JP6028296B2 - Photosensitizing dye, metal oxide semiconductor electrode containing the dye, and dye-sensitized solar cell - Google Patents

Description

  The present invention relates to a novel green photosensitizing dye, a metal oxide semiconductor electrode containing the dye, and a dye-sensitized solar cell containing the dye.

  With the depletion of fossil fuels and the global warming caused by their combustion, the development of new energy alternatives has become an urgent task. Solar energy is a clean and environmentally friendly energy source with sufficient potential to support the next generation of sustainable development. Silicon-based semiconductor solar cells have been developed as a method for converting solar energy into electricity. However, the silicon used here needs to have a very high purity, and a high production cost is required because of the enormous amount of energy and complicated processes that are consumed in the purification process.

  Since dye-sensitized solar cells have a relatively high conversion efficiency and are lower in cost than conventional solar cells, they are currently attracting widespread academic and commercial attention. In particular, this dye-sensitized solar cell reported by Gretzell et al. In 1991 has reached a photoelectric conversion efficiency of 10 to 11%. This makes it possible to absorb light in the visible light region by adsorbing the dye on the surface of the nanotitania particles, and the role of the dye is particularly important since it has a light collecting action. Such dyes include cis-bis (isothiocyanato) -bis (2,2′-bipyridine-4,4′-carboxylate) ruthenium (II) called N3, cis-bis (isothiocyanato) -bis called N719. (2,2′-Bipyridine-4,4′-carboxylate) ruthenium (II) bis (tetra n-butylammonium) and cis-bis (isothiocyanato)-(2,2′-bipyridine-4,4) called Z907 '-Carboxylate)-(2,2'-bipyridine-4,4'-dinonyl) ruthenium (II) is well known.

  In addition, unlike a silicon-based semiconductor solar cell, a dye-sensitized solar cell can be multicolored by using a plurality of dyes.

  However, the dyes conventionally used in dye-sensitized solar cells are mainly polypyridine Ru-based dyes, most of which show red (Patent Documents 1 to 4).

JP 2003-272721 A Japanese Patent Laid-Open No. 2003-212851 JP 2005-47857 A JP 2005-120042 A International Publication No. 2012/014414

 An object of the present invention is to provide a novel green light sensitizing dye that contributes to multicolorization of cells and has a good photoelectric conversion efficiency, a metal oxide semiconductor electrode in which this is adsorbed on an oxide semiconductor, and the oxidation It is an object to provide a dye-sensitized solar cell using a semiconductor electrode.

  As a result of intensive studies to achieve the above object, the present inventor has found that the compound having the structure of the following formula (1) is a green solar cell photosensitizing dye having good photoelectric conversion efficiency. The headline and the present invention were completed.

(In the formula (1), A is a conjugated system, B consists of structural formula b ₁ -b ₂ or b ₁ -b ₂ -b _3, wherein b _1, b _2, and b ₃ are each unsubstituted Or selected from substituted aryl or unsubstituted or substituted heteroaryl, wherein B comprises at least one aryl and at least one heteroaryl, wherein R is C1-20 alkyl or C1-C20 alkoxy is there.)

  The solar cell using the photosensitizing dye of the present invention can have a green cell and good photoelectric conversion efficiency.

It is the structure of the solar cell using the photosensitizing dye of this invention. It is an absorption spectrum of photosensitizing dye A and B of this invention, and Comparative Examples 1-3. It is the spectral sensitivity of photosensitizing dye A and B of this invention, and Comparative Examples 1-3. It is an external appearance of the solar cell produced using photosensitizing dye AC of this invention, and Comparative Examples 1-4.

  The present invention relates to a photosensitizing dye, and an oxide semiconductor electrode and a solar cell using the same. Hereinafter, preferred embodiments of the present invention will be described in detail. The following embodiment is merely an example of the present invention, and those skilled in the art can change the design as appropriate.

(Photosensitizing dye)
The photosensitizing dye of the present invention has a structure represented by the following formula (1).

(In the formula (1), A is a conjugated system, B consists of structural formula b ₁ -b ₂ or b ₁ -b ₂ -b _3, wherein b _1, b _2, and b ₃ are each unsubstituted Or selected from substituted aryl or unsubstituted or substituted heteroaryl, wherein B comprises at least one aryl and at least one heteroaryl, wherein R is C1-20 alkyl or C1-C20 alkoxy is there.)

The photosensitizing dye of the present invention has a porphyrin skeleton in which Zn ²⁺ ions are coordinated as a central metal.

  In the formula (1), A is a conjugated system. Although not limited thereto, A may be unsubstituted or substituted alkene, alkyne, aryl, and heteroaryl. Specific examples of the alkene of A include ethylene, butene, hexene, octene, decene, dodecene and the like. Specific examples of the alkyne of A include ethyne, butyne, hexyne and the like. The aryl of A includes, but is not limited to, a phenylene ring and a naphthalene ring, and the heteroaryl of A includes a thiophene ring, a pyrrole ring, a furan ring, an imidazole ring, a pyrazole ring, an oxazole ring, and an isoxazole ring. , 5-membered rings such as thiazole ring and isothiazole ring, and 6-membered rings such as pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring and 1,2,3-triazine ring. Preferably, it is monocyclic aryl or heteroaryl.

  Said A may have a C1-20 alkyl which may contain a branch, C1-20 alkoxy, and a halogen as a substituent.

In the formula (1), B comprises the structural formula b ₁ -b ₂ or b ₁ -b ₂ -b ₃ , and the b ₁ , b ₂ , and b ₃ are each an unsubstituted or substituted aryl or non-substituted Selected from substituted or substituted heteroaryl, said B comprises at least one said aryl and at least one said heteroaryl. Examples of the aryl of B include a phenylene ring and a naphthalene ring. Examples of the heteroaryl of B include a thiophene ring, a pyrrole ring, a furan ring, an imidazole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, and the like, a pyridine ring, and a pyrimidine ring. , Pyridazine ring, pyrazine ring, 6-membered ring such as 1,2,3-triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, phthalazine ring, pteridine ring, coumarin ring, chromone ring, 1,4-benzodiazepine ring, indole And a polycyclic hetero ring such as a ring, a benzimidazole ring, a benzofuran ring, a purine ring, an acridine ring, a phenoxazine ring and a phenothiazine ring.

  The aryl or heteroaryl of B may have a substituent, but is not limited thereto, and may be substituted with C1-20 alkyl, C1-20 alkoxy, and halogen which may include a branch.

  In the formula (1), R is a C1-20 alkyl or C1-C20 alkoxy which may contain a branch.

  The photosensitizing dye of the present invention having the formula (1) includes, for example, the following compounds A to C. In addition, regarding the manufacturing method of the photosensitizing dye of this invention, it explains in full detail in the Example shown below.

(Metal oxide semiconductor electrode)
The present invention further relates to a metal oxide semiconductor electrode using the photosensitizing dye. The metal oxide semiconductor electrode of the present invention is obtained by adsorbing the above-described photosensitizing dye of the present invention on the surface of a metal oxide semiconductor electrode. This metal oxide semiconductor electrode is preferably a porous electrode. Accordingly, the substantial surface area of the electrode can be increased, the amount of photosensitizing dye adsorbed on the electrode can be increased, and the photoelectric conversion efficiency of the solar cell including the metal oxide semiconductor electrode can be increased. Will be able to.

  The metal oxide semiconductor of the present invention includes titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxide, or strontium titanate, titanium. A compound having a perovskite structure such as calcium oxide, sodium titanate, barium titanate, or potassium niobate can be used.

  Any known method can be used as a method for adsorbing the photosensitizing dye on the metal oxide semiconductor thin film. For example, a method of immersing a metal oxide semiconductor thin film such as titanium dioxide in the photosensitizing dye solution of the present invention at a predetermined temperature (dip method, roller method, air knife method, etc.), or metal oxidation of the photosensitizing dye solution Examples thereof include a method of applying to a semiconductor layered surface (wire bar method, application method, spin method, spray method, offset printing method, screen printing method, etc.).

(Dye-sensitized solar cell)
The present invention further relates to a dye-sensitized solar cell including the transparent electrode 1, the metal oxide semiconductor electrode 2, the electrolyte 3, and the counter electrode 4 (see FIG. 1).

  The transparent electrode 1 is configured by forming a transparent conductive layer on a transparent substrate (not shown). As the transparent substrate, a general-purpose glass substrate, quartz substrate, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, and other transparent plastic substrates can be used. The transparent conductive layer is composed of tin oxide, fluorine-doped tin oxide, ITO, ATO, zinc oxide, aluminum-doped zinc oxide, or a light-transmissive transparent conductive layer in which a coating of tin oxide or fluorine-doped tin oxide is provided on the surface thereof. Can be configured.

As the electrolyte 3, a solid state or a liquid state can be used. Specifically, iodine-based electrolyte, bromine-based electrolyte, selenium-based electrolyte, sulfur-based electrolyte, quinone / hydroquinone-based electrolyte, and cobalt complex-based electrolyte can be used. But are not limited to, I _2, LiI, dimethylpropyl imidazolium iodide, t- butyl pyridine, 1,2-dimethyl-3-propyl imidazolium iodide, etc., acetonitrile, methoxy acetonitrile, propylene carbonate, ethylene carbonate, A solution or the like dissolved in an electrically inert organic solvent such as 3-methoxypropionyl or propylene carbonate is preferably used.

  Further, for the purpose of reducing volatilization of components in the electrolyte composition, a gelling agent or a polymer crosslinking monomer may be dissolved in the electrolyte composition described above and used as a gel electrolyte. Further, an all-solid-state dye-sensitized solar cell may be formed by dissolving in the polymer using the electrolyte and the plasticizer and volatilizing and removing the plasticizer.

  The counter electrode 4 is composed of, for example, a conductive layer such as platinum, carbon, nickel, chromium, stainless steel, fluorine-doped tin oxide, and ITO formed on a metal substrate such as titanium, Al, and SUS, a glass substrate, or a plastic substrate. Is done. The counter electrode 4 may include a catalyst layer (not shown) such as platinum or carbon, and the platinum may be treated with a sulfur material (see, for example, Patent Document 5).

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

(Synthesis of Dye A)
Synthesis of 4- (5-hexylthiophen-2-yl) benzaldehyde

  To the reaction vessel, 4-bromobenzaldehyde (9.17 g), 2- (5-hexylthiophen-2-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (14.00 g) , Tripotassium phosphate (11.00 g), toluene (150 ml) and dichloro [1,1-bis (diphenylphosphino) ferrocene] palladium (II) (0.20 g) were added and stirred and heated to 70 ° C. did. After completion of the reaction, the reaction solution was passed through celite, and the filtrate was concentrated. This was developed and separated on a silica gel column (chloroform) to obtain a product (4- (5-hexylthiophen-2-yl) benzaldehyde, 7.79 g).

Synthesis of 5- (4-methoxycarbonylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin

  In a reaction vessel, pyrrole (0.92 g), 4- (5-hexylthiophen-2-yl) benzaldehyde (2.79 g), methyl terephthalaldehyde (0.56 g), chloroform (130 ml) and ethanol (0.5 ml) ) And cooled to about 10 ° C. Thereto, boron trifluoride (0.47 g) was added dropwise and stirred as such for 2 hours. To this solution was added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (2.32 g), and the mixture was further stirred for 1 hour. The reaction solution was passed through celite and silica gel, and the filtrate was concentrated to obtain a crude product. This was developed and separated by a silica gel column (chloroform / hexane = 3/2), and the product (5- (4-methoxycarbonylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) was obtained. ) Phenyl] porphyrin, 0.34 g).

Synthesis of 5- (4-methoxycarbonylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin zinc (II) complex

  5- (4-Methoxycarbonylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin (0.33 g) was dissolved in chloroform (16.5 ml). Thereto was added dropwise zinc acetate dihydrate (0.62 g) dissolved in methanol (6 ml). After confirming the completion of the reaction by TLC, water was added to separate the layers. The organic layer was washed with water and dried over anhydrous sodium sulfate. The solvent was distilled off to obtain a crude product. This was developed and separated on a silica gel column (chloroform), and the purple product (5- (4-methoxycarbonylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin zinc) (II) complex, 0.33 g) was obtained.

Synthesis of 5- (4-carboxylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin zinc (II) complex

5- (4-Methoxycarbonylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin zinc (II) complex (0.31 g) in THF (30 ml) and water (7 ml). Thereto was added 48% sodium hydroxide (0.70 g), and the mixture was heated at about 68 ° C. until the raw material disappeared. After completion of the reaction, THF was distilled off. 3% aqueous formic acid was added to the residue to make it weakly acidic. The purple precipitate was collected and the purple product (5- (4-carboxylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin zinc (II) complex, 0.28 g) was obtained.
¹ H-NMR (δ _{H /} ppm, THF, 400 MHz) 0.96 (t, 9H), 1.50-1.40 (m, 18H), 1.81 (quin, 6H), 2.95 (t , 6H), 6.92 (d, 3H), 7.51 (d, 3H), 8.00 (d, 6H), 8.20 (d, 6H), 8.31 (d, 2H), 8 .43 (d, 2H), 8.84-8.96 (m, 8H)

(Synthesis of Dye B)
Synthesis of 2- (4-hexylphenyl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane

  To the reaction vessel, 1-bromo-4-hexylbenzene (10.00 g), bis (pinacolato) diborane (12.60 g), potassium acetate (12.13 g) and DMF (200 ml) were added and stirred. Bis (triphenylphosphine) palladium (II) dichloride (0.61 g) was added thereto and heated to 80 ° C. After heating and stirring overnight, chloroform and water were added to separate and wash. The organic layer was dried over anhydrous sodium sulfate and the solvent was distilled off. This was purified with a silica gel column (hexane → hexane / chloroform = 1/2) to give the product (2- (4-hexylphenyl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane. 9.30 g).

Synthesis of 5- (4-hexylphenyl) thiophene-2-carbaldehyde

  2- (4-Hexylphenyl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5.10 g), 5-bromothiophene-2-carbaldehyde (4.07 g) in a reaction vessel A 10% aqueous sodium carbonate solution (55 ml) and dioxane (60 ml) were added and stirred. Tetrakistriphenylphosphine palladium (598 mg) was added thereto and heated to 80 ° C. After heating and stirring overnight, chloroform and water were added to separate and wash. The organic layer was dried over anhydrous sodium sulfate and the solvent was distilled off. This was purified by a silica gel column (hexane / chloroform = 4/1 → chloroform) to obtain a product (5- (4-hexylphenyl) thiophene-2-carbaldehyde, 4.70 g).

Synthesis of 5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4-methoxycarbonylphenyl) porphyrin

  Pyrrole (1.58 g), 5- (4-hexylphenyl) thiophene-2-carbaldehyde (4.80 g), methyl terephthalaldehyde (0.97 g) were dissolved in chloroform (180 ml) and ethanol (3 ml), Cooled to about 10 ° C. Thereto was added boron trifluoride (0.83 g) dropwise, and the mixture was stirred as it was for 2 hours. To this solution was added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (4.10 g), and the mixture was further stirred for 1 hour. The reaction solution was passed through celite and silica gel, and the filtrate was concentrated to obtain a crude product. This was developed and separated by a silica gel column (chloroform), and the product (5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4-methoxycarbonylphenyl) porphyrin, 0 .50 g) was obtained.

Synthesis of 5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4-methoxycarbonylphenyl) porphyrin zinc (II) complex

  5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4-methoxycarbonylphenyl) porphyrin (0.50 g) was dissolved in chloroform (120 ml). Thereto was added dropwise zinc acetate dihydrate (0.70 g) dissolved in methanol (60 ml). After confirming the completion of the reaction by TLC, water was added to separate the layers. The organic layer was washed with water and dried over anhydrous sodium sulfate. The solvent was distilled off to obtain a crude product. This was developed and separated on a silica gel column (hexane / chloroform = 2/1), and the purple product (5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4- Methoxycarbonylphenyl) porphyrin zinc (II) complex, 0.40 g) was obtained.

Synthesis of 5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4-carboxylphenyl) porphyrin zinc (II) complex

5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4-methoxycarbonylphenyl) porphyrin zinc (II) complex (0.40 g) in THF (50 ml) and water (30 ml). 48% sodium hydroxide (3 ml) was added thereto, and the mixture was heated at about 68 ° C. After completion of the reaction, THF was distilled off. 3% aqueous formic acid was added to the residue to make it weakly acidic. Extraction was performed with chloroform, and the organic layer was washed with water. The organic layer was dried over anhydrous sodium sulfate and the solvent was distilled off. This was purified with a silica gel column (chloroform → chloroform / ethyl acetate = 4/1) to give a purple product (5,10,15-tri [5- (4-hexylphenyl) thiophen-2-yl] -20- (4-carboxylphenyl) porphyrin zinc (II) complex, 0.30 g) was obtained.
¹ H-NMR (δ _H / ppm, CDCl ₃ , 400 MHz) 0.92 (t, 9H), 1.30-1.42 (m, 18H), 1.69 (quin, 6H), 2.69 ( t, 6H), 7.31 (d, 6H), 7.67 (d, 3H), 7.79 (d, 6H), 7.87 (d, 3H), 8.36 (d, 2H), 8.52 (d, 2H), 8.91-9.34 (m, 8H)
(Synthesis of Comparative Example)
As comparative examples, the following compounds were synthesized.

(Synthesis of Comparative Example 1)
Synthesis of 5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin

  To a reaction vessel, pyrrole (2.73 g), 2-formyl-5-hexylthiophene (6.0 g), methyl terephthalaldehyde (1.67 g), chloroform (1500 ml) and ethanol (6 ml) were added, and the temperature was about 10 ° C. Cooled to. Thereto was added boron trifluoride (1.45 g) dropwise, and the mixture was stirred for 2 hours. To this solution was added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (6.94 g), and the mixture was further stirred for 1 hour. The reaction solution was passed through celite and silica gel, and the filtrate was concentrated to obtain a crude product. This was developed and separated by a silica gel column (chloroform / hexane = 3/1), and the product (5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin, 1.43 g) was obtained.

Synthesis of 5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-carboxylphenyl) porphyrin

5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin (0.15 g) was dissolved in THF (50 ml) and water (10 ml). Thereto was added 48% sodium hydroxide (1.50 g), and the mixture was heated at about 68 ° C. until the raw material disappeared. After completion of the reaction, THF was distilled off. 3% aqueous formic acid was added to the residue to make it weakly acidic. The precipitate was collected, developed and separated on a silica gel column (chloroform → chloroform / THF = 5/1), and the purple product (5,10,15-tri (5-hexylthiophen-2-yl) -20- ( 4-carboxylphenyl) porphyrin, 0.10 g).
¹ H-NMR (δ _H / ppm, CDCl ₃ , 400 MHz) 0.98 (t, 9H), 1.40-1.50 (m, 12H), 1.60 (quin, 6H), 1.96 ( quin, 6H), 3.14 (t, 6H), 7.17 (d, 3H), 7.71 (d, 3H), 8.35 (d, 2H), 8.54 (d, 2H), 8.78-9.14 (m, 8H)

(Synthesis of Comparative Example 2)
Synthesis of 5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin copper (II) complex

  5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin (0.53 g) was dissolved in chloroform (100 ml). Thereto was added dropwise copper acetate (0.50 g) dissolved in methanol (40 ml). After confirming the completion of the reaction by TLC, the solvent was distilled off to obtain a crude product. This was developed and separated on a silica gel column (chloroform / hexane = 1/1), and a purple product (5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin was obtained. Copper (II) complex, 0.42 g) was obtained.

Synthesis of 5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-carboxylphenyl) porphyrin copper (II) complex

  5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin copper (II) complex (0.42 g) dissolved in THF (100 ml) and water (10 ml) I let you. Thereto was added 48% sodium hydroxide (1.50 g), and the mixture was heated at about 68 ° C. until the raw material disappeared. After completion of the reaction, THF was distilled off. 3% aqueous formic acid was added to the residue to make it weakly acidic. The precipitate was collected, developed and separated on a silica gel column (chloroform → chloroform / THF = 5/1), and the purple product (5,10,15-tri (5-hexylthiophen-2-yl) -20- ( 4-carboxylphenyl) porphyrin copper (II) complex, 0.40 g) was obtained.

(Synthesis of Comparative Example 3)
Synthesis of 5,10,15-trimesityl-20- (4-methoxycarbonylphenyl) porphyrin

  To a reaction vessel, pyrrole (2.45 g), 2,4,6-trimethylbenzaldehyde (4.06 g), methyl terephthalaldehyde (1.50 g), chloroform (540 ml) and ethanol (7 ml) were added, and the temperature was about 10 ° C. Cooled to. Thereto was added boron trifluoride (1.43 g) dropwise, and the mixture was stirred as it was for 2 hours. To this solution was added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (6.22 g), and the mixture was further stirred for 1 hour. The reaction solution was passed through celite and silica gel, and the filtrate was concentrated to obtain a crude product. This was developed and separated by a silica gel column (chloroform / hexane = 3/2) to obtain a product (5,10,15-trimesityl-20- (4-methoxycarbonylphenyl) porphyrin, 1.13 g).

Synthesis of 5,10,15-trimesityl-20- (4-methoxycarbonylphenyl) porphyrin zinc (II) complex

  5,10,15-trimesityl-20- (4-methoxycarbonylphenyl) porphyrin (0.60 g) was dissolved in chloroform (70 ml). To this was added dropwise zinc acetate dihydrate (1.98 g) dissolved in methanol (20 ml). After confirming the completion of the reaction by TLC, water was added to separate the layers. The organic layer was washed with water and dried over anhydrous sodium sulfate. The solvent was distilled off to obtain a crude product. This was developed and separated on a silica gel column (chloroform) to obtain a purple product (5,10,15-trimesityl-20- (4-methoxycarbonylphenyl) porphyrin zinc (II) complex, 0.60 g).

Synthesis of 5,10,15-trimesityl-20- (4-carboxylphenyl) porphyrin zinc (II) complex

5,10,15-trimesityl-20- (4-methoxycarbonylphenyl) porphyrin zinc (II) complex (0.60 g) was dissolved in THF (60 ml) and water (20 ml). Thereto was added 48% sodium hydroxide (2.0 g), and the mixture was heated at about 68 ° C. until the raw material disappeared. After completion of the reaction, THF was distilled off. 3% aqueous formic acid was added to the residue to make it weakly acidic. The precipitate was collected, developed and separated on a silica gel column (chloroform → chloroform / THF = 5/1), and the purple product (5,10,15-trimesityl-20- (4-carboxylphenyl) porphyrin zinc (II) A complex, 0.45 g) was obtained.
¹ H-NMR (δ _H / ppm, CDCl ₃ , 400 MHz) 1.85 (s, 18H), 2.64 (s, 9H), 7.29 (s, 6H), 8.37 (s, 2H) 8.51 (s, 2H), 8.78-8.83 (m, 8H)

(Synthesis of Comparative Example 4)
Synthesis of 5- (4-carboxylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin

5- (4-Methoxycarbonylphenyl) -10,15,20-tri [4- (5-hexylthiophen-2-yl) phenyl] porphyrin (15 mg) was dissolved in THF (10 ml) and water (3 ml). . 48% sodium hydroxide (0.30 g) was added thereto, and the mixture was heated at about 68 ° C. After completion of the reaction, THF was distilled off. 3% aqueous formic acid was added to the residue to make it weakly acidic. The purple precipitate was recovered, developed and separated on a silica gel column (chloroform → chloroform / THF = 5/1), and the purple product (5- (4-carboxylphenyl) -10,15,20-tri [4- ( 5-hexylthiophen-2-yl) phenyl] porphyrin, 14 mg).
¹ H-NMR (δ _H / ppm, THF, 400 MHz) -2.65 (s, 2H), 0.95 (t, 9H), 1.40-1.50 (m, 18H), 1.81 ( quin, 6H), 2.94 (t, 6H), 6.92 (d, 3H), 7.51 (d, 3H), 8.02 (d, 6H), 8.21 (d, 6H), 8.32 (d, 2H), 8.46 (d, 2H), 8.83-8.94 (m, 8H)

(Measurement of ultraviolet absorption spectrum)
For various dyes A and B prepared in the above synthesis example and Comparative Examples 1 to 3, solutions having a concentration of 0.015 mM were prepared using a DMF solvent, and absorption spectra were measured using a spectrophotometer (SHIMADZU UVmini 1240). . The results are shown in FIG.
(Preparation of dye-sensitized solar cell)
(1) Dye-sensitized solar cells using various dyes A and B and Comparative Examples 1 to 3 prepared according to the above synthesis examples were prepared by the following procedure.

  i. Screen printing a titanium oxide paste [catalyst conversion PST-21NR] to a film thickness of 8 μm by screen printing on a 1 cm square area on a substrate (fluorine-doped tin oxide film-coated glass plate, 35 mm × 33 mm), After drying, a titanium oxide paste [PST-400C manufactured by Catalytic Chemicals] was further screen-printed thereon with a film thickness of 4 μm. This was fired at 500 ° C. to form a power generation layer.

  ii. By immersing the electrode forming the power generation layer in a dye solution [concentration: 0.3 mM, solvent: mixed solvent of acetonitrile / t-butanol 1/1 (v / v)] at 40 ° C. for 2 hours, A dye was supported on the titanium oxide of the power generation layer to obtain an anode electrode.

  iii. Adhesive is applied around the power generation layer of the anode electrode, and the anode electrode and a platinum-coated titanium plate (cathode electrode) treated with thioacetamide having a separately prepared electrolyte injection hole are bonded with the adhesive. The electrodes were bonded so that both electrodes were arranged in parallel at a constant interval of about 50 μm.

  iv. Next, an electrolytic solution was injected from the electrolytic solution inlet. Here, the electrolytic solution used is a solution using iodine 0.1M, 1-propyl-3-methylimidazolium iodide 0.8M, N-methylbenzimidazole 0.5M, 3-methoxypropionitrile as a solvent. Using.

  v. The electrolyte injection hole was sealed using an adhesive, and solder for terminal removal was applied onto the anode electrode to complete the experimental cell.

(Measurement of spectral sensitivity)
The spectral sensitivity of the produced solar battery cell was measured with a spectral sensitivity measuring device (CEP-2000 manufactured by Spectrometer Co., Ltd.). The results are shown in FIG. Moreover, the external appearance of these photovoltaic cells is shown in FIG.

(performance test)
The initial photoelectric conversion efficiency of the solar cell produced as described above was measured under irradiation conditions of AM1.5 and 1 SUN (100 mW / cm ² ). The results are shown in Table 1.

The photoelectric conversion efficiency was calculated by the following formula.
Photoelectric conversion efficiency (%) =
100 × [(Short-circuit current density × Open circuit voltage × Curve factor) / (Irradiated solar energy)]
As shown in Table 1 above, the dye-sensitized solar cell produced using the photosensitizing dye of the present invention showed high photoelectric conversion efficiency and was able to provide a green cell.

DESCRIPTION OF SYMBOLS 1 Transparent electrode 2 Metal oxide semiconductor electrode 3 Electrolyte 4 Counter electrode

Claims (7)

The photosensitizing dye for solar cells which has following formula (1).
(In the formula (1), A is a conjugated system, B consists of the structural formula b ₁ -b ₂ or b ₁ -b ₂ -b ₃ , and the B binds to the porphyrin skeleton through the b ₁ , B ₁ is unsubstituted or substituted aryl; b ₂ and b ₃ are each selected from unsubstituted or substituted aryl or unsubstituted or substituted heteroaryl; and B is at least one The aryl and at least one heteroaryl, wherein A is an unsubstituted or substituted ethylene, ethyne, phenylene ring, naphthalene ring, thiophene ring, pyrrole ring, furan ring, imidazole ring, pyrazole ring, oxazole ring, Isoxazole ring, thiazole ring, isothiazole ring, pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, and 1,2,3-tri Selected from the group consisting of azine rings, R is C1-20 alkyl or C1 C20 alkoxy)   2. The photosensitization according to claim 1, wherein A is substituted with a substituent selected from the group consisting of C1-20 alkyl, C1-20 alkoxy, and halogen, which may include a branch. Pigment.   The aryl is a phenylene ring or a naphthalene ring, and the heteroaryl is a thiophene ring, pyrrole ring, furan ring, imidazole ring, pyrazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, pyridine ring, pyrimidine. Ring, pyridazine ring, pyrazine ring, 1,2,3-triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, phthalazine ring, pteridine ring, coumarin ring, chromone ring, 1,4-benzodiazepine ring, indole ring, benzimidazole 3. The photosensitizing dye according to claim 1, wherein the photosensitizing dye is a heteroaryl selected from the group consisting of a ring, a benzofuran ring, a purine ring, an acridine ring, a phenoxazine ring, and a phenothiazine ring.   The substituted aryl or the substituted heteroaryl is optionally substituted by a substituent selected from the group consisting of C1-20 alkyl, C1-20 cycloalkyl, C1-20 alkoxy, and halogen, which may include a branch. The photosensitizing dye according to claim 1, wherein the photosensitizing dye is substituted. A photosensitizing dye for solar cells having the following structure A.
  An oxide semiconductor electrode, wherein the photosensitizing dye according to any one of claims 1 to 5 is adsorbed on an oxide semiconductor.   A dye-sensitized solar cell comprising the oxide semiconductor electrode, transparent electrode, electrolyte and counter electrode of claim 6.