KR101714971B1 - Metal substrate for flexible dye-sensitized solar cell and flexible dye-sensitized solar cell using the same - Google Patents

Abstract

A counter electrode for a flexible dye-sensitized solar cell according to an embodiment of the present disclosure includes a conductive substrate and a coating layer formed on the conductive substrate, wherein the conductive substrate includes one selected from the group consisting of carbon steel and stainless steel do. Since the counter electrode includes the conductive substrate and the coating layer, a low cost counter electrode material can be used without deteriorating the solar cell efficiency.

Description

TECHNICAL FIELD [0001] The present invention relates to a dye-sensitized solar cell, and more particularly, to a dye-sensitized solar cell using a dye-sensitized solar cell,

This disclosure relates to a counter electrode for a flexible dye-sensitized solar cell and a flexible dye-sensitized solar cell.

The dye-sensitized solar cell is a device that applies the principle of photosynthesis of plants. It produces electricity by using specific dyes and electrolytes that emit electrons when exposed to sunlight. It uses photosensitive dyes for solar absorption, wide energy A metal oxide particle having a bandgap, an electrolyte layer serving as a p-type semiconductor, a counter electrode, and a transparent electrode for transmitting sunlight.

When the dye-sensitized solar cell absorbs light, the photosensitive dye particles are excited to generate electrons (oxidation), and the generated electrons move to the conduction band of the metal oxide, And flows into the circuit to transmit electric energy. At the same time, the oxidized dye particles are returned to the original ground state by being supplied with electrons from the reducing material (I ^- ) of the redox mediator in the electrolyte layer. The redox mediator, which provides electrons for this reaction and is converted to an oxidized form (I ^{3 -} ), is returned to the reduced form (I ^- ) with the aid of a counter electrode acting as an electrocatalyst.

As a means for achieving high efficiency of such a dye-sensitized solar cell, a counter electrode which is excellent in chemical resistance to an iodine-based electrolyte and capable of rapidly promoting the reduction reaction of the redox mediator present in the electrolyte is required have.

Particularly, titanium is very useful as a material for a counter electrode because of its high corrosion resistance and conductivity and excellent catalytic properties. However, titanium has a disadvantage of low cost because of high price of raw materials.

Further, a structure of a flexible dye-sensitized solar cell that does not deteriorate the solar cell efficiency even when used outdoors for a long time is proposed.

When a polymer film is used as the flexible transparent substrate, problems such as moisture penetration from the outside and deterioration due to ultraviolet rays may occur.

In order to solve such a problem, there is a need for a counter electrode material excellent in low-cost chemical resistance and a technique capable of securing the long life of the solar cell without deteriorating the solar cell efficiency.

Patent Document 1 of the following prior art document relates to a flexible optical electrode, a manufacturing method thereof, and a dye-sensitized solar cell using the same.

Korean Patent Publication No. 2012-0084529

According to one embodiment of the present disclosure, there is provided a counter electrode for a flexible dye-sensitized solar cell and a flexible dye-sensitized solar cell.

The counter electrode for a flexible dye-sensitized solar cell according to an embodiment of the present disclosure includes a conductive substrate and a coating layer formed on the conductive substrate, and the conductive substrate may be one selected from the group consisting of carbon steel and stainless steel.

A flexible dye-sensitized solar cell according to an embodiment of the present disclosure includes a flexible transparent substrate, a transparent electrode layer formed on the transparent substrate, an oxide semiconductor layer formed on the transparent electrode layer, and an oxide semiconductor layer Wherein the counter electrode includes a conductive substrate and a coating layer formed on the conductive substrate, and the conductive substrate may be one selected from the group consisting of carbon steel and stainless steel.

According to one embodiment of the present disclosure, a counter electrode for a flexible dye-sensitized solar cell and a flexible dye-sensitized solar cell capable of using a low-cost material for a counter electrode without deteriorating the solar cell efficiency, Battery can be provided.

1 is a schematic cross-sectional view of a flexible dye-sensitized solar cell according to an embodiment of the present disclosure;
2 is a graph showing voltage-current characteristics of a flexible dye-sensitized solar cell using a counter electrode according to an embodiment of the present disclosure.

Preferred embodiments of the present disclosure will now be described with reference to the accompanying drawings.

However, the embodiments of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art.

The embodiments of the present disclosure can be modified into various other forms, and the scope of the present disclosure is not limited to the embodiments described below.

The shape and size of elements in the drawings may be exaggerated for clarity.

In the drawings, like reference numerals are used to designate like elements that are functionally equivalent to the same reference numerals in the drawings.

In addition, to include an element throughout the specification does not exclude other elements unless specifically stated otherwise, but may include other elements.

Hereinafter, a counter electrode for a flexible dye-sensitized solar cell according to the present disclosure will be described in detail.

A counter electrode for a flexible dye-sensitized solar cell according to an embodiment of the present disclosure includes a conductive substrate; And a coating layer formed on the conductive substrate, wherein the conductive substrate is one selected from the group consisting of carbon steel and stainless steel.

As a conductive substrate of a counter electrode for a dye-sensitized solar cell, any substrate used in the related art can be used as long as it is suitable for a continuous process by a roll-to-roll method. For example, there are stainless steel, carbon steel, Fe-Ni alloy, Fe-Cr alloy, Fe-Cu alloy, aluminum alloy, titanium alloy, thin film glass, polyimide and polyethylene terephthalate .

Conventionally, a conductive substrate containing a titanium-based metal having high resistance to iodine was used. Titanium-based metals have the advantage of high chemical resistance, but they are weak in the cost competitiveness of solar cells because they are expensive.

According to one embodiment of the present disclosure, the counter electrode for a flexible dye-sensitized solar cell comprises a conductive substrate that is one selected from the group consisting of carbon steel and stainless steel.

If the conductive substrate is made of carbon steel or stainless steel, the material for the counter electrode can be used at a low cost without deteriorating the efficiency of the solar cell, and the cost competitiveness of the solar cell can be secured.

The coating layer may include a material having excellent chemical resistance to iodine.

The coating layer may be fluorine-doped tin oxide (FTO) or fluorine zinc oxide (FZO).

If the coating layer is formed on the conductive substrate, the chemical resistance to iodine can be secured, and the efficiency and productivity of the solar cell can be secured.

The coating layer may be formed using a selected one of deposition and sputtering methods.

The coating layer may have a thickness of 400 nm or more and 1 μm or less.

When the thickness of the coating layer is 400 nm or less, the electrolyte layer may permeate the coating layer, or the conductive substrate having a certain roughness may not be sufficiently coated. As a result, a region where the coating is sufficiently formed in the conductive substrate is generated, and the region can be corroded by the iodine contained in the electrolyte layer, thereby reducing the efficiency of the solar cell.

If the thickness of the coating layer is 1 μm or more, the process time of the coating may be prolonged and the productivity of the solar cell may be lowered.

Hereinafter, the flexible dye-sensitized solar cell according to the present disclosure will be described in detail.

1 is a schematic cross-sectional view of a flexible dye-sensitized solar cell according to an embodiment of the present disclosure;

Referring to FIG. 1, a flexible dye-sensitized solar cell 100 according to an embodiment of the present disclosure includes a flexible transparent substrate 131; A transparent electrode layer 132 formed on the transparent substrate 131; An oxide semiconductor layer 120 formed on the transparent electrode layer 132; A counter electrode 110 disposed opposite to the oxide semiconductor layer 120 so as to face each other with a predetermined gap therebetween; And an electrolyte layer 140 filling a space between the oxide semiconductor layer 120 and the counter electrode 110. The counter electrode 110 includes a conductive substrate 111 and a conductive substrate 111, And the conductive substrate 111 is one kind selected from the group consisting of carbon steel and stainless steel.

Conventional flexible dye-sensitized solar cells use a polymer film as a transparent substrate. If the polymer film is used as a transparent substrate, problems such as external moisture penetration and ultraviolet ray deterioration may occur.

According to one embodiment of the present disclosure, the flexible transparent substrate 131 may be a thin glass substrate.

If the transparent substrate 131 is a thin glass substrate, a flexible dye-sensitized solar cell can be fabricated. In addition, the thin glass substrate can block moisture from the outside, deterioration due to ultraviolet rays can be prevented, and the lifetime of the solar cell can be prolonged.

The thickness of the transparent substrate 131 may range from 30 탆 to 100 탆.

If the thickness of the transparent substrate is less than 30 占 퐉, it can be easily broken by external force. If the thickness of the transparent substrate exceeds 100 占 퐉, flexibility of the substrate may be deteriorated.

The transparent electrode layer 131 may be formed using a high electrical conductivity material, for example indium tin oxide (ITO; indium Tin Oxide), tin oxide with fluorine-doped (FTO; F-doped SnO _2), (ZnO), and antimony tin oxide (ATO), but the present invention is not limited thereto.

The oxide semiconductor layer 120 may include metal oxide particles 121 and dye particles 122.

The dye particles 122 may be adsorbed on the surface of the metal oxide particles 121.

The metal oxide particles 121 may have various shapes of nano-sized particles, for example, a nanotube, a nanorod, a nanosphere, a nanofiber, or a nanobelt. But is not limited thereto.

The metal oxide particles 121 may be formed of, for example, titanium dioxide (TiO ₂ ), tin dioxide (SnO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), tungsten oxide (WO ₃ ), niobium oxide ₂ O ₅ ) and titanium oxide strontium (TiSrO ₃ ).

The dye particles 122 may be adsorbed on the surface of the metal oxide particles 121.

The dye particles 122 are capable of stable chemical bonding with the surface of the metal oxide particles 121 and have thermal and optical stability.

The dye particles 122 may be formed of a material selected from the group consisting of aluminum, platinum, palladium, europium, lead, iridium, ruthenium, And the like.

The counter electrode 110 is opposed to the oxide semiconductor layer 120 with a predetermined gap therebetween.

The counter electrode 110 includes a conductive substrate 111 and a coating layer 112 formed on the conductive substrate 111.

The conductive substrate 111 is one kind selected from the group consisting of carbon steel and stainless steel.

If the conductive substrate is made of carbon steel or stainless steel, the material for the counter electrode can be used at a low cost without deteriorating the efficiency of the solar cell, thereby ensuring cost competitiveness of the solar cell.

The coating layer 112 may include a material having excellent chemical resistance to iodine.

The coating layer 112 may be one selected from the group consisting of fluorine-doped tin oxide (FTO) and fluorine zinc oxide (FZO).

When the coating layer 112 is formed on the conductive substrate, the chemical resistance to iodine can be secured, and the efficiency and productivity of the solar cell can be secured.

The coating layer 112 may be formed using one of deposition and sputtering methods.

The coating layer 112 may have a thickness of 400 nm or more and 1 μm or less.

When the thickness of the coating layer is 400 nm or less, the electrolyte layer may permeate the coating layer, or the conductive substrate having a certain roughness may not be sufficiently coated. As a result, a region where the coating is sufficiently formed in the conductive substrate is generated, and the region can be corroded by the iodine contained in the electrolyte layer, thereby reducing the efficiency of the solar cell.

If the thickness of the coating layer is 1 μm or more, the process time of the coating may be prolonged and the productivity of the solar cell may be lowered.

The electrolyte layer 140 fills a space between the oxide semiconductor layer 120 and the counter electrode 110.

The electrolyte layer 140 may receive electrons from the counter electrode by oxidation-reduction and transfer the electrons to the dye particles.

The electrolyte layer 140 may include an iodine-based redox electrolyte (redox iodide electrolyte), for example, iodine (I) system, a bromine (Br) based, cobalt (Co) based, thiocyanate (SCN ^-) And an electrolyte containing a selenium cyanide (SeCN ^- ) system.

When the electrolyte layer is a liquid, there is a restriction that it is only possible to manufacture a sheet type batch type, and solvent volatility and sublimation of iodine are problematic for long-term high-temperature stability, and the volatility and sublimation property Complete sealing becomes a problem.

The electrolyte layer 140 may be a semi-solid electrolyte.

The semi-solid electrolyte may be organic polymer or inorganic hole transfer materials (HTM).

The electrolyte layer may be formed using a spin coating method, but is not limited thereto.

If the electrolyte layer 140 is a semi-solid electrolyte, the thin film glass substrate on which the oxide semiconductor layer is formed is continuously adhered to form a flexible dye-sensitized solar cell. As a result, the mass productivity of the flexible dye-sensitized solar cell can be secured.

When the electrolyte layer is a semi-solid electrolyte, the shape of the dye-sensitized solar cell can be changed during fabrication to provide flexibility, and the thin film of the electrolyte layer can be manufactured. In addition, it can maintain a stable performance under thermal stress or light penetration as compared with a liquid electrolyte, and can contribute to improvement of long-term stability.

The flexible dye-sensitized solar cell 100 according to an embodiment of the present invention includes a flexible transparent electrode 130 on which the oxide semiconductor layer 120 is formed, The counter electrode 110 on which the electrolyte layer 140 is formed may be disposed so as to be covered with the polymer adhesive 150.

FIG. 2 is a graph showing voltage-current characteristics of a flexible dye-sensitized solar cell using a counter electrode according to an embodiment of the present disclosure.

FIG. 2 shows graphs of Comparative Example (A), Example 1 (B) and Example 2 (C) obtained under the condition of AM 1.5 G 1 Sun.

Table 1 shows the short circuit current (Isc), the open circuit voltage (Voc) and the photoelectric efficiency (?) Of the flexible dye-sensitized solar cell of each of Comparative Example, Example 1 and Example 2, ) And a fill factor (FF).

The above 1 Sun condition satisfies solar cell temperature of 25 캜 and light intensity AM 1.5G 100 mW / cm ² .

 The short circuit current Isc is the maximum current density that can be obtained in the solar cell when no voltage is generated in the solar cell.

The open-circuit voltage Voc is a potential difference when no additional current is injected into both electrodes of the solar cell.

The filling factor FF is a value obtained by dividing the maximum output Pmax of the solar cell by the product of the open-circuit voltage Voc and the short-circuit current Isc and is a main measure of the performance of the battery.

In the comparative example, titanium was used as the conductive substrate of the counter electrode, and no coating layer was formed.

In the above embodiment, carbon steel was used as a conductive substrate of the state electrode, and a coating layer was formed. The above Examples 1 and 2 have coating thicknesses of 100 nm and 400 nm, respectively.

Conductive substrate The thickness of the coating layer Isc
(A) Voc
(V) Pmax
(W) FF
(%) η
(%) Comparative Example  titanium - 2.676 2.976 4.74 60.0 5.81 Example 1 Carbon steel 100 nm 2.679 2.999 4.22 52.59 5.16 Example 2 Carbon steel 400 nm 2.665 3.027 5.185 64.28 6.33

Referring to FIG. 2 and Table 1, Comparative Example (A) and Example 1 (B) have lower open-circuit voltage (Voc) and lower filling factor (FF) than Example 2 (C) It was confirmed that the efficiency was low.

Comparing the comparative example and the example, it can be seen that the efficiency of Example 1 is slightly lower than that of the comparative example, but the efficiency of Example 2 is improved as compared with the comparative example.

Therefore, it was confirmed that the thickness of the coating layer was 400 nm or more and 1 μm or less, thereby ensuring a higher solar cell efficiency than the comparative example.

When the thickness of the coating layer is 400 nm or less, the electrolyte layer may permeate the coating layer, or the conductive substrate having a certain roughness may not be sufficiently coated. As a result, a region where the coating is sufficiently formed in the conductive substrate is generated, and the region can be corroded by the iodine contained in the electrolyte layer, thereby reducing the efficiency of the solar cell.

If the thickness of the coating layer is 1 μm or more, the process time of the coating may be prolonged and the productivity of the solar cell may be lowered.

It can be confirmed that the counter electrode of the flexible dye-sensitized solar cell according to the present embodiment has a higher efficiency than the counter electrode including titanium of the comparative example, since it includes a conductive substrate and a coating layer containing carbon steel.

100: Flexible dye-sensitized solar cell
110: counter electrode
111: conductive substrate
112: coating layer
120: oxide semiconductor layer
121: metal oxide particle
122: Dye particle
130: transparent electrode
131: transparent electrode layer
132: Flexible transparent substrate
140: electrolyte layer
150: Polymer adhesive

Claims (7)

A conductive substrate selected from the group consisting of carbon steel and stainless steel; And
And a coating layer formed on the conductive substrate and made of fluorine-doped tin oxide (FTO).
The method according to claim 1,
Wherein the thickness of the coating layer is 400 nm or more and 1 占 퐉 or less.
Flexible transparent substrate;
A transparent electrode layer formed on the transparent substrate;
An oxide semiconductor layer formed on the transparent electrode layer;
A counter electrode disposed opposite to the oxide semiconductor layer so as to face each other with a predetermined gap therebetween; And
And an electrolyte layer filling a space between the oxide semiconductor layer and the counter electrode,
Wherein the counter electrode includes a conductive substrate that is one selected from the group consisting of carbon steel and stainless steel, and a coating layer formed on the conductive substrate and made of fluorine-doped tin oxide (FTO)
Wherein the coating layer is disposed in contact with the electrolyte layer.
The method of claim 3,
Wherein the transparent substrate is a thin glass substrate.
5. The method of claim 4,
Wherein the thickness of the transparent substrate is 30 占 퐉 to 100 占 퐉.
The method of claim 3,
Wherein the thickness of the coating layer is 400 nm or more and 1 占 퐉 or less.
The method of claim 3,
Wherein the electrolyte is a semi-solid electrolyte.

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