CN101728081A - Dye-sensitized nanocrystalline titanium dioxide photo anode and preparation method and application - Google Patents

Abstract

A dye-sensitized nanocrystalline titanium dioxide photoanode, comprising a transparent conductive substrate and a coating film coated on the transparent conductive substrate, the coating film contains titanium dioxide nanoparticles, and is characterized in that there are carbon spheres on the surface of the coating film Spherical hole structure left after calcination. The invention also discloses the preparation method and application of the photoanode. Compared with the prior art, the present invention has the advantages that colloidal carbon spheres are used as a template to form a spherical hole structure in the titanium dioxide photoanode, so as to increase the propagation path of light in the titanium dioxide film, increase the scattering performance of the photoanode, and improve the The probability of light being absorbed by the titanium dioxide film improves the utilization efficiency of the photoanode to the incident light and contributes to the improvement of the photoelectric conversion efficiency of the battery.

Description

Dye-sensitized nanocrystalline titanium dioxide photoanode, preparation method and application

technical field

The invention relates to a photoanode of a dye-sensitized nanocrystalline solar cell, and also relates to a preparation method thereof. The invention also discloses the application of the photoanode in a solar cell.

Background technique

Dye-sensitized solar cells, a photovoltaic cell with a porous titanium dioxide nanostructure photoanode sensitized by carboxylic acid bipyridyl nail complexes, have brought revolutionary innovations to the development of photoelectrochemical cells, with high photoelectric conversion efficiency and far lower prices than In traditional semiconductor solar cells, the titanium dioxide nanostructured photoanode mainly includes a transparent conductive substrate and a titanium dioxide nanoparticle coating film coated thereon, and the transparent conductive substrate is often made of conductive glass. For the technical literature in this aspect, please refer to the Chinese Invention Application Publication "Preparation Method of Photoanode of Dye-Sensitized Solar Cell" (publication number: CN101339851A) with application number 200810041804.0.

As the photoanode of the dye-sensitized nanocrystalline solar cell, the titanium dioxide film plays an important role in adsorbing the dye sensitizer and effectively and rapidly transporting electrons to the external circuit. The titanium dioxide film coated solely by titanium dioxide nanoparticles has weak absorption of long-wavelength visible light, which is not conducive to improving the photoelectric conversion efficiency of the battery. Both theory and experiments have confirmed that adding large scattering particles will increase the propagation path of light in the titanium dioxide film and increase the probability of light being absorbed by the titanium dioxide film, which will help improve the photoelectric conversion efficiency of the battery.

For this reason, Tsinghua University disclosed a method of using metal compounds to modify titanium dioxide photoanodes to improve photoelectric conversion efficiency. The reference application number is 200710090556.4 Chinese invention application publication "Dye-sensitized solar cell photoanode and its preparation method" ( Publication number: CN101030607A), this application prepares _TiO2 nanoporous film on the conductive substrate, and after the surface of the film is modified with a metal compound, the dye is then adsorbed, and the surface barrier is formed and the energy level of the semiconductor is improved through the modification of the metal compound layer. , Inhibition of surface states and other different mechanisms, greatly improving the photoelectric conversion performance of the battery, and improving the photoelectric conversion efficiency of the solar cell.

Contents of the invention

The technical problem to be solved by the present invention is to provide a photoanode of a dye-sensitized nanocrystalline solar cell that can improve the photoelectric conversion efficiency of the solar cell in view of the above-mentioned technical status quo.

Another technical problem to be solved by the present invention is to provide a method for preparing a photoanode of a dye-sensitized nanocrystalline solar cell.

Another technical problem to be solved by the present invention is to provide a photoanode of a dye-sensitized nanocrystalline solar cell for application on a solar cell.

The technical solution adopted by the present invention to solve the above technical problems is: a dye-sensitized nanocrystalline titanium dioxide photoanode, comprising a transparent conductive substrate and a coating film coated on the transparent conductive substrate, the coating film contains titanium dioxide nanoparticles, It is characterized in that the surface of the coating film has a spherical hole structure left after carbon spheres are calcined.

A method for preparing a dye-sensitized nanocrystalline titanium dioxide photoanode, characterized in that it comprises the following steps:

① Preparation of colloidal carbon spheres, preparing an aqueous sugar solution with a mass percentage of 16.6% to 33.4%, putting it into an autoclave for sealing, hydroheating, rotating and separating the obtained product, washing, and drying to obtain colloidal carbon spheres;

② Prepare the mixed slurry, take the colloidal carbon spheres in step ①, dissolve them in distilled water, and disperse evenly to obtain a 0.03-0.05g/ml (optimally 0.04g/ml) colloidal carbon sphere solution with a concentration of 0.07-0.09 g/ml (the best being 0.082g/ml), the titanium dioxide nanoparticle slurry is mixed, stirred evenly, and the weight ratio of colloidal carbon spheres and titanium dioxide nanoparticles in the resulting mixed slurry is 0.05～0.2;

③ Calcination to obtain the photoanode, the above mixed slurry is evenly coated on the transparent conductive substrate to obtain a coating film, and then calcined, the carbon balls are burned during the calcination process, and many holes appear on the transparent conductive substrate.

Preferably, the thickness of the coating film in step ③ is 9-12 μm.

Preferably, the colloidal carbon spheres described in step ① have a diameter of 200-1000 nm.

The titanium dioxide nano particle slurry is prepared by a sol-gel method using titanium isopropoxide and glacial acetic acid as precursors.

Preferably, the calcination in step ③ is completed in a muffle furnace, and the calcination temperature is 400-500°C.

Application of dye-sensitized nanocrystalline titanium dioxide photoanodes in dye-sensitized nanocrystalline solar cells. After dye sensitization, the photoanode can be assembled into a dye-sensitized nanocrystalline solar cell by dropping electrolyte and adding a platinum counter electrode.

Glucose and other sugars are used as precursors to prepare colloidal carbon spheres by hydrothermal treatment. A certain amount of titanium dioxide nanoparticles and carbon spheres of different qualities are evenly doped, coated on conductive glass, and after calcination, the surface is prepared. Titanium dioxide thin film electrode with holes and greatly improved scattering ability.

Compared with the prior art, the present invention has the advantages that colloidal carbon spheres are used as a template to form a spherical hole structure in the titanium dioxide photoanode, so as to increase the propagation path of light in the titanium dioxide film, increase the scattering performance of the photoanode, and improve the The probability of light being absorbed by the titanium dioxide film improves the utilization efficiency of the photoanode to the incident light and contributes to the improvement of the photoelectric conversion efficiency of the battery. Colloidal carbon spheres are suitable for being added into titanium dioxide nanoparticle slurry as a template due to their simple preparation, environmental protection and low cost to form spherical hole structure titanium dioxide photoanodes.

Description of drawings

1 is a photomicrograph of colloidal carbon spheres in Example 1.

Figure 2 is a photomicrograph of colloidal carbon spheres in Example 2.

3 is a photomicrograph of colloidal carbon spheres in Example 3.

FIG. 4 is a photomicrograph of the photoanode obtained in Example 2.

Fig. 5 is a photomicrograph of a photoanode obtained in a comparative example.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments and accompanying drawings.

Example 1: 300nm carbon spheres (shown in FIG. 1 ) were obtained from 1M glucose for 4 hours by hydrothermal treatment at 180°C. Rotate and separate, dry in an oven at 60 ° C for 12 hours, then dissolve 0.3 g of the carbon spheres in distilled water (the concentration of the colloidal carbon sphere solution is 0.04 g/ml), and then mix with the titanium dioxide slurry prepared by the colloidal gel method after high-power ultrasound (the slurry concentration is 0.082g/ml, containing 2g of titanium dioxide nanoparticles) blended, and then stirred for 1 hour, and then coated on the conductive glass with a film thickness of about 12 μm. The conductive glass coated with the film was calcined in a muffle furnace at 450° C. for 2 hours to obtain the photoanode of the dye-sensitized nanocrystalline solar cell. The photoanode was immersed in N3 solution with a concentration of 5×10 ^-4 mol/L for 24 hours, and the photoanode was fully sensitized by the dye. Then the photoanode was docked with the platinum counter electrode, the electrolyte was dropped, and its efficiency was tested under a xenon lamp simulating the sun light source. The composition of electrolyte is 1M LiI, 0.1M I2, 0.5M 4-butylpyridine, and solvent is acetonitrile and propylene carbonate (PC) (volume ratio is 1: 1). The xenon lamp used to measure the efficiency simulates sunlight, and the light intensity is 90.4mW/cm ² (the light intensity is measured with a standard silicon photodiode). Under this light intensity, the photoelectric conversion efficiency of the cell composed of the thin film electrodes is measured to be 6%. Compared with the 5.5% efficiency of the battery obtained by simply coating the P25 nanoparticle film, it has increased by 9%.

Example 2: 500nm carbon spheres (shown in Figure 2) were obtained from 0.75M glucose for 8 hours and hydrothermally at 180°C. Rotate and separate, dry in an oven at 60 ° C for 12 hours, then dissolve 0.3 g of the carbon spheres in distilled water (the concentration of the colloidal carbon sphere solution is 0.035 g/ml), and then mix with the titanium dioxide slurry prepared by the colloidal gel method after high-power ultrasound (slurry concentration is 0.085g/ml, containing 1.8g of titanium dioxide nanoparticles), and then stirred for 1h, then coated on the conductive glass, the film thickness is about 12μm. The conductive glass coated with the film was calcined in a muffle furnace at 450° C. for 2 hours to obtain the photoanode of the dye-sensitized nanocrystalline solar cell. Many holes are left on the surface, as shown in Figure 4. The photoanode was soaked in N3 solution with a concentration of 5×10 ^-4 mol/L for 24 hours, and the photoanode was fully sensitized by the dye. Then the photoanode was docked with the platinum counter electrode, the electrolyte was dropped, and its efficiency was tested under a xenon lamp simulating the sun light source. The composition of the electrolyte is 1M LiI, 0.1M I2, 0.5M 4-butylpyridine, and the solvent is acetonitrile and propylene carbonate (PC) (volume ratio is 1:1). The xenon lamp used to measure the efficiency simulates sunlight, and the light intensity is 90.4mW/cm2 (the standard silicon photodiode measures the light intensity). Under this light intensity, the photoelectric conversion efficiency of the cell composed of the thin film electrode is measured to be 7.2%, which is higher than that of the simple The efficiency of the 5.5% cell obtained by the P25 nanoparticle coating film was increased by 31%.

Example 3: 700nm carbon spheres (shown in FIG. 3 ) were obtained from 1M glucose for 8 hours by hydrothermal treatment at 180°C. Rotate and separate, dry in an oven at 60 ° C for 12 hours, then dissolve 0.3 g of the carbon spheres in distilled water (the concentration of the colloidal carbon sphere solution is 0.045 g/ml), and mix with the titanium dioxide slurry prepared by the colloidal gel method after high-power ultrasound (slurry concentration is 0.078g/ml, containing 1.8g of titanium dioxide nanoparticles), and then stirred for 1h, then coated on the conductive glass, the film thickness is about 12μm. The conductive glass coated with the film was calcined in a muffle furnace at 450° C. for 2 hours to obtain the photoanode of the dye-sensitized nanocrystalline solar cell. The photoanode was soaked in N3 solution with a concentration of 5×10 ^-4 mol/L for 24 hours, and the photoanode was fully sensitized by the dye. Then the photoanode was docked with the platinum counter electrode, the electrolyte was dropped, and its efficiency was tested under a xenon lamp simulating the sun light source. The composition of the electrolyte is 1M LiI, 0.1M I2, 0.5M 4-butylpyridine, and the solvent is acetonitrile and propylene carbonate (PC) (volume ratio is 1:1). The xenon lamp used to measure the efficiency simulates sunlight, and the light intensity is 90.4mW/cm2 (the standard silicon photodiode measures the light intensity). Under this light intensity, the photoelectric conversion efficiency of the cell composed of the thin film electrode is measured to be 6.14%, which is higher than that of the simple The efficiency of the battery obtained by the P25 nanoparticle coating film was increased by 10.9% from 5.5%.

Example 4, 300nm carbon spheres were obtained by hydrothermal treatment at 180°C for 8 hours with 1M glucose. Rotate and separate, dry in an oven at 60 ° C for 12 hours, then dissolve 0.3 g of the carbon spheres in distilled water (the concentration of the colloidal carbon sphere solution is 0.045 g/ml), and mix with the titanium dioxide slurry prepared by the colloidal gel method after high-power ultrasound (slurry concentration is 0.078g/ml containing 1.8g of titanium dioxide nanoparticles), and then stirred for 1 hour, and then coated on the conductive glass with a film thickness of 9 μm. The conductive glass coated with the film was calcined in a muffle furnace at 450° C. for 2 hours to obtain the photoanode of the dye-sensitized nanocrystalline solar cell. The photoanode was soaked in N3 solution with a concentration of 5×10 ^-4 mol/L for 24 hours, and the photoanode was fully sensitized by the dye. Then the photoanode was docked with the platinum counter electrode, the electrolyte was dropped, and its efficiency was tested under a xenon lamp simulating the sun light source. The composition of the electrolytic solution is 1MLiI, 0.1M I2, 0.5M 4-butylpyridine, and the solvent is acetonitrile and propylene carbonate (PC) (volume ratio is 1:1). The xenon lamp used to measure the efficiency simulates sunlight, and the light intensity is 90.4mW/cm2 (the standard silicon photodiode measures the light intensity). Under this light intensity, the photoelectric conversion efficiency of the cell composed of the thin film electrode is measured to be 6.13%, which is higher than that of the simple The efficiency of the battery obtained by the P25 nanoparticle coating film was 5.5% improved by 10.8%.

Comparative example: 5 g of titanium dioxide nanoparticles with a particle size of 10 nm prepared by the sol-gel method were added with 0.4 ml of Triton. The obtained slurry was evenly coated on conductive glass with a film thickness of about 12 μm. Then, it was calcined at 450°C for 2 hours to obtain the photoanode of the dye cell, and the surface structure is shown in Fig. 5 . The photoanode was soaked in N3 solution with a concentration of 5×10 ^-4 mol/L for 24 hours, and the photoanode was fully sensitized by the dye. Connect the photoanode to the platinum counter electrode, drop in the electrolyte, and test its efficiency under a xenon lamp simulated sun light source. The composition of the electrolyte is 1M LiI, 0.1M I2, 0.5M 4-butylpyridine, and the solvent is acetonitrile and propylene carbonate (PC) (volume ratio is 1:1). The xenon lamp used to measure the efficiency simulates sunlight, and the light intensity is 90.4mW/cm2 (the standard silicon photodiode measures the light intensity). Under the light intensity, the photoelectric conversion efficiency of the cell composed of the thin film electrodes was measured to be 5.55%.

Claims (8)

1. A dye-sensitized nanocrystalline titanium dioxide photoanode, comprising a transparent conductive substrate and a film coated on the transparent conductive substrate, containing titanium dioxide nanoparticles in the film, characterized in that the surface of the film has The spherical pore structure left after carbon spheres are calcined. 2. A preparation method for a dye-sensitized nanocrystalline titanium dioxide photoanode, characterized in that it comprises the steps: ① Preparation of colloidal carbon spheres, preparing an aqueous sugar solution with a mass percentage of 16.6% to 33.4%, putting it into an autoclave for sealing, hydroheating, rotating and separating the obtained product, washing, and drying to obtain colloidal carbon spheres; ② Prepare the mixed slurry, take the colloidal carbon spheres in step ①, dissolve them in distilled water, and disperse evenly to obtain a 0.03-0.05 g/ml colloidal carbon sphere solution, and a titanium dioxide nanoparticle slurry with a concentration of 0.07-0.09 g/ml The materials are mixed and stirred evenly, and the weight ratio of colloidal carbon spheres and titanium dioxide nanoparticles in the obtained mixed slurry is 0.05 to 0.2; ③ Calcination to obtain the photoanode, the above mixed slurry is evenly coated on the transparent conductive substrate to obtain a coating film, and then calcined, the carbon balls are burned during the calcination process, and many holes appear on the transparent conductive substrate. 3. The preparation method according to claim 2, characterized in that the thickness of the coating film in step ③ is 9-12 μm. 4. The preparation method according to claim 2, characterized in that the sugar described in step 1. is sucrose or glucose, 5. The preparation method according to claim 2, characterized in that the colloidal carbon spheres described in step ① have a diameter of 200-1000 nm. 6. The preparation method according to claim 2, characterized in that the titanium dioxide nanoparticle slurry is prepared by a sol-gel method using titanium isopropoxide and glacial acetic acid as precursors. 7. The preparation method according to claim 2, characterized in that the calcination in the step ③ is completed in a muffle furnace, and the calcination temperature is 400-500°C. 8. The application of the dye-sensitized nanocrystalline titanium dioxide photoanode described in claim 1 in dye-sensitized nanocrystalline solar cells.

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