KR101526327B1 - Compound, dye for dye-sensitized solar cell, and a dye sensitized solar cell using the same - Google Patents

Abstract

The present invention relates to a novel compound, a dye for a dye-sensitized solar cell using the compound, and a dye-sensitized solar cell using the compound. According to the present invention, the compound has excellent short-circuit photocurrent density, fill-factors, and light conversion efficiency. According to an embodiment of the present invention, the dye-sensitized solar cell comprises: a first electrode; a second electrode; and a dye layer formed between the first electrode and the second electrode.

Description

TECHNICAL FIELD [0001] The present invention relates to a novel compound, a dye for a dye-sensitized solar cell, and a dye-sensitized solar cell comprising the dye,

The present invention relates to a novel compound, a dye for a dye-sensitized solar cell and a dye-sensitized solar cell, and more particularly, to a novel compound having improved photoelectric conversion efficiency, a dye for a dye- .

A solar cell is a device that converts light energy into electric energy by using photovoltaic effect. Unlike other energy sources, it is an energy source that is infinite in resources and environmentally friendly. It is a silicon solar cell, a dye sensitized solar cell It is known.

Silicon solar cells are difficult to put into practical use because they are expensive to manufacture, and there are many difficulties in improving efficiency. On the other hand, the dye-sensitized solar cell has a possibility to replace the conventional amorphous silicon solar cell because the manufacturing cost is significantly lower than that of the conventional silicon solar cell. The dye-sensitized solar cell is a mechanism for generating electron-hole pairs by absorbing light energy of a visible light ray. The dye-sensitized solar cell is composed of a photo-electrochemical solar cell comprising a photosensitive dye molecule and a transition metal oxide Battery.

The ruthenium complex was used as a dye for the dye-sensitized solar cell, but the ruthenium metal complex was attracted to the attention of academia because it showed energy conversion efficiency exceeding 10%. However, this ruthenium metal complex has a disadvantage of being too expensive.

In general, an organic dye which does not use a metal complex is synthesized by a structure in which an electron donor and an electron acceptor are connected by a π-bond, an electron donor is an aromatic amine derivative, an electron acceptor is 2- Cyanoacrylic acid is the most used, thiophene or phenyl group is used as the? -Conjugate, and long wavelength or short wavelength spectrum can be controlled depending on the length and conditions of the? -Conjugate.

Korean Laid-Open Publication Nos. 10-2012-0126498 and 10-2010-0136929 disclose a compound having phenocydazine as a parent nucleus, but it is necessary to develop a compound having a better photoelectric conversion efficiency.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a dye-sensitized solar cell and a dye-sensitized solar cell comprising the compound having excellent short circuit photocurrent density, filling factor, and light conversion efficiency.

In order to solve the above problems, one aspect of the present invention provides the following compounds.

In another aspect, the present invention provides a dye for a dye-sensitized solar cell comprising a compound represented by the above formula.

In another aspect, the present invention provides a liquid crystal display comprising: a first electrode; A second electrode; And a dye layer formed between the first electrode and the second electrode, wherein the dye layer includes an organic dye represented by the above formula.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a dye-sensitized solar cell and a dye-sensitized solar cell including the compound having excellent short-circuit photocurrent density, filling factor and photo-conversion efficiency of the dye-sensitized solar cell.

1 is a cross-sectional view of a dye-sensitized solar cell according to an embodiment of the present invention.
2 is a graph showing current-voltage characteristics of the dye-sensitized solar cell according to Examples and Comparative Examples of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exemplary diagram showing a schematic structure of a dye-sensitized solar cell. FIG. In general, the dye-sensitized solar cell 100 includes a transparent substrate 110, a transparent electrode 120, nanoparticles 130, a dye 140, an electrolyte, and a counter electrode 150.

That is, the dye-sensitized solar cell is composed of nanoparticles (generally, titanium oxide is used) 130 which absorbs light, which absorbs light, which generates electrons, an electrolyte, and a counter electrode 150 serving as an anode.

At this time, the dye (140) is a material directly participating in photoelectron generation. It is advantageous that the absorption occurs over the entire visible light region and the light absorption coefficient is large. The thickness of the dye polymer coating layer is well known to be monomolecular, and when molecules of two or more layers are accumulated, the efficiency is deteriorated due to interference with the transfer of electrons.

A compound according to one aspect of the present invention is represented by the following formula.

≪

In another aspect, the present invention provides a dye for a dye-sensitized solar cell comprising a compound represented by the above formula.

In another aspect, the present invention provides a liquid crystal display comprising: a first electrode; A second electrode; And a dye layer formed between the first electrode and the second electrode, wherein the dye layer includes an organic dye represented by the above formula.

Synthetic example

Hereinafter, a method for synthesizing a compound according to one aspect of the present invention will be described with reference to specific examples.

<Full Reaction Scheme>

1. Synthesis of intermediate 1

<Reaction Scheme 1>

Phenothiazine (2.37 g, 11.9 mmol), 1-bromo-4-n-octyl-benzene (4.17 g, 15.4 mmol) and sodium tert- butoxide (2.3 g, 23.8 mmol) were dissolved in 50 mL of toluene . (0.144 g, 0.7 mmol) and Pd ₂ (dba) ₃ (0.54 g, 0.59 mmol) were added to the solution, and the solution was sufficiently dissolved at room temperature under nitrogen atmosphere. When the reaction is complete, work-up is carried out with a 1: 1 mixture of water and chloroform. The organic layer after the work-up process is separated by extraction, and the solvent is removed under reduced pressure. After removing the solvent, a light yellow solid product (3.5 g, 76%) was obtained through recrystallization several times with methanol.

_{^{1 H NMR (400MHz, CDCl 3}} ): δ 7.43-7.21 (m, 4H), 7.19-7.06 (m, 4H), 7.01-6.99 (m, 4H), 2.71-2.67 (t, 2H), 1.70-1.64 (m, 2H), 1.28-1.26 (m, 6H), 0.89-0.85 (m, 7H)

2. Synthesis of intermediate 2

<Reaction Scheme 2>

Intermediate 1 (3.9 g, 1.01 mmol) produced according to Scheme 1 is dissolved in 10 mL of acetic acid, and then bromine (4.04 g, 2.53 mmol) is slowly added dropwise at 0 ° C., followed by stirring for 12 hours. When the reaction is complete, titrate with saturated sodium hydroxide in water. After the titration, work-up is carried out with a 1: 1 mixture of water and chloroform. The organic layer after the work-up process is separated by extraction, and the solvent is removed under reduced pressure. After removal of the solvent, red solid product (4.0 g, 72%) was obtained through several recrystallization steps using methanol and dichloromethane.

_{^{1 H NMR (400MHz, CDCl 3}} ): δ 7.40-7.38 (d, 2H), 7.21-7.19 (d, 2H), 7.06 (s, 2H), 6.9-6.87 (dd, 4H), 2.71-2.66 (t , J = 7.8 Hz, 2H), 1.64 (m, 2H), 1.32 (m, 6H), 0.88 (m, 3H).

3. Synthesis of intermediate 3

<Reaction Scheme 3>

Intermediate 2 (0.8 g, 0.15 mmol), Tributyl- (2,3-dihydrothieno [3,4, b] [1,4] dioxin-5-yl) stannane (1.68 g, 0.37 _{mmol), Pd (PPh 3)} 2 Cl 2 (0.06 g, 0.15 mmol) were added to 50 ml of dry THF and the mixture was refluxed at 65 ° C for 24 hours. When the reaction is complete, THF is removed and the mixture is extracted with methylene chloride and water. The dried organics were separated by column chromatography with CHCl ₃ / hexane (1: 3, v / v) to give a yellow solid product (yield: 0.3 g, 35%).

_{^{1 HNMR (400 MHz, CDCl 3}} ): δ 7.41-7.39 (d, 2H), 7.28-7.25 (d, 2H), 7.2-7.19 (d, 2H), 7.02-6.99 (dd, 4H), 6.77-6.76 (d, 2H), 6.12-6.09 (d, 2H), 2.71-2.66 (t, J = 7.8 Hz, 2H), 1.64 (m, 2H), 1.32 (m, 6H), 0.88 (m, 3H).

4. Synthesis of intermediate 4

<Reaction Scheme 4>

Intermediate 3 (0.3 g, 0.04 mmol) produced by Scheme 3 was dissolved in chloroform and DMF (0.1 g, 0.1 mmol) and 0.2 g (0.1 mmol) phosphorus oxychloride were slowly added via dropping funnel After completion of the dropwise addition, the mixture is refluxed and stirred for 8 hours. When the reaction is complete, it is poured into neutralized water and extracted with methylene chloride. Separation with ethyl acetate / hexane (1: 3, v / v) using column chromatography gave an orange solid product (yield: 0.25 g, 83.3%).

_{^{1 HNMR (400 MHz, CDCl 3}} ): δ 9.96 (s, 2H), 7.53-7.46 (d, 2H), 7.09-7.07 (d, 2H), 7.04-7.02 (m, 4H), 6.13-6.11 (d , 2H), 2.71-2.66 (t, J = 7.8 Hz, 2H), 1.64 (m, 2H), 1.32 (m, 6H), 0.88 (m, 3H).

5. Final compound synthesis

<Reaction Scheme 5>

Intermediate 4 (0.3 g, 0.7 mmol) produced in Scheme 4 was dissolved in 30 ml of acetonitrile, and 2-cyanoacrylic acid (0.13 g, 0.15 mmol) was added thereto, followed by dropwise addition of piperidine to the catalyst. Followed by reflux stirring. When the reaction is complete, pour into ice water, filter the precipitate, wash it several times with DI water and dry. The resulting dark red solid product was obtained. (Yield 0.38 g, 53%).

^{1 HNMR (400 MHz, DMSO-} d6): δ 8.22 (s, 2H), 7.49 (d, 2H), 7.42 (s, 2H), 7.31-7.29 (d, 2H), 7.22 (d, 2H), 6.05 2H), 1.64 (m, 2H), 1.32 (m, 6H), 0.88 (m, 3H).

[ Example  1] Preparation of dye-sensitized solar cell

A conductive glass substrate (FTO: TEC 8, Pilkington, 8 Ω cm 2, Thickness of 2.3 mm) was washed with ethanol using ultrasonic waves. A commercially available TiO ₂ paste (20 nm, solarnonix) was prepared. Using a doctor blade, TiO ₂ The paste was coated and fired at 500 DEG C for 30 minutes. The thickness of the fired TiO ₂ paste layer was measured by Alpha-step IQ surface profiler (KLA Tencor). Then, to use another TiO ₂ paste as a scattering layer, the fired layer was re-coated with TiO ₂ particles having a size of 400 nm and then baked at 500 ° C. for 30 minutes. Thereafter, the prepared TiO ₂ film was dried at 70 ° C. 0.04 M TiCl ₄ was immersed in an aqueous solution for 30 minutes.

Next, after the compound of the present invention was dissolved in ethanol to prepare a 0.3 mM dye solution, the annealed TiO ₂ electrode was immersed in a dye solution at 50 ° C for 3 hours to adsorb the dye.

Next, a thin film formed using a 0.7 mM H ₂ PtCl ₆ solution dissolved in 2-propanol was thermally reduced at 400 ° C for 20 minutes to prepare a Pt counter electrode (counter electrode).

Finally, the TiO ₂ electrode and the Pt counter electrode were assembled with 60 μm-thick Surlyn (Dupont 1702) as a binder, and the liquid electrolyte was injected through the perforation hole on the opposite electrode. At this time, the electrolyte was 3-propyl-1-methyl-imidazolyl iodide (PMII, 0.7M), lithium iodide (LiI, 0.2M) dissolved in acetonitrile / valeronitrile (85:15) , Iodine (I ₂ , 0.05M), t-butylpyridine (TBP, 0.5M) and the like were used.

[ Comparative Example  One]

A dye-sensitized solar cell was prepared in the same manner as in Example except that the following Comparative Compound 1 was used as a dye. The following comparative compounds are disclosed in Korean Patent Publication No. 10-2012-0126498.

<Comparative Compound 1>

[ Comparative Example  2]

A dye-sensitized solar cell was prepared in the same manner as in Example except that the following Comparative Compound 2 was used as a dye. The following comparative compounds are disclosed in Korean Patent Publication No. 10-2010-0136929.

&Lt; Comparative Compound 2 >

Table 1 shows the measurement results of the device characteristics of the dye-sensitized solar cell according to Examples and Comparative Examples of the present invention. The electric characteristics measurement conditions using the solar simulator used for the measurement were AM 1.5 (1 sun , 100 mW / cm ² ).

Dye Voc (V) Jsc (mAcm ^-2 ) FF (%) 侶 (%) Example 1 0.688 22.63 71.75 11.17 Comparative Example 1 0.708 21.0 61.2 9.1 Comparative Example 2 0.644 18.8 68.5 8.3

In Table 1, Jsc is short-circuit photocurrent density, Voc is opencircuit photovoltage, ff is a fill factor, and? Indicates the total photoconversion efficiency. At this time, the performance of the dye-sensitized solar cell was measured with a working area of 0.24 cm ² .

As shown in Table 1, when a compound according to an embodiment of the present invention was used as a dye of a dye-sensitized solar cell, the short-circuit photocurrent density, the charge factor and the light conversion efficiency were significantly improved as compared with Comparative Example 1 and Comparative Example 2 Can be confirmed.

In other words, when the present invention is compared with Comparative Example 1, even if an ethynyl group substituted with cyano group and carboxyl group is bonded to the same position of thiophene in the structure skeleton of phenothiazine-substituted thiophene, a hexyl group It can be seen that the photoconversion efficiency of the combined embodiment of the present invention is improved by about 23%. Compared with the comparative example 2, even if it has a similar compound structure skeleton, a hexyl group bonded to phenyl bonded to N of phenocylazin When the compound of Example of the present invention is used as a dye, the photoconversion efficiency is improved by about 35%. Therefore, according to the present invention, not only the photo-conversion efficiency is remarkably improved, but also the short-circuit photocurrent density and the filling factor can be remarkably improved.

This characteristic of the present invention can be confirmed from FIG. FIG. 2 is a graph showing the current-voltage characteristics of the dye-sensitized solar cell according to an embodiment of the present invention, Comparative Example 1 and Comparative Example 2. In the present invention, Voc (open-circuit voltage) And Jsc (short-circuit current) are improved, and the short-circuit current characteristics are improved as compared with Comparative Example 1. As a result, it is confirmed that the light conversion efficiency is improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention. It will be understood by those skilled in the art that various changes may be made and equivalents may be resorted to without departing from the scope of the appended claims.

100: dye-sensitized solar cell 110: transparent substrate
120: transparent electrode 130: nanoparticle
140: dye 150: counter electrode

Claims (3)

A compound represented by the formula:

. A dye for a dye-sensitized solar cell comprising the compound of claim 1. A first electrode; A second electrode; And a dye layer formed between the first electrode and the second electrode, the dye sensitized solar cell comprising:
The dye-sensitized solar cell according to claim 1, wherein the dye layer comprises the compound of claim 1.

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