CN100407446C - A method for preparing a flexible counter electrode for a solar cell - Google Patents

Abstract

The invention relates to a method for preparing a flexible counter electrode of a dye-sensitized nanocrystalline solar cell, which belongs to the technical field of solar cells, and specifically uses a flexible body with a catalytic function as the counter electrode of a dye-sensitized nanocrystalline solar cell. The preparation method of the flexible counter electrode of the dye-sensitized nanocrystalline solar cell is to coat a catalytic layer on the surface of the selected flexible substrate by means of coating. The preparation method of the solar cell flexible counter electrode of the invention changes the rigid counter electrode into a flexible counter electrode, which lays a foundation for the flexibility of dye-sensitized nanocrystalline solar cells in the future. The flexible counter electrode of the dye-sensitized nanocrystalline solar cell of the present invention also has wide applicability, not only can be used in the dye-sensitized nanocrystalline solar cell of the gel electrolyte, but also can be used in the dye-sensitization of the liquid electrolyte and the solid electrolyte nanocrystalline solar cells. The counter electrode prepared by this method can reduce the cost and weight of the battery.

Description

A method for preparing a flexible counter electrode for a solar cell

technical field

The invention relates to a method for preparing a flexible counter electrode of a dye-sensitized nanocrystalline solar cell, which belongs to the technical field of solar cells, and specifically uses a flexible body with a catalytic function as a counter electrode of a dye-sensitized nanocrystalline solar cell.

Background technique

教授报道基于染料敏化纳米多孔TiO₂薄膜的太阳能电池的效率达到7.1％以来，由于染料敏化纳米晶太阳能电池可以克服硅太阳能电池的缺点，具有制作工艺简单、材料纯度要求不高、价格低廉等优点的原因，所以世界各国科学家对它进行了大量的研究。Since 1991 M.

Since the professor reported that the efficiency of solar cells based on dye-sensitized nanoporous _TiO2 films has reached 7.1%, since dye-sensitized nanocrystalline solar cells can overcome the shortcomings of silicon solar cells, they have simple manufacturing processes, low material purity requirements, and low prices. And other advantages, so scientists from all over the world have done a lot of research on it.

Dye-sensitized nanocrystalline solar cells use wide-bandgap semiconducting nanocrystalline films that absorb photosensitizers on the surface as working electrodes. Because nanocrystalline films have a very large specific surface area, they can absorb a large amount of photosensitizers, thereby effectively absorbing sunlight. Light. The working principle of dye-sensitized nanocrystalline solar cells: when the dye absorbs sunlight, the electrons transition from the ground state to the excited state, and the electrons in the excited state are quickly transferred to the conduction band of the semiconductor, while the holes remain in the dye, and the electrons then pass through The nano-semiconductor network diffuses to the conductive substrate and transfers to the counter electrode through the external circuit, while the dye in the oxidized state is reduced by the electrolyte in the reduced state, and the electrolyte in the oxidized state accepts electrons and is reduced under the catalysis of the counter electrode, thereby completing the transport of electrons process.

In a photoelectric conversion process of dye-sensitized nanocrystalline solar cells, the catalytic material on the counter electrode plays a catalytic role in the redox reaction of the redox pair, improving the efficiency of the redox reaction, thereby greatly improving the dye-sensitized nanocrystalline solar energy. Photoelectric performance of the battery. Traditional dye-sensitized nanocrystalline solar cell counter electrodes use conductive glass coated with catalytic materials. The use of conductive glass not only increases the cost and weight of the battery, but also brings difficulties to the flexibility of dye-sensitized nanocrystalline solar cells. Nowadays, in the process of flexible dye-sensitized nanocrystalline solar cells, the flexibility of the counter electrode is only accomplished by using flexible conductive films instead of conductive glass. However, in the preparation process of the conductive film, in order to ensure that the conductive material can be evenly plated on the surface of the flexible substrate, the flexible substrate film is required to have a certain rigidity. Therefore, the finally obtained conductive film is a conductor with a certain rigidity, and the counter electrode made of this conductive film also has a certain rigidity, which cannot achieve the purpose of complete flexibility. In addition, since the conductive layer on the surface of the conductive film has not been sintered, the strength of the conductive layer is much lower than that of the conductive layer on the surface of the conductive glass, and the adhesion between the conductive layer and the surface of the flexible substrate is also reduced. Decreased strength and adhesion will reduce the binding force between the catalytic material and the conductive layer, increase the resistance of the counter electrode, and reduce the catalytic ability of the counter electrode. No good way has been proposed for the solution of this problem.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a method for preparing a flexible counter electrode of a solar cell, which can make the counter electrode flexible without reducing the catalytic ability of the counter electrode. Its technical solutions are:

A method for preparing a flexible counter electrode of a solar cell, the specific steps are as follows:

(1) Select the base material: select the metal filament flexible body with oxidation resistance as the base material of the flexible counter electrode of the solar cell,

(2) Substrate catalytic treatment:

A electroplating solution pretreatment: heat the electroplating solution in a 40-80°C water bath for 3 minutes,

B Put the titanium mesh and the substrate into the pretreated electroplating solution at the same time, and connect the anode of the constant current power supply to the titanium mesh with a wire, and connect the cathode of the constant current power supply to the substrate,

C Pass 2-20mA direct current between the titanium mesh and the substrate, and catalyze the surface of the substrate for 2-5 minutes to form a catalytic layer on the surface of the substrate.

D Wash the catalytically treated substrate in water at 50-90°C, then dehumidify and dry,

(3) Forming: Weave the catalytically treated substrate into a counter electrode that is similar in shape to the nanocrystal film on the anode surface.

The fineness of the metal filament is less than 50 μm, and the surface area of the cut metal filament is 3.5-4 times that of the nanocrystal film on the surface of the anode.

Materials for oxidation-resistant metal filaments include nickel, zinc, tin, stainless steel and some alloy materials.

The electroplating solution is selected from plating solutions of platinum, gold, rhodium and lanthanum.

The ratio of the volume of the electroplating solution to the volume of the substrate is 10000:1.

The thickness of the catalyst layer on the surface of the substrate is 2-13 μm.

Due to the adoption of the above technical scheme, the solar cell flexible counter electrode preparation method of the present invention changes the rigid counter electrode into a flexible counter electrode, which lays the foundation for the flexibility of dye-sensitized nanocrystalline solar cells in the future. The base material is used as the base material of the counter electrode, so the cost of the dye-sensitized nanocrystalline solar cell is greatly reduced. The flexible counter electrode of the dye-sensitized nanocrystalline solar cell of the present invention is also widely applicable, not only can be used in the dye-sensitized nanocrystalline solar cell of the gel electrolyte, but also can be used in the dye-sensitized solar cell of the liquid electrolyte and the solid electrolyte. in nanocrystalline solar cells. The counter electrode prepared by this method can reduce the cost and weight of the battery.

Description of drawings:

The accompanying drawing is a schematic cross-sectional view of the flexible counter electrode in Example 1 of the present invention. In the figure, 1-nickel metal filaments in warp yarn group, 2-nickel metal filament surface catalytic layer in warp yarn group, 3-nickel metal surface catalytic layer in weft yarn group, 4-nickel metal filament in weft yarn group.

Detailed ways

The preparation method of the solar cell flexible counter electrode is as follows:

(1) Selection of substrate: select the flexible body of oxidation-resistant metal filaments with a fineness below 50 μm as the substrate of the flexible counter electrode of the solar cell. For material selection, not only anti-oxidation metal filaments, but also four other flexible materials can be selected as the substrate of the flexible counter electrode of solar cells:

1. Fabrics made of oxidation-resistant metal filaments with a fineness of 50 μm;

2. Antioxidant polymer filaments with a fineness of 50 μm;

3. Fabrics made of antioxidant polymer filaments with a fineness of 50 μm;

4. Polymer film with thickness less than 2mm;

If the fabric or film is selected as the counter electrode substrate, the fabric or film is cut into a substrate whose area size and shape are equivalent to the nanocrystal film on the surface of the anode. If metal or polymer filaments are selected as the counter electrode base material, the metal or polymer filaments whose surface area is 3.5-4 times the area of the nanocrystal film on the surface area of the anode are cut to prepare the counter electrode.

(2) Substrate catalytic treatment:

If a metal material is used to prepare the counter electrode, the method of electroplating is selected to coat a catalytic layer on the surface of the substrate. The electroplating process is as follows:

A electroplating solution pretreatment: heat the electroplating solution in a 40-80°C water bath for 3 minutes;

B put the titanium mesh and the substrate into the pretreated electroplating solution at the same time, and connect the anode of the constant current power supply to the titanium mesh with a wire, and connect the cathode of the constant current power supply to the substrate;

C. Pass 2-20mA direct current between the titanium mesh and the substrate, and catalyze the surface of the substrate for 2-5 minutes to form a catalytic layer on the surface of the substrate;

D Wash the catalytically treated substrate in water at 50-90°C for 1 min, then dehumidify and dry;

If a polymer material is used to prepare the counter electrode, it is necessary to first plate a layer of metal on the surface of the substrate by vacuum evaporation, magnetron sputtering or ion plating to make the substrate have a certain conductivity. The specific steps are as follows:

1) Put the selected substrate into the coating equipment.

2) Load the metal target to be plated into the equipment.

3) Start coating, and coat a layer of catalytic material on the surface of the base material, the thickness of the coating is about 3 μm.

Then, according to the above-mentioned electroplating process, a catalytic layer is plated on the surface of the metal-plated polymer substrate.

For the selection of polymer substrates, another simpler method can be used to complete the catalytic treatment. Directly use vacuum evaporation, magnetron sputtering, and ion plating to coat a catalytic layer on the surface of the polymer substrate, and the thickness of the catalytic layer is controlled at 2-13 μm. This method can also obtain the effect of the electroplating method.

(3) Forming: Weave the catalytically treated substrate into a counter electrode that is similar in shape to the nanocrystal film on the anode surface.

If fabric or film is used as the substrate, the flexible body after coating has a certain catalytic area and can be directly used as the counter electrode of the solar cell. If metal filaments or polymer filaments are used as the base material, due to the small catalytic area, it cannot be directly used as the counter electrode of the solar cell after coating, and it needs to be processed into an object with a certain area before it can be used as the counter electrode of the solar cell. The filament obtained in the coating film is prepared into a fabric whose size and shape remain similar to the area and size of the nanocrystal film on the surface of the anode, and then it can be used as a counter electrode of a solar cell.

In the above method, the material of the anti-oxidation metal filament or metal fabric includes nickel, zinc, tin, stainless steel and some alloy materials. Antioxidant polymer filament or film materials include polyamide polymers, polyester polymers, polyethylene polymers and polyurethane polymers.

The electroplating solution is selected to plate platinum, gold, rhodium and lanthanum.

The ratio of the volume of the electroplating solution to the volume of the substrate is 10000:1.

The thickness of the catalyst layer on the surface of the substrate is 2-13 μm.

The oxidation resistance of the substrate means that the substrate has a good ability to resist the corrosion of iodine and iodine ions. Metal or polymer filaments can be woven into woven fabrics, knitted fabrics or nonwovens.

Specific examples:

Example 1: A nickel metal filament with a fineness of 10 μm is selected as the substrate of a flexible counter electrode of a solar cell. According to the area of 1 cm ² of the nano crystal film on the surface of the anode, a 35 cm long nickel metal wire was cut to prepare the counter electrode. Place ^120cm3 of platinum-plating plating solution at 60°C and heat for 3 minutes, then put the titanium mesh and cut wire into the plating solution together, and at the same time, ensure that the titanium mesh and the substrate are not in contact together. Connect the anode of the DC power supply to the titanium mesh with a wire, and connect the cathode of the DC power supply to the nickel metal filament. Electroplate nickel metal filaments with 10mA direct current for 3 minutes, take them out and wash them in 80°C water for 1 minute, then dehumidify and dry them. After completion, a 3 μm platinum metal catalytic layer is formed on the surface of the nickel metal filament. The nickel wire with the platinum metal catalytic layer is woven into a woven fabric with an area of 1 cm ² to make a flexible metal mesh, which is used as the counter electrode of the dye-sensitized nanocrystalline solar cell.

Example 2: A woven fabric made of polyester filaments with a fineness of 20 μm is selected as the base material of the flexible counter electrode of the solar cell. According to the area of 1 cm ² of the nanocrystal film on the surface of the anode, cut 1 cm ² of polyester fabric to prepare the counter electrode. The intercepted fabric is placed in a small vacuum evaporation machine, and the platinum target is also placed on the target position of the vacuum evaporation machine. Start the machine, implement coating, and coat a catalytic layer of 3 μm on the surface of the polyester fabric. After being taken out, it can be used as the opposite electrode of the dye-sensitized nanocrystalline solar cell.

Claims (6)

1. A preparation method for a flexible counter electrode of a solar cell, the specific steps are as follows: 1) Select the base material: select the metal filament flexible body with oxidation resistance as the base material of the flexible counter electrode of the solar cell, 2) Substrate catalytic treatment: A electroplating solution pretreatment: heat the electroplating solution in a 40-80°C water bath for 3 minutes, B Put the titanium mesh and the substrate into the pretreated electroplating solution at the same time, and connect the anode of the constant current power supply to the titanium mesh with a wire, and connect the cathode of the constant current power supply to the substrate, C Pass 2-20mA direct current between the titanium mesh and the substrate, and catalyze the surface of the substrate for 2-5 minutes to form a catalytic layer on the surface of the substrate. D Wash the catalytically treated substrate in water at 50-90°C, then dehumidify and dry, 3) Forming: Weave the catalytically treated substrate into a counter electrode that is similar in shape to the nanocrystal film on the anode surface. 2. A method for preparing a flexible counter electrode for a solar cell according to claim 1, characterized in that: the fineness of the metal filament is below 50 μm, and the surface area of the intercepted metal filament is 3.5-4% of the area of the nanocrystal film on the surface of the anode. times. 3 . The method for preparing a flexible counter electrode of a solar cell according to claim 1 , wherein the material of the oxidation-resistant metal filament includes nickel, zinc, tin, and stainless steel. 4 . 4. The method for preparing a flexible counter electrode of a solar cell according to claim 1, wherein the electroplating solution is selected from plating solutions of platinum, gold, rhodium, and lanthanum. 5 . The method for preparing a flexible counter electrode of a solar cell according to claim 1 , wherein the ratio of the volume of the electroplating solution to the volume of the substrate is 10000:1. 6 . The method for preparing a flexible counter electrode of a solar cell according to claim 1 , wherein the thickness of the catalytic layer on the surface of the substrate is 2-13 μm.

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