KR20210116078A - Azobenzene-based Organic Dyes, Preparation Method Thereof, and Dye-sensitized Solar Cells Comprising the Same - Google Patents

Abstract

The present invention provides an azobenzene-based organic dye represented by chemical formula (1): D-π-A, and undergoes a photoisomerization reaction, a method for manufacturing the same, and a dye-sensitized solar cell using the same. In the chemical formula (1), donor (D) is (R_1)(R_2)N-, wherein R_1 and R_2 are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted cyclic C4-C10 aryl, or substituted or unsubstituted C3-C10 heteroaryl.

Description

Azobenzene-based Organic Dyes, Preparation Method Thereof, and Dye-sensitized Solar Cells Comprising the Same

The present invention relates to an azobenzene-based organic dye, a method for producing the same, and a dye-sensitized solar cell including the same, and more particularly, to an azobenzene-based organic dye that performs a photoisomerization reaction in response to an external light environment, a method for producing the same And it relates to a dye-sensitized solar cell including the same.

Recently, as the demand for energy increases, various studies on environmentally friendly solar cells are being conducted.

However, silicon solar cells have a problem of supply and demand of raw materials due to the high production cost of Si, and the battery efficiency is quite insufficient. Interest in dye-sensitized solar cells is increasing.

The dye-sensitized solar cell is a mechanism that generates electron-hole pairs by absorbing the light energy of visible light. Compared to silicon solar cells, the manufacturing cost is lower, and due to its transparent characteristics, it has the advantage that it can be applied to glass windows or glass greenhouses on the exterior walls of buildings.

In such a dye-sensitized solar cell, a photosensitizer dye is an important factor determining stability and light conversion efficiency. However, the conventionally used metal complex-based dye has a problem in that it is not environmentally friendly, including metal, and has a relatively high manufacturing cost.

Accordingly, a non-metallic organic dye having a high molar extinction coefficient and simple synthesis and separation, which is highly economical and environmentally friendly, has been proposed as an alternative.

For example, Korean Patent Application Laid-Open No. 10-2010-0136931 is used as a dye-sensitized photoelectric conversion element in a dye-sensitized solar cell and exhibits improved molar extinction coefficient, Jsc (single-circuit photocurrent density) and photoelectric conversion efficiency than conventional dyes. Although organic dyes that improve the efficiency of solar cells have been disclosed, their use is limited due to poor long-term stability.

Meanwhile, there have been efforts to solve this problem using photochromism molecules. In photochromic molecules, a change in molecular structure occurs through photoisomerization, in which a single chemical species (A) is reversibly changed to an isomer (B) with a different chemical bonding state by light of a specific wavelength, thereby showing a difference in absorption wavelength and absorbance .

In particular, azobenzene is a molecule capable of reversible trans-cis isomerization in response to light of a specific wavelength, and a stable trans-isomer is transformed into an unstable cis isomer by receiving light (the wavelength of the region absorbed by the trans-isomer), The cis isomer changes its structure to the trans isomer by light (the wavelength of the region absorbed by the cis isomer) or thermal relaxation.

However, the photoisomerization reaction of azobenzene is not easy to control, and moreover, studies for implementing excellent photochromic function by applying it to photochromic dyes and dye-sensitized solar cells are still insufficient.

Korean Patent Publication No. 10-2010-0136931

An object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

It is an object of the present invention to provide an azobenzene-based organic dye that undergoes a photoisomerization reaction in response to an external light environment.

Another object of the present invention is to provide a method for manufacturing an azobenzene-based organic dye simply and efficiently.

Another object of the present invention is to provide a dye-sensitized solar cell that implements an active photochromic function that reacts according to an external light environment, including the organic dye.

The present invention is

An azobenzene-based organic dye is provided which is represented by the following Chemical Formula (1) and undergoes a photoisomerization reaction.

D-π-A Formula (1)

In the above formula (1),

D(donor) is (R ₁ )(R ₂ )N-, wherein R ₁ and R ₂ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy , substituted or unsubstituted C4-C10 aryl, or substituted or unsubstituted C3-C10 heteroaryl;

π(π spacer) is -π ₁ -(π ₂ ) _n -,

로 표시되는 광이성질체화 기며, 여기서 상기 R₃ 및 R₄는 각각 독립적으로 수소, 할로겐 원소, 치환 또는 비치환의 C1-C4 알킬, 또는 치환 또는 비치환의 C1-C4 알콕시이고; The π ₁ is

a photoisomerization group represented by , wherein R ₃ and R ₄ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C4 alkyl, or substituted or unsubstituted C1-C4 alkoxy;

로 표시되며, 여기서 상기 R₅는 수소, 할로겐 원소, 치환 또는 비치환의 C1-C4 알킬, 또는 치환 또는 비치환의 C1-C4 알콕시이고; The π ₂ is

wherein R ₅ is hydrogen, a halogen atom, substituted or unsubstituted C1-C4 alkyl, or substituted or unsubstituted C1-C4 alkoxy;

where n is a natural number of 0 or 1;

A (acceptor) is an anchoring group (Anchoring group);

the substituent is at least one selected from the group consisting of a halogen atom, hydroxy, C1-C3 alkyl, and C1-C3 alkoxy; and

The hetero atom is at least one selected from the group consisting of N, O and S.

wherein R ₁ and R ₂ are each independently a substituted or unsubstituted C1-C5 alkyl, or a substituted or unsubstituted C6 aryl; Here, the substituent may be at least one selected from the group consisting of C1-C3 alkyl, and C1-C3 alkoxy.

R ₃ and R ₄ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C3 alkyl, or substituted or unsubstituted C1-C3 alkoxy; Here, the substituent may be at least one selected from the group consisting of C1-C2 alkyl and C1-C2 alkoxy.

wherein R ₅ is hydrogen, a halogen atom, substituted or unsubstituted C1-C3 alkyl, or substituted or unsubstituted C1-C3 alkoxy; Here, the substituent may be at least one selected from the group consisting of C1-C2 alkyl and C1-C2 alkoxy.

The anchoring group may be one or more selected from the group consisting of cyanoacrylic acid anchors, Catechol anchors, Pyridyl anchors, Phosphonate anchors, 2-Hydroxylbenzonitrile anchors, Pyridine-N-oxide anchors, Hydroxamate anchors and Sulfonate anchors. have.

The organic dye has the following cis-formula (2-1) photoisomer, trans-formula (2-2) photoisomer, cis-formula (3-1) photoisomer, trans-formula (3-2) photoisomer, cis -Chemical (4-1) photoisomer, trans-formula (4-2) and cis-formula (5-1) photoisomer, trans-formula (5-2) one or more selected from the group consisting of photoisomer can

On the other hand, the present invention, as an embodiment, is a method for producing an organic dye of formula (1) in which a photoisomerization reaction is carried out,

If n is 1,

_{(A) preparing D-π 1} -X ₂ through a Mills reaction of a compound of Formula (6) and a compound of Formula (7);

(B) Through the Suzuki-Miyaura coupling reaction of _{D-π 1} -X ₂ and B(OH) ₂ -π ₂ -CHO prepared in step (a), _{D-π 1} -π ₂ - preparing CHO; and

(C) _{coupling an anchoring group to the end through Knoevenagel condensation reaction of D-π 1} -π ₂ -CHO prepared in step (b) (in the above, n, D, π ₁ , π ₂ , A, R ₁ , R ₂ are as defined in _{claim 1,} and X _{1 and X 2} are each a halogen element); provides a method comprising a.

D-π-A Formula (1)

화학식 (6)

Formula (6)

화학식 (7)

Formula (7)

The present invention, as another embodiment, is a method for producing an organic dye of formula (1) that undergoes a photoisomerization reaction,

If n is 0,

_{(A-1) preparing D-π 1} -X ₂ through a Mills reaction of a compound of Formula (6) with a compound of Formula (7);

_{(B-1) Phosphorylation of D-π 1} -X ₂ prepared in step (A-1) and then coupling an anchoring group to the terminal through hydrolysis reaction (in the above, n, D, π ₁ , A, R ₁ , R ₂ are as defined in _{claim 1,} and X _{1 and X 2} are each a halogen element); provides a manufacturing method comprising a.

The photoisomerization reaction of the organic dye compound may be performed by irradiating light corresponding to the maximum absorption wavelength region of the photoisomerization group.

The photoisomerization reaction may be performed by irradiating light, heat, or light and heat.

The organic dye compound has a cis-trans structure conversion by a photoisomerization reaction, and the maximum absorption wavelength region of the cis-organic dye compound is an ultraviolet region, and the trans-maximum absorption wavelength region of the organic dye compound is It may be a visible light region.

On the other hand, the present invention provides a dye-sensitized solar cell comprising the organic dye.

The azobenzene-based organic dye according to the present invention can change color or transmittance through a trans-cis isomerization reaction that occurs in response to light of a specific wavelength, thereby implementing an active photochromic function that responds to external light environments.

The azobenzene-based organic dye according to the present invention is a non-metallic organic dye, which is environmentally friendly, has a low manufacturing cost, and exhibits excellent long-term stability.

According to the present invention, an azobenzene-based organic dye can be synthesized in a simple and efficient way, and a dye-sensitized solar cell having a photochromic function that actively reacts according to an external light environment can be manufactured using this.

1 is a schematic cross-sectional view of a dye-sensitized solar cell including an azobenzene-based organic dye according to the present invention;
2 is a result of measuring UV-vis absorption spectra according to DMAC of Example 1 and DPAC trans-cis of Example 2 in Experimental Examples 1-1 and 1-2, respectively; and
3 is a result of measuring the current density-voltage (JV) characteristics of the solar cell according to the DMAC of Example 1 and the DPAC trans-cis of Example 2 in Experimental Example 2;

Azobenzene-based organic dye

As described above, photosensitizer dyes are a major factor in determining the stability and light conversion efficiency of dye-sensitized solar cells, and numerous non-metal organic dyes such as coumarin-based, fluorine-based, polypyridyl-based, and porphyrin-based dyes have been developed. has been Non-metallic organic dyes have a low manufacturing cost and are environmentally friendly, but exhibit low energy conversion efficiency because they have a limited absorption area.

Accordingly, the inventors of the present invention, as will be described later after continuing in-depth research and various experiments, the color or transmittance of an azobenzene-based organic dye through a trans-cis isomerization reaction in response to light of a specific wavelength. It was confirmed that a dye-sensitized solar cell that implements an active photochromic function that reacts according to an external light environment can be manufactured using a dye-sensitized solar cell, and the present invention has been completed based on these findings.

Specifically, the present invention

An azobenzene-based organic dye represented by the following Chemical Formula (1) and undergoing a photoisomerization reaction is provided.

D-π-A formula (1)

In the above formula (1),

D(donor) is (R ₁ )(R ₂ )N-, wherein R ₁ and R ₂ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy , substituted or unsubstituted C4-C10 aryl, or substituted or unsubstituted C3-C10 heteroaryl;

π(π spacer) is -π ₁ -(π ₂ ) _n -,

로 표시되는 광이성질체화 기며, 여기서 상기 R₃ 및 R₄는 각각 독립적으로 수소, 할로겐 원소, 치환 또는 비치환의 C1-C4 알킬, 또는 치환 또는 비치환의 C1-C4 알콕시이고; The π ₁ is

a photoisomerization group represented by , wherein R ₃ and R ₄ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C4 alkyl, or substituted or unsubstituted C1-C4 alkoxy;

로 표시되며, 여기서 상기 R₅는 수소, 할로겐 원소, 치환 또는 비치환의 C1-C4 알킬, 또는 치환 또는 비치환의 C1-C4 알콕시이고; The π ₂ is

wherein R ₅ is hydrogen, a halogen atom, substituted or unsubstituted C1-C4 alkyl, or substituted or unsubstituted C1-C4 alkoxy;

where n is a natural number of 0 or 1;

A (acceptor) is an anchoring group (Anchoring group);

the substituent is at least one selected from the group consisting of a halogen atom, hydroxy, C1-C3 alkyl, and C1-C3 alkoxy; and

The hetero atom is at least one selected from the group consisting of N, O and S.

On the other hand, the terminology of the present specification will be described below.

The term “photoisomerization reaction” in a narrow sense means a reaction that causes a structural change between cis (Cis (Z))-trans (trans (E)) through an excited state by irradiation with light, and in a broad sense, photoisomerization reaction It includes not only irradiation but also reactions that cause cis-trans structure change by thermal irradiation.

The term "photoisomerization group" refers to a photosensitive functional group that causes a cis-trans structural change through an excited state by light irradiation, and in a broad sense, causes a cis-trans structural change by heat irradiation as well as light irradiation. including functional groups that cause

The term “alkyl” refers to an aliphatic hydrocarbon group. In the present invention, alkyl is "saturated alkyl" meaning that it does not contain any alkene or alkyne moiety, and "unsaturated alkyl" meaning that it contains at least one alkene or alkyne moiety. It is used as a concept that includes all of them, and in detail, may be "saturated alkyl". The alkyl may include branched, straight-chain or cyclic, and also includes structural isomers, so, for example, in the case of C3 alkyl, it may mean propyl or isopropyl.

The term “alkoxy” refers to an alkyl group as described above attached through an oxygen linkage (—O—).

The term "aryl" refers to an aromatic substituent having at least one ring with a shared pi electron system. The term includes monocyclic or polycyclic (ie, rings that share adjacent pairs of carbon atoms) groups. When substituted, the substituent may be appropriately bonded at ortho (o), meta (m), or para (p) positions.

The term “heteroaryl” is a substituent in which part of the aryl ring as described above is substituted with oxygen, nitrogen, sulfur, or the like.

The term “halogen element” is an element belonging to group 17 of the periodic table, and specifically, may be fluorine, chlorine, bromine, or iodine.

The azobenzene-based organic dye according to the present invention contains azobenzene, and since it contains an azo moiety of -N=N- structure in the photoisomerization group, it absorbs light corresponding to the maximum absorption wavelength region when irradiated with light Thus, cis-trans structure conversion can be performed. Accordingly, in the present invention, the organic dye may be interpreted as including a cis-type photoisomer (hereinafter referred to as a cis-type), a trans-type photoisomer (hereinafter referred to as a trans-type), or a mixture of a cis-type and a trans-type in any ratio. can

Specifically, the organic dye converts the trans form to the cis form when irradiated with visible light (>420 nm) or placed in a dark room, and is converted to the trans form when the cis form is irradiated with ultraviolet light (330 to 380 nm). In this case, the maximum absorption wavelength region of the compound for the cis-organic dye may be an ultraviolet region, and the maximum absorption wavelength region of the trans-organic dye compound may be a visible ray region.

The photoisomerization reaction may be performed by irradiating light corresponding to the maximum absorption wavelength region, but in some cases, heat or both light and heat may be irradiated. For example, if the cis type is irradiated with heat along with ultraviolet light, the conversion rate and conversion rate to the trans type may be increased.

The azobenzene-based organic dye according to the present invention has an excellent photochromic function according to such a photoisomerization reaction, and furthermore, the electron donor-π-electron acceptor structure represented by D-π-A allows separation and Because it promotes the movement of electrons, excellent photochromic function can be realized and long-term stability can be exhibited.

In the azobenzene-based organic dye represented by Formula (1) according to the present invention, R ₁ and R ₂ are each independently a substituted or unsubstituted C1-C5 alkyl, a substituted or unsubstituted C6 aryl; Here, the substituent may be at least one selected from the group consisting of C1-C3 alkyl, and C1-C3 alkoxy.

R ₃ and R ₄ are each independently hydrogen, a halogen atom, or substituted or unsubstituted C1-C3 alkyl or substituted or unsubstituted C1-C3 alkoxy; Here, the substituent may be at least one selected from the group consisting of C1-C2 alkyl and C1-C2 alkoxy.

wherein R ₅ is hydrogen, a halogen atom, substituted or unsubstituted C1-C3 alkyl, or substituted or unsubstituted C1-C3 alkoxy; Here, the substituent may be at least one selected from the group consisting of C1-C2 alkyl and C1-C2 alkoxy.

The anchoring group may be one or more selected from the group consisting of cyanoacrylic acid anchors, Catechol anchors, Pyridyl anchors, Phosphonate anchors, 2-Hydroxylbenzonitrile anchors, Pyridine-N-oxide anchors, Hydroxamate anchors and Sulfonate anchors. have. The structure of the anchoring group is known in the art, for example, Anchoring Groups for Dye-Sensitized Solar Cells, Lei Zhang and Jacqueline M. Cole, ACS Appl. Mater. Interfaces 2015, 7, 3427-3455.

Specifically, in the present invention, the anchoring group may be a cyanoacrylic acid anchor represented by one of the following structural formulas.

The azobenzene-based organic dye according to the present invention has the following cis-formula (2-1) photoisomer, trans-formula (2-2) photoisomer, cis-formula (3-1) photoisomer, trans-formula (3- 2) from the group consisting of photoisomer, cis-formula (4-1) photoisomer, trans-formula (4-2) and cis-formula (5-1) photoisomer, trans-formula (5-2) photoisomer It may be one or more selected.

wherein the cis-formula (2-1) photoisomer/trans-formula (2-2) photoisomer (DMAC); cis-formula (3-1) photoisomer/trans-formula (3-2) photoisomer (DPAC); Cis-formula (4-1) photoisomer/trans-formula (4-2) (DAMP) and cis-formula (5-1) photoisomer/trans-formula (5-2) (DPAP) are respectively the It is a photoisomer.

As described above, the azobenzene-based organic dye according to the present invention may include a cis type, a trans type, or a mixture of cis and trans types in any ratio. Accordingly, in detail, the azobenzene-based organic dye according to the present invention may be formed by mixing a specific compound selected from the above formula and a photoisomer thereof in an arbitrary ratio.

Azobenzene-based organic dye manufacturing method

Hereinafter, a method for preparing an azobenzene-based compound for an organic dye according to the present invention will be described.

In one embodiment, the azobenzene-based organic dye represented by the formula (1) is an organic dye in which n is 1, that is, D-π ₁ -π ₂ -A.

_{(A) preparing D-π 1} -X ₂ through a Mills reaction of the compound of Formula (6) and the compound of Formula (7);

(B) Through the Suzuki-Miyaura coupling reaction of _{D-π 1} -X ₂ and B(OH) ₂ -π ₂ -CHO prepared in step (a), _{D-π 1} -π ₂ - preparing CHO; and

(C) _{coupling an anchoring group to the end through Knoevenagel condensation reaction of D-π 1} -π ₂ -CHO prepared in step (b) (in the above, n, D, π ₁ , π ₂ , A, R ₁ , R ₂ are as defined above, and X ₁ and X ₂ are each a halogen element); may be prepared including.

D-π-A formula (1)

화학식 (6)

Formula (6)

화학식 (7)

Formula (7)

A photoisomerization group including an azo moiety of -N=N- structure may be generated through the Mills reaction in step (a).

The Suzuki-Miyaura coupling reaction in step (b) is one of the most useful methods among the methods for making an aryl-aryl bond, a transition metal catalyst such as Pd and a phosphorus derivative as a ligand, It can be carried out in a mixed solvent of water and an organic solvent using an inorganic base.

In step (c), the anchoring group is coupled to the end of _{D-π 1} -π _{2 -CHO through Knoevenagel condensation reaction.} This can be carried out using an amine such as piperidine and an organic acid such as formic acid and acetic acid in a reaction solvent such as dichloromethane, 1,2-dichloroethane, acetonitrile, tetrahydrofuran, ethyl ether, benzene, and toluene. .

The anchoring group is as defined above.

In another embodiment, the azobenzene-based organic dye represented by Formula (1) is when n is 0, that is, D-π ₁ -A of the organic dye,

_{(A-1) preparing D-π 1} -X ₂ through a Mills reaction of a compound of Formula (6) with a compound of Formula (7);

_{(B-1) Phosphorylation of D-π 1} -X ₂ prepared in step (A-1) and then coupling an anchoring group to the terminal through hydrolysis reaction (in the above, n, D, π ₁ , A, R ₁ , R ₂ are as defined above, and X ₁ and X ₂ are each a halogen element); may be prepared including.

D-π-A Formula (1)

화학식 (6)

Formula (6)

화학식 (7)

Formula (7)

A photoisomerization group including an azo moiety of -N=N- structure may be generated through the Mills reaction in step (A-1).

In the step (b-1), phosphorylation may be performed by reacting a phosphoric acid derivative and then performing a hydrolysis reaction under a strong acid to bind an anchoring group to the end of _{D-π 1} -X _{2 .}

The anchoring group is as defined above.

The photoisomerization reaction of the organic dye compound may be performed by irradiating light corresponding to the maximum absorption wavelength region of the photoisomerization group. The photoisomerization reaction may be performed by irradiating light, heat, or light and heat.

The cis-trans photoconversion of the compound for organic dye is made by a photoisomerization reaction, and the maximum absorption wavelength region of the cis-organic dye compound is the ultraviolet region, and the maximum absorption wavelength region of the trans-organic dye compound is It may be a visible light region.

Dye-sensitized solar cell

1 is a schematic cross-sectional view of a dye-sensitized solar cell including an azobenzene-based organic dye according to the present invention.

Referring to FIG. 1, the present invention provides a dye-sensitized solar cell including the azobenzene-based organic dye.

The dye-sensitized solar cell includes a first electrode (photocathode, 100), an electrolyte layer 200 formed on the first electrode 100, and a second electrode (counter electrode, 300) formed on the electrolyte layer 200. ), the first electrode 100 and the second electrode 300 are sealed to correspond, and an electrolyte is filled between the first electrode 100 and the second electrode 300 to form a dye-sensitized solar cell. produce

Each of the first electrode 100 and the second electrode 300 may be a transparent electrode, for example, a conductive metal oxide, a metal, a metal alloy, or a carbon material. Specifically, indium tin oxide (ITO), fluorine tin oxide (FTO), indium zinc oxide (ISO), antimontine oxide (ATO), fluorine doped tin oxide (FTO), platinum nanoparticles are formed FTO, SnO ₂ , ZnO, or a combination thereof; It may be platinum, silver, gold, or copper iodide, but is not limited thereto.

The electrolyte layer 200 may use a redox electrolyte. Specifically, as the electrolyte, a halogen redox electrolyte composed of a halogen compound and halogen molecules, a metal redox electrolyte such as a metal complex such as ferrocyanate-ferrocyanate, ferrocene-ferricinium ion, or cobalt complex , alkylthiol-alkyldisulfide, viologen dye, an organic redox electrolyte such as hydroquinone-quinone, and the like, and preferably a halogen redox electrolyte.

In addition, the halogen molecule may be an iodine molecule, and as the halogen compound, a _{metal halide salt such as LiI, NaI, CaI 2} , MgI ₂ , CuI, or an organic halogen such as tetraalkylammonium iodine, imidazolium iodine, pyridium iodide, etc. It may be an ammonium salt, or I ₂

In addition, the redox electrolyte may be configured in the form of a solution containing the same. In this case, as a solvent constituting the solution, a cell-chemically inactive solvent may be used. For example, acetonitrile, propylene carbonate, ethylene carbonate, 3-methoxypropionitrile, methoxyacetonitrile, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, butyrolactone, dimethoxyethane, dimethyl carbonate , 1,3-dioxolane, methyl formate, 2-methyltetrahydrofuran, 3-methoxy-oxazolidin-2-one, sulfolane, tetrahydrofuran, water, and the like. Specifically, it may be acetonitrile, propylene carbonate, ethylene carbonate, 3-methoxypropionitrile, ethylene glycol, 3-methoxy-oxazolidin-2-one, butyrolactone, and these solvents are one type or can be mixed

The electrolyte layer 200 may include a semiconductor material 210 and an azobenzene-based organic dye 220 according to the present invention. In the electrolyte layer 200, the semiconductor material 210 and the azobenzene-based organic dye 220 may have a simple mixture or a structure coated and adsorbed on any one material. Specifically, the semiconductor material 210 surface The azobenzene-based organic dye 220 may be adsorbed by generating excited electrons through absorption of light up to a near-infrared region of up to 600 to 700 nm.

The semiconductor material 210 may use a metal oxide selected from the group consisting of titanium, tin, zinc, tungsten, zirconium, gallium, indium, yttrium, niobium, tantalum, and vanadium, specifically titanium oxide, tin oxide, It may be zinc oxide, niobium oxide, strontium titanium oxide, or a mixture thereof.

The absorption characteristics of the solar cell are affected by the incident photonto-current conversion efficiency (IPCE) or light-harvesting efficiency (LHE) according to the absorption wavelength of the organic dye used. Therefore, the dye-sensitized solar cell according to the present invention can exhibit excellent photochromic function and long-term stability by including a photoelectrode carrying an organic dye with high light collection efficiency.

Hereinafter, the present invention will be described in detail through Examples, but the following Examples and Experimental Examples are merely illustrative of one aspect of the present invention, and the scope of the present invention is not limited by the Examples and Experimental Examples below. .

The azobenzene-based organic dye synthesis process according to the present invention is shown below.

Example 1 Synthesis of DMAC (R is CH ₃ )

Example 2 Synthesis of DPAC (R is C ₆ H ₅ )

1) Synthesis of 1-Bromo-4-nitrosobenzene

Dissolve 4-bromoaniline (2.5g, 14.53mmol) compound and dichloromethane (45ml) in 500mL rb-flask. Then, a substance dissolved in OXONE (8.93 g, 29.07 mmol) and distilled water (180 ml) is added. The reaction was completed at room temperature for 3.5 hours. After completion of the reaction, extraction is performed with dichloromethane. The extracted dichloromethane solution was washed with 1N HCl, saturated NaHCO ₃ solution, and distilled water. _{MgSO 4} was added to the organic layer, filtered and removed after 20 minutes, distilled under reduced pressure using an evaporator, and dried under vacuum to obtain a white solid (63%).

mp 87-89°C, FT-IR (cm ^-1 ): 3092.7; 1576.3; 1477.5; 1010.7; 820.6; 657.2. ¹ H NMR (600 MHz, CDCl ₃ ) δ 7.78 -7.77(s, 4H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 163.8; 132.7; 131.7; 122.1. MS (DIP-EI) m/z calculated for C ₆ H4BrNO, [M+H] ⁺ 187.9114

2) Synthesis of N1,N1-diphenylbenzene-1,4-diamine

Put 4-nitro-n,n-diphenyl aniline (20.84g), ethanol (300ml), and catalyst Pd/C 0.4g in 500ml rb-flask and reflux at 80°C. 15ml of N ₂ H ₄ drop by drop. The reaction mixture is refluxed for 10 hours. After completion of the reaction, the mixture was cooled to room temperature and filtered. The filtered solvent was distilled under reduced pressure and vacuum dried to obtain an impure purple solid. The obtained solid was recrystallized from ethanol to obtain a pure compound (80%).

3) Synthesis of azobenzene compound

Put the diamine compound (0.8eq) in 250ml r.b-flask, and add 100ml of AcOH:EA (1:1) solution. Then, add 1-bromo-4-nirosobenzene (1eq) and reflux at 40°C for 20 hours. After completion of the reaction, the mixture was cooled to room temperature and filtered to obtain an orange solid product.

R=Me (78%).

mp 134-136°C, FT-IR (cm ^-1 ): 2918.9; 1596.8; 1517.9; 1488.4; 1311.1; 1227.6; 1139.6; 1063.8; 1002.8; 820.4; 738.6. ¹ H NMR (600 MHz, CDCl ₃ ) δ 7.86 (d, J = 6 Hz, 2H), 7.71 (d, J = 6 Hz, 2H), 7.58 (d, J = 6 Hz, 2H), 6.74 (d) , J = 12 Hz, 2H), 3.09 (s, 6H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 152.6; 143.5; 132.1; 132.0; 127.2; 125.1; 123.9; 123.2; 111.47, 40.27. MS (DIP-EI) m/z calculated for C ₁₄ H ₁₄ BrN ₃ , [M +H] ⁺ 305.19, found 305.3605.

R=Ph (90%)

mp 135-137°C, FT-IR (cm ^-1 ): 3053.8; 1578.5; 1482.7; 1441.6; 1324.6; 1295.1; 1278.2; 1133.8; 1065.5; 1008.8; 833.0; 756.2. ¹ H NMR (600 MHz, CDCl ₃ ) δ 7.78 (d, J = 12 Hz, 2H), 7.73 (d, J = 12 Hz, 2H), 7.60 (d, J = 12 Hz, 2H), 7.32 (t) , J = 9 Hz, 4H), 7.17 (d, J = 6 Hz, 4H), 7.12 (t, J = 6 Hz, 2H), 7.09 (t, J = 6 Hz, 2H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 151.7; 150.9; 146.9; 146.8; 132.2; 129.5; 125.6; 124.4; 124.3; 124.0; 121.3; 110.0, MS (DIP-EI) m/z calculated for C ₂₄ H ₁₈ BrN ₃ , [M+H] ⁺ 429.32, found 427.3081.

4).Suzuki-Miyaura coupling reaction

2-neck-100ml of azobenzene compound (1eq), 4-formylphenylboronic acid (1.5eq), Pd(PPh ₃ ) ₄ (0.5eq), Na ₂ CO ₃ (5eq) obtained in 3. Synthesis of azobenzene compound under nitrogen atmosphere -After adding to rb-flask, dry toluene (10ml) and distilled water (5ml) are added, and refluxed under nitrogen atmosphere for 24 hours. After completion of the reaction, it was cooled to room temperature. The completed reaction is extracted with EA, washed with water and brine, and the organic solvent is _{dried over Na 2} SO ₄ for 20 minutes and filtered. The filtered solvent was distilled under reduced pressure to remove the solvent, and then purified by silica chromatography using a solvent EA:HEX=1:4 to obtain an orange solid.

R=Me (40%).

mp 151-153°C, FT-IR (cm ^-1 ): 2917.5; 1597.5; 1473.2; 1417.4; 1306.1; 1283.0; 1230.4; 1135.5; 814.6. ¹ H NMR (600 MHz, CDCl ₃ ) δ 10.06 (s, 1H), 7.97 (m, 2H), 7.91 (t, J = 18 Hz, 3H), 7.82 (d, J = 6 Hz, 1H), 7.76 (d, J = 6 Hz, 1H), 7.69 (d, J = 6 Hz, 2H), 7.37 (d, J = 6 Hz, 2H), 6.77 (d, J = 12 Hz, 2H), 3.10 (s) , 6H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 191.8; 153.1; 152.7; 146.5; 140.7; 137.0; 130.3; 128.1; 127.9; 125.2; 122.9; 116.8; 111.6; 40.3. MS (DIP-EI) m/z calculated for C ₂₁ H ₁₉ N ₃ O [M+H] ⁺ 330.40, found 330.4605.

R=Ph (31%)

mp 155-157°C, FT-IR (cm ^-1 ): 2927.7; 1699.1; 1584.8; 1486.8; 1410.2; 1337.6; 1283.3; 1216.4; 1136.3; 821.0. ¹ H NMR (600 MHz, CDCl ₃ ) δ 10.07 (s, 1H), 7.97 (dd, J = 6 Hz, J = 6 Hz, 4H), 7.83-7.81 (m, 4H), 7.77 (d, J = 12 Hz, 2H), 7.32 (t, J = 9 Hz, 4H), 7.18 (d, J = 6 Hz, 4H), 7.13 (t, J = 9 Hz, 4H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 191.8; 146.8; 146.3; 141.1; 135.4; 130.3; 129.5; 128.0; 127.7; 125.6; 124.4; 123.2; 121.4. MS (DIP-EI) m/z calculated for C ₃₁ H ₂₃ N ₃ O, [M+H] ⁺ 454.53, found 454.2750.

5). Knoevenagel condensation reaction

Into the dried 100ml rb-flask, put the carbaaldehyde derivative compound (3.3x10-2 mmol). Then, cyanoacrylic acid (8x10-1 mmol), dry THF (5ml), and piperidine (0.1ml) are added. The mixed reactants were refluxed for 15 hours. After completion of the reaction, it was cooled to room temperature. The completed reaction product was extracted with dichloromethane, the organic layer was washed with water, dried over MgSO ₄ for 20 minutes, and filtered. The filtered solvent was distilled under reduced pressure to remove the solvent, and then purified by silica chromatography using the solvent CH ₂ Cl ₂ /methanol (10:1) to obtain an orange solid.

Example 1 DMAC (R = Me (22%)

mp 195-197°C, FT-IR (cm ^-1 ): 3407.4; 2218; 1601.0; 1516.7; 1445.5; 1141.4; 822.2. ¹ H NMR (600 MHz, DMSO-d6) δ 8.02 (s, 1H), 7.97 (d, J = 12 Hz, 2H), 7.88 (t, J = 9 Hz, 3H), 7.85-7.82 (m, 2H) ), 7.80-7.76 (m, 2H), 7.52 (d, J = 6 Hz, 1H), 6.82 (d, J = 12 Hz, 2H), 3.05 (s, 6H). ¹³ C NMR (151 MHz, DMSO-d6) δ 130.5; 128.0; 127.5; 125.3; 122.9; 112.0; 40.4. MS (DIP) m/z calculated for C ₂₄ H ₂₀ N ₄ O ₂ , [M] ⁺ 397.44, found 397.0868.

Example 2 DPAC (R = Ph (23%)

mp 197-199°C, FT-IR (cm ^-1 ): 3391.6; 2359; 1584.4; 1488.3; 1332.4; 1137.2; 824.3. ¹ H NMR (600 MHz, DMSO-d6) δ 8.01 (s, 1H), 7.98 (d, J = 6 Hz, 1H), 7.91-7.87 (m, 5H), 7.81-7.78 (m, 3H), 7.53 (d, J = 6 Hz, 1H), 7.38 (t, J = 6 Hz, 4H), 7.18-7.14 (m, 6H), 6.99-6.97 (m, 2H). ¹³ C NMR (151 MHz, DMSO-d6) δ 152.2; 151.0; 146.6; 130.5; 130.3; 128.2; 127.6; 126.2; 125.3; 124.9; 123.3; 120.6. MS (DIP-EI) m/z calculated for C ₃₄ H ₂₄ N ₄ O ₂ , [M] ⁺ 520.19, found 520.1299.

Example 3 DMAP (R is CH ₃ )

Example 4 DPAP (R is Ph)

An azobenzene compound is synthesized by referring to 1) synthesis of 1-Bromo-4-nitrosobenzene, 2) synthesis of N1,N1-diphenylbenzene-1,4-diamine, and 3) synthesis of azobenzene compound of Examples 1 and 2.

4). Phosphorylation reaction

In a nitrogen atmosphere, PdCl ₂ (0.245 mmol), the azobenzene compound obtained above (0.7 mmol), and TBAB (1.051 mmol) were placed in a 100 ml 2-neck-rb flask. After adding tripropylamine (1.751 mmol) and triehtyl phosphite (2.802 mmol) to the reaction product, it was refluxed under a nitrogen atmosphere for 15 hours. After the reaction is complete, it is cooled to room temperature. Add water to the completed reaction and extract with EA. The extracted organic layer was _{dried using Na 2} SO ₄ and filtered. The filtered solvent was distilled under reduced pressure to remove the solvent, and then purified by silica chromatography using a solvent EA:HEX (1:4) to obtain an oily compound.

R=Me (65%)

¹ H NMR (600 MHz, CDCl ₃ ) δ7.92-7.88 (m, 4H); 7.60-7.56 (m, 2H); 6.75 (d,J=9.6Hz,1H) 6.59-6.57 (dd,J, 3.6,1.8Hz,1H); 4.18-4.01 (m, 4H); 3.11 (s, 4H); 1.31-1.28 (t, J = 9 Hz, 6H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 155.30; 143.9; 133.6; 125.5; 121.9; 111.4; 61.6; 40.10; 29.8; 16.3. MS (DIP-EI) m/z calculated for C1 ₈ H ₂₄ N ₃ O ₃ P, [M] ⁺ 361.0200

R=Ph (60%)

¹ H NMR (600 MHz, CDCl ₃ ) δ 7.94-7.90 (m, 4H); 7.82-7.80 (d, J = 12 Hz, 2H); 7.33-7.30 (t, J = 9 Hz, 4H); 7.18-7.17 (d, J=9.6Hz, 4H); 7.14-7.08 (m, 4H); 4.12-4.09 (q, 4H); 1.35-1.32 (t, J=9 9 Hz, 6H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 155.3; 151.3; 146.9; 132.8; 129.6; 125.8; 124.7; 122.3; 120.9; 63.6; 16.4; MS (DIP-EI) m/z calculated for C ₂₈ H ₂₈ N ₃ O ₃ P, [M ⁺ H] ⁺ 487.0100, found 485.9900.

5. Hydrolysis

Put the phosphonate compound (0.837 mmol) and HCl 2ml synthesized above in 100ml r.b-flask and reflux for 24 hours. After completion of the reaction, the product was cooled to room temperature, filtered, and dried using vacuum distillation to obtain a product.

Example 3 DMAP (R=Me (20%))

¹ H NMR (600 MHz, CDCl ₃ ) δ 7.93-7.88 (m, 6H), 6.76 (d, J=12 Hz, 2H), 3.11 (s, 6H). ¹³ C NMR (151 MHz, CDCl ₃ ) δ 155.64; 152.79; 143.64; 132.76; 125.22; 121.95; 111.43; 62.12; 40.24; 29.63; 16.39. C ₁₄ H ₁₆ N ₃ O ₃ P, [M] ⁺ 305.0929

Example 4 DPAP (R=Ph(10%))

¹ H NMR (600 MHz, CDCl ₃ ) δ 7.26-7.20(m, 6H), 7.08(d, J=4.2Hz, 1H), 7.03-6.94(m, 9H).6.89-6.87(dd,J=8.4 , 2.4, 1H), 6.71 (d, J=8.4 Hz, 1H) ¹³ C NMR (151 MHz, CDCl ₃ ) δ 147.86; 147.46; 139.44; 139.29; 138.59; 136.55; 129.25; 129.09; 127.19; 125.99; 125.46; 123.15; 122.81; 122.48; 121.96; 120.06; 119.71; 116.51. C ₂₄ H ₂₀ N ₃ O ₃ P, [M] ⁺ 429.1242

Experimental Example 1-1 DMAC

The trans-cis change of DMAC was observed by UV-Vis absorption spectrum in a solution condition of 40 μM DMAC using dimethyl formamide (DMF) as a solvent, and is shown in FIG. 2 .

Experimental Example 1-2 DPAC

The trans-cis change of DPAC was observed by UV-Vis absorption spectrum in a solution condition of 40 μM of DMAC using dimethyl formamide (DMF) as a solvent, and is shown in FIG. 2 .

In FIG. 2, the solid line represents the trans (E)-dye, and the dotted line represents the cis-(Z)-dye. A 40 μM solution of each dye was prepared using dimethyl formamide (DMF) as a solvent, and UV-Vis spectra were measured using a UV-Vis spectrophotometer (JASCO, Japan). The band gap (Eg) was calculated using the formula of Eg = 1240/λ, and is shown in Table 1 below. .

first absorption wavelength
(nm) first band gap
(eV) 2nd absorption wavelength
(nm) 2nd band gap
(eV) (E)-DMAC 329 3.77 439 2.82 (Z)-DMAC 331 3.75 452 2.74 (E)-DPAC 333 3.72 446 2.78 (Z)-DPAC 341 3.64 455 2.73

According to Table 1, it can be seen that DPAC has a greater molar extinction coefficient than DMAC.

Experimental Example 2

Dye-sensitized solar cells were prepared using Example 1 (DMAC) and Example 2 (DPAC).

A dye-sensitized solar cell was manufactured by sealing the first electrode (photocathode) and the second electrode (counter electrode) in correspondence with each other, and filling an electrolyte between the first electrode and the second electrode.

Each of the electrodes was prepared on a glass substrate. At this time, the first electrode is composed of _{fluorine-doped tin oxide (FTO) coated with titanium dioxide (TiO 2} ) nanoparticles, and the second electrode is composed of platinum (Pt) nanoparticles. It is composed of FTO, and an iodine-based liquid electrolyte (Solaronics AN-50) was used as the electrolyte.

: (Before sealing) DMAC and DPAC were prepared by adsorbing each _{of the TiO 2 of the first electrode.}

: (Before sealing) Two holes for electrolyte injection were formed in a specific part of the second electrode.

: Then, a barrier rib with a thickness of about 25 μm was placed between the first electrode and the second electrode and sealed by applying heat and pressure. As the barrier rib material, Surlyn manufactured by Solaronix was used. Then, an electrolyte solution was filled in the space between the two electrodes through the micropores formed on the surface of the second electrode and the holes were sealed to manufacture a dye-sensitized solar cell.

The current density-voltage (J-V) characteristics of the solar cells manufactured with such DMAC and DPAC were measured and the solar cell performance was evaluated. In order to compare the solar cell performance according to trans-cis photoisomerization, the cis isomer solar cell is irradiated with UV for 20 minutes or more, photochromes the trans isomer solar cell, and the current density-voltage (JV) characteristic is measured to achieve photoisomerization. The difference in solar cell performance was evaluated and shown in FIG. 3 and Table 2 below.

Voc (V) Jsc (mA/cm ² ) F.F. (%) PCE (%) (E)-DMAC 0.589 3.53 73.62 1.53 (Z)-DMAC 0.568 3.34 71.93 1.36 (E)-DPAC 0.563 1.56 74.44 0.65 (Z)-DPAC 0.560 1.47 70.79 0.58

According to FIG. 3 and Table 2, it was confirmed that photoisomerization affects the solar cell energy conversion efficiency (PCE).

Claims (12)

Azobenzene-based organic dye represented by the following formula (1) and characterized in that it undergoes a photoisomerization reaction:
D-π-A formula (1)
In the above formula (1),
D(donor) is (R ₁ )(R ₂ )N-, wherein R ₁ and R ₂ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy , substituted or unsubstituted C4-C10 aryl, or substituted or unsubstituted C3-C10 heteroaryl;
π(π spacer) is -π ₁ -(π ₂ ) _n -,
The π ₁ is

a photoisomerization group represented by , wherein R ₃ and R ₄ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C4 alkyl, or substituted or unsubstituted C1-C4 alkoxy;
The π ₂ is

wherein R ₅ is hydrogen, a halogen atom, substituted or unsubstituted C1-C4 alkyl, or substituted or unsubstituted C1-C4 alkoxy;
where n is a natural number of 0 or 1;
A (acceptor) is an anchoring group (Anchoring group);
the substituent is at least one selected from the group consisting of a halogen atom, hydroxy, C1-C3 alkyl, and C1-C3 alkoxy; and
The hetero atom is at least one selected from the group consisting of N, O and S. The method of claim 1,
wherein R ₁ and R ₂ are each independently a substituted or unsubstituted C1-C5 alkyl, or a substituted or unsubstituted C6 aryl; wherein the substituent is azobenzene-based organic dye, characterized in that at least one selected from the group consisting of C1-C3 alkyl, and C1-C3 alkoxy: The method of claim 1,
R ₃ and R ₄ are each independently hydrogen, a halogen atom, substituted or unsubstituted C1-C3 alkyl, or substituted or unsubstituted C1-C3 alkoxy; wherein the substituent is at least one selected from the group consisting of C1-C2 alkyl and C1-C2 alkoxy. The method of claim 1,
wherein R ₅ is hydrogen, a halogen atom, substituted or unsubstituted C1-C3 alkyl, or substituted or unsubstituted C1-C3 alkoxy; wherein the substituent is at least one selected from the group consisting of C1-C2 alkyl and C1-C2 alkoxy. The method of claim 1,
The anchoring group is at least one selected from the group consisting of cyanoacrylic acid anchors, Catechol anchors, Pyridyl anchors, Phosphonate anchors, 2-Hydroxylbenzonitrile anchors, Pyridine-N-oxide anchors, Hydroxamate anchors and Sulfonate anchors. Azobenzene-based organic dye characterized by its characteristics. The method of claim 1,
The organic dye has the following cis-formula (2-1) photoisomer, trans-formula (2-2) photoisomer, cis-formula (3-1) photoisomer, trans-formula (3-2) photoisomer, cis One or more selected from the group consisting of a photoisomer of formula (4-1), trans-formula (4-2) and cis-formula (5-1) photoisomer, trans-formula (5-2) photoisomer Azobenzene-based organic dye, characterized in that:

A method for producing an organic dye of formula (1), which undergoes the photoisomerization reaction according to claim 1,
If n is 1,
_{(A) preparing D-π 1} -X ₂ through a Mills reaction of a compound of Formula (6) and a compound of Formula (7);
(B) Through the Suzuki-Miyaura coupling reaction of _{D-π 1} -X ₂ and B(OH) ₂ -π ₂ -CHO prepared in step (a), _{D-π 1} -π ₂ - preparing CHO; and
(C) _{coupling an anchoring group to the end through Knoevenagel condensation reaction of D-π 1} -π ₂ -CHO prepared in step (b) (in the above, n, D, π ₁ , π ₂ , A, R ₁ , R ₂ are as defined in claim _1, and X _{1 and X 2} are each a halogen element);
A method of manufacturing a compound for an azobenzene-based organic dye, characterized in that it is prepared including a.
D-π-A formula (1)

Formula (6)

Formula (7) As a method for producing an organic dye of formula (1) that undergoes a photoisomerization reaction,
If n is 0,
_{(A-1) preparing D-π 1} -X ₂ through a Mills reaction of a compound of Formula (6) with a compound of Formula (7);
_{(B-1) Phosphorylation of D-π 1} -X ₂ prepared in step (A-1) and then coupling an anchoring group to the terminal through hydrolysis reaction (in the above, n, D, π ₁ , A, R ₁ , R ₂ are as defined in claim _1, and X _{1 and X 2} are each a halogen element);
A method for producing an azobenzene-based organic dye, characterized in that it is prepared including a. The method of claim 7 or 8, wherein the photoisomerization reaction of the compound for organic dye is performed by irradiating light corresponding to the maximum absorption wavelength region of the photoisomerization group. Way. [10] The method of claim 9, wherein the photoisomerization reaction is performed by irradiating light, heat, or light and heat. [Claim 10] The compound for organic dyes according to claim 9, wherein the organic dye compound has a cis-trans structure change by a photoisomerization reaction, and the maximum absorption wavelength region of the cis-organic dye compound is an ultraviolet region and a trans-organic dye compound. A method for producing an azobenzene-based organic dye, characterized in that the maximum absorption wavelength region is the visible ray region. A dye-sensitized solar cell comprising the organic dye according to claim 1 .

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