Patent Application
20120160326
This application claims the benefit of Korean Patent Application No. 10-2010-0134885, filed on Dec. 24, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field
One or more embodiments relate to a photoelectrode for a dye-sensitized solar cell, a solar cell including the photoelectrode, and a method of manufacturing the photoelectrode.
2. Description of the Related Technology
Dye-sensitized solar cells are photoelectrochemical solar cells including photo-sensitive dye molecules that absorb visible light, unlike a silicon solar cell, to generate an electron-hole pair, and a transition metal oxide for transferring generated electrons.
Dye-sensitized solar cells are transparent and have relatively low manufacturing costs compared to a conventional silicon solar cell, and thus, they can be used in glass windows in an outer wall of a building or in a glass greenhouse. However, dye-sensitized solar cells still need to be improved to achieve low haze and high transmittance, which is required in a building-integrated photovoltaic (BIPV) system.
One or more embodiments include a method of manufacturing a photoelectrode for a dye-sensitized solar cell having low haze and high transmittance, which is required in a building-integrated photovoltaic (BIPV) system, a method of manufacturing the photoelectrode, and a dye-sensitized solar cell including the photoelectrode.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.
According to one or more embodiments, a photoelectrode for a dye-sensitized solar cell, the photoelectrode includes a coating product of a composition including a metal oxide, an acid, a first additive including one or more compounds represented by Formula 1 below, and a second additive including one or more compounds represented by Formula 2 below:
wherein Formula 1, Ra is a C10 to C30 alkyl group, X is a hydrogen atom or —(CH2CH2O)n—Rb, n is an integer of 1 to 20, and Rb is a C10 to C30 alkyl group, and
wherein Formula 2, Rc is a C10 to C30 alkyl group, and n is an integer of 1 to 20.
According to one or more embodiments, a method of preparing a photoelectrode for a dye-sensitized solar cell, includes: preparing a first composition by mixing a metal oxide, a first solvent, and an acid; preparing a second composition by adding a first additive including one or more compounds represented by Formula 1 below to the first composition:
wherein Formula 1, Ra is a C10 to C30 alkyl group, X is a hydrogen atom or —(CH2CH2O)n—Rb, n is an integer of 1 to 20, Rb is a C10 to C30 alkyl group;
preparing a third composition by adding a binder and a second solvent to the second composition;
preparing a metal oxide composition by adding a second additive comprising one or more compounds represented by Formula 2 below to the third composition:
wherein Formula 2, Rc is a C10 to C30 alkyl group, and n is an integer of 1 to 20; and coating and heat treating the metal oxide composition on a substrate.
According to one or more embodiments, a dye-sensitized solar cell includes: a first electrode; the photoelectrode described above formed on a surface of the first electrode; a second electrode disposed facing the first electrode on which the photoelectrode is disposed; and an electrolyte disposed between the first electrode and the second electrode.
These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description.
A photoelectrode for a dye-sensitized solar cell, according to an embodiment, includes a coating product of a composition including a metal oxide, an acid, a first additive including one or more compounds represented by Formula 1 below, and a second additive including one or more compounds represented by Formula 2 below:
wherein Formula 1, Ra is a C10 to C30 alkyl group, X is a hydrogen atom or —(CH2CH2O)n—Rb, n is an integer of 1 to 20, Rb is a C10 to C30 alkyl group, and
wherein Formula 2, Rc is a C10 to C30 alkyl group, and n is an integer of 1 to 20.
A mole ratio of the first additive to the second additive is 1:4 to 4:1.
The first additive may be used as a dispersing agent, and an amount of the first additive is about 1 to about 15 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the first additive is within the range described above, the composition may have good dispersing characteristics and a relatively small particle size.
The first additive may be a mixture including a compound represented by Formula 3 below and a compound represented by Formula 4 below. An amount of the mixture may be about 1 to about 15 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the mixture is within the range described above, the composition may have good dispersing characteristics and a relatively small particle size.
A mole ratio of the compound of Formula 3 to the compound of Formula 4 may be 1:4 to 4:1, for example, 1:2 to 2:1. If the mole ratio of the compound of Formula 3 to the compound of Formula 4 is within this mole ratio range, the composition may have good dispersing characteristics, and a relatively small particle size.
wherein Formulae 3 and 4, n is an integer of 1 to 14.
The second additive including one or more compounds represented by Formula 2 may be used as a dispersing agent, and an amount of the second additive is about 1 to about 15 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the second additive is within the range described above, the composition may have good dispersing characteristics. Also, the composition may have good viscosity characteristics at a low shear rate and thus good printing characteristics.
The second additive may be a mixture comprising a compound represented by Formula 5 below and a compound represented by Formula 6. An amount of the mixture may be about 1 to about 15 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the mixture is within the range described above, the composition may have good dispersing characteristics. Also, the composition may have good viscosity characteristics at a low shear rate and thus good printing characteristics.
A mole ratio of the compound of Formula 5 to the compound of Formula 6 may be from about 1:4 to about 4:1, for example from about 1:2 to about 2:1. If the mole ratio of the compound of Formula 5 to the compound of Formula 6 is within the mole ratio range, the composition may have good dispersing characteristics. Also, the composition may have good viscosity characteristics at a low shear rate and thus good printing characteristics.
wherein Formulae 5 and 6, n is an integer of 1 to 14.
In order to manufacture the photoelectrode, the composition may be coated on a transparent substrate to form a metal oxide layer. In this regard, the coating method is not limited, and may be spraying, spin coating, dipping, printing, doctor blading, sputtering, etc.
After the coating, drying and calcinating may be performed. The drying may be performed at a temperature of about 50 to about 180° C., and the calcinating may be performed at a temperature of about 400 to about 600° C.
The photoelectrode may further include a dye on the metal oxide layer. Dye particles are adsorbed to a surface of metal oxide of the metal oxide layer, and absorb light so that electrons transition from a ground state to an excited state to form an electron-hole pair and the excited electrons are injected to a conduction band of the metal oxide and move toward the photoelectrode, thereby generating an electromotive force.
A dye for use in the photoelectrode may be any one of various dyes that have charge separation characteristics, are dye-sensitized, and used in a conventional solar cell. For example, the dye may be a ruthenium complex. The dye may also be, in addition to a ruthenium complex, an xanthine pigment, such as rhodamine B, rose bengal, eosine, or erythrocin; a cyanine-based pigment, such as quinocyanine or cryptocyanine; a basic dye, such as phenosafranine, capriblue, tyocyn, or methylenblue; a porphyrin-based compound, such as chlorophyll, zinc porphyrin, or magnesium prophyrin; an azo pigment; a complex, such as a phthalocyanin compound, or a Ru trisbipyridyl; an anthraquinone-based pigment; a multi-cyclic quinine-based pigment; or a combination thereof. The ruthenium complex may be RuL2(SCN)2, RuL2(H2O)2, RuL3, or RuL2 where L is 2,2′-bipyridyl-4,4′-dicarboxylate.
A method of manufacturing a photoelectrode for a dye-sensitized solar cell, according to an embodiment, includes preparing a metal oxide composition for forming a photoelectrode for a dye-sensitized solar cell.
The method of manufacturing a photoelectrode for a dye-sensitized solar cell includes: preparing a first composition by mixing a metal oxide, a first solvent, and an acid; preparing a second composition by adding a first additive including one or more compounds represented by Formula 1 to the first composition; preparing a third composition by adding a binder and a second solvent to the second composition; preparing a metal oxide composition by adding a second additive comprising one or more compounds represented by Formula 2 to the third composition; and coating and heat treating the metal oxide composition on a substrate.
The preparing of the first composition may further include sonicating the first composition prepared by mixing the metal oxide, the first solvent, and the acid.
The method may further include milling of the second composition prepared by adding the first additive including one or more compounds represented by Formula 1 to the first composition. The milling may not be limited and may be, for example, Apex milling.
The first solvent may be any one of various solvents that uniformly disperse the metal oxide, and nonlimiting examples of the first solvent are water, acetone, methanol, ethanol, isopropylalcohol, n-propylalcohol, butanol, α-α-terpineol, dimethylacetamide, dimethylformamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, tetrahydrofurane, tetrabutylacetate, n-butylacetate, 2-(2-butoxyethoxy)ethyl acetate), m-cresol, toluene, ethylgylcol, gamma-butyrolactone, hexafluoroisopropanol (HFIP), N,N-dimethylforamide (DMF), hexane, and a combination thereof.
The first additive may be used as a dispersing agent, and the first additive may include one or more compounds represented by Formula 1.
Also, an amount of the first additive is about 1 to about 15 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the first additive is within the range described above, the second composition may have good dispersing characteristics. Also, the addition of the first additive may lead to a smaller particle size of the second composition.
The first additive may be a mixture of a compound represented by Formula 3 and a compound represented by Formula 4. A mole ratio of the compound of Formula 3 to the compound of Formula 4 may be from about 1:4 to about 4:1. If the mole ratio of the compound of Formula 3 to the compound of Formula 4 is within the mole ratio range, the second composition may have good dispersing characteristics. Also, due to the addition of the first additive, the second composition has a relatively smaller particle size.
The second additive may be used as a dispersing agent, and the second additive may include one or more compounds represented by Formula 2.
An amount of the second additive is from about 1 to about 15 parts by weight based on 100 parts by weight of the metal oxide. If the amount of the second additive is within the range described above, the metal oxide composition may have good dispersing characteristics. Also, the metal oxide composition may have good viscosity characteristics at a low shear rate and thus good printing characteristics.
The second additive may be a mixture including a compound represented by Formula 5 and a compound represented by Formula 6.
A mole ratio of the compound of Formula 5 to the compound of Formula 6 may be from about 1:4 to about 4:1. If the mole ratio of the compound of Formula 5 to the compound of Formula 6 is within the mole ratio range, the metal oxide composition may have good dispersing characteristics. Also, the metal oxide composition may have good viscosity characteristics at a low shear rate and thus good printing characteristics.
In the preparing of the third composition, the binder is dissolved in the second solvent and the second solvent is additionally added to the resultant mixture.
The second solvent may be any one of the examples of the first solvent as presented above.
In the preparing of the metal oxide composition, the second additive is added to the third composition to allow the third composition to be easily dispersed so as to adjust a viscosity of the metal oxide composition to be such a level that the metal oxide composition is easily coated on the substrate. The metal oxide composition is coated on the substrate and heat treated to complete manufacturing of the photoelectrode. When the second additive is added to the third composition, a viscosity of the metal oxide composition at a low shear rate is low. The decrease in viscosity at a low shear rate is confirmed with reference to
The metal oxide may include TiO2, SnO2, WO3, ZnO, SiO2, ZrO2, MgO, SrTiO3, Al2O3, or a combination thereof.
The acid may be, for example, a nitric acid, a hydrochloric acid, or an acetic acid, but is not limited thereto.
The binder may be one selected from the group consisting of methylcellulose, ethylcellulose, propylcellulose, nitrocellulose, acetacidcellulose, propionacidcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethylhydroxypropyl cellulose, and a combination thereof, but is not limited thereto.
A dye-sensitized solar cell according to an embodiment includes a first electrode; a photoelectrode formed on a surface of the first electrode; a second electrode disposed facing the first electrode on which the photoelectrode is disposed; and an electrolyte disposed between the first electrode and the second electrode.
Referring to
In the present embodiment, the first substrate 10 functions as a support for the first electrode 11 and is transparent to allow external light to enter inside the dye-sensitized solar cell. The first substrate 10 may include glass or a plastic material. Examples of a plastic material are poly ethylene terephthalate (PET), poly ethylene naphthalate (PEN), poly carbonate (PC), poly propylene (PP), poly imide (PI), and tri acetyl cellulose (TAC).
The first electrode 11 formed on the first substrate 10 may include one selected from the group consisting of indium tin oxide, indium oxide, tin oxide, zinc oxide, sulfur oxide, fluorine oxide, ZnO—Ga2O3 or ZnO—Al2O3, and a combination thereof. The first electrode 11 may be a single or stacked layer comprising the transparent materials.
The photoelectrode 13 is formed on the first electrode 11. The photoelectrode 13 may have a thickness of about 10 nm to about 3000 nm, for example, about 10 nm to about 1000 nm. However, the thickness of the photoelectrode 13 may not be limited thereto and may vary according to a degree of technology development.
The dye 15 that absorbs external light to generate excited electrons is adsorbed to a surface of the photoelectrode 13.
The dye 15 may be an organic dye that has a high mole absorption coefficient, high photoelectric efficiency, and low manufacturing costs, as an alternative to an inorganic dye that is used in conventional cases and is expensive.
The second substrate 20 facing the first substrate 10 functions as a support for the second electrode 21, and may be transparent. Like the first substrate 10, the second substrate 20 may include glass or a plastic material.
The second electrode 21 formed on the second substrate 20 may be disposed facing the first electrode 11, and may include a transparent electrode 21a and a catalyst electrode 21b.
The transparent electrode 21a may include a transparent material, such as an indium tin oxide, a fluoro tin oxide, an antimony tin oxide, a zinc oxide, a tin oxide, ZnO—Ga2O3, or ZnO—Al2O3. The transparent electrode 21a may be a single or stacked layer of the transparent materials. The catalyst electrode 21b may activate a redox couple, and examples thereof are platinum, ruthenium, palladium, iridium, rhodium (Rh), osmium (Os), carbon (C), WO3, TiO2, etc.
The first substrate 10 is bonded to the second substrate 20 by an adhesive 41, and the electrolyte 30 is injected via a hole 25a that passes through the second substrate 20 and the second electrode 21 so that the first electrode 11 and the second electrode 21 are impregnated with the electrolyte 30. The electrolyte 30 uniformly disperses into the photoelectrode 13. The electrolyte 30 receives electrons from the second electrode 21 by oxidation and reduction and transfers the electrons to the dye 15. The hole 25a that passes through the second substrate 20 and the second electrode 21 is sealed by the adhesive 42 and a cover glass 43.
Although not illustrated in
The porous film may include metal oxide particles, such as titanium dioxide, zinc oxide, tin oxide, strontium oxide, indium oxide, iridium oxide, lanthan oxide, vanadium oxide, molybdenum oxide, tungsten oxide, niobium oxide, magnesium oxide, aluminium oxide, yttrium oxide, scandium oxide, samarium oxide, galluim oxide, or strontium titanium oxide. For example, the metal oxide particles may include titanium dioxide (TiO2), tin oxide (SnO2), tungsten oxide (WO3), zinc oxide (ZnO), or a combination thereof.
The present embodiments will be described in further detail with reference to the following examples. These examples are for illustrative purposes only and are not intended to limit the scope of the present embodiments.
In order to disperse TiO2 powder having an average particle diameter of 20 nm, a first composition including 170 g of TiO2 powder, 830 g of ethanol, and 10 ml of nitric acid were sonificated for 1 hour. Then, 8.5 g of a mixture including a compound represented by Formula 3 and a compound represented by Formula 4 at a mole ratio of 2:1 was added to the first composition to prepare a second composition. The second composition was dispersed by using an Apex mill for 4 hours.
510 g of a vehicle prepared by adding 51 g of ethyl cellulose to 137.7 g of 2-(2-butoxyethoxy)ethyl acetate and 321.3 g of α-terpineol to liquidize, and 320 g of a solvent including 2-(2-butoxyethoxy)ethyl acetate and α-terpineol at a weight ratio of 3:7 were added to the dispersed second composition to prepare a third composition. 5.1 g of a mixture including a compound represented by Formula 5 and a compound represented by Formula 6 at a mole ratio of 1:2 was added to the third composition, thereby completing preparation of a TiO2 composition.
A TiO2 composition for forming an amine-based photoelectrode was prepared in the same manner as in Example 1, except that an amine-based compound was used instead of the mixture including the compound represented by Formula 3 and the compound represented by Formula 4 at a mole ratio of 2:1, and the mixture including the compound represented by Formula 5 and the compound represented by Formula 6 at a mole ratio of 1:2 was not used. Anti-Terra-U (product of BYK Company), which is a low-molecular-weight acid polymer unsaturated polyamine amide salt solution, was used as the amine-based compound.
A TiO2 composition for forming a photoelectrode was prepared in the same manner as in Example 1, except that the mixture including the compound represented by Formula 5 and the compound represented by Formula 6 at a mole ratio of 1:2 was not used.
Table 1 shows final particle diameters (nm) of the second compositions prepared by using the mixture including the compound represented by Formula 3 and the compound represented by Formula 4 in Example 1 and Comparative Example 2, and the amine-based composition prepared according to Comparative Example 1:
As shown in Table 1, it was confirmed that the particle sizes of the second compositions prepared by using the mixture including the compound represented by Formula 3 and the compound represented by Formula 4 in Example 1 and Comparative Example 2 were less than that of the amine-based composition of Comparative Example 1.
The mixture including the compound represented by Formula 5 and the compound represented by Formula 6 at a mole ratio of 1:2 was used to change the rheology of the metal oxide composition to be appropriate for printing. Regarding printing, in general, viscosity at a low shear rate is an important factor. Referring
The TiO2 composition prepared according to Example 1 was subjected to coating and drying, and then, heat-treating at a temperature of 500° C. for about 30 minutes, thereby forming a TiO2 film, for example, a photoelectrode, having a thickness of about 12 μm.
A photoelectrode was manufactured in the same manner as in Example 2, except that the TiO2 composition prepared according to Comparative Example 1 was used.
Haze and transmittance of TiO2 films prepared according to Example 2 and Comparative Example 3 were measured and the results are shown in Table 2.
A particle size of a dispersed second composition is related to optical properties of a TiO2 film. For example, the smaller a particle size of a dispersed second composition, the lower the haze and the higher the transmittance.
As shown in Table 2, the haze of the TiO2 film prepared according to Example 2 is lower than the haze of the TiO2 film prepared according to Comparative Example 3. Accordingly, it is confirmed that a photoelectrode for a dye-sensitized solar cell, manufactured using a TiO2 composition prepared using the mixture including the compound represented by Formula 3 and the compound represented by Formula 4 at a mole ratio of 2:1 as a dispersing agent, is suitable for a BIPV system requiring low haze and high transmittance. Also, when the mixture including the compound represented by Formula 5 and the compound represented by Formula 6 at a mole ratio of 1:2 was used, viscosity of a composition including the mixture at a low shear rate was decreased, thereby improving printing characteristics.
The photoelectrode manufactured according to Example 2 was left at a temperature of 80° C., and then, dipped in a 0.3 mM dye dispersed solution prepared by dissolving 0.3653 g parts by weight of pigment N719 (Solaronix Co., Ltd.) that consists of a Ru complex in 1 L of ethanol for at least 12 hours to perform a dye adsorption treatment.
Then, the dye-adsorbed photoelectrode was washed with ethanol and dried at room temperature, thereby depositing the photoelectrode on a first electrode.
Separately, a glass substrate coated with FTO was prepared as a substrate for a reference electrode, and a conductive surface of the substrate was masked with an adhesive tape in such a way that an area of the masked portion of the conductive surface was 1.5 cm2. Then, the resultant structure was coated with H2PtCl6 solution by using a spin coater, and heat treated at a temperature of 500° C. for 30 minutes, thereby manufacturing a second electrode as a reference electrode.
An acetonitrile electrolyte including LiI (0.5M) and I (0.05M) was injected into a space between the first electrode and the reference electrode and the resultant structure was sealed to manufacture a dye-sensitized solar cell.
A dye-sensitized solar cell was manufactured in the same manner as in Example 3, except that the photoelectrode manufactured according to Comparative Example 3 was used.
It was confirmed that the dye-sensitized solar cell manufactured according to Example 2 had lower haze and higher transmittance than the dye-sensitized solar cell manufactured according to Comparative Example 3.
As described above, the photoelectrodes for a dye-sensitized solar cell, according to the one or more of the above embodiments have low haze and high transmittance, which are factors required in a BIPV system.
It should be understood that the example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2010-0134885 | Dec 2010 | KR | national |
