JP2007231040A - Phthalocyanine derivative and method for producing the same - Google Patents

Abstract

（式（１）中、Ｘ^1〜3はｔ−ブチル基、Ｘ⁴は−ＣＨ（ＣＨ₂ＣＯＯＨ）ＣＯＯＨである。ＭはＺｎである。）つまり、(a)フタロシアニン骨格におけるベンゼン環に対し、電子供与基と電子吸引基とを非対称に導入することで電子の流れを形成すること、(b)カルボキシ基を採用することで、色素増感型太陽電池に汎用される酸化チタンに対し強固に結合できることが組み合わされて高い電池性能を発揮できる。
【選択図】なしProvided is a phthalocyanine derivative having high efficiency when applied to a dye-sensitized solar cell.
A phthalocyanine derivative having an asymmetric structure represented by general formula (1).

(In the formula (1), X ^{1 to 3} is t- butyl, X ⁴ is .M is -CH (CH ₂ COOH) COOH is Zn.) That is, with respect to the benzene ring of (a) a phthalocyanine skeleton , Forming a flow of electrons by introducing an electron donating group and an electron withdrawing group asymmetrically; and (b) adopting a carboxy group makes it strong against titanium oxide commonly used in dye-sensitized solar cells. Combined with being able to be coupled to each other, high battery performance can be exhibited.
[Selection figure] None

Description

  The present invention relates to a phthalocyanine derivative suitable for a dye-sensitized solar cell and a method for producing the phthalocyanine derivative.

  Phthalocyanines have high thermal stability and chemical stability and have a very wide range of applications. As one of these application ranges, application to a dye-sensitized solar cell has been studied. When applied to a dye-sensitized solar cell, it is required to improve the energy conversion efficiency with respect to light.

Conventionally studied phthalocyanine derivatives include bis (3,4-dicarboxylpyridine) (1,4,8,11,15,18,22,25-octamethylphthalocyanine) ruthenium (II) (non- Patent Document 1, Patent Document 1), a compound in which carboxycatechol is coordinated with titanium (IV) tetra (t-butyl) phthalocyanine (Non-Patent Document 2), and a substituent in the peripheral part (benzene ring) of phthalocyanine Introduced compounds (compounds in which carboxy groups are introduced into all four benzene rings, etc .: Non-patent document 3, compounds in which glycine or tyrosine is introduced into all four benzene rings: non-patent document 4), and the like.
US Pat. No. 5,556,849 Nazeeruddin MK, Humphyry-Baker R, Gratzel M, Murrer BA, Chem. Commun., 1998, 719. Palomare E, Martines-Diaz MVM, Haque SA, Torres T, Durrant JR, Chem. Commun., 2004, 2112. Nazeeruddin MK, Humphyry-Baker R, Gratzel M, Wohrle D, Schnurpfeil G, Schneider G, Hirth A, Trombach N, J. Porphyrins and Phthalocyanines, 1999, 3, 230. He J, Benko G, Korodi F, Polyvka T, Lomoth R, Akermar B, Sun L, Hagfeldt A, Sundstrom V, J. Am. Chem. Soc., 2002, 124, 4922.

  However, conventional phthalocyanine derivatives cannot achieve sufficient performance as a dye-sensitized solar cell because the conversion efficiency η cannot be sufficient or the structure changes.

  The present invention has been made in view of the above circumstances, and an object to be solved is to provide a phthalocyanine derivative having high conversion efficiency when applied to a dye-sensitized solar cell.

Means and effects for solving the problems

  (1) The phthalocyanine derivative of the present invention that solves the above problems has an asymmetric structure represented by the following general formula (1).

(In the formula (1), X ¹ is an electron donating group consisting of R, OR and NRR ′ and a substituent selected from the first substituent group which is hydrogen; X ⁴ is from Y and —A—Y _m. Wherein Y is a substituent selected from the group of electron withdrawing groups consisting of COOH, COOR, SO ₃ H and PO ₃ H; A is a hydrocarbon group; m Is an integer of 1 or more; when m is 2 or more, each Y is bonded to a different carbon atom in A); X ² and X ³ are the first substituent group and the second substituent group R and R ′ are a linear or branched alkyl group, a phenyl group or a phenyl group in which one or more hydrogens are substituted with an alkyl group; n is X ^1-4 Each is an integer of 1 or more that can be independently selected; M is Cu, Zn, Ni, Co, Ru Al, Rh, Os, Pb, is selected from the group of elements consisting of Sn and P; pyridine or pyridine derivatives by the valence of M is coordinated to M)

In particular, in the general formula (1), the first substituent group is hydrogen, t-butyl group, OCH ₃ , OC ₂ H ₅ , OC ₃ H ₇ , OC ₅ H ₁₁ , OC ₆ H ₁₃ , OC ₇ H. ₁₅ , OC ₈ H ₁₇ , OC ₉ H ₁₉ , OC ₁₀ H ₂₁ , N (CH ₃ ) ₂ , N (C ₆ H ₅ ) ₂ and t-C ₄ H ₉ -ph-O- (ph is phenylene) Preferably, the second substituent group is —CH ₂ Y, —CH (CH ₂ Y) Y and —CH (CH ₂ Y) ₂ .

Further, it is desirable that X ² and X ³ are substituents selected from the electron donating group, and that an electron donating group is introduced into three benzene rings among the four benzene rings of the phthalocyanine derivative. .

  That is, (a) an electron donating group and an electron withdrawing group are introduced asymmetrically into the four benzene rings in the phthalocyanine skeleton to form an electron flow from the electron donating group to the electron withdrawing group (push- (Pull mechanism), (b) By combining the above-mentioned substituents as electron withdrawing groups, it is combined with strong bonding to semiconductors such as titanium oxide that are widely used in dye-sensitized solar cells.

  Therefore, (a) the flow of electrons from the electron donating group to the electron withdrawing group is formed, and (b) the energy generated by the light absorbed by the phthalocyanine derivative is obtained by bonding to titanium oxide etc. by the electron withdrawing group. When applied to a dye-sensitized solar cell, high battery performance can be exhibited.

Here, as a reference for determining whether or not the above-described “asymmetric structure” is used, the determination is based on whether or not the object is point-symmetric with respect to M located at the center. More specifically, “when all the substituents in the benzene ring at point symmetry with respect to M located in the center are the same type (electron donating group or electron withdrawing group) (that is, X ¹ and X ⁴ And X ² and X ³ are both the same type of substituent and number) ”is a“ symmetric structure ”, and the others are“ asymmetric structures ”. It does not mean that “one of the corresponding constituent elements is different with respect to M located in the center as an asymmetric structure”.

  (2) The method for producing a phthalocyanine derivative of the present invention that solves the above problems is a method for producing the phthalocyanine derivative described in (1) above.

And it has the process of making the phthalonitrile derivative as described in following General formula (2) and (3) react. Both reactions can be effectively advanced by a general operation such as heating. Wherein the substituents X ⁵ in the general formula (2) is a substituent corresponding to the first substituent group in the substituent X ^{1 to 3} having the phthalocyanine derivative. The substituents X ⁶ in the general formula (3) is a substituent corresponding to the second substituent group in the substituent X ^{2 to 4} having the phthalocyanine derivative.

(In the formulas (2) and (3), X ⁵ is an electron donating group consisting of R, OR and NRR ′ and a substituent selected from the first substituent group which is hydrogen; X ⁶ is Y and —A A substituent selected from a second substituent group consisting of —Y _m (Y is a substituent selected from the group of electron withdrawing groups consisting of COOH, COOR, SO ₃ H and PO ₃ H; Hydrogen group; m is an integer of 1 or more; and when m is 2 or more, each Y is bonded to a different carbon atom in A); R and R ′ are linear or branched alkyl groups; A phenyl group or a phenyl group in which one or more hydrogens are substituted with an alkyl group; n is an integer of 1 or more that can be independently selected for each of X ⁵ and ^V 6)

  Hereinafter, the phthalocyanine derivative of the present invention and the production method thereof will be described based on embodiments. The phthalocyanine derivative of the present invention can realize a dye-sensitized solar cell having high performance. Although it does not specifically limit as a dye-sensitized solar cell, The thing which has the electrode which consists of semiconductor fine particles, the pigment | dye carry | supported on the electrode, electrolyte, and a counter electrode is illustrated. The phthalocyanine derivative of the present invention is applied as a dye in a dye-sensitized solar cell.

(Phthalocyanine derivatives)
The phthalocyanine derivative of the present embodiment is a compound having a structure represented by the above general formula (1). A preferable structure for the general formula (1) will be described below.

X ¹ is an electron donating group consisting of R, OR and NRR ′ and a substituent selected from the first substituent group which is hydrogen. The first substituent group is particularly preferably an electron donating group. By using an electron donating group, the effect of pushing electrons toward the semiconductor electrode when applied to a dye-sensitized solar cell is enhanced. One or more X ¹ can be bonded to one benzene ring in the phthalocyanine skeleton. The first substituent group is preferably an alkyl group (R) and an alkoxy group (OR). As the alkyl group, a bulky substituent (for example, a t-butyl group) is desirable.

X ⁴ is a substituent selected from the second substituent group consisting of Y and —A—Y _m . Y is a substituent selected from the group of electron withdrawing groups consisting of COOH, COOR, SO ₃ H and PO ₃ H, and is preferably COOH. One or more X ⁴ can be bonded to one benzene ring in the phthalocyanine skeleton. A is a hydrocarbon group.

  Here, the electron withdrawing group represented by Y is preferably bonded via A rather than directly bonded to the benzene ring of the phthalocyanine skeleton. Examples of the hydrocarbon group represented by A include a saturated hydrocarbon group (alkylene group). In order to improve the electron withdrawing action and the bonding force to the semiconductor fine particles, it is desirable to bond Y to 2 or more (that is, m to 2 or more). In that case, each Y is bonded to a different carbon atom in the hydrocarbon group of A. This is because when bonded to the same carbon atom, the stability of the bonded substituent Y decreases.

X ² and X ³ are substituents selected from a first substituent group similar to X ¹ and a second substituent group similar to X ⁴ . In any case, it is desirable to select from the first substituent group. In particular, it is desirable that both are selected from the first substituent group (and also the electron donating group). By increasing the number of electron donating groups, the action of pushing out electrons toward the electrode made of semiconductor fine particles is enhanced.

The phthalocyanine derivative of this embodiment which is a phthalocyanine derivative having an asymmetric structure has been described above, but X ¹ and X ⁴ are selected from the first substituent group (or the second substituent group), and X ² and X 4 ^{Even if 3} is a compound that is formally outside the scope of the present invention selected from the second substituent group (or first substituent group), it will donate electrons of the electron donating group (or electron withdrawing group) By selecting substituents that have different (sucking) forces, if the electron flow becomes an asymmetric structure, there is a possibility that high performance will be exhibited.

  M is selected from the group of elements consisting of Cu, Zn, Ni, Co, Ru, Al, Rh, Os, Pb, Sn and P. As the oxidation number when these elements are introduced as M, Cu (II), Zn (II), Ni (II), Co (II), Ru (II), Al (III), Rh (III) , Os (II), Pb (IV), Sn (IV) and P (V). Of these elements, Zn is desirable as M. When the valence of M exceeds 4, a structure in which pyridine or a derivative thereof is coordinated can be employed.

(Method for producing phthalocyanine derivative)
The manufacturing method of the phthalocyanine derivative of this embodiment is a method of manufacturing the phthalocyanine derivative of this embodiment. And it is the method of making the phthalonitrile derivative as described in the said General formula (2) and (3) react. X ⁵ and X ⁶ in the general formulas (2) and (3) correspond to X ¹ to ⁴ of the phthalocyanine derivative to be produced. That is, the substituents X ⁵ and X ⁶ possessed by the phthalonitrile derivative are introduced as they are into the substituents X ¹ to X ⁴ of the phthalocyanine derivative. In principle, the place where the substituents X ⁵ and X ⁶ are introduced as X ^{1 to 4} of the phthalocyanine derivative cannot be controlled and is often determined by the probability.

  The phthalocyanine derivative of the present invention will be described below based on examples.

(Synthesis)
A phthalocyanine derivative (PCH001) described in the general formula (1) in which X ¹ to ³ is a t-butyl group and X ⁴ is CH (COOH) CH ₂ COOH was synthesized. The synthesis was performed according to the following reaction formula 1.

Synthesis of Compound 1 (Scheme 2): Nitrophthalonitrile (500 mg, 2.89 mmol), diethyl malonate (462 mg, 2.89 mmol), and K ₂ CO ₃ (1.18 g, 8.67 mmol) in 15 mL DMSO Dissolved in. The solution was under a nitrogen atmosphere. Heated at 80 ° C. for 4 hours. Thereafter, DMSO as a solvent was removed under reduced pressure.

  The target compound a was separated from the obtained solid using a silica gel column using a mixed solvent of ethyl acetate / hexane (10/90). Then, after making it react with KOH at room temperature for 3 hours in ethanol, ethanol was distilled off and the compound b was obtained. Compound b (800 mg, 2.48 mmol) and ethyl bromoacetate (480 mg, 2.88 mol) were dissolved in acetone / acetonitrile (2/1). Thereafter, the reaction was carried out by heating under reflux in a nitrogen atmosphere for 20 hours. The solvent was distilled off to obtain an oily reaction product. This reaction product was recrystallized using a chloroform / methanol solvent to obtain Compound 1.

  Synthesis of Compound 3: Compound 1 (1.000 g, 2.69 mmol), Compound 2 (commercial product, 1.484 g, 8.07 mmol) and diazabicycloundecene (DBU) (100 mg) were dissolved in pentanol. It was. Then, after heating and refluxing for 20 hours to carry out the reaction, the solvent was distilled off. By mixing Compound 1 and Compound 2 at a molar ratio of 1: 3, it was possible to mainly obtain Compound 3 containing 1: 3 substituents. The obtained mixture was separated on a silica gel column to obtain compound 3 (separation solvent was chloroform).

  Furthermore, recrystallization was repeated twice using chloroform / hexane for purification. The yield was 10%.

Synthesis of Compound 4: Compound 3 (100 mg, 0.1 mmol) and Zn (OAc) ₂ .2H ₂ O (110 mg, 0.5 mmol) were dissolved in 20 mL of DMF. The solution was refluxed until the Q band of phthalocyanine changed, and then the solvent was distilled off under reduced pressure. The obtained solid was separated and purified on a silica gel column (solvent: chloroform). ¹ H-NMR spectrum is shown in the lower column of FIG.

  Synthesis of target compound (PCH001): Compound 4 was hydrolyzed with Na / ethanol to obtain PCH001. Specifically, 1 g of sodium was dissolved after compound 4 (100 mg) was dissolved in 25 mL of ethanol. This reaction was carried out at room temperature with stirring for 7 days. Thereafter, the solvent was distilled off under reduced pressure, and the resulting solid was dissolved in ethanol, adjusted to pH 3 with concentrated hydrochloric acid, and precipitated again. The resulting precipitate was filtered off and dried under reduced pressure.

The obtained target compound (PCH001) was analyzed. The results are shown in FIG. In FIG. 1, a) shows the MALDI-TOF MS spectrum, b) shows the ¹ H-NMR spectrum in the upper column, and c) shows the results of elemental analysis.
IR (KBr): ν = 3423, 2957, 2923, 2857, 1713, 1612, 1396, 920, 525 cm ⁻¹ . _{MALDI-TOF: (C 48 H} 46 N 8 O 4 Zn) + = 863 (5%), 689 (30%).

(Synthesis)
A phthalocyanine derivative (PCH002: compound described in Non-Patent Document 3) in which X ¹ to ⁴ are all —COOH was synthesized in the same manner as PCH001 described above. The above-described method is the same method except that phthalonitrile carboxylic acid ethyl ester is used in place of compound 1 and compound 2 and reaction ii) is not performed.

(Evaluation: Production of photoelectrode)
A titanium oxide electrode (about 0.5 cm × 0.9 cm) was produced by screen printing. Specifically, a method of pasting titanium oxide nanoparticles with an organic substance and screen printing was performed in accordance with the method of “Gratzel” et al. A glass substrate on which a titanium oxide paste was printed was coated with a transparent oxide film (tin oxide doped with fluorine).

  After printing the titanium oxide paste, a titanium oxide electrode was obtained by sintering in air at 450 ° C. for 1 hour. The thickness of the formed titanium oxide film was about 6 μm. After dissolving each test dye in ethanol at a concentration of 0.01 mM, a titanium oxide electrode was immersed in the solution, and the test dye was adsorbed on the titanium oxide to form a photosensitized electrode. Immersion was performed at 25 ° C. for 13 hours.

A photocell was formed using the obtained photosensitized electrode and counter electrode. A two-electrode type photocell was adopted. Specifically, a cell is formed by combining a polyethylene separator having a thickness of 100 μm, an organic electrolyte (AH1, AH2, or AH3), and a counter electrode formed by sputtering Pt on glass coated with a transparent oxide film. Formed. An organic electrolyte was introduced into the formed gap. Where AH1 is 0.1 M I ₂ , 0.6 M 1,2-dimethyl-3-propylimidazolium iodide (DMPImI), and 0.5 M N -methoxybenzimidazole (NMBI), γ- It is an electrolyte dissolved in butyrolactone. AH2 is prepared by dissolving 0.1 M I ₂ , 0.9 M DMPImI, 0.5 M NMBI, and 0.1 M lithium saccharate (SacLi) in methoxypropionitrile. AH3 is N- methyl -N- butyl 0.6M - imidazolium iodide, I ₂ of 0.05M, Li of 0.05M and the 0.5M t-butylpyridine valeronitrile / acetonitrile, (50/50 , V / v).

First, evaluation about PCH001 was performed. The UV-VIS absorption spectrum of the 0.01 mmol ethanol solution is shown in FIG. 2 (a), and the absorption spectrum in a state adsorbed on the titanium oxide surface is shown in FIG. 2 (b). As is clear from FIG. 2A, an absorption maximum (ε = 191000 dm ³ mol ⁻¹ cm ⁻¹ ) was shown at 680 nm. Further, as apparent from FIG. 2B, the absorption maximum was shifted 11 nm toward the long wavelength side when adsorbed on the titanium oxide surface.

  Subsequently, the photoelectric conversion efficiency (IPCE) of the photoelectric cell measured using AH1-3 electrolyte is shown in FIG. FIG. 3A shows the IPCE at AH1 (...) And AH2 (−), and FIG. 3B shows the IPCE at AH3. The maximum IPCE values for AH1-3 were 22%, 23% and 75%, respectively.

Photocurrent-voltage characteristics were evaluated for cells using PCH001 and PCH002 as the dye. Evaluation was performed by irradiating simulated sunlight (AM1.5: 100 mW / cm ² ). The results are shown in Table 1. Here, J _SC is a short circuit current, Voc is an open circuit voltage, FF is a fill factor, and I ₀ is a photon amount. Efficiency and η were determined by {J _SC (mAcm ⁻² ) × Voc (V) × FF} ÷ I ₀ (Wm ⁻² ) × 100 (%). Here, AH4 employed as an electrolyte in PCH002 is obtained by dissolving 0.5 M LiI and 0.05 M LiI ₃ in propylene carbonate. The maximum value of IPCE in PCH002 was 43%.

  As is clear from Table 1, PCH002 having a control structure could not obtain sufficient efficiency as compared with PCH001 having an asymmetric structure. This is presumably because the cell employing PCH001 exerted the effect of promoting electron transfer by arranging the electron-withdrawing group and the electron-donating group asymmetrically in the phthalocyanine skeleton. PCH001 showed high thermal stability even in an atmosphere of 150 ° C. or higher.

(Reference: Synthesis method)
A phthalocyanine derivative (compound 9) in which X ¹ to ³ is a t-butyl group, X ⁴ is a carboxy group and n in X ⁴ is 2 was synthesized according to the following reaction formula 2. Compound 6 (t-butylisoindoline: 603 mg, 3 mmol) and compound 7 (dicyanoisoindoline: 195 mg, 1 mmol) were dissolved in 20 mL of dimethylaminoethanol, and then refluxed for 4 hours. The solvent was distilled off under reduced pressure, and the obtained solid was purified with a silica gel column using chloroform / methanol (90/10) as a solvent.

The obtained compound 8 was dissolved in DMF together with Zn (OAc) ₂ and refluxed for 2 hours. Then, the solvent was distilled off under reduced pressure, and recrystallization was performed using a methanol / hexane mixed solvent to obtain a compound 9.

It is an analytical data of the phthalocyanine derivative of a present Example. It is a spectrum which shows the light absorbency of the phthalocyanine derivative of a present Example. It is a graph which shows IPCE using the various electrolyte in the phthalocyanine derivative of a present Example.

Claims (4)

A phthalocyanine derivative having an asymmetric structure represented by the following general formula (1).

(In the formula (1), X ¹ is an electron donating group consisting of R, OR and NRR ′ and a substituent selected from the first substituent group which is hydrogen; X ⁴ is from Y and —A—Y _m. Wherein Y is a substituent selected from the group of electron withdrawing groups consisting of COOH, COOR, SO ₃ H and PO ₃ H; A is a hydrocarbon group; m Is an integer of 1 or more; when m is 2 or more, each Y is bonded to a different carbon atom in A); X ² and X ³ are the first substituent group and the second substituent group R and R ′ are a linear or branched alkyl group, a phenyl group or a phenyl group in which one or more hydrogens are substituted with an alkyl group; n is X ^1-4 Each is an integer of 1 or more that can be independently selected; M is Cu, Zn, Ni, Co, Ru Al, Rh, Os, Pb, is selected from the group of elements consisting of Sn and P; pyridine or pyridine derivatives by the valence of M is coordinated to M) In the general formula (1), the first substituent group is hydrogen, t-butyl group, OCH ₃ , OC ₂ H ₅ , OC ₃ H ₇ , OC ₅ H ₁₁ , OC ₆ H ₁₃ , OC ₇ H ₁₅ , OC ₈ H ₁₇ , OC ₉ H ₁₉ , OC ₁₀ H ₂₁ , N (CH ₃ ) ₂ , N (C ₆ H ₅ ) ₂ and t-C ₄ H ₉ -ph-O- (ph is phenylene);
2. The phthalocyanine derivative according to claim 1, wherein the second substituent group is —CH ₂ Y, —CH (CH ₂ Y) Y, and —CH (CH ₂ Y) ₂ . The phthalocyanine derivative according to claim 1 or 2, wherein X ² and X ³ are substituents selected from the electron donating group. A method for producing the phthalocyanine derivative according to any one of claims 1 to 3,
The manufacturing method of the phthalocyanine derivative characterized by having the process of making the phthalonitrile derivative as described in following General formula (2) and (3) react.

(In the formulas (2) and (3), X ⁵ is an electron donating group consisting of R, OR and NRR ′ and a substituent selected from the first substituent group which is hydrogen; X ⁶ is Y and —A A substituent selected from a second substituent group consisting of —Y _m (Y is a substituent selected from the group of electron withdrawing groups consisting of COOH, COOR, SO ₃ H and PO ₃ H; Hydrogen group; m is an integer of 1 or more; and when m is 2 or more, each Y is bonded to a different carbon atom in A); R and R ′ are linear or branched alkyl groups; A phenyl group or a phenyl group in which one or more hydrogens are substituted with an alkyl group; n is an integer of 1 or more that can be independently selected for each of X ^{5 and 6} )

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