Preparation method of self-assembled small molecule ammonium salt material and application in perovskite solar cell

Abstract

A method for preparing a self-assembled small-molecule ammonium salt material and its application in perovskite solar cells, relating to the field of perovskite photovoltaic technology, wherein the chemical structural formula of the passivation material is: This material, used as a surface passivator for perovskite thin films, improves perovskite crystallization and reduces its susceptibility to humidity. Furthermore, due to its inductive effect, the electron-withdrawing properties of fluorine atoms and carbonyl groups reduce carrier transport losses. In addition, this passivation material is simple to prepare, has high yield, and low cost, making it a high-performance optoelectronic material. When used as a passivation layer in perovskite solar cells, it achieves a photoelectric conversion efficiency exceeding 23.91%.

Description

A method for preparing self-assembled small molecule ammonium salt materials and their application in perovskite solar cells Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and particularly to a method for preparing a small molecule ammonium salt material as a passivation layer and its application in perovskite solar cells. Background Technology

[0002] With the advancement of technology and the continuous improvement of scientific and technological development, the world's demand for energy has increased dramatically, leading to the problem of energy depletion. Simultaneously, environmental pollution has become increasingly serious along with the rapid consumption of energy. To achieve sustainable development, scientists are advocating the use of green, low-carbon, and clean energy, and are therefore actively researching it. Among various green energy sources, solar energy is not limited by geographical conditions or the environment. In recent years, solar photovoltaic products have developed rapidly, giving rise to perovskite solar cells. These cells mainly have advantages such as low cost and high efficiency. However, they still experience some energy loss, and the crystallinity of perovskite is affected by humidity. Therefore, addressing these shortcomings and striving to improve them, a simple, stable, and mass-producible small-molecule ammonium salt material suitable as a passivation layer has been developed for use in perovskite solar cells, which is of practical significance. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the current technology of perovskite solar cells by providing an ammonium salt type monomolecular film as a material for passivating surface defects in the cell, and also providing a method for preparing this material and its application in perovskite solar cells.

[0004] In the method of this invention, due to the inductive effect, the electron-withdrawing properties of fluorine atoms and carbonyl groups reduce carrier transport losses. Furthermore, the hydrophobic properties of fluorine atoms allow for better crystallization of the perovskite layer, reducing the impact of humidity on battery performance. This passivation material preparation method is simple, has a high yield, and low preparation cost, making it a high-performance optoelectronic material.

[0005] The technical solution adopted in this invention is:

[0006] The first aspect of this invention aims to provide a self-assembled small molecule ammonium salt material having the chemical structural formula X-DF:

[0007]

[0008] A second aspect of this invention provides a method for preparing the above-described X-DF compound, comprising the following steps:

[0009] S1: Couples compound 1 with compound 2 to generate intermediate 3;

[0010]

[0011] S2: Causes compound 3 to directly desorb Boc (tert-butyloxycarbonyl) to become an ammonium salt, generating the final product X-DF;

[0012]

[0013] Further, in S1, compound 1 is dissolved in Tol (toluene), and then tetrakis(triphenylphosphine)palladium (0.045M) catalyst and potassium carbonate aqueous solution (5M) are added. After waiting for 10 min to react, ethanol in proportion to water is added to the solution, and the mixture is heated to 100-110°C, preferably to 100°C, and reacted for 6-8 h to obtain compound 2. The amount of the compounds involved in the reaction is calculated according to the molar ratio of compound 1 to compound 2 as 1:1.5.

[0014] Further, in S2, compound 3 is completely dissolved with Dio(1,4-dioxane), and then 55% hydroiodic acid is gradually added dropwise under a nitrogen atmosphere. The reaction is carried out at 40°C in the dark for 6-8 hours, preferably 8 hours, to obtain crude product X-DF. After the reaction is completed, crude product X-DF is filtered and crystallized twice or more (concentrated crystallization). The molar ratio of compound 3 to 55% hydroiodic acid is 1:2.

[0015] A third aspect of this invention is to provide the application of the self-assembled small molecule ammonium salt material of this invention as a passivation layer in perovskite solar cells.

[0016] The beneficial effects of this invention are: 1. The small molecule ammonium salt material passivator provided by this invention, with its electron-withdrawing properties of fluorine atoms and carbonyl groups, strengthens intermolecular interactions, makes charge carriers more active, and reduces losses; simultaneously, the hydrophobicity of fluorine atoms improves perovskite crystallization, reducing the contact between perovskite and water, thus making the battery more stable and performing better. 2. The application of the hole transport material provided by this invention in perovskite solar cells, as shown in Figure 3, demonstrates that the short-circuit photocurrent density of the battery device reaches 23.13 mA cm⁻¹. -2 The open-circuit voltage is 1.19V, the fill factor is 0.77, and the photoelectric conversion efficiency reaches 23.91%, which is of practical significance for improving the efficiency of perovskite solar cells. 3. The passivating agent material described in this invention has a simple synthesis route, excellent yield, readily available raw materials, and high stability. This ammonium salt small molecule material is a very promising passivating material that can also be used for doping. Attached Figure Description

[0017] Figure 1 shows the NMR spectrum of the X-DF prepared according to the present invention;

[0018] Figure 2 shows the JV curves of the inverted perovskite solar cell prepared by X-DF as the passivation layer material according to the present invention compared with the standard.

[0019] Figure 3 shows the IPCE diagram of the X-DF prepared according to the present invention;

[0020] Figure 4 is a comparison diagram of the UV-Vis of the X-DF prepared in this invention and the standard specimen;

[0021] Figure 5 shows a comparative test diagram of the water contact angle of the X-DF prepared in this invention;

[0022] Figure 6 is a schematic diagram of the structure of the inverted perovskite solar cell fabricated in Example 1. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments thereof. 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.

[0024] Example 1

[0025] This method synthesizes a self-assembled small molecule ammonium salt passivating agent, whose chemical formula is X-DF.

[0026]

[0027] The specific synthetic route is as follows:

[0028]

[0029] Synthesis of compound 1:

[0030] To a 100 mL double-necked flask, add reactant 1 (0.8 g), reactant 2 (0.67 g), tetrakis(triphenylphosphine)palladium (140 mg), potassium carbonate (1.84 g), water (1.5 mL), and ethanol (2 mL) in sequence. Heat to 100 °C and reflux for 6–8 h. After the reaction mixture cools to room temperature, extract with dichloromethane and water. Rotary evaporate the organic phase. The crude product is subjected to column chromatography (eluent: petroleum ether / dichloromethane = 20 / 1–1 / 2) to give 0.85 g of the compound shown in Formula 2, a white powder, with a yield of 93.4%.

[0031] Synthesis of product X-DF from Formula 2:

[0032] Under nitrogen protection, intermediate 3 (0.85 g) was added sequentially to a 100 mL two-necked flask and completely dissolved with Dio (1,4-dioxane). Then, 55% hydroiodic acid (0.68 mL) was gradually added dropwise. The reaction mixture was heated to 40 °C and reacted for 6-8 h in the dark. After cooling to room temperature, ethanol was added and the solid was rotary evaporated. Filtration and crystallization were then performed to obtain 0.74 g of the product as a pale yellow powder, with a yield of 80.7%.

[0033] The structural characterization data of compound formula 3 are as follows: 1 H NMR (400MHz, DMSO-d6) δ10.28(s,1H),8.10–8.07(m,1H),8.05(dd,J=8.2,2.9Hz,1H),7.79(s,3H),7.70(d, J=8.2Hz,2H),7.52(dd,J=10.5,8.5Hz,1H),7.40(d,J=8.2Hz,2H),3.11(d,J=9.2Hz,2H),2.94–2.89(m,2H).

[0034] In this embodiment, the overall yield of the X-DF compound synthesized through a two-step continuous reaction was 80.7%.

[0035] Example 2

[0036] In this embodiment, a small-molecule ammonium salt material was prepared as a passivation layer, and its 1H NMR spectrum is shown in Figure 1. Simultaneously, the UV-Vis spectrum of this molecule is significantly higher than the standard control, indicating that the fluorine atoms in the molecule enhance the crystallinity of the perovskite (Figure 4). Compared with the standard ITO perovskite film, the ITO perovskite film with added X-DF passivation material showed a significant increase in water contact angle (Figure 5), indicating that the film formed by this molecule can better shield external moisture, allowing the perovskite to crystallize more fully.

[0037] This embodiment provides an application of the X-DF compound prepared in Example 1 in the fabrication of perovskite solar cells. Figure 6 shows a schematic diagram of the fabricated perovskite solar cell. The test light source was AM 1.5 (solarsimulator-Oriel 91160-1000, 300W), and data acquisition was performed using a Keithley 2400 digital source meter. The test results are shown in Figure 2; the short-circuit photocurrent density of the solar cell reached 23.13 mA cm⁻¹. -2The open-circuit voltage is 1.19V, the fill factor (FF) is 0.77, and the photoelectric conversion efficiency reaches 23.91%. Simultaneously, this molecule has a strong ability to capture photons, exhibiting a monochromatic electro-electric conversion efficiency of over 80% in the 350-800nm ​​wavelength range, enabling it to convert most solar energy into electrical energy (as shown in Figure 3).

[0038] It should be further noted that the above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A self-assembled small molecule ammonium salt material, characterized in that: The material has the chemical structural formula X-DF: 。 2. The method for preparing the self-assembled small molecule ammonium salt material according to claim 1, characterized in that... The steps include: S1: coupling compound 1 with compound 2 to generate intermediate 3; S2: Directly removes the tert-butyloxycarbonyl group (Boc) from compound 3 to form an ammonium salt, generating the final product X-DF; 。 3. The method for preparing self-assembled small molecule ammonium salt materials according to claim 2, characterized in that: Step S1 involves coupling compound 2, which contains boric acid groups, and compound 1, which contains bromine atoms, using toluene as a solvent and reacting at 100°C for 6-8 h to obtain compound 3.

4. The method for preparing self-assembled small molecule ammonium salt materials according to claim 3, characterized in that: The molar ratio of compound 1 to compound 2 is 1:1.

5.

5. The method for preparing self-assembled small molecule ammonium salt materials according to claim 2, characterized in that: Step S2 involves dissolving compound 3 completely under a nitrogen atmosphere using 1,4-dioxane Dio as a solvent in the dark, and then gradually adding 1.5 to 2 equivalents of hydroiodic acid at 40 °C for 8 h.

6. The method for preparing self-assembled small molecule ammonium salt materials according to claim 5, characterized in that: The molar ratio of compound 3 to hydroiodic acid is 1:

2.

7. The method for preparing self-assembled small molecule ammonium salt materials according to claim 2, characterized in that: After the reaction is complete, two or more crystallizations are required, and the crystallization is concentrated crystallization.

8. The application of the self-assembled small molecule ammonium salt material as a passivation layer in perovskite solar cells according to claim 1.

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