KR20120126498A - Novel organic dyes and a dye-sensitized solar cell comprising the organic dyes - Google Patents

Abstract

PURPOSE: An organic dye is provided to improve flowability of an electron by accepting a functional group for preventing re-combination with other electrolyte in one electron donor and to maximize photoelectric conversion efficiency of high Jsc(short circuit photocurrent density). CONSTITUTION: An organic dye for a dye-sensitized solar cell comprises a material selected from a group consisting of a compound indicated in chemical formula 1 or 2. In chemical formula 1 and, x is a substituted or unsubstituted aromatic hydrocarbon group, Z is a substituted or unsubstituted heterocyclic group, A is a group comprising hydrogen-combinable acidic group(-COOH) as a linear or heterocyclic group. A dye-sensitized solar cell device comprises the organic dye.

Description

Novel Organic Dyes and Dye-Sensitized Solar Cells Comprising the Same {NOVEL ORGANIC DYES AND A DYE-SENSITIZED SOLAR CELL COMPRISING THE ORGANIC DYES}

The present invention relates to a novel dye-sensitized solar cell organic dye and a method for manufacturing the same, which has a higher absorbance than the conventional dye, exhibits improved Jsc (short-circuit photocurrent density) and photoelectric conversion efficiency can greatly improve the efficiency of the solar cell. .

Unlike other energy sources, solar cells are endlessly resource-friendly and environmentally friendly sources. Silicon solar cells, dye-sensitized solar cells, and the like are known.

Since silicon solar cells are quite expensive to manufacture, they are difficult to be commercialized, and there are many difficulties in improving battery efficiency. On the other hand, dye-sensitized solar cells have a significantly lower manufacturing cost than conventional silicon-based solar cells, and thus, there is a possibility of replacing conventional amorphous silicon solar cells. The dye-sensitized solar cell is a mechanism for generating electron-hole pairs by absorbing light energy of a visible light ray. The dye-sensitized solar cell is composed of a photo-electrochemical solar cell comprising a photosensitive dye molecule and a transition metal oxide Battery.

Currently, ruthenium metal dyes are known as practical dyes for dye-sensitized solar cells. These ruthenium dyes are not only expensive in production cost, low absorption coefficient, but also environmentally friendly. Recently, researches on the development of organic dyes which do not use metals have been focused on to solve these problems.

In general, organic dyes that do not use a metal complex are synthesized in a structure in which an electron donor and an electron acceptor are connected by a π-bond, and the electron donor is an aromatic amine derivative, and the electron acceptor is 2- Cyanoacrylic acid is most commonly used, and π-conjugates use thiophene or phenyl groups, and the long-wavelength or short-wavelength spectrum can be adjusted according to the length and conditions of the π-conjugates.

In general, organic dyes have much room for improvement due to their low light conversion efficiency, chemical instability, lack of adsorption with metal oxides, etc., compared with ruthenium metal dyes. Therefore, it is necessary to develop cheap organic dyes which can replace ruthenium metal dyes.

In order to solve the problems of the prior art, the present invention has introduced a two electron acceptor (electron acceptor) to improve the adsorption amount of the dye in the metal oxide to examine the photoelectric conversion efficiency, as well as one electron donor (electron donor) The present invention was completed by confirming that the functional group for preventing recombination with the electrolyte was introduced into the C) to improve the flow of electrons and exhibit high photoelectric conversion efficiency.

Accordingly, an object of the present invention is to synthesize organic dyes having electron donors and various functional groups and two or more electron acceptor functional groups in a molecule to improve photoelectric efficiency, and evaluate the performance of the synthesized compound in DSSC for dye-sensitized solar cells. It is to provide an organic dye suitable for application.

According to one embodiment of the present invention, there is provided a dye for a solar cell dye comprising a material selected from the group consisting of a compound represented by the following formula (1) or (2).

In Chemical Formulas 1 and 2, X is a substituted or unsubstituted aromatic hydrocarbon group, Z is a substituted or unsubstituted heterocyclic group, and A is a linear or heterocyclic group. Possible groups may be selected which include acidic groups (-COOH).

Specifically, X may be a substituted or unsubstituted aromatic hydrocarbon group selected from the group consisting of benzene, naphthalene, anthracene, phenanthrene and derivatives thereof.

More specifically, X is an aromatic compound containing an alkyl group and a vinyl group having 1 to 12 carbon atoms; And a phenyl group containing an alkyl group having 1 to 12 carbon atoms.

Specifically, Z may be selected from the group consisting of thiophene, furan, pyrrole and derivatives thereof, and A may be selected from the group consisting of 2-cyanoacrylic acid, rhodanine-3-acetic acid and derivatives thereof. .

According to an embodiment of the present invention, Chemical Formula 1 or 2 may be a compound represented by Chemical Formula 3 or 4.

In Chemical Formulas 3 and 4, R is an alkyl group having 1 to 12 carbon atoms or a vinyl group,

Y is sulfur (S), oxygen (O) or nitrogen (N),

또는

이고, A is

or

ego,

m and n are each an integer of 1 to 3,

Herein, when n is 2 or 3, it may be optionally connected to a vinyl group.

More preferably, the dye is a dye for a dye-sensitized solar cell comprising a compound having a structure represented by the following formula (5) to (12) and combinations thereof:

In Formulas 5 to 12, m and n are each an integer of 1 to 3.

Most preferably the dye may comprise a compound consisting of a compound having a structure of any one of the following structural formulas and combinations thereof:

,

.

,

.

In addition, according to another aspect of the invention, there is provided a dye-sensitized solar cell comprising the dye.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

The present invention not only prevents association behavior of organic dyes by introducing various functional groups including intramolecular linkage groups, but also functions as a blocking layer for preventing recombination of electrons and electrolytes transferred to TiO ₂ . By doing so, it is possible to maximize high Jsc (short-circuit photocurrent density) photoelectric conversion efficiency.

1 is an absorption spectrum of the DMF solution of compounds 13 and 14 used in the present invention.
2 is a current-voltage curve of a dye-sensitized solar cell according to an embodiment of the present invention.
3 is IPCE data showing photoelectric conversion efficiency at a unit wavelength of a dye-sensitized solar cell according to an embodiment of the present invention.

Example  1. Synthesis of Dyes

Two dyes were synthesized according to the above scheme. The structure of each product was analyzed using NMR (varian, 300MHz), and the redox properties of the dye were investigated using cyclic voltammety (Model: CV-BAS-Epsilon), and electrolyte. Dimethyl formamide (DMF) dried as a solution was used, and 0.1 M tetra butyl ammonium fluorophosphate (TBAPF6) was used as the electrolyte. Ag / AgCl and Pt wire (0.5 mm in diameter) electrodes were used as reference and counter electrodes, respectively. The scan speed was 100 mV / s. In order to measure the efficiency of the fabricated device was measured at 100 mW / cm ² using 81160 300W solar simulator (Oriel). In addition, photoelectric conversion efficiency (IPCE, incident photon to current efficiency, Peccell technology, model: PEC-L11) at unit wavelength for dye-sensitized solar cells was measured.

10- Phenyl -10H- Phenocyazine  (One):

Phenocyazine (3.29 g, 13.75 mmol), 1-iodobenzene (3 g, 16.5 mmol) and sodium tert-butoxide (1.04 g, 5.5 mmol) are sufficiently dissolved in 100 mL of toluene. After tritertbutylphosphine (8 g, 20.63 mmol) and Pd ₂ (dba) ₃ (0.5 g, 0.55 mmol) are added, the solution is sufficiently dissolved at room temperature under a nitrogen atmosphere, followed by stirring under reflux at 120 ° C. After the reaction is completed, work-up is performed on a solvent mixed with water and CHCl ₃ in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After the solvent was removed, a light yellow solid product (2.2g, 48%) was obtained through several times of recrystallization with methanol. ¹ H NMR (300 MHz, CDCl ₃ ): δ 7.42-7.39 (d, J = 7.2 Hz, 2H), 7.29-7.26 (t, J = 7.5 Hz, 2H), 7.01-6.98 (d, J = 8.7 Hz, 2H), 6.82 (m, 4H), 6.20 (m, 3H).

3,7- Dibromo -10- Phenyl -10H- Phenocyazine  (2):

10-phenyl-10H-phenocazine (1.5 g, 5.45 mmol) is dissolved in 10 mL of acetic acid, and then bromine water (1.91 g, 12 mmol) is slowly added dropwise at 0 ° C, followed by stirring for 12 hours. At the end of the reaction, titrate with sodium hydroxide saturated in water. After the titration, work-up is carried out in a solvent mixed with water and chloroform in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After removing the solvent, a red solid product (1.5g, 63.6%) was obtained through several recrystallization processes using methanol and dichloromethane. ¹ H NMR (300 MHz, CDCl ₃ ): δ 7.42-7.39 (d, J = 7.8 Hz, 2H), 7.22-7.19 (d, J = 7.8 Hz, 2H), 7.08 (s, 2H), 6.91-6.88 ( d, J = 8.4 Hz, 2H), 6.02-5.99 (dd, J = 8.4 Hz, 3H).

10- Phenyl -3,7-d die (Thiophen-2-yl) -10H- Phenocyazine  (3):

3,7-Dibromo-10-phenyl-10H-phenoxyazine (0.95 g, 2.1 mmol), tributyl-thiophen-2-yl-stain (2.03 g, 5.4 mmol) and PdCl ₂ (PPh) under nitrogen atmosphere ₃ ) ₂ (0.1 g, 0.13 mmol) is dissolved in 50 mL of dried tetrahydrofuran and stirred at reflux at 70 ° C. for 24 hours. After the reaction is completed, work-up is carried out in a solvent mixed with water and chloroform in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After removing the solvent, column chromatography (chloroform : Hexane, 1: 3) was used to obtain a yellow solid product (0.75 g, 81.5%). ¹ H NMR (300 MHz, CDCl ₃ ): δ 7.42-7.39 (d, J = 7.8 Hz, 2H), 7.22-7.19 (d, J = 7.8 Hz, 2H), 7.114 (m, 4H), 7.10 (t, J = 4.3 Hz, 2H), 7.08 (s, 2H), 6.91-6.88 (d, J = 8.4 Hz, 2H), 6.02-5.99 (dd, J = 8.4 Hz, 3H).

5,5 '-(10- Phenyl -10H- Phenocyazine -3,7-dyl) Dithiophene -2- Carbaaldehyde  (4):

10-phenyl-3,7-d di (thiophen-2-yl) -10H-phenosazine (0.72 g, 1.6 mmol) was dissolved in 15 mL of 1,2-dichloroethane and then dimethylformamide ( 0.3 g, 4.09 mmol) is added, and phosphorus oxychloride (0.62 g, 4.09 mmol) is slowly added dropwise at 0 ° C, followed by stirring under reflux for 8 hours. After the reaction is completed, work-up is carried out in a solvent mixed with water and chloroform in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After the solvent was removed, an orange solid product (0.5 g, 63.2%) was obtained using column chromatography (ethyl acetate: hexane, 1: 3). ¹ H NMR (300 MHz, CDCl ₃ ): δ 9.85 (s, 2H), 7.69-7.68 (d, J = 3.9 Hz, 4H), 7.53 (S, 2H), 7.45-7.44 (d, J = 7.8 Hz, 2H), 7.13-7.11 (d, J = 8.4 Hz, 4H), 6.18-6.15 (dd, J = 8.7 Hz, 3H).

Compound 13:

5,5 '-(10-phenyl-10H-phenocazine-3,7-diyl) dithiophene-2-carbaaldehyde (0.4 g, 0.807 mmol) and 2-cyanoacetate (0.34 g, 3.99 mmol ) And piperidine, dissolved in 20 mL of acetonitrile and stirred under reflux for 6 hours. After completion of the reaction, the solid produced in the reactor was filtered to obtain a dark red solid product (0.45 g, 88.5%). ¹ H NMR (300MHz, DMSO): δ 8.67 (s, 2H), 8.30 (s, 2H), 7.89-7.88 (d, J = 3.3 Hz, 2H), 7.64-7.63 (d, J = 3.3 Hz, 2H ), 7.60-7.58 (d, J = 7.8 Hz, 2H), 7.53 (s, 2H), 7.44-7.41 (d, J = 7.8 Hz, 2H), 7.35-7.33 (d, J = 8.4 Hz, 2H) , 6.20-6.17 (dd, J = 8.7 Hz, 3H).

10- (4- Hexylbenzene ) -10H- Phenocyazine  (5):

Phenocyazine (1.57 g, 7.87 mmol), 1-bromo-4-n-hexyl-benzene (1.86 g, 6.57 mmol) and sodium tert-butoxide (1.75 g, 9.2 mmol) are sufficiently dissolved in 20 mL of toluene. . After tritertbutylphosphine (0.208 g, 0.78 mmol) and Pd ₂ (dba) ₃ (0.2 g, 0.22 mmol) are added, the solution is sufficiently dissolved at room temperature under a nitrogen atmosphere, followed by stirring at reflux at 120 ° C. After the reaction is completed, work-up is carried out in a solvent mixed with water and chloroform in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After the solvent was removed, a light yellow solid product (1.5 g, 64%) was obtained through recrystallization several times with methanol. ¹ H NMR (300 MHz, CDCl ₃ ): δ 7.40-7.26 (m, 4H), 7.01-6.99 (d, J = 6.9 Hz, 2H), 6.83 (m, 4H), 6.19 (m, 2H), 2.73- 2.68 (t, J = 7.8 Hz, 2H), 1.71-1.65 (t, J = 6.3 Hz, 2H), 1.36-1.26 (m, 4H), 0.93-0.83 (m, 5H).

3,7- Bromo -10- (4- Hexylphenyl ) -10H- Phenocyazine  (6):

10- (4-hexylbenzene) -10H-phenocazine (0.7 g, 2 mmol) was dissolved in 10 mL of acetic acid, and then slowly dropwise bromine water (0.68 g, 4.28 mmol) was added at 0 ° C. and stirred for 12 hours. do. At the end of the reaction, titrate with sodium hydroxide saturated in water. After the titration, work-up is carried out in a solvent mixed with water and chloroform in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After the solvent was removed, a red solid product (1.0 g, 97%) was obtained through several recrystallization processes using methanol and dichloromethane. ¹ H NMR (300 MHz, DMSO): δ 7.50-7.18 (d, J = 7.8 Hz, 2H), 7.33-7.27 (m, 4H), 7.11-7.07 (dd, J = 2.1 Hz, 2H), 6.0 (d , J = 8.7 Hz, 2H), 2.71-2.66 (t, J = 7.8 Hz, 2H), 1.64 (m, 2H), 1.32 (m, 6H), 0.88 (m, 3H).

10- (4- Hexylphenyl ) -3,7-di (thiophen-2-yl) -10H- Phenocyazine  (7):

3,7-3,7-bromo-10- (4-hexylphenyl) -10H-phenocazine (1.5 g, 2.8 mmol) and tributyl-thiophen-2-yl-staine (2.38 g) under nitrogen atmosphere , 6.37 mmol) and PdCl ₂ (PPh ₃ ) ₂ (0.12 g, 0.17 mmol) were dissolved in 50 mL of dried tetrahydrofuran and stirred at reflux at 70 ° C. for 24 hours. After the reaction is completed, work-up is carried out in a solvent mixed with water and CHCl ₃ in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After removing the solvent, column chromatography (chloroform : Hexane, 1: 3) gave a yellow solid product (1.42 g, 95%). ¹ H NMR (300MHz, DMSO): δ 7.54-7.47 (dd, J = 8.1Hz, 4H), 7.40-7.32 (m, 6H), 7.20 (d, J = 2.1Hz, 2H), 7.12-7.09 (d , J = 3.9 Hz, 2H), 6.14-6.11 (d, J = 8.7Hz, 2H), 2.76-2.71 (t, J = 7.8Hz, 2H), 1.69-1.67 (m, 2H), 1.36 (m, 6H), 0.94 (m, 3H).

5,5 '-(10- (4- Hexylphenyl ) -10H- Phenocyazine -3,7- Dill ) Dithiophene -2- Carba Aldehy De (8):

Dissolve 10- (4-hexylphenyl) -3,7-di (thiophen-2-yl) -10H-phenosazine (1.3 g, 2.48 mmol) in 15 mL of 1,2-dichloroethane and then Methylformamide (0.453 g, 6.19 mmol) is added and phosphorus oxychloride (1.0 g, 6.52 mmol) is slowly added dropwise at 0 ° C. and stirred under reflux for 8 hours. After the reaction is completed, work-up is carried out in a solvent mixed with water and chloroform in a 1: 1 ratio. The organic layer which has undergone the work-up is separated by extraction and then the solvent is removed under reduced pressure. After the solvent was removed, an orange solid product (1.0 g, 69.6%) was obtained using column chromatography (ethyl acetate: hexane, 1: 3). ¹ H NMR (300MHz, DMSO): δ 9.88 (s, 2H), 7.44 (m, 2H), 7.34 (m, 4H), 7.19-7.17 (m, 6H), 5.93-5.90 (d, J = 8.4 Hz) , 2H), 2.76-2.71 (t, J = 7.8 Hz, 2H), 1.69-1.67 (m, 2H), 1.36 (m, 6H), 0.94 (m, 3H).

Compound 14:

5,5 '-(10- (4-hexylphenyl) -10H-phenoxyazine-3,7-diyl) dithiophene-2-carbaaldehyde (1.2 g, 2.0 mmol) and 2-cyanoacrylic acid ( cyanoacrylic acid) (0.9 g, 10.3 mmol) and piperidine are dissolved in 20 mL of acetonitrile and stirred under reflux for 6 hours. After completion of the reaction, the solid produced in the reactor was filtered to obtain a dark red solid product (0.6 g, 42.3%). ¹ H NMR (300 MHz, DMSO): δ 8.41 (s, 2H), 8.23 (s, 2H), 7.84 (m, 2H), 7.58 (d, J = 3.9 Hz, 2H), 7.55-7.48 (dd, J = 7.8 Hz, 4H), 7.40 (d, J = 7.8 Hz, 2H), 7.31-7.28 (d, J = 8.4 Hz, 2H), 6.13-6.10 (d, J = 7.8 Hz, 2H).

Example  2. Fabrication of Dye-Sensitized Solar Cells

Conductive glass substrates (FTO; TEC8, Pilkington, 8 Ω / cm 2, Thickness of 2.3 mm) were cleaned in ethanol using ultrasonic waves. A commercially prepared TiO ₂ paste (20 nm, solarnonix) was prepared, the prepared TiO ₂ paste was coated on a glass substrate which was previously cleaned using a doctor blade, and baked at 500 ° C. for 30 minutes. The thickness of the fired TiO ₂ paste layer was measured by Alpha-step IQ surface profiler (KLA Tencor). In order to use another TiO ₂ paste as a scattering layer, the calcined layer was recoated with 250 nm-sized TiO ₂ particles and then calcined at 500 ° C. for 30 minutes. The prepared TiO ₂ film was immersed in 0.04 M TiCl ₄ aqueous solution at 70 ° C for 30 minutes. For dye adsorption, the annealed TiO ₂ electrode was immersed in 0.3 mM dye solution at 50 ° C. for 3 hours. 2-propanol of 0.7 mM H ₂ PtCl that produced a ₆ solution at 400 ℃ through thermal reduction of 20 minutes to prepare the Pt counter electrode. The dye adsorbed TiO ₂ electrode and a Pt counter-electrode as a binder dissolved in 60㎛- Assembled using thick Surlyn (Dupont 1702). A liquid electrolyte was introduced through the perforation holes on the opposite electrode. Electrolyte was prepared by dissolving 3-propyl-1-methyl-imidazolyl iodide (PMII, 0.7M), lithium iodide (LiI, 0.2M), iodine dissolved in acetonitrile / valeronitrile (85:15) (I ₂ , 0.05M) and t-butylpyridine (TBP, 0.5M).

Ε is the molar extinction coefficient, E _ox Is the oxidation potential, E _{0 -O} is the voltage at the intersection of the absorption and emission spectra. The oxidation and reduction levels of the dyes were calculated using the equation HOMO (eV) =-4.5- (E _onset- E _{( Ferrocene )} ). The absorption spectra were measured in solution with dimethyl formamide (DMF).

In Table 2, N719 is a ruthenium-based dye used in a conventional dye-sensitized solar cell and has a structure as follows.

In Table 2, Jsc represents a short-circuit photocurrent density, Voc represents an opencircuit photovoltage, ff represents a fill factor, and η represents an overall photoconversion efficiency. At this time, the performance of the dye-sensitized solar cell was measured to a working area of 0.24 cm ² .

In the case of using the organic compound (Compound 13, Compound 14) according to an embodiment of the present invention it was confirmed that excellent photoelectric conversion efficiency can be obtained when using a ruthenium-based dye.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

Claims (8)

Dye-sensitized solar cell dye comprising a material selected from the group consisting of a compound represented by the following formula (1) or (2):
[Formula 1]

(2)

In Chemical Formula 1 and Chemical Formula 2,
X is a substituted or unsubstituted aromatic hydrocarbon group,
Z is a substituted or unsubstituted heterocyclic group,
A is a group containing an acid group (-COOH) capable of hydrogen bonding as a linear or heterocyclic group. The method of claim 1,
X is a dye for a dye-sensitized solar cell, characterized in that the substituted or unsubstituted aromatic hydrocarbon group selected from the group consisting of benzene, naphthalene, anthracene, phenanthrene and derivatives thereof. The method of claim 1,
X is an aromatic compound including an alkyl group and a vinyl group having 1 to 12 carbon atoms; And a phenyl group containing an alkyl group having 1 to 12 carbon atoms. The dye for a dye-sensitized solar cell, characterized in that the aromatic hydrocarbon group selected from the group consisting of. The method of claim 1,
Z is selected from the group consisting of thiophene, furan, pyrrole and derivatives thereof,
A is a dye for a dye-sensitized solar cell, characterized in that selected from the group consisting of 2-cyanoacrylic acid, rhodanine-3-acetic acid and derivatives thereof. The method of claim 1,
Formula 1 and Formula 2 is a dye-sensitized solar cell dye comprising a derivative represented by the following formula (3) or (4):
(3)

[Chemical Formula 4]

In Chemical Formulas 3 and 4,
R is an alkyl or vinyl group having 1 to 12 carbon atoms,
Y is sulfur (S), oxygen (O) or nitrogen (N),
A is

or

ego,
m and n are each an integer of 1 to 3,
Here, when n is 2 or 3 can be optionally connected to a vinyl group. 6. The method of claim 5,
The dye is a dye for a dye-sensitized solar cell comprising a material selected from the group consisting of a compound having a structure of the formula 5 to 12 and combinations thereof:
[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

[Chemical Formula 9]

[Formula 10]

(11)

[Chemical Formula 12]

Here, m and n in the formulas 5 to 12 are each an integer of 1 to 3. The method according to claim 6,
The dye dye-sensitized solar cell dye comprising a compound having a structure of any one of the following structural formula and combinations thereof:

. A dye-sensitized solar cell device comprising the dye for a dye-sensitized solar cell according to any one of claims 1 to 7.

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