to any one of claims 3 to 5 between the negative electrode and the positive electrode.

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