CN101794670B - Preparation method of photo anode of dye-sensitized solar cell with optical gradient - Google Patents

Abstract

The invention relates to a preparation method of an optical gradient dye-sensitized solar cell photoanode, comprising: (1) taking inorganic titanium salt as a precursor, adding sodium hydroxide or ammonia water to cause precipitation, and washing the precipitation with water to obtain a gel solid, degummed it to obtain a light yellow transparent solution, diluted the obtained solution, and hydrothermally treated to obtain a transparent anatase phase TiO sol; ( ₂ ) deposited on a conductive substrate by spin coating, dipping or casting One layer of TiO ₂ dense layer; (3) deposit a layer of porous TiO ₂ film on the TiO ₂ dense layer by screen printing, scraping or spraying; (4) calcining the film with two structures to form a Photoanode. The sol used to prepare the transparent dense layer in the present invention does not contain any organic matter and other impurities, does not need to be sintered at high temperature, and the barrier layer formed between the conductive layer and the porous film prevents the electrolyte from corroding the substrate, and has a good application prospect .

Description

A kind of preparation method of dye-sensitized solar cell photoanode with optical gradient

technical field

The invention belongs to the field of dye-sensitized solar cell photoanode manufacture, and in particular relates to a preparation method of a dye-sensitized solar cell photoanode with an optical gradient.

Background technique

等制备了一种类似于植物光合作用原理的新型太阳能电池，称为染料敏化纳米晶太阳能电池(DSSCs)。由于其成本低、制备工艺简单、光电转化效率较高，引起科研工作者对低成本光伏电池的广泛关注。year 1991,

prepared a new type of solar cell similar to the principle of plant photosynthesis, called dye-sensitized nanocrystalline solar cells (DSSCs). Due to its low cost, simple preparation process, and high photoelectric conversion efficiency, researchers have paid extensive attention to low-cost photovoltaic cells.

Dye-sensitized solar cells are mainly composed of conductive glass, porous nano-titanium oxide film adsorbing monolayer dye, platinum-coated conductive glass and electrolyte. Different from traditional silicon-based solar cells, dye-sensitized solar cells convert light energy into electrical energy by virtue of the strong absorption of light by dyes, and the absorption and transport of electrons are carried out separately. As the core component of dye-sensitized solar cells, the photoanode has always been the focus of researchers' research, including the influence of different nanostructures on the photoelectric performance of cells. The common problem of the photoanode prepared by the powder coating method is that the bonding force with the conductive glass substrate is not strong, the porous film is easy to fall off from the conductive glass surface, and the electrolyte is easy to directly contact with the conductive glass, which not only affects the export of photogenerated electrons , which increases the probability of photogenerated electrons recombining with I ₃ ^- in the electrolyte. Moreover, the electrolyte will corrode the conductive substrate, seriously affecting the photoelectric conversion efficiency and stability of the battery, and hindering the commercial application of the battery.

Usually 40mm TiCl ₄ aqueous solution is used to treat conductive glass to prepare a layer of dense nano-titanium oxide film to reduce the recombination of back electrons and electrolytes, and at the same time prevent the electrolyte from corroding the substrate, and ultimately improve the photocurrent of the battery. The problem with this method is that TiCl ₄ , as a substance that is easily hydrolyzed, has a certain corrosion on the conductive glass itself, and releases acidic substances after heat treatment. And Cl ^- is introduced in the battery preparation process.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a photoanode of a dye-sensitized solar cell with an optical gradient. The sol prepared by the present invention is close to neutral, does not contain any organic matter and other impurities, does not need to be sintered at high temperature, and the barrier layer formed between the conductive layer and the porous film prevents the electrolyte from corroding the substrate, and finally improves The photocurrent of the battery has a good application prospect.

A preparation method of a dye-sensitized solar cell photoanode with an optical gradient of the present invention comprises: (1) using 0.4-1M inorganic titanium salt as a precursor, adding 0.1-4M sodium hydroxide or Ammonia water makes it precipitate, and the precipitate is washed 4 to 5 times to neutrality to obtain a gel-like solid, which is degummed for 0.5 to 5 hours to obtain a light yellow transparent solution, which is diluted by 1 to 5 times, and diluted with 100 After hydrothermal treatment at ~200°C for 2-50 hours, a transparent anatase phase TiO _sol with a concentration of 0.1-5wt% is formed;

(2) Deposit _{a layer} of anatase phase nanocrystalline TiO on the conductive substrate by spin coating, immersion pulling or casting method Dense layer;

(3) Deposit a layer of porous _TiO2 film on the _TiO2 dense layer by screen printing, scraping or spraying method;

(4) calcining the film with two structures at 400-550° C. for 15-120 minutes to form a photoanode with optical gradient.

The inorganic titanium salt in the step (1) is Ti(SO ₄ ) ₂ , TiOSO ₄ , Ti(NO ₃ ) ₄ or TiCl ₄ .

The degumming method in the step (1) is to disperse the gel-like solid in HNO ₃ or H ₂ O ₂ at a ratio of 1 g: 1-10 ml.

The conductive substrate in the step (2) is fluorine-doped SnO ₂ conductive glass (SnO ₂ :F) referred to as FTO or indium tin oxide conductive glass referred to as ITO conductive glass.

The spin coating process in the step (2) is to drop the _TiO2 sol onto the conductive base fixed on the homogenizer, and to homogenize the glue for 10 to 1000 seconds at the speed of the homogenizer at 50-2000 rpm. The TiO ₂ dense layer is dried naturally or in an oven for 0.1 to 10 hours at a drying temperature of 25 to 100° C., and the above operation is repeated 1 to 50 times.

The dipping and pulling process in the step (2) is to put the conductive substrate into the TiO sol, dip for 1 to 100 minutes, dry _the TiO dense layer naturally or in an oven for 0.1 to 10 hours, and the drying temperature is ₂₅ ~100°C, repeat the above operation 1 to 10 times.

The thickness of the dense layer of anatase phase nano-crystal TiO ₂ in the step (2) is 0.1-5 microns.

The thickness of the porous _TiO2 film in the step (3) is 5-20 microns.

The _TiO2 thin film on the optical gradient dye-sensitized solar cell photoanode base material of the present invention is composed of two parts, one layer is a transparent _TiO2 nano-crystal dense layer, and the other layer is a porous titanium dioxide layer. Using highly dispersed anatase phase TiO ₂ sol as raw material, a transparent dense layer of titanium dioxide nanocrystals is formed on a conductive substrate by spin coating, casting or dipping and pulling, with a thickness of 0.1 to 5 microns and a thickness of 25 to 80 Keep for 0.1-10 hours under the condition of ℃; then deposit a layer of porous titanium oxide film with a certain thickness on the dense layer of nanocrystalline _TiO2 by screen printing, scraping, spraying and other methods; and finally obtain the dye with optical gradient Sensitized solar cell photoanode.

The invention adopts highly dispersed transparent _TiO2 sol as raw material to prepare a dye-sensitized solar cell photoanode with optical gradient. A layer of dense transparent anatase phase nanocrystalline titanium oxide film is firstly prepared at low temperature, then a layer of porous titanium dioxide film is deposited, and finally a photoanode is formed through heat treatment. The advantage of this method is that the sol is close to neutral, does not contain any organic matter and other impurities, and does not require high-temperature sintering. The morphology of the sol particles is rod-shaped, and the particle size distribution is uniform. The use of this new optical gradient dye-sensitized solar cell photoanode first forms a barrier layer between the conductive layer and the porous film, which isolates the direct contact between the electrolyte and the conductive glass, and reduces the photogenerated electrons and the I ₃ in the electrolyte. ^- Odds of compounding. The test of the IV characteristic curve of the battery shows that the photoelectric current of the battery prepared with this photoanode is greatly improved.

Beneficial effect

(1) Using the inorganic titanium source as the precursor, without adding any surfactant, the transparent anatase phase titanium oxide hydrosol was synthesized by the method of thermal crystallization of precipitation solution glue, since it is already an anatase phase, so Higher calcination temperatures are no longer required for crystallization. Moreover, the sol does not release harmful substances during heat treatment, and does not leave Cl ^- . By depositing a layer of dense titanium oxide film on the surface of FTO conductive glass, it not only reduces the recombination of photogenerated electrons on the conductive glass substrate and I ₃ ^- in the electrolyte, but also prevents the electrolyte from corroding the conductive glass.

(2) Compared with TiCl ₄ pretreatment, the thin film with optical gradient formed by the dense layer prepared by using sol has higher short-circuit current and open-circuit voltage.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of anatase phase sol;

Fig. 2 is the comparison diagram of the transmittance of the transparent dense layer prepared by the spin coating method and the empty conductive glass;

Fig. 3 is the schematic diagram of the structure of the photoanode of the optical gradient dye-sensitized solar cell;

Fig. 4 is the SEM surface topography diagram of the dense layer of the optical gradient dye-sensitized solar cell photoanode;

Fig. 5 is the SEM surface topography diagram of the porous layer of the optical gradient dye-sensitized solar cell photoanode;

Fig. 6 is the SEM sectional view of the porous layer of the photoanode of the optical gradient dye-sensitized solar cell;

Figure 7 shows the photovoltaic curves of dye-sensitized solar cells prepared with photoanodes with different structures.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Example 1

After the 1M titanium sulfate solution was heated to 60°C, 4M sodium hydroxide solution was added dropwise to neutralize until the pH value was approximately equal to 7, and a white precipitate was obtained, which was washed repeatedly with distilled water to obtain a gel-like solid. Take 80 grams of wet precipitate (containing about 12 grams of titanium dioxide) and disperse it in 100 milliliters of 30% hydrogen peroxide, and degumming at 60° C. for 2 hours to obtain a light yellow transparent solution. Take 10 ml of the transparent solution, dilute it to 40 ml, add it to a hydrothermal kettle, and take it out after 120°C hydrothermal treatment for 12 hours to form a transparent sol. Get the powder that 20 milliliters of sol vacuum dryings obtains and carry out XRD analysis, X-ray diffraction (XRD) result shows that titanium dioxide wherein is anatase phase, as shown in Figure 1, can find out to be pure anatase phase, grain size 7-8 nanometers. Prepare 50 ml of titanium dioxide sol with a concentration of 0.1 wt%, and place it in a 100 ml empty glass beaker. After cleaning the FTO conductive glass, soak it in the titanium dioxide sol for 10 minutes, then take out the conductive glass from the beaker and put it in an oven, dry it at 50°C for 30 minutes, repeat the above operation twice, and form a dense and transparent layer on the conductive glass. Anatase phase nanocrystalline layer. The transmittance of the impregnated conductive glass does not change significantly. The microscopic morphology of the surface of the nanocrystalline layer is shown in Figure 4. It can be seen that the surface of the dense layer is smooth and the sol particles are closely packed together. Then, a titanium oxide film with a thickness of 8 um was deposited on the dense layer by screen printing. Finally, the composite film was calcined at 500° C. for 30 minutes to form a photoanode of a dye-sensitized solar cell with an optical gradient. The structural schematic diagram of the photoanode of the dye-sensitized solar cell with optical gradient is shown in Fig. 3, from bottom to top there are conductive layer, dense layer and porous thin film layer.

Example 2

After heating the 1M titanium sulfate solution to 60°C, add 4M ammonia solution dropwise to the 1M titanium sulfate solution, and neutralize until the pH value is approximately equal to 7 to obtain a white precipitate, which is washed repeatedly with distilled water to obtain a gel-like solid. Take the wet precipitate 80 grams (converted into titanium dioxide is 12 grams) is dispersed in 300 milliliters of 30% hydrogen peroxide, degummed at 60 ℃ for 1 hour, obtains light yellow transparent solution, gets this transparent solution 20 milliliters, dilutes to 40 milliliters, adds to Hydrothermal kettle, 180 degrees hydrothermal treatment for 12 hours, take out to form a transparent sol. Prepare 50 milliliters of titanium dioxide sol with a concentration of 1 wt%, place it in a 100 milliliter glass beaker, and set aside. After cleaning the FTO conductive glass, soak it in the titanium dioxide sol for 30 minutes, then take it out and dry it at room temperature for 30 minutes, and repeat the above operation twice. After impregnation, the transmittance of the photoanode does not change significantly, but is still transparent. As shown in Figure 2, it can be seen that the transmittance basically does not change, indicating that the dense layer is transparent. Then, a titanium oxide film was prepared on the dense layer by screen printing, with a thickness of 10 μm, and the prepared composite film was sintered at 500° C. for 30 minutes. The microstructure of the porous film is shown in Figure 5, showing a typical porous shape. The photovoltaic performance of different structures after the battery is assembled is shown in Figure 7. It can be seen that the photocurrent density of the dye-sensitized solar cell prepared by the traditional photoanode is the smallest, and the current density of the photoanode treated with titanium tetrachloride is second. The photocurrent density of dye-sensitized solar cells prepared by gradient photoanode is the highest.

Example 3

After heating the 0.85M titanium sulfate solution to 70°C, add 4M sodium hydroxide solution dropwise to the 0.85M titanium sulfate solution, neutralize until the pH value is approximately equal to 7, and obtain a white precipitate, which is washed repeatedly with distilled water to obtain a gel-like solid , get 80 grams of wet precipitation (converted into titanium dioxide to be 12 grams) and disperse it in 200 milliliters of 30% hydrogen peroxide, obtain light yellow transparent solution, get this transparent solution 30 milliliters, dilute to 70 milliliters, join in hydrothermal kettle, After 24 hours of hydrothermal treatment at 150 degrees, it was taken out to form a transparent sol. Prepare 50 ml of titanium dioxide sol with a concentration of 2wt%, place it in a 100 ml glass beaker, and set aside. After cleaning the ITO conductive glass, soak it in the titanium dioxide sol for 50 minutes, then take it out and dry it in an oven for 30 minutes at 80°C. After impregnation, the transmittance of the photoanode does not change significantly, and it is still transparent. Then, a titanium oxide film was prepared on the dense layer by screen printing, with a thickness of 12 um, and the prepared composite film was sintered at 400° C. for 30 minutes. The microstructure of the porous film is shown in Figure 5. It can be seen that it is a typical porous structure with loose connections between particles.

Example 4

After heating the 1M titanium sulfate solution to 60°C, add 4M ammonia solution dropwise to the 1M titanium sulfate solution, and neutralize until the pH value is approximately equal to 7 to obtain a white precipitate, which is washed repeatedly with distilled water to obtain a gel-like solid. Take the wet precipitate 80 grams (converted into 12 grams of titanium dioxide) was dispersed in 800 milliliters of 30% hydrogen peroxide, and degummed for 2 hours at 50° C. to obtain a light yellow transparent solution. Take 10 milliliters of this transparent solution, dilute it to 70 milliliters, and add it to Hydrothermal kettle, after 10 hours of hydrothermal treatment at 200 degrees, take it out to form a transparent sol. The preparation concentration is 5wt% titanium dioxide sol 50 milliliters, is placed in the glass beaker of 100 milliliters, standby. After the ITO conductive glass is cleaned, it is placed on the glue homogenizer, and the rotation speed is 500 revolutions per minute. The rotation time is 30 seconds. Then take it out and put it into an oven to dry for 20 minutes, the drying temperature is 50° C., repeat the above operation 4 times. The transmittance of the photoanode after spin coating does not change significantly, and it is still transparent. Then, a titanium oxide film was prepared on the dense layer by screen printing, with a thickness of 15 um, and the prepared composite film was sintered at 500° C. for 30 minutes. The schematic diagram of the photoanode structure of the dye-sensitized solar cell with optical gradient is shown in Fig. Porous titanium dioxide layer.

Claims (8)

1. A preparation method of a dye-sensitized solar cell photoanode with an optical gradient, comprising: (1) Use 0.4-1M inorganic titanium salt as the precursor, add 0.1-4M sodium hydroxide or ammonia water at 25-80°C to produce a precipitate, and the precipitate is washed 4-5 times with water until neutral, and a gel is obtained Solid, degumming at 25-80°C for 0.5-5 hours to obtain a light yellow transparent solution, diluting the resulting solution 1-5 times, and hydrothermally treating it at 100-200°C for 2-50 hours to form a concentration of 0.1-5wt% transparent anatase phase _TiO sol; (2) Deposit _a layer of anatase phase nanocrystalline TiO on the conductive substrate by spin coating, dipping or casting method, and then dry; (3) Deposit a layer of porous _TiO2 film on the _TiO2 dense layer by screen printing, scraping or spraying method; (4) calcining the film with two structures at 400-550° C. for 15-120 minutes to form a photoanode with optical gradient. 2. A method for preparing a photoanode of a dye-sensitized solar cell with an optical gradient according to claim 1, characterized in that: the inorganic titanium salt in the step (1) is Ti(SO ₄ ) ₂ , TiOSO ₄ , Ti(NO ₃ ) ₄ or TiCl ₄ . 3. the preparation method of a kind of dye-sensitized solar cell photoanode with optical gradient according to claim 1, is characterized in that: the degumming in the described step (1) refers to gelatinous solid with 1g: 1-10ml is dispersed in HNO ₃ or H ₂ O ₂ for treatment. 4. the preparation method of a kind of dye-sensitized solar cell photoanode with optical gradient according to claim 1, is characterized in that: the conductive base in described step (2) is the _SnO of doping fluorine Conductive glass ( SnO ₂ : F) referred to as FTO or indium tin oxide conductive glass referred to as ITO conductive glass. 5. the preparation method of a kind of dye-sensitized solar cell photoanode with optical gradient according to claim 1, is characterized in that: the spin-coating process in described step (2) is to drop TiO _sol onto fixed On the conductive substrate on the homogenizer, homogenize the glue for 10-1000 seconds at the speed of the homogenizer at 50-2000 rpm, dry the TiO ₂ dense layer naturally or in an oven for 0.1-10 hours, and the drying temperature is 25 ~100°C, repeat the above operation 1 to 50 times. 6. A method for preparing a photoanode of a dye-sensitized solar cell with an optical gradient according to claim 1, characterized in that: the dipping and pulling process in the step (2) is to put the conductive substrate into TiO ₂ Immerse in the sol for 1 to 100 minutes, dry the TiO ₂ dense layer naturally or in an oven for 0.1 to 10 hours at a drying temperature of 25 to 100°C, and repeat the above operation for 1 to 10 times. 7. the preparation method of a kind of dye-sensitized solar cell photoanode with optical gradient according to claim 1, is characterized in that: the anatase phase nanocrystal TiO in the described step (2) ₂ compact layer thickness is 0.1 to 5 microns. 8 . A method for preparing a photoanode of a dye-sensitized solar cell with an optical gradient according to claim 1 , wherein the thickness of the porous TiO ₂ film in the step (3) is 5-20 microns.

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