Application of a kind of graphite-like carbon-coated rare earth-doped TiO2 composite photo-anode film

Abstract

The application relates to an application of a graphite-like carbon-coated rare earth-doped TiO2 composite photo-anode film, belonging to the technical field of photo-anodes. The graphite-like carbon-coated rare earth-doped TiO2 composite photo-anode film comprises a double-layer structure, which is a P25-TiO2 nanocrystalline layer and a graphite-like carbon-coated (Yb, Er) doped TiO2 nanoparticle layer in sequence. The (Yb, Er) doped TiO2 nanomaterial is modified through a saccharide carbon source, hydrothermal treatment and calcination, wherein TiO2 grains remain in an anatase phase, and the photoelectric conversion efficiency of a dye-sensitized solar cell is improved.

Description

Technical Field

[0001] This application belongs to the field of photoanode technology, and in particular relates to the application of a graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film. Background Technology

[0002] With economic development, people's demand for energy is increasing, but traditional fossil fuels have problems such as non-renewability and environmental pollution. People are trying to develop and utilize new energy sources to reduce dependence on fossil fuels, and solar energy is an ideal new energy source. Solar energy is a renewable and green energy source; it is abundant, free to use, requires no transportation, and causes no pollution to the environment. It creates a new lifestyle for humanity, ushering in an era of energy conservation and pollution reduction. Solar power generation has advantages such as safety and reliability, no noise, no pollution, no need for high-voltage transmission lines, short construction period, scalability, and unattended operation. The development and utilization of this renewable and green energy source can lay a solid foundation for the coordinated and sustainable development of the economy, environment, and society. Early solar cells were silicon solar cells made from monocrystalline silicon, which had strict requirements for processes and equipment, and high manufacturing costs, making large-scale adoption difficult. Dye-sensitized solar cells (DSSCs), as a new generation of solar cell products, have a cost reduction of 90% compared to silicon cells. Their manufacturing process is simple, pollution-free, and technologically advanced. They also possess the potential for high photoelectric conversion efficiency, making them highly likely to replace traditional silicon-based solar cells and become the dominant type of solar cell in the future.

[0003] A typical dye-sensitized solar cell (DSSC) mainly consists of three parts: a dye-sensitized semiconductor photoanode, a platinum counter electrode, and an electrolyte. As a crucial component of the DSSC, the performance of the photoanode significantly impacts the photoelectric conversion efficiency. The photoanode is fabricated by coating a conductive glass layer with a semiconductor thin film adsorbed with dye. This semiconductor thin film needs to adsorb the dye and transfer the electrons generated by the dye to the conductive glass.

[0004] Existing technology discloses a rare-earth-doped upconversion TiO2 nanostructure composite photoanode and its application. The composite photoanode comprises TiO2 nanosheets and (Yb,Er) co-doped TiO2 nanocrystals. First, (Yb,Er) co-doped TiO2 nanocrystals and TiO2 nanosheets are prepared separately. Then, the nanocrystals and nanosheets are added to a mixed solution of ethyl cellulose in ethanol and terpineol in ethanol, respectively, and OP emulsifier and acetylacetone are added dropwise with stirring. The resulting suspension is ultrasonicated and then heated to 75-85℃ until the ethanol completely evaporates, yielding (Yb,Er) co-doped TiO2 nanocrystal slurry and TiO2 nanosheet slurry. These slurries are then sequentially printed layer by layer onto a conductive substrate and dried to obtain a photoanode film. However, the obtained photoanode film still suffers from low photoelectric conversion efficiency.

[0005] Therefore, the application of a graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film is developed. After the graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film is prepared into a dye-sensitized solar cell, the TiO2 grains retain the anatase phase, thereby improving the photoelectric conversion efficiency of the cell. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the primary objective of this invention is to provide an application of a graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film for the fabrication of dye-sensitized solar cells, wherein the TiO2 grains retain the anatase phase, thereby improving the photoelectric conversion efficiency of the cell.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] This invention protects the application of a graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film in the preparation of dye-sensitized solar cells. The graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film includes a bilayer structure, consisting of a P25-TiO2 nanocrystalline layer and a graphite-like carbon-coated (Yb,Er) doped TiO2 nanoparticle layer.

[0009] The graphite-like carbon-coated (Yb,Er) doped TiO2 nanoparticle layer was prepared by a hydrothermal method using a carbohydrate carbon source and by calcination treatment of the (Yb,Er) doped TiO2 nanomaterials.

[0010] The temperature for the hydrothermal method using carbohydrate carbon sources is 160~190℃;

[0011] The calcination time is 1-4 hours;

[0012] The mass ratio of the (Yb,Er) doped TiO2 nanomaterial to the sugar carbon source is 2~4:3.

[0013] This invention involves graphite-like carbon coating on rare-earth (Yb, Er)-doped TiO2 nanomaterials to prepare a graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film. This effectively prevents TiO2 grain growth, maintains the anatase phase structure, and the carbon layer exhibits excellent conductivity, creating a highly efficient electron transport channel. Furthermore, the design of a bilayer structure consisting of a P25-TiO2 nanocrystalline layer and graphite-like carbon-coated (Yb, Er)-doped TiO2 nanoparticles allows for multiple scattering of incident light internally, enhancing light capture capability. This graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film is applied in dye-sensitized solar cells to improve the photoelectric conversion efficiency of the cells.

[0014] P25-TiO2 is a nanomaterial in the prior art that contains a mixed phase of anatase and rutile TiO2.

[0015] Preferably, the carbohydrate carbon source is one or both of monosaccharides or disaccharides.

[0016] Preferably, the temperature of the hydrothermal method using carbohydrate carbon sources is 170~180℃.

[0017] Preferably, the hydrothermal process using carbohydrate carbon sources takes 4-5 hours.

[0018] Preferably, the calcination temperature is 750~850℃.

[0019] Preferably, the thickness of the double-layer structure is 9~11μm.

[0020] Preferably, the preparation method of the graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film includes the following steps:

[0021] P25-TiO2 was made into a slurry, and graphite-like carbon coated (Yb,Er) doped TiO2 nanopowder was made into a slurry. The slurry was then printed onto conductive glass by screen printing and cured to form a thin film. After heating and curing, a composite photoanode thin film was obtained.

[0022] Preferably, the P25-TiO2 slurry is cured under the following conditions: standing for 10 minutes and drying at 60°C for 15 minutes.

[0023] Preferably, the curing conditions for the slurry made of graphite-like carbon-coated (Yb,Er) doped TiO2 nanopowder are: standing for 10 minutes and drying at 60°C for 24 hours.

[0024] Preferably, the heating and curing conditions are 440~460℃ and heat preservation for 30~45 minutes.

[0025] Preferably, the screen printing method involves printing each layer of the structure twice.

[0026] Specifically, the preparation method of the (Yb,Er)-doped TiO2 nanopowder includes the following steps:

[0027] Ethanol, tetrabutyl titanate, and acetylacetone were poured into a beaker and stirred to form solution A. Ethanol, deionized water, and hydrochloric acid were mixed to form solution B. Solution B was added dropwise to solution A to form a pale yellow precursor solution. Rare earth ion source was added to the pale yellow precursor solution and stirred until completely dissolved to form solution C. Solution C was heated and stirred at 50-70°C while deionized water was added dropwise until a gel was formed. The gel was freeze-dried and then calcined at 500-900°C to obtain (Yb,Er) co-doped TiO2 nanocrystals.

[0028] Specifically, the method for preparing the slurry from the graphite-like carbon-coated (Yb,Er) doped TiO2 nanopowder includes the following steps:

[0029] S1. Dissolve ethyl cellulose in ethanol and mix thoroughly to obtain solution A;

[0030] S2. Dissolve terpineol in ethanol and mix thoroughly to obtain solution B;

[0031] S3. Slowly add solution B to solution A, mix in OP emulsifier and acetylacetone, stir evenly, then add graphite carbon-coated (Yb,Er) doped TiO2 nanoparticles, mix evenly, and then use an ultrasonic water bath until it becomes viscous to obtain a graphite carbon-coated (Yb,Er) doped TiO2 nanoparticle slurry.

[0032] Preferably, the dye-sensitized solar cell comprises a photoanode, a dye sensitizer, an electrolyte, and a counter electrode prepared by the above-mentioned graphite-carbon coated rare earth-doped TiO2 composite photoanode film and conductive glass.

[0033] Preferably, the method for preparing the dye-sensitized solar cell includes the following steps:

[0034] A catalyst layer was prepared on conductive glass to serve as the counter electrode, and dried for later use. The graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode and the counter electrode prepared above were placed face to face, with a sealing layer in between, and hot-pressed at 110~130℃ to seal them, leaving a pre-reserved injection hole. Electrolyte was injected through the injection hole, and the injection hole was sealed with curing adhesive.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] This invention provides an application of a graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film for the fabrication of dye-sensitized solar cells. The graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film comprises a bilayer structure, consisting of a P25-TiO2 nanocrystalline layer and a graphite-like carbon-coated (Yb,Er)-doped TiO2 nanoparticle layer. The (Yb,Er)-doped TiO2 nanomaterials are modified using a sugar-based carbon source through hydrothermal treatment and calcination, wherein the TiO2 grains retain the anatase phase, thereby improving the photoelectric conversion efficiency of the dye-sensitized solar cell. Attached Figure Description

[0037] Figure 1 A schematic diagram of the structure of a graphite-like carbon-coated (Yb,Er) doped TiO2 nanocrystalline photoanode;

[0038] Figure 2 XRD patterns of graphite-like carbon-coated co-doped TiO2 nanoparticles (DC-TiO2), doped but uncoated TiO2 nanoparticles (D-TiO2), undoped but coated TiO2 nanoparticles (C-TiO2), and pure TiO2 samples.

[0039] Figure 3 The image shows the upconversion fluorescence spectrum of TiO2 doped with rare earth elements (Yb, Er);

[0040] Figure 4 The UV-Vis diffuse reflectance absorption spectra of photoanodes before sensitization with DC-TiO2, D-TiO2, C-TiO2, and pure TiO2 are shown.

[0041] Figure 5 The UV-Vis diffuse reflectance absorption spectra of photoanodes sensitized with DC-TiO2, D-TiO2, C-TiO2, and pure TiO2 are shown. Detailed Implementation

[0042] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0043] I. Experimental Methods

[0044] Preparation of (Yb,Er) doped TiO2 nanomaterials by sol-gel method:

[0045] (1) Using a graduated cylinder, take 95.0 mL of tetrabutyl titanate, 150.0 mL of tert-butanol and 10.0 mL of acetylacetone and pour them into a beaker. Stir well to obtain a light yellow solution A.

[0046] (2) Weigh 2.4g of ytterbium nitrate pentahydrate and 12g of erbium nitrate pentahydrate using an analytical balance, and add them to 25mL of deionized water, 78mL of tert-butanol and 0.5mL of HCl to form a clear mixed solution B;

[0047] (3) Slowly drop solution B into solution A using a dropper. After mixing and stirring for 8 minutes, a yellow gel appears on the beaker. Continue stirring until the stir bar stops rotating. Place the gel in a freezer and freeze for 24 hours. Then, freeze dry it for 72 hours. Finally, grind the dried sample to obtain rare earth element (Yb, Er) doped TiO2 powder for later use. The condensation temperature is 233.15 K and the vacuum degree is 36 MPa.

[0048] Example 1

[0049] S1. Preparation of graphite-like carbon-coated (Yb, Er) doped TiO2 powder:

[0050] (1) Weigh 3g of (Yb,Er) doped TiO2 nanomaterial and 3g of glucose, i.e., the mass ratio of (Yb,Er) doped TiO2 nanomaterial and glucose is 1:1, add them to 145mL of deionized water, stir magnetically for 30min to mix the solution evenly, and sonicate in an ultrasonic cleaner for 20min.

[0051] (2) Place the mixture from step (1) into a muffle furnace and hydrothermally react at 180°C for 4 hours;

[0052] (3) Centrifuge the precipitate obtained in step (2) at 6000 r for 10 min, then take out the sample and sonicate it in an ultrasonic cleaner for 30 s. Repeat the operation 3 times until the solution is neutral. Then freeze-dry the sample for 12 h and calcine it in a muffle furnace at 800 °C for 3 h to obtain a white powder, namely the sample of graphite carbon-coated TiO2 (DC-TiO2).

[0053] S2. Preparation of graphite-like carbon-coated (Yb, Er) doped TiO2 slurry:

[0054] (1) Weigh 0.56g of ethyl cellulose, put it into 7mL of anhydrous ethanol, and stir magnetically until homogeneous to obtain solution A;

[0055] (2) Weigh 4.10g of terpineol, add it to 6mL of anhydrous ethanol, and stir magnetically until homogeneous to obtain solution B;

[0056] (3) Slowly add solution B to solution A. During the addition process, use a magnetic stirrer to stir and mix. Then add 0.05 mL of OP emulsifier and 0.5 mL of acetylacetone. After stirring evenly, add 2 g of the above-mentioned DC-TiO2 powder and continue to stir the solution evenly. Sonicate for 13 min and stir in an 85°C water bath until it becomes viscous to obtain DC-TiO2 slurry.

[0057] S3. Screen Printing Method: The paste is applied to the conductive glass substrate using screen printing. The first layer is a uniform P25-TiO2 paste applied twice, allowed to stand for 10 minutes, and then dried at 60℃ for 15 minutes. The second layer is a DC-TiO2 paste applied twice, allowed to stand for 10 minutes, and then dried at 60℃ for 24 hours. After drying, it is calcined in a muffle furnace at 450℃ for 30 minutes, allowed to cool naturally, and then immersed in N719 dye solution. The TiO2 film is wrapped in tin foil in the dark and dried in a 50℃ humidity drying oven for 24 hours to ensure sufficient dye adsorption onto the TiO2 film. Finally, it is washed with anhydrous ethanol and dried at 50℃ for 1 hour to obtain the dye-sensitized photoanode. Each layer of the screen printing method requires two screen printing passes (2 layers), for a total of four passes (4 layers) for the double-layer structure. The thickness of each screen-printed layer is approximately 2.66 μm, and the thickness of the double-layer structure is approximately 10.64 μm.

[0058] S4. Assemble the dye-sensitized solar cell: Prepare a catalyst layer on the counter electrode (conductive glass), coat it with carbon slurry, and dry it for later use. Place the photoanode and counter electrode prepared above face to face, seal them with a sealing layer and a Surlyn film in between, and hot-press them at 120°C, leaving a pre-reserved electrolyte injection hole. Inject electrolyte through the injection hole and seal the injection hole with UV-curable adhesive.

[0059] Example 2

[0060] The experimental conditions were the same as in Example 1, except that in step S1, the mass ratio of the (Yb,Er) doped TiO2 nanopowder to glucose was 2:3.

[0061] Example 3

[0062] The experimental conditions were the same as in Example 1, except that in step S1, the mass ratio of the (Yb,Er) doped TiO2 nanopowder to glucose was 4:3.

[0063] Example 4

[0064] The experimental conditions were the same as in Example 1, except that the calcination time in step S1. (3) was 2 h.

[0065] Example 5

[0066] The experimental conditions were the same as in Example 1, except that the calcination time in step S1. (3) was 4 h.

[0067] Example 6

[0068] The experimental conditions were the same as in Example 1, except that in step S1, the carbohydrate carbon source was sucrose.

[0069] Example 7

[0070] The experimental conditions were the same as in Example 1, except that in step S1, the carbohydrate carbon source was fructose.

[0071] Example 8

[0072] The experimental conditions were the same as in Example 1, except that the temperature of the hydrothermal method for carbohydrate carbon source described in step S1. (2) was 160°C.

[0073] Example 9

[0074] The experimental conditions were the same as in Example 1, except that the temperature of the hydrothermal method using carbohydrate carbon source in step S1. (2) was 170°C.

[0075] Example 10

[0076] The experimental conditions were the same as in Example 1, except that the temperature of the hydrothermal method using carbohydrate carbon source in step S1. (2) was 190°C.

[0077] Comparative Example 1

[0078] The experimental conditions were the same as in Example 1, except that in step S1, the mass ratio of the (Yb,Er) doped TiO2 nanopowder to glucose was 1:3.

[0079] Comparative Example 2

[0080] The experimental conditions were the same as in Example 1, except that in step S1, the mass ratio of the (Yb,Er) doped TiO2 nanopowder to glucose was 5:3.

[0081] Comparative Example 3

[0082] The experimental conditions were the same as in Example 1, except that the calcination time in step S1. (3) was 0.5 h.

[0083] Comparative Example 4

[0084] The experimental conditions were the same as in Example 1, except that the calcination time in step S1. (3) was 5 h.

[0085] Comparative Example 5

[0086] The experimental conditions were the same as in Example 1, except that the temperature of the hydrothermal method for carbohydrate carbon source described in step S1. (2) was 150°C.

[0087] Comparative Example 6

[0088] The experimental conditions were the same as in Example 1, except that the temperature of the hydrothermal method for carbohydrate carbon source described in step S1. (2) was 200°C.

[0089] II. Example / Comparative Example Test Indicators:

[0090] (1) XRD: X-ray diffraction data (XRD) of DC-TiO2, D-TiO2, C-TiO2 and pure TiO2 were obtained using an X-ray diffractometer at 45 kV and 40 mA. The specific test conditions were CuKα radiation (λ = 1.5406 Å), scanning range of 2θ = 20°~80°, and scanning speed of 10° / min;

[0091] (2) Upconversion fluorescence spectrum: The upconversion fluorescence spectrum (PL) of rare earth element (Yb, Er) doped TiO2 samples was tested by fluorescence spectrometer to study the photoelectric properties of rare earth element (Yb, Er) doped TiO2 samples;

[0092] (3) UV-Vis diffuse reflectance spectroscopy: The UV-Vis absorption spectra of the photoanode before and after dye sensitization were tested by UV-Vis spectrophotometer to study the light-harvesting ability of DC-TiO2, D-TiO2, C-TiO2 and pure TiO2 thin film photoelectrodes;

[0093] (4) Photovoltage-photocurrent curve test (JV curve): The photovoltage-photocurrent curve test (JV curve) of the dye-sensitized solar cell was conducted using an HPS-300XA xenon lamp solar simulator as the light source, with a light intensity condition of 100 mW / cm². 2 (One standard sunlight). Calibration was performed using a standard silicon cell at 1.5V before testing. The photoanode was connected to the working electrode of the electrochemical workstation, and the counter electrode and reference electrode were connected to a platinum counter electrode, placed under a simulated sunlight source. Finally, the photovoltage-photocurrent curve of the dye-sensitized solar cell was tested using a computer-controlled electrochemical workstation. The effective photoanode area of ​​the cell was 0.25 cm². 2 ;

[0094] (5) Photovoltaic conversion efficiency (%): The short-circuit current density (J) is read at the intersection of the voltage-current curve (JV curve) and the vertical axis. sc The open-circuit voltage (V) is read from the intersection of the curve and the horizontal axis. oc Substitute into the following formula The photoelectric conversion efficiency can be calculated.

[0095] (6) Short-circuit current (mA / cm²): The short-circuit current density (J) can be directly read at the intersection of the voltage-current curve (JV curve) and the vertical axis. sc ).

[0096] III. Test Results of Examples / Comparative Examples:

[0097] Table 1. Test results of dye-sensitized solar cells in the examples / comparative examples.

[0098]

[0099] In Comparative Example 1, glucose has a smaller mass than (Yb,Er)-doped TiO2 nanomaterials, resulting in incomplete coating and difficulty in significantly improving the photoelectric conversion efficiency of the battery. In Comparative Example 2, the excessive carbon source provided by glucose leads to structural instability. In Comparative Example 3, the calcination time is too short, resulting in unstable bonding between the carbon coating layer and the (Yb,Er)-doped TiO2 nanomaterials, thus reducing the photoelectric conversion efficiency of the battery. In Comparative Example 4, the calcination time is too long, leading to carbon source loss and further reducing the photoelectric conversion efficiency of the battery.

[0100] Comparative Example 5 shows that if the temperature of the hydrothermal method using carbohydrate carbon sources is too low and does not reach the suitable temperature range required for the reaction, it may not be able to effectively activate the decomposition reaction of glucose and its interaction with TiO2, thus making the carbon coating process difficult and ultimately affecting the quality and performance of the product. Glucose may not be able to form a complete carbon coating layer on the TiO2 surface in a short time, resulting in uneven carbon coating; some TiO2 particles may not be completely covered by carbon, thus affecting its overall performance. In Comparative Example 6, if the temperature of the hydrothermal method using carbohydrate carbon sources is too high, it may cause the carbon layer to sinter and agglomerate, forming an uneven thick carbon layer, or even graphitization of carbon, altering the electronic structure and conductivity of carbon, thereby adversely affecting the performance of carbon-coated TiO2.

[0101] Figure 1 This is a schematic diagram of the structure of a graphite-like carbon-coated (Yb, Er)-doped TiO2 nanocrystalline photoanode film. It features a bilayer structure on conductive glass. The first layer is coated with fine P25-TiO2 particles. The second layer is coated with graphite-like carbon-coated rare-earth ion (Yb, Er)-doped TiO2 particles, which have larger grain sizes. This bilayer structure design promotes the reflection of incident light within the film, enhancing light absorption efficiency.

[0102] Figure 2 XRD patterns of four samples are shown: graphite-carbon-coated co-doped TiO2 nanoparticles (DC-TiO2), uncoated TiO2 nanoparticles (D-TiO2), undoped TiO2 nanoparticles with graphite-carbon-coated particles (C-TiO2), and pure TiO2. Figure 2It can be seen that anatase structure appears in DC-TiO2, but rutile structure does not appear. Specifically, anatase-type TiO2: in 2 θ The diffraction peaks appearing at 25.3°, 37.8°, and 48° correspond to anatase characteristic peaks, and to crystal planes (101), (004), and (200), respectively. Rutile TiO2: In 2... θ The diffraction peaks at 27.5°, 36.1°, and 54.3° correspond to characteristic peaks of rutile TiO2, corresponding to crystal planes (110), (101), and (211), respectively. This indicates that during calcination, the carbon layer inhibits the transformation of the TiO2 crystal structure to a rutile structure, preserving the anatase structure. The D-TiO2 sample exhibits wider diffraction peaks and includes diffraction peaks corresponding to Yb2Ti2O7 and Er2Ti2O7. This is because Yb 3+ Er 3+ Entering TiO2 to partially replace Ti in TiO2 4+ This alters the cell space of TiO2, indicating that rare earth elements have been successfully incorporated into TiO2. Furthermore, the relatively lower diffraction peak intensity and smaller grain size of the rare earth-doped elements suggest that Yb... 3+ Er 3+ Doping can suppress grain growth. Titanium dioxide materials with smaller grains have a larger specific surface area, which can adsorb more dye molecules and improve the photocurrent density of the battery.

[0103] Figure 3 The figure shows the upconversion fluorescence spectrum of rare earth element (Yb, Er) doped TiO2. As can be seen from the figure, under infrared excitation at 980 nm, the rare earth element (Yb, Er) doped TiO2 emits visible light in the 525–570 nm and 630–730 nm ranges, corresponding to the green and red light of the solar spectrum, respectively. This indicates that the Yb doping... 3+ Er 3+ TiO2 has an upconversion function and can utilize Yb 3 + Er 3+ The energy level characteristics of the dye absorb multiple low-frequency long-wavelength lights and emit high-frequency short-wavelength lights when excited by photons, thereby converting the light in the near-infrared spectral region into visible light that can be absorbed by the dye, thus increasing the number of photons absorbed and electrons generated by the dye.

[0104] Figure 4 and Figure 5 The images show the UV-Vis diffuse reflectance spectra of photoanodes for DC-TiO2, D-TiO2, C-TiO2, and pure TiO2 before and after sensitization. Figure 4It can be seen that the DC-TiO2 photoanode exhibits the highest peak value in the 200nm~350nm range, followed by the D-TiO2 photoanode, while the pure TiO2 photoanode shows the lowest peak value, indicating that the DC-TiO2 photoanode exhibits the strongest light absorption. This is because the double-layer structure design causes multiple light scattering within the thin film, improving the utilization rate of sunlight. Figure 5 It can be seen that after soaking in dye, the four different photoanodes all showed different degrees of light absorption in the wavelength range of 450nm~700nm, which is well adapted to the wavelength absorption range of N719. Moreover, the absorbance of the photoanodes is also different in the visible light range. This is not only related to the design of the double-layer structure, but also because the graphite-like carbon coating on the rare earth doped TiO2 surface inhibits the grain growth and phase transformation of TiO2, which can adsorb more dye molecules and improve the photoelectric performance of dye-sensitized solar cells.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. The application of a graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film in the preparation of dye-sensitized solar cells, characterized in that, The graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film includes a bilayer structure, consisting of a P25-TiO2 nanocrystalline layer and a graphite-like carbon-coated Yb,Er-doped TiO2 nanoparticle layer. The graphite-like carbon-coated Yb,Er-doped TiO2 nanoparticle layer was prepared by a hydrothermal method using a sugar-based carbon source and by calcination treatment of the Yb,Er-doped TiO2 nanomaterials. The temperature for the hydrothermal method using carbohydrate carbon sources is 160~190℃; The calcination time is 1-4 hours; The mass ratio of the Yb,Er-doped TiO2 nanomaterial to the carbohydrate carbon source is 2~4:

3.

2. The application according to claim 1, characterized in that, The carbohydrate carbon source is one or both of monosaccharides or disaccharides.

3. The application according to claim 1, characterized in that, The temperature for the hydrothermal method using carbohydrate carbon sources is 170~180℃.

4. The application according to claim 1, characterized in that, The hydrothermal method using carbohydrate carbon sources takes 4-5 hours.

5. The application according to claim 1, characterized in that, The calcination temperature is 750~850℃.

6. The application according to claim 1, characterized in that, The thickness of the double-layer structure is 9~11μm.

7. The application according to claim 1, characterized in that, The preparation method of the graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film includes the following steps: P25-TiO2 was made into a slurry, and Yb,Er-doped TiO2 nanopowder coated with graphite-like carbon was also made into a slurry. The slurry was then printed onto conductive glass by screen printing and cured to form a thin film. After heating and curing, a composite photoanode thin film was obtained.

8. The application according to claim 7, characterized in that, The screen printing method involves printing each layer of the structure twice.

9. The application according to claim 7, characterized in that, The heating and curing conditions are 440~460℃, and the temperature is maintained for 30~45 minutes.

10. The application according to claim 1, characterized in that, The dye-sensitized solar cell comprises a photoanode, a dye sensitizer, an electrolyte, and a counter electrode, all prepared from the graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode film and conductive glass.

Images