SnO2 nanoparticles and their preparation method and use

Abstract

The present invention discloses a solvothermal method for synthesizing SnO2 nanoparticles in one step. The method comprises adding acetylacetone to isopropyl alcohol as a mixed solvent, adding tin tetrachloride, stirring thoroughly, reacting in a reactor at 180-220°C for 12-24 hours, naturally cooling, separating, washing, and drying to obtain SnO2 nanoparticles. The preparation method of the present invention has the advantages of mild reaction conditions and a simple and easy method. The SnO2 nanoparticles synthesized by the method have broad application prospects in fields such as perovskite solar cells, photocatalysis, and gas sensing.

Description

Technical Field

[0001] The present invention relates to the preparation of inorganic nanomaterials, and in particular to SnO2 nanoparticles and a solvent-thermal preparation method thereof, and their application as an electron transport layer in perovskite solar cells. Background Art

[0002] Over the past decade, organic-inorganic halide perovskite solar cells (PSCs) have attracted widespread attention due to their excellent power conversion efficiencies (PCEs). High-efficiency PSCs have been achieved using nanostructured mesoporous structures, particularly titanium oxide (TiO2). In 2019, researchers from KRICT and MIT reported a 25.2% mesoporous TiO2 PSC. However, TiO2 preparation typically requires high sintering temperatures (450°C), making it nearly impossible to construct mesostructures for flexible devices and tandem applications. Although there have been some reports on low-temperature processing of TiO2, constructing efficient mesostructures at low temperatures remains a challenge. TiO2 is photo-instable, and exposure to light, particularly UV light, negatively impacts device stability. Replacing mesoporous TiO2 structures with other inorganic metal oxides has become a research hotspot. For planar heterojunction PSCs, tin oxide (SnO2) is one of the most suitable candidates to replace TiO2. SnO2 has a deeper conduction band and a wider band gap (3.6-4.1 eV) than TiO2, facilitating electron transport and providing a better ohmic contact. Furthermore, SnO2 has a good band gap match with the perovskite absorber and exhibits higher electron mobility than TiO2. It is foreseeable that developing methods for preparing SnO2 nanomaterials and developing simple, low-temperature synthesis strategies will significantly advance the development of perovskite solar cells. Summary of the Invention

[0003] One of the purposes of the present invention is to provide a solvent-thermal preparation method for SnO2 nanoparticles. The method has one-step synthesis, simple operation, no template, no post-processing, and can quickly synthesize SnO2 nanoparticles under low temperature conditions.

[0004] To achieve the above object, the present invention adopts the following technical solution: a method for preparing SnO2 nanoparticles, comprising the following steps:

[0005] Acetylacetone and isopropyl alcohol are mixed as a mixed solvent, stirred evenly, and then tin salt is added and stirred thoroughly to obtain a mixed solution;

[0006] The mixed solution is transferred to a reactor, reacted at 180-220° C. for 12-24 hours, cooled naturally, centrifuged, washed, and dried to obtain SnO2 nanoparticles.

[0007] As a further improvement of the preparation method of SnO2 nanoparticles:

[0008] Preferably, the acetylacetone and isopropyl alcohol are mixed in a volume ratio of 1:(1-4) as a mixed solvent.

[0009] Preferably, the tin salt is tin tetrachloride.

[0010] Preferably, the amount of the tin salt added to 100 ml of the mixed solvent is 2-20 g.

[0011] Preferably, the washing solvent is anhydrous ethanol, and the drying temperature is 60-100°C.

[0012] The second object of the present invention is to provide SnO2 nanoparticles obtained by the above preparation method.

[0013] As a further improvement of SnO2 nanoparticles:

[0014] Preferably, the size of the SnO2 nanoparticles is 30-50 nm.

[0015] The third object of the present invention is to provide the application of the above-mentioned SnO2 nanoparticles as an electron transport layer in perovskite solar cells.

[0016] The beneficial effects of the present invention compared to the prior art are:

[0017] Compared to existing synthesis techniques, the present invention uses a mixture of two common solvents, acetylacetone and isopropyl alcohol, as a mixed solvent to prepare SnO2 nanoparticles through a simple one-step solvothermal method. This method hydrolyzes tin salts to prepare SnO2 nanomaterials based on the Aldol condensation reaction of ketone compounds under solvothermal conditions. Compared with conventional hydrolysis methods, this method eliminates the need for templates and subsequent treatments, and offers a mild reaction, a simple and easy process, strong controllability, good reproducibility, and high yield. The SnO2 nanoparticles synthesized by the present invention have a wide range of applications in solar cells, gas sensors, photocatalysis, and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a SEM photograph of SnO2 nanoparticles in Example 1 of the present invention.

[0019] Figure 2 This is the JV curve measured for the electron transport layer of a perovskite solar cell in Example 1 of the present invention.

[0020] Figure 3 This is the JV curve measured for the electron transport layer of a perovskite solar cell in Example 2 of the present invention.

[0021] Figure 4This is the JV curve measured for the electron transport layer of a perovskite solar cell in Example 3 of the present invention. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] This embodiment provides a method for preparing SnO2 nanoparticles, which specifically includes the following steps:

[0025] S1. Mix 10 mL of acetylacetone and 40 mL of isopropyl alcohol as a mixed solvent, stir evenly, add 4 g of tin tetrachloride, and stir thoroughly to obtain a mixed solution;

[0026] S2. The mixed solution was transferred to a reactor, reacted at 200° C. for 12 hours, cooled naturally, centrifuged, washed with anhydrous ethanol, and dried at 80° C. to obtain SnO2 nanoparticles.

[0027] The SEM photos of SnO2 nanoparticles prepared in this example are as follows: Figure 1 As shown by Figure 1 It can be seen that the size of the prepared SnO2 nanoparticles is 30-50nm.

[0028] Example 2

[0029] This embodiment provides a method for preparing SnO2 nanoparticles, which specifically includes the following steps:

[0030] S1, 25mL of acetylacetone and 25mL of isopropyl alcohol were mixed as a mixed solvent, stirred evenly, and then 4g of tin tetrachloride was added and stirred thoroughly to obtain a mixed solution;

[0031] S2. The mixed solution was transferred to a reactor, reacted at 200° C. for 12 hours, cooled naturally, and then centrifuged, washed, and dried to obtain SnO2 nanoparticles.

[0032] Example 3

[0033] This embodiment provides a method for preparing SnO2 nanoparticles, which specifically includes the following steps:

[0034] S1, 20mL of acetylacetone and 30mL of isopropyl alcohol were mixed as a mixed solvent, stirred evenly, and then 5g of tin tetrachloride was added, and stirred thoroughly to obtain a mixed solution;

[0035] S2. The mixed solution was transferred to a reactor, reacted at 200° C. for 12 hours, cooled naturally, centrifuged, washed with anhydrous ethanol, and dried at 80° C. to obtain SnO2 nanoparticles.

[0036] Example 4

[0037] This embodiment provides the application of SnO2 nanoparticles in perovskite solar cells:

[0038] The SnO2 nanoparticles prepared in Example 1 were added to a cellulose ethanol solution (5 wt%) at a ratio of 2 wt% to prepare a slurry. The slurry was suspended onto FTO glass as an electron transport material, and then the perovskite material Cs was suspended onto the glass. 0.05 FA 0.95 MA 0.05 A complete perovskite battery device is made through steps such as PbI3, hole transport material spiro-OMeTAD, heating, and gold electrode evaporation.

[0039] The JV curve test results of the battery are as follows Figure 2 As shown. Figure 2 It can be seen that the solar cell device with SnO2 nanoparticles as the electron transport layer exhibits an open circuit voltage of 1.12 V and a current density of 25.13 mA cm -2 The short-circuit current and fill factor of 81.24% were achieved, and finally the photoelectric conversion efficiency of 22.79% was obtained.

[0040] Similarly, referring to the above steps, the SnO2 nanoparticles of Examples 2 and 3 were used to prepare perovskite battery devices. The JV test results of the batteries were as follows: Figure 3 、 Figure 4 As shown in the figure: the solar cell device with SnO2 nanoparticles prepared in Example 2 as the electron transport layer showed an open circuit voltage of 1.11V and a current of 24.6mAcm -2 The short-circuit current and fill factor of 81.75% finally achieved a photoelectric conversion efficiency of 22.41%. The solar cell device with SnO2 nanoparticles as the electron transport layer prepared in Example 3 showed an open circuit voltage of 1.11V and a current of 25.2mAcm -2 The short-circuit current and fill factor of 81.17% were achieved, and finally the photoelectric conversion efficiency of 22.69% was obtained.

[0041] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. Application of SnO2 nanoparticles as an electron transport layer in perovskite solar cells, characterized in that: SnO2 nanoparticles are added to a 5wt% cellulose ethanol solution at a ratio of 2wt% to prepare a slurry, and the slurry is suspended and coated on FTO glass to serve as an electron transport layer. The preparation method of the SnO2 nanoparticles comprises the following steps: S1, acetylacetone and isopropyl alcohol were mixed in a volume ratio of 1: (1-4) as a mixed solvent, stirred evenly, and then tin tetrachloride was added, wherein the amount of tin tetrachloride added to 100 ml of the mixed solvent was 2-20 g, and stirred thoroughly to obtain a mixed solution; S2. The mixed solution is transferred to a reactor, reacted at 180-220° C. for 12-24 hours, cooled naturally, centrifuged, washed, and dried to obtain SnO2 nanoparticles with a size of 30-50 nm.

2. The use of SnO2 nanoparticles according to claim 1 as an electron transport layer in a perovskite solar cell, characterized in that: The washing solvent is anhydrous ethanol, and the drying temperature is 60-100°C.

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