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

Abstract

The invention relates to application of a graphite-like carbon coated rare earth doped TiO2 composite photo-anode film, and belongs 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 sequentially comprises a P25-TiO2 nanocrystalline layer and a graphite-like carbon coated (Yb, Er) doped TiO2 nano-particle layer, and the (Yb, Er) doped TiO2 nano-material passes through a carbohydrate carbon source to prepare the graphite-like carbon coated rare earth doped TiO2 composite photo-anode film. TiO2 crystal grains maintain an anatase phase, so that the photoelectric conversion efficiency of the dye-sensitized solar cell is improved.

Description

Technical Field

[0001] The present 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 Art

[0002] With economic development, people's demand for energy is increasing. However, traditional fossil fuels are non-renewable and pollute the environment. Efforts are underway to develop and utilize alternative energy sources to reduce reliance on fossil fuels, and solar energy presents an ideal alternative. Solar energy is a renewable, green energy source that is abundant, free to use, requires no transportation, and poses no environmental pollution. It has created a new way of life for humanity, ushering in an era of energy conservation and pollution reduction. Solar power generation offers advantages such as safety, reliability, noiselessness, and pollution-free operation. It requires no high-voltage transmission lines, has a short construction period, is scalable, and can operate unmanned. The development and utilization of solar energy, a renewable, green energy source, can lay a solid foundation for the coordinated and sustainable development of the economy, the environment, and society. Early solar cells were manufactured using single-crystalline silicon. These solar cells required stringent processing and equipment requirements, and their high production costs hindered widespread adoption. As a new generation of solar cell products, dye-sensitized solar cells (DSSCs) have a cost 90% lower than silicon cells. They have a simple and pollution-free preparation process, a high technical level, and potentially high photoelectric conversion efficiency. Therefore, they are very likely to replace traditional silicon solar cells and become the dominant solar cell in the future. A typical dye-sensitized solar cell (DSSC) consists of three main components: a dye-sensitized semiconductor photoanode, a platinum counter electrode, and an electrolyte. As a crucial component of a DSSC, the performance of the photoanode significantly impacts the DSSC's photoelectric conversion efficiency. The photoanode is made by coating a conductive glass with a dye-adsorbed semiconductor film. This semiconductor film absorbs the dye and transfers the electrons generated by the dye to the conductive glass.

[0003] The prior art discloses a rare-earth-doped upconversion TiO2 nanostructured composite photoanode and its application. The composite photoanode comprises a TiO2 nanosheet layer and a (Yb, Er) co-doped TiO2 nanocrystal layer. (Yb, Er) co-doped TiO2 nanocrystals and TiO2 nanosheets are first prepared separately. These nanocrystals and nanosheets are then added to a mixture of ethyl cellulose in ethanol and terpineol in ethanol, and OP emulsifier and acetylacetone are added dropwise with stirring. The resulting suspension is then sonicated and heated at 75-85°C until the ethanol completely evaporates, producing a (Yb, Er) co-doped TiO2 nanocrystal slurry and a TiO2 nanosheet slurry. These slurries are then printed layer by layer on a conductive substrate and dried to produce a photoanode thin film. However, the resulting photoanode thin film still suffers from low photoelectric conversion efficiency.

[0004] Therefore, an 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 therein maintain the anatase phase, thereby improving the photoelectric conversion efficiency of the cell. Summary of the Invention

[0005] In order to address the deficiencies in the prior art, the primary purpose of the present invention is to provide an application of a graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film for the preparation of dye-sensitized solar cells, wherein the TiO2 grains maintain an anatase phase, thereby improving the photoelectric conversion efficiency of the cell.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: The present invention protects the use of a graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film in the preparation of a dye-sensitized solar cell. The graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film comprises a double-layer structure, which is sequentially composed 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 is prepared by hydrothermal treatment of a sugar carbon source and calcination of (Yb, Er)-doped TiO2 nanomaterials; The temperature of the carbohydrate carbon source hydrothermal method is 160-190°C; The calcination time is 1 to 4 hours; The mass ratio of the (Yb, Er)-doped TiO2 nanomaterial to the sugar carbon source is 2-4:3.

[0007] This invention utilizes graphite-like carbon coating on rare earth (Yb, Er)-doped TiO2 nanomaterials to produce a graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film. This effectively prevents TiO2 grain growth, maintains the anatase phase structure, and possesses excellent electrical conductivity, creating an efficient electron transport channel. Furthermore, the bilayer structure of a P25-TiO2 nanocrystal layer and graphite-like carbon-coated (Yb, Er)-doped TiO2 nanoparticles allows for multiple scattering of incident light within the film, enhancing light capture. This graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film is used in dye-sensitized solar cells to improve the cell's photoelectric conversion efficiency.

[0008] P25-TiO2 is a nanomaterial in the prior art that contains a mixed phase of anatase and rutile TiO2.

[0009] Preferably, the carbohydrate carbon source is one or both of monosaccharides and disaccharides.

[0010] Preferably, the temperature of the carbohydrate carbon source hydrothermal method is 170-180°C.

[0011] Preferably, the hydrothermal method of the carbohydrate carbon source is carried out for 4 to 5 hours.

[0012] Preferably, the calcination temperature is 750-850°C.

[0013] Preferably, the thickness of the double-layer structure is 9-11 μm.

[0014] Preferably, the method for preparing the graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film comprises the following steps: P25-TiO2 is made into a slurry, and graphite-like carbon-coated (Yb, Er)-doped TiO2 nanopowder is made into a slurry, which is sequentially printed on conductive glass by screen printing and solidified to form a thin film. After heating and curing, a composite photoanode film is obtained.

[0015] Preferably, the curing conditions of the P25-TiO2 slurry are standing for 10 minutes and drying at 60°C for 15 minutes.

[0016] Preferably, the curing conditions for the slurry made of the graphite-like carbon-coated (Yb, Er)-doped TiO2 nanopowder are standing for 10 minutes and drying at 60°C for 24 hours.

[0017] Preferably, the heating and curing conditions are 440-460° C. and the heat preservation time is 30-45 minutes.

[0018] Preferably, the screen printing method is performed twice for each layer of the structure.

[0019] Specifically, the method for preparing the (Yb, Er)-doped TiO2 nanopowder comprises the following steps: Pour ethanol, tetrabutyl titanate and acetylacetone into a beaker and stir to form solution A; mix ethanol, deionized water and hydrochloric acid to form solution B; drop solution B into solution A to form a light yellow precursor solution; add a rare earth ion source to the light yellow precursor solution and stir until completely dissolved to form solution C; heat solution C at 50-70°C and stir, while adding deionized water dropwise and stirring until a gel is formed; freeze-dry the gel and heat it to 500-900°C before calcining to obtain (Yb, Er) co-doped TiO2 nanocrystals.

[0020] Specifically, the method for preparing the slurry of graphite-like carbon-coated (Yb, Er)-doped TiO2 nanopowder comprises the following steps: S1. Dissolve ethyl cellulose in ethanol and mix well to obtain solution A; S2. Dissolve terpineol in ethanol and mix well to obtain solution B; S3. Slowly add solution B dropwise to solution A, add OP emulsifier and acetylacetone, stir evenly, then add graphite-like carbon-coated (Yb, Er)-doped TiO2 nanopowder, mix evenly, and ultrasonicate in a water bath until it becomes viscous to obtain graphite-like carbon-coated (Yb, Er)-doped TiO2 nanopowder slurry.

[0021] Preferably, the dye-sensitized solar cell comprises the above-mentioned graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film and a photoanode prepared from conductive glass, a dye sensitizer, an electrolyte and a counter electrode.

[0022] Preferably, the method for preparing the dye-sensitized solar cell comprises the following steps: Prepare a catalytic layer on conductive glass to serve as the counter electrode, drying it for later use. Place the graphite-like carbon-coated rare-earth-doped TiO2 composite photoanode and the counter electrode face-to-face, with a sealing layer in between. Heat-press at 110-130°C to seal the electrode, leaving a pre-recorded injection port. Inject the electrolyte through the port, and seal the port with curing adhesive.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an application of a graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film, which is applied to the preparation of dye-sensitized solar cells. The graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film includes a double-layer structure, which is sequentially a P25-TiO2 nanocrystalline layer and a graphite-like carbon-coated (Yb, Er)-doped TiO2 nanoparticle layer. The (Yb, Er)-doped TiO2 nanomaterial is modified by a sugar carbon source, hydrothermal treatment, and calcination, wherein the TiO2 grains maintain an anatase phase, thereby improving the photoelectric conversion efficiency of the dye-sensitized solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of graphite-like carbon-coated (Yb, Er)-doped TiO2 nanocrystal photoanode; Figure 2 The 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 are shown; Figure 3 This is the up-conversion fluorescence spectrum of rare earth elements (Yb, Er) doped TiO2; Figure 4 UV-visible diffuse reflectance absorption spectra of DC-TiO2, D-TiO2, C-TiO2 and pure TiO2 photoanode before sensitization; Figure 5 These are the UV-visible diffuse reflectance absorption spectra of the photoanodes sensitized by DC-TiO2, D-TiO2, C-TiO2 and pure TiO2. DETAILED DESCRIPTION

[0025] The present invention is further described below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed in the present invention.

[0026] 1. Experimental Methods Preparation of (Yb, Er) doped TiO2 nanomaterials by sol-gel method: (1) Use a measuring cylinder to take 95.0 mL of tetra-n-butyl titanate, 150.0 mL of tert-butyl alcohol, and 10.0 mL of acetylacetone into a beaker and stir evenly to obtain a light yellow solution A. (2) Using an analytical balance, weigh 2.4 g of ytterbium nitrate pentahydrate and 12 g of erbium nitrate pentahydrate and add them to 25 mL of deionized water, 78 mL of tert-butyl alcohol, and 0.5 mL of HCl to form a clear mixed solution B. (3) Solution B was slowly dripped into solution A with a rubber-tipped dropper. After mixing and stirring for 8 minutes, a yellow gel appeared on the beaker. The stirring was continued until the stirrer stopped rotating. The gel was placed in a refrigerator and frozen for 24 hours. It was then dried in a freeze dryer for 72 hours. Finally, the dried sample was ground to obtain rare earth element (Yb, Er)-doped TiO2 powder for use. The condensation temperature was 233.15K and the vacuum degree was 36MPa.

[0027] Example 1 S1. Preparation of graphite-like carbon-coated (Yb, Er)-doped TiO2 powder: (1) Weigh 3 g of (Yb, Er)-doped TiO2 nanomaterial and 3 g of glucose, i.e., the mass ratio of the (Yb, Er)-doped TiO2 nanomaterial to glucose is 1:1, add them into 145 mL of deionized water, stir magnetically for 30 min to mix the solution evenly, and ultrasonicate in an ultrasonic cleaner for 20 min; (2) Place the mixed solution from step (1) in a muffle furnace and perform a hydrothermal reaction at 180°C for 4 hours; (3) The precipitate obtained in step (2) was centrifuged at 6000 r for 10 min, and then the sample was taken out and ultrasonicated in an ultrasonic cleaner for 30 s. The operation was repeated 3 times until the solution was neutral. The sample was then freeze-dried for 12 h and calcined in a muffle furnace at 800 °C for 3 h to obtain a white powder, i.e., a sample of graphite-like carbon-coated TiO2 (DC-TiO2); S2. Preparation of graphite-like carbon-coated (Yb, Er)-doped TiO2 slurry: (1) Weigh 0.56 g of ethyl cellulose, add it to 7 mL of anhydrous ethanol, and stir it magnetically to obtain solution A; (2) Weigh 4.10 g of terpineol and add it to 6 mL of anhydrous ethanol. Stir magnetically to obtain solution B. (3) Solution B was slowly added dropwise to solution A. During the addition, a magnetic stirrer was used to stir and mix. Then, 0.05 mL of OP emulsifier and 0.5 mL of acetylacetone were added. After stirring evenly, 2 g of the above-mentioned DC-TiO2 powder was added. The solution was further stirred evenly, ultrasonicated for 13 min, and stirred in an 85°C water bath until it became viscous to obtain a DC-TiO2 slurry. S3. Screen printing method: The slurry is brushed onto the conductive glass substrate using the screen printing method. The first layer is uniformly brushed with P25-TiO2 slurry twice, allowed to stand for 10 minutes, and then dried at 60°C for 15 minutes. The second layer is brushed with DC-TiO2 slurry twice, allowed to stand for 10 minutes, and then dried at 60°C for 24 hours. After drying, it is placed in a muffle furnace and calcined at 450°C for 30 minutes. After natural cooling, it is immersed in N719 dye solution, wrapped with tin foil to keep the TiO2 film in a dark place, and dried in a 50°C humidity drying oven for 24 hours to allow the dye to be fully adsorbed on the TiO2 film. Finally, it is washed with anhydrous ethanol and dried at 50°C for 1 hour to obtain a dye-sensitized photoanode. The screen printing method requires screen printing twice (2 layers) for each layer structure, and a total of 4 times (4 layers) for the double-layer structure. The film thickness of each screen printing is about 2.66μm, and the film thickness of the double-layer structure is about 10.64μm. S4. Assemble the dye-sensitized solar cell: Prepare a catalyst layer on the counter electrode (conductive glass), apply carbon slurry, and dry it for later use. Place the prepared photoanode and counter electrode face to face, using a sealing layer (Surlyn film) between them. Heat-press at 120°C to seal, leaving an injection port. Inject electrolyte through the injection port, and seal the port with UV-curable adhesive.

[0028] Example 2 The experimental conditions are the same as those in Example 1, except that in step S1, the mass ratio of the (Yb, Er)-doped TiO2 nanopowder to glucose is 2:3.

[0029] Example 3 The experimental conditions are the same as those in Example 1, except that in step S1, the mass ratio of the (Yb, Er)-doped TiO2 nanopowder to glucose is 4:3.

[0030] Example 4 The experimental conditions were the same as those in Example 1, except that the calcination time in step S1. (3) was 2 h.

[0031] Example 5 The experimental conditions were the same as those in Example 1, except that the calcination time in step S1. (3) was 4 h.

[0032] Example 6 The experimental conditions are the same as those in Example 1, except that in step S1, the carbohydrate carbon source is sucrose.

[0033] Example 7 The experimental conditions are the same as those in Example 1, except that in step S1, the carbohydrate carbon source is fructose.

[0034] Example 8 The experimental conditions were the same as those in Example 1, except that the temperature of the carbohydrate carbon source hydrothermal method in step S1. (2) was 160°C.

[0035] Example 9 The experimental conditions were the same as those in Example 1, except that the temperature of the carbohydrate carbon source hydrothermal method in step S1. (2) was 170°C.

[0036] Example 10 The experimental conditions were the same as those in Example 1, except that the temperature of the carbohydrate carbon source hydrothermal method in step S1. (2) was 190°C.

[0037] Comparative Example 1 The experimental conditions are the same as those in Example 1, except that in step S1, the mass ratio of the (Yb, Er)-doped TiO2 nanopowder to glucose is 1:3.

[0038] Comparative Example 2 The experimental conditions are the same as those in Example 1, except that in step S1, the mass ratio of the (Yb, Er)-doped TiO2 nanopowder to glucose is 5:3.

[0039] Comparative Example 3 The experimental conditions were the same as those in Example 1, except that the calcination time in step S1. (3) was 0.5 h.

[0040] Comparative Example 4 The experimental conditions were the same as those in Example 1, except that the calcination time in step S1. (3) was 5 h.

[0041] Comparative Example 5 The experimental conditions were the same as those in Example 1, except that the temperature of the carbohydrate carbon source hydrothermal method in step S1. (2) was 150°C.

[0042] Comparative Example 6 The experimental conditions were the same as those in Example 1, except that the temperature of the carbohydrate carbon source hydrothermal method in step S1. (2) was 200°C.

[0043] 2. Test indicators of embodiment / comparative example: (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), a scanning range of 2θ = 20° to 80°, and a scanning speed of 10° / min. (2) Upconversion fluorescence spectroscopy: The fluorescence upconversion 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; (3) UV-visible diffuse reflectance spectroscopy: The UV-visible absorption spectra of the photoanode before and after dye sensitization were tested by UV-visible spectrophotometer to study the light capture ability of DC-TiO2, D-TiO2, C-TiO2 and pure TiO2 thin film photoelectrodes; (4) Photovoltage-photocurrent curve test (JV curve): The photovoltage-photocurrent curve test (JV curve) of dye-sensitized solar cells uses a HPS-300XA xenon lamp solar simulator as the light source, with a light intensity of 100 mW / cm 2 (1 standard sunlight). Before testing, a standard silicon cell with a voltage of 1.5V was used for calibration. The working electrode of the electrochemical workstation was connected to the photoanode, and the counter and reference electrodes were connected to the platinum counter electrode. The cells were placed under simulated sunlight. 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 cm 2 ; (5) Photoelectric 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 oc ), substitute into the following formula , the value of photoelectric conversion efficiency can be calculated; (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 ).

[0044] 3. Example / Comparative Example Test Results: Table 1 Test results of dye-sensitized solar cells of Examples / Comparative Examples

[0045] In comparative example 1, the mass of glucose is smaller than that of (Yb, Er)-doped TiO2 nanomaterials, and the coating is not thorough, making it difficult to significantly improve the photoelectric conversion efficiency of the battery; in comparative example 2, the carbon source brought by glucose is too much, which will make the structure unstable; in comparative example 3, the calcination time is too short, the combination of the carbon coating layer and the (Yb, Er)-doped TiO2 nanomaterials is unstable, and the photoelectric conversion efficiency of the battery is reduced; in comparative example 4, the calcination time is too long, the carbon source is lost, and the photoelectric conversion efficiency of the battery is reduced.

[0046] The temperature of the hydrothermal method for the carbohydrate carbon source obtained in Comparative Example 5 is too low and does not reach the temperature range required for the appropriate reaction. It may not be possible to effectively activate the decomposition reaction of glucose and its interaction with TiO2, thereby making the carbon coating process difficult to carry out, 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 period of time, resulting in uneven carbon coating, and some TiO2 particles may not be completely covered by carbon, thereby affecting its overall performance. The temperature of the hydrothermal method for the carbohydrate carbon source obtained in Comparative Example 6 is too high, which may cause the carbon layer to sinter and agglomerate, forming an uneven thick carbon layer, and even graphitization of carbon, changing the electronic structure and electrical conductivity of carbon, and thus adversely affecting the performance of carbon-coated TiO2.

[0047] Figure 1 This diagram illustrates the structure of a graphite-like carbon-coated (Yb, Er)-doped TiO2 nanocrystalline photoanode film. The film is constructed as a double-layer structure on conductive glass. The first layer is coated with P25-TiO2, which has finer particles. The second layer is coated with graphite-like carbon-coated rare earth ion (Yb, Er)-doped TiO2, which has larger grains. This double-layer design promotes reflection of incident light within the film, enhancing light absorption efficiency.

[0048] Figure 2 The XRD patterns of four samples are graphite-like carbon-coated co-doped TiO2 nanoparticles (DC-TiO2), non-graphite-like carbon-coated TiO2 nanoparticles (D-TiO2), non-doped graphite-like carbon-coated TiO2 nanoparticles (C-TiO2) and pure TiO2. Figure 2 It can be seen that anatase structure appears in DC-TiO2, but rutile structure does not appear. θ The diffraction peaks at 25.3°, 37.8°, and 48° correspond to the characteristic peaks of anatase, corresponding to the crystal planes (101), (004), and (200), respectively. Rutile TiO2: At 2 θ The diffraction peaks at 27.5°, 36.1°, and 54.3° correspond to the characteristic peaks of rutile TiO2, corresponding to the crystal planes (110), (101), and (211), respectively. This shows that during the calcination process, the protection of the carbon layer inhibited the transformation of the TiO2 crystal structure to the rutile structure, and the anatase structure was retained. The diffraction peak width of the D-TiO2 sample is relatively wide, and the diffraction peaks corresponding to Yb2Ti2O7 and Er2Ti2O7 appear. This is because Yb 3+ , Er 3+ Enter TiO2 to partially replace Ti in TiO2 4+ , which causes the unit cell space of TiO2 to change, indicating that rare earth elements are successfully doped into TiO2. In addition, the diffraction peak intensity of rare earth doping is relatively reduced, and the grains are smaller, indicating that Yb3+ , Er 3+ Doping can inhibit grain growth. Titanium dioxide materials with smaller grains have a larger specific surface area, which can adsorb more dye molecules and increase the photocurrent density of the battery.

[0049] Figure 3 The up-conversion fluorescence spectrum of rare earth element (Yb, Er) doped TiO2 is shown in the figure. As can be seen from the figure, under the excitation of 980nm infrared light, rare earth element (Yb, Er) doped TiO2 emits visible light in the range of 525~570nm and 630~730nm, which correspond to the green and red light of the solar spectrum respectively. This shows that Yb doped TiO2 emits visible light in the range of 525~570nm and 630~730nm. 3+ , Er 3+ TiO2 has an up-conversion function and can utilize Yb 3 + , Er 3+ The energy level characteristics of the dye absorb multiple low-frequency long-wave lights and emit high-frequency short-wave light under photon excitation, thereby converting light in the near-infrared spectrum region into visible light that can be absorbed by the dye, thereby increasing the number of photons absorbed by the dye and the number of electrons generated.

[0050] Figure 4 and Figure 5 The UV-visible diffuse reflectance spectra of the photoanode of DC-TiO2, D-TiO2, C-TiO2 and pure TiO2 before and after sensitization are shown in Figure 2. Figure 4 It can be seen that the peak value of DC-TiO2 photoanode in the range of 200nm~350nm is the highest, followed by D-TiO2 photoanode, while the peak value of pure TiO2 photoanode is the lowest, indicating that DC-TiO2 photoanode exhibits the strongest light absorption. This is because the design of the double-layer structure causes the incident light to scatter multiple times inside the film, thereby improving the utilization rate of sunlight. Figure 5 It can be found that after soaking in dye, the four different photoanodes 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 photoanode is different in the visible light range. This is not only related to the design of the double-layer structure, but also the graphite-like carbon coating on the rare earth-doped TiO2 surface inhibits the grain growth and phase transition of TiO2, can adsorb more dye molecules, and improve the photoelectric performance of dye-sensitized solar cells.

[0051] 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 the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. 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 comprises a double-layer structure, which is 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 is prepared by hydrothermal treatment of a sugar carbon source and calcination of (Yb, Er)-doped TiO2 nanomaterials; The temperature of the carbohydrate carbon source hydrothermal method is 160-190°C; The calcination time is 1 to 4 hours; The mass ratio of the (Yb, Er)-doped TiO2 nanomaterial to the sugar carbon source is 2-4:

3.

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

3. The application according to claim 1, characterized in that The temperature of the carbohydrate carbon source hydrothermal method is 170-180°C.

4. The application according to claim 1, characterized in that The time of the carbohydrate carbon source hydrothermal method is 4 to 5 hours.

5. The application according to claim 1, characterized in that: The calcination temperature is 750-850°C.

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

7. The use according to claim 1, characterized in that The method for preparing the graphite-like carbon-coated rare earth-doped TiO2 composite photoanode film comprises the following steps: P25-TiO2 is made into a slurry, and graphite-like carbon-coated (Yb, Er)-doped TiO2 nanopowder is made into a slurry, which is sequentially printed on conductive glass by screen printing and solidified to form a thin film. After heating and curing, a composite photoanode film is obtained.

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

9. The application according to claim 7, characterized in that: The heating and curing conditions are 440-460° C. and heat preservation for 30-45 minutes.

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

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