JP6736077B2 - Novel squarylium derivative and organic thin-film solar cell using the same - Google Patents

Description

The present invention relates to a novel squarylium derivative and an organic thin film solar cell device using the same.

In recent years, organic thin-film solar cells have been characterized by being lightweight and freely bendable, and are also advantageous in terms of manufacturing cost. Therefore, they are entering the stage of practical application and market introduction in place of silicon-based inorganic solar cells. The organic thin film solar cell includes a vapor deposition type and a coating type. In particular, the coating type organic thin film solar cell has a lower manufacturing cost than the vapor deposition type organic thin film solar cell and is suitable for mass production. However, the organic thin-film solar cell has a photoelectric energy conversion efficiency of about 10%, and there is still room for improvement in efficiency and reliability in comparison with silicon-based inorganic solar cells, and active research and development is underway. It is being appreciated.

Sunlight has 50% or more of its energy in the near infrared/infrared region having a wavelength longer than 650 nm. Therefore, in order to dramatically improve the photoelectric conversion efficiency, it is essential to efficiently absorb this wavelength region and extract it as electric energy. The organic thin film solar cell element is manufactured using a donor material and an acceptor material. Fullerene derivatives, which are generally used as acceptor materials, have the advantages of slow reverse electron transfer and high symmetry, but they do not have strong absorption in the near-infrared region, which improves the efficiency of organic thin-film solar cells. For this reason, development of a donor material having absorption in a long wavelength region is very important. Further, the relationship between the energy levels of the donor material and the acceptor material is important for improving the efficiency of the organic thin film solar cell. In order to transfer charges from excitons (excitons) generated by absorbing sunlight by a donor material to an acceptor material, generally, the lowest unoccupied molecular orbital (LUMO) level of the donor material is the LUMO of the acceptor material. It is said that it is preferable to be shallower than the level by 0.3 eV or more. In the coating type organic thin film solar cell, phenyl C71 methyl butyrate (PC ₇₀ BM), which is usually highly soluble, is used as an acceptor material. Since the LUMO level of PC ₇₀ BM is 4.0 eV, the LUMO level of about 3.7 eV is required for the donor material.

The donor material used in the coated organic thin-film solar cell must, of course, be well soluble in the solvent. The donor materials are roughly classified into two types, a high molecular type and a low molecular type. Although the conversion efficiency of polymer type materials has improved to about 8%, it is difficult to purify and to improve the purification efficiency of polymer type materials, and the characteristic changes between manufacturing lots are large and quality can be maintained. difficult. On the other hand, the low molecular weight material has a characteristic that it does not have a molecular weight distribution, is easy to purify and is highly reliable, or that the quality between manufacturing lots does not change, and the energy conversion efficiency is not affected depending on the lot. However, the low molecular weight material has a low mobility of about 10 ⁻⁵ cm ² /Vs at the present time and an energy conversion efficiency of 7% or less. In addition, among low molecular weight materials, materials that have achieved high efficiency generally have low solubility, and when producing a coating type organic thin film solar cell, halogen-based materials such as orthodichlorobenzene (ODCB) and chloroform are used. A solvent must be used, which is an environmental problem. Therefore, in order to improve the performance and practicality of coating-type organic thin-film solar cells, a new low-molecular material that has high absorption capacity for near-infrared light and high mobility and shows high solubility in non-halogen solvents, etc. Development is required.

The squarylium derivative has a high solubility even in a non-halogen solvent, has a strong absorption in the near infrared region, has a slow reverse electron transfer, and has a high symmetry structure. Research and development has been carried out, and many reports have already been made (Non-patent documents 1 to 3).

G. Chen, H. Sasabe, Y. Sasaki, H. Katagiri, X.F. Wang, T. Sano, Z. Hong, Y. Yang, and J. Kido, “Chem.Mater.” 2014, 26, 1356-1364. Sasaki, Sasabe, Hong, Yang, and Kido, 62nd Annual Meeting of the Polymer Society of Japan, 1J28 (2013) H. Sasabe, T. Igarashi, Y. Sasaki. G. Chen, Z. Hong, and J. Kido, “RSC Advances” 2014,4, 42804-42807.

The squarylium derivative can be synthesized relatively easily in a high yield by a dehydration condensation reaction, is environmentally friendly, and can introduce various substituents. Among the squarylium derivatives, SQ-1, YSQ-8, and SQ-BP have a PCH (power conversion efficiency) of 4.0% and 3.8%, respectively, in a BHJ (bulk heterojunction) type element formed by coating film formation. Achieved 4.8%. The energy conversion efficiency of these derivatives is improved compared to the previous ones, but still remains low. In addition, organic thin-film solar cells using these squarylium derivatives have higher V _OC (open circuit voltage) and J _SC (short circuit current density) values than other materials, but have a low FF (fill factor). There was a problem.

Among the above derivatives, YSQ-8 and SQ-BP are molecules designed to have an energy level suitable for combining PC ₇₀ BM as an acceptor material. Among them, SQ-BP has a bilaterally symmetrical molecular structure, the yield of synthesis is 80% or more, and PCE is relatively high at 4.8%.

Therefore, in the present invention, in order to provide a novel squarylium derivative useful for providing a highly efficient device, focusing on SQ-BP, improving the terminal substituents thereof, without changing the energy level, An object is to improve the mobility in a thin film state and further improve FF to improve energy conversion efficiency. Another object is to provide a donor material made of the obtained squarylium derivative and an organic thin-film solar cell using the same.

前記一般式（１）中、Ｒ₁はそれぞれ独立に芳香族基、Ｒ₂はそれぞれ独立に炭素数４以上の分岐した脂肪族炭化水素基である。
前記一般式（１）中、Ｒ₁は炭素数６〜５０の芳香族基であり、Ｒ₂は炭素数４〜２０の脂肪族炭化水素基であることが好ましい。
本発明の有機薄膜太陽電池は、前記スクアリリウム誘導体を用いたものであることを特徴とする。 The present invention comprises the following items.
The present invention is characterized by being a squarylium derivative represented by the following general formula (1).

In the general formula (1), R ₁ is independently an aromatic group, and R ₂ is independently a branched aliphatic hydrocarbon group having 4 or more carbon atoms.
In the general formula (1), R ₁ is preferably an aromatic group having 6 to 50 carbon atoms, and R ₂ is preferably an aliphatic hydrocarbon group having 4 to 20 carbon atoms.
The organic thin-film solar cell of the present invention is characterized by using the squarylium derivative.

The squarylium derivative of the present invention has a deepest occupied molecular orbital (HOMO) by introducing an aromatic group into the amino group in the squarylium derivative, that is, R ₁ in the general formula (1). Therefore, long wavelength light can be absorbed. In addition, the planarity of the molecule becomes high, the face-on orientation becomes high during film formation, and the carrier mobility can be improved. Further, it exhibits strong absorption in the region of 550 to 700 nm.
Further, by introducing a branched aliphatic hydrocarbon group having 4 or more carbon atoms into R ₂ in the general formula (1), the solubility in a non-halogen solvent is improved.

Therefore, according to the present invention, by using the squarylium derivative represented by the general formula (1), the obtained device has improved carrier mobility in a thin film state and improved FF value. A highly efficient organic thin film solar cell with improved energy conversion efficiency can be provided.
Further, the squarylium derivative represented by the general formula (1) can be dehalogenated due to its improved solubility in a non-halogen solvent, which can be expected to solve environmental problems and improve device performance. ..
Further, the squarylium derivative represented by the above general formula (1) can be synthesized in large quantities at high yield and at low cost. Therefore, the squarylium derivative represented by the general formula (1) is extremely important industrially.

It is a schematic sectional drawing which showed typically the element structure of the organic thin-film solar cell of this invention. FIG. 2 shows a) SQ-ET, b) SQ-EP, c) SQ-EN, d) SQ-EB, e) SQ-ETPA, f) SQ-EF, and g) SQ-ES. When measured in a solution state (---), when measured as a cast film (-■-), when measured after thermal annealing treatment (70°C, 10 minutes) (-◆-), thermal annealing treatment (120 It is a figure showing a UV-Vis absorption spectrum at the time of measuring after 10 minutes (°C) (-▲-). FIG. 3 is a diagram showing a relationship between a) voltage-current density and b) wavelength-external quantum efficiency (EQE) of SQ-EP. FIG. 4 is a diagram showing the relationship of a) voltage-current density, b) wavelength-external quantum efficiency (EQE) of SQ-EN. FIG. 5 is a diagram showing the relationship of a) voltage-current density, b) wavelength-external quantum efficiency (EQE) of SQ-EB. FIG. 6 is a diagram showing a) voltage-current density, b) wavelength-external quantum efficiency (EQE) relationship of SQ-ETPA, SQ-EF, and SQ-ES.

Hereinafter, the present invention will be described in detail.
[Squarylium derivative]
The squarylium derivative of the present invention is represented by the following general formula (1).

In the general formula (1), R ₁ is an aromatic group. The aromatic group may be an aromatic hydrocarbon group, or the aromatic group may contain a nitrogen atom, an oxygen atom, a sulfur atom or the like.
The aromatic hydrocarbon group may be a monocyclic aryl group or a polycyclic (fused ring) aromatic hydrocarbon group, and a part of hydrogen atoms on the aromatic ring in the aromatic hydrocarbon group may be, for example, methyl group. It may be substituted with a group, an isopropyl group, an isobutyl group or the like.
Examples of the group containing a nitrogen atom, an oxygen atom, a sulfur atom or the like in the aromatic group include a diphenylaminophenyl group, an ether group and a thioether group, a furanyl group, a thiophenyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group. Group, dibenzothiophenyl group and the like.
The aromatic group is preferably an aromatic group having 6 to 50 carbon atoms. Examples of the aromatic group having 6 to 50 carbon atoms include phenyl group, biphenyl group, naphthyl group, triphenylenyl group, terphenyl group, quarterphenyl group, anthracenyl, 9,9'-spirobifluorenyl group, diphenyl. Examples thereof include an aminophenyl group and a 9,9′-dimethylfluorenyl group. Of these, a phenyl group, a triphenylenyl group, a naphthyl group, a biphenyl group, a terphenyl group, a quarterphenyl group, a 9,9'-spirobifluorenyl group, a diphenylaminophenyl group, and a 9,9'-dimethylfluorene group. More preferably, it is a phenyl group, a 2-triphenylenyl group, a 2-naphthyl group, a biphenyl-4-yl group, a 4-(diphenylamino)phenyl group, a 2-(9,9′-spirobifluorenyl) group. The group, 3-(9,9'-dimethylfluorenyl) group, is particularly preferred.

In the above general formula (1), R ₂ is a branched aliphatic hydrocarbon group having 4 or more carbon atoms, preferably a branched aliphatic hydrocarbon group having 4 to 20 carbon atoms.
Examples of the branched aliphatic hydrocarbon group having 4 to 20 carbon atoms include isobutyl group, 2-ethylhexyl group and 2-ethyloctyl group. Among these, a 2-ethylhexyl group, an isobutyl group, a 2-ethyloctyl group and the like are more preferable, and a 2-ethylhexyl group is particularly preferable.
Here, the aliphatic hydrocarbon group broadly refers to a group other than an aromatic hydrocarbon group, and may be chain (acyclic) or cyclic, and one of the hydrogen atoms constituting the aliphatic hydrocarbon group. The part may be substituted with, for example, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an ether group or the like.
It should be noted that R ₁ and R ₂ have a hydrogen atom partially substituted with a nitrogen atom, a sulfur atom, an oxygen atom, a phosphorus atom or a silicon atom, or a substituent containing these, within a range that does not impair the effects of the present invention. May be.

Specifically, the compound represented by the general formula (1) is a compound represented by the following structural formula: SQ-ET, SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF. , And SQ-ES are preferred.

The squarylium derivative represented by the general formula (1) can have a deep HOMO and a wide absorption in the near-infrared region by having an aromatic hydrocarbon group at one of the terminal substituents, and at the other, By having a branched aliphatic hydrocarbon group, the solubility in an organic solvent is improved, for example, when the terminal substituents of the squarylium derivative are both aromatic groups, or one of the terminal substituents is aromatic. The molar extinction coefficient in the near infrared region and the solubility in an organic solvent are improved as compared with the case where the other is a linear aliphatic group.
Therefore, the squarylium derivative can be suitably used as a donor material for an acceptor material composed of fullerene such as PC ₇₀ BM or a derivative thereof.

[Method for producing squarylium derivative]
The squarylium derivative of the present invention can be produced, for example, by the method shown below. An example of the manufacturing method of SQ-ET is shown.
By reacting 2-ethylhexylamine and 2-bromotriphenylene in a dimethylsulfoxide (DMSO) solution in the presence of copper(I) iodide, potassium carbonate and L-proline, (2-ethyl-1-hexyl) (2-Triphenylyl)amine is obtained. Then, the obtained (2-ethyl-1-hexyl)(2-triphenylylyl)amine and 1-bromo-3,5-dimethoxybenzene were combined with Pd(0) catalyst, potassium-t-butoxide and tributylphosphine. The corresponding amine compound is obtained by heating under reflux in a xylene solution. Then, boron tribromide is added to the obtained amine compound and reacted in a methylene chloride solution to obtain a 3,5-dihydroxyaniline derivative. Then, squaric acid is added to the obtained 3,5-dihydroxyaniline derivative and reacted in a mixed solution of toluene and butanol to obtain SQ-ET with a yield of 80%.
However, the squarylium derivative represented by the general formula (1) is not limited to the above-mentioned method, and can be produced by various known methods.

[Organic thin-film solar cell and manufacturing method thereof]
The organic thin-film solar cell element of the present invention (hereinafter referred to as “solar cell element”) has an element structure in which at least one organic electroluminescence (EL) layer is laminated between a pair of electrodes (anode 2 and cathode 6). However, typically, as shown in FIG. 1, it has a device structure in which a substrate 1, an anode 2, a hole transport layer 3, an active layer 4, an electron transport layer 5 and a cathode 6 are sequentially stacked.
Hereinafter, the structure of the solar cell element of the present invention will be described.

<Structure of solar cell element>
The structure of the solar cell element of the present invention is not limited to the example of FIG. 1, and 1) anode buffer layer (not shown)/hole transport layer/active layer and 2) anode are provided between the anode and the cathode in order. Buffer layer (not shown)/active layer/electron transport layer, 3) anode buffer layer (not shown)/hole transport layer/active layer/electron transport layer, 4) anode buffer layer (not shown)/positive Layer containing hole transporting compound, active compound and electron transporting compound, 5) Anode buffer layer (not shown)/Layer containing hole transporting compound and active compound, 6) Anode buffer layer (not shown)/ Layer containing active compound and electron transporting compound, 7) Anode buffer layer (not shown)/layer containing hole electron transporting compound and active compound, 8) Anode buffer layer (not shown)/Active layer/Positive A configuration in which a hole block layer (not shown)/electron transport layer is provided can be used. Further, although the active layer shown in FIG. 1 is a single layer, it may be two or more layers.

<Anode>
For the anode, a material having a surface resistance of usually 1000 Ω (ohm) or less, preferably 100 Ω or less in a temperature range of −5 to 80° C. is used.
When light is extracted from the anode side of the solar cell element (bottom emission), the anode needs to be transparent to visible light (average transmittance for light of 380 to 680 nm is 50% or more). Indium tin oxide (ITO), indium-zinc oxide (IZO), or the like is used as the material of the anode. Among these, ITO is preferable from the viewpoint of easy availability.
Further, when light is extracted from the cathode side of the device (top emission), the light transmittance of the anode is not limited. Therefore, in addition to ITO and IZO, stainless steel, copper, silver, gold, A simple substance of platinum, tungsten, titanium, tantalum or niobium, or an alloy thereof is used.
The thickness of the anode is usually 2 to 300 nm in the case of bottom emission in order to realize high light transmittance, and is usually 2 nm to 2 mm in the case of top emission.

<Anode buffer layer>
The anode buffer layer is formed by applying a material for an anode buffer layer on the anode and then heating.
In this coating operation, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, dip coating method, spray coating method, screen printing method, flexographic printing method, offset printing method, A known coating method such as an inkjet printing method can be applied.
In addition, as a material for the anode buffer layer, a material having high resistance to an organic solvent is usually used from the viewpoint of preventing the anode buffer layer from being dissolved during formation of the active layer.
The thickness of the anode buffer layer is usually 5 to 50 nm, preferably 10 to 30 nm, from the viewpoint of sufficiently exerting the effect as the buffer layer and preventing an increase in driving voltage of the solar cell element.

<Active layer, hole transport layer, electron transport layer>
The organic EL layer in the solar cell element is composed of an active layer, a hole transport layer and an electron transport layer.
The squarylium derivative represented by the general formula (1) is used for the active layer. The squarylium derivative is usually used by mixing an acceptor material. By using the squarylium derivative as a donor material and forming the active layer 4 together with the acceptor material, a highly efficient organic thin film solar cell can be provided.
A known material is appropriately selected and used as the acceptor material, but a compound having an electron transporting property and a deep HOMO energy level is preferable, and specifically, fullerene (C60, C70, etc.) or a derivative thereof. A body (PC ₇₀ BM or the like) is preferably used.

The active layer may be inserted between the hole transporting layer and the electron transporting layer as shown in FIG. 1 in order to supplement the carrier transporting property of the active layer, or the active layer may contain the acceptor material. At the same time, a hole transporting compound or an electron transporting compound may be dispersed and used.
Examples of the hole transporting compound include metal oxides such as molybdenum (VI) oxide (MoO ₃ ), vanadium oxide (V ₂ O ₅ ), tungsten oxide (WO ₃ ), ruthenium oxide (RuO ₂ ), and hexaaza. Low molecular weight materials such as triphenylene hexacarbonyl (HATCN), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ), and the introduction of polymerizable functional groups into the low molecular weight materials. And the like, which are polymerized.
Examples of the electron transporting compound include phenanthroline derivatives such as BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and B4PyMPM (bis-3,6-(3,5-di-4). -Pyridylphenyl)-2-methylpyrimidine) and other low molecular weight materials such as oligopyridine derivatives and [60]fullerene, [70]fullerene and other nanocarbon derivatives, and by introducing a polymerizable functional group into the low molecular weight material. Examples include polymerized ones.

<Hole blocking layer>
A hole blocking layer may be provided adjacent to the cathode side of the active layer for the purpose of suppressing the passage of holes through the active layer and efficiently recombine with the electrons in the active layer. For the hole blocking layer, a compound having a deeper HOMO level than the active compound is used, and for example, a triazole derivative, an oxadiazole derivative, a phenanthroline derivative, an aluminum complex, or the like is used.
Further, an exciton block layer may be provided adjacent to the cathode side of the active layer for the purpose of preventing excitons (excitons) from being deactivated by the cathode metal. For this exciton block layer, a compound having a triplet excitation energy larger than that of the active compound is used, and as the compound, a triazole derivative, a phenanthroline derivative, an aluminum complex or the like is used.

<Cathode>
As the cathode material, a material having a low work function (4 eV or less) and being chemically stable is used. Specific examples thereof include known cathode materials such as Al, MgAg alloy, and alloys of Al and alkali metals such as AlLi and AlCa. A resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, an ion plating method, or the like is used as a film forming method of these cathode materials. The thickness of the cathode is usually 10 nm to 1 μm, preferably 50 to 500 nm.

Further, for the purpose of lowering the electron injection barrier from the cathode to the organic EL layer to increase the electron injection efficiency, a metal layer having a work function lower than that of the cathode is used as a cathode buffer layer between the cathode and a layer adjacent to the cathode. May be inserted. Examples of low work function metals that can be used for such purposes include alkali metals, alkaline earth metals, and rare earth metals. Further, an alloy or a metal compound may be used as long as it has a work function lower than that of the cathode. As a method for forming these cathode buffer layers, a vapor deposition method, a sputtering method, or the like can be used. The thickness of the cathode buffer layer is usually 0.05 to 50 nm, preferably 0.1 to 20 nm.

Furthermore, the cathode buffer layer can be formed as a mixture of the above-mentioned low work function metal or the like and an electron transporting compound. As a film forming method in this case, a co-evaporation method can be used. Further, in the case where coating with a solution is possible, a film forming method such as a spin coating method, a spray coating method, a dip coating method, or a printing method (inkjet printing method, dispenser coating method) can be used. In this case, the thickness of the cathode buffer layer is usually 0.1 to 100 nm, preferably 0.5 to 50 nm. A layer made of a conductive polymer or a layer made of a metal oxide, a metal fluoride, an organic insulating material, or the like and having an average film thickness of 2 nm or less may be provided between the cathode and the organic layer.

<Substrate>
A material satisfying the mechanical strength required for the solar cell element is used for the substrate forming the element.
For bottom emission type solar cell elements, a substrate transparent to visible light is used. For example, glass such as soda glass and non-alkali glass; acrylic resin, methacrylic resin, polycarbonate resin, polyester resin, nylon resin, etc. Transparent plastic; a substrate made of silicon can be used.
Top emission type solar cell elements include, in addition to the substrate used for bottom emission type solar cell elements, stainless steel, copper, silver, gold, platinum, tungsten, titanium, tantalum or niobium alone or alloys thereof. A substrate such as can be used.
Although the thickness of the substrate depends on the required mechanical strength, it is usually 0.1 to 10 mm, preferably 0.25 to 2 mm.
The film thickness of each layer is generally within the range of 5 nm to 5 μm.

(Method for forming solar cell element)
The organic EL compound layer is formed by, for example, a vapor deposition method (resistance heating vapor deposition method, electron beam vapor deposition method, etc.), a dry process such as a sputtering method, or a coating method (spin coating method, casting method, die coating method, microgravure coating method). , Gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, spray coating method, screen printing method, flexographic printing method, offset printing method, inkjet printing method, etc.) be able to. Among these methods, the spin coating method, die coating method and spray coating method are preferably used.

In order to use the solar cell element stably for a long period of time, it is preferable to attach a protective layer and/or a protective cover around the solar cell element. For the protective layer, polymer compounds, metal oxides, metal fluorides, metal borides, etc. are used. For the protective cover, a glass plate, a plastic plate whose surface has been made to have low water permeability, a metal, or the like is used. It is preferably used. Further, if the space is filled with an inert gas such as nitrogen or argon, the oxidation of the cathode can be prevented. It is possible to suppress giving an image to the battery element.

[Use]
The organic thin-film solar cell of the present invention is suitably used for an image display device as a pixel of a matrix system or a segment system. Further, the organic thin film solar cell is preferably used as a surface emitting light source without forming pixels.
The organic thin film solar cell of the present invention is specifically a display device in a computer, TV, mobile terminal, mobile phone, car navigation, sign, signboard, viewfinder of video camera, backlight, electrophotography, lighting, resist. It is preferably used for a light irradiation device in exposure, a reading device, interior lighting, an optical communication system and the like.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the examples.

¹Ｈ−ＮＭＲ、ＭＳ及び元素分析により、ＳＱ−ＥＴの生成を確認した。
結果を以下に示す。
¹H NMR(400 MHz, CDCl₃): δ 10.97 (s, 4H), 8.74-8.63 (m, 8H), 8.53 (d, 2H, J=7.6 Hz), 8.45 (d,2H J=2.8Hz), 7.73-7.65 (m, 8H), 7.49 (d, 2H, J=9.2 Hz), 5.86 (s,4H), 3.84 (d, 4H, J=7.2 Hz), 1.85-1.78 (m, 2H), 1.42-1.22 (m, 16H),0.88-0.81 (m, 12H) ppm
MS: m/z n.d. [M]⁺
Anal. Calcd for C₆₈H₆₄N₂O₆:C, 81.25; H, 6.42; N, 2.79%. Found: C, 81.25; H, 6.52; N, 2.70%. [Example 1] Synthesis of SQ-ET (i) Synthesis of (2-ethyl-1-hexyl)(2-triphenylylyl)amine 1.55 g (12 mmol) of 2-ethylhexylamine and 2.45 g (8 mmol of 2-bromotriphenylene) ) Was dissolved in 8 ml of dimethyl sulfoxide (DMSO), 228 mg (1.2 mmol) of copper(I) iodide, 2.21 g (16 mmol) of potassium carbonate and 230 mg (2 mmol) of L-proline were added, The mixture was stirred at 90°C for 21 hours, further heated and stirred at 140°C for 18 hours.
The obtained crude product was transferred to a separatory funnel and diluted with 100 ml of ethyl acetate, and 100 ml of ion-exchanged water was added for washing. Next, the same operation was performed twice using a saturated saline solution for washing. Then, it dehydrated using magnesium sulfate and the solvent was removed under reduced pressure. Finally, purification by column chromatography on silica gel (solvent; hexane:toluene = 3:1) gave N-(2-ethylhexyl)triphenylyl-2-amine with a yield of 53%.
(Ii) Synthesis of SQ-ET 1.39 g (6.4 mmol) of 1-bromo-3,5-dimethoxybenzene and 1.52 g (4.29 mmol) of N-(2-ethylhexyl)triphenylyl-2-amine were added to 30 ml of xylene. In a solution of tris(dibenzylideneacetone)dipalladium(0)(Pd ₂ (dba) ₃ ) 36 mg (0.04 mmol), potassium t-butoxide 481 mg (4.3 mmol), tributylphosphine 49 mg( 0.24 mmol) was added and the mixture was heated under reflux for 21 hours to obtain N-(2-ethylhexyl)-N-(3,5-dimethoxyphenyl)triphenylene-2-amine.
A solution of 2.3 g (9.2 mmol) of boron tribromide dissolved in 9.2 ml of methylene chloride was added thereto, and the mixture was stirred at room temperature for 23 hours to give 5-(N-(2-ethylhexyl)-. N-(triphenylenyl)amino)benzene-1,3-diol was obtained.
A solution of 166 mg (1.45 mmol) of squaric acid dissolved in 45 ml of toluene and 15 ml of butanol was added thereto, and the mixture was heated under reflux for 18 hours to obtain SQ-ET with a yield of 102%.

The formation of SQ-ET was confirmed by ¹ H-NMR, MS and elemental analysis.
The results are shown below.
¹ H NMR (400 MHz, CDCl ₃ ): δ 10.97 (s, 4H), 8.74-8.63 (m, 8H), 8.53 (d, 2H, J=7.6 Hz), 8.45 (d,2H J=2.8 Hz) , 7.73-7.65 (m, 8H), 7.49 (d, 2H, J=9.2 Hz), 5.86 (s, 4H), 3.84 (d, 4H, J=7.2 Hz), 1.85-1.78 (m, 2H), 1.42-1.22 (m, 16H), 0.88-0.81 (m, 12H) ppm
MS: m/z nd [M] ⁺
Anal. Calcd for C ₆₈ H ₆₄ N ₂ O ₆ :C, 81.25; H, 6.42; N, 2.79%.Found: C, 81.25; H, 6.52; N, 2.70%.

（ii）ＳＱ−ＥＰの合成
１−ブロモ−３，５−ジメトキシベンゼン３．３６ｇ（１５．５ｍｍｏｌ）及びＮ−（２−エチル−１−ヘキシル）アニリン１．５９ｇ（７．７３ｍｍｏｌ）をキシレン８０ｍｌに溶解させた溶液中に、トリス（ジベンジリデンアセトン）ジパラジウム（０）（Ｐｄ₂（ｄｂａ）₃）９１ｍｇ（０．１ｍｍｏｌ）、カリウム−ｔ−ブトキシド３．７ｍｇ（３３ｍｍｏｌ）、トリブチルホスフィン８２ｍｇ（０．４ｍｍｏｌ）を添加して、２５時間加熱還流することにより、Ｎ−（２−エチルヘキシル）−３，５−ジメトキシ−Ｎ−フェニルベンゼンアミンを得た。
ここに、三臭化ホウ素４．０ｇ（１６ｍｍｏｌ）を塩化メチレン１６ｍｌに溶解させた溶液を添加し、室温で２１時間攪拌することにより、５−（Ｎ−（２−エチルヘキシル）−Ｎ−フェニルアミノ）ベンゼン−１，３−ジオールを得た。
ここに、スクアリン酸１６７ｍｇ（１．４７ｍｍｏｌ）をトルエン４５ｍｌ及びブタノール１５ｍｌに溶解させた溶液を添加し、２４時間加熱還流することにより、収率８３％でＳＱ−ＥＰを得た。

¹Ｈ−ＮＭＲ、ＭＳ及び元素分析により、ＳＱ−ＥＰの生成を確認した。
結果を以下に示す。
¹H NMR(400 MHz, CDCl₃): δ 10.94 (s, 4H), 7.45 (t, 4H, J=7.2 Hz), 7.89 (t, 2H, J=7.2 Hz), 7.18(d, 4H J=7.2 Hz), 5.74 (s, 4H), 3.66 (d, 4H, J=7.2 Hz), 1.73-1.67 (m,2H), 1.43-1.16 (m, 16H), 0.87-0.80 (m, 12H) ppm
MS: m/z 706 [M]⁺
Anal. Calcd for C₄₄H₅₂N₂O₆:C, 74.97; H, 7.44; N, 3.97%. Found: C, 75.04; H, 7.35; N, 3.92%. [Example 2] Synthesis of SQ-EP (i) Synthesis of N-(2-ethylhexyl)benzenamine 5.81 g (45 mmol) of 2-ethylhexylamine and 2.36 g (15 mmol) of bromobenzene were added to 15 ml of dimethyl sulfoxide (DMSO). 571 mg (3 mmol) of copper(I) iodide, 5.52 g (40 mol) of potassium carbonate and 575 mg (5 mmol) of L-proline were added to the solution dissolved in, and the mixture was stirred at 90° C. for 16 hours, and the temperature was increased. And stirred at 120° C. for 8 hours.
The obtained crude product was transferred to a separatory funnel and diluted with 100 ml of ethyl acetate, and 100 ml of ion-exchanged water was added for washing. Next, the same operation was performed twice using a saturated saline solution for washing. Then, it dehydrated using magnesium sulfate and the solvent was removed under reduced pressure. Finally, the product was purified by column chromatography on silica gel (solvent; hexane:toluene=1:1) to obtain N-(2-ethylhexyl)benzenamine with a yield of 66%.

(Ii) Synthesis of SQ-EP 3.36 g (15.5 mmol) of 1-bromo-3,5-dimethoxybenzene and 1.59 g (7.73 mmol) of N-(2-ethyl-1-hexyl)aniline were mixed with 80 ml of xylene. in a solution dissolved in tris (dibenzylideneacetone) dipalladium _{(0) (Pd 2 (dba} ) 3) 91mg (0.1mmol), potassium -t- butoxide 3.7 mg (33 mmol), tributyl phosphine 82 mg ( 0.4 mmol) was added and the mixture was heated under reflux for 25 hours to give N-(2-ethylhexyl)-3,5-dimethoxy-N-phenylbenzenamine.
A solution of 4.0 g (16 mmol) of boron tribromide dissolved in 16 ml of methylene chloride was added thereto, and the mixture was stirred at room temperature for 21 hours to give 5-(N-(2-ethylhexyl)-N-phenylamino). ) Benzene-1,3-diol was obtained.
A solution of 167 mg (1.47 mmol) of squaric acid dissolved in 45 ml of toluene and 15 ml of butanol was added thereto, and the mixture was heated under reflux for 24 hours to obtain SQ-EP with a yield of 83%.

The production of SQ-EP was confirmed by ¹ H-NMR, MS and elemental analysis.
The results are shown below.
¹ H NMR (400 MHz, CDCl ₃ ): δ 10.94 (s, 4H), 7.45 (t, 4H, J=7.2 Hz), 7.89 (t, 2H, J=7.2 Hz), 7.18(d, 4H J= 7.2 Hz), 5.74 (s, 4H), 3.66 (d, 4H, J=7.2 Hz), 1.73-1.67 (m, 2H), 1.43-1.16 (m, 16H), 0.87-0.80 (m, 12H) ppm
MS: m/z 706 [M] ⁺
Anal. Calcd for C ₄₄ H ₅₂ N ₂ O ₆ :C, 74.97; H, 7.44; N, 3.97%.Found: C, 75.04; H, 7.35; N, 3.92%.

（ii）ＳＱ−ＥＮの合成
１−ブロモ−３，５−ジメトキシベンゼン２．５４ｇ（１１．７ｍｍｏｌ）及びＮ−（２−エチルヘキシル）ナフタレン−２−アミン２．０１ｇ（７．８６ｍｍｏｌ）をキシレン５０ｍｌに溶解させた溶液中に、トリス（ジベンジリデンアセトン）ジパラジウム（０）（Ｐｄ₂（ｄｂａ）₃）９１ｍｇ（０．１ｍｍｏｌ）、カリウム−ｔ−ブトキシド８９７ｍｇ（８ｍｍｏｌ）、トリブチルホスフィン８２ｍｇ（０．４ｍｍｏｌ）を添加して、２５時間加熱還流することにより、Ｎ−（２−エチルヘキシル）−Ｎ−（３，５−ジメトキシフェニル）ナフタレン−２−アミンを得た。
ここに、三臭化ホウ素３．７５ｇ（１５ｍｍｏｌ）を塩化メチレン１５ｍｌに溶解させた溶液を添加し、室温で２０時間攪拌することにより、５−（Ｎ−（２−エチルヘキシル）−Ｎ−（ナフタレニル）アミノ）ベンゼン−１，３−ジオールを得た。
ここに、スクアリン酸２４４ｍｇ（２．１５ｍｍｏｌ）をトルエン４５ｍｌ及びブタノール１５ｍｌに溶解させた溶液を添加し、２２時間加熱還流することにより、収率８５％でＳＱ−ＥＮを得た。

¹Ｈ−ＮＭＲ、ＭＳ及び元素分析により、ＳＱ−ＥＮの生成を確認した。
結果を以下に示す。
¹H NMR(400 MHz, CDCl₃): δ 10.96 (s, 4H), 7.92 (d, 2H, J=8.0 Hz), 7.89-7.87 (m, 2H),7.83-7.8 (m, 2H), 7.66 (d, 2H, J=1.2 Hz), 7.56-7.52 (m, 4H), 7.28 (d,2H, J=8.6 Hz), 5.79 (s, 4H), 3.78 (d, 4H, J=7.2 Hz), 1.78-1.70 (m,2H), 1.50-1.18 (m, 16H), 0.85-0.81 (m, 12H) ppm
MS: m/z 806 [M]⁺
Anal. Calcd for C₅₂H₅₆N₂O₆:C, 77.58; H, 7.01; N, 3.48%. Found: C, 77.48; H, 6.85; N, 3.46%. [Example 3] Synthesis of SQ-EN (i) Synthesis of N-(2-ethylhexyl)naphthalene-2-amine 2.33 g (18 mmol) of 2-ethylhexylamine and 2.48 g (12 mol) of 2-bromonaphthalene were added to dimethyl. To a solution prepared by dissolving 6 ml of sulfoxide (DMSO), 228 mg (1.8 mmol) of copper(I) iodide, 2.21 g (24 mmol) of potassium carbonate and 230 mg (3 mmol) of L-proline were added at 90°C. The mixture was stirred for 11 hours, further heated and stirred at 120° C. for 23 hours.
The obtained crude product was transferred to a separatory funnel and diluted with 100 ml of ethyl acetate, and 100 ml of ion-exchanged water was added for washing. Next, the same operation was performed twice using a saturated saline solution for washing. Then, it dehydrated using magnesium sulfate and the solvent was removed under reduced pressure. Finally, the product was purified by column chromatography on silica gel (solvent; hexane:toluene=2:1) to obtain N-(2-ethylhexyl)naphthalen-2-amine with a yield of 68%.

(Ii) Synthesis of SQ-EN 2.54 g (11.7 mmol) of 1-bromo-3,5-dimethoxybenzene and 2.01 g (7.86 mmol) of N-(2-ethylhexyl)naphthalene-2-amine were added to 50 ml of xylene. in a solution dissolved in tris (dibenzylideneacetone) dipalladium _{(0) (Pd 2 (dba} ) 3) 91mg (0.1mmol), potassium -t- butoxide 897 mg (8 mmol), tributylphosphine 82 mg (0. 4 mmol) was added and the mixture was heated under reflux for 25 hours to obtain N-(2-ethylhexyl)-N-(3,5-dimethoxyphenyl)naphthalen-2-amine.
A solution prepared by dissolving 3.75 g (15 mmol) of boron tribromide in 15 ml of methylene chloride was added thereto, and the mixture was stirred at room temperature for 20 hours to give 5-(N-(2-ethylhexyl)-N-(naphthalenyl). ) Amino)benzene-1,3-diol was obtained.
A solution of 244 mg (2.15 mmol) of squaric acid dissolved in 45 ml of toluene and 15 ml of butanol was added thereto, and the mixture was heated under reflux for 22 hours to obtain SQ-EN with a yield of 85%.

The production of SQ-EN was confirmed by ¹ H-NMR, MS and elemental analysis.
The results are shown below.
¹ H NMR (400 MHz, CDCl ₃ ): δ 10.96 (s, 4H), 7.92 (d, 2H, J=8.0 Hz), 7.89-7.87 (m, 2H), 7.83-7.8 (m, 2H), 7.66 (d, 2H, J=1.2 Hz), 7.56-7.52 (m, 4H), 7.28 (d,2H, J=8.6 Hz), 5.79 (s, 4H), 3.78 (d, 4H, J=7.2 Hz) , 1.78-1.70 (m, 2H), 1.50-1.18 (m, 16H), 0.85-0.81 (m, 12H) ppm
MS: m/z 806 [M] ⁺
Anal. Calcd for C ₅₂ H ₅₆ N ₂ O ₆ :C, 77.58; H, 7.01; N, 3.48%.Found: C, 77.48; H, 6.85; N, 3.46%.

（ii）ＳＱ−ＥＢの合成
１−ブロモ−３，５−ジメトキシベンゼン１．０１ｇ（４．６３ｍｍｏｌ）及び４−（Ｎ−（２−エチルヘキシル）アミノ）ビフェニル８６８ｍｇ（３．０８ｍｍｏｌ）をキシレン３０ｍｌに溶解させた溶液中に、トリス（ジベンジリデンアセトン）ジパラジウム（０）（Ｐｄ₂（ｄｂａ）₃）２７ｍｇ（０．０３ｍｍｏｌ）、カリウム−ｔ−ブトキシド３４８ｍｇ（３．１ｍｍｏｌ）、トリブチルホスフィン３３ｍｇ（０．１７ｍｏｌ）を添加して、２０時間加熱還流することにより、Ｎ−（２−エチルヘキシル）−Ｎ−（３，５−ジメトキシフェニル）−４−ビフェニルアミンを得た。
ここに、三臭化ホウ素１．５ｇ（６ｍｍｏｌ）を塩化メチレン６ｍｌに溶解させた溶液を添加し、室温で１６時間攪拌することにより、５−（Ｎ−（２−エチルヘキシル）−Ｎ−（４−ビフェニルアミノ）ベンゼン−１，３−ジオールを得た。
ここに、スクアリン酸１０８ｍｇ（０．９５ｍｍｏｌ）をトルエン４５ｍｌ及びブタノール１５ｍｌに溶解させた溶液を添加し、２５時間加熱還流することにより、収率７７％でＳＱ−ＥＢを得た。

¹Ｈ−ＮＭＲ、ＭＳ及び元素分析により、ＳＱ−ＥＴＰＡ及びＳＱ−ＥＦの生成を確認した。
結果を以下に示す。
¹H NMR(400 MHz, CDCl₃): δ 10.97 (s, 4H), 7.64 (d, 4H, J=8.8Hz), 7.61 (d, 4H, J=7.6 Hz), 7.47 (t, 4H, J=7.8 Hz), 7.38 (t, 2H,J=7.4 Hz), 7.25 (d, 4H, J=6.8 Hz), 5.81 (s, 4H), 3.70 (d, 4H, J=7.2Hz), 1.7-1.72 (m, 2H), 1.48-1.22 (m, 16H), 0.87-0.83 (m, 12H) ppm
MS: m/z 856 [M]⁺
Anal. Calcd for C₅₆H₆₀N₂O₆:C, 78.48; H, 7.06; N, 3.27%. Found: C, 78.60; H, 7.20; N, 3.22%.
［実施例５、６］
下記構造式で表されるＳＱ−ＥＴＰＡ（実施例５）及びＳＱ−ＥＦ（実施例６）を、実施例１〜４と同様の手順で合成した。

合成スキームは以下のとおりである。

¹Ｈ−ＮＭＲ、ＭＳ及び元素分析により、ＳＱ−ＥＴＰＡ及びＳＱ−ＥＦの生成を確認した。
結果を以下に示す。
（１）ＳＱ−ＥＴＰＡ
¹H NMR(400 MHz, CDCl₃): δ 10.98 (s, 4H), 7.30 (t, 8H, J=8.0 Hz), 7.14 (d, 8H, J=8.8Hz), 7.08 (t, 8H, J=6.6 Hz), 6.99 (d, 4H, J=6.4 Hz), 5.80 (s, 4H), 3.63 (d, 4H,J=7.6 Hz), 1.77-1.73 (m, 2H), 1.46-1.21 (m, 16H), 0.89-0.82 (m, 12H) ppm
MS: m/z n.d. [M]⁺
Anal. Calcd for C₆₈H₇₀N₄O₆:C, 78.58; H, 6.79; N, 5.31%. Found: C, 78.50; H, 6.89; N, 5.31%.
（２）ＳＱ−ＥＦ
¹H NMR(400 MHz, CDCl₃): δ 10.95 (s, 4H), 7.76 (d, 2H, J=8.0 Hz), 7.73 (d, 2H, J=6.0 Hz), 7.45(d, 2H, J=6.0 Hz), 7.39-7.33 (m, 4H), 7.24 (d, 2H, J=2.0 Hz),7.14 (d, 2H, J=8.4 Hz), 5.82 (s, 4H), 3.70 (d, 4H, J=7.6 Hz), 1.75-1.68 (m,2H), 1.49 (s, 12H), 1.45-1.15 (m, 16H), 0.85-0.80 (m, 12H) ppm
MS: m/z 937 [M]⁺
Anal. Calcd for C₆₂H₆₈N₂O₆:C, 79.46; H, 7.31; N, 2.99%. Found: C, 79.39; H, 7.35; N, 2.97%.
［実施例６］
下記構造式で表されるＳＱ−ＥＳを以下の合成スキームに従って合成した。

¹Ｈ−ＮＭＲ、ＭＳ及び元素分析により、ＳＱ−ＥＳの生成を確認した。
結果を以下に示す。
¹H NMR(400 MHz, CDCl₃): δ 10.84 (s, 4H), 7.88-7.81 (m, 8H), 7.40-7.34 (m, 6H), 7.18-7.10 (m,8H), 7.75 (t, 6H, J=7.6 Hz), 7.53 (s, 2H), 5.66 (s, 4H), 3.45 (d, 4H, J=7.2 Hz),1.49-1.40 (m, 2H), 1.17-0.98 (m, 16H), 0.76 (t, 6H, J=6.8 Hz), 0.61 (t, 6H,J=6.8 Hz) ppm
MS: m/z n.d. [M]⁺
Anal. Calcd for C₈₂H₇₂N₂O₆:C, 83.36; H, 6.14; N, 2.37%. Found: C, 83.33; H, 6.36; N, 2.36%. Example 4 Synthesis of SQ-EB (i) Synthesis of N-(2-ethylhexyl)-4-biphenylamine 1.55 g (12 mmol) of 2-ethylhexylamine and 1.86 g (8 mmol) of 4-bromobiphenyl were added to dimethyl. 228 mg of copper(I) iodide, 2.21 g of potassium carbonate and 230 mg of L-proline were added to a solution dissolved in 8 ml of sulfoxide (DMSO), and the mixture was stirred at 90° C. for 18 hours.
The obtained crude product was transferred to a separatory funnel and diluted with 100 ml of ethyl acetate, and 100 ml of ion-exchanged water was added for washing. Next, the same operation was performed twice using saturated saline and washing was performed. Then, it dehydrated using magnesium sulfate and the solvent was removed under reduced pressure. Finally, purification by column chromatography on silica gel (solvent; hexane:toluene=2:1) gave N-(2-ethylhexyl)-4-biphenylamine in a yield of 39%.

(Ii) Synthesis of SQ-EB 1.01 g (4.63 mmol) of 1-bromo-3,5-dimethoxybenzene and 868 mg (3.08 mmol) of 4-(N-(2-ethylhexyl)amino)biphenyl in 30 ml of xylene. during dissolved solution, tris (dibenzylideneacetone) dipalladium _{(0) (Pd 2 (dba} ) 3) 27mg (0.03mmol), potassium -t- butoxide 348 mg (3.1 mmol), tributylphosphine 33 mg (0 .17 mol) was added and the mixture was heated under reflux for 20 hours to obtain N-(2-ethylhexyl)-N-(3,5-dimethoxyphenyl)-4-biphenylamine.
A solution of 1.5 g (6 mmol) of boron tribromide dissolved in 6 ml of methylene chloride was added thereto, and the mixture was stirred at room temperature for 16 hours to give 5-(N-(2-ethylhexyl)-N-(4 -Biphenylamino)benzene-1,3-diol was obtained.
A solution of 108 mg (0.95 mmol) of squaric acid dissolved in 45 ml of toluene and 15 ml of butanol was added thereto, and the mixture was heated under reflux for 25 hours to obtain SQ-EB with a yield of 77%.

The production of SQ-ETPA and SQ-EF was confirmed by ¹ H-NMR, MS and elemental analysis.
The results are shown below.
¹ H NMR (400 MHz, CDCl ₃ ): δ 10.97 (s, 4H), 7.64 (d, 4H, J=8.8Hz), 7.61 (d, 4H, J=7.6 Hz), 7.47 (t, 4H, J =7.8 Hz), 7.38 (t, 2H,J=7.4 Hz), 7.25 (d, 4H, J=6.8 Hz), 5.81 (s, 4H), 3.70 (d, 4H, J=7.2Hz), 1.7- 1.72 (m, 2H), 1.48-1.22 (m, 16H), 0.87-0.83 (m, 12H) ppm
MS: m/z 856 [M] ⁺
Anal. Calcd for C ₅₆ H ₆₀ N ₂ O ₆ :C, 78.48; H, 7.06; N, 3.27%.Found: C, 78.60; H, 7.20; N, 3.22%.
[Examples 5 and 6]
SQ-ETPA (Example 5) and SQ-EF (Example 6) represented by the following structural formulas were synthesized by the same procedure as in Examples 1 to 4.

The synthetic scheme is as follows.

The production of SQ-ETPA and SQ-EF was confirmed by ¹ H-NMR, MS and elemental analysis.
The results are shown below.
(1) SQ-ETPA
¹ H NMR (400 MHz, CDCl ₃ ): δ 10.98 (s, 4H), 7.30 (t, 8H, J=8.0 Hz), 7.14 (d, 8H, J=8.8Hz), 7.08 (t, 8H, J =6.6 Hz), 6.99 (d, 4H, J=6.4 Hz), 5.80 (s, 4H), 3.63 (d, 4H, J=7.6 Hz), 1.77-1.73 (m, 2H), 1.46-1.21 (m , 16H), 0.89-0.82 (m, 12H) ppm
MS: m/z nd [M] ⁺
Anal. Calcd for C ₆₈ H ₇₀ N ₄ O ₆ :C, 78.58; H, 6.79; N, 5.31%.Found: C, 78.50; H, 6.89; N, 5.31%.
(2) SQ-EF
¹ H NMR (400 MHz, CDCl ₃ ): δ 10.95 (s, 4H), 7.76 (d, 2H, J=8.0 Hz), 7.73 (d, 2H, J=6.0 Hz), 7.45(d, 2H, J =6.0 Hz), 7.39-7.33 (m, 4H), 7.24 (d, 2H, J=2.0 Hz), 7.14 (d, 2H, J=8.4 Hz), 5.82 (s, 4H), 3.70 (d, 4H , J=7.6 Hz), 1.75-1.68 (m, 2H), 1.49 (s, 12H), 1.45-1.15 (m, 16H), 0.85-0.80 (m, 12H) ppm
MS: m/z 937 [M] ⁺
Anal. Calcd for C ₆₂ H ₆₈ N ₂ O ₆ :C, 79.46; H, 7.31; N, 2.99%.Found: C, 79.39; H, 7.35; N, 2.97%.
[Example 6]
SQ-ES represented by the following structural formula was synthesized according to the following synthetic scheme.

The production of SQ-ES was confirmed by ¹ H-NMR, MS and elemental analysis.
The results are shown below.
¹ H NMR (400 MHz, CDCl ₃ ): δ 10.84 (s, 4H), 7.88-7.81 (m, 8H), 7.40-7.34 (m, 6H), 7.18-7.10 (m, 8H), 7.75 (t, 6H, J=7.6 Hz), 7.53 (s, 2H), 5.66 (s, 4H), 3.45 (d, 4H, J=7.2 Hz), 1.49-1.40 (m, 2H), 1.17-0.98 (m, 16H ), 0.76 (t, 6H, J=6.8 Hz), 0.61 (t, 6H, J=6.8 Hz) ppm
MS: m/z nd [M] ⁺
Anal. Calcd for C ₈₂ H ₇₂ N ₂ O ₆ :C, 83.36; H, 6.14; N, 2.37%.Found: C, 83.33; H, 6.36; N, 2.36%.

[Test Example 1] UV-visible spectroscopic analysis (UV-vis)
2 mg each of SQ-ET, SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF, and SQ-ES obtained in Examples 1 to 7 were weighed and dissolved in 1 ml of chloroform, A 2 mg/ml solution was prepared.
For each of SQ-ET, SQ-EP, SQ-EN, and SQ-EB, when chloroform solution was put into quartz glass for measurement (---), when cast film was used for measurement (-■-), cast When measured after thermal annealing treatment (70°C, 10 minutes) on the film (-◆-), when measured after thermal annealing treatment (120°C, 10 minutes) on the cast film (-▲-) UV-Vis absorption spectrum was measured. Regarding SQ-ETPA, SQ-EF, and SQ-ES, when measured as a cast film (-●-), when measured after subjecting the cast film to thermal annealing treatment (70°C, 10 minutes) (-■ -), the UV-Vis absorption spectrum was measured when the cast film was subjected to thermal annealing treatment (120°C, 10 minutes) and then measured (-◆-).
In the UV-Vis absorption spectrum, the wavelengths became longer in the order of SQ-EP<SQ-EB<SQ-EN<SQ-ET, but it was found that the energy difference was only about 0.03 eV.
The results are shown in Table 1 and FIG.

[Test Example 2] Differential scanning calorimetry (DSC) and differential thermal analysis (TGA)
5 mg each of SQ-ET, SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF, and SQ-ES obtained in Examples 1 to 7 were placed in an aluminum pan, and DSC and TGA were measured. did.
The results are shown in Table 1. The glass transition temperature (Tg) of SQ-ET, SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF, and SQ-ES was not observed, and the melting point (Tm) was 164 to 285°C. The 5% weight loss temperature (Td) was 305 to 343°C. Since all of SQ-ET, SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF, and SQ-ES have an aromatic hydrocarbon group, they have a rigid structure and high thermal stability. Found to have.

[Test Example 3] Cyclic voltammetry (CV)
2.11 mg of SQ-EP obtained in Examples 1 to 4, 2.41 mg of SQ-EN and 2.57 mg of SQ-EB were weighed and dissolved in 6 ml of methylene chloride to prepare 0.5 mM solutions. , CV measurement was performed. Although 1 mg of SQ-ET was weighed and not completely dissolved in 6 ml of methylene chloride, CV measurement was performed using it (solution of 0.17 mM or less).
The CV measurement was similarly performed on the SQ-ETPA, SQ-EF, and SQ-ES obtained in Examples 5 to 7.
The results are shown in Table 1. Regarding SQ-ET, SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF, and SQ-ES, almost no difference in energy level due to the difference in aromatic hydrocarbon groups was observed.

[Test Example 4] Solubility test SQ-ET, SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF, and SQ-ES obtained in Examples 1 to 7 were dissolved in chloroform, toluene, and Solubility was evaluated by dissolving in tetrahydrofuran (THF), 1,4-dioxane, chlorobenzene (CB; 120° C.) and o-dichlorobenzene (ODCB).
It was found that SQ-EN and SQ-ET in which a 2-naphthyl group and a 2-triphenylenyl group were introduced into an aromatic hydrocarbon group had low solubility.
The results are shown in Table 2.

ＳＱ−ＥＰ、ＳＱ−ＥＮ、ＳＱ−ＥＢ、ＳＱ−ＥＴＰＡ、ＳＱ−ＥＦ、及びＳＱ−ＥＳのそれぞれの素子特性結果を表３及び図３〜５に示す。 [Test Example 5] Solar cell characteristic evaluation An ITO substrate having an indium tin oxide (ITO) film coated on the entire surface of a glass substrate was prepared as an anode, and a 6 nm-thick oxide film was formed on the ITO electrode as a hole transport layer. A molybdenum (VI) (MoO ₃ ) layer was laminated, and the SQ-ET, SQ-EP, SQ-EN, SQ-EB, and SQ obtained in Examples 1 to 7 were used as the active layer on the layer. -ETPA, SQ-EF, SQ-ES and a mixture of phenyl C71 methyl butyrate (PC ₇₀ BM) as an acceptor material in a predetermined mass ratio are applied to a thickness of 70 to 100 nm, and then electron is applied thereon. As a transport layer, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) having a thickness of 10 nm was laminated, and an aluminum plate having a thickness of 100 nm was laminated as a cathode to form an element of a BHJ solar cell. It was produced and the characteristics were evaluated.

The device characteristic results of SQ-EP, SQ-EN, SQ-EB, SQ-ETPA, SQ-EF, and SQ-ES are shown in Table 3 and FIGS.

ＳＱ−ＥＰ及びＳＱ−ＥＢを用いた太陽電池素子において、熱アニールすることで、Ｖ_OC（開放電圧）、Ｊ_SC（短絡電流密度）及びＦＦ（曲線因子）のすべての値が低下し、ＰＣＥが低下する傾向が確認できた。一方、ＳＱ−ＥＮを用いた太陽電池素子では、熱アニールによる変化がみられなかった。
ＳＱ−ＥＰ：ＰＣ₇₀ＢＭ＝１：１．７（ＳＱ ４６．２％）の質量比で太陽電池素子を作製した結果、Ｖ_OC＝１．００Ｖ、Ｊ_SC＝１１．６８ｍＡ／ｃｍ^-2、ＦＦ＝０．４８であり、ＰＣＥが５．５３％と比較的高い効率を示した。そこで、ＳＱ−ＥＰの割合を多くした素子を作成し、素子の最適化をすれば、より高い効率を得られることが期待できる。しかしながら、ＳＱ−ＥＢについては、分子の平面性の観点から、効率の向上が期待できると考えられたが、ＳＱの割合を多くするほどＪ_SCの低下がみられ、ＳＱ−ＥＰと比べて効率が劣っていた。

In the solar cell element using SQ-EP and SQ-EB, all values of V _OC (open circuit voltage), J _SC (short circuit current density) and FF (fill factor) are decreased by thermal annealing, and PCE It was confirmed that the value decreased. On the other hand, in the solar cell element using SQ-EN, no change due to thermal annealing was observed.
As a result of producing a solar cell element with a mass ratio of SQ-EP:PC ₇₀ BM=1:1.7 (SQ 46.2%), V _OC =1.00 V, J _SC =1.68 mA/cm ⁻² , FF=0.48, and PCE showed a relatively high efficiency of 5.53%. Therefore, if an element with a high SQ-EP ratio is created and the element is optimized, higher efficiency can be expected to be obtained. However, regarding SQ-EB, it was considered that the efficiency could be expected to be improved from the viewpoint of the planarity of the molecule, but as the proportion of SQ increased, the J _SC decreased, and the efficiency was higher than that of SQ-EP. Was inferior.

1 Substrate 2 Cathode 3 Hole Transport Layer 4 Active Layer 5 Electron Transport Layer 6 Cathode

Claims (3)

A squarylium derivative which is a compound represented by the following general formula (1);

(In the general formula (1), R ₁ is independently an aromatic group, and R ₂ is independently a branched aliphatic hydrocarbon group having 4 or more carbon atoms.). The squarylium derivative according to claim 1, wherein in the general formula (1), R ₁ is an aromatic group having 6 to 50 carbon atoms, and R ₂ is an aliphatic hydrocarbon group having 4 to 20 carbon atoms. An organic thin-film solar cell using the squarylium derivative according to claim 1.

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