KR20080019669A - Phenothiazine-containing dyes for dye-sensitized solar cells - Google Patents

Abstract

A phenothiazine-containing dye for a dye-sensitized solar cell is provided to realize high light absorptivity, thereby improving photoelectric conversion efficiency to a dye-sensitized solar cell. A phenothiazine-containing dye for a dye-sensitized solar cell is represented by the following formula 1. In formula 1, each of X and Y independently represents a substituted or non-substituted aromatic hydrocarbon group, substituted or non-substituted aromatic heterocyclic group or a combination thereof, wherein at least one of X and Y is phenothiazinyl group or phenothiazinylvinylaryl group; Z is a substituted or non-substituted aromatic hydrocarbon group, substituted or non-substituted heterocyclic group, vinyl, substituted or non-substituted polyvinyl group; and A is an acidic group.

Description

Phenothiazine-containing dyes Dye-sensitized solar cells {Phenothiazine-containing dyes for Dye-Sensitized Solar Cells}

The present invention relates to a dye used in a dye-sensitized solar cell and a dye-sensitized solar cell using the same, and more particularly, to prepare a phenothiazine-containing dye having a high light absorption and apply it to a light absorbing layer for solar cells photoelectric current conversion It relates to a dye which can improve the efficiency and increase the open voltage.

Recently, various studies have been conducted to replace existing fossil fuels in order to reduce the emission of carbon dioxide which is the main cause of global warming and to solve the energy problem. Extensive research to harness natural energy such as wind, nuclear power, and solar power has been conducted to replace petroleum resources that will be exhausted in the near future. Among these, solar cells using solar energy are the most environmentally friendly, Unlike other energy sources, resources can be infinite if we only develop appropriate methods of use. Since solar cells using selenium (Se) were developed in 1983, silicon solar cells have been in the spotlight in recent years, but they are limited in practical use because they are very expensive in terms of manufacturing cost, and battery efficiency is still quite insufficient. In order to overcome this problem, the development of low-cost dye-sensitized solar cells has been actively studied by various groups.

Dye-sensitized solar cells, instead of the electrical energy used in the organic electroluminescent display (OLED) driving mechanism, are a mechanism that absorbs the light energy of visible light and generates electron-hole pairs. It is a photoelectrochemical solar cell whose main component material is a transition metal oxide which transfers electrons. A dye-sensitized solar cell using nanoparticle titanium oxide, developed in 1991 by Michael Graetzel of the Swiss National Institute of Advanced Technology (EPFL), is a representative example of conventional dye-sensitized solar cells.

The dye-sensitized solar cells developed by them have the advantage that they can be applied to building exterior glass windows or glass greenhouses due to the transparent electrodes and are cheaper to manufacture than conventional silicon solar cells, but they are limited in practical applications due to their low photoelectric conversion efficiency. .

The photoelectric current conversion efficiency is proportional to the amount of electrons generated by the absorption of sunlight. In order to increase the efficiency of solar cells, it is possible to increase the absorption of sunlight or increase the amount of dye adsorbed in an appropriate way to generate more electrons or to prevent the generated exciton from being dissipated by electron-hole recombination. Can also give In order to increase the absorption of sunlight, it is possible to increase the reflectance of the platinum electrode or to manufacture the particles of the oxide semiconductor to nanometer size to increase the adsorption amount of the dye per unit area. Methods have been developed. However, such a conventional method has a limitation in improving the photoelectric conversion efficiency of the solar cell, and therefore, a new technology for improving the efficiency, in particular, the development of a new dye having high photoelectric conversion efficiency is urgently required.

An object of the present invention is to provide a dye for a dye-sensitized solar cell exhibiting a high light absorption, to provide a dye-sensitized solar cell with improved photoelectric conversion efficiency comprising the dye.

In order to achieve the above object, the present invention provides a dye for a dye-sensitized solar cell comprising a compound having the structure of formula (1).

In the above formula,

X and Y are each independently a substituent consisting of a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group and a combination thereof, wherein at least one is a phenothiazinyl group or a phenothiazinyl vinylaryl group , Z is a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a vinyl group, a substituted or unsubstituted polyvinyl group, and A is an acidic functional group.

In addition, the present invention provides a dye-sensitized solar cell comprising the dye.

Hereinafter, the present invention will be described in more detail.

The first step in driving a solar cell in a dye-sensitized solar cell is the process of generating a photo charge from the light energy. Typically, a dye material is used for generating a photo charge, and the dye material is excited by absorbing light transmitted through the conductive transparent substrate.

As the dye material, metal complexes are widely used. Among the metal complexes, mono, bis, or tris (substituted 2,2'-bipyridine) complex salts of ruthenium are generally used. However, they have a problem in that the efficiency of the electrons excited by light in the bottom state of the metal composite falls back to the ground state is relatively high, resulting in low efficiency. In order to solve this problem, many cases have been reported in which various electron transfer materials are introduced into a metal composite through covalent bonds. However, the introduction of electron transfer materials through covalent bonds has a problem that the process is very complicated and difficult to introduce various electron transfer materials.

In contrast, in the present invention, by preparing and using a dye of a compound having a phenothiazinyl group introduced in the aniline structure, the photoelectric current conversion efficiency of the dye-sensitized solar cell can be improved.

More specifically, the dye-sensitized solar cell dye of the present invention comprises a compound of formula (1).

[Formula 1]

In the above formula,

X and Y are each independently a substituent consisting of a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group and a combination thereof, wherein at least one is a phenothiazinyl group or a phenothiazinyl vinylaryl group , Z is a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a vinyl group, a substituted or unsubstituted polyvinyl group, and A is an acidic functional group.

In the compound of the formula, X and Y are each independently a substituted or unsubstituted aromatic hydrocarbon group of 5 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group and a combination thereof, at least one of the pheno Thiazinyl group or phenothiazinyl vinylaryl group.

The aromatic hydrocarbon group may include a substituent consisting of benzene, naphthalene, anthracene, fluorene, biphenyl, and combinations thereof.

In addition, the heterocyclic group is preferably selected from a substituent consisting of pyran, pyrrole, thiophene, carbazole and combinations thereof.

X and Y may also include a substituent consisting of alkyl, alkoxy, aryl group, alkenyl group, arylene group, alkylene group, and combinations thereof.

In the substituent, the alkyl group is preferably selected from a substituent consisting of a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms.

The alkoxy group is preferably selected from a substituent consisting of an oxygen-containing substituted or unsubstituted alkoxy group having an alkyl group having 1 to 20 carbon atoms.

The aryl group may be used alone or in combination, carbocyclic aromatic compound having 6 to 30 carbon atoms containing one or more rings, such as phenyl, naphthyl, tetrahydronaphthyl, indan or biphenyl compound).

The alkylene group has the form of a radical to which both ends of the alkyl group can be bonded, wherein the alkyl group is as defined above.

In Chemical Formula 1, Z is preferably selected from a substituent consisting of a vinyl group, a polyvinyl group, benzene, naphthalene, anthracene, fluorene, biphenyl, pyran, pyrrole, thiophene, carbazole, and combinations thereof. .

In addition, Z may also include a substituent selected from the group consisting of alkyl, alkoxy, aryl group, alkenyl group, arylene group, alkylene group and combinations thereof as in X and Y. The substituents are the same as described above for X and Y.

A is an acidic functional group. Specifically, A is preferably selected from a substituent consisting of a carboxyl group, a phosphorous acid group, a sulfonic acid group, a phosphinic acid group, a hydroxy group, an oxycarboxylic acid, an acid amide, and a combination thereof, and more preferably a carboxyl group.

In addition, in the formula 1, at least one of X and Y is a substituted or unsubstituted phenothiazinyl group or phenothiazinyl vinylaryl group, preferably all substituted or unsubstituted phenothiazinyl group or pheno It is a thiazinyl vinyl aryl group.

Most preferably, the dye may include a compound having a structure of any one of the following structural formulas and a combination thereof.

[Formula 2]

R=C₁~C₁₈ 인 알킬기

Alkyl group having R = C ₁ ~ C ₁₈

[Formula 3]

R=C₁~C₁₈ 인 알킬기

Alkyl group having R = C ₁ ~ C ₁₈

[Formula 4]

R=C₁~C₁₈ 인 알킬기, R₁=C₀~C₈ 인 알킬기, n=1~3

An alkyl group having R = C ₁ to C ₁₈ , an alkyl group having R ₁ = C ₀ to C ₈ , n = 1 to 3

[Formula 5]

R=C₁~C₁₈ 인 알킬기, R₁=C₀~C₈ 인 알킬기, n=1~3

An alkyl group having R = C ₁ to C ₁₈ , an alkyl group having R ₁ = C ₀ to C ₈ , n = 1 to 3

[Formula 6]

R=C₁~C₁₈ 인 알킬기

Alkyl group having R = C ₁ ~ C ₁₈

[Formula 7]

R=C₁~C₁₈ 인 알킬기

Alkyl group having R = C ₁ ~ C ₁₈

[Formula 8]

R=C₁~C₁₈ 인 알킬기

Alkyl group having R = C ₁ ~ C ₁₈

The dye for a dye-sensitized solar cell of the present invention has a high light absorption, and can be applied to the light absorption layer for solar cells to improve photoelectric current conversion efficiency and increase an open voltage.

The synthesis process of the phenothiazine-containing dye of Chemical Formula 3 according to the present invention is represented as follows.

[Formula 9] [Formula 10] [Formula 11]

 [Formula 12] [Formula 13] [Formula 14] [Formula 15]

[Formula 15] [Formula 11] [Formula 16]

                          [Formula 3]

In which R is as defined. The dye represented by Chemical Formula 3 has a light absorbance of 70,000 dm ³ mol ^-1 cm ^-1 or more, which is significantly higher than that of conventional dyes. This high absorbance is an important parameter in improving the photoelectric conversion efficiency of the solar cell, it is considered that the application possibility is high when applied to the device for dye-sensitized solar cell. Specific examples represented by the formula (3) are as follows. However, the present invention is not limited to the structure illustrated below.

[Formula 3a]

Example 1 Preparation of Formula 11

Step 1:

Step 2:

Example 2 Preparation of Chemical Formula 15

Step 1:

Step 2:

Step 3:

Example 3 Preparation of Chemical Formula 3a

Step 1:

Step 2:

Example 4 Fabrication of Dye-Sensitized Solar Cells

Manufacture of Dye-Sensitized Solar Cell

(1) working electrode fabrication

Cut the FTO glass (Fluorine-doped tin oxide coated conduction glass, Pilkington, TEC7) into 1.5 cm x 1.5 cm and wash the sonication with soapy water for 5 minutes and then completely remove the soapy water. After that, repeat sonication washing with ethanol three times for 5 minutes. After that, rinse thoroughly with Anhydrous ethanol and dry in oven. In order to improve the contact force with TiO ₂ on the prepared FTO glass, 0.2M Titanium (IV) butoxide solution was coated by spin coating method, and the solvent was completely dried in an oven.

Afterwards, Dyesol titania (TiO ₂ ) is coated on the FTO glass by the doctor blade technique. The coated film was dried in a 100 ^o C oven for 10 minutes and then heat treated at 450 ^o C for 30 minutes to form a 10 micrometer thick TiO ₂ Get a film. TiO ₂ after heat treatment The dye can be adsorbed by soaking the film in an anhydrous ethanol solution of the synthesized dye at 0.5 mM concentration for 24 hours (if a dye is not dissolved in anhydrous ethanol, use a solvent that can dissolve). After the adsorption is completed, completely wash the dye that has not been adsorbed with anhydrous ethanol and dry it. The dye-adsorbed film is scraped off, leaving only the size of 4 mm x 4 mm.

(2) counter electrode fabrication

Using a diamond drill (Bosch, Dremel multipro395), drill two holes into the electrolyte into a 1.5 cm by 1.5 cm FTO glass. Thereafter, it is washed and dried in the same manner as the washing method described above. Then, hydrogen hexachloroplatinate (H ₂ PtCl ₆ ) 2-propanol solution is coated on FTO glass and heat-treated at 450 ^o C for 30 minutes.

(3) Sandwich cell production

Surlyn (Solaronix, SX1170-25 Hot Melt) was cut into rectangular bands between the working and counter electrodes and the two electrodes were joined together using a hot press. The electrolyte was injected through two small holes in the counter electrodes. After that, make sandwich cell by sealing with Surlyn strip and cover glass. The electrolyte solution was prepared by using 0.1 M LiI, 0.05 MI ₂ , 0.6 M 1-hexyl-2,3-dimethylimidazolium iodide and 0.5 M 4- tert -butylpyridine as 3-metoxypropionitrile solvents.

(4) Photocurrent-voltage measurement

The sandwich cell prepared above was irradiated with Xe lamp (Oriel, 300 W Xe arc lamp) equipped with AM 1.5 solar simulating filter to obtain current-voltage curve using M236 source measure unit (SMU, Keithley). The electric potential ranged from -0.8 V to 0.2 V, and the light intensity was 100 mW / cm ² .

[Formula 3a]

A dye-sensitized solar cell was prepared using a compound having the structure of Chemical Formula 3a as a dye.

As a result of testing the performance of the solar cell fabricated as described above, the open voltage (Voc) was 0.73V and the current flow was confirmed in Example 4. In particular, the photoelectric conversion efficiency recorded 74% of the standard comparative compound N719. It was. Figure 2 shows the absorption wavelength of the ultraviolet-visible region of the compound having the structure of formula 3a, the absorbance is 70,000 dm ³ mol ^-1 cm ^-1 or more, which is significantly higher than the conventional dye. Such high absorbance becomes an important parameter in improving the photoelectric conversion efficiency of solar cells.

1 is a schematic view showing a dye-sensitized solar cell according to Example 4 of the present invention.

2 is an ultraviolet-visible light absorption wavelength according to the dye of Example 4. FIG.

Claims (8)

Dye-sensitized solar cell dye having a structure of formula (1). [Formula 1]

Wherein X and Y are each independently a substituent consisting of a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, and a combination thereof, wherein at least one is a phenothiazinyl group or phenothiazinyl vinyl An aryl (phenothiazinylvinylaryl) group, Z is a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a vinyl group, a substituted or unsubstituted polyvinyl group, and A is an acidic functional group. The method of claim 1, X and Y are each independently a substituted or unsubstituted aromatic hydrocarbon group of 5 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group and a combination thereof, wherein at least one of X and Y is a pheno Dye for dye-sensitized solar cells, which is a thiazinyl group or a phenothiazinyl vinylaryl group. The method of claim 1, X and Y are dyes for dye-sensitized solar cells comprising a substituent selected from the group consisting of alkyl, alkoxy, aryl group, arylene group, alkylene group and combinations thereof. The method of claim 1, Z is a dye-sensitized embodiment comprising a substituent selected from the group consisting of vinyl group, polyvinyl group, benzene, naphthalene, anthracene, fluorene, biphenyl, pyran, pyrrole, thiophene, carbazole and combinations thereof Battery dyes. The method of claim 1, Z is a dye for a dye-sensitized solar cell is a substituent selected from the group consisting of alkyl, alkoxy, aryl group, alkenyl group, arylene group, alkylene group and combinations thereof. The method of claim 1, A is a dye for a dye-sensitized solar cell comprising a substituent selected from the group consisting of carboxyl groups, phosphorous acid groups, sulfonic acid groups, phosphinic acid groups, hydroxy groups, oxycarboxylic acids, acid amides and combinations thereof. The method of claim 1, The dye is a dye for a solar-sensitized dye comprising a compound having a structure of the formula 2 to 8 and combinations thereof. [Formula 2]

Alkyl group having R = C ₁ ~ C ₁₈ [Formula 3]

Alkyl group having R = C ₁ ~ C ₁₈ [Formula 4]

An alkyl group having R = C ₁ to C ₁₈ , an alkyl group having R ₁ = C ₀ to C ₈ , n = 1 to 3 [Formula 5]

An alkyl group having R = C ₁ to C ₁₈ , an alkyl group having R ₁ = C ₀ to C ₈ , n = 1 to 3 [Formula 6]

Alkyl group having R = C ₁ ~ C ₁₈ [Formula 7]

Alkyl group having R = C ₁ ~ C ₁₈ [Formula 8]

Alkyl group having R = C ₁ ~ C ₁₈ A dye-sensitized solar cell device using the dye according to claim 1.

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