WO2011065601A1

WO2011065601A1 - Dye-sensitized solar cell including absorber layer in which plurality of nano tubes or nano rod type metal oxides are arrayed in one direction, and manufacturing method thereof

Info

Publication number: WO2011065601A1
Application number: PCT/KR2009/006978
Authority: WO
Inventors: 허완수; 이광훈
Original assignee: 숭실대학교 산학협력단
Priority date: 2009-11-25
Filing date: 2009-11-25
Publication date: 2011-06-03

Abstract

The present invention provides a dye-sensitized solar cell including a plurality of nano tubes, bridged nano tubes, and nano rod or bridged nano rod type metal oxides, and a manufacturing method thereof. The dye-sensitized solar cell comprises: a semiconductor electrode which includes a first transparent substrate and an absorber layer disposed on one side of the first transparent substrate; a counter electrode which is separably disposed in order to face the semiconductor electrode, and includes a second transparent substrate and a catalyst layer disposed to face the absorber layer on the second transparent substrate; and an electrolyte layer which is interposed between the semiconductor electrode and the counter electrode, wherein the absorber layer includes a plurality of metal oxides which have at least one type selected from a group that comprises nano tubes, bridged nano tubes, nano rods having an aspect ratio of 10 to 1000, and bridged nano rods having an aspect ratio of 10 to 1000, and dyes which are absorbed into the metal oxides. Thus, the dye-sensitized solar cell increases efficiency and saves manufacturing costs.

Description

Dye-sensitized solar cell having a plurality of nanotubes or nanorod metal oxide having a light absorption layer aligned in one direction and a method of manufacturing the same

The present invention relates to a dye-sensitized solar cell, and more particularly, to a dye-sensitized solar cell having improved efficiency due to improved electron mobility and reduced electron loss.

The present invention is derived from a study carried out as part of the industry-university cooperation project in Seoul as follows.

[Others] National R & D Projects Supporting This Invention

[Department name] Seoul

[Name of research project] Seoul-Academic-Industry Cooperation Project (2007 Technology Foundation Project)

Research Project Dye-Sensitized Solar Cell Using Titanium Oxide Nanorod

[Organization] Soongsil University Industry-Academic Cooperation Foundation

[Research Period] August 1, 2007 ~ July 31, 2008

The solar cell is a battery that generates electrical energy using solar energy, has the advantages of environmentally friendly, infinite energy source and long life. Such solar cells include silicon solar cells, semiconductor compound solar cells, and dye-sensitized solar cells.

Dye-sensitized solar cells are solar cells in which dye molecules that absorb sunlight and convert them into electrons are adsorbed on semiconductor oxide nanoparticle electrodes that provide a large specific surface area. Dye-sensitized solar cells have the advantage of low cost compared to other silicon solar cells and semiconductor compound solar cells.

1 is a view schematically showing an example of a conventional dye-sensitized solar cell.

Dye-sensitized solar cells generally include a semiconductor electrode 10, an electrolyte layer 13, and a counter electrode 20.

The semiconductor electrode 10 includes a transparent substrate 11 and a light absorption layer 12, and the light absorption layer 12 includes metal oxide nanoparticles 12a and a dye 12b.

The counter electrode 20 includes a transparent substrate 21 and a catalyst layer 22.

2 is a view schematically showing the operating principle of the dye-sensitized solar cell.

Referring to FIG. 2, sunlight hits the dye 12b that is incident through the transparent substrate 11 and adsorbed onto the surface of the metal oxide nanoparticles 12a. Here, since the dye 12b molecules are very small, the metal oxide nanoparticles 12a are used as a scaffold to adsorb a large number of dye 12b molecules to a given cell surface area. The sunlight hitting the dye 12b causes the dye 12b to be excited to emit electrons e ⁻ from the dye 12b. Electrons (e ⁻ ) emitted from the dye 12b are directly injected into the conduction band of the metal oxide nanoparticles 12a and are moved to the transparent substrate 11 by a chemical diffusion gradient. On the other hand, the dye 12b which has lost electrons obtains electrons by oxidizing iodine ions I ⁻ in the electrolyte layer 13 to 3 iodine ions I ^3- . 3 iodine ions I ^{3-in the} electrolyte mechanically diffuse to the counter electrode 20 and recover electrons lost by counter electrons flowing there through an external circuit.

In the conventional dye-sensitized solar cell having the above configuration, the metal oxide nanoparticles 12a each have a size of about 15 to 25 nm, and the plurality of nanoparticles 12a are electrically formed by forming a three-dimensional network. A well-connected particle film of about 20 μm thick is formed. However, since the metal oxide nanoparticles 12a constitute an irregular polycrystalline network, electrons generated from the dye 12b molecules are transported to the transparent substrate 11 at a slow speed, or the metal oxide nanoparticles 12a are transported. There is a problem that disappears in conjunction with). Moreover, since the particle film is so thick, there is a problem in that the incident sunlight loses a considerable amount of energy before reaching the dye 12b molecules, thereby reducing the proportion of sunlight finally absorbed by the dye 12b. These problems are obstacles to the high efficiency of conventional dye-sensitized solar cells.

An object of the present invention is to form a metal oxide in which the dye molecules are adsorbed on the surface in the form of nanotubes, bridge nanotubes, nanorods or bridge nanorods and arrange them side by side in a direction perpendicular to the smooth surface of the transparent substrate Forming a thin film, thereby increasing the amount of light absorbed by the dye per unit area of the dye, while reducing the travel distance from the metal oxide to the transparent substrate to efficiently transfer electrons to provide a dye-sensitized solar cell with improved efficiency It is.

The present invention to solve the above problems,

A semiconductor electrode comprising a first transparent substrate and a light absorption layer disposed on one surface of the first transparent substrate;

An opposite electrode disposed to face the semiconductor electrode, the counter electrode including a catalyst layer disposed to face the light absorption layer on a second transparent substrate and the second transparent substrate; And

An electrolyte layer interposed between the semiconductor electrode and the counter electrode;

The light absorption layer has a plurality of metal oxides having at least one type selected from the group consisting of nanotubes, bridge nanotubes, nanorods having an aspect ratio of 10 to 1000, and bridge nanorods having an aspect ratio of 10 to 1000, and adsorbed thereto. It provides a dye-sensitized solar cell comprising a dye.

In addition, the present invention to solve the above problems,

A method of manufacturing a dye-sensitized solar cell having a semiconductor electrode, an electrolyte layer, and a counter electrode, the production of the semiconductor electrode,

(a) preparing a transparent substrate;

(b) coating a metal on the transparent substrate;

(c) electrochemically anodizing the metal to form a plurality of metal oxides in the form of nanotubes or nanorods having an aspect ratio of 10 to 1000;

(d) heat treating the metal oxide to crystallize the particles; And

(e) it provides a method for producing a dye-sensitized solar cell comprising the step of adsorbing a dye to the metal oxide.

According to one embodiment of the invention, the method of manufacturing a dye-sensitized solar cell, between the step (c) and (d), the anodized metal oxide of the step (c) of the metal oxide Immersing in a solution containing the precursor and heating to form a plurality of metal oxides in the form of bridge nanotubes or bridge nanorods having an aspect ratio of 10 to 1000.

According to one embodiment of the invention, the coating of the metal is ion plating, magnetron sputtering, chemical vapor deposition, chemical vapor deposition (evaporation), spin coating (spin coating), thermal oxidation method ( thermal oxidation, computer jet printing technique, spray pyrolysis or photochemical deposition.

According to another embodiment of the present invention, the coating of the metal is made by the metal is incident on the transparent substrate in the direction normal and inclined of the smooth surface, while the transparent substrate is rotated.

According to another embodiment of the present invention, the anodic oxidation treatment of step (c) is performed in-situ.

According to another embodiment of the present invention, the plurality of metal oxides are arranged side by side in a direction perpendicular to the smooth surface of the first transparent substrate (or transparent substrate).

According to another embodiment of the invention, the metal comprises at least one of Ti and its alloys.

According to another embodiment of the present invention, the electrolyte used in the anodic oxidation treatment of step (c) includes hydrogen peroxide (H ₂ O ₂ ).

According to a preferred embodiment of the present invention, the electrolyte contains at least one ion selected from the group consisting of fluorine ion (F ⁻ ), chlorine ion (Cl ⁻ ) and sulfate ion (SO ₄ ²⁻ ).

According to another embodiment of the present invention, the electrolyte used in the anodizing of step (c) includes fluorine ions.

According to another embodiment of the present invention, the electrolyte layer is poly (vinylidene fluoride-co-poly (hexafluoropropylene)), polyacrylonitrile-based polymer, polyethylene oxide-based polymer and polyalkylacrylate-based polymer At least one selected from the group consisting of.

1 is a cross-sectional view schematically showing the structure of a conventional dye-sensitized solar cell.

2 is a view for explaining the operating principle of the dye-sensitized solar cell of FIG.

3 and 4 are cross-sectional views schematically showing the structure of the dye-sensitized solar cell according to an embodiment of the present invention.

5 and 6 are diagrams for explaining the operating principle of the dye-sensitized solar cell of Figures 3 and 4, respectively.

7 is a SEM photograph showing a metal oxide in the form of nanotubes provided in the dye-sensitized solar cell of FIG. 3.

FIG. 8 is a SEM photograph showing a metal oxide in the form of a bridge nanotube provided in the dye-sensitized solar cell of FIG. 3.

9 is a graph showing photocurrent-voltage characteristics of the dye-sensitized solar cells prepared in Examples 1-1 to 1-4, 2-1 to 2-4, and Comparative Examples 1 to 3. FIG.

10 and 11 are SEM photographs showing metal oxides in the form of nanorods provided in the dye-sensitized solar cell of FIG. 4.

12 and 13 are SEM photographs showing metal oxides in the form of bridge nanorods provided in the dye-sensitized solar cell of FIG. 4.

14 is a graph showing the photocurrent-voltage characteristics of the dye-sensitized solar cells prepared in Examples 3, 4 and Comparative Example 2.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the dye-sensitized solar cell according to a preferred embodiment of the present invention.

3 and 4, a dye-sensitized solar cell according to an embodiment of the present invention includes a semiconductor electrode 100, an electrolyte layer 103, and an opposite electrode 110.

The semiconductor electrode 100 includes a first transparent substrate 101 and a light absorption layer 102 disposed on one surface of the first transparent substrate 101.

The main material of the first transparent substrate 101 is not particularly limited as long as it has transparency, and for example, a glass substrate may be used. As a material for imparting conductivity to the transparent substrate 101, any material can be used as long as it has conductivity and transparency. However, tin oxide (for example, SnO ₂ ) or indium tin oxide (ITO) is preferable. .

Referring to FIG. 3, the light absorption layer 102 includes a plurality of metal oxides 102a1 and a dye 102b adsorbed thereto.

The metal oxides 102a1 each have a nanotube or bridge nanotube shape. Here, "nanotube" refers to a tube shape having a diameter of several nm to several tens of nm, and "bridge nanotube" refers to a shape in which the nanotubes are at least partially connected to each other by a bridge.

Referring to FIG. 4, the light absorption layer 102 includes a plurality of metal oxides 102a2 and a dye 102b adsorbed thereto.

The metal oxides 102a2 each have a nanorod or bridge nanorod shape having an aspect ratio of 10 to 1000. The aspect ratio of the metal oxide 102a2 in the form of a bridge nanorod means an aspect ratio of only the metal oxide 102a2 in the form of a nanorod except for the bridge. Here, the "nanorod" means a rod shape having a diameter of several nm to several tens of nm, and the "bridge nanorod" means a form in which the nanorods are at least partially connected to each other by a bridge. If the aspect ratio is less than 200nm, the thickness of the nanorod film is ultra-thin, so the absolute value of the generated photocurrent is lowered, which is undesirable. An increase in the rate at which electrons are bonded to the metal oxide 102a2 due to the increased moving distance is not preferable. In order to adjust the aspect ratio of the metal oxide 102a2 to a value within the above range, it is necessary to appropriately adjust the anodizing conditions of the metal, which will be described in detail later.

The metal oxides 102a1 and 102a2 may be disposed in parallel with each other in a direction perpendicular to the smooth surface of the first transparent substrate 101. Here, the term "vertical" or "side by side" does not mean only completely vertical or side by side, but also perpendicular or side by side to those of ordinary skill in the art in view of limitations in manufacturing technology in the art. It is a concept that includes a margin of error that can be recognized. However, the present invention is not limited thereto, and the metal oxides 102a1 and 102a2 may have a direction perpendicular to the smooth surface of the first transparent substrate 101 (that is, the normal direction of the smooth surface) and a predetermined angle inclined direction. It may be arranged as.

The metal oxides 102a1 and 102a2 may have a semiconductor property, and may be selected from a compound semiconductor or a compound having a perovskite structure in addition to a single semiconductor represented by silicon. The semiconductor is preferably an n-type semiconductor in which conduction band electrons become carriers under photo excitation to provide an anode current. Specific examples of the semiconductor include TiO ₂ (titanium dioxide), SnO ₂ , ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO _3, and the like. Particularly preferred semiconductors are anatase type TiO ₂ . In addition, the kind of semiconductor is not limited to these, These can be used individually or in mixture of 2 or more types.

Specific examples of the metal for forming the metal oxides 102a1 and 102a2 include Zn, Zr, Yr, Mo, In, Sc, W, Ti, Mn, Sn, Zr, V, Si, Cr, Mg, Al, Fe, Ba , Pb, La, Sr, Bi, Ta, Cu, Ca, Nb and at least one selected from the group consisting of alloys thereof.

The metal oxide having such a structure and structure is preferably a large surface area so that the dye adsorbed on the surface can absorb more light. To this end, the particle size of the metal oxide is preferably 1㎛ or less, more preferably 10 ~ 300nm, even more preferably 10 ~ 100nm.

A method of forming the metal oxide will be described in detail later.

The dye 102b can be used without particular limitation as long as it is generally used in the solar cell or photovoltaic field, but ruthenium complex is preferable. As the ruthenium complex, RuL ₂ (SCN) ₂ , RuL ₂ (H ₂ O) ₂ , RuL ₃ , RuL _2, etc. may be used (wherein L is 2,2′-bipyridyl-4,4′-dica). Carboxylates).

The dye 102b is not particularly limited as long as it has a charge separation function and exhibits a sensitive action. Therefore, in addition to the ruthenium complex, for example, xanthine-based pigments such as rhodamine B, rosebengal, eosin, and erythrosine, quinocyanine and kryptosh Basic dyes, such as cyanine pigment | dye, phenosaprine, cabrioblue, thiocin, and methylene blue, porphyrin type compounds, such as chlorophyll, zinc porphyrin, magnesium porphyrin, other azo pigments, phthalocyanine compound, Ru trisbipyri Complex compounds such as dill, anthraquinone dyes, polycyclic quinone dyes and the like may also be used, and these may be used alone or in combination of two or more thereof.

The thickness of the light absorption layer 102 including the metal oxides 102a1, 102a2 and the dye 102b is preferably 50 μm or less, more preferably 1 to 35 μm. That is, the light absorption layer 102 has a large series resistance for structural reasons, and an increase in series resistance leads to a decrease in conversion efficiency. It is possible to prevent the degradation of the conversion efficiency.

An electrolyte layer 103 is I ^- and comprises a reduced species, I ^- - / I ^{3 -} oxidation as a source of ions is LiI, NaI, alkyl iodide or imidazolium iodide, etc. are used, ^3-I Ions are produced by dissolving I ₂ in a solvent. As the medium of the electrolyte, a liquid such as acetonitrile or a polymer such as polyethylene oxide may be used. Carbonates, nitrile compounds, alcohols and the like may be used as the liquid medium, and in particular, carbonates such as propylene carbonate and nitrile compounds such as acetonitrile and methoxy acetonitrile may be used. As the polymer medium, polyacrylonitrile (PAN), polyethylene oxide (PEO), and / or polyalkylacrylate (poly (alkylacrylate)) may be used. In addition, as the polymer medium, poly (vinylidene fluoride) -co-poly (hexafluoropropylene) may be used (poly (vinylidene fluoride) -co-poly (hexafluoropropylene)). It is also possible to prepare and use a gel electrolyte by adding a gelator to the liquid electrolyte.

The counter electrode 110 includes a second transparent substrate 111 and a catalyst layer 112 disposed on the second transparent substrate 111 so as to face the light absorbing layer 102.

The second transparent substrate 111 may be formed of the same or similar material as that of the first transparent substrate 101 described above.

As the material for forming the catalyst layer 112, any conductive material may be used without limitation, but any insulating material may be used as long as a conductive layer (not shown) is disposed on the side facing the semiconductor electrode 100. . However, it is preferable that an electrochemically stable material is used as an electrode, and specifically, platinum, gold, carbon, etc. are used.

Hereinafter, the operation of the dye-sensitized solar cell having the configuration of FIGS. 3 and 4 will be described in detail with reference to FIGS. 5 and 6.

3 to 6, light incident on the first transparent substrate 101 is absorbed by molecules of the dye 102b adsorbed to the metal oxides 102a1 and 102a2 of the semiconductor electrode 100. The light-absorbing dye 102b is excited to inject electrons into the conduction bands of the metal oxides 102a1 and 102a2. Electrons injected into the metal oxides 102a1 and 102a2 are transferred to the first transparent substrate 101 through an interparticle interface. Electrons transferred to the first transparent substrate 101 reach the counter electrode 110 through an external circuit as shown in FIGS. 5 and 6. In this case, the electrons arriving at the counter electrode 110 through the external circuit reach the catalyst layer 112 formed on the second transparent substrate 111.

On the other hand, the oxidation as a result of electron transfer dyes (102b) molecules electrolyte layer 103, an iodine ion redox action of the inside is reduced again accept electrons provided by the ^{_{^{^{(3I - → I 3 - -}}}} + 2e). The oxidized iodine ions I ^3- receive the electrons reaching the counter electrode 110 and are reduced again to complete the operation of the dye-sensitized solar cell.

Dye-sensitized solar cell according to an embodiment of the present invention having the configuration as described above forms a metal oxide disposed in the light absorption layer of the semiconductor electrode in the form of nanotubes, bridge nanotubes, nanorods or bridge nanorods and a transparent substrate By arranging in a direction perpendicular to the smooth surface of the light absorbing layer of the thin film having a short electron transfer path can be formed. As a result, the ratio of light incident on the first transparent substrate of the semiconductor electrode to be absorbed and lost by the metal oxide before reaching the dye may be reduced compared to the prior art, thereby increasing the light absorption rate per unit area of the dye. The optical efficiency can be improved by reducing the distance to the transparent substrate so that electrons can be efficiently transferred.

Hereinafter, a method of manufacturing a dye-sensitized solar cell according to an embodiment of the present invention will be described in detail.

First, a first transparent substrate for a semiconductor electrode is prepared.

Next, a metal is coated on one surface of the first transparent substrate. The coating of the metal may be ion plating, magnetron sputtering, chemical vapor deposition, evaporation, spin coating, thermal oxidation, computer jet printing techniques ( computer jet printing technique, spray pyrolysis, photochemical deposition, or the like.

Among the coating methods, ion plating is one of the methods in the field of Physical Vapor Deposition, and a material (that is, a first transparent substrate) is charged into a high vacuum chamber, and then an electron beam gun is used. It is a method of melting the metal to be deposited using the vapor deposition on the surface of the material.

The magnetron sputtering method is a method belonging to the physical vapor deposition field like the ion plating method. Unlike the ion plating method, a metal target is used without an electron beam gun, and the metal target is converted into argon (Ar) ion. It is a method of depositing particles of a metal target that is thrown out to the material.

In general, in vacuum deposition, metal molecules (atoms) evaporated from the evaporation material immediately fly to and deposit on the surface of the plated body, whereas in the case of ion plating or magnetron sputtering, the evaporated molecules are formed earlier than the plated body. The high-energy metal particles deposited on the film are electrically attracted to the plated body vigorously, thereby forming a much denser and harder film than vacuum deposition.

In this embodiment, the coating of the metal adjusts the angle of incidence of the metal such that the metal is incident on the first transparent substrate in the direction normal to the inclined direction and the inclined direction while the first transparent substrate is rotated. It is preferable to rotate the first transparent substrate at a predetermined speed. In this way, the metal can be uniformly coated on the first transparent substrate.

In the present embodiment, it is preferable to use titanium (Ti) as the metal and ion plating or magnetron sputtering method as the coating method.

In addition, in this embodiment, the deposition thickness of the metal is preferably 1㎛ or more. If the thickness is less than 1 μm, the thickness may be so thin that problems of anodic oxidation and corrosion resistance may occur.

The coated metal is then electrochemically anodized to form a plurality of metal oxides in the form of nanotubes or bridged nanotubes or to form a plurality of metal oxides in the form of nanorods or bridged nanorods.

First, the step of forming a plurality of metal oxides having a nanotube or bridge nanotube form by electrochemically anodizing the coated metal will be described. According to the manufacturing method of the present invention, the manufacturing cost can be reduced by performing a process of directly forming the metal oxide on the first transparent substrate, that is, an “in-situ” process. The anodic oxidation treatment impregnates the coated metal in an electrolyte including HF, NH ₄ F, HNO ₃ , KF, H ₂ SO ₄ , NaF, DMF, DMSO, and / or EG, and then anodes the metal. It is made by supplying platinum or the like as a cathode at 0 to 50 ° C. and energizing under the conditions of 5 to 250 V and 1 to 3 A / dm ² . When current flows in this way, an oxide film grows on the metal surface of the anode to form an anodized film (ie, a metal oxide in the form of nanotubes or bridge nanotubes). When anodizing is performed at a constant voltage, the current gradually decreases with time, and only a very small current flows. That is, when anodizing is performed at a constant voltage, an oxide film having an insulation breakdown voltage corresponding to the voltage is formed, and then the growth of the oxide film is stopped. The shape, diameter, and length of the metal oxide to be formed vary depending on the concentration of the electrolyte and voltage applied to the anodic oxidation. Specifically, the metal oxide in the form of nanotubes and the metal oxide in the form of bridge nanotubes are prepared through the same process until the anodic oxidation step, but in order to prepare the metal oxide in the form of bridge nanotubes, a sol containing a precursor of the metal oxide is used. The solution must be used to grow nanotube metal oxides in the form of bridges. That is, the metal oxide in the form of bridge nanotubes can be prepared by immersing an anodized metal oxide (having nanotube form) in a sol solution of the metal oxide and heating the mixture to grow a metal oxide bridge. Can be. In particular, when the metal to be coated on the first transparent substrate is Ti, the electrolyte used in the anodic oxidation treatment preferably contains fluorine ions.

In addition, the step of forming a plurality of metal oxides having a nanorod or bridge nanorod form by electrochemically anodizing the coated metal. Therefore, according to the manufacturing method of the present invention, it is possible to reduce the manufacturing cost by performing the process of forming the metal oxide directly on the first transparent substrate, that is, the "in-situ" process. The anodic oxidation treatment is NaX (X = F ⁻ , Cl ⁻ , SO ₄ ^2- , CO ₃ ^2- or C ₂ O ₄ ^2- ) and / or YCl (Y = Ta ⁵⁺ , Na ⁺ or H ⁺ ) and the like. Impregnated the coated metal in an electrolyte formed by dissolving in a hydrogen peroxide (H ₂ O ₂ ) solution, and then using the metal as an anode and platinum as a cathode at 1 to 50 V and 1 to 3 A / dm at 0 to 150 ° C. ^{It is} made by energizing on condition of ² . Even when anodizing is performed in an electrolyte containing only a hydrogen peroxide solution, it is possible to form a nanorod-shaped metal oxide, but the aspect ratio can be appropriately adjusted by further adding NaX and / or YCl to the electrolyte. When the current flows in this way, an oxide film grows on the metal surface of the anode to form an anodized film (that is, a metal oxide in the form of a nanorod or a bridge nanorod). When anodizing is performed at a constant voltage, the current gradually decreases with time, and only a very small current flows. That is, when anodizing is performed at a constant voltage, an oxide film having an insulation breakdown voltage corresponding to the voltage is formed, and then the growth of the oxide film is stopped. The shape, diameter, and length of the metal oxide to be formed vary depending on the concentration of the electrolyte and voltage applied to the anodic oxidation. Specifically, the metal oxides in the form of nanorods and the metal oxides in the form of bridge nanorods are prepared through the same process until the anodic oxidation step, but in order to produce the metal oxides in the form of bridge nanorods, a sol containing a precursor of the metal oxide is used. The solution must be used to grow nanorod metal oxides in the form of bridges. In other words, the metal oxide in the form of a bridge nanorod can be prepared by immersing an anodized metal oxide (having a nanorod form) in a sol solution of the metal oxide and heating the mixture to grow a metal oxide bridge. Can be. In particular, when the metal to be coated on the first transparent substrate is Ti, the electrolyte used in the anodic oxidation treatment preferably contains fluorine ions.

Next, the formed metal oxide in the form of nanotubes, bridge nanotubes, nanorods, or bridge nanorods is heated to crystallize the particles. This heat treatment is carried out at a temperature of 200 ~ 500 ℃, whereby the formed metal oxide is conductive.

Then, after the dye is adsorbed onto the metal oxide, a counter electrode prepared in advance is disposed to face the metal oxide, and the electrolyte composition containing the redox electron pair is embedded and sealed to complete the dye-sensitized solar cell.

Hereinafter, the present invention will be described with reference to the following specific examples, but the present invention is not limited to the following examples.

EXAMPLE

Example 1 Fabrication of Dye-Sensitized Solar Cells Containing Metal Oxides in Nanotube Form

Example 1-1

(1) Fabrication of Semiconductor Electrodes

A titanium film having a diameter of 7 μm was formed on the indium doped tin oxide transparent conductor by a sputtering method. Subsequently, a titanium oxide was formed on the outer circumferential surface of the impregnated titanium film by impregnating a portion of the titanium film with an NH ₄ F aqueous solution. At this time, the concentration of the NH ₄ F aqueous solution was 0.5% by weight. Subsequently, a voltage of 20 V was applied for 30 minutes using the titanium film as an anode. Next, the anodized titanium oxide was heat-treated in air at a temperature of 450 to 500 ° C. for 30 minutes to pyrolyze and remove the residual electrolyte, thereby converting the titanium oxide crystal structure into an anatase type. As a result, a plurality of titanium oxides were obtained.

The formed titanium oxide was each shown to have a nanotube form as shown in FIG. Subsequently, the specimen was maintained at 80 ° C., and then dye adsorption was carried out in 0.3 mM [Ru (dcb) ₂ (dfo)] (CN) ₂ dye dye solution dissolved in methanol for 12 hours. Thereafter, the dye-adsorbed nanotube-type titanium oxide thick film was washed with methanol and dried at room temperature to prepare a semiconductor electrode.

(2) production of counter electrode

As the counter electrode, a Pt layer was deposited on the indium-doped tin oxide transparent conductor by using a sputter, and a counter hole was manufactured by making a minute hole using a 0.75 mm diameter drill for electrolyte injection.

(3) Junction of semiconductor electrode and counter electrode and injection of electrolyte

The two electrodes were bonded together by pressing a 60 μm-thick thermoplastic polymer film between the semiconductor electrode and the counter electrode and pressing at 100 ° C. for 9 seconds. The redox electrolyte was injected through the micropores formed in the counter electrode, and the micropores were closed using a cover glass and a thermoplastic polymer film. The redox electrolyte used was 0.62M 1,2-dimethyl-3-hexylimidazolium iodide (1,2-dimethyl-3-hexylimidazolium iodide), 0.5M 2-aminopyrimidine (2- aminopyrimidine), 0.1 M LiI and 0.05 M I ₂ dissolved in an acetonitrile solvent were used.

Examples 1-2-1-4

A dye-sensitized solar cell was manufactured in the same manner as in Example 1-1, except that a voltage of 20 V was applied for 60 minutes, 120 minutes, and 200 minutes using the titanium film as an anode.

Example 2 Fabrication of Dye-Sensitized Solar Cells Containing Metal Oxides in the Form of Bridge Nanotubes

Example 2-1

Anodized titanium oxide was prepared in the same manner as in the preparation of (1) semiconductor electrode of Example 1, and then the anodized titanium oxide was immersed in TiCl ₄ + HCl sol solution, A dye-sensitized solar cell was manufactured in the same manner as in Example 1, except that the TiO ₂ bridge was grown by heating for a time.

The formed titanium oxide was shown to each have a bridge nanotube form as shown in FIG.

Examples 2-2 to 2-4

A dye-sensitized solar cell was manufactured in the same manner as in Example 2-1, except that a voltage of 20 V was applied for 60 minutes, 120 minutes, and 200 minutes using the titanium film as an anode.

Comparative Examples 1 to 3: Dye-Sensitized Solar Cells Containing Metal Oxides in Nanoparticle Form

Comparative Example 1

Instead of the nanotube-type metal oxide of Example 1, a titanium oxide particle dispersion having a particle size of 20 to 25 nm was coated on an area of 1 cm ² on the transparent conductor using a doctor blade method, and a heat treatment firing process was performed at 450 ° C. for 30 minutes. A dye-sensitized solar cell was manufactured in the same manner as in Example 1 except that the porous titanium oxide thick film having a thickness of 2.5 μm was used.

Comparative Examples 2-3

A dye-sensitized solar cell was manufactured in the same manner as in Comparative Example 1-1, except that the thickness of the porous titanium oxide thick foil was changed to 4.2 μm and 7.3 μm, respectively.

In order to evaluate the light conversion characteristics of the dye-sensitized solar cells prepared in Examples 1 and 2 and Comparative Example 1, the short-circuit current (Jsc) according to the thickness of the titanium oxide (T) was measured and shown in FIG. 9. In addition, in the case of Comparative Examples and Examples, the titanium oxide thickness (T) and the short circuit current (Jsc) are listed as specific values in Table 1 below.

A xenon lamp (Oriel, 01193) was used as the light source, and the solar condition (AM 1.5) of the xenon lamp was a standard solar cell (Frunhofer Institute Solare Engeries systeme, Certificate No. C-ISE369, Type of material: Mono-). Si + KG filter).

Table 1

Referring to Table 1, the dye-sensitized solar cells of Examples 1-1 to 1-4 and 2-1 to 2-4 have the same thickness of titanium oxide by introducing metal oxides in the form of nanotubes and bridge nanotubes, respectively. That is, it can be seen that the current characteristic is improved with respect to the thickness of the light absorption layer. This is understood to be due to the increase in light absorption by the dye and the improvement of current due to the shortening of the transfer path of electrons generated in the dye. However, as in Comparative Examples 1 to 3, when the metal oxide in the form of nanoparticles is introduced, it can be seen that the photocurrent generation is significantly reduced due to the light loss and the electron loss caused by the metal oxide.

Example 3 Fabrication of Dye-Sensitized Solar Cells Containing Metal Oxides in the Form of Nanorods

(1) Fabrication of Semiconductor Electrodes

A titanium film having a diameter of 5 μm was formed on the indium doped tin oxide transparent conductor by a sputtering method. Subsequently, a titanium oxide was formed on the outer circumferential surface of the impregnated titanium film by impregnating a portion of the titanium film in an aqueous solution of H ₂ O ₂ + TaCl ₅ . At this time, the concentration of TaCl ₅ in a 30 wt% H ₂ O ₂ aqueous solution was ₅ mM. Subsequently, a voltage of 10 V was applied for 120 minutes using the titanium film as an anode. Next, the anodized titanium oxide was heat-treated in air at a temperature of 450 ° C. for 30 minutes to pyrolyze and remove the residual electrolyte, thereby converting the crystal structure of titanium oxide into an anatase type.

The formed metal oxides were each shown to have a nanorod shape as shown in FIGS. 10 and 11. Subsequently, after the specimen was maintained at 80 ° C., dye adsorption was performed for 0.3 hours in a 0.3 mM [Ru (dcb) ₂ (dfo)] (CN) ₂ dye dye solution dissolved in methanol. Thereafter, the dye-adsorbed nanorod titanium oxide thick film was washed with methanol and dried at room temperature to prepare a semiconductor electrode.

(2) Preparation of counter electrode

As the counter electrode, a Pt layer was deposited on the indium-doped tin oxide transparent conductor using a sputter, and a counter hole was manufactured by making a minute hole using a 0.75 mm diameter drill for electrolyte injection.

The two electrodes were bonded together by pressing a 60 μm-thick thermoplastic polymer film between the semiconductor electrode and the counter electrode at 100 ° C. for 9 seconds. The redox electrolyte was injected through the micropores formed in the counter electrode, and the micropores were closed using a cover glass and a thermoplastic polymer film. The redox electrolyte used was 0.62M 1,2-dimethyl-3-hexylimidazolium iodide (1,2-dimethyl-3-hexylimidazolium iodide), 0.5M 2-aminopyrimidine (2- aminopyrimidine), 0.1 M LiI and 0.05 M I ₂ dissolved in an acetonitrile solvent were used.

Example 4 Fabrication of Dye-Sensitized Solar Cell Comprising Metal Oxide in the Form of Bridge Nanorods

Anodized titanium oxide was prepared in the same manner as in the preparation of (1) semiconductor electrode of Example 3, and then the anodized titanium oxide was immersed in TiCl ₄ + HCl sol solution, A dye-sensitized solar cell was manufactured in the same manner as in Example 3, except that the TiO ₂ bridge was grown by heating for a time.

The formed metal oxides were each shown to have a bridge nanorod shape as shown in FIGS. 12 and 13.

Comparative Example 2: Fabrication of Dye-Sensitized Solar Cells Containing Metal Oxides in Nanoparticle Form

Instead of the nanorod-shaped metal oxide of Example 3, a titanium oxide particle dispersion having a particle size of 20 to 25 nm was applied to a 1 cm ² area on a transparent conductor using a doctor blade method, and a heat treatment firing process was performed at 450 ° C. for 30 minutes. A dye-sensitized solar cell was manufactured in the same manner as in Example 3, except that the porous titanium oxide thick film having a thickness of 15 μm was used.

The photoelectric conversion quantum efficiency of the dye-sensitized solar cells prepared in Examples 3, 4 and Comparative Example 2 was measured and shown in FIG. 14. Here, the photoelectric conversion quantum efficiency refers to the extent to which incident photons react in the visible light region to generate current. Photoelectric conversion quantum efficiency was measured using IPCE (incident photon-to-current conversion efficient, manufactured by PV Measurements) and the wavelength range was 350-800 nm.

Referring to FIG. 14, it can be seen that the dye-sensitized solar cells of Examples 3 and 4 improve photoelectric conversion quantum efficiency by introducing metal oxides in the form of nanorods and bridge nanorods, respectively. This is understood to be due to the increase in light absorption by the dye and the improvement of current due to the shortening of the transfer path of electrons generated in the dye. However, as in Comparative Example 2, when the metal oxide in the form of nanoparticles is introduced, it can be seen that the photoelectric conversion quantum efficiency is significantly low due to light loss and electron loss caused by the metal oxide.

The above embodiments are merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the invention described in the claims below.

According to the present invention, the efficiency of the dye-sensitized solar cell can be improved by shortening the electron transport path. In addition, by forming a metal oxide film, that is, a light absorption layer into a thin film, the light absorption rate of the dye can be improved. In addition, by forming the metal oxide film in-situ (in-situ) it is possible to simplify the manufacturing process of the dye-sensitized solar cell to reduce the manufacturing cost.

Claims

A semiconductor electrode comprising a first transparent substrate and a light absorption layer disposed on one surface of the first transparent substrate;

An opposite electrode disposed to face the semiconductor electrode, the counter electrode including a catalyst layer disposed to face the light absorbing layer on the second transparent substrate and the second transparent substrate; And

An electrolyte layer interposed between the semiconductor electrode and the counter electrode;

The light absorption layer has a plurality of metal oxides having at least one type selected from the group consisting of nanotubes, bridge nanotubes, nanorods having an aspect ratio of 10 to 1000, and bridge nanorods having an aspect ratio of 10 to 1000, and adsorbed thereto. Dye-sensitized solar cell comprising a dye.
The method of claim 1,

The dye-sensitized solar cell, characterized in that the plurality of metal oxides are arranged side by side in a direction perpendicular to the smooth surface of the first transparent substrate.
The method of claim 1,

The metal is a dye-sensitized solar cell, characterized in that it comprises at least one of Ti and its alloys.
The method of claim 1,

The electrolyte layer includes at least one selected from the group consisting of poly (vinylidene fluoride-co-poly (hexafluoropropylene)), polyacrylonitrile-based polymer, polyethylene oxide-based polymer, and polyalkylacrylate-based polymer. Dye-sensitized solar cell.
A method of manufacturing a dye-sensitized solar cell having a semiconductor electrode, an electrolyte layer, and a counter electrode, the production of the semiconductor electrode,

(a) preparing a transparent substrate;

(b) coating a metal on the transparent substrate;

(c) electrochemically anodizing the metal to form a plurality of metal oxides in the form of nanotubes or nanorods;

(d) heat treating the metal oxide to crystallize the particles; And

(e) manufacturing a dye-sensitized solar cell comprising adsorbing a dye to the metal oxide.
The method of claim 5,

Between step (c) and step (d), the anodized metal oxide of step (c) is immersed in a solution containing the precursor of the metal oxide and heated to have a bridge nanotube or bridge nanorod shape. Method of manufacturing a dye-sensitized solar cell, characterized in that it further comprises the step of forming a plurality of metal oxides.
The method of claim 5,

The coating of the metal may be ion plating, magnetron sputtering, chemical vapor deposition, evaporation, spin coating, thermal oxidation, computer jet printing techniques ( A method of manufacturing a dye-sensitized solar cell, characterized by a computer jet printing technique, spray pyrolysis, or photochemical deposition.
The method of claim 7, wherein

The coating of the metal is a method of manufacturing a dye-sensitized solar cell, characterized in that the metal is incident on the transparent substrate in the direction of the normal and inclined direction of the smooth surface while the transparent substrate is rotated.
The method of manufacturing a dye-sensitized solar cell according to claim 7, wherein the anodic oxidation treatment of step (c) is performed in-situ.
The method of claim 7, wherein the plurality of metal oxides are arranged side by side in a direction perpendicular to the smooth surface of the transparent substrate.
The method of claim 7, wherein the metal comprises at least one of Ti and an alloy thereof.
The method of manufacturing a dye-sensitized solar cell according to claim 11, wherein the electrolyte used in the anodic oxidation treatment of step (c) comprises hydrogen peroxide (H 2 O 2 ).
The method of manufacturing a dye-sensitized solar cell according to claim 11, wherein the electrolyte used in the anodic oxidation treatment of step (c) contains fluorine ions.
The dye-sensitized aspect of claim 12, wherein the electrolyte contains at least one ion selected from the group consisting of fluorine ion (F − ), chlorine ion (Cl − ) and sulfate ion (SO 4 2- ). Method for producing a battery.