KR101320394B1 - Dyes for dye-sensitive solar cells, manufacturing method thereof and solar cells using the same - Google Patents

Abstract

Dyes for dye-sensitized solar cells, methods for producing the same, and solar cells employing the same are provided.

Description

Dye for dye-sensitized solar cell, manufacturing method thereof and solar cell employing the same {Dyes for dye-sensitive solar cells, manufacturing method according to solar cell using the same}

Dye-sensitized solar cell dye, a manufacturing method thereof, and a solar cell employing the same.

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 infinite 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 the cell 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, are composed mainly of photosensitive dye molecules capable of absorbing visible light to produce electron-hole pairs, and transition metal oxides for transferring the generated electrons. Photoelectrochemical solar cell. A representative example of dye-sensitized solar cells known so far was published by Gratzel et al., Switzerland, in 1991, which can replace conventional solar cells due to lower manufacturing cost per power than conventional silicon solar cells. Has been attracting attention.

The conventional structure of such a dye-sensitized solar cell consists of a conductive transparent substrate, a light absorbing layer, an electrolyte layer, and a counter electrode, and the light absorbing layer includes semiconductor fine particles and a dye. When sunlight is absorbed by the dye molecule, the dye molecule electron-transfers from the ground state to the excited state to form an electron-hole pair, which is injected into the conduction band of the titanium oxide particle interface, and the injected electron It is transferred through the interface to the conductive transparent substrate and travels through the external circuit to the opposite electrode. On the other hand, the dye oxidized as a result of the electron transition is reduced by ions of the redox couple in the electrolyte layer, and the oxidized ions are reduced by reacting with the electrons reaching the interface of the counter electrode to achieve charge neutrality. The dye-sensitized solar cell is operated.

In the dye-sensitized solar cell, the first step of driving the solar cell is a process of generating photocharges from light energy. For this purpose, the dye molecules are excited by absorbing light transmitted through the conductive transparent substrate. Dye molecules are known to use those containing organometallic complexes.

Although such dyes have excellent quantum yields, the efficiency of solar cells is insufficient, and development of dyes having better performance is required.

One aspect is to provide a dye for a dye-sensitized solar cell comprising an organometallic complex having a ratio of bidentate ligand to counter ions different from existing organometallic complexes.

Another aspect is to provide a method for producing the dye for the dye-sensitized solar cell.

Another aspect is to provide a solar cell employing the dye for the dye-sensitized solar cell.

According to one aspect, there is provided a dye for a dye-sensitized solar cell comprising an organometallic complex represented by the following formula (1):

≪ Formula 1 >

Wherein M is a metal element of Groups 8 to 10 on the periodic table, X is an auxiliary ligand selected from the group consisting of -CN, -OH, -I, -Cl, -NCO, -NCS and -NCSe, L Is a bidentate ligand represented by the following formula (2),

<Formula 2>

Z is a counter ion represented by the following formula (3),

<Formula 3>

Wherein R ₁ and R ₂ are independently from each other selected from the group consisting of COOH, PO ₃ H ₂ , PO ₄ H ₂ , SO ₃ H ₂ , SO ₄ H ₂ and CONHOH and any one of R ₁ and R ₂ is de and the quantized state, R ₃ to R ₆ independently represent a substituted or unsubstituted C _{1 - 20} alkyl group, a substituted or unsubstituted C _{1 - 20} alkoxy group, a substituted or unsubstituted C _{2 - 20} alkenyl group, a substituted or unsubstituted C _{2 - 20} alkynyl group, a substituted or unsubstituted C _{6 - 30} aryl group, a substituted or unsubstituted C _{6 - 30} aryloxy group and a substituted or unsubstituted C _{2 - 30} hetero group, aryl And a molar ratio (p / q) of L to Z is from 1.1 to 1.4.

In Formula 1, M may be Ru (ruthenium).

In Formula 1, X may be -NCS.

In Formula 1, L may be represented by Formula 4 below:

&Lt; Formula 4 >

.

.

In Formula 1, Z may be represented by the following Formula 5:

&Lt; Formula 5 >

The dye-sensitized solar cell dye may include 70 to 99% by weight of the organometallic complex represented by Formula 6 below:

(6)

.

.

According to another aspect, preparing an organometallic complex represented by Formula 7 below, 100 parts by weight of the organometallic complex, 80 to 150 parts by weight of tetrabutylammonium thiocyanate and 20 to 80 parts by weight of tetrabutylammonium hydroxide A method of preparing the dye for a dye-sensitized solar cell is provided comprising mixing a portion to prepare a solution and purifying the solution at pH 3.8 to 4.1:

&Lt; Formula 7 >

In the above formula, M, X, L and Z are as described above.

According to another aspect, 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 positioned between the first electrode and the second electrode, wherein the light absorption layer includes semiconductor fine particles and dye for the dye-sensitized solar cell. Dye-sensitized solar cells are provided.

The solar cell including the dye for the dye-sensitized solar cell according to one embodiment has a high conversion efficiency.

1 is a schematic diagram showing the operating principle of a dye-sensitized solar cell.
2 illustrates a structure of a dye-sensitized solar cell according to one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, a dye for a dye-sensitized solar cell according to one or more exemplary embodiments, a manufacturing method thereof, and a solar cell employing the same will be described in more detail with reference to the accompanying drawings.

Dye for a dye-sensitized solar cell according to one embodiment includes an organometallic complex represented by the following formula (1):

&Lt; Formula 1 >

Wherein M is a metal element of Groups 8 to 10 on the periodic table, X is an auxiliary ligand selected from the group consisting of -CN, -OH, -I, -Cl, -NCO, -NCS and -NCSe, L Is a bidentate ligand represented by Formula 2, Z is a counter ion represented by Formula 3, and the molar ratio (p / q) of L to Z is 1.1 to 1.4:

<Formula 2>

<Formula 3>

In Formula 2, R ₁ and R ₂ are independently selected from COOH, PO ₃ H ₂ , PO ₄ H ₂ , SO ₃ H ₂ , SO ₄ H ₂ and CONHOH, and any one of R ₁ and R ₂ is deprotonated state and, in the general formula 3 R ₃ to R ₆ independently represent a substituted or unsubstituted C ₁ to each other _{- 20} alkyl group, a substituted or unsubstituted C _{1 - 20} alkoxy group, a substituted or unsubstituted C _{2 - 20} alkenyl group, a substituted or unsubstituted C _{2 - 20} alkynyl group, a substituted or unsubstituted C _{6 - 30} aryl group, a substituted or unsubstituted C _{6 - 30} aryloxy group and a substituted or unsubstituted C _{2 - 30} heteroaryl group.

1 illustrates the operation principle of a dye-sensitized solar cell. When sunlight is absorbed by the dye molecule 5, the dye molecule 5 electron-transfers from the ground state to the excited state to form an electron-hole pair, and the electron in the excited state. Is injected into the conduction band of the porous membrane 3 particle interface, and the injected electrons are transferred to the first electrode 1 through the interface of the first electrode 1 and moved to the second electrode 2 through an external circuit. do. On the other hand, the dye oxidized as a result of the electron transfer is reduced by the iodine ion (I ^- ) of the redox couple in the electrolyte (4), and the oxidized trivalent iodine ion (I ₃ ^- neutrality, the battery is operated by a reduction reaction with electrons reaching the interface of the second electrode 2. Thus, the dye-sensitized solar cell has an electrochemical principle that operates by interfacial reaction unlike the conventional pn junction type silicon-based solar cell.

The organometallic complex of Formula 1 has the basic form of Gratzel's dye used in dye-sensitized solar cells and has two bidentate ligands (L) and two auxiliary ligands (X). The molar ratio of the bidentate ligand and the counter ion in the compound is controlled within a certain range.

In Formula 1, M may be selected from the group consisting of Ru (ruthenium), Os (osmium), Fe, and Rh (renium) as metal elements of Groups 8 to 10 on the periodic table. For example, M can be Ru.

In Formula 1, L is a bidentate ligand having a coordination bond with M, and may be represented by Formula 2 below:

<Formula 2>

Here, R ₁ and R ₂ may be independently selected from COOH, PO ₃ H ₂ , PO ₄ H ₂ , SO ₃ H ₂ , SO ₄ H ₂ and CONHOH, any one of R ₁ and R ₂ One is dequantized.

In the organometallic complex represented by Chemical Formula 1, a metal element of Groups 8 to 10 is located at the center thereof, and two bidentate ligands (L) represented by Chemical Formula 2 are bonded to the metal element, and another auxiliary ligand (X) is The structure of the organometallic complex having such a structure is a two-bonded structure, because the bidentate ligand (L) represented by the formula (2) forms a basic skeleton, and the characteristic of the organometallic complex is the bidentate ligand represented by the formula (2). It is most affected by the structure of (L).

Since L has an -N group, a non-covalent electron pair of nitrogen atoms can bond strongly with the metal M, and the organometallic complex forming such a strong coordination bond has excellent adsorption force on the surface of semiconductor fine particles in the light absorption layer. Therefore, when the organometallic complex is used as a dye of the solar cell, electrons generated in the dye molecule can easily move to the semiconductor fine particles, and consequently, the light conversion efficiency of the solar cell can be improved. That is, the organometallic complex having a structure in which the bidentate ligand (L) is represented by the formula (2) has enhanced adsorption capacity at the contact interface with the semiconductor fine particles, so that the movement of electrons becomes easier as the interface resistance decreases. Smooth movement leads to an increase in the light conversion efficiency as a whole.

Since the end groups R ₁ and R ₂ of the bidentate ligand (L) have a great influence on the properties of the bidentate ligand (L) itself, the end groups R ₁ and R ₂ are an organic metal represented by Formula 1 It will greatly affect the adsorption capacity of the complex. R ₁ and R ₂ may be an acid having excellent reactivity, and specifically, may be selected from the group consisting of COOH, PO ₃ H ₂ , PO ₄ H ₂ , SO ₃ H ₂ , SO ₄ H _2, and CONHOH.

For example, the bidentate ligand (L) may be represented by the following Chemical Formula 4 having a bipyridine derivative skeleton including nitrogen having a non-covalent electron pair and having a -COOH end group. Provided that one of the -COOH corresponding to the end group is deprotonated due to the release of hydrogen:

&Lt; Formula 4 >

The bidentate ligand (L) having the structure of Formula 4 includes a non-covalent electron pair and a functional group such as -COOH in the structure, thereby improving affinity with semiconductor fine particles present in the light absorption layer, and as a result, a contact interface. It is possible to enable the smooth movement of electrons in the.

In Formula 1, Z is a counter ion of the bidentate ligand (L), and may be represented by the following Formula 3:

<Formula 3>

Here, R ₃ to R ₆ independently represent a substituted or unsubstituted C _{1 - 20} alkyl group, a substituted or unsubstituted C _{1 - 20} alkoxy group, a substituted or unsubstituted C _{2 - 20} alkenyl group, a substituted or unsubstituted a C _{2 -} to be selected from the ₃₀ heteroaryl group consisting of a _{- 20} alkynyl group, a substituted or unsubstituted C _{6 - 30} aryl group, a substituted or unsubstituted C _{6 -30} aryloxy group and a substituted or unsubstituted C ₂ Can be.

* Z is a counter ion corresponding to the end group of the bidentate ligand (L) (the hydrogen in R ₁ and R ₂ is deprotonated). The counter ion (Z) is in the form of a monovalent cation with N atoms in the center and four functional groups at the binding site of N atoms. The functional group bonded to the N atom which is located at the center of the counter ions (Z) is a substituted or unsubstituted C _{1 - 20} alkyl group, a substituted or unsubstituted C _{1 - 20} alkoxy group, a substituted or unsubstituted C _{2 - 20} alkenyl group, a substituted or unsubstituted C _{2 - 20} alkynyl group, a substituted or unsubstituted C _{6 - 30} aryl group, a substituted or unsubstituted C _{6 - 30} aryloxy group and a substituted or unsubstituted C _{2 - 30} heteroaryl It may be selected from the group consisting of groups.

For example, Z may be tetrabutylammonium (TBA ⁺ ) having four n-butyl groups bonded to a centrally located N atom, and may be represented by the following Chemical Formula 5:

&Lt; Formula 5 >

In Formula 1, X is an auxiliary ligand for satisfying the charge neutrality of the organometallic complex, and may be -CN, -OH, -I, -Cl, -NCO, -NCS, and -NCSe in terms of electrochemical properties. For example, X can be -NCS.

In Formula 1, the molar ratio of L to Z is 1.1 to 1.4.

The molar ratio of L to Z is a molar ratio of the bidentate ligand represented by Formula 2 to the relative ion represented by Formula 3, and ideally, one bidentate ligand will be paired with one relative ion. Can be. The bidentate ligand has a monovalent negative charge due to the release of hydrogen from one end group, and the counter ion is a monovalent cation because the nitrogen in the center does not have a non-covalent electron pair. Thus the ideal molar ratio of L to Z may be one. In practice, however, it is thought that higher conversion efficiency can be obtained when the molar ratio of L to Z is 1 or more due to the improvement of dye adsorption properties. That is, L contains an anchoring group (-COO-H ⁺ ) that determines the adsorption characteristic of the dye on the porous titanium oxide surface. As the p / q ratio increases, the amount of dye adsorbed to the electrode increases. I think.

On the other hand, when the molar ratio of L to Z is an ideal value of 1 or greater than 1, the organometallic complex may form isomers unnecessary for adsorption and the formed isomers may degrade the conversion efficiency characteristics of the dye in the solar cell. Therefore, when the molar ratio of L to Z satisfies 1 to 1.4, the organometallic complex does not form unnecessary isomers for adsorption, so that the dye-sensitized solar cell using the dye containing the same increases current and photoelectric conversion efficiency.

For example, the dye-sensitized solar cell dye is an organic metal complex represented by the following formula (6) wherein X is -NCS, L is represented by the formula (4), Z is represented by the formula (5) and the ratio of L to Z is 1. It may include 70 to 99% by weight relative to the total weight:

(6)

Such dye-sensitized solar cell dyes are either organic metal complexes having a L: Z ratio of 1: 1 (eg, an organic metal complex having a L: Z ratio of 2: 1) or isomers having an auxiliary ligand X of -S = C = N. It includes some.

The molar ratio of L to Z can be controlled by purifying by adjusting the pH to 3.8 to 4.1 in the preparation step of the organometallic complex represented by Chemical Formula 1.

The dye-sensitized solar cell dye production method is to prepare an organometallic complex represented by the following formula (7), 100 parts by weight of the organic metal complex, 80 to 150 parts by weight of tetrabutylammonium thiocyanate and tetrabutylammonium hydroxide 20 To 80 parts by weight of a mixture prepared to form a solution, followed by purification of the solution at pH 3.8 to 4.1:

&Lt; Formula 7 >

In Formula 7, M, X, L, and Z are as described above.

For example, the manufacturing method of the said dye-sensitized solar cell dye is as follows.

Dichloro (p-cymene) ruthenium (II) dimmer (0.2 mmol, 1 equiv) and 4,4′-bis (carboxylic acid) -2,2′- A mixture of bipyridine (4,4´-bis (carboxylic acid) -2,2´-bipyridine) (0.8 mmol, 4 equiv) was stirred and distilled at 160 ° C. for 4 hours in a solvent of dimethylformamide (DMF). Let's do it. NH ₄ NCS (4 mmol, 10 equivalents) was added thereto, followed by further distillation at 130 ° C. for 5 hours. The solvent is evaporated under vacuum, excess water is added and filtered into a reduced pressure flask. Take a purple solid that is insoluble in water and wash with water and diethyl ether. An aqueous solution of tetra-butyl ammonium hydroxide (2 equivalents) was added to dissolve the solid, and the solid was dissolved in a Sephadex LH-20 column, and water was separated as a developer. The separated solution is adjusted to pH 3.8 to 4.1 using 0.01 M nitric acid solution and recrystallized at 4 ° C. for 12 hours.

Here, the molar ratio of the bidentate ligand to the counter ion can change according to the change of pH of the purification step, and when the pH is 3.8 to 4.1, the molar ratio becomes larger than the theoretical value of 1. Isomers may form when the pH is outside the range of 3.8 to 4.1, and solar cells employing dyes containing the same may have poor conversion efficiency as described above. Formulas 8 and 9 are examples of such isomers:

   <Formula 8> <Formula 9>

The dye for the dye-sensitized solar cell prepared by the above method may include 70 to 99% by weight of the organometallic complex represented by Formula 6 below:

(6)

Where M is Ru, X is NCS, L (bidentate ligand) is 2,2'-bipyridyl-4,4'-dicarboxylic acid, and Z (relative ion) is tetra Butylammonium.

The unsubstituted C ₁ used in the present specification _{- 20} alkyl group may be linear and branched, Non-limiting examples include methyl, ethyl, propyl, isobutyl, sec- butyl, pentyl, iso- amyl, hexyl, heptyl, Octyl, nonanyl, dodecyl, and the like. The C _{1 - 20} alkyl group one or more hydrogen atoms are deuterium atom, a halogen atom, a cyano group, an amino group, an amidino group, a nitro group, a hydroxy group, a hydrazine possess group, Hydra Zonyl group, a carboxy group or a salt of a sulfonic acid group or a salt thereof, phosphoric acid or a salt thereof, or a C _{1 - 10} alkyl group, C _{1 - 10} alkoxy groups, C _{2 - 10} alkenyl, C _{2 - 10} alkynyl, C _{6 - 10} aryl, or C _{4 - 10} heteroaryl groups can be substituted Do.

Unsubstituted C _{1 - 20} alkoxy groups -OA (where, A is unsubstituted C ₁ as described above _- 20 alkyl group) means a group having the following structure, and Non-limiting examples include methoxy, ethoxy , Propoxy, isopropyloxy, butoxy, pentoxy, and the like. These alkoxy groups at least one of the hydrogen atoms in the above-described C _{1 -} may be substituted with the substituent of group _20.

Unsubstituted C _{2 - 20} alkenyl group wherein the unsubstituted C _{2 -} means that it contains at least one carbon-carbon double bond in the middle or top end of the ₂₀ group. Non-limiting examples thereof are ethenyl, propenyl, butenyl and the like. The unsubstituted C _{2 - 20} alkenyl group one or more hydrogen atoms in the above-described substituted C _{1 -} may be substituted with the same substituents as in the case of the ₂₀ group.

The unsubstituted C _{2 -} C _{2 20} alkynyl group as defined above, _- means that it contains at least one carbon triple bond in the middle or top end of the ₂₀ group. Non-limiting examples thereof include acetylene, propylene, phenylacetylene, naphthylacetylene, isopropylacetylene, t-butylacetylene, diphenylacetylene and the like. The alkynyl group one or more hydrogen atoms in the above-described substituted C _{1 -} may be substituted with the same substituents as in the case of the ₂₀ group.

Unsubstituted C _{6 - 30} aryl group, if sense and have two or more rings, a carbocycle aromatic system including at least one ring, or fused together, may be connected through a single bond. The term aryl includes aromatic systems such as phenyl, naphthyl, anthracenyl. In addition, one or more hydrogen atoms of said aryl group are the above-mentioned C _{1 -} may be substituted with the same substituents as the substituents in the ₂₀ group. Substituted or unsubstituted C ₆ ring _- An example of a ₃₀ aryl group include phenyl group, C _{1 - 10} alkyl group (for example, ethylphenyl group), a halophenyl group (e.g., phenyl group in o-, m- and p- fluoro, dichlorophenyl group), a cyano group, a dicyanomethylene group, a trifluoromethoxy group, a biphenyl group, a halo-biphenyl group, a cyano group Novi, C _{1 - 10} alkyl biphenyl group, C _{1 - 10} alkoxy biphenyl, o-, m- And p-tolyl group, o-, m- and p-cumenyl group, mesityl group, phenoxyphenyl group, (α, α-dimethylbenzene) phenyl group, (N, N'-dimethyl) aminophenyl group, (N, N˝ -diphenyl) aminophenyl group, penta LES group, indenyl group, a naphthyl group, a naphthyl group, a halo (e.g., fluoro-naphthyl group), C _{1 -10} alkyl, naphthyl (e.g., a methyl naphthyl group), C _{1 -10} alkoxy naphthyl group (e.g., methoxy-naphthyl groups), cyano naphthyl groups, anthracenyl groups, Az LES group, a heptyl group tare, acetoxy tilre naphthyl group, a phenacyl group LES, fluorenyl , Anthraquinolyl group, methyl anthryl group, phenanthryl group, triphenylene group, pyrenyl group, chrysenyl group, ethyl-crisenyl group, pisenyl group, perrylenyl group, chloroperylenyl group, pentaphenyl group, pentaxenyl group And tetraphenylenyl group, hexaphenyl group, hexasenyl group, rubisenyl group, coroneyl group, trinaphthylenyl group, heptaphenyl group, heptasenyl group, pyrantrenyl group and obarenyl group.

Unsubstituted C _{6 - 30} aryloxy group when A1 is a group represented by -OA1 is the C _{6 - 30} aryl group means. Examples of the aryloxy group include a phenoxy group and the like. The aryloxy of one or more hydrogen atoms in the group is the above-mentioned C _{1 -} may be substituted with the same substituents as the substituents in the ₂₀ group.

Unsubstituted C _{2 - 30} heteroaryl group if comprise one, two or three heteroatoms selected from N, O, P or S, and have two or more rings, these are fused with each other may be connected through a single bond . The unsubstituted C _{2 -} An example of a _{30-heteroaryl} groups include, pyrazole group, imidazole group, oxazole group, thiazole group, a triazole group, a tetrazole group, an oxadiazole group, a pyridinyl group, pyridazinyl A group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, an indolyl group, a quinolinyl group, an isoquinolinyl group, etc. are mentioned. In addition, the heteroaryl group, one or more hydrogen atoms of which may be substituted by the same substituents as the substituents of the above-mentioned C _{1 -20} alkyl.

According to one embodiment, the 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 positioned between the first electrode and the second electrode, wherein the light absorption layer is a semiconductor fine particle and an organic metal complex represented by Chemical Formula 1; There is provided a dye-sensitized solar cell comprising a dye for a dye-sensitized solar cell comprising a.

The organometallic complex represented by Chemical Formula 1 is usefully used as a dye molecule in a dye-sensitized solar cell. The dye-sensitized solar cell includes a first electrode, a light absorbing layer, a second electrode, and an electrolyte, and the light absorbing layer may include semiconductor fine particles and dye molecules, wherein the organometallic complex represented by Chemical Formula 1 is formed of the light absorbing layer. It can be used as a dye molecule as a component.

An example of the dye-sensitized solar cell is shown in FIG. 2. The solar cell includes a first electrode 11, a light absorbing layer 12, an electrolyte 13 and a second electrode 14, and the light absorbing layer 12 may include semiconductor fine particles and dye molecules . As described above, the organometallic complex represented by Chemical Formula 1 may be used as a dye molecule that is one component of the light absorption layer 12. On the other hand, the first electrode 11 and the light absorbing layer 12 are collectively referred to as a semiconductor electrode.

A transparent substrate is used for the first electrode 11, and the transparent substrate is not particularly limited as long as it has transparency. For example, a glass substrate or the like can be used. Any material may be used as long as it has conductivity and transparency as a material for imparting conductivity to the transparent substrate. For example, tin-based oxide (eg, SnO ₂ ) having conductivity, transparency, and particularly high heat resistance may be used. And inexpensive indium tin oxide (ITO) may be used.

The light absorption layer 12 includes semiconductor fine particles and a dye, and the thickness thereof may be 15 μm or less, for example, 1 to 15 μm. The light absorbing layer 12 has a large series resistance for structural reasons, and an increase in series resistance leads to a decrease in conversion efficiency. A film thickness of 15 μm or less maintains the function while maintaining the function, thereby decreasing the conversion efficiency. Can be prevented.

As the semiconductor fine particles included in the light absorption layer, a compound semiconductor or a compound having a perovskite structure may be used in addition to the single semiconductor represented by silicon. These semiconductors may be n-type semiconductors in which conduction band electrons become carriers under photo excitation to provide cathode currents. Specifically, there are TiO ₂ (titanium dioxide), SnO ₂ , ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ , and the like, for example, anatase type TiO ₂ . The kind of semiconductor is not limited to these, These can be used individually or in mixture of 2 or more types. The semiconductor particulates may have a large surface area in order to allow the dye adsorbed on the surface to absorb more light. For this purpose, the particle diameter of the semiconductor fine particles may be 20 nm or less.

The dye included in the light absorption layer includes an organometallic complex represented by Chemical Formula 1. Detailed description thereof will be referred to herein.

The manufacturing method of the light absorption layer 12 is as follows. After spraying, applying, or immersing a solution in which the organometallic complex represented by Chemical Formula 1 is dispersed in a solvent on the surface of the semiconductor fine particles, the light absorbing layer 12 is manufactured by washing and drying. The light absorption layer may be prepared after forming the semiconductor fine particles on the first electrode 11 in advance. The solvent for dispersing the organometallic complex is not particularly limited, but acetonitrile, dichloromethane, an alcohol solvent and the like can be used.

In the manufacturing method, after forming the organic metal complex represented by the formula (1) on the surface of the semiconductor fine particles it may be washed by a method such as solvent washing to be a single layer.

The electrolyte 13 may be formed of an electrolyte, and may include the light absorbing layer 12 or may be formed so that the electrolyte is infiltrated into the light absorbing layer 12. The electrolyte may be, for example, an acetonitrile solution of iodine, but is not limited thereto. Any electrolyte may be used without limitation as long as it has a hole conduction function.

The second electrode 14 may be any conductive material and may be used without restriction. Even if the second electrode 14 is an insulating material, the second electrode 14 may be used if the conductive layer is provided on the side facing the semiconductor electrode. However, an electrochemically stable material can be used as the electrode, and specific examples thereof include platinum, gold, and carbon. In addition, for the purpose of improving the catalytic effect of redox, the surface facing the semiconductor electrode may have a microstructure increasing in surface area. For example, if platinum is used, platinum may be in a black state and carbon may be in a porous state. The platinum black state can be formed by anodic oxidation of platinum, chloroplatinic acid treatment or the like, and the porous carbon can be formed by a method such as sintering of carbon fine particles or firing of an organic polymer.

Hereinafter, the present invention will be described in more detail with reference to examples. It is to be understood, however, that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

Example  One

Ru ( dcbpyH ) ₂ (NCS) ₂ ( TBA ) ₂ Purification of

(Where dcbpyH is 2,2′-bipyridyl-4,4′-dicarboxylic acid and TBA is tetrabutylammonium)

0.50 g of Ru (dcbpyH) ₂ (NCS) ₂ (TBA) ₂ , 0.58 g of tetrabutylammonium thiocyanate and 0.27 g of tetrabutylammoniumhydroxide in 100 ml of tertiary distilled water Completely dissolved. The solution was placed in a column packed with Sepadex LH-20 and poured with distilled water. The thick band was separated and the separated solution was adjusted to pH 3.8 using aqueous nitric acid solution. The solution, titrated to pH 3.8, was frozen at −7 ° C. for one day and then thawed, filtered using filter paper and vacuum dried.

The molar ratio of dcbpyH and TBA and the organometallic complex represented by Chemical Formula 6 were determined using 1H-NMR.

Fabrication of Dye-Sensitized Solar Cells

A titanium oxide particle dispersion having a particle size of 15 to 20 nm was coated on a fluorine-doped tin oxide transparent conductor in a 0.18 cm 2 area using a doctor blade method, and the porous titanium having a thickness of 15 μm was subjected to a heat treatment baking process at 500 ° C. for 30 minutes. An oxide thick film was produced. The porous titanium oxide thick film was adsorbed on 0.2 mM of the dye solution dissolved in ethanol for 18 hours or more. After that, the dye-adsorbed porous titanium oxide thick film was washed with ethanol and dried to prepare a semiconductor electrode.

As the counter electrode, a Pt layer was deposited using a sputter on a fluorine doped tin oxide transparent conductor. The counter electrode included micropores made using a 0.6 mm diameter drill for electrolyte injection.

The two electrodes were bonded together by pressing a 60 μm-thick thermoplastic polymer film between the semiconductor electrode and the counter electrode for 10 seconds at 90 ° C. A dye-sensitized solar cell was produced by injecting a redox electrolyte through a fine hole formed in the counter electrode and sealing the fine hole using a cover glass and a thermoplastic polymer film. In this case, the redox electrolyte is 0.62 M of 1-butyl-3-methylimidazolium iodide, 0.1 M of LiI, 0.5 M of I ₂ , and 0.5 M of 4-tert-butyl. Pyridine (4- tert- butylpyridine) dissolved in acetonitrile was used.

A 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 Engeries systeme, Certificate No. C-ISE369, Type of material: Mono-). Si + KG filter). The voltage V _oc calculated from the measured photocurrent voltage curve was 0.751 V, the current density J _sc was 18.745 mA / cm 2, the fill factor FF was 68.2, and the light calculated by the following equation was calculated. Conversion efficiency (Eff) was 9.60%.

The light conversion efficiency calculation equation is as follows.

Eff = (V _oc J _sc FF) / (P _inc )

In the formula, P _inc represents 100 mW / cm 2 (1 sun).

Example  2

Ru ( dcbpyH ) ₂ (NCS) ₂ ( TBA ) ₂ Purification of

0.50 g of Ru (dcbpyH) ₂ (NCS) ₂ (TBA) ₂ , 0.58 g of tetrabutylammonium thiocyanate and 0.27 g of tetrabutylammonium hydroxide were completely dissolved in 100 ml of tertiary distilled water. The solution was placed in a column filled with Sepadex LH-20 and poured with distilled water. The thick band was separated in the middle, and the separated solution was adjusted to pH 4.0 using an aqueous solution of nitric acid. The solution, titrated to pH 4.0, was frozen at -7 ° C for one day, thawed, filtered using filter paper, and dried in vacuo.

The molar ratio of dcbpyH and TBA and the organometallic complex represented by Chemical Formula 6 were determined using 1H-NMR.

Fabrication of Dye-Sensitized Solar Cells

A dye-sensitized solar cell was prepared in the same manner as in Example 1, except that the solution purified at pH 4.0 was used.

The voltage V _oc calculated from the measured photocurrent voltage curve was 0.738 V, the current density J _sc was 19.547 mA / cm 2, the fill factor FF was 69.0, and the light calculated by the following equation was calculated. Conversion efficiency (Eff) was 9.95%.

Comparative Example  One

Ru ( dcbpyH ) ₂ (NCS) ₂ ( TBA ) ₂ Purification of

0.5 g of Ru (dcbpyH) ₂ (NCS) ₂ (TBA) ₂ , 0.58 g of tetrabutylammonium thiocyanate and 0.27 g of tetrabutylammonium hydroxide were completely dissolved in 100 ml of tertiary distilled water. The solution was placed in a column packed with Sepadex LH-20 and poured with distilled water. The thick band was separated in the middle, and the separated solution was adjusted to pH 3.4 using a nitric acid solution. The solution, titrated to pH 3.4, was frozen at −7 ° C. for one day and then thawed, filtered using filter paper and dried in vacuo.

The molar ratio of dcbpyH and TBA and the organometallic complex represented by Chemical Formula 6 were determined using 1H-NMR.

Manufacture of dye-sensitized solar cell

A dye-sensitized solar cell was prepared in the same manner as in Example 1, except that the solution purified at pH 3.4 was used.

The voltage V _oc calculated from the measured photocurrent voltage curve was 0.733 V, the current density J _sc was 18.809 mA / cm 2, the fill factor FF was 68.3, and the light calculated by the following equation was calculated. Conversion efficiency (Eff) was 9.42%.

Comparative Example  2

Ru ( dcbpyH ) ₂ (NCS) ₂ ( TBA ) ₂ Purification of

0.5 g of Ru (dcbpyH) ₂ (NCS) ₂ (TBA) ₂ , 0.58 g of tetrabutylammonium thiocyanate and 0.27 g of tetrabutylammonium hydroxide were completely dissolved in 100 ml of tertiary distilled water. The solution was placed in a column filled with Sepadex LH-20 and poured with distilled water. The thick band was separated in the middle, and the separated solution was adjusted to pH 3.6 using aqueous nitric acid solution. The solution, titrated to pH 3.6, was frozen at −7 ° C. for one day and then thawed, filtered using filter paper and dried in vacuo.

The molar ratio of dcbpyH and TBA and the organometallic complex represented by Chemical Formula 6 were determined using 1H-NMR.

Manufacture of dye-sensitized solar cell

A dye-sensitized solar cell was prepared in the same manner as in Example 1, except that the solution purified at pH 3.6 was used.

The voltage V _oc calculated from the measured photocurrent voltage curve was 0.730 V, the current density J _sc was 16.043 mA / cm 2, the fill factor FF was 68.7, and the light calculated by the following equation was calculated. Conversion efficiency (Eff) was 8.05%.

Comparative Example  3

Ru ( dcbpyH ) ₂ (NCS) ₂ ( TBA ) ₂ Purification of

0.5 g of Ru (dcbpyH) ₂ (NCS) ₂ (TBA) ₂ , 0.58 g of tetrabutylammonium thiocyanate and 0.27 g of tetrabutylammonium hydroxide were completely dissolved in 100 ml of tertiary distilled water. The solution was placed in a column packed with Sepadex LH-20 and poured with distilled water. The thick band was separated in the middle, and the separated solution was adjusted to pH 4.2 using a nitric acid solution. The solution, titrated to pH 4.2, was frozen at −7 ° C. for 1 day and then thawed, filtered using filter paper and vacuum dried.

The molar ratio of dcbpyH and TBA and the organometallic complex represented by Chemical Formula 6 were determined using 1H-NMR.

Manufacture of dye-sensitized solar cell

A dye-sensitized solar cell was prepared in the same manner as in Example 1, except that the solution purified at pH 4.2 was used.

The calculated voltage (V _oc ) was 0.723 V, the current density (J _sc ) was 18.887 mA / cm 2, and the fill factor (FF) was 68.8%, calculated from the following equation. The light conversion efficiency (Eff) was 9.39%.

Comparative Example  4

Ru ( dcbpyH ) ₂ (NCS) ₂ ( TBA ) ₂ Purification of

0.5 g of Ru (dcbpyH) ₂ (NCS) ₂ (TBA) ₂ , 0.58 g of tetrabutylammonium thiocyanate and 0.27 g of tetrabutylammonium hydroxide were completely dissolved in 100 ml of tertiary distilled water. The solution was placed in a column packed with Sepadex LH-20 and poured with distilled water. The thick band was separated in the middle, and the separated solution was adjusted to pH 4.4 using an aqueous solution of nitric acid. The solution, titrated to pH 4.4, was frozen at −7 ° C. for one day and then thawed, filtered using filter paper and vacuum dried.

The molar ratio of dcbpyH and TBA and the organometallic complex represented by Chemical Formula 6 were determined using 1H-NMR.

Manufacture of dye-sensitized solar cell

A dye-sensitized solar cell was prepared in the same manner as in Example 1, except that the solution purified at pH 4.4 was used.

The calculated voltage (V _oc ) was 0.714 V, the current density (J _sc ) was 18.324 mA / cm 2, the fill factor (FF) was 68.5%, and the calculated value was calculated by the following equation. The light conversion efficiency (Eff) was 8.96%.

The pH values and the molar ratios of dcbpyH and TBA in the purification of the dyes obtained according to Examples 1-2 and Comparative Examples 1-4 are shown in Table 1 below. Here, NMR data for the dcbpyH / TBA molar ratio calculation is shown in Figures 3a to 3f.

PH value during purification dcbpyH / TBA molar ratio Example 1 3.8 1.38 Example 2 4.0 1.24 Comparative Example 1 3.4 1.33 Comparative Example 2 3.6 1.33 Comparative Example 3 4.2 1.02 Comparative Example 4 4.4 0.97

The voltage (V _oc ), current density (J _sc ), fill factor (FF) and light conversion efficiency (Eff) of the dye-sensitized solar cells obtained by Examples 1-2 and Comparative Examples 1-4 are shown in the following table. 2 is shown.

Voltage (V _oc ) Current density (JI _sc ) Fill factor (FF) Light conversion efficiency (Eff) Example 1 0.751 18.745 68.2 9.60 Example 2 0.738 19.547 69.0 9.95 Comparative Example 1 0.733 18.809 68.3 9.42 Comparative Example 2 0.730 16.043 68.7 8.05 Comparative Example 3 0.723 18.887 68.8 9.39 Comparative Example 4 0.714 18.324 68.5 8.96

Referring to Table 2, the dye-sensitized solar cell of Example 1-2 has a higher voltage (V _oc ) and a current density (J _sc ), and the filling factor (FF) of the dye-sensitized solar cell of Comparative Example 1-4. It is similar and it can be seen that the light conversion efficiency (Eff) is high.

Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments. It will also be understood that, although not described, equivalent means are also incorporated into the present invention. Therefore, the true scope of protection of the present invention should be defined by the following claims.

1: first electrode, 2: second electrode, 3: porous membrane, 4: electrolyte, 5: dye molecule, 11: first electrode, 12: light absorption layer, 13: electrolyte, 14: second electrode

Claims (10)

Dye-sensitized solar cell dyes comprising an organometallic complex represented by Formula 1 below:
&Lt; Formula 1 >

Wherein,
M is a metal element of Groups 8 to 10 on the periodic table,
X is a co-ligand selected from the group consisting of -CN, -OH, -I, -Cl, -NCO, -NCS and -NCSe,
L is a bidentate ligand represented by the following Chemical Formula 2,
(2)

Z is a counter-ion represented by the following formula (3),
(3)

Wherein R ₁ and R ₂ are independently from each other selected from the group consisting of COOH, PO ₃ H ₂ , PO ₄ H ₂ , SO ₃ H ₂ , SO ₄ H ₂ and CONHOH and any one of R ₁ and R ₂ is de Protonated, R ₃ to R ₆ independently of one another are C _1-20 alkyl, C _1-20 alkoxy, C _2-20 alkenyl, C _2-20 alkynyl, C _6-30 aryl, C _{6 -30} aryloxy group and C _2-30 heteroaryl group,
Each C _1-20 alkyl group, C _1-20 alkoxy group, C _2-20 alkenyl group, C _2-20 alkynyl group, C _6-30 aryl group, C _6-30 aryloxy group and C _2-30 hetero The aryl group is unsubstituted or one or more hydrogen atoms are deuterium atoms, halogen atoms, cyano groups, amino groups, amidino groups, nitro groups, hydroxy groups, hydrazinyl groups, hydrazonyl groups, carboxyl groups or salts thereof, sulfonic acid groups or salts thereof, phosphoric acid Or a salt thereof, or a C _1-10 alkyl group, a C _1-10 alkoxy group, a C _2-10 alkenyl group, a C _2-10 alkynyl group, a C _6-10 aryl group, or a C _4-10 heteroaryl group ,
The molar ratio (p / q) of L to Z is 1.1 to 1.4. The method of claim 1,
In the formula 1, M is Ru (ruthenium), dye dye-sensitized solar cell dye. The method of claim 1,
Dye-sensitized solar cell dye, wherein X in formula (1) is -NCS. The method of claim 1,
D in the dye-sensitized solar cell, wherein L is represented by the following formula (4):
&Lt; Formula 4 >

. The method of claim 1,
In the formula 1 Z is represented by the following formula 5 dye-sensitized solar cell dyes:
&Lt; Formula 5 >

. The method of claim 1,
In the formula 1, M is Ru (ruthenium), X is -NCS, L is a dye for a photosensitive solar cell, characterized in that the bidentate ligand represented by the following formula (2):
(2)

Wherein R ₁ and R ₂ are independently from each other selected from the group consisting of COOH, PO ₃ H ₂ , PO ₄ H ₂ , SO ₃ H ₂ , SO ₄ H ₂ and CONHOH and any one of R ₁ and R ₂ is de It is a quantized state. The method of claim 1,
In the formula 1, M is Ru (ruthenium), X is -NCS, Z is a dye for solar cells, characterized in that represented by the following formula (5):
&Lt; Formula 5 >

. The method of claim 1,
Dye-sensitized solar cell dye, comprising 70 to 99% by weight of the organometallic complex represented by the following formula (6):
(6)

. 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 positioned between the first electrode and the second electrode,
A dye-sensitized solar cell, wherein said light absorbing layer comprises semiconductor fine particles and a dye for a dye-sensitized solar cell according to any one of claims 1 to 8. 10. The method of claim 9,
The dye-sensitized solar cell, characterized in that the light absorption layer has a thickness of 1 to 15㎛.

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