KR20120007172A - New imidazolium salts and electrolyte composition for dye-sensitized sollar cells containing the salt - Google Patents

Abstract

PURPOSE: An electrolyte composition for dye-sensitized solar cells containing a novel imidazolium salt is provided to ensure excellent ion conductivity. CONSTITUTION: An electrolyte composition for dye-sensitized solar cells contains imidazolium salt and iodine. The imidazolium salt is denoted by chemical formula 1. In chemical formula 1, R1 is alkyl group or vinyl group of C1-C10; R2 is H or alkyl group of C1-C3; and n1 is 1-5 integer. The iodine is contained in 0.5-10 wt% of the imidazolium salt. The composition additionally contains acetonitrile, 3-methoxy propionitrile, valeronitrile, ethylene carbonate, propylene carbonate, gamma-butyrolactoen, or N-methyl-2-pyrrolidone.

Description

New imidazolium salts and electrolyte composition for dye-sensitized solar cells containing the same

The present invention relates to an imidazolium salt having a property of a room temperature ionic liquid having excellent ion conductivity and an electrolyte composition for dye-sensitized solar cells containing the imidazolium salt having excellent light conversion efficiency and improving safety and durability.

In recent years, extensive research has been conducted to harness natural energy such as wind, nuclear power and solar power, which can replace petroleum resources that will be exhausted within decades to solve the energy problem. Of these, solar cells using solar energy have been in the limelight since their development in 1983 because of their infinite resources and environmental friendliness. The first solar cell developed is a silicon solar cell, the manufacturing cost is very expensive, it is difficult to put practical use, and there are many difficulties in improving the cell efficiency. In order to overcome this problem, solar cells have recently been developed based on dye-sensitized solar cells, which are significantly cheaper to manufacture.

Solar cells, published in 1991 by Gratzel et al., Switzerland, are representative examples of dye-sensitized solar cells known to date. The solar cell by Gratzel et al. Is a semiconductor electrode of a metal oxide coated with a photosensitive dye molecule capable of absorbing visible light to produce an electron-hole pair, an opposite electrode including a platinum catalyst, and an electrolyte filled therebetween. Consists of

Among the components, the electrolyte plays a role of transporting electrons between the semiconductor electrode and the counter electrode, and is a key factor in determining the photoelectric efficiency and durability of the solar cell. In the conventional dye-sensitized solar cell, a liquid electrolyte using a volatile organic solvent was mainly used. Liquid electrolytes have excellent ionic conductivity and excellent light conversion efficiency.However, when the temperature of solar cell is increased by sunlight, solvent of electrolyte may be volatilized from the solar cell. This low value acts as a problem in the practical use of solar cells.

In order to solve this problem, semi-solid electrolytes have been developed, and through this, it is possible to some extent improve the volatility or leakage potential of the conventional liquid electrolyte. The semi-solid electrolyte may be formed by adding a plasticizer to the polymer for forming an electrolyte, by adding an organic monomolecule gelling agent to a liquid electrolyte, by using a polymerized or crosslinked reaction of an organic monomolecule, or by using a hydrogen bond group. Methods of using molecules are known. However, the semi-solid electrolyte prepared according to the above methods is poor in stability to temperature rise, lacks adhesion to the metal oxide layer, and satisfies the ion conductivity characteristics by disturbing the migration path of electrons generated from the redox pair in the electrolyte. There is plenty of room for improvement, such as not reaching the level.

Recently, research is being conducted to replace the existing electrolyte by using room temperature ionic liquid (RTIL). Unlike ionic salt compounds consisting of metal cations and non-metal anions, usually melting at high temperatures above 800 ° C, ionic salts that exist as liquids at temperatures below 100 ° C are called ionic liquids, especially ionic liquids that exist as liquids at room temperature. The liquid is called room temperature ionic liquid (RTIL). Room temperature ionic liquids have several advantages such as (1) chemical stability, (2) electrochemical stability with relatively wide potential window, (3) high ion conductivity, (4) low melting point, and (5) thermal stability. It is replacing the electrolyte. In addition, the room temperature ionic liquid is a room temperature melting type, there is no volatility, there is no problem due to volatilization. A reduction-sensitized solar cell has a visible light transmission of excited electrons in the dye receiving light of a metal oxide, such as the n-type semiconductor, titanium dioxide, and I that is included in the liquid ^electrolyte electrochemical oxidation of the ^- / I ₃ By regenerating the dye, current is generated. Typical room temperature ionic liquids include imidazolium-based compounds, and derivatives having a carbon chain of C 3 or more at position 3 of imidazolium are known to have ionic molten salt properties. However, since the room temperature ionic liquid according to the prior art still lacks the ionic conductivity, it is urgent to develop a more efficient electrolyte.

Silicon (Si) is an element having characteristics of a semiconductor. When silicon is introduced into a molecule, silicon (Si) tends to have a physical property of a liquid even when its molecular weight is increased due to a lower melting point, and ionic conductivity is expected to be improved due to the characteristics of a semiconductor. Using this property, a silicon compound was introduced into the imidazolium salt to develop a new compound having excellent ionic conductivity and having properties of room temperature ionic liquid to complete the present invention.

The present invention aims to provide a novel imidazolium salt with excellent ion conducting properties in order to solve the problems of the prior art.

In addition, another object of the present invention is to provide an electrolyte composition for dye-sensitized solar cells that can contain the imidazolium salt to increase durability and efficiency of dye-sensitized solar cells.

Still another object of the present invention is to provide a dye-sensitized solar cell having excellent light conversion efficiency and improved lifespan using the electrolyte composition.

The present invention for achieving the above object relates to an imidazolium salt represented by the formula (1).

[Formula 1]

At this time, R ₁ is an alkyl group of C1-C10 or Vinyl group; R ₂ is H or a C1-C3 alkyl group, n ₁ is an integer of 1 to 6; n ₂ is an integer of 1 to 3.

Another aspect of the present invention relates to an electrolyte composition for dye-sensitized solar cells, comprising an imidazolium salt represented by Formula 1 and iodine.

In this case, iodine reacts with an anion in a solution of the ammonium imidazolium salt of formula 1 to generate I ⁻ and I ^{3 −} ions and regenerates the photosensitive dye by redox reaction. It is preferable that the said iodine is melt | dissolved in 0.5-10 weight% of the weight of an imidazolium salt. If the amount of iodine is too small, the regeneration by electron transfer to the dye molecule by the redox reaction is not efficient, and if the amount of iodine is too large, the amount of imidazolium salt is relatively small so that the ion conduction is efficient. As a result, the efficiency of the solar cell is lowered.

The imidazolium salt of Chemical Formula 1 is a liquid state at room temperature and is composed of organic cations and anions, so that dye-sensitized solar cells may be mixed with ionic or other ionic molten salts by themselves or as a mixture even without an organic solvent. Can be used as an electrolyte.

The electrolyte composition may further contain a nonvolatile or low volatile organic solvent to adjust the viscosity. The organic solvent may be a nitrile solvent such as acetonitrile, 3-methoxy propionitrile, valeronitrile, ethylene carbonate, propylene carbonate, or the like. Carbonate-based solvents such as gamma-butyrolatone, γ-butyrolatone, N-methyl-2-pyrrolidone, and the like, and the like, but are not limited thereto. Anything can be used. The organic solvent is preferably used from 0 to 10 times the weight of the imidazolium compound. Since the imidazolium compound of this invention can be used even without a solvent, a minimum has no meaning. However, if the use ratio of the organic solvent is too high, it is preferable to use an organic solvent of 10 times or less since the electrolyte solution does not exhibit sufficient conductivity.

Another embodiment of the present invention relates to a dye-sensitized solar cell to which the electrolyte composition for dye-sensitized solar cell is applied. That is, the present invention relates to a dye-sensitized solar cell, wherein the electrolyte composition of the present invention is filled between a semiconductor electrode and a counter electrode made of a metal oxide adsorbed with a photosensitive dye. Those skilled in the art will not be able to construct the dye-sensitized solar cell of the present invention with reference to the prior art, and the present invention is not limited by the specific structure or manufacturing method of the dye-sensitized solar cell, and thus the detailed description thereof will be omitted. .

As described above, the imidazolium compound of the present invention is excellent in ionic conductivity and can provide a dye-sensitized solar cell having high light conversion efficiency when prepared as an electrolyte composition. The electrolyte composition is present in a liquid state in a wide range of room temperature and high temperature, and excellent in thermal stability and there is no fear of volatilization, thus making it possible to manufacture a dye-sensitized solar cell that can be used for a long time.

The present invention will be described in detail through the following examples. However, these examples are for illustrative purposes only and the present invention is not limited thereto. In addition, it will be apparent to those skilled in the art that various modifications and changes can be made within the scope of the present invention based on these examples.

< Example >

Preparation Example: Preparation of Imidazolium Salt

The compound of manufacture examples 1-14 of Table 1 was manufactured by the following method.

Preparation Example 1

1) Coupling of BMDS and 1-methyl imidazole

1,3-Bis (chloromethyl) tetramethyl-disiloxane (BMDS) 3g (12.97mmol, Aldrich) was dissolved in 30mL of acetonitrile, and 3.19g (38.91mmol, Aldrich) of 1-methylimidazole was added and stirred for 48 hours. After refluxing for 48 hours, the reaction solution was concentrated under reduced pressure, and the residue was washed three times with THF in order to remove 1-methylimidazole remaining without reaction. After washing, the residue was concentrated under reduced pressure to obtain 4.62 g (yield 90%) of liquid.

2) Preparation of Iodine Salt

3 g (7.59 mmol) of the liquid obtained in 1) was dissolved in 40 mL of acetonitrile, and 4.54 g of NaI (30.34 mmol, Aldrich) was added thereto, and the mixture was refluxed with stirring for 24 hours. After reflux, the reaction solution was filtered under reduced pressure, and the filtrate was concentrated under reduced pressure. To remove NaI from the concentrated residue, the residue was washed with THF, and the reaction solution was concentrated under reduced pressure to obtain 2.70 g of a brown liquid. (Yield from BMDS: 80%)

¹ H NMR (400 MHz; DMSO _d6 ): 9.12 ppm (s, 2H), 7.74 ppm (d, 2H), 7.67 ppm (d, 2H), 3.79 ppm (s, 4H), 3.75 ppm (s, 6H) , 0 ppm (s, 12H).

Production Example 2

1) 1,5- bis ( chloromethyl ) -1,1,3,3,5,5- hexamethyl Trisiloxane ( BMTS ) Synthesis

4.7 g (46.49 mmol) of triethylamine, 0.9 mL (49.98 mmol) of distilled water, 70 mL of Ethyl ether, and 7 mL of Acetone were mixed, cooled to 0 ° C, and maintained at a temperature of 3 g (23.25 mmol) of Dichlorodimethylsilane in 30 mL of Ethyl ether. Slowly added dropwise over time. After the addition was completed, the mixture was further stirred at 0 ° C. for 30 minutes, and then filtered under reduced pressure to remove Triethylamine Hydrochloride. 10 mL of Hexane was added to the filtrate, and the resulting crystal was concentrated under reduced pressure at 1/10. The resulting crystals were filtered and washed with cold Hexane to obtain 1.76 g (82%) of crystalline dimethylsilanediol.

3 g (32.55 mmol) of dimethylsilanediol was diluted in 30 mL of Ethylether. 11.18 g (78.12 mmol) of chlororo (chloromethyl) dimethylsilane was dissolved in 20 mL of Ethylether, stirred at 0 ° C., and the dimethylsilanediol dilution prepared above was slowly added dropwise over 1 hour. After the addition was completed, the mixture was further stirred at 0 ° C. for 30 minutes and concentrated under reduced pressure. 8.45 g (85% yield) of BMTS was separated and purified from the concentrated residue using silica gel column chromatography (Ethylacetate: Hexane 1: 9).

2) Coupling of BMTS and 1-methyl imidazole

3M (9.82 mmol) of BMTS prepared in 1) was used instead of BMDS and 2.42 g (29.46 mmol) of 1-methylimidazole was used in the same manner as in Example 1, to prepare a liquid coupling product. Got it.

3) Preparation of Iodine Salt

In the same manner as in Preparation Example 1 2) using 3g (6.39mmol) and NaI 3.83g (25.55mmol) in the liquid obtained in 2) 4.93g of the compound of Preparation Example 2 was prepared in 77% yield from BMTS.

¹ H NMR (400 MHz; DMSO _d6 ): 9.12 ppm (s, 2H), 7.74 ppm (d, 2H), 7.67 ppm (d, 2H), 3.79 ppm (s, 4H), 3.75 ppm (s, 6H) , 0 ppm (s, 18H).

Manufacturing example  3

4.83 g (38.91 mmol, 1-butylimidazole instead of 1-methylimidazole, Coupling was carried out by the same method as 1) of Preparation Example 1, except that Aldrich) was used.

3.73 g of the compound of Preparation Example 3 was prepared in the same manner as in 2) of Preparation Example 1 using 3 g (6.25 mmol) and NaI 3.75 g (25.02 mmol) in the liquid obtained by the coupling in 80% yield from BMTS.

¹ H NMR (400 MHz; DMSO _d6 ): 9.12 ppm (s, 2H), 7.75 ppm (d, 2H), 7.67 ppm (d, 2H), 3.79 ppm (s, 4H), 3.77 ppm (t, 4H) , 1.78-1.79 ppm (m, 4H), 1.33-1.34 ppm (m, 4H), 0.98 ppm (t, 6H), 0 ppm (s, 12H).

Preparation Example 4

3.66 g (38.91 mmol, 1-Vinyl imidazole instead of 1-methylimidazole, Coupling was carried out by the same method as 1) of Preparation Example 1, except that Aldrich) was used.

3.88 g of the compound of Preparation Example 4 was prepared in the same manner as in 2) of Preparation Example 1 using 3 g (7.15 mmol) of NaI and 4.29 g (28.61 mmol) in the liquid obtained by the coupling in 80% yield from BMTS.

¹ H NMR (400 MHz; DMSO _d6 ): 9.12 ppm (s, 2H), 7.74 ppm (d, 2H), 7.68 ppm (d, 2H), 5.42 ppm (t, 2H), 5.13 ppm (d, 4H) , 3.79 ppm (s, 4H), 0 ppm (s, 12H).

Preparation Example 5

Coupling was carried out by the same method as 1) of Preparation Example 1, except that 3.74 g (38.91 mmol, Aldrich) of 1,2-dimethylimidazole was used instead of 1-methylimidazole.

3.86 g of the compound of Preparation Example 5 was prepared in the same manner as in 2) of Preparation Example 1 using 3 g (7.08 mmol) of NaI and 4.25 g (28.33 mmol) of the liquid obtained by the coupling in 80% yield from BMTS.

¹ H NMR (400 MHz; DMSO _d6 ): 7.74ppm (d, 2H), 7.68ppm (d, 2H), 3.79ppm (s, 4H), 3.75ppm (s, 6H), 2.42ppm (s, 6H) , 0 ppm (s, 12H).

Preparation Example 6

Coupling was carried out by the same method as 2) of Preparation Example 2, except that 3.78 g of 1,2-dimethylimidazole (39.29 mmol, Aldrich) was used instead of 1-methylimidazole.

2.95 g of the compound of Preparation Example 6 was prepared in the same manner as in 3) of Preparation Example 2 using 3 g (6.03 mmol) of NaI and 3.62 g (24.12 mmol) of the liquid obtained by coupling in 72% yield from BMTS.

¹ H NMR (400 MHz; DMSO _d6 ): 7.74ppm (d, 2H), 7.68ppm (d, 2H), 3.79ppm (s, 4H), 3.76ppm (s, 6H), 3.75ppm (s, 6H) , 0 ppm (s, 18H).

Preparation Example 7

Coupling was carried out by the same method as 1) of Preparation Example 1, except that 8.65 g (38.91 mmol, Aldrich) of 1-decyl-2-methylimidazole was used instead of 1-methylimidazole.

2.70 g of the compound of Preparation Example 7 was prepared in the same manner as in 2) of Preparation Example 1 using 3 g (4.44 mmol) of NaI and 2.66 g (17.75 mmol) in the liquid obtained by the coupling in 80% yield from BMTS.

¹ H NMR (400 MHz; DMSO _d6 ): 7.75 ppm (d, 2H), 7.68 ppm (d, 2H), 3.79 ppm (s, 4H), 3.76-3.78 ppm (t, 4H), 2.42 ppm (s, 6H), 1.79-1.82 (m, 4H), 1.26-1.31 (m, 28H), 0.89 ppm (t, 6H), 0 ppm (s, 12H).

Manufacturing example  8

1) 1,5- Bis (3- chloropropyl ) -1,1,3,3,5,5- hexamethyl Preparation of trisiloxane ( BPTS )

In nitrogen atmosphere, 1,1,3,3,5,5-Hexamethyl Trisiloxane 3g (14.39mmol, Aldrich) and Allyl alcohol 3.91mL (57.56mmol, Aldrich) were dissolved in 30mL of Toluene, followed by Platinum (0) -1, 0.05 mL (Aldrich) of 3-divinyl-1,1,3,3-tetra methyl disiloxane complex was added and reacted by refluxing with stirring for 12 hours. After 12 hours, the reaction solution was concentrated under reduced pressure, and the residue was dissolved in 30 mL of methanol and filtered through a cellite under reduced pressure. The filtrate was concentrated under reduced pressure to obtain 4.20 g of 1,5-bis (3-hydroxypropyl) -1,1,3,3,5,5-hexamethyl trisiloxane in a transparent liquid state (yield 95%).

3 g (9.24 mmol) of 1,5-bis (3-hydroxypropyl) -1,1,3,3,5,5-hexamethyl trisiloxane prepared by the above reaction was cooled to 0 ° C and 6.74 mL (92.41 mmol) of thionyl chloride And pyridine 0.074mL (0.92mmol) was slowly added dropwise and stirred for 30 minutes. When the addition was completed, the mixture was heated to reflux for 6 hours and reacted. After refluxing, the reaction solution was concentrated under reduced pressure to remove residual thionyl chloride. The reaction solution was poured into 100 mL of distilled water and stirred for 30 minutes. Thereafter, 50 mL of ethyl acetate was added thereto, followed by stirring. The ethyl acetate layer was extracted using a separatory funnel. The extraction was repeated three times, and the ethyl acetate layers were combined and washed sequentially using 100 mL of NaHCO ₃ supersaturated solution and 100 mL of brine. After washing, the organic layer was removed using Na ₂ SO ₄ , filtered, and the filtrate was concentrated under reduced pressure at 60 ° C. to give 1,5-bis (3-chloroppropyl) -1,1,3 as a pale brown liquid. 2.84 g of, 3,5,5-hexamethyl trisiloxane (BPTS) were obtained (yield 85%).

2) Coupling of BPTS and 1-methyl imidazole

BPTS 3g (8.30mmol) obtained in 1) was dissolved in 30mL of acetonitrile, and 1-methylimidazole 1.98mL (24.90mmol) was added thereto, and the mixture was refluxed for 48 hours. After refluxing for 48 hours, the reaction solution was concentrated under reduced pressure, and the residue was washed three times with THF in order to remove 1-methylimidazole remaining without reaction. After washing, the residue was concentrated under reduced pressure to obtain 3.49 g of a dark brown viscous liquid. (Yield 80%)

3) Preparation of Iodine Salt

3 g (5.71 mmol) of the liquid obtained in 2) was dissolved in 40 mL of acetonitrile, and then 3.42 g (22.84 mmol) of NaI were added and refluxed with stirring for 24 hours. After reflux, the reaction solution was filtered under reduced pressure, and the filtrate was concentrated under reduced pressure. To remove NaI from the concentrated residue, the residue was washed with THF and the reaction solution was concentrated under reduced pressure. (Yield: 90%)

¹ H NMR (400 MHz; DMSO _d6 ): 9.12ppm (s, 2H), 7.74ppm (d, 2H), 7.67ppm (d, 2H), 4.10ppm (t, 4H), 3.81ppm (s, 6H) , 1.67-1.75 ppm (m, 4H), 0.38 ppm (t, 4H), 0 ppm (s, 18H).

Manufacturing example  9

Coupling was carried out by the same method as 2) of Preparation Example 8, except that 3.09 g (24.90 mmol) of 1-butylimidazole was used instead of 1-methylimidazole.

4.94 g of the compound of Preparation Example 9 was prepared in the same manner as in 3) of Preparation Example 8 using 3 g (4.92 mmol) of NaI and 2.95 g (19.68 mmol) in the liquid obtained by coupling in 72% yield from BPTS.

¹ H NMR (400 MHz; DMSO _d6 ): 9.12 ppm (s, 2H), 7.74 ppm (d, 2H), 7.68 ppm (d, 2H), 4.10 ppm (t, 4H), 3.82 ppm (t, 4H) , 1.77-1.82 ppm (m, 4H), 1.67-1.75 ppm (m, 4H), 1.33-1.39 ppm (m, 4H), 0.98 ppm (t, 6H), 0.38 ppm (t, 4H), 0 ppm (s , 18H).

Preparation Example 10

Coupling was carried out by the same method as 2) of Preparation Example 8, except that 2.39 g (24.85 mmol) of 1,2-dimethylimidazole was used instead of 1-methylimidazole.

4.48 g of the compound of Preparation Example 10 was prepared in the same manner as in 3) of Preparation Example 8 using 3 g (5.42 mmol) and NaI 3.25 g (21.67 mmol) in the liquid obtained by the coupling in 70% yield from BPTS.

¹ H NMR (400 MHz; DMSO _d6 ): 7.74ppm (d, 2H), 7.68ppm (d, 2H), 4.10ppm (t, 4H), 3.81ppm (s, 6H), 2.42ppm (s, 6H) , 1.67-1.75 ppm (m, 4H), 0.39 ppm (t, 4H), 0 ppm (s, 18H).

Manufacturing example  11

Coupling was carried out by the same method as 2) of Preparation Example 8, except that 5.54 g (24.85 mmol) of 1-decyl-2-methylimidazole was used instead of 1-methylimidazole.

6.16 g of the compound of Preparation Example 11 was prepared in the same manner as in 3) of Preparation Example 8 using 3 g (3.72 mmol) and NaI 2.23 g (14.88 mmol) in the liquid obtained by the coupling in 75% yield from BPTS.

¹ H NMR (400 MHz; DMSO _d6 ): 7.75 ppm (d, 2H), 7.67 ppm (d, 2H), 4.10 ppm (t, 4H), 3.77 ppm (t, 4H), 2.42 ppm (s, 6H) , 1.79-1.82 (m, 4H), 1.67-1.75 ppm (m, 4H), 1.26-1.31 (m, 28H), 0.89 ppm (t, 6H), 0.39 ppm (t, 4H), 0 ppm (s, 18H ).

Production Example 12

1) 1,5- Bis (3- chlorohexyl ) -1,1,3,3,5,5- hexamethyl Manufacture of trisiloxane

1,5-bis (3-chlorohexyl) -1 in a pale brown liquid state by the same method as 1) in Preparation Example 8, except that 6.91 mL (57.56 mmol) of 5-hexen-1-ol was used instead of allyl alcohol. 5.01 g of 1,3,3,5,5-hexamethyltrisiloxane (BHTS) Obtained (yield 79%).

2) Coupling of BHTS and 1-methyl imidazole

After dissolving 3 g (6.73 mmol) of BHTS obtained in 1) in 30 mL of acetonitrile, 1.61 mL (20.19 mmol) of 1-methylimidazole was added thereto, and the mixture was refluxed for 48 hours. After refluxing for 48 hours, the reaction solution was concentrated under reduced pressure, and the residue was washed three times with THF in order to remove 1-methylimidazole remaining without reaction. After washing, the residue was concentrated under reduced pressure to give 3.28 g of a dark brown viscous liquid.

3) Preparation of Iodine Salt

3 g (4.92 mmol) of the liquid obtained in 2) was dissolved in 40 mL of acetonitrile, and then 2.95 g (19.68 mmol) of NaI were added and stirred under reflux for 24 hours. After reflux, the reaction solution was filtered under reduced pressure, and the filtrate was concentrated under reduced pressure. To remove NaI from the concentrated residue, the residue was washed with THF, and the reaction solution was concentrated under reduced pressure to prepare 3.73 g of the compound of Preparation 12 in 70% yield from BHTS.

¹ H NMR (400 MHz; DMSO _d6 ): 9.12ppm (s, 2H), 7.75ppm (d, 2H), 7.67ppm (d, 2H), 4.10ppm (t, 4H), 3.81ppm (s, 6H) , 1.65-1.74ppm (m, 4H), 1.54-1.58ppm (m, 4H), 1.42-1.47ppm (m, 4H), 1.23-1.28ppm (m, 4H), 0.97ppm (t, 4H), 0ppm (s, 18 H).

Preparation Example 13

Coupling was carried out by the same method as 2) of Preparation Example 12, except that 2.12 g (22.01 mmol) of 1,2-dimethylimidazole was used instead of 1-methylimidazole.

3 g (4.70 mmol) and 2.82 g (18.80 mmol) NaI in the liquid obtained by coupling 3.87 g of the compound of Preparation Example 13 was prepared in the same manner as in 3) of Preparation Example 12 using BHTS in a yield of 70%.

¹ H NMR (400 MHz; DMSO _d6 ): 7.75ppm (d, 2H), 7.67ppm (d, 2H), 4.10ppm (t, 4H), 3.81ppm (s, 6H), 2.42ppm (s, 6H) , 1.65-1.74 ppm (m, 4H), 1.54-1.58 ppm (m, 4H), 1.42-1.47 ppm (m, 4H), 1.23-1.28 ppm (m, 4H), 0.99 ppm (t, 4H), 0 ppm (s, 18 H).

Preparation Example 14

Coupling was carried out by the same method as 2) of Preparation Example 12, except that 4.90 g (22.01 mmol) of 1-decyl-2-methylimidazole was used instead of 1-methylimidazole.

5.42 g of the compound of Preparation Example 13 was prepared in the same manner as in 3) of Preparation Example 12 using 3 g (3.37 mmol) and NaI 2.02 g (13.48 mmol) in the liquid obtained by the coupling in 75% yield from BHTS.

¹ H NMR (400 MHz; DMSO _d6 ): 7.75 ppm (d, 2H), 7.68 ppm (d, 2H), 4.11 ppm (t, 4H), 3.77 ppm (t, 4H), 2.42 ppm (s, 6H) , 1.79-1.82 (m, 4H), 1.65-1.74 ppm (m, 4H), 1.54-1.58 ppm (m, 4H), 1.42-1.47 ppm (m, 4H), 1.26-1.31 (m, 28H), 1.23 -1.28 ppm (m, 4H), 0.97 ppm (t, 4H), 0.89 ppm (t, 6H), 0 ppm (s, 18H).

Example I Preparation of Solution Phase Electrolyte Composition

Acetonitrile (ACN) or 3-methoxy propionitrile so that the total volume is 1 L of the imidazolium salt 0.6M, 0.1M guanidinium thiocyanate, 0.03MI ₂ and 0.5M 4- tert -butyl pyridine described in Table 2 below It was dissolved in (MPN) to prepare an electrolyte solution. In Table 2 below, DMII represents 1,3-dimethyl imidazolium iodide.

Example II  : Solvent free  Preparation of Electrolyte Composition

Solvent electrolyte composition was prepared by mixing 20 M imidazolium salt, 0.2 M guanidinium thiocyanate, 1 MI ₂ and 1 M NMB (1-methylbenzimidazole) described in Table 3 below.

Measurement of efficiency characteristics of solar cell

1) Manufacture of Solar Cell

(1) Preparation of Cathode Semiconductor Electrode

A nanoparticle titanium dioxide paste (20nm TiO ₂ paste, CCIC, Japan) was coated on a transparent conductive glass substrate (pilkington glass, USA) coated with ITO or SnO ₂ to a thickness of about 12 to 13 μm, and then about 450 It was heated for 3 hours at a temperature of ~ 550 ℃ to contact and fill the nanoparticle oxides. Dye solution consisting of ruthenium complex on the glass substrate coated with nanoparticle titanium dioxide (N719, 0.3 mM in ethyl alcohol) After soaking for 24 hours, a semiconductor electrode including a transition metal oxide layer adsorbed with a dye was completed.

(2) Preparation of the anode counter electrode

On the transparent conductive glass substrate coated with ITO or FTO, a counter electrode was prepared by coating a platinum layer with an isopropyl alcohol solution having a concentration of 20 mM H ₂ PtCl ₆占 xH ₂ O (aldrich). Using a hand drill, two micro holes about 1 mm in diameter were formed to penetrate the counter electrode.

(3) Assembly of Dye-Sensitized Solar Cell

The semiconductor electrode and the counter electrode manufactured in (1) and (2), respectively, were made to face the transition metal oxide layer and the platinum layer, and the sulyn (Du Pont Co.) 100 The two electrodes were bonded together by a clip on a heating plate at ˜150 ° C.

Thereafter, one of the electrolyte compositions prepared in Examples 1 to 41 or Comparative Examples 1 to 11 was filled in the space between the two electrodes through the minute hole formed on the surface of the counter electrode. When the electrolyte was filled, the pores on the surface of the counter electrode were sealed by instantaneous heating and adhesion using sulyn (Du Pont) and cover glass.

2) Measurement of efficiency characteristics of solar cell

The solar cell fabricated in 1) was irradiated with 100mW / ㎠ solar radiation light source using 300W xenon lamp equipped with AM 1.5 global filter. At this time, the energy conversion efficiency (η) from the photocurrent density (J _sc ), the short circuit voltage (V _oc ), and the fill factor formed was measured using a Newport / Oriel Solar Simulator (class 3A, model: 94083A). The results are shown in Tables 4 and 5 below.

Table 4 is a table showing the light conversion efficiency of the solar cell using a solution electrolyte composition, 6.1 to 7.5% for a solar cell using an electrolyte solution containing an imidazolium prepared in the above production example (Examples 1 to 14) It showed the light conversion efficiency of. In the case of a solar cell using an electrolyte solution containing an imidazolium salt of PMI or HMI including DMI which is the most widely used (Examples 1 to 3), the light conversion efficiency is 5.9 to 6.3%, and the electrolyte composition according to the present invention is already The increase in the light conversion efficiency of up to 20% was higher than that of the DMII, which had the highest light conversion efficiency among the solium salts. More specifically, the light conversion efficiency tended to decrease slightly as n1 or n2 decreased. The smaller the substituent was (the smaller the number of carbons), the larger the substituent was, the larger the R1 was, and the light conversion efficiency was increased.

In Comparative Examples 4 to 8, which used a mixture of imidazole salts according to the prior art, all showed a tendency to decrease the light conversion efficiency slightly compared to Comparative Examples 1 to 3, which were used alone, and also imidazolium according to the present invention. In the case of mixed use, the light conversion efficiency tended to decrease slightly. However, when the compound of Preparation Example 4 was mixed, the light conversion efficiency was greatly increased.

Table 5 shows the results of measuring the light conversion efficiency of the electrolyte composition using no organic solvent using the characteristics of the room temperature ionic liquid. As in Table 4, it can be seen that the composition which does not use a solvent is also greatly improved in light conversion efficiency compared to the comparative example.

More specifically, the electrolyte composition in which PMII or HMII, which is a room temperature ionic liquid according to the prior art, and the composition in which PMII and HMII were mixed showed light conversion efficiency of 3.2, 3.1, and 3.0%, respectively. In contrast, the electrolyte composition including a mixture of the preparation compounds of the present invention and DMII, PMII, or HMII exhibited an optical conversion efficiency of 3.4 to 4.7%. In particular, the smaller the n1 value, the more significant the effect of increasing the optical conversion efficiency. When n1 = 1, the optical conversion efficiency was 4.3-4.7%.

Claims (7)

Imidazolium salt represented by following formula (1).

[Formula 1]
Provided that R ₁ is an alkyl group of C1-C10 or Vinyl group; R ₂ is H or a C1-C3 alkyl group, n ₁ is an integer of 1 to 6; n ₂ is an integer of 1 to 3.
An electrolyte composition for dye-sensitized solar cells, comprising the imidazolium salt of claim 1 and iodine.
The method of claim 2,
The imidazolium salt is a dye-sensitized solar cell electrolyte composition, characterized in that the mixture with the compound of formula (2).

(2)
The method according to claim 2 or 3,
The iodine is a dye-sensitized solar cell electrolyte composition, characterized in that it contains 0.5 to 10% by weight of the imidazolium salt weight.
The method of claim 2,
Acetonitrile, 3-methoxy ppropionitrile, valeronitrile, ethylene carbonate, propylene carbonate, gamma-butylolactone Or N-methyl-2-pyrrolidone. An electrolyte composition for a dye-sensitized solar cell, further comprising an organic solvent.
The method of claim 5, wherein
The organic solvent is a dye-sensitized solar cell electrolyte composition, characterized in that less than 10 times the weight of the ammonium imidazolium salt.
The dye-sensitized solar cell manufactured using the electrolyte composition for dye-sensitized solar cell according to claim 2.