Preparation method of fluorine-doped nickel oxide nanoparticles

Abstract

The invention discloses a preparation method of fluorine-doped nickel oxide nano-particles, and relates to the technical field of solar cells, and the preparation method specifically comprises the following steps: preparing a fluorine-doped nickel oxide precursor by adopting a coprecipitation method, drying by combining a vacuum freeze drying technology, grinding, and calcining at 270 DEG C to finally obtain the fluorine-doped nickel oxide nano-particles. According to the method, a fluorine element is introduced as a lattice doping agent, the inherent low conductivity problem is fundamentally solved, and experimental results show that compared with undoped nickel oxide, the obtained fluorine-doped nickel oxide material has more excellent conductivity, hole extraction efficiency and electron transmission performance, the photoelectric performance of a perovskite solar cell can be remarkably improved, and the performance of the perovskite solar cell is improved. And a new material basis is provided for the application of the material in the field of photoelectric devices.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and specifically to a method for preparing fluorine-doped nickel oxide nanoparticles. Background Technology

[0002] In recent years, perovskite solar cells have made significant progress, moving from the laboratory to the market and gradually achieving industrialization. In perovskite solar cells, the hole transport layer needs to efficiently extract holes from the perovskite layer and prevent electron-hole recombination at the interface; therefore, the hole transport layer plays a crucial role in cell performance. Common hole transport layers in perovskite solar cells are mainly divided into organic transport layers (such as P3HT, PTAA, and PEDOT:PSS) and inorganic transport layers (such as NiOx and CuOx). Organic transport layers, due to their high cost, low hole mobility, and unsuitable energy level arrangement, severely limit the commercial development of perovskite solar cells. In contrast, inorganic transport layers have advantages such as optimal band alignment, low resistivity, environmental stability, and low cost. Among many inorganic oxides, nickel oxide has been widely used due to its low cost, high visible light transmittance, and convenient precursor solution preparation. However, the inherent low conductivity and structural defects of nickel oxide severely limit its practical application; how to effectively improve this problem is currently a key research area. Among various modification methods, ion doping is widely recognized for its ability to efficiently control the photoelectric properties of materials. Currently, although metal ion doping can partially increase the hole concentration of nickel oxide, its improvement on electron transport performance is limited, and it may introduce side effects such as lattice distortion. Research on non-metal ion doping is still in its early stages.

[0003] Based on this, this invention innovatively employs a non-metallic fluorine doping strategy to modify nickel oxide. In this invention, fluorine-doped nickel oxide nanoparticles are prepared using a co-precipitation method, dried using vacuum freeze-drying technology, ground after drying, and finally calcined at 270℃ to obtain fluorine-doped nickel oxide nanoparticles. When applied to perovskite solar cells, experimental results show that, compared with pure nickel oxide, fluorine-doped nickel oxide exhibits superior electron transport performance and higher hole extraction efficiency, providing new possibilities for its application in optoelectronic devices. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing fluorine-doped nickel oxide nanoparticles. This method aims to fundamentally solve the bottleneck problem of nickel oxide's inherent low conductivity by introducing fluorine as an effective lattice dopant and precisely controlling the electronic structure and defect states of nickel oxide.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing fluorine-doped nickel oxide nanoparticles, comprising the following steps: Step (1): Dissolve nickel nitrate hexahydrate and 1%~10% (molar ratio) ammonium fluoride together in deionized water, and continue stirring at room temperature until all precursor salts are completely dissolved to obtain a clear mixed solution; Step (2): Prepare an alkaline solution of 5~10 mol / L; Step (3): Add the alkaline solution from step (2) to the mixed solution from step (1) at a precise flow rate of 5-20 mL / min until the pH of the solution is 10, while applying mechanical stirring at a speed of 600-1000 rpm to generate a precipitate suspension; Step (4): Filter the precipitate suspension generated in step (3) and wash the precipitate with deionized water 3 to 5 times. Step (5): The washed precipitate is freeze-dried under vacuum for 30-50 h; Step (6): Grind the dried powder and then calcine it in a muffle furnace at 270°C for 2 hours to obtain black fluorine-doped nickel oxide nanoparticles.

[0006] Preferably, the alkaline source of the alkaline solution in step (2) is sodium hydroxide.

[0007] Preferably, the alkaline source of the alkaline solution in step (2) is potassium hydroxide.

[0008] Preferably, the alkaline source of the alkaline solution in step (2) is urea.

[0009] Preferably, the alkaline source of the alkaline solution in step (2) is ammonia.

[0010] Preferably, the vacuum freeze-drying temperature range in step (5) is (-50 ℃~0 ℃), and the vacuum degree range in the vacuum freeze-drying is (0 Pa~20 Pa).

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: This method aims to precisely control the electronic structure and defect states of nickel oxide by introducing fluorine as an effective lattice dopant, thereby fundamentally solving the bottleneck problem of its inherent low conductivity. This method is not only simple in process, but also can improve the conductivity of nickel oxide to a level that meets the application requirements of high-efficiency perovskite solar cells and other optoelectronic devices. The resulting fluorine-doped nickel oxide material has better conductivity, hole extraction efficiency and electron transport performance, which can significantly improve the photoelectric performance of perovskite solar cells and provide a new material basis for its application in the field of optoelectronic devices. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing the microstructure and size of the fluorine-doped nickel oxide nanoparticles of the present invention. Figure 2 A diagram showing the effect of preparing a 20 mg / mL aqueous dispersion of the fluorine-doped nickel oxide nanopowder of the present invention. Figure 3 The images show the XRD patterns of pure nano-nickel oxide and fluorine-doped nano-nickel oxide according to the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Example 1: 1. Dissolve nickel nitrate hexahydrate and 5% (molar ratio) ammonium fluoride together in deionized water, and continue stirring at room temperature until all precursor salts are completely dissolved to obtain a clear mixed solution A; 2. Prepare a 2 mol / L potassium hydroxide solution; 3. Add potassium hydroxide solution to the mixed solution A in step (1) at a precise flow rate of 10 mL / min until the pH of the solution is 10, while applying mechanical stirring at a speed of 1000 rpm to generate precipitate suspension B; 4. Filter the precipitate suspension B generated in step (3) and wash the precipitate three times with deionized water. 5. The washed precipitate was freeze-dried at -20℃ / 10 Pa for 30 hours; 6. Grind the dried powder and then calcine it in a muffle furnace at 270°C for 2 hours to obtain black fluorine-doped nickel oxide nanoparticles.

[0015] The fluorine-doped nickel oxide nanoparticles prepared in this case were formulated into a 20 mg / mL aqueous dispersion, and the results were as follows: Figure 2 As shown, the right side is a diagram of the dispersion after 21 days of standing, demonstrating that nickel oxide can be stably dispersed in water. The microstructure and size of fluorine-doped nickel oxide nanoparticles are as follows... Figure 1 As shown, the particle size is 4~10 nm. Figure 3The figures show the XRD patterns of pure nano-nickel oxide and fluorine-doped nano-nickel oxide. As can be seen from the figures, the fluorine-doped nickel oxide nanoparticles prepared in this embodiment are a single cubic phase with no impurity phases. The five diffraction peaks correspond to the (111), (200), (220), (311), and (222) crystal planes, respectively. This indicates that fluorine doping has no effect on the phase structure of nickel oxide. In addition, an increase in the full width at half maximum (FWHM) and a shift of the peak to a higher angle can be observed in the XRD of fluorine-doped nickel oxide, which indicates that fluorine has been successfully doped into the nickel oxide lattice.

[0016] Fluorine-doped nickel oxide nanopowder was applied to perovskite solar cells, and a control group of pure nickel oxide nanoparticle hole transport layer perovskite solar cell devices were fabricated. The results are shown in Table 1. Compared with pure nickel oxide nanoparticles, the device performance based on fluorine-doped nickel oxide was improved, with a current density of 26.20 mA cm⁻², a VOC of 1.16 V, an FF of 81.55, and a PCE of 24.85%.

[0017] Example 2: 1. Dissolve nickel nitrate hexahydrate and 7% (molar ratio) ammonium fluoride together in deionized water, and continue stirring at room temperature until all precursor salts are completely dissolved to obtain a clear mixed solution A; 2. Prepare a 3 mol / L sodium hydroxide solution; 3. Add sodium hydroxide solution to the mixed solution A in step (1) at a precise flow rate of 5 mL / min until the pH of the solution is 10, while applying mechanical stirring at a speed of 800 rpm to generate precipitate suspension B; 4. Filter the precipitate suspension B generated in step (3) and wash the precipitate with deionized water 4 times. 5. The washed precipitate was freeze-dried at -30℃ / 5 Pa for 36 hours; 6. Grind the dried powder and then calcine it in a muffle furnace at 270°C for 2 hours to obtain black fluorine-doped nickel oxide nanoparticles.

[0018] The results of applying fluorine-doped nickel oxide nanopowder to perovskite solar cells are shown in Table 1. The device based on fluorine-doped nickel oxide has a current density of 26.44 mA cm-2, a VOC of 1.16 V, an FF of 82.66, and a PCE of 25.46%.

[0019] Example 3: 1. Dissolve nickel nitrate hexahydrate and 6% (molar ratio) ammonium fluoride together in deionized water, and continue stirring at room temperature until all precursor salts are completely dissolved to obtain a clear mixed solution A; 2. Prepare an 8 mol / L potassium hydroxide solution; 3. Add potassium hydroxide solution to the mixed solution A in step (1) at a precise flow rate of 15 mL / min until the solution pH is 10, while applying mechanical stirring at a speed of 1000 rpm to generate precipitate suspension B; 4. Filter the precipitate suspension B generated in step (3) and wash the precipitate three times with deionized water. 5. The washed precipitate was freeze-dried at -5℃ / 5 Pa for 48 h; 6. Grind the dried powder and then calcine it in a muffle furnace at 270°C for 2 hours to obtain black fluorine-doped nickel oxide nanoparticles.

[0020] The results of applying fluorine-doped nickel oxide nanopowder to perovskite solar cells are shown in Table 1. The device based on fluorine-doped nickel oxide has a current density of 26.50 mA cm-2, a VOC of 1.16 V, an FF of 82.75, and a PCE of 25.43%.

[0021] Example 4: 1. Dissolve nickel nitrate hexahydrate and 9% (molar ratio) ammonium fluoride together in deionized water, and continue stirring at room temperature until all precursor salts are completely dissolved to obtain a clear mixed solution A; 2. Prepare a 10 mol / L potassium hydroxide solution; 3. Add potassium hydroxide solution to the mixed solution A in step (1) at a precise flow rate of 10 mL / min until the pH of the solution is 10, while applying mechanical stirring at a speed of 1000 rpm to generate precipitate suspension B; 4. Filter the precipitate suspension B generated in step (3) and wash the precipitate three times with deionized water. 5. The washed precipitate was freeze-dried at -10℃ / 5 Pa for 48 h. 6. Grind the dried powder and then calcine it in a muffle furnace at 270°C for 2 hours to obtain black fluorine-doped nickel oxide nanoparticles.

[0022] The results of applying fluorine-doped nickel oxide nanopowder to perovskite solar cells are shown in Table 1. The device based on fluorine-doped nickel oxide has a current density of 26.07 mA cm-2, a VOC of 1.15 V, an FF of 83.35, and a PCE of 25.17%.

[0023] Table 1. Battery device parameter table for Examples 1-4 Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing fluorine-doped nickel oxide nanoparticles, characterized by: The method comprises the following steps: Step (1): Dissolve nickel nitrate hexahydrate and 1-10% (molar ratio) ammonium fluoride in deionized water, continuously stir at room temperature until all precursor salts are completely dissolved, and obtain a clear mixed solution; Step (2): Prepare a 5-10 mol / L alkaline solution; Step (3): Add the alkaline solution in step (2) to the mixed solution in step (1) at a precise flow rate of 5-20 mL / min, add to the solution pH 10, and apply mechanical stirring at a speed of 600-1000 rpm to generate a precipitate suspension; Step (4): Filter the precipitate suspension generated in step (3), and wash the precipitate with deionized water for 3-5 times; Step (5): Vacuum freeze-dry the washed precipitate for 30-50 h; Step (6): Grind the dried powder, and finally place the powder in a muffle furnace for calcination at 270°C for 2 h to obtain black fluorine-doped nickel oxide nanopowder.

2. The method for preparing fluorine-doped nickel oxide nanoparticles according to claim 1, characterized in that: The alkali source of the alkaline solution in step (2) is sodium hydroxide.

3. The method for preparing fluorine-doped nickel oxide nanoparticles according to claim 1, characterized in that: The alkali source of the alkaline solution in step (2) is potassium hydroxide.

4. The method for preparing fluorine-doped nickel oxide nanoparticles according to claim 1, characterized in that: The alkali source of the alkaline solution in step (2) is urea.

5. The method for preparing fluorine-doped nickel oxide nanoparticles according to claim 1, characterized in that: The alkali source of the alkaline solution in step (2) is ammonia.

6. The method for preparing fluorine-doped nickel oxide nanoparticles according to claim 1, characterized in that: The vacuum freeze-drying temperature in step (5) ranges from (-50°C to 0°C), and the vacuum freeze-drying vacuum degree ranges from (0 Pa to 20 Pa).

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