WO2009082163A2

WO2009082163A2 - Novel ru-type sensitizers and method of preparing the same

Info

Publication number: WO2009082163A2
Application number: PCT/KR2008/007631
Authority: WO
Inventors: Ho-Gi Bae; Chong-Chan Lee; Jong-Hyub Baek; Hoe-Taek Yang
Original assignee: Dongjin Semichem Co Ltd
Current assignee: Dongjin Semichem Co Ltd
Priority date: 2007-12-26
Filing date: 2008-12-24
Publication date: 2009-07-02
Anticipated expiration: 2010-06-26
Also published as: WO2009082163A3; TW200938594A; CN101910322A; KR20090071426A; JP2011510107A

Abstract

The present invention relates to novel Ru-type dye and a method for preparing the same, more specifically to dye which is be used for a dye-sensitized solar cell to show remarkably improved photoelectric transformation efficiency compared to the existing dye, strengthens bonding force with titanium dioxide, and has excellent Jsc(short circuit photocurrent density) and molar absorption coefficient, thus largely improving the efficiency of solar cell, and a method for preparing the same.

Description

NOVEL Ru-TYPE SENSITIZERS AND METHOD OF PREPARING THE SAME

[Technical Field]

The present invention relates to a novel Ru-type dye used for a dye-sensitized solar cell and a method of preparing the same.

[Background Art]

Since a dye-sensitized nanoparticle titanium oxide solar cell was developed by Michael Gratzel et al. of Swiss Federal Institute of Technology Lausanne(EPFL) at the year of 1991, many studies regarding this are under progress. Because the dye- sensitized solar cell has remarkably low manufacture cost compared to the existing silicon solar cell, it can replace the existing amorphous silicon solar cell. And, the dye- sensitized solar cell is mainly comprised of dye molecules capable of absorbing visible rays to generate electron-hole pair, and transition metal oxide for transmitting the generated electrons.

Representative dyes used for dye-sensitized solar cell of the prior art include the compounds shown below.

However, it is still required to increase bonding force with oxide semiconductor particles, photoelectric transformation efficiency, Jsc(short circuit photocurrent density) and molar absorption coefficient so as to further improve efficiency and durability of a solar cell. Therefore, there is a demand for the development of novel dyes.

[Disclosure] [Technical Problem] In order to solve the above problems of the prior art, it is an object of the present invention to provide dye which shows remarkably improved photoelectric transformation efficiency compared to dyes of the prior art, strengthens bonding force with oxide semiconductor particles, and has excellent Jsc(short circuit photocurrent density) and molar absorption coefficient, thus greatly improving efficiency of a solar cell, and a method of preparing the same.

It is another object of the present invention to provide a dye-sensitized photoelectric transformation element comprising the above explained dye, thus showing remarkably improved photoelectric transformation efficiency, having strengthened bonding force with oxide semiconductor particles, and having excellent Jsc(short circuit photocurrent density) and molar absorption coefficient, and, a solar cell with greatly improved efficiency.

[Technical Solution]

In order to achieve the objects, the present invention provides Ru -type dye represented by the following Chemical Formula 1 : [Chemical Formula 1]

(wherein al ring is optionally substituted by one or more substituent selected from the group consisting of halogen atom, amide, cyano, hydroxyl, nitro, acyl, Ci_-30 alkyl and C_1- ₃₀ alkoxy group; and

X and Y are independently methyl or a represented by one of the following Chemical Formulas 2-1 to 2-14, and at least one of X and Y is represented by one of the following Chemical Formulas 2-1 to 2-14:

(wherein (*) represents a bond, bl ring is optionally substituted by one or more substituent selected from the group consisting of halogen atom, amide, cyano, hydroxyl, nitro, acyl, C_1-3O alkyl and Ci_-30 alkoxy group; A is independently S or O; and, R, R₁, R₂ and R₃ are independently hydrogen, Ci_-J5 alkyl, Ci_-I5 alkoxy, C_6-20 aryl or C_6-20 heteroaryl; and, n is an integer of from 1 to 10).

The present invention also provides a method of for preparing a dye represented by the following Chemical Formula 1, which comprises the step of reacting a compound of the following Chemical Formula 3 with compounds of the following Chemical Formula 4, Chemical Formula 5, and Chemical Formula 6 in order:

[Chemical Formula 4]

[RuCl₂(/?-cymene)]₂

[Chemical Formula 6]

NH₄NCS

(wherein X, Y and al are as defined above). The present invention also provides a dye-sensitized photoelectric transformation element comprising oxide semiconductor particles, wherein the compound represented by the above Chemical Formula 1 is supported on the oxide semiconductor particles.

The present invention also provides a dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element.

[Advantageous Effects]

The novel Ru-type dye of the present invention shows remarkably improved photoelectric transformation efficiency compared to dyes of the prior art, strengthens bonding force with oxide semiconductor particles, and has excellent Jsc(short circuit photocurrent density) and molar absorption coefficient, thus greatly improving the efficiency of solar cell.

[Brief Description of Drawings] Fig. 1 is an absorption graph using DCSC 1, DCSC 2, DCSC 3, DCSC 4, DCSC

8, DCSC 9 according to the embodiments of the present invention and N719 according to comparative example as dye.

[Mode for Invention] The present invention will now be explained in detail.

The present inventors have discovered that if a compound represented by the Chemical Formula 1 is supported on oxide semiconductor particles to prepare a dye- sensitized solar cell, the compound strongly bonds to the oxide semiconductor particles, thus the solar cell shows excellent durability, and it has excellent Jsc(short circuit photocurrent density) and molar absorption coefficient, thus the dye-sensitized solar cell shows excellent efficiency compared to the existing ones, and completed the present invention. The Ru-type dye of the present invention is represented by the following Chemical Formula 1 :

(wherein al ring is optionally substituted by one or more substituent selected from the group consisting of halogen atom, amide, cyano, hydroxyl, nitro, acyl, Ci_-30 alkyl and C_1- ₃o alkoxy group; and

[Chemical Formula 2-1]

(wherein (*) represents a bond, bl ring is optionally substituted by one or more substituent selected from the group consisting of halogen atom, amide, cyano, hydroxyl, nitro, acyl, Ci_-30 alkyl and Ci_-3O alkoxy group; A is independently S or O; and, R, Ri, R₂ and R₃ are independently hydrogen, C_1-I₅ alkyl, C_M5 alkoxy, C_6-20 aryl or C_6-20 heteroaryl; and, n is n integer of from 1 to 10).

More preferably, it is represented by one of the following Chemical Formulas 1-1 to 1-38:



(wherein A and R are as defined in the Chemical Formula 1).

The present invention also provides a method of preparing the dye represented by the above Chemical Formula 1 , which comprises the step of reacting a compound of the following Chemical Formula 3 with compounds of the following Chemical Formula 4, Chemical Formula 5, and Chemical Formula 6 in order:

[Chemical Formula 4] [RuCl₂(p-cymene)]₂

[Chemical Formula 5]

(wherein X, Y and al are as defined above).

Preferably, the dye of the present invention is prepared by the process represented by one of the following Reaction Formulas 1 to 6:

(in the Reaction Formula 4, R is independently hydrogen, C_1-I5 alkyl, Ci_-15 alkoxy, C_6-20 aryl or C_6-20 heteroaryl)



In the above Reaction Formulas, the compounds used for starting material in the preparation of the dye of the Chemical Formula 1 can be prepared by common method or purchased. Specifically, dithienothiophene, trithienothiophene and tetrathienothiophene can be prepared by the following Preparation Formulas 1-3. And, dithienothiophene can be prepared with relatively short reaction time, and it can be recrystallized without column purification, thus its synthesis is very simple (See [Chem. Mater. 2007, 19, 4007- 4015] and [J. Mater. Chem. 1999, 9, 1719-1725]).

The present invention also provides a dye-sensitized photoelectric transformation element, wherein the dye represented by the above Chemical Formula 1 is supported on oxide semiconductor particles. The dye-sensitized photoelectric transformation element of the present invention can be prepared by any method for preparing a dye-sensitized photoelectric transformation element for solar cell using dyes of the prior art. Preferably, oxide semiconductor thin film is formed on a substrate using oxide semiconductor particles, and the dye of the present invention is supported thereon.

The substrate on which oxide semiconductor thin film is formed is preferably conductive, and is available on the market. For example, those prepared by forming a conductive metal oxide film such as indium, fluorine, antimony doped tin oxide, etc. or metal film such as steel, silver, gold, etc. on the surface of glass or on the surface of transparent polymer such as polyethyleneterephthalate or polyethersulfone, etc. can be used. Preferably, it has conductivity of 1000Ω or less, more preferably 100Ω or less. As the oxide semiconductor particles, metal oxide is preferable. For examples, titanium, tin, zinc, tungsten, zirconium, gallium, indium, yttrium, niobium, tantalum, vanadium oxide, etc can be used. Preferably, titanium, tin, zinc, niobium, or indium oxide is used, titanium oxide, zinc oxide or tin oxide is more preferable, and titanium oxide is most preferable. The oxide semiconductor can be used alone or in combination, or it can be coated on the surface of semiconductor. The oxide semiconductor particles preferably have the average diameter of 1 ~ 500 nm, more preferably 1 - 100 nm. And, those having large diameter and those having small diameter can be mixed, or they can be used in multi-layers.

The oxide semiconductor thin film can be prepared by spraying oxide semiconductor particles to form a thin film thereof directly on a substrate; electrically depositing semiconductor particle thin film using a substrate as an electrode; or, applying semiconductor particle slurry or paste containing particles obtained by hydrolysis of semiconductor particle precursor such as semiconductor alkoxide, etc. on a substrate, and drying, curing or sintering. Preferably, paste is applied on a substrate, and in this case, slurry can be obtained by dispersing secondary coagulated oxide semiconductor particles in a dispersion medium to a first particle diameter of 1 - 200 nm by common method.

As the dispersion medium, those capable of dispersing semiconductor particles can be used without limitation. For examples, water, alcohol such as ethanol, ketone such as acetone, acetylaetone, or hydrocarbon such as hexane can be used, and they can be used in combination. Water is preferable because it minimizes change of viscosity of slurry. And, a dispersion stabilizer can be used in order to stabilize the dispersion of the oxide semiconductor particles. As the dispersion stabilizer, acid such as acetic acid, hydrochloric acid, nitric acid, etc., or acetylacetone, acrylic acid, polyethyleneglycol, polyvinylalcohol, etc. can be used.

The substrate on which slurry is applied can be sintered, and the sintering temperature is 100^°C or more, preferably 200 "C or more, and the upper limit of the sintering temperature is melting point(softening point) of the substrate, commonly 900 °C, preferably 600 "C . The sintering time is not specifically limited, but preferably within 4 hours. The thickness of the thin film on the substrate is 1 - 200 μm, preferably 1 - 50 μm- In case sintering is conducted, oxide semiconductor particle thin layer is partly welded, but such welding does not cause any damages in the present invention.

And, the oxide semiconductor thin film can be subjected to a secondary treatment. For example, the thin film can be immersed in a solution of alkoxide, chloride, nitride, sulfide, etc. of the metal identical to the semiconductor, and dried or re-sintered, thereby improving the property of the thin film. As the metal alkoxide, titanium ethoxide, titanium isoproepoxide, titanium t-butoxide, n-dibutyl-diacetyl tin, etc. can be used, and the alcohol solution thereof can be used. As the chloride, titanium tetrachloride, tin tetrachloride, zinc chloride, etc. can be used, and the aqueous solution thereof can be used.

Thus obtained oxide semiconductor thin film is comprised of oxide semiconductor particles.

The method for supporting dye on oxide semiconductor particles in the form of a thin film is not specifically limited, and for example, a substrate having the oxide semiconductor thin film formed thereon can be immersed in a solution obtained by dissolving the dye represented by the above Chemical Formula 1 in a solvent capable of dissolving the same, or in a dispersion obtained by dispersing the dye. The concentration of the solution or dispersion can be appropriately determined. Immersion temperature is from room temperature to boiling point of the solvent, and immersion time is about 1 minute to 48 hours. As the solvent used for dissolving the dye, methanol, ethanol, acetonitrile, dimethylsulfoxide, dimethylformamide, acetone, t-butanol, etc. can be used. The concentration of the solution is commonly 1 x 10^"6 M to IM, preferably 1 x 10^"5 M to 1 x 10^"1 M. Thus, a dye-sensitized photoelectric transformation element comprising oxide semiconductor particles in the form of thin film can be obtained.

One kind of the dye represented by the Chemical Formula 1 can be used or several kinds of dyes can be used in combination. In case several kinds of dyes are used in combination, only dyes according to the present invention can be used, or the dyes according to the present invention can be mixed with other dyes or metal complex dyes. As the metal complex dyes that can be mixed, although not specifically limited, ruthenium complex or quaternary salt thereof, phthalocyanin, porphyrin, etc. which are described in M.K.Nazeeruddin, A.Kay, I.Rodicio, R.Humphry-Baker, E.Muller, P.Liska, N.Vlachopoulos, M.Gratzel, J. Am. Chem. Soc, Vol.115, p 6382(1993) are preferable. As the organic dye that can be mixed, metal-free phthalocyanin, porphyrin, cyanin, merocyanin, oxonol, or triphenylmethane dye, methyne dye such as acrylate dye described in WO2002/011213, xanthenes, azo, anthraquinone, perylene dye can be used. In case two or more kinds of dyes are used in combination, they can be sequentially absorbed in semiconductor thin layer, or mixed, dissolved and absorbed.

When the dye is supported on the oxide semiconductor particle thin film, in order to prevent bonding between dyes, it is preferable to support dye in the presence of an inclusion compound. As the inclusion compound, cholic acid such as deoxycholic acid, dehydrodeoxycholic acid, kenodeoxycholic acid, cholic acid methyl ester, cholic acid sodium, etc., steroid compounds such as cholic acid, polyethyleneoxide, etc., crown ether, cyclodextrin, calyxarene, polyethyleneoxide, etc. can be used.

After the dye is supported, the surface of semiconductor electrode can be treated with amine compound such as 4-t-butyl pyridine, or compound having acid group such as acetic acid, propionic acid, etc. For example, a substrate having dye-supported semiconductor particle thin film formed thereon can be immersed in an ethanol solution of amine.

The present invention also provides a dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element. It can be prepared by common method of preparing a solar cell using photoelectric transformation element of the prior art. The dye-sensitized solar cell may be comprised of photoelectric transformation element electrode (negative electrode) wherein the dye represented by the Chemical Formula 1 is supported on the oxide semiconductor particles, counter electrode(positive electrode), redox electrolyte, hole-transport material or p-type semiconductor, etc.

Preferably, the dye-sensitized solar cell of the present invention is prepared by coating titanium oxide paste on a transparent conductive substrate; sintering the coated substrate to form a titanium oxide thin film; immersing the substrate having titanium oxide thin film formed thereon in a mixed solution in which the dye represented by the Chemical Formula 1 is dissolved, so as to form a dye-absorbed titanium oxide film electrode; providing a second glass substrate having a counter electrode formed thereon; forming a hole penetrating the second glass substrate and the counter electrode; placing thermoplastic polymer film between the counter electrode and the dye-absorbed titanium oxide film electrode and heat-pressing them to join the counter electrode and the titanium oxide film electrode; injecting electrolyte into the thermoplastic polymer film placed between the counter electrode and the titanium oxide film electrode through the hole; and, sealing the thermoplastic polymer. The redox electrolyte, hole-transport material, or p-type semiconductor may be liquid, coagulated form(gel and gel phase), solid, etc. The liquid includes those obtained by dissolving redox electrolyte, dissolved salt, hole-transport material, or p-type semiconductor in a solvent, and a room temperature dissolved salt. The coagulated form(gel and gel phase) includes those obtained by including redox electrolyte, dissolved salt, hole-transport material, or p-type semiconductor in a polymer matrix or low molecular gellant, etc. The solid includes redox electrolyte, dissolved salt, hole- transport material, or p-type semiconductor.

As the hole-transport material, amine derivatives, or conductive polymer such as polyacetylene, polyaniline, polythiophene, etc., or those using discotic liquid crystal phase such as triphenylene can be used. As the p-type semiconductor, CuI, CuSCN, etc. can be used. As the counter electrode, those having conductivity and catalytic function on reduction of redox electrolyte are preferable, and, for example, those obtained by depositing platinum, carbon, rhodium, ruthenium, etc. on a glass or polymer film, or applying conductive particles thereon can be used.

As the redox electrolyte for used in the solar cell of the present invention, halogen redox electrolyte consisting of halogen compound comprising halogen ion as a counter ion and a halogen molecule, metal redox electrolyte such as ferrocyanide- ferrocyanide or ferrocene-ferricynium ion, metal complex such as cobalt complex, etc., organic redox electrolyte such as alkylthio-alkyldisulfide, viologen dye, hydroquinone- quinone, etc. can be used, and halogen redox electrolyte is preferable. As the halogen molecule comprised in the halogen redox electrolyte, iodine molecule is preferable. As the halogen compounds comprising halogen ion as counter ion, halogenated metal salt such as LiI, NaI, KI, CaI₂, MgI₂, CuI, etc., or organic ammonium salt of halogen such as tetraalkylammonium iodide, imidazolium iodide, pyridium iodide, etc. or I₂ can be used.

In case the redox electrolyte is in the form of a solution comprising the same, an electrochemically inert solvent can be used. For example, acetonitrile, propylenecarbonate, etylenecarbonate, 3-methoxypropionitrile, methoxyacetonitrile, ethyleneglycol, propyleneglycol, diethyleneglycol, triethyleneglycol, butyrolactone, dimethoxyethane, dimethylcarbonate, 1,3-dioxolane, methyl formate, 2- methyltetrahydrofurane, 3-methoxy-oxazolidin-2-on, sulforane, tetrahydrofurane, water, etc. can be used, and acetonitrile, propylenecarbonate, ethylenecarbonate, 3- methoxypropionitrile, ethyleglycol, 3-methoxy-oxazolidin-2-on, or butyrolactone is preferable. These solvent can be used alone or in combination. As a gel phase positive electrolyte, those obtained by including electrolyte or electrolyte solution in oligomer or polymer matrix, or including electrolyte or electrolyte solution in a starch gellant can be used. The concentration of the redox electrolyte is preferably 0.01 - 99 wt%, and more preferably 0.1 - 30 wt%.

The solar cell of the present invention can be obtained by arranging a photoelectric transformation element(negative electrode) wherein dye is supported on oxide semiconductor particles on a substrate and a counter electrode(positive electrode) opposite each other, and filling redox electrolyte containing solution therebetween.

The present invention will be explained with reference to the following examples, however, these are only to illustrate the present invention and the scope of the present invention is not limited thereto.

[Example]

Example 1: Synthesis of dye

The Ru-type dye of the present invention, DCSC l(Chemical Formula 1-1) and

DCSC(Chemical Formula 1-2) were synthesized by the reaction as shown in the above Reaction Formula 1. All the reactions were conducted under argon gas, and the used solvent was distilled with sodium. As starting material, Aldrich and Strem reagents were used without purification.

(1) Preparation of compound (1)

Cyano-acetic acid benzyl ester (8.4 g, 47.95 mmol) and ammonium acetate (0.709 g, 9.2 mmol) were dissolved in 25 mL of cyclohexane, and acetic acid (2.5 g,

41.75 mmol) was slowly added thereto dropwise. The reaction mixture was agitated for

15 minutes, and then 5-methyl-thiophene-2-carbaldehyde (6.05 g, 47.95 mmol) was added thereto, and the reaction mixture was agitated under nitrogen gas at 110°C for 5 hours. After the agitation, ammonium acetate (0.709 g, 9.2 mmol) was added at room temperature and the reaction mixture was agitated at 110^°C for 12 hours. Then, an organic layer was extracted with 200 mL of ethylene acetate and water, and separated by recrystallization under ethylene acetate.

(2) Preparation of compound (2) Compound (2) was prepared by the same process as the compound (1), except that the same mmol of cyano-acetic acid octyl ester was used instead of cyano-acetic acid benzyl ester.

(3) Preparation of compound (3)

The compound (1) (5 g, 17.6 mmol) and NBS (3.5 g, 19.41 mmol) were dissolved in 150 mL of CCl₄, and then AIBN (0.145 g, 0.088 mmol) was added thereto, and the reaction mixture was agitated under nitrogen gas at 80 "C for 12 hours. Then, the reaction mixture was filtered using a filter paper, and the solvent is dried, and then, an organic substances were extracted with methylene chloride/H₂O using a separatory funnel, and the column was purified (eluent. EA : Hx = 1 : 10). To the separated compound (2.4 g, 6.61 mmol), 5 mL Of P(OEt)₃ was added, and the reaction mixture was agitated under nitrogen gas at 80 "C for 12 hours. After the agitation, starting material was removed with 250 mL of hexane and the column was purified (eluent. MC : Aectone = 1 : 1).

(4) Preparation of compound (4)

Compound (4) was prepared by the same process as the compound (3), except that the compound (2) was used instead of the compound (1).

(5) Preparation of compound (6)

To a compound (5) (0.13 g, 0.7 mmol) and KtOBu (0.2 g, 1.8 mmol), THF 20 mL was added, and the compound (3) (0.75 g, 1.8 mmol) was dissolved in 20 mL of THF and slowly added dropwise, and then the reaction mixture was agitated at 70 ^°C for 12 hours. After the reaction, the solvent was removed and an organic layer was extracted with MC and separated by recrystallization.

(6) Preparation of compound (7)

Compound (7) was prepared by the same process as the compound (6), except that the compound (4) was used instead of the compound (3).

(7) Synthesis of dye DCSCl, DCSC 2 Using the prepared compounds 6 and 7, DCSC l(Chemical Formula 1-1) and DCSC 2(Chemical Formula 1-2) were synthesized according to the Reaction Formula 1 by the synthesis method described in Chem. Mater. 2006, 18, 5604-5608.

Example 2: Synthesis of dye DCSC 3(Chemical Formula 1-3) and DCSC 4(Chemical Formula 1-4)

DCSC3 and DCSC 4 were synthesized according to the Reaction Formulas 2-1 by the synthesis method described in Chem. Mater. 2006, 18, 5604-5608, using compound 11 and compound 12 or 13(compound 13 for DCSC 3, compound 12 for DCSC 4).

Example 3: Synthesis of dye DCSC 9(Compound 1-7)

DCSC 9 was synthesized according to the Reaction Formula 3.

(1) Preparation of compound (16)

Compound (4) (0.3 g, 1.44 mmol) and CNCH₂COOH (0.27 g, 3.2 mmol) were dissolved in 25 mL of CH₃CN, and piperidine (0.05 mL, 0.5 mmol) was added thereto dropwise, and then, the reaction mixture was refluxed for 5 hours. After the reaction was completed, the compound was separated by washing three times each using 10 mL of CH₃CN lO mL.

(2) Preparation of dye DCSC 9

Dye DCSC 9 was synthesized using the compound 16 by the synthesis method described in Chem. Mater. 2006, 18, 5604-5608.

Example 4: Synthesis of dye compound 1-14(1)

Dye compound 1-14(1) was synthesized according to the following Reaction Formula 4-1. [Reaction Formula 4-1]

(1) Preparation of 5-(diethylamino)thiophene-2-carbaldehyde 5-bromothiophene-2-carbaldehyde (1 ml, 8.41 mmol), dietylamine (2.6 ml, 25.2 mmol) and TsOH (0.048 g, 0.25 mmol) were introduced in a reactor, and the reaction mixture was agitated under nitrogen gas with heating for 24 hours.

After the agitation, an organic layer was extracted with methylenechloride and water, and evaporated, and then purified by column (eluent. E.A : Hx = 1 : 2).

IH NMR(CDCl₃) : [ppm] = 0.89(m, 6H), 3.24(m, 4H), 6.7 (d, 3JHH - 2.4Hz, IH), 7.1 l(d, 3JHH = 2.4Hz, IH), 9.62.(s, IH).

(2) Preparation of 5,5'-(lE,l'E)-3,3'-(2,2'-bipyridine-4,4'-diyl) bis(prop-l-ene-3,l- diyl)bis(N,N-dieth ylthiophen-2-amine)

5-(diethylamino)thiophene-2-carbaldehyde (0.44 g, 2.38 mmol), tetraethyl 2,2'- bipyridine-4,4'-diylbis(methylene)diphosphonate (0.49 g, 1.13 mmol), and NaH (0.1 g, 2.48 mmol) were dissolved in 30 mL of THF, and then the reaction mixture was agitated under nitrogen gas with refluxing for 4 hours.

After the agitation, an organic layer was extracted with methylenechloride and water, and evaporated, and then, purified by column (eluent. E.A ). IH NMR(CDCl₃) : [ppm] = 0.89(m, 12H), 3.24(m, 8H), 6.26(d, 3JHH = 15.4Hz, 2H), ), 6.41(d, 3JHH = 15.4Hz, 2H), 6.7 (d, 3JHH = 2.4Hz, 2H), 7.01(d, 3JHH = 2.4Hz, 2H), 7.3 l(d, 3JHH= 5.4Hz, 2H), 8.01(s, 2H), 8.3 l(d, 3JHH - 5.4Hz, 2H).

(3) Preparation of compound 1-14(1)

Compound 1-14(1) was synthesized by the synthesis method described in Chem. Mater. 2006, 18, 5604-5608.

5,5'-(lE,l'E)-3,3'-(2,2'-bipyridine-4,4^l-diyl)bis(prop-l-ene-3,l-diyl)bis(N,N- diethylthiophen-2-amine) (0.26 g, 0.5 mmol),[Ru(p-Cymene)Cl₂]₂, (0.15 g, 0.25 mmol) 2,2'-bipyridine-4,4'-dicarboxylic acid (0.12 g, 0.5 mmol), NH₄NCS (0.19 g, 2.5 mmol).

Example 5: Synthesis of dye compound 1-14(2)

Dye compound 1-14(2) was prepared by the same process as in example 3, except the reaction is according to the Reaction Formula 4(in the Reaction Formula 4, R is hexyl).

Example 6: Synthesis of dye compound 1-15

Dye compound 1-15 was prepared according to the Reaction Formula 5 using dithienothiophene prepared by the Preparation Formula 1. (1) The synthesized 2-hexyldithieno[2',3']thiophene (10 g, 35.65 mmol) was dissolved in THF (50 ml), and n-BuLi 2 M (21 ml)was slowly added thereto dropwise at - 78 ⁰C , and then the reaction mixture was agitated at low temperature for 1 hour. Then, trimethyltin chloride IM (38 ml) was slowly added thereto dropwise at -78 °C, and the reaction mixture was agitated at low temperature for 1 hour and additionally at 0^°C for 30 minutes. After the agitation, an organic layer was extracted with methylenechloride and water, evaporated, and dried.

IH NMR(CDCl₃) : [ppm] = 0.4(s, 9H), 0.88(m, 3H), 1.29(m, 4H), 1.96(m, 4H), 2.55(m, 2H), 6.62(s, IH), 6.98(s, IH). (2) 2-trimethyl(4-hexyldithieno[2',3']thiophene-2-yl)stannane (0.6 g 1.34 mmol),

4,4'-dibromo-2,2'-bipyridine (0.35 g, 1.12 mmol), and Pd(PPh₃)4 (0.065 g, 0.056 mmol) were dissolved in THF (40 ml), and the reaction mixture was refluxed under nitrogen gas for 8 hours. Then, an organic layer as extracted with methylenechloride and water, and evaporated, and then purified by column.

(eluent. EA : Hx = 1 : 2) IH NMR(CDCl₃) : [ppm] = 0.88(m, 6H), 1.29(m, 8H), 1.96(m, 8H), 2.55(m, 4H), 6.70(s, 2H), 6.98(s, 2H), 7.34(d, 3JHH = 8.8Hz, 2H), 8.18(s, 2H), 8.42(d, 3JHH = 8.8Hz, 2H)

(3) The synthesized compound (0.8 g, 1.12 mmol) and [RuCl₂(p-Cymene)]₂ (0.34 g, 0.56 mmol) were dissolved in DMF(15 ml), and the reaction mixture was refluxed at 80 °C for 4 hours with blocking light. Then, 2,2'-bipyridine-4,4'-dicarboxylic acid (0.27 g, 1.12 mmol) was added, and the reaction mixture was refluxed again at 160 ^°C for 4 hours. NH₄NCS (0.85 g, 11.2 mmol) was added thereto, and the reaction mixture was refluxed again at 130 ^°C for 4 hours. After the reaction was completed, the reaction mixture was dried by vacuum distillation, washed with water and ether, and then filtered to remove the precipitate. The precipitate was dissolved in MeOH to which appropriate TBAOH was added, and subjected to sephadex purification (eluent. MeOH), and then, precipitated with nitrogen and filtered. Remained precipitate was washed with water and ether, and dried.

IH NMR(CDCl₃) : [ppm] = 0.88(m, 6H), 1.29(m, 8H), 1.96(m, 8H), 2.55(m, 4H), 6.70(s, 2H), 6.98(s, 2H), 7.34(m, 4H), 8.2 l(m, 4H), 8.44(m, 4H), 11.4(s, 2H).

Example 7: Synthesis of dye compound 1-16

Dye compound 1-16 was prepared according to the Reaction Formula 6 using diethienothiophene prepared according to the Preparation Formula 1. (1) Preparation of 2-hexyldithieno[2',3']thiophene As in the Example 4, dithieno[2',3']thiophene (0.37 g, 1.88 mmol) was dissolved in 30 mL of THF, and n-BuLi (1 ml, 2 mmol) was slowly added thereto dropwise at - 78 ^°C, and then, the reaction mixture was agitated for 1 hour. After the agitation, 1- bromohexane (0.28 ml, 2 mmol) was added at -78 "C, and the reaction mixture was agitated again for 1 hour. After the agitation, an organic layer was extracted with methylenechloride and water, and evaporated, and then purified by column.

(eluent. M.C : Hx = 1 : 2) IH NMR(CDCl₃) : [ppm] = 0.89(m, 3H), 1.24(m, 6H), 1.88(m, 2H), 3.24(m, 2H), 6.8 (m, 2H), 7.11(d, 3JHH = 2.4Hz, IH).

(2) Preparation of 2-hexyldithieno[2',3']thiophene-5-carboaldehyde

2-hexyldithieno[2',3']thiophene (0.3 g, 1.06 mmol) was dissolved in DMF(IO ml), and POC1₃(0.098 ml, 1.06 mmol) was added thereto dropwise, and then the reaction mixture was agitated under nitrogen gas at 80 "C for 4 hours. After the agitation, an organic layer was extracted with methylenechloride and water, evaporated, and purified by column (eluent.E.A : Hx = 1 : 2)

IH NMR(CDCl₃) : [ppm] = 0.89(m, 3H), 1.24(m, 6H), 1.88(m, 2H), 3.24(m, 2H), 6.9 (s, lH), 7.41(s, IH) 9.61 (s, IH).

(3) Preparation of 5,5'-(lE,lΕ)-3,3'-(2,2'-bipyridine-4,4'-diyl) bis(prop-l-ene-3,l- diyl) bis(2-hexy ldithieno[2',3']thiophene)

2-hexyldithieno[2',3']thiophene-5-carboaldehyde (0.3 g, 0.97 mmol), tetraethyl 2,2'-bipyridine-4,4'-diylbis(methylene)diphosphonate (0.22 g, 0.486 mmol), and NaH (0.5 g, 1.2 mmol) were dissolved in THF(30 ml), and the reaction mixture was agitated under nitrogen gas with refluxing for 4 hours. After the agitation, an organic layer was extracted with methylenechloride and water, and evaporated, and the purified by column(eluent. E.A )

IH NMR(CDCl₃) : [ppm] = 0.89(m, 6H), 1.24(m, 12H), 1.88(m, 4H), 3.24(m, 4H),, 6.64(s, 2H), ), 6.88(d, 3JHH = 15.4Hz, 2H), 7.1(s, 2H), 7.29(d, 3JHH = 15.4Hz, 2H), 7.3 l(d, 3JHH = 5.4Hz, 2H), 8.0 l(s, 2H), 8.3 l(d, 3JHH= 5.4Hz, 2H). (4) Preparation of compound 1-16

Compound 1-16 was prepared by the same process as the synthesis of 1-14(1) in the Example 4.

Example 8: Preparation of dye-sensitized solar cell

A solar cell was prepared using a TiO₂ film prepared from Dyesol titania paste(Dyesol Ltd., Australia). The Dyesol paste was coated on an FTO glass substrate which was pretreated with titanium(IV) isopropoxide by doctor blade method. The paste on FTO was sintered at 450 "C for 30 minutes to form a TiO₂ thin film layer with a thickness of 13 μm. The sintered thin film layer was immersed in a dye solution wherein DCSC 1 (Chemical Formula 1-1) prepared in the Example 1 is dissolved in DMF with a concentration of 0.5 mM at room temperature for 24 hours. The dye coated thin film was immersed in DMF solution for 3 hours in order to remove non-bonded dye, and then, immersed in ethanol solution for 3 days in order to remove DMF. The dye-coated TiO₂ thin film was washed with ethanol, and a solar cell was manufactured according to common solar cell manufacturing method.

Wherein, redox electrolyte solution obtained by dissolving 0.05 M I₂, 0.1 M LiI, 0.6 M l,2-dimethyl-3-hexylimidazolium iodide and 0.5 M 4-tert-butylpyridine in methoxypropionitrile was used.

Examples 9-16 and Comparative Example 1

Solar cells were manufactured by the same process as Example 8, except that DCSC 2(Example 9), DCSC 3(Example 10), DCSC 4(Example 11), DCSC 8(Example 12, using compound of the Chemical Formula 1-6), DCSC 9(Example 13), compound of the Chemical Formula l-14(l)(Example 14), compound of the Chemical Formula 1- 14(2)(Example 15), compound of the Chemical Formula l-16(Example 16) and N719 were respectively used as dye instead of DCSC 1. The photoelectrochemical characteristics, IPCE, absorption spectrum and molar absorption coefficient of the manufactured solar cells were measured, and the results are shown in Fig. 1. The following Table 1 shows absorption peak and molar absorption coefficient, Table 2 shows J_sc(short-circuit photocurrent density), V_oc(open circuit voltage), FF(fill factor), and photoelectric transformation efficiency(η).

The photoelectrochemical characteristics of the solar cells were measured using Keithley M 236 source measure unit, with a 300 W Xe lamp equipped with AM 1.5 filter(Oriel) as light source, electrode size of 0.4 x 0.4 cm², and light intensity of 1 sun(100 mW/cm²). Light intensity was controlled using Si solar cell. IPCE was measured using system of PV Measurement Company. The absorption spectrums of dyes in a solution and TiO₂ film were measured using HP 8453A diode array spectrophotometer. [Table 1]

As shown in the Table 1 and Fig. 1, the dyes of the present invention (including Chemical Formula l-14(l)(Example 14), Chemical Formula l-14(2)(Example 15), and Chemical Formula l-16(Example 16) which are not shown) have higher curves than Ref. dye N719 over the whole wavelength indicating higher molar absorption efficiency, and the curves shift toward long wavelength. [Table 2]

As shown in Table 2, the dyes of the present invention have higher curves than N719 over the whole wavelength, and have excellent photoelectric transformation efficiency.

[Industrial Applicability]

Claims

[CLAIMS]

[Claim 1 ]

Ru-type dye represented by the following Chemical Formula 1 :

(wherein al ring is optionally substituted by one or more substituent selected from the group consisting of halogen atom, amide, cyano, hydroxyl, nitro, acyl, Ci_-30 alkyl and Ci- ₃o alkoxy group; and

X and Y are independently methyl or a represented by one of the following Chemical Formulas 2-1 to 2-14, and at least one of X and Y is represented by one of the following Chemical Formula 2-1 to 2-14:

(wherein (*) represents a bond, bl ring is optionally substituted by one or more substituent selected from the group consisting of halogen atom, amide, cyano, hydroxyl, nitro, acyl, C_1-30 alkyl and Ci_-30 alkoxy group; A is independently S or O; and, R, Ri, R₂ and R₃ are independently hydrogen, Cj_-I5 alkyl, Ci_-I5 alkoxy, C_6-20 aryl or C_6-20 heteroaryl; and, n is an integer of from 1 to 10).

[Claim 2] The Ru-type dye according to claim 1, wherein the dye is represented by one of the following Chemical Formulas 1-1 to 1-38:



(wherein A and R are as defined in claim 1).

[Claim 3]

A method for preparing a dye represented by the following Chemical Formula 1, which comprises the step of reacting a compound of the following Chemical Formula 3 with compounds of the following Chemical Formula 4, Chemical Formula 5, and Chemical Formula 6 in order:

[Chemical Formula 4] [RuCl₂(p-cymene)]₂

[Chemical Formula 5]

(wherein X, Y and al are as defined in claim 1).

[Claim 4]

The method according to claim 3, wherein the dye is prepared by the process according to one of the following Reaction Formulas 1 to 6:

(in the Reaction Formula 4, R is independently hydrogen, Ci_-I5 alkyl, Cj_-I5 alkoxy, C_6-20 aryl or C_6-20 heteroaryl)



[Claim 5]

A dye-sensitized photoelectric transformation element comprising oxide semiconductor particles, wherein the dye according to claim 1 is supported on the oxide semiconductor particles.

[Claim 6)

The dye-sensitized photoelectric transformation element according to claim 5, wherein the dye is supported on the oxide semiconductor particles in the presence of an inclusion compound.

[Claim 7]

The dye-sensitized photoelectric transformation element according to claim 5, wherein the oxide semiconductor particles essentially comprise titanium dioxide.

[Claim 8]

The dye-sensitized photoelectric transformation element according to claim 5, wherein the semiconductor oxide particles have the average diameter of 1 - 50 nm.

[Claim 9]

A dye-sensitized solar cell comprising the dye-sensitized photoelectric transformation element according to claim 5. [Claim 10]

The dye-sensitized solar cell according to claim 9, wherein the dye-sensitized solar cell is prepared by: coating titanium oxide paste on a transparent conductive substrate; sintering the coated substrate to form a titanium oxide thin film; immersing the substrate having a titanium oxide thin film formed thereon in a mixed solution in which the dye represented by the Chemical Formula 1 is dissolved, so as to form a dye-absorbed titanium oxide film electrode; providing a second glass substrate having a counter electrode formed thereon; forming a hole penetrating the second glass substrate and the counter electrode; placing thermoplastic polymer film between the counter electrode and the dye-absorbed titanium oxide film electrode and heat-pressing them to join the counter electrode and the titanium oxide film electrode; injecting electrolyte into the thermoplastic polymer film placed between the counter electrode and the titanium oxide film electrode through the hole; and, sealing the thermoplastic polymer.