TiO2 chemical bath deposition technology for synchronously realizing deposition regulation and doping

Abstract

The invention discloses a TiO2 chemical bath deposition technology for synchronously realizing deposition regulation and doping. The TiO2 chemical bath deposition technology specifically comprises the following steps: (1) preparing a precursor solution by using a titanium tetrachloride solution; (2) adding a flocculation regulation doping agent SnCl2. 2H2O into the prepared solution; (3) cleaning a substrate, namely cleaning the substrate in an ultraviolet ozone machine and putting the substrate at the bottom of a container; (4) after the step (3) is completed, pouring the solution obtained in the step (2) into a container; (5) after the step (4) is completed, putting into a water bath kettle, taking out the container after waiting for a period of time, and cleaning with deionized water; and (6) washing the FTO glass obtained in the step (5) according to the sequence of water, ethanol and water, and blow-drying by using a nitrogen gas gun. The invention provides a simple, convenient and efficient film forming technology for chemical bath deposition of a thin film, smaller nano particles can be effectively deposited, and a compact TiO2 thin film with reduced roughness is obtained. Meanwhile, Sn ions in the flocculating agent are doped into TiO2 crystal lattices, so that the conductivity of the thin film is improved.

Description

Technical Field

[0001] The invention relates to the field of chemical bath deposition film manufacturing, and in particular provides a TiO2 chemical bath deposition technology for synchronously realizing deposition regulation and doping. Background Art

[0002] With the rapid development of high-quality photovoltaic power generation, perovskite solar cells have attracted much attention, among which the electron transport layer plays an important role. Among them, TiO2 is one of the widely used electron transport layers. At present, the photoelectric conversion efficiency of planar perovskite solar cells based on TiO2 electron transport layer is low, which is mainly caused by the characteristics of TiO2 film and its interface contact characteristics. It is reported that due to the low conductivity of TiO2 electron transport layer and its mismatched band alignment with perovskite, TiO2-based perovskite solar cells suffer from strong electron accumulation and low open circuit voltage. In order to improve the quality of TiO2 electron transport layer, researchers have widely explored various deposition techniques, including spin coating, spray pyrolysis and chemical bath deposition. It is worth noting that chemical bath deposition has the advantages of low temperature and conformal deposition, making it particularly suitable for transparent conductive substrates such as fluorine-doped tin oxide (FTO). However, this method still faces challenges of low-temperature process, such as difficult to control crystal nucleation and orientation, and highly corrosive acidic environment (pH < 0.5), which decomposes many organic or inorganic additives. Few studies have mentioned and achieved the balance between the deposition and doping processes of TiO2 in low-temperature chemical bath preparation to achieve synergistic optimization. Based on the above insights, we believe that the synergistic integration of deposition control and doping may be an effective strategy to obtain high-quality TiO2 electron transport layers, thereby improving the performance of perovskite solar cells in various applications. Therefore, proposing a TiO2 chemical bath deposition technology that simultaneously achieves deposition control and doping is of great significance for the preparation of high-quality TiO2 films and efficient perovskite solar cells. Summary of the invention

[0003] The purpose of the present invention is to provide a TiO2 chemical water bath deposition technology that can simultaneously achieve deposition regulation and doping, so as to prepare a flat, dense, and conductive TiO2 film. The present invention proposes a TiO2 deposition regulation technology based on the flocculation effect, so as to simultaneously achieve deposition optimization and element doping, wherein the flocculation dopant is SnCl2·2H2O, which can not only regulate the water bath process through the flocculation effect to obtain a dense TiO2 film with reduced surface roughness, but also improve the TiO2 conductivity and TiO2 energy level structure through Sn doping, so as to further improve the efficiency of TiO2-based perovskite solar cells.

[0004] The specific contents of the TiO2 chemical bath deposition technology for synchronously realizing deposition regulation and doping provided by the present invention are as follows:

[0005] (1) using titanium tetrachloride (TiCl4) and deionized water to prepare a chemical bath deposition solution, wherein the volume ratio of TiCl4 to water is 0.005 to 0.04, and stirring evenly for later use;

[0006] (2) Adding a flocculation adjustment dopant SnCl2·2H2O to the prepared chemical bath deposition solution, wherein the doping concentration of SnCl2·2H2O relative to TiCl4 is between 0.05 and 1 mol%, stirring the solution uniformly, and controlling the solution temperature between 5 and 55° C. for standby use;

[0007] (3) Clean the clean substrate (taking fluorine-doped tin oxide (FTO) substrate as an example) in a UV ozone machine for 5 to 60 minutes and place it at the bottom of a sealed container after cleaning;

[0008] (4) After step (3) is completed, the chemical water bath deposition solution obtained in step (2) is slowly poured into the container along the inner wall of the container. The solution needs to completely immerse the substrate and the volume of the solution accounts for 1 / 10 to 2 / 3 of the volume of the container;

[0009] (5) After step (4) is completed, the container is placed in a water bath at a temperature of 45 to 90° C. for 20 to 90 minutes;

[0010] (6) Take out the sealed container from the water bath, then take out the FTO substrate with the TiO2 film deposited thereon, rinse the FTO substrate with water, ethanol, and water in that order, blow dry it with a nitrogen air gun, and store it in an oven at a temperature range of 15 to 50°C for later use. At this point, a Sn-doped TiO2 film with deposition control is prepared.

[0011] In the process of preparing TiO2 thin film by using the above technical scheme, after adding SnCl2·2H2O, Sn 2+ Ions can react with [Ti(OH) n Cl m ] 2- The hydroxyl compounds of SnCl2·2H2O can coordinate to form a polar bridging structure, thereby promoting the formation of large-sized aggregated particles. The added SnCl2·2H2O acts as a flocculant in the hydrolysis process, which can adsorb and bridge the suspended TiO2 particles and promote the flocculation and precipitation of TiO2 nanoparticles. This can remove oversized TiO2 nanoparticles and leave TiO2 nanoparticles of appropriate size for deposition, thereby achieving uniform and dense TiO2 film preparation. During the deposition process, SnCl2·2H2O can also participate in the hydrolysis, Sn 2+ It can also enter the TiO2 lattice in the form of doping to achieve Sn element doping and improve the conductive properties of TiO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram of the mechanism of preparing a thin film according to an embodiment of the present invention;

[0013] Figure 2 is a SEM comparison picture of the thin film prepared according to the embodiment of the present invention;

[0014] Figure 3 is a schematic diagram of doping of a thin film prepared in an embodiment of the present invention;

[0015] Figure 4 This is a conductivity test diagram performed after the film is prepared according to an embodiment of the present invention.

[0016] Specific implementation method (modified briefly according to the content of the invention)

[0017] Example 1 (Comparative Example): Chemical bath deposition of TiO2 thin film on FTO glass substrate without flocculating dopant.

[0018] (1) using titanium tetrachloride (TiCl4) solution to prepare chemical bath deposition solution, TiCl4 and water are mixed in a certain volume ratio (1:50), a magnetic particle is placed in the solution, and the mixture is stirred and mixed evenly on a stirring table with a certain speed, and the mixture is set aside;

[0019] (2) Clean the clean substrate (taking fluorine-doped tin oxide (FTO) substrate as an example) in a UV ozone machine for 30 minutes and place it at the bottom of a sealed container after cleaning;

[0020] (3) After step (2) is completed, the chemical water bath deposition solution obtained in step (1) is slowly poured into the container along the inner wall of the container. The solution must completely immerse the substrate and the volume of the solution accounts for 1 / 3 of the volume of the container;

[0021] (4) After step (3) is completed, the container is placed in a water bath at 70° C. for 35 min.

[0022] (5) Take out the sealed container from the water bath, then take out the FTO substrate with the TiO2 film deposited thereon, rinse the FTO substrate with water, ethanol, and water in that order, blow dry it with a nitrogen air gun, and place it in an oven at a temperature range of 50°C for future use. At this point, a Sn-doped TiO2 film with deposition control is prepared.

[0023] Example 2

[0024] (1) using titanium tetrachloride (TiCl4) solution to prepare chemical bath deposition solution, TiCl4 and water are mixed in a certain volume ratio (1:50), a magnetic particle is placed in the solution, and the mixture is stirred and mixed evenly on a stirring table with a certain speed, and the mixture is set aside;

[0025] (2) Adding flocculation adjustment dopant SnCl2·2H2O to the prepared chemical bath deposition solution, with a doping concentration of 0.25 mol%, stirring evenly, and controlling the solution temperature between 5 and 55° C. for standby use;

[0026] (3) Clean the clean substrate (taking fluorine-doped tin oxide (FTO) substrate as an example) in a UV ozone machine for 30 minutes and place it at the bottom of a sealed container after cleaning;

[0027] (4) After step (3) is completed, the chemical water bath deposition solution obtained in step (2) is slowly poured into the container along the inner wall of the container. The solution must completely immerse the substrate and the volume of the solution accounts for 1 / 3 of the volume of the container;

[0028] (5) After step (4) is completed, the container is placed in a water bath at 70° C. for 35 min.

[0029] (6) Take out the sealed container from the water bath, then take out the FTO substrate with the TiO2 film deposited thereon, rinse the FTO substrate with water, ethanol, and water in that order, blow dry it with a nitrogen air gun, and place it in an oven at a temperature range of 50°C for future use. At this point, a Sn-doped TiO2 film with deposition control is prepared.

[0030] The present invention is not limited to the above-described embodiments, and many changes in details are possible, but this does not affect the scope and spirit of the present invention.

[0031] Matters not covered by the present invention are known technologies.

[0032] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A TiO2 chemical bath deposition technology for simultaneous deposition control and doping, characterized in that: The following steps are involved: (1) preparing a chemical bath deposition solution using titanium tetrachloride (TiCl4) and deionized water, stirring and mixing the mixture evenly for later use; (2) adding a flocculation regulating dopant to the prepared TiCl4 aqueous solution, stirring and mixing the mixture evenly, and heating the mixture for later use; (3) Clean the FTO glass, clean it in a UV ozone machine, take it out and place it at the bottom of a sealed container; (4) After step (3) is completed, when the solution has been stirred and mixed evenly, immediately take the TiCl4 solution obtained in step (2) and slowly pour it into the container; (5) After step (4) is completed, immediately place the container in a water bath, wait for a while, remove the sealed container from the water bath, and wash it with a large amount of deionized water; (6) The FTO glass obtained in step (5) is rinsed with water, ethanol, and water in that order, blown dry with a nitrogen air gun, and stored in an oven.

2. A TiO2 chemical bath deposition technology for synchronously realizing deposition control and doping according to claim 1, characterized in that: In the water bath precursor solution preparation process described in step (1), the required volume ratio of TiCl4 to deionized water is 0.005-0.04, and a magnetic particle needs to be added and fully stirred.

3. A TiO2 chemical bath deposition technology for synchronously achieving deposition control and doping according to claim 1, characterized in that: The flocculation adjustment dopant added in step (2) is SnCl2·2H2O, and its concentration range relative to TiCl4 is 0.05-1 mol%, and it needs to be fully stirred after addition.

4. A TiO2 chemical bath deposition technology for synchronously achieving deposition control and doping according to claim 1, characterized in that: The prepared solution needs to be heated in advance to a temperature range of 5 to 55°C and set aside.

5. A TiO2 chemical bath deposition technology for synchronously achieving deposition control and doping according to claim 1, characterized in that: The water bath process described in step (5) has a temperature of 45 to 90° C., a water bath time range of 20 to 90 min, and a deionized water rinse standard when the solution in the sealed container becomes clear.

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