JP5761768B2 - 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. As a method for converting solar energy into electricity, silicon-based semiconductor solar cells have been developed. 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. The increase in the number of colors of cells enables absorption of a wider range of wavelengths and the expectation of efficient energy conversion, as well as providing an attractive product in appearance.

  Conventionally, most of the dyes that have been used in dye-sensitized solar cells are polypyridine Ru-based dyes that exhibit red color (Patent Documents 1 to 4).

  In recent years, dyes having a skeleton other than polypyridine have been developed, and for example, use of porphyrin dyes (Patent Documents 5 and 6) and phthalocyanine dyes has been attempted (Patent Documents 7 and 8).

JP 2003-272721 A Japanese Patent Laid-Open No. 2003-212851 JP 2005-47857 A JP 2005-120042 A Japanese Patent Application No. 2012-027274 Japanese Patent Application No. 2012-027276 Japanese Patent No. 4953658 JP 2011-60669 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 is a green solar cell photosensitizing dye having a good photoelectric conversion efficiency. We found out that there was a present invention.

(In the formula (1), A is unsubstituted or substituted alkene, alkyne, aryl or heteroaryl, n is 0 or an integer of 1 to 3, and R ¹ and R ² are each independently methyl. A lower alkyl group selected from the group consisting of a group, an ethyl group, and an n-butyl group, and M is an n-valent metal ion or silicon.)

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

It is the structure of the solar cell using the photosensitizing dye of this invention. It is the absorption spectrum of the photosensitizing dye A of this invention, and the comparative examples 1 and 2. FIG. It is an absorption spectrum of photosensitizing dyes A to E of the present invention and Comparative Examples 3 and 4. It is the spectral sensitivity of the solar cell using the photosensitizing dye A of this invention, and the comparative example and 2. FIG. It is the spectral sensitivity of a solar cell using the photosensitizing dyes A to E of the present invention and Comparative Examples 3 and 4. It is the external appearance of the solar cell produced using the photosensitizing dye A of this invention, and the comparative examples 1 and 2. FIG.

  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 is a phthalocyanine complex having a structure represented by the following formula (1) or a salt thereof.

(In the formula (1), A is unsubstituted or substituted alkene, alkyne, aryl or heteroaryl, n is 0 or an integer of 1 to 3, and R ¹ and R ² are each independently methyl. A lower alkyl group selected from the group consisting of a group, an ethyl group, and an n-butyl group, and M is an n-valent metal ion or silicon.)
The photosensitizing dye of the present invention has a phthalocyanine skeleton coordinated with an n-valent central element M.

  In the formula (1), A is unsubstituted or substituted alkene, alkyne, aryl or heteroaryl, and n is 0 or an integer of 1 to 3. Examples of the alkene of A include, but are not limited to, ethylene, butene, hexene, octene, decene, and dodecene. Examples of the alkyne of A include, but are not limited to, ethyne, butyne, and hexyne. 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.

  The aryl or heteroaryl of A may have, as a substituent, C1-20 alkyl, C1-20 alkoxy, hydroxy, or halogen which may contain a branch. The substituent is preferably electron donating. Preferably, said A is substituted with one substituent.

In the formula (1), R ¹ and R ² are each independently a lower alkyl group selected from the group consisting of a methyl group, an ethyl group, and an n-butyl group. Preferably, R ¹ and R ² are both methyl groups. When R1 and R2 are selected from a lower alkyl group, the photosensitizing dye of the present invention is easily dissolved in an organic solvent and easy to handle. Also, in the case of synthesizing the photosensitizing dye, the yield is expected to be improved as compared with the case where R1 and R2 have bulky substituents due to the improvement in solubility and handleability.

  The central element M is selected from the group of metal elements consisting of zinc, aluminum, magnesium, copper, nickel, cobalt, ruthenium, rhodium, osmium, lead, and tin, or silicon. Zinc is preferable.

  The photosensitizing dye of the present invention which is a phthalocyanine complex represented by the formula (1) or a salt thereof includes, for example, the following compounds AG or salts thereof. 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 9).

  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 Compound A (M = Zn))
Synthesis of compound 1

  Under a nitrogen atmosphere, 4,5-dichlorophthalonitrile (19.0 g, 96.4 mmol), 2,6-dimethylphenol (35.3 g, 289 mmol), potassium carbonate (46.6 g, 337 mmol) in DMF (190 mL). In addition, the mixture was stirred at 100 ° C. for 16 hours. After cooling, it was dispersed in water, and the precipitated solid was collected by filtration and dried under reduced pressure to obtain a crude product. This was purified by silica gel column chromatography. Subsequently, recrystallization was performed using ethyl acetate to obtain Compound 1 (20.6 g, 55.4 mmol, yield 58%, white solid).

Synthesis of compound 2

  Under a nitrogen atmosphere, 4-iodophthalonitrile (11.1 g, 43.7 mmol), 4- (methoxycarbonyl) phenylboronic acid (15.7 g, 87.2 mmol), sodium carbonate (18.5 g, 175 mmol), tetrakis ( Triphenylphosphine) palladium (4.96 g, 4.3 mmol) was added to a mixed solution of DMF (480 mL) and water (155 mL), and the mixture was stirred at 90 ° C. for 2 hours. After cooling, ethyl acetate and water were added, and the organic layer was extracted. The extracted organic layer was dried over sodium sulfate and concentrated under reduced pressure to obtain a crude product. This was purified by silica gel column chromatography to obtain compound 2 (7.58 g, 28.9 mmol, 66% yield, white solid).

Synthesis of Compound A (M = Zn)

  Under a nitrogen atmosphere, Compound 1 (34.15 g, 92.7 mmol), Compound 2 (8.11 g, 30.9 mol), and zinc chloride (8.42 g, 61.8 mmol) were added to 1 L of 2-dimethylaminoethanol. Stir at 4 ° C. for 4 hours. After cooling, the mixture was concentrated under reduced pressure, and methanol was added to the residue. The precipitated solid was collected by filtration and dried under reduced pressure to obtain a crude product. The obtained crude product was purified by silica gel column chromatography to obtain a methyl ester intermediate.

The intermediate was dissolved in a mixed solution of 600 mL of THF, 100 mL of ethanol and 100 mL of 1M aqueous sodium hydroxide solution, and heated to reflux for 1 hour. After cooling, the mixture was neutralized with hydrochloric acid, the organic solvent was distilled off under reduced pressure, and the residue was extracted with chloroform. The extracted organic layer was washed with water, dried over sodium sulfate, and concentrated under reduced pressure to obtain a crude product. This was purified by silica gel column chromatography. Subsequently, recrystallization was performed using ethyl acetate to obtain Compound A (M = Zn) (4.66 g, 3.28 mmol, yield 11%, green solid, TOF-MS m / z 1417 [M + H] ⁺ ).

(Synthesis of Compound B (M = Zn))
Synthesis of methyl 4-bromo-2-fluorobenzoate

  4-Bromo-2-fluorobenzoic acid (5.00 g, 22.8 mmol) was dissolved in 50 mL of dehydrated methanol under a nitrogen atmosphere. Concentrated sulfuric acid 2mL was added to this, and it heated and refluxed for 4 hours. After cooling, the reaction solution was diluted with ethyl acetate and cold water and then separated. The organic layer was washed with water and concentrated under reduced pressure to obtain methyl 4-bromo-2-fluorobenzoate (5.12 g, 22.0 mmol, yield 96%, white solid).

Synthesis of compound 3

  Under a nitrogen atmosphere, 4-bromophthalonitrile (30 g, 144.9 mmol), bis (pinacolato) diboron (40.5 g, 159.4 mmol), potassium acetate (42.7 g, 434.7 mmol), [1,1′- Bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (4.70 g, 5.76 mmol) was added to 300 mL of dehydrated DMF and stirred at 80 ° C. for 7 hours. After cooling, the reaction solution was diluted with ethyl acetate and cold water and then separated. The organic layer was washed with water and concentrated under reduced pressure to obtain a crude product. This was dissolved in ethyl acetate, hexane was added, and the precipitated insoluble matter was filtered off. The filtrate was distilled off under reduced pressure to obtain Compound 3 (19.5 g, 76.7 mmol, yield 53%, tan solid). Obtained.

Synthesis of compound 2b

  Under nitrogen atmosphere, methyl 4-bromo-2-fluorobenzoate (0.33 g, 1.29 mmol), compound 3 (0.30 g, 1.29 mmol), potassium acetate (0.38 g, 3.87 mmol), [1 , 1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (42 mg, 0.052 mmol) was added to 10 mL of dehydrated DMF and stirred at 80 ° C. for 3 hours. After cooling, it was dispersed in water, and the precipitated solid was collected by filtration and dried under reduced pressure to obtain a crude product. This was purified by silica gel column chromatography to obtain compound 2b (0.13 g, 0.46 mmol, yield 36%, white solid).

Synthesis of compound B (M = Zn)

  Under a nitrogen atmosphere, compound 2b (0.13 g, 0.46 mmol), compound 1 (0.51 g, 1.38 mmol), zinc chloride (0.13 g, 0.92 mmol) were added to 10 mL of 2-dimethylaminoethanol, and 140 Stir at 0 ° C. for 2 hours. After cooling, the mixture was concentrated under reduced pressure, and methanol was added to the residue. The precipitated solid was collected by filtration and dried under reduced pressure to obtain a crude product. The obtained crude product was purified by silica gel column chromatography to obtain a methyl ester intermediate.

The intermediate was dissolved in a mixed solution of 10 mL of THF, 2 mL of ethanol, and 0.5 mL of 1M aqueous sodium hydroxide solution and heated to reflux for 1 hour. After cooling, the mixture was neutralized with hydrochloric acid, the organic solvent was distilled off under reduced pressure, and the residue was extracted with chloroform. The extracted organic layer was washed with water, dried over sodium sulfate, and concentrated under reduced pressure to obtain a crude product. This was purified by silica gel column chromatography to obtain compound B (M = Zn) (70 mg, 0.048 mmol, yield 10%, green solid, TOF-MS m / z 1434 [M] ⁺ ).

(Synthesis of Compound C (M = Zn))
Synthesis of methyl 4-bromo-2-chlorobenzoate

  4-Bromo-2-chlorobenzoic acid (5.00 g, 21.2 mmol) was dissolved in 50 mL of dehydrated methanol under a nitrogen atmosphere. Concentrated sulfuric acid (2 mL) was added thereto, and a reaction similar to the synthesis of methyl 4-bromo-2-fluorobenzoate was carried out. Methyl 4-bromo-2-chlorobenzoate (4.84 g, 19.4 mmol, 92% yield) , A red-orange transparent oil).

  Synthesis of compound 2c

  Under nitrogen atmosphere, methyl 4-bromo-2-chlorobenzoate (1.00 g, 4.01 mmol), compound 3 (1.02 g, 4.01 mmol), potassium acetate (1.18 g, 12.0 mmol), [1 , 1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (0.13 g, 0.16 mmol) is added to 30 mL of dehydrated DMF, and a reaction similar to the synthesis of compound 2b is carried out. .77 g, 2.60 mmol, 65% yield, white solid).

Synthesis of compound C (M = Zn)

Under a nitrogen atmosphere, compound 2c (0.20 g, 0.674 mmol), compound 1 (0.75 g, 2.02 mmol), and zinc chloride (0.18 g, 1.35 mmol) were added to 10 mL of 2-methylaminoethanol, and compound was added. Reaction similar to the synthesis | combination of B was performed, and the compound C (84 mg, 0.058 mmol, yield 8.6%, green solid, TOF-MS m / z1452 [M] ^<+> ) was obtained.

(Synthesis of Compound D (M = Zn, R = H))
Synthesis of compound 2d

  Under nitrogen atmosphere, methyl 4-bromo-2-methoxybenzoate (1.00 g, 4.08 mmol), compound 3 (1.25 g, 4.90 mmol), potassium acetate (1.20 g, 12.2 mmol), [1 , 1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (0.13 g, 0.16 mmol) is added to 17 mL of dehydrated DMF, and a reaction similar to the synthesis of compound 2b is carried out. .43 g, 1.47 mmol, 36% yield, white solid).

Synthesis of compound D (M = Zn, R = H)

Under a nitrogen atmosphere, compound 2d (0.20 g, 0.684 mmol), compound 1 (0.76 g, 2.05 mmol), and zinc chloride (0.19 g, 1.36 mmol) were added to 10 mL of 2-dimethylaminoethanol, and compound was added. The same reaction as in the synthesis of B was performed, and methyl ether and methyl ester were cleaved at the same time to obtain o-hydroxyl compound D (M = Zn, R = H) (40 mg, 0.028 mmol, yield 4.0%, A green solid, TOF-MS m / z 1435 [M] ⁺ ) was obtained.

(Synthesis of Compound E (M = Zn))
Synthesis of methyl 4-bromo-3-fluorobenzoate

  4-Bromo-3-fluorobenzoic acid (5.00 g, 22.8 mmol) was dissolved in 50 mL of dehydrated methanol under a nitrogen atmosphere. To this was added 2 mL of concentrated sulfuric acid, and the same reaction as the synthesis of methyl 4-bromo-2-fluorobenzoate was carried out. 5.10 g of methyl 4-bromo-3-fluorobenzoate, 22.0 mmol, 96% yield, (White solid) was obtained.

Synthesis of compound 2e

  Under nitrogen atmosphere, methyl 4-bromo-3-fluorobenzoate 4.90 g, 21.0 mmol), compound 1 (5.34 g, 21.0 mmol), potassium acetate (6.20 g, 63.1 mmol), 1,1 '--Bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (700 mg, 0.857 mmol) is added to 200 mL of dehydrated DMF, and a reaction similar to the synthesis of compound 2b is performed to obtain a crude product of compound 2e. Obtained. This was purified by silica gel column chromatography to obtain compound 2e (1.35 g, 4.82 mmol, yield 33%, white solid).

Synthesis of Compound E (M = Zn)

Under a nitrogen atmosphere, compound 2e (0.20 g, 0.71 mmol), compound 1 (0.79 g, 2.14 mmol), and zinc chloride (0.19 g, 1.43 mmol) were added to 10 mL of 2-dimethylaminoethanol, and compound was added. Reaction similar to the synthesis | combination of B was performed, and the compound E (82 mg, 0.057 mmol, yield 8.0%, green solid, TOF-MS m / z1437 [M] ^<+> ) was obtained.

(Synthesis of Comparative Example)
As comparative examples, the following compounds were synthesized.

(Synthesis of Comparative Example 1)
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 2)
Synthesis of 2-formyl-5-hexylthiophene

  A reaction vessel containing 2-hexylthiophene (20.0 g) and dehydrated THF (100 ml) was cooled to −10 ° C., and n-butyllithium (90 ml) was added dropwise thereto. After 2 hours, DMF (18 ml) was slowly added dropwise. After stirring this solution at 10 ° C. for 1 hour, a saturated aqueous ammonium chloride solution was added dropwise, and the mixture was extracted with hexane. The organic layer was washed with a saturated aqueous sodium chloride solution and dried over anhydrous sodium sulfate. The oily substance obtained by distilling off the solvent was developed and separated by a silica gel column (chloroform / heptane = 1/1) to obtain the product (2-formyl-5-hexylthiophene, 22.8 g).

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-methoxycarbonylphenyl) porphyrin zinc (II) complex

  5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin (1.35 g) was dissolved in chloroform (160 ml). Thereto was added dropwise zinc acetate dihydrate (3.77 g) dissolved in methanol (38 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 (5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin zinc (II) complex, 1.53 g) was obtained.

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

5,10,15-tri (5-hexylthiophen-2-yl) -20- (4-methoxycarbonylphenyl) porphyrin zinc (II) complex (1.40 g) dissolved in THF (210 ml) and water (70 ml) I let you. Thereto was added 48% sodium hydroxide (7.0 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-tri (5-hexylthiophen-2-yl) -20- ( 4-carboxylphenyl) porphyrin zinc (II) complex, 1.27 g) was obtained.
¹ H-NMR (δ _H / ppm, CDCl ₃ , 400 MHz) 0.98 (t, 9H), 1.45 (m, 12H), 1.61 (quin, 6H), 1.96 (quin, 6H) , 3.14 (t, 6H), 7.17 (d, 3H), 7.71 (d, 3H), 8.35 (d, 2H), 8.53 (d, 2H), 8.89 ( d, 2H), 9.23 (d, 2H), 9.24 (s, 4H)

(Synthesis of Comparative Example 3)
Synthesis of compound 2s

  4-Bromophthalonitrile (0.28 g, 1.36 mmol), 2-nitro-4- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) benzoic acid under nitrogen atmosphere Acid methyl (0.50 g, 1.63 mmol), potassium acetate (0.40 g, 4.08 mmol), [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (41 mg, 0 .05 mmol) was added to 15 mL of dehydrated DMF, and a reaction similar to the synthesis of compound 2b was performed to obtain compound 2s (0.36 g, 1.17 mmol, yield 86%, white solid).

Synthesis of Comparative Example 3

Under a nitrogen atmosphere, compound 1 (0.54 g, 1.47 mmol), compound 2s (0.15 g, 0.49 mmol), and zinc chloride (0.13 g, 0.98 mmol) were added to 10 mL of 2-dimethylaminoethanol, and compound was added. Reaction similar to the synthesis | combination of B was performed, and the comparative example 3 (19 mg, 0.013 mol, yield 3%, green solid, TOF-MS m / Z1462 [M + H] ^< +>) was obtained.

(Synthesis of Comparative Example 4)
Synthesis of methyl 4-bromo-2,6-difluorobenzoate

  Under a nitrogen atmosphere, 4-bromo-2,6-difluorobenzoic acid (1.00 g, 4.22 mmol) was dissolved in 20 mL of dehydrated methanol. To this was added 0.5 mL of concentrated sulfuric acid, and a reaction similar to the synthesis of methyl 4-bromo-2-fluorobenzoate was performed, and methyl 4-bromo-2,6-difluorobenzoate (0.64 g, 2.55 mmol, Yield 60%, pale yellow solid).

Synthesis of compound 2t

  Under nitrogen atmosphere, methyl 4-bromo-2,6-difluorobenzoate (0.64 g, 2.55 mmol), compound 3 (0.78 g, 3.06 mmol), potassium acetate (0.75 g, 7.65 mmol), [1,1′-Bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (82 mg, 0.10 mmol) was added to 10 mL of dehydrated DMF, and a reaction similar to the synthesis of compound 2b was performed to obtain compound 2t (0 .42 g, 1.41 mmol, yield 55%, white solid).

Synthesis of Comparative Example 4

Under a nitrogen atmosphere, compound 1 (0.74 g, 2.01 mmol), compound 2t (0.20 g, 0.67 mmol), zinc chloride (0.18 g, 1.34 mmol) was added to 15 mL of 2-dimethylaminoethanol, and compound was added. Reaction similar to the synthesis | combination of B was performed, and the comparative example 4 (79 mg, 0.054 mmol, yield 8%, green solid, TOF-MS m / Z1455 [M] ^<+> ) was obtained.

(Measurement of ultraviolet absorption spectrum)
About the compound A prepared by the said synthesis example, the solution of 0.003 mM density | concentration was prepared using the DMF solvent, and the absorption spectrum was measured using the spectrophotometer (JASCO Corporation JASCO V-670). The results are shown in FIG.

  For Comparative Examples 1 and 2, 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.

  Similarly to Compound A above, for Compounds B to E and Comparative Examples 3 and 4, solutions having a concentration of 0.003 mM were prepared using a DMF solvent, and absorption spectra were measured. The results are shown in FIG.

(Preparation of dye-sensitized solar cell)
(1) Dye-sensitized solar cells using various compounds A to E and Comparative Examples 1 to 4 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 on which the power generation layer was formed in a dye solution [concentration: 0.1 mM, solvent: ethanol] overnight at room temperature, the 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 was iodine 0.1M, lithium iodide 0.1M, 1-propyl-3-methylimidazolium iodide 0.8M, N-methylbenzimidazole 0.5M, 3-methoxypropio. A solution using nitrile as a solvent was used.

  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 FIGS. Moreover, the external appearance of these photovoltaic cells is shown in FIG.

(performance test)
The performance of the dye-sensitized solar cell obtained as described above was evaluated.

Each of the prepared cells was measured for cell conversion efficiency under irradiation conditions of AM1.5 and 1SUN (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 bright green cell.

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

Claims (8)

A photosensitizing dye for solar cells, which is a phthalocyanine complex represented by the following formula (1) or a salt thereof.
(In the formula (1), A is unsubstituted or substituted alkene, alkyne, aryl or heteroaryl, and when A has a substituent, the A may be branched C1-20 alkyl. , C1-20 alkoxy, hydroxy, substituted with one substituent selected from the group consisting of halogen, n is an integer of 0 or 1-3, R ¹ and R ² are each independently a methyl group, A lower alkyl group selected from the group consisting of an ethyl group and an n-butyl group, and M is an n-valent metal ion or silicon)   2. The light according to claim 1, wherein M is selected from a group of metal elements consisting of zinc, aluminum, magnesium, copper, nickel, cobalt, ruthenium, rhodium, osmium, lead, and tin, or silicon. Sensitizing dye.   A represents unsubstituted or substituted ethylene, butene, hexene, octene, decene, dodecene, ethyne, butyne, hexyne, phenylene ring, naphthalene ring, thiophene ring, pyrrole ring, furan ring, imidazole ring, pyrazole ring, oxazole. The ring is selected from the group consisting of a ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, and a 1,2,3-triazine ring. 2. The photosensitizing dye according to 2. 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 The photosensitizing dye according to any one of claims 1 to 3 , 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 any one of claims 1 to 4 , wherein the photosensitizing dye is substituted. A photosensitizing dye for solar cells, which is a phthalocyanine complex represented by any one of the following structures A to G or a salt thereof.



An oxide semiconductor electrode, wherein the photosensitizing dye according to any one of claims 1 to 6 is adsorbed on an oxide semiconductor. A dye-sensitized solar cell comprising the oxide semiconductor electrode, transparent electrode, electrolyte and counter electrode of claim 7 .