KR20120106633A - Cobalt type compound for dye-sensitized solar cell - Google Patents

Abstract

The present invention relates to a cobalt-based compound for solar cells, in particular, the cobalt-based compound of the present invention is used in the electrolyte system of the dye-sensitized solar cell to enable the production of thinner than conventional dye-sensitized solar cells, Corrosion is less, so the durability of the dye-sensitized solar cell can be improved, and in particular, the redox potential difference is large, so that the efficiency of the dye-sensitized solar cell can be improved.

Description

Cobalt type compound for dye-sensitized solar cell

The present invention relates to a cobalt-based compound for solar cells, in particular used in the electrolyte system of the dye-sensitized solar cell to enable the manufacture of a thin film than the conventional dye-sensitized solar cell, dye-sensitized solar cell is less corrosive to metal The present invention relates to a cobalt-based compound capable of improving the durability, and particularly, to increase the efficiency of a dye-sensitized solar cell with a large redox potential difference.

Since the development of dye-sensitized nanoparticle titanium oxide solar cells in 1991 by Michael Gratzel's team, much research has been done in this area. Dye-sensitized solar cells have the potential to replace conventional amorphous silicon solar cells because of their higher efficiency and lower manufacturing costs than conventional silicon-based solar cells. It is a photoelectrochemical solar cell whose main constituent material is a dye molecule capable of absorbing and generating electron-hole pairs, and a transition metal oxide for transferring generated electrons.

In general, electrolytes used in dye-sensitized solar cells utilize the redox system of Iodide / Triiodide. However, this system is corrosive to metals, which reduces the durability of dye-sensitized solar cells, and the small redox potential difference is a problem, and research on new electrolytes is ongoing.

Therefore, the present invention enables the manufacture of a thin film thinner than the conventional dye-sensitized solar cell, and the corrosion resistance to the metal can be improved to improve the durability of the dye-sensitized solar cell, especially the redox potential difference is large dye-sensitized solar cell It is an object of the present invention to provide a new electrolyte system and a dye-sensitized solar cell including the same, which can greatly improve the efficiency of the same.

In order to achieve the above object, the present invention provides a cobalt-based compound for dye-sensitized solar cells represented by the following formula (1).

[Formula 1]

In Formula 1,

Each A independently has two X's bonded to Co, and is represented by the following Chemical Formula 2 or Chemical Formula 3, at least one of the three As is a compound of Chemical Formula 3,

[Formula 2]

(3)

Each X is independently N or C,

R ₁ to R ₈ are each independently hydrogen, deuterium, halogen, amide, cyano, hydroxyl, nitro, acyl, unsubstituted or substituted with a substituent C _{1 -30} alkyl or C _{1 -30} alkoxy, C _{1 -30 Alkylcarbonyl} or C _6-20 aryl.

In another aspect, the present invention provides an electrolyte system for a dye-sensitized solar cell comprising a compound represented by the formula (1).

In another aspect, the present invention provides a dye-sensitized solar cell comprising the electrolyte system.

The cobalt-based compound of the present invention is used in the electrolyte system of the dye-sensitized solar cell to enable the manufacture of a thin film thinner than the conventional dye-sensitized solar cell, and less corrosion resistance to the metal can improve the durability of the dye-sensitized solar cell In particular, the redox potential difference is large to improve the efficiency of the dye-sensitized solar cell.

The present invention provides a cobalt-based compound represented by the following formula (1) that can be used as an electrolyte of a dye-sensitized solar cell.

[Formula 1]

In Formula 1,

Each A independently has two X's bonded to Co, and is represented by the following Chemical Formula 2 or Chemical Formula 3, at least one of the three As is a compound of Chemical Formula 3,

[Formula 2]

(3)

Each X is independently N or C,

R ₁ to R ₈ are each independently hydrogen, deuterium, halogen, amide, cyano, hydroxyl, nitro, acyl, unsubstituted or substituted with a substituent C _{1 -30} alkyl or C _{1 -30} alkoxy, C _{1 -30 Alkylcarbonyl} or C _6-20 aryl.

Preferably, the compound represented by Chemical Formula 1 is one of the compounds represented by any one of the following Chemical Formulas 4 to 9.

[Formula 4]

[Chemical Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Chemical Formula 9]

In Formulas 4 to 9, R ₁ to R ₈ are as defined above.

More preferably, the compound represented by Formula 1 may be one of the compounds shown below.

Preparation of the compound represented by Chemical Formula 1 is carried out by refluxing with a combination of CoCl ₂ ㅇ H ₂ O and A ligand substituted with R ₁ to R ₈ as defined above, and then adding an excess salt to filter the compound 4 to 6 Co (II) complexes represented by the above formula can be obtained, and Co (III) complexes represented by the formulas (7) to (9) can be obtained by oxidizing the Co (II) complexes with an oxidizing agent such as NOBF ₄ and adding a salt such as ammonium hexafluorophosphate. A complex can be obtained.

In another aspect, the present invention provides a dye-sensitized solar cell comprising an electrolyte system and the electrolyte system comprising a compound represented by the formula (1).

The electrolyte of the present invention uses a compound represented by Chemical Formula 1 in place of a system using a redox couple of the conventional Iodide / Triiodide, the electrolyte system according to the present invention is produced in a thin film than the conventional dye-sensitized solar cell And it is possible to improve the durability of the dye-sensitized solar cell is less corrosive to the metal, especially the redox potential difference can significantly improve the efficiency of the dye-sensitized solar cell.

The electrolyte system of the present invention may be applied to the known electrolyte system except that the compound represented by Chemical Formula 1 is used instead of the conventional redox couple of Iodide / Triiodide. For example, the methods described in Korean Patent Application Publication No. 10-2009-38377 (Dongjin Semichem Co., Ltd.) may be applied. Preferably, the solvent is acetonitrile, propylene carbonate, ethylene carbonate, 3-methoxypropionitrile. , Methoxyacetonitrile, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, butyrolactone, dimethoxyethane, dimethyl carbonate, 1,3-dioxolane, methyl formate, 2-methyltetrahydrofuran, 3-methoxy-oxazolidin-2-one, sulfolane, tetrahydrofuran, water, and the like, in particular acetonitrile, propylene carbonate, ethylene carbonate, 3-methoxypropionitrile, ethylene glycol, 3- Methoxy-oxazolidin-2-one, butyrolactone, etc. are preferable, The said solvent can be used 1 type or in mixture.

Also preferably, the concentration of the redox electrolyte is preferably 0.01-5 M, more preferably 0.05-0.5 M.

In addition, the solar cell of the present invention is applied to the matters related to the production of known dye-sensitized solar cells, except for using the electrolytic chamber system of the present invention, for example, Korean Patent Publication No. 10-2009-38377 ( Applicants described in the applicant Dongjin Semichem Co., Ltd. can be applied, and as an example, a counter electrode (anode) is disposed between and opposed to a photoelectric conversion element (cathode) carrying dye on oxide semiconductor fine particles on a substrate. It can be obtained by filling a solution containing a redox electrolyte.

The dye-sensitized solar cell according to the present invention can be manufactured into a thinner film than the conventional dye-sensitized solar cell by using the cobalt-based compound represented by Chemical Formula 1 as an electrolyte, and less corrosive to metals. Durability is improved, in particular, the redox potential difference is large, it is possible to improve the efficiency of the dye-sensitized solar cell.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

Example 1

CoCl _2? 6H ₂ O 0,25 g the mixture was stirred and then placed in 5 ml of distilled water. 0.64 g of 1,10-phenantholine substituted with deuterium was dissolved in methanol, followed by drop wise stirring. After 5 minutes, potassium tetracyanoborate (1.2 g) was dissolved in distilled water and added. At this time, the resulting precipitate was filtered, washed with distilled water and dried under vacuum to obtain the following compound.

Example 2

CoCl _2? 6H ₂ O 0,25 g the mixture was stirred and then placed in 5 ml of distilled water. 0.64 g of 1,10-phenanthroline substituted with deuterium was dissolved in methanol, followed by drop wise stirring. After 5 minutes, the bromine solution of the same number of moles as 1,10-phenanthroline was added to the methanol, followed by stirring for 5 minutes. At this time, the resulting precipitate was filtered off and dried by distillation under reduced pressure. The dried product was dissolved in 15 ml of methanol again, and then 1.2 g of Potassium tetracyanoborate dissolved in distilled water was added. At this time, the resulting precipitate was filtered, washed with distilled water and dried under vacuum to obtain the following compound.

Example 3

In Example 1, the following compound was synthesized using 5,6-dimethyl-1,10-phenanthroline substituted with deuterium instead of 1,10-phenanthroline substituted with deuterium.

Example 4

The following compound was synthesized using 5,6-dimethyl-1,10-phenanthroline substituted with deuterium instead of 1,10-phenanthroline substituted with deuterium in Example 2.

Example 5

30 ml of 2-ethoxyethanol and 10 ml of distilled water were added to a round bottom flask, and 0,25 g of CoCl ₂ ˜6H ₂ O and 0.4 g of 1,10-phenanthroline were added and refluxed under a nitrogen atmosphere for 12 hours. Upon completion of the reaction, the product was cooled to room temperature, 10 ml of distilled water was added, the solid product was filtered, washed with ethanol and hexane, and completely dried to obtain a cobalt dimer complex. Next, 3.5 equivalents of 2,2-bipyridine and 0.5 g of sodium carbonate were added to the dimer complex in a round bottom flask, and 30 ml of 2-ethoxyethanol was added thereto. The mixture was refluxed for 12 hours, and when the reaction was completed, the mixture was cooled to room temperature, 10 ml of distilled water was added, and the solid product was filtered. After washing with ether and hexane and completely dried to obtain the following compound.

Example 6

In Example 5, the following compound was synthesized using Phenyl pyridine instead of 2,2-bipyridine.

Example 7

Put 30 ml of 2-ethoxyethanol and 10 ml of distilled water into a round bottom flask and add 0,25 g of CoCl ₂ -6H ₂ O and 0.3 g of 2,2-bipyridine1. The mixture is refluxed for 12 hours under a nitrogen atmosphere. Upon completion of the reaction, the product was cooled to room temperature, 10 ml of distilled water was added, the solid product was filtered, washed with ethanol and hexane and completely dried to obtain a cobalt dimer complex. Next, add 3.5 equivalents of 1,10-phenanthroline and 0.5 g of sodium carbonate to the round bottom flask in a round bottom flask to add 30 ml of 2-ethoxyethanol. The mixture is refluxed for 12 hours and when the reaction is complete the mixture is cooled to room temperature. 10 ml of distilled water was added thereto, and then the solid product was filtered and dried in vacuo to obtain the following compound.

Example 8

In Example 7, the following compound was synthesized using Phenyl pyridine instead of 2,2-bipyridine.

Example 9 Cobalt-Based Electrolyte Preparation

0.165 M of the compound prepared in Example 1, 0.045 M of the compound prepared in Example 2, 0.1 M of LiClO ₄ , and 0.8 M of tert-butylpyridine were dissolved in acetonitrile to prepare an electrolyte.

Example 10 Preparation of Cobalt-Based Electrolyte

0.165 M of the compound prepared in Example 3, 0.045 M of the compound prepared in Example 4, 0.1 M of LiClO ₄ , and 0.8 M of tert-butylpyridine were dissolved in acetonitrile to prepare an electrolyte.

Comparative Example 1 Preparation of Iodine-Based Electrolyte

An electrolyte was prepared by dissolving 0.6 M BMII, 0.03 M Iodine, 0.1 M guandeniumthiocyanate, 0.5 M tert-butylpyridine, and 0.02 M LiI in valeronitrile / acetonitrile (15:85 v / v).

Example 11 Fabrication of Dye-Sensitized Solar Cell

A dye-sensitized solar cell was prepared using the dye represented by the following compound and the electrolyte prepared in Example 9.

More specifically, a 2 μm thick first TiO ₂ layer was prepared on an FTO glass substrate, and a scattering layer of 3.35 μm thick was prepared for light scattering. The prepared TiO ₂ electrode was impregnated with a solution of dye (the following dye dissolved in a solvent composed of 0.1 mM tert-butanol and acetonitrile 1: 1; v / v) for 7 hours to adsorb the dye. In addition, a counter electrode was prepared by coating platinum on an FTO substrate.

Example 12 Fabrication of Dye-Sensitized Solar Cell

A dye-sensitized solar cell was manufactured in the same manner as in Example 11, except that the electrolyte of Example 10 was used instead of the electrolyte of Example 9 as the electrolyte system in Example 11.

Comparative Example 2 Fabrication of Dye-Sensitized Solar Cell

A dye-sensitized solar cell was manufactured in the same manner as in Example 11, except that the electrolyte of Comparative Example 1 was used instead of the electrolyte of Example 9 as the electrolyte system in Example 11.

Experiment

Voc, Jsc, FF and η (%) of the prepared dye-sensitized solar cell were measured, and the results are shown in Table 1 below.

Voc (mV) Jsc (mA cm-2) FF Efficiency (η) (%) Cell area Example 11 740.003 4.982 70.94 2.62 0.247 Example 12 742.046 4.757 72.28 2.55 0.250 Comparative Example 2 704.753 4.482 67.86 2.14 0.244

      As shown in Table 1, the electrolyte system according to the present invention showed excellent photoelectric conversion efficiency in the thin film, and particularly, in Example 11, it showed more excellent efficiency.

Claims (5)

Cobalt-based compound for solar cells represented by the formula (1):
[Formula 1]

In Chemical Formula 1,
Each A independently has two X's bonded to Co, and is represented by the following Chemical Formula 2 or Chemical Formula 3, at least one of the three As is a compound of Chemical Formula 3,
(2)

(3)

Each X is independently N or C,
R ₁ to R ₈ are each independently hydrogen, deuterium, halogen, amide, cyano, hydroxyl, nitro, acyl, unsubstituted or substituted with a substituent C _{1 -30} alkyl or C _{1 -30} alkoxy, C _{1 -30} an alkyl-carbonyl or C _{6 -20} aryl group. The method of claim 1,
Compound represented by Formula 1 is a cobalt-based compound for solar cells represented by any one of the following formulas 4 to 9:
[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

[Chemical Formula 9]

In Chemical Formulas 4 to 9,
R ₁ to R ₈ are each independently hydrogen, deuterium, halogen, amide, cyano, hydroxyl, nitro, acyl, unsubstituted or substituted with a substituent C _{1 -30} alkyl or C _{1 -30} alkoxy, C _{1 -30} an alkyl-carbonyl or C _{6 -20} aryl group. The method of claim 1,
Compound represented by the formula (1) is a cobalt-based compound for solar cells, characterized in that one of the compounds represented by the following formula:

A dye-sensitized solar cell electrolyte system comprising the cobalt-based compound of claim 1. A dye-sensitized solar cell comprising the electrolyte system of claim 4.