KR20160126274A - Solid Electrolyte for Dye-Sensitized Solar Cells Comprising 1,2-Bis(N-alkylimidazolium)ethane Diiodide and Manufacturing Method and Dye-Sensitized Solar Cells Including Thereof - Google Patents

Abstract

The present invention relates to a solid electrolyte used in a dye-sensitized solar cell to solve volatile and leakage problems of an existing liquid electrolyte, a manufacturing method thereof, and the dye-sensitized solar cell including the same. According to the present invention, a new solid electrolyte includes a 1, 2-bis (N-alkylimidazolium) ethane diiodide compound.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dye-sensitized solar cell solid electrolyte containing 1,2-bis (N-alkylimidazolium) ethane diazide, a method for producing the same, and a dye- 1,2-Bis (N-alkylimidazolium) ethane Diiodide and Manufacturing Method and Dye-Sensitized Solar Cells Including Thereof}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a solid electrolyte for fuel-responsive solar cells (DSSCs), and more particularly to a solid electrolyte for fuel- The present invention relates to a solid electrolyte comprising a bisimidazolium salt capable of replacing a liquid electrolyte, a method for producing the same, and a fuel-responsive solar cell including the same.

The development of solar cells at the level of a nature-friendly and sustainable future energy source has been studied continuously as a substitute for other fossil fuels. Among these, DSSCs can be applied to exterior window glass and glass greenhouse because they are less expensive than conventional silicon solar cells and can be composed of transparent electrodes. However, since the photoelectric conversion efficiency is generally low, Technology has limited practical application.

In the dye-sensitized solar cell, which was first reported in 1991, numerous inventions have been reported through the application of various dyes. A typical dye-sensitized solar cell is composed of a transparent electrode, a semiconductor layer metal oxide, a dye photosensitizer, an electrolyte, and an electrode. Specifically, a transparent conducting oxide electrode such as fluorinated tin oxide (FTO) or indium tinoxide (ITO) used as a substrate for both electrodes, a nonoparticulated oxide semi-conductor layer such as TiO ₂ and ZnO, a ruthenium Electrolytes containing dye-sensitizers, electrolytes and redox couples, such as inorganic or organic dyes, and metallic catalysts such as platinum, which act as counter electrodes.

However, existing liquid electrolytes have been pointed out as leakage of solvent due to the use of an organic solvent and long-term stability of the battery due to volatilization of the solvent at a high temperature. Solid electrolytes have been developed to solve the volatility and leakage problems of liquid electrolytes during long-term operation, and have been developed using salts consisting of nitrogen-based cations such as ammonium salts and iodine anions.

Ionic liquids (Ionic Liquids, ILs), which have an imidazolium structure in the nitrogen-based cationic materials, have been mainly used for the development of protophilic electrolytes. The ionic liquid is an ionic liquid, Liquids, RTILs) Due to their high electrical conductivity, negligible vapor pressure and high thermal stability, they are known to be suitable for semi-solid electrolytes. (W. Kubo, S. Kambe, S , Nakade, T. Kitamura, K. Hanabusa, Y. Wada, and S. Yanagida, J. Phys Chem B 2003, 107, 4374;.. W. Kubo, T. Kitamura , K. Hanabusa, Y. Wada, and S. Yanagida, Chem . Commun ., 2002 , 374; S. Seki, MABH Susan, T. Kaneko, H. Tokuda, A. Noda, and M. Watanabe, J. Phys . Chem. B 2005, 109, 3886)

In Korean Patent Registration No. 10-1247596, an organic-inorganic hybrid type polyethylene glycol-polyphthalic oligomeric silsesquioxane (PEG-POSS) nanoparticle was used as a solid electrolyte for a dye-sensitized solar cell. However, the material used is very expensive and difficult to commercialize, and the conductivity is still lower than 10 ^-4 S / cm. Korean Patent Laid-Open Publication No. 10-2014-0048368 discloses a quasi-solid electrolyte using cyclosiloxane tetraimidazolium salt and exhibits a light conversion efficiency of about 6 to 8%. However, for the synthesis of materials, expensive platinum catalysts are used and toxic organic substances such as SOCl 2 and pyridine are required to be used in large quantities, so that commercialization is also difficult. Korean Registered Patent No. 10-1150702 (registered number) shows a light conversion efficiency of up to 8.6% after preparing a semi-solid polymer electrolyte for a dye-sensitized solar cell. This quasi-solid polymer electrolyte uses a heteroarylalkyl compound having a cyclic structure, which is difficult to synthesize, as a co-adsorbent having hole conduction characteristics, and at the same time, it is easy to commercialize it as a ligand of Eu ^{3 +} or Tb ^{3 +} as a wavelength converting rare earth inorganic complex Or a very expensive synthetic compound dendrimer G1, G2 or G3 is used.

In the present invention, a solid electrolyte for dye-sensitized solar cells (DSSCs) using Organic Ionic Plastic Crystals (OIPCs) was developed. OIPCs materials exhibit phase-change properties in the crystalline phase when the temperature changes below the melting point. They are monomolecular crystalline materials, but exhibit high ionic conductivity with high hardness. The OIPCs materials based on bisimidazolium have been reported in the past literature. (M. Lee, UH Choi, S. Wi, C. Slebodnick, RH Colby and HW Gibson J. Mater . Chem. 2011 , 21 , 12280) , A solid electrolyte which does not use a polymer substance was prepared and a dye-sensitized solar cell was prepared using the solid electrolyte, thereby completing the present invention.

The present invention relates to a solid electrolyte capable of solving volatility and leakage problems of a liquid electrolyte used in a dye-sensitized solar cell and improving efficiency and long-term stability, a process for producing the same, and a dye- have.

In order to achieve the above object, the present invention provides 1,2-bis (N-alkylimidazolium) ethane diiodide, a novel OIPCs material, and a process for its preparation.

The present invention also provides a solid electrolyte for a dye-sensitized solar cell, which comprises 1,2-bis (N-alkylimidazolium) ethane diiodide OIPCs material.

The present invention relates to a solid electrolyte capable of solving volatility and leakage problems of a liquid electrolyte used in a dye-sensitized solar cell and improving efficiency and long-term stability, a process for producing the same, and a dye- have.

1 is a ¹ H NMR analysis result of 1,2-bis (N-octylimidazolium) ethane diiodide (500 MHz, CDCl ₃ , room temperature).
2 shows the results of DSC analysis of 1,2-bis (N-octylimidazolium) ethane diiodide (N ₂ , -50 to 230 ^° C, heating and cooling rate 10 K / min, Lt; / RTI > cooling).
3 shows the results of TGA analysis of 1,2-bis (N-octylimidazolium) ethane diiodide (N ₂ , room temperature to 500 ^° C, heating rate 10 K / min).

Hereinafter, the present invention will be described in detail.

The present invention provides a solid electrolyte for a dye-sensitized solar cell, which comprises novel 1,2-bis (N-alkylimidazolium) ethane diiodide OIPCs.

In the present invention, the 1,2-bis (N-alkylimidazolium) ethane diiodide OIPCs is represented by the following formula 1:

The present invention also provides a process for preparing 1,2-bis (N-alkylimidazolium) ethane diiodide.

In an embodiment of the present invention, the 1,2-bis (N-alkylimidazolium) ethane diiodide is chemically synthesized by the method shown in Reaction 1 and Reaction 2.

[Reaction Scheme 1]

[Reaction Scheme 2]

To explain more specifically, the present invention is 1,2-bis-alkyl, such as Scheme 1, through the reaction with the imidazole (alkylimidazole, 1) and 1,2-dibromoethane (1,2-dibromoethane, 2) ( N-alkylimidazolium) ethane bromide salt is prepared by an ion exchange reaction as shown in Reaction Scheme 2, and then 1,2-bis (N-alkylimidazolium) ) ethane diiodide, 3 ) can be synthesized.

In the above Reaction Scheme 1, alkylimidazole ( 1 ) is preferably an alkylimidazole having 1 to 20 carbon atoms and more preferably an alkylimidazole having 6 to 16 carbon atoms. Examples of the reaction solvent include deionized water, acetone, acetonitrile (CH ₃ CN), dimethylformamide (DMF), dimethylsulfoxide (DMSO), N-methylpyrrolidinone ), Methanol, ethanol, or isopropanol, and the solubility of the reactant may be considered. The most suitable solvent is any one selected from water (DI water), acetone, acetonitrile (CH ₃ CN), tetrahydrofuran (THF) or dimethylformamide (DMF). The reaction temperature is preferably 30 to 150 ^° C, more preferably 50 to 120 ^° C.

In the ion exchange reaction of step 2 of the above reaction scheme, lithium iodide, sodium iodide, potassium iodide, magnesium iodide, copper iodide, silicon iodide, manganese iodide, barium iodide, molybdenum iodide, calcium iodide, iron iodide, cesium iodide, Sodium iodide, ammonium iodide and the like, and more preferably one selected from sodium iodide, potassium iodide, cesium iodide and ammonium iodide. The solvent used in the ion exchange reaction of step (b) may include deionized water, acetone, acetonitrile (CH ₃ CN), dimethylformamide (DMF), dimethylsulfoxide (DMSO) N-methylpyrrolidinone (NMP), methanol, ethanol, isopropanol, 1-butanol, tert-butanol, ethyl acetate (EA), tetra Tetrahydrofuran (THF), or ethyl ether, and the solubility of each substance is taken into account.

However, the production method of the bisimidazolium diiodide compound according to the present invention is not particularly limited to the above method, and any method can be used as long as it is a conventional synthesis method.

The present invention also provides a solid electrolyte for a dye-sensitized solar cell comprising 1,2-bis (N-alkylimidazolium) ethane diiodide OIPCs material prepared by the above method.

In the present invention, the solid electrolyte can be used directly as a substitute for a liquid electrolyte or a quasi-solid electrolyte using a polymer used in a conventional dye-sensitized solar cell, and can be used as a substitute for a liquid electrolyte or a polymer due to leakage and volatilization In addition to solving the problem, it may be used with other non-ionic plastic crystals, ionic liquids or OIPCs materials, or with additional additives.

It is to be understood that the following examples are illustrative of the present invention and that various changes and modifications may be made therein without departing from the spirit and scope of the invention. It will be apparent to those skilled in the art that such variations and modifications fall within the scope of the appended claims.

Example 1 Preparation of 1,2-bis (N-octylimidazolium) ethane diiodide (bis (N-octylimidazolium) ethane diiodide)

1-octylimidazole (3.97 g, 22 mmol) and 1,2-dibromoethane (2.07 g, 11 mmol) were added to 20 mL of acetonitrile (MeCN) The solution is refluxed for 3 days and the mixture is then cooled at ambient temperature. After removal of the solvent, THF is added and the insoluble precipitate is filtered and rinsed 3 times with THF to obtain the bisimidazolium bromide salt. Then, the bromine salt was dissolved in distilled water (20 mL), NaI (5.0 g, 33 mmol) was added to the solution, and the mixture was stirred for 1 to 2 hours. The resulting precipitate was filtered, rinsed twice with distilled water and dried in an oven to obtain 1,2-bis (N-octylimidazolium) ethane diiodide (yield 80%).

≪ Example 2 > Preparation of electrolyte

Mix 10 parts of 1,2-bis (N-octylimidazolium) ethane diiodide, 90 parts of succinonitrile, and 1 part of I2, warm to ~ 80 ^° C and mix well. A solid electrolyte was prepared.

Example 3: Preparation of dye-sensitized solar cell

Titanium oxide was prepared by bar coating and heat treated at 450 ^° C for 30 minutes to prepare a photoelectrode composed of nanoparticles, followed by 12 hours of dye adsorption. In the case of the solid electrolyte, it was heated to the appropriate temperature below the boiling point, and when it was in a liquid state, it was injected into the device. A general platinum counter electrode was manufactured by a thermal decomposition process and the device was fabricated using the solid electrolyte developed in the present invention.

<Comparative Example>

TiO 2 was prepared by bar coating and heat treated at 450 ^° C for 30 minutes to prepare a photoelectrode composed of nanoparticles and then dye adsorption was carried out for 12 hours. A common platinum counter electrode was prepared by pyrolysis process using a liquid electrolyte using a liquid electrolyte containing 1-butyl-3-methyl-imidazolium iodide, LiI, I₂, guanidinium thiocyanate, 4-tert-butylpyridine, acetonitrile and valeronitrile Completion of device fabrication.

<Experimental Examples> Confirmation of physical properties of 1,2-bis (N-alkylimidazolium) ethane diiodide compound

The 1,2-bis (N-alkylimidazolium) ethane diiodide compound synthesized as in Example 1 can be confirmed by ¹ H NMR as shown in FIG. The 1,2-bis (N-octylimidazolium) ethane diiodide synthesized was dissolved in CDCl ₃ and analyzed by ¹ H NMR. Imidazolium hydrogens showed three single peaks at over 7 ppm, The ethylene structure connecting the zolmium showed a single peak at 5.6 ppm. The N-CH ₂ - of the octyl branch is shown as a triplet at 4.2 ppm, and the remaining peaks at 2 ppm or less originate from the later octyl branch.

As a result of measurement of thermal properties by differential scanning calorimetry as shown in FIG. 2, it was found that the thermal properties of 1,2-bis (N-octylimidazolium) ethane diiodide were changed from -50 ^° C to -18 ^° C , -8 ^° C, and 18 ^° C, respectively. The highest endothermic peaks were observed at 51 ^° C below the melting point. Each endothermic peak means a change in solid phase to a new solid phase, which means that an endothermic process is required.

As shown in FIG. 3, thermal stability test results by TGA analysis. The 5% weight reduced temperature was found to be 267 ^o C, and thus it was found to be stable over a long period of time under typical dye-sensitized solar cell operating conditions of 250 ^o C or lower.

INDUSTRIAL APPLICABILITY The present invention is industrially applicable because it is possible to produce a solid electrolyte and a dye-sensitized solar cell which can solve the volatility and leakage problem of the liquid electrolyte and improve the efficiency and the long-term stability.

Claims (9)

An imidazolium compound represented by the following formula (1):
[Chemical Formula 1]

The method according to claim 1,
The imidazolium compound includes an iodide ion (I-), which is an inorganic anion, based on 1,2-bis (N-alkylimidazolium) ethane diiodide, and has an R structure (Organic Ionic Plastic Crystals (OIPCs)) material in which the solid-solid phase change temperature is changed by substituting different kinds of carbon atoms. (1) obtaining an imidazolium bromide salt as shown in Formula (1) through reaction of an alkylimidazole with dibromoalkane; And
(2) dissolving a bromine salt in a solvent and subjecting it to an ion exchange reaction with an iodide compound to obtain a bisimidazolium diiodide as shown in Chemical Formula 2. The method of claim 3,
Wherein the alkyl group of the alkylimidazole used in the step (1) has 1 to 20 carbon atoms. The method of claim 3,
In step (1), distilled water, acetone, acetonitrile (CH ₃ CN), dimethylformamide (DMF), dimethylsulfoxide (DMSO), 1-methylpyrrolidinone (NMP), methanol, ethanol or isopropanol Wherein the method comprises the steps of: The method of claim 3,
(2) above lithium iodide (LiI) in iodide compound in step, sodium iodide (NaI), potassium iodide (KI), magnesium iodide (MgI _2), copper iodide (CuI ₂₎ iodide, silicon (SiI _4), iodide, manganese (MnI _2), barium iodide (BaI _2), iodide, molybdenum (MoI _3), calcium iodide (CaI _2), iodide, iron (FeI _3), iodide, cesium (CsI), zinc iodide (ZnI ₂₎ or ammonium iodide (NH ₄ I) is used as an ion exchange reagent. An electrolyte for a dye-sensitized solar cell comprising the 1,2-bis (N-alkylimidazolium) ethane diazide compound of claim 1. 8. The method of claim 7,
Wherein the electrolyte is a gel type or a solid at room temperature. 8. The method of claim 7,
Wherein the quasi-solid or solid electrolyte is prepared by adding iodine (I ₂ ) and succiconitrile to 1,2-bis (N-alkylimidazolium) ethane diiodide. Electrolyte

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