KR20070102821A - Photosensitizer for photovoltaic cell, and photovoltaic cell prepared from same - Google Patents

Abstract

Dye for a dye-sensitized photovoltaic cell and a photovoltaic cell manufactured by the same are provided to increase an open-circuit voltage by applying the dye to an optical absorption layer. A photovoltaic cell(10) manufactured by the dye for a dye-sensitized solar cell includes a first electrode(11), an optical absorption layer(12), a second electrode(14), and an electrolyte layer(13). The first electrode(11) includes a conductive transparent substrate. The optical absorption layer(12) is formed on one surface of the first electrode(11). The second electrode(14) faces the first electrode(11) where the optical absorption is formed. The electrolyte layer(13) is located between the first electrode(11) and the second electrode(14). The optical absorption layer(12) includes a semiconductor elementary particles. The conductive transparent substrate is a glass substrate or a plastic substrate including one of ITO(Indium Tin Oxide), FTO(Fluorine Tin Oxide), ZnO-(Ga2O3 or Al2O3), and TIN based oxidation and a mixed group thereof.

Description

Dye-sensitized solar cell dyes and dye-sensitized solar cells produced therefrom {PHOTOSENSITIZER FOR PHOTOVOLTAIC CELL, AND PHOTOVOLTAIC CELL PREPARED FROM SAME}

1 is a schematic diagram schematically showing a dye-sensitized solar cell according to an embodiment of the present invention.

Figure 2 is a graph showing the change in photoelectric yield (IPCE: Incident photon to Current Efficiency) at the unit wavelength for the dye-sensitized solar cells of Example 1 and Example 3.

<Explanation of symbols for main parts of the drawings>

10: dye-sensitized solar cell, 11: first electrode,

12: light absorption layer, 13: electrolyte layer,

14: second electrode

[Industrial use]

The present invention relates to a dye for a dye-sensitized solar cell and a dye-sensitized solar cell prepared therefrom, and more particularly, a dye that can improve the photoelectric current conversion efficiency of a solar cell and increase an open voltage, and employs the same. An improved dye-sensitized solar cell is disclosed.

[Private Technology]

Recently, various researches have been conducted to replace existing fossil fuels to solve the energy problem. In particular, extensive research has been conducted to utilize natural energy such as wind, nuclear power, and solar power to replace petroleum resources that will be exhausted within decades. Unlike other energy sources, solar cells using solar energy have unlimited resources and are environmentally friendly, so silicon solar cells have been in the spotlight recently since the development of Se solar cells in 1983.

However, such a silicon solar cell is very expensive to manufacture, and therefore, it is difficult to be commercialized, and there are many difficulties in improving battery efficiency. In order to overcome this problem, the development of dye-sensitized solar cells with significantly lower manufacturing costs has been actively studied.

Dye-sensitized solar cells, unlike silicon solar cells, contain photosensitive dye molecules capable of absorbing visible light to produce electron-hole pairs, and transition metal oxides that deliver the generated electrons as the main constituent material. Is a photoelectrochemical solar cell. Among the conventional dye-sensitized solar cells, a dye-sensitized solar cell using nanoparticle titanium oxide (anatase) developed by Michael Gratzel of the Swiss National Lausanne Institute of Advanced Technology (EPFL) in 1991 was developed. have.

This dye-sensitized solar cell has the advantages of being cheaper to manufacture than conventional silicon solar cells and applicable to glass windows or glass greenhouses for building exterior walls due to the transparent electrode, but the photoelectric conversion efficiency is low, and thus there is a limit in actual application. .

Since the photoelectric conversion efficiency of the solar cell is proportional to the amount of electrons generated by the absorption of sunlight, in order to increase the efficiency, the production of electrons may be increased by increasing the absorption of sunlight or by increasing the adsorption amount of the dye, or The generated exciton may be prevented from disappearing by electron-hole recombination.

In order to increase the amount of dye adsorption per unit area, particles of oxide semiconductor should be manufactured in the size of nanometer, and method of manufacturing by increasing the reflectance of platinum electrode or mixing several micro-sized semiconductor oxide light scatterers to increase the absorption of sunlight. Etc. have been developed. However, the conventional method has a limitation in improving the photoelectric conversion efficiency of the solar cell, and thus, there is an urgent demand for the development of a new technology for improving the efficiency.

It is an object of the present invention to provide a dye for a dye-sensitized solar cell exhibiting a high open voltage.

It is still another object of the present invention to provide a dye-sensitized solar cell including the dye and having improved photoelectric efficiency.

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):

[Formula 1]

(In Formula 1,

A and B are each independently selected from the group consisting of substituted or unsubstituted aromatic hydrocarbons, substituted or unsubstituted heterocycles, and combinations thereof, wherein at least one of A and B is a fluorenyl group Is,

D is selected from the group consisting of a vinyl group, a substituted or unsubstituted polyvinyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, and a combination thereof,

E is an acidic functional group.)

The present invention also includes a first electrode including a conductive transparent substrate, a light absorbing layer formed on one surface of the first electrode, a second electrode disposed to face the first electrode on which the light absorbing layer is formed, and the first electrode; It includes an electrolyte located between the second electrode, the light absorbing layer provides a dye-sensitized solar cell comprising the semiconductor fine particles and the dye.

Unless otherwise specified, in the present specification, 'alkyl group' means an alkyl group having 1 to 20 carbon atoms, 'aryl group' means an aryl group having 6 to 30 carbon atoms, and 'aryloxy group' means an aryloxy group having 6 to 30 carbon atoms. , 'Arylene group' is an arylene group having 6 to 30 carbon atoms. The "alkylene group" is an alkylene group having 1 to 20 carbon atoms, the "alkyleneoxy group" is an alkyleneoxy group having 1 to 20 carbon atoms, the "alkoxy group" is an alkoxy group having 1 to 20 carbon atoms, and the "alkylthio group" is carbon An alkylthio group having 1 to 20 and an 'aryleneoxy group' means an aryleneoxy group having 6 to 30 carbon atoms.

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

In dye-sensitized solar cells, the first step in driving solar cells is the process of generating photocharges from light energy. Typically, a dye material is used to generate photocharges, 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 complex 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 fluorenyl functional group introduced in place of an alkyl substituent in the aniline structure, the photoelectric efficiency of the dye-sensitized solar cell can be improved.

More specifically, the dye for solar cells according to one embodiment of the present invention comprises a compound of formula (I):

[Formula 1]

(In Formula 1,

A and B are each independently selected from the group consisting of substituted or unsubstituted aromatic hydrocarbons, substituted or unsubstituted heterocycles, and combinations thereof, wherein at least one of A and B is a fluorenyl group ego,

D is selected from the group consisting of a vinyl group, a substituted or unsubstituted polyvinyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, and a combination thereof,

E is an acidic functional group.)

In the compound of Formula 1, A and B are each independently selected from the group consisting of a substituted or unsubstituted aromatic hydrocarbon group having 5 to 20 carbon atoms, a substituted or unsubstituted heterocycle, and a combination thereof. , At least one of A and B is a fluorenyl group.

The aromatic hydrocarbon group may include one selected from the group consisting of benzene, naphthalene, anthracene, pyrene, phenanthrene, indene, perylene, fluorene, biphenyl, terphenyl, and combinations thereof.

In addition, the heterocyclic groups include pyridine, pyrazine, pyrimidine, pyrazole, pyrazolidine, pyran, pyrrole, benzoimidazole, imidazoline, imidazolidine, imidazole, pyrazole, triazole, triazine, diaz It is preferably selected from the group consisting of sol, morpholine, thiophene, thiazole, benzothiazole, naphthothiazole, benzoxazole, naphthooxazole, pyrazine, quinoline, quinazoline, carbazole and combinations thereof.

In addition, A and B are hydroxy, alkyl, halo, haloalkyl, nitro, cyano, alkoxy, alkylamino, aryl group, alkylthio group, ether group, thioether group, amino group, aryleneoxy group, alkenyl group, aryl It may also include a substituent selected from the group consisting of an oxy group, an arylene group, an alkylene group, an alkyleneoxy group, and a combination thereof.

In the substituent, the alkyl group is preferably selected from the group consisting of substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, more preferably selected from the group consisting of substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms. Can be. Even more preferably, the alkyl group has 1 to 6 carbon atoms including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, iso-amyl, hexyl, and the like. It is lower alkyl group of, Most preferably, it is a C1-C3 lower alkyl group.

The alkoxy group is selected from the group consisting of an oxygen-containing substituted or unsubstituted alkoxy group having an alkyl group having 1 to 20 carbon atoms, more preferably methoxy, ethoxy, propoxy, butoxy or t-butoxy. It is a C1-C6 lower alkoxy group. The alkoxy group also includes a haloalkoxy group substituted with one or more halogen atoms such as fluoro, chloro or bromo. More preferably haloalkoxy radicals having 1 to 3 carbon atoms, such as fluoromethoxy, chloromethoxy, trifluoromethoxy, trifluoroethoxy, fluoroethoxy or fluoropropoxy.

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), and the rings can be attached or fused together in a pendant manner. More preferably, the aryl group is a phenyl group. In addition, the aryl group more preferably has 1 to 3 substituents selected from the group consisting of hydroxy, halo, haloalkyl, nitro, cyano, alkoxy, lower alkylamino having 1 to 6 carbon atoms, and a combination thereof.

The alkylthio group means alkyl-S-, and the definition for the alkyl is as described above. More preferably, the alkylthio group includes a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms.

The amino group is selected from the group consisting of substituted or unsubstituted amino groups, more preferably N-methylamino group, N-ethylamino group, N, N-diethylamino group, N, N-diisoflophylamino group, N, N-dibutylamino group, N-benzylamino group, N, N-dibenzylamino group, N-phenylamino group, N-phenyl-N-methylamino group, N, N-diphenylamino group, N, N-bis (m-tolyl ) Amino group, N, N-bis (p-tolyl) amino group, N, N-bis (p-phenylyl) amino group, bis [4- (4-methyl) biphenyl] amino group, NN-biphenyl-N A substituted amino group having 1 to 30 carbon atoms such as -phenylamino group, N-α-naphthyl-N-phenylamino group, N-β-naphthyl-N-phenylamino group, and N-phenanthryl-N-phenylamino group have.

The aryleneoxy group means arylene-O-, wherein arylene is in the form of a radical to which both ends of the aryl group can be bonded, wherein the aryl group is as defined above.

The aryloxy group means aryl-O-, where aryl is as defined above.

The arylene is in the form of a radical to which both ends of the aryl group can be bonded, wherein the aryl group is as defined above.

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.

The alkyleneoxy group means alkylene-O-, wherein alkylene is as defined above.

In Chemical Formula 1, D is a vinyl group, polyvinyl group, benzene, naphthalene, anthracene, pyrene, phenanthrene, indene, perylene, fluorene, biphenyl, terphenyl, pyridine, pyrazine, pyrimidine, pyrazole, Pyrazolidine, pyran, pyrrole, benzoimidazole, imidazoline, imidazolidine, imidazole, pyrazole, triazole, triazine, diazole, morpholine, thiophene, thiazole, benzothiazole, naph It is preferably selected from the group consisting of tothiazole, benzoxazole, naphthooxazole, pyrazine, quinoline, quinazoline, carbazole and combinations thereof.

In addition, D is the same as in A and B, hydroxy, alkyl, halo, haloalkyl, nitro, cyano, alkoxy, alkylamino, aryl group, alkylthio group, ether group, thioether group, amino group, aryleneoxy group It may also include a substituent selected from the group consisting of alkenyl group, aryloxy group, arylene group, alkylene group, alkyleneoxy group and combinations thereof. The substituents are the same as described above for A and B.

E is an acidic functional group. Specifically, E is preferably 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, boric acid groups, squaric acid groups, and combinations thereof. Preferably carboxyl.

In addition, the dye in Formula 1, at least one of A and B is a substituted or unsubstituted fluorenyl group, preferably A and B are both substituted or unsubstituted fluorenyl group,

또는

이며,D is

or

Is,

R ₁ to R ₅ are each independently hydroxy, alkyl, halo, haloalkyl, nitro, cyano, alkoxy, alkylamino, aryl group, alkylthio group, ether group, thioether group, amino group, aryleneoxy group, Alkenyl group, aryloxy group, arylene group, alkylene group, alkyleneoxy group and combinations thereof, m, n, p and q are integers of 0 or 4, o and s is 1 Or 2

It is more preferable that E is a carboxy group.

Most preferably, the dye may include one selected from the group consisting of a compound having a structure of Formulas 2 to 5 and combinations thereof:

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

The dye-sensitized solar cell dye is applied to a light absorbing layer for a solar cell by introducing a fluorenyl functional group instead of an alkyl substituent in the aniline structure to improve photoelectric current conversion efficiency and increase an open voltage.

The present invention also provides a dye-sensitized solar cell comprising the dye.

In more detail, the dye-sensitized solar cell includes a first electrode including a conductive transparent substrate, a light absorbing layer formed on one surface of the first electrode, and a second electrode disposed to face the first electrode on which the light absorbing layer is formed. And an electrolyte positioned between the first electrode and the second electrode, wherein the light absorption layer includes semiconductor fine particles and the dye.

1 is a cross-sectional view schematically showing the structure of a dye-sensitized solar cell according to an embodiment of the present invention.

Referring to FIG. 1, the dye-sensitized solar cell 10 has a sandwich structure in which two transparent plate electrodes (the first electrode 11 and the second electrode 14) are bonded to each other. One of the transparent electrodes 11 has a light absorbing layer 12 formed on one surface of the transparent electrode 11 facing the counter electrode 14, and the light absorbing layer 12 is absorbed by the semiconductor fine particles and the semiconductor fine particles. A photosensitive dye is included in which electrons are excited by visible light absorption. The space between these two electrodes is filled with the redox electrolyte 13.

When sunlight enters the dye-sensitized solar cell 10, the photons are first absorbed by the dye molecules in the light absorbing layer 12, whereby the dye molecules electron-transfer from the ground state to the excited state to form electron-hole pairs. Electrons in the excited state are injected into the conduction band of the semiconductor fine particle interface, and the injected electrons are transferred to the first electrode 11 through the interface. After that, it moves to the second electrode 14 as a counter electrode through an external circuit. On the other hand, the dye oxidized as a result of the electron transfer is reduced by ions of the redox couple in the electrolyte layer 13, and the oxidized ions reach the interface of the second electrode 14 to achieve charge neutrality. The dye-sensitized solar cell is operated by a reduction reaction with one electron.

As the first electrode 10, any conductive transparent substrate having conductivity and transparency may be used without particular limitation. Specifically, the conductive transparent substrate may include indium tin oxide (ITO), fluorine tin oxide (FTO), ZnO- (Ga ₂ O ₃ or Al ₂ O ₃ ), tin oxide, and Glass substrates or plastic substrates containing materials selected from the group consisting of these combinations can be used.

In addition, specific examples of the plastic substrate include polyethylene terephthalate (poly) and polyethylene naphthalate (PEN), polycarbonate (PC), and polypropylene (PP). , Polyimide (PI), triacetyl cellulose (TAC), and the like.

As the conductive transparent substrate, it is more preferable to use SnO ₂ having excellent conductivity, transparency, and heat resistance, or a glass substrate containing ITO which is inexpensive in terms of cost.

In addition, the conductive transparent substrate may be doped with a material selected from the group consisting of Ti, In, Ga, Al, and combinations thereof.

The light absorbing layer 12 includes semiconductor fine particles and a dye according to an embodiment of the present invention in which electrons are excited by absorption of visible light by being absorbed by the semiconductor fine particles.

The semiconductor fine particles may be a metal oxide or a composite metal oxide having a perovskite structure, in addition to the single semiconductor represented by silicon. The semiconductor is preferably an n-type semiconductor in which conduction band electrons become carriers under photo excitation to provide an anode current. Specifically, the semiconductor fine particles include Si, TiO ₂ , SnO ₂ , ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ , and the like, and more preferably, anatase TiO ₂ may be used. The kind of the semiconductor is not limited to these, and these may be used alone or in combination of two or more thereof.

In addition, the semiconductor fine particles preferably have a large surface area in order for the dye adsorbed on the surface to absorb more light. Accordingly, the semiconductor fine particles preferably have an average particle diameter of 50 nm or less, and more preferably, may have an average particle diameter of 15 to 25 nm. When the particle diameter exceeds 50 nm, the surface area is small, which is not preferable because the catalyst efficiency may be lowered.

The dye is the same as described above.

The light absorption layer may further include an additive selected from the group consisting of a compound having a structure of Formula 6 together with the dye to improve the photoelectric efficiency of the solar cell.

[Formula 6]

(In Formula 6, X is a substituted or unsubstituted alkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 3 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, 3 to 20 carbon atoms Substituted or unsubstituted alkylthio group, ether group, thioether group, ester group, substituted or unsubstituted amino group, substituted or unsubstituted aryleneoxy group having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl group, carbon number Substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, substituted or unsubstituted arylene group having 6 to 30 carbon atoms, substituted or unsubstituted alkylene group having 3 to 20 carbon atoms, substituted or unsubstituted alkyl having 3 to 20 carbon atoms A lenoxy group, and combinations thereof.)

More preferably, the additive is dioxycholic acid having a structure of Formula 7 below.

[Formula 7]

The additive may be included in an amount of 100 to 3000 parts by weight, and more preferably 100 to 2000 parts by weight, based on 100 parts by weight of the dye. If the content of the additive is less than 100 parts by weight, dye aggregation occurs, which is not preferable. If the content is more than 3000 parts by weight, the amount of dye adsorption is undesirable.

In such a composition, the light absorbing layer may have a thickness of 25 μm or less, preferably 1 to 25 μm, more preferably 5 to 25 μm. If the thickness of the light absorbing layer exceeds 25 占 퐉, the series resistance becomes large for structural reasons, and as a result, electron transfer efficiency to the transparent electrode is lowered, which may lower the conversion efficiency. Therefore, by setting the film thickness of the light absorbing layer to 25 μm or less, it is possible to keep the series resistance low while maintaining the function thereof, thereby preventing a decrease in conversion efficiency.

Any of the conductive materials can be used as the second electrode (counter electrode, counter electrode) 14 without limitation. If the insulating material is provided on the side facing the first electrode, this can also be used. Do. Specifically, Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C, conductive polymers and combinations thereof may be used.

As the second electrode, indium tin oxide (ITO), fluorine tin oxide (FTO), ZnO- (Ga ₂ O ₃ Or Al ₂ O ₃ ), tin-based oxides, and combinations thereof, in a glass or plastic substrate comprising Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir , Os, C, it is preferable to use those having a conductive layer comprising a material selected from the group consisting of a conductive polymer and combinations thereof.

In addition, it is preferable that the side facing the first electrode has a microstructure that can increase the surface area for the purpose of improving the catalytic effect of redox. For example, in the case of Pt or Au, the black state ('black state' in the present invention means a state not supported on the carrier) is preferably a porous state in the case of carbon. In particular, the platinum black state can be formed by platinum anodization, platinum acid treatment, or the like, and the carbon in the porous state can be formed by sintering carbon fine particles or firing organic polymers.

The electrolyte layer 13 is made of an electrolyte solution. The electrolyte is an iodide / triodide pair and serves to transfer electrons from the counter electrode to the dye by oxidation and reduction, and the open circuit voltage is the energy level of the dye and the electrolyte. It is determined by the difference between the acid and reduction levels.

The electrolyte is uniformly dispersed between the first electrode and the second electrode, and may also be infiltrated into the light absorption layer.

As the electrolyte solution, for example, a solution in which iodine is dissolved in acetonitrile may be used, but the present invention is not limited thereto, and any electrolyte may be used without limitation.

Dye-sensitized solar cell according to an embodiment of the present invention having a structure as described above, the step of manufacturing a first electrode using a conductive transparent substrate; Forming a light absorption layer including semiconductor fine particles and a dye on one surface of the first electrode; Manufacturing a second electrode; And disposing an electrolyte between the first electrode and the second electrode after disposing the first electrode and the second electrode such that the first electrode and the second electrode on which the light absorption layer is formed face each other. Can be prepared.

Since the method for manufacturing a solar cell having the above-described structure is well known in the art and can be sufficiently understood by those skilled in the art, a detailed description thereof will be omitted. However, only the process of forming the light absorption layer, which is a main feature of the present invention, will be described in detail.

First, a conductive transparent substrate is prepared to be a first electrode.

Next, a paste including semiconductor fine particles may be coated on one surface of the conductive transparent substrate and subjected to heat treatment to form a semiconductor fine particle layer in the form of a porous membrane.

In this case, the physical properties of the paste required by the coating method also vary slightly. Generally, the paste may be coated by a method such as a doctor braid or a screen print, or a spin coating or spray method may be used to form a transparent film. In addition, general wet coating methods can be applied. It is preferable to perform heat processing for about 30 minutes at 400-600 degreeC when a binder is added, and it can carry out at the temperature of 200 degrees C or less when a binder is not added.

In addition, for the purpose of maintaining the porosity of the porous membrane, the polymer may be added to the porous membrane and heat treated (400 to 600 ° C.) to further increase the porosity. In this case, it is preferable to use a polymer in which no organic substance remains after the heat treatment. Specifically, ethylene cellulose (EC), hydroxy propyl cellulose (HPC), polyethylene glycol (PEG), polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyridone (PVP), or the like can be used. Among these, in consideration of the coating conditions including the coating method, those having a suitable molecular weight are appropriately selected and used. The addition of such a polymer may improve not only the porosity but also the dispersibility and the viscosity, thereby improving the film formability and adhesion to the substrate.

The dye layer may be formed by adsorbing the dye on the semiconductor fine particles by spraying, applying or dipping the dispersion liquid containing the dye on the prepared semiconductor fine particle layer. The dispersion may further include an additive which may increase photoelectric efficiency of the solar cell together with the dye. The additive is the same as described above. The additive is preferably included in the concentration of 0.3 to 60mM in the dispersion, more preferably at a concentration of 5 to 40mM so that it may be included in 100 to 3000 parts by weight relative to 100 parts by weight of the dye in the photocatalyst layer of the final solar cell prepared. May be included. If the additive content in the dispersion is less than 0.3 mM, dye aggregation occurs, which is not preferable.

The adsorption of the dye is naturally adsorbed after about 12 hours after immersing the first electrode in which the semiconductor fine particle layer is formed in the dispersion containing the dye. The dye is the same as described above. The solvent for dispersing the dye is not particularly limited, but acetonitrile, dichloromethane, an alcohol solvent or the like can be used.

In addition, the dispersion containing the dye may further include an organic pigment of various colors to improve the absorption by improving the visible light of the long wavelength. In this case, as the organic pigment, cumarine, or pheophorbide a, a kind of porphyrin, may be used.

After the dye layer is formed, the light absorbing layer can be prepared by washing the dye that is not adsorbed by a method such as solvent washing.

A second electrode is prepared by forming a conductive layer including a conductive material on a separate conductive transparent substrate by using physical vapor deposition (PVD), such as electroplating, sputtering, or electron beam deposition.

After disposing the first electrode and the second electrode so that the light absorption layer and the second electrode face each other, the electrolyte is buried and sealed between the light absorption layer and the second electrode to provide a dye-sensitized solar cell according to an embodiment of the present invention. Manufacture.

The first electrode and the second electrode may be bonded to each other using an adhesive. As the adhesive, a thermoplastic polymer film may be used, and for example, a trade name surlyn (manufactured by DuPont) may be used. The thermoplastic polymer film is positioned between the two electrodes and then sealed by heat compression. Another kind of adhesive may be an epoxy resin or an ultraviolet (UV) curing agent, in which case it may be cured after heat treatment or UV treatment.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited to the following examples.

Example  1: Fabrication of Dye-Sensitized Solar Cells

A titanium oxide dispersion having a particle size of about 5 to 15 nm was coated on an indium-doped tin oxide transparent conductor in a 1 cm ² area using the doctor blade method, and a porous titanium oxide thick film having a thickness of 18 μm was subjected to a heat treatment and baking process at 450 ° C. for 30 minutes. Was produced. After maintaining the specimen at 80 ° C., the compound having the structure of Formula 2 was immersed in 0.3 mM dye dispersion dissolved in ethanol, and the dye adsorption treatment was performed for 12 hours or more. After the dye-adsorbed porous titanium oxide thick film was washed with ethanol and dried at room temperature to prepare a first electrode having a light absorption layer.

As a second electrode, a Pt layer was deposited to a thickness of about 200 nm using a sputter on an indium doped tin oxide transparent conductor. For injection of the electrolyte, a second hole was manufactured by making a minute hole using a 0.75 mm diameter drill.

The two electrodes were bonded by pressing a 60 μm-thick thermoplastic polymer film between the first electrode and the second electrode for 9 seconds at 100 ° C. A redox electrolyte was injected through the micropores formed in the second electrode, and a dye-sensitized solar cell was manufactured by sealing the micropores using a cover glass and a thermoplastic polymer film. The redox electrolyte used was 0.62M 1,2-dimethyl-3-hexylimidazolium iodide (1,2-dimethyl-3-hexylimidazolium iodide), 0.5M 2-aminopyrimidine (2- aminopyrimidine), 0.1 M LiI and 0.05 M I ₂ dissolved in an acetonitrile solvent were used.

[Formula 2]

Example  2: Fabrication of Dye-Sensitized Solar Cells

A dye-sensitized solar cell was prepared in the same manner as in Example 1, except that the compound having the structure of Formula 3 was used as the dye.

[Formula 3]

Example  3: Fabrication of Dye-Sensitized Solar Cells

In Example 1, a dye-sensitized solar cell was prepared in the same manner as in Example 1, except that dioxycholine acid of Formula 7 was further added to the dye dispersion at a concentration of 5 mM.

[Formula 7]

Example  4: Fabrication of Dye-Sensitized Solar Cells

In Example 1, a dye-sensitized solar cell was prepared in the same manner as in Example 1, except that dioxycholine acid of Chemical Formula 7 was further added to the dye dispersion at 40 mM concentration.

Comparative example  1: Fabrication of Dye-Sensitized Solar Cells

A titanium oxide dispersion having a particle size of 5 to 15 nm was coated on an indium-doped tin oxide transparent conductor in a 1 cm ² area by using a doctor blade method, and a porous titanium oxide thick film having a thickness of 18 μm was subjected to a heat treatment and baking process at 450 ° C. for 30 minutes. Was produced. After maintaining the specimen at 80 ° C., the compound having the structure of Formula 8 was immersed in 0.3 mM dye dispersion dissolved in ethanol, and the dye adsorption treatment was performed for 12 hours or more. After the dye-adsorbed porous titanium oxide thick film was washed with ethanol and dried at room temperature to prepare a first electrode having a light absorption layer.

As a second electrode, a Pt layer was deposited to a thickness of about 200 nm using a sputter on an indium doped tin oxide transparent conductor. For injection of the electrolyte, a second hole was manufactured by making a minute hole using a 0.75 mm diameter drill.

The two electrodes were bonded by pressing a 60 μm-thick thermoplastic polymer film between the first electrode and the second electrode for 9 seconds at 100 ° C. A redox electrolyte was injected through the micropores formed in the second electrode, and a dye-sensitized solar cell was manufactured by sealing the micropores using a cover glass and a thermoplastic polymer film. The redox electrolyte used was 0.62M 1,2-dimethyl-3-hexylimidazolium iodide (1,2-dimethyl-3-hexylimidazolium iodide), 0.5M 2-aminopyrimidine (2- aminopyrimidine), 0.1 M LiI and 0.05 M I ₂ dissolved in an acetonitrile solvent were used.

[Formula 8]

Comparative example  2: Fabrication of Dye-Sensitized Solar Cells

A dye-sensitized solar cell was prepared in the same manner as in Comparative Example 1 except that the compound of Formula 9 was used as the dye.

[Formula 9]

Comparative example  3: Fabrication of Dye-Sensitized Solar Cells

A dye-sensitized solar cell was prepared in the same manner as in Comparative Example 1 except that the compound of Formula 10 was used as the dye.

[Formula 10]

Comparative example  4: Fabrication of Dye-Sensitized Solar Cells

In Comparative Example 3, a dye-sensitized solar cell was manufactured in the same manner as in Comparative Example 3, except that dioxycholine acid of Chemical Formula 7 was further added to the dye dispersion at 40 mM concentration.

The photocurrent voltages of the dye-sensitized solar cells prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were measured, and an open-circuit voltage (Voc) and a short-circuit current were measured from the measured photocurrent curve. : Jsc) and fill factor (FF) were calculated. Moreover, the efficiency of the solar cell was evaluated from this.

At this time, xenon lamp (Oriel, 01193) was used as the light source, and the solar condition (AM 1.5) of the xenon lamp was a standard solar cell (Frunhofer Institute Solare Engeriessysteme, Certificate No. C-ISE369, Type of material: Mono-Si + KG filter). The results are shown in Table 1 and FIG. 2.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Open voltage (V) 0.69 0.66 0.67 0.69 0.53 0.55 0.56 0.57 Current density (mA / cm ² ) 10.71 10.71 11.61 12.16 4.57 7.35 9.07 10.61 F.F 64 66 66 71 53 64 58 65 efficiency(%) 4.72 4.67 5.15 5.96 1.29 2.61 2.91 3.93

As a result, the open-circuit voltages (Voc) in the solar cells of Examples 1 to 4 were all 0.66 V or more, while the open voltages of the solar cells of Comparative Examples 1 to 4 were 0.6 V or less. In addition, the current density and the filling factor were also higher in the dye-sensitized solar cells of Examples 1 to 4 than in the dye-sensitized solar cells of Comparative Examples 1 to 4, and as a result, the dye-sensitized solar cells of Examples 1 to 4 were Comparative Examples 1 to 4. Compared with the dye-sensitized solar cell of 4, it showed a remarkably superior photoelectric efficiency. From this, it was confirmed that the dye of the present invention contained in the dye-sensitized solar cells of Examples 1 to 4 exhibited an excellent effect compared to the dyes used in Comparative Examples 1 to 4.

In addition, when the solar cells of Examples 1 and 2 were compared with those of Examples 3 and 4, the dye-sensitized solar cells of Examples 3 and 4, which contained dioxycholic acid as an additive, contained only dyes. Compared with the dye-sensitized solar cell of 2 and 2, it showed better characteristics in terms of open voltage, current density, filling coefficient and photoelectric efficiency. In addition, this photoelectric effect increased as the concentration of the additive was increased.

FIG. 2 is a graph showing the change in photoelectric yield (IPCE) in unit wavelengths for the dye-sensitized solar cells of Examples 1 and 3. FIG.

As shown in FIG. 2, the solar cell of Example 3 including the fluorenyl group-containing organic dye and the additive of the present invention has a unit wavelength compared to the solar cell of Example 1 containing only the fluorenyl group-containing organic dye alone. The overcharge yield at was higher. That is, it was confirmed that the organic dye into which the fluorenyl functional group of the present invention was introduced was co-adsorbed to TiO ₂ , such as dioxycholine acid, to show an increased amount of current compared to when using the fluorenyl group-containing organic dye alone.

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

Claims (19)

Dye-sensitized solar cell dye comprising a compound having the structure of formula [Formula 1]

(In Formula 1, A and B are each independently selected from the group consisting of a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocycle, and a combination thereof, wherein at least one of A and B is fluorenyl Gigi, D is selected from the group consisting of a vinyl group, a substituted or unsubstituted polyvinyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, and a combination thereof, E is an acidic functional group.) The method of claim 1, A and B are each independently selected from the group consisting of a substituted or unsubstituted aromatic hydrocarbon group having 5 to 20 carbon atoms, a substituted or unsubstituted heterocycle, and a combination thereof, at least one of A and B is fluorine Dye for dye-sensitized solar cells which is a nil group. The method of claim 1, A and B are hydroxy, alkyl, halo, haloalkyl, nitro, cyano, alkoxy, alkylamino, aryl group, alkylthio group, ether group, thioether group, amino group, aryleneoxy group, alkenyl group, aryl jade Dye for a dye-sensitized solar cell comprising a substituent selected from the group consisting of time, arylene group, alkylene group, alkyleneoxy group and combinations thereof. The method of claim 1, The D is a vinyl group, polyvinyl group, benzene, naphthalene, anthracene, pyrene, phenanthrene, indene, perylene, fluorene, biphenyl, terphenyl, pyridine, pyrazine, pyrimidine, pyrazole, pyrazolidine, pyran , Pyrrole, benzoimidazole, imidazoline, imidazolidine, imidazole, pyrazole, triazole, triazine, diazole, morpholine, thiophene, thiazole, benzothiazole, naphthothiazole, benzooxa Dye for solar cells, dye selected from the group consisting of sol, naphthooxazole, pyrazine, quinoline, quinazoline, carbazole and combinations thereof. The method of claim 1, D is hydroxy, alkyl, halo, haloalkyl, nitro, cyano, alkoxy, alkylamino, aryl group, alkylthio group, ether group, thioether group, amino group, aryleneoxy group, alkenyl group, aryloxy group And dyes selected from the group consisting of arylene groups, alkylene groups, alkyleneoxy groups, and combinations thereof. The method of claim 1, E is a dye for a solar-sensitized dye-sensitized solar cell which is a substituent selected from the group consisting of carboxyl groups, phosphorous acid groups, sulfonic acid groups, phosphinic acid groups, hydroxy groups, oxycarboxylic acids, acidamides, boric acid groups, squaric acid groups, and combinations thereof. The method of claim 1, A and B are each independently selected from the group consisting of a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted hetero ring, and a combination thereof, wherein at least one of A and B is fluorenyl ), D is

or

Is, R ₁ to R ₅ are each independently hydroxy, alkyl, halo, haloalkyl, nitro, cyano, alkoxy, alkylamino, aryl group, alkylthio group, ether group, thioether group, amino group, aryleneoxy group, Alkenyl group, aryloxy group, arylene group, alkylene group, alkyleneoxy group and combinations thereof, m, n, p and q are integers of 0 or 4, o and s is 1 Or 2 E is a dye for solar cells of a dye-sensitized solar cell. The method of claim 1, The dye is a dye for a solar cell dye-sensitized solar cell comprising a compound having a structure of the formula 2 to 5 and combinations thereof. [Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

A first electrode comprising a conductive transparent substrate; A light absorbing layer formed on one surface of the first electrode; A second electrode disposed to face the first electrode on which the light absorption layer is formed; And An electrolyte located between the first electrode and the second electrode, The dye-sensitized solar cell of claim 1, wherein the light absorbing layer comprises semiconductor fine particles, and the dye according to any one of claims 1 to 8.  The method of claim 9, The conductive transparent substrate may be a glass substrate or plastic including a material selected from the group consisting of indium tin oxide, fluorine tin oxide, ZnO— (Ga ₂ O ₃ or Al ₂ O ₃ ), tin oxide, and combinations thereof. Dye-sensitized solar cell that is a substrate. The method of claim 9, The plastic substrate is a dye-sensitized solar cell comprising one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polyimide, triacetyl cellulose, and combinations thereof. The method of claim 9, The semiconductor fine particle is a dye-sensitized solar cell is selected from the group consisting of a single semiconductor, a metal oxide, a composite metal oxide having a perovskite structure, and combinations thereof. The method of claim 9, The semiconductor fine particles are selected from the group consisting of Si, TiO ₂ , SnO ₂ , ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ and combinations thereof. The method of claim 9, The dye-sensitized solar cell of which the semiconductor fine particles have an average particle diameter of 50 nm or less. The method of claim 9, The light absorbing layer is a dye-sensitized solar cell further comprises an additive selected from the group consisting of a compound having a structure of formula (6). [Formula 6]

(In Chemical Formula 6, X is a substituted or unsubstituted alkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 3 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, 3 to carbon atoms 20 substituted or unsubstituted alkylthio group, ether group, thioether group, ester group, substituted or unsubstituted amino group, substituted or unsubstituted aryleneoxy group having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl group, Substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, Substituted or unsubstituted arylene group having 6 to 30 carbon atoms, Substituted or unsubstituted alkylene group having 3 to 20 carbon atoms, Substituted or unsubstituted alkyl group having 3 to 20 carbon atoms Alkyleneoxy groups, and combinations thereof.) The method of claim 9, The additive is a dye-sensitized solar cell is deoxycholic acid. The method of claim 9, The additive is a dye-sensitized solar cell that is included in 100 to 3000 parts by weight based on 100 parts by weight of the dye. The method of claim 9, The light absorbing layer is a dye-sensitized solar cell having a thickness of 25㎛ or less. The method of claim 9, The second electrode includes a material selected from the group consisting of Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C, conductive polymers, and combinations thereof. battery.

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