A preparation method of a hole transport material suitable for a perovskite solar cell

Abstract

A method for preparing hole transport materials suitable for perovskite solar cells is disclosed. This method involves preparing the organic small-molecule hole transport material XLGT-6 for perovskite solar cell production. XLGT-6 can be used alone as a hole transport layer in perovskite solar cells, or as an interface modification layer. XLGT-6 can be used to prepare perovskite solar cell thin films as hole transport materials via solution processing or thermal evaporation, without the need for doping. The preparation method specifically includes two steps: the synthesis of compound one and the synthesis of compound XLGT-6. This invention has the advantages of simple synthesis and low cost. Thin films can be prepared via solution processing or thermal evaporation, and it has the advantage of not requiring doping. When applied to perovskite solar cells, its photophysical properties, such as light absorption, energy levels, crystallinity, and film formation, can be controlled through chemical modification of the molecular structure, thereby improving the power generation efficiency of perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the technical field of perovskite solar cell fabrication methods, and in particular to a method for preparing hole transport materials suitable for perovskite solar cells. Background Technology

[0002] Perovskite solar cells are solar cells that utilize perovskite-type organometal halide semiconductors as light-absorbing materials. They belong to the third generation of solar cells and are also known as new-concept solar cells. Compared to ordinary silicon solar cells, perovskite solar cells are increasingly widely used due to their high power generation efficiency and long lifespan, showing great development prospects. Perovskite solar cells consist of two organic materials: a semiconductor material called perovskite and an organic dye. When sunlight shines on the perovskite surface, electrons are excited and jump to electron-hole pairs in the organic dye. These electron-hole pairs send current in the circuit, generating electrical energy, thus achieving the conversion of solar energy into electrical energy. The working principle of perovskite solar cells can be simply described as follows: when sunlight shines on the perovskite, an external electric field is generated, causing electrons and holes in the perovskite to disperse. Electrons are released from the perovskite and then attracted by holes in the organic dye, converting them into electrical energy.

[0003] In existing technologies, hole transport materials used in the production of perovskite solar cells (PVSCs) mainly include polymers such as PEDOT:PSS (poly(3,4-ethylenedioxythiophene / polystyrene sulfonic acid)) and PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), as well as inorganic metal oxides such as nickel oxide. Although PEDOT:PSS has high conductivity and good light transmittance, its work function does not match the perovskite energy levels well, resulting in significant energy loss at the perovskite / PEDOT:PSS interface, leading to low photoelectric conversion efficiency in PVSCs using PEDOT:PSS as the hole transport layer. PTAA has suitable energy levels and good hole transport capabilities; however, its hydrophobicity results in poor wettability to polar perovskite precursor solutions, often requiring pretreatment such as doping, solvent washing, or the introduction of an interface layer. While these methods can achieve excellent device performance, they also increase the complexity of the device fabrication process. Nickel oxide has low hole transport efficiency, which leads to severe charge recombination at the NiO / perovskite interface. Therefore, it is often necessary to improve its band arrangement through doping, which limits its practical application. Summary of the Invention

[0004] To overcome the shortcomings of existing perovskite solar cell production, where the hole transport materials used have structural limitations that result in the finished cells exhibiting the drawbacks described in the background, this invention provides a method for preparing hole transport materials suitable for perovskite solar cells. This method, through the application of relevant materials and preparation processes, offers advantages such as a relatively simple synthesis process and low cost. The hole transport materials prepared can be used to prepare perovskite solar cell thin films via solution methods (such as spin coating, spraying, blade coating, and coating) or thermal evaporation (vapor deposition). Furthermore, it has the advantage of not requiring doping. This method provides strong technical support for improving the quality of perovskite solar cell products.

[0005] The technical solution adopted by this invention to solve its technical problem is: A method for preparing a hole transport material suitable for perovskite solar cells is characterized by the preparation of an organic small molecule hole transport material XLGT-6 for perovskite solar cell production. The prepared XLGT-6 can be used alone as a hole transport layer in perovskite solar cells, or as an interface modification layer to modify the material for hole transport. XLGT-6 can be used to prepare perovskite solar cell thin films as hole transport materials via solution method or thermal evaporation, without doping. The preparation method specifically includes two steps: the synthesis of compound one and the synthesis of compound XLGT-6. The synthesis of compound one specifically employs the Knoevenagel condensation method, including the following steps: S1: First, weigh 2,5-dibromoterephthalic acid and 2-[4-(trifluoromethyl)phenyl]acetonitrile and add them to a flask equipped with a magnetic stir bar. Under argon gas injection, inject ultra-dry ethanol and stir the reaction. Then, add NaOH dissolved in ultra-dry anhydrous ethanol dropwise to the flask until the color changes; S2: Stir with a stirrer until a precipitate forms, filter under reduced pressure to precipitate the solid, and... After washing repeatedly with water and ethanol, compound one, a yellow product, was obtained; S3: The structure of compound one was identified by 1H NMR spectroscopy; The synthesis of compound XLGT-6 includes the following steps: SA1: Compound one and 4-boronate-4',4'-dimethoxytriphenylamine were weighed and placed in a dry Schlenk tube. Tetra(triphenylphosphine)palladium (Pd(pph3)4) was weighed in a glove box. Under argon protection, ultra-dry tetrahydrofuran and K2CO3 solution were added to the Schlenk tube by stirring under argon. Stir for a period of time; SA2: After the product of SA1 is stirred until the reaction is complete, cool and quench the reaction with water, then extract with dichloromethane and dry on anhydrous sodium sulfate; SA3: Remove the excess solvent from step SA2 with a rotary evaporator, and purify the residue by column chromatography using petroleum ether and dichloromethane as eluents. After purification, an orange solid compound XLGT-6 is obtained; SA4: The structure of compound XLGT-6 is identified by 1H NMR spectroscopy, and the 1H NMR spectrum, 1C NMR spectrum, and high-resolution mass spectrometry data of compound XLGT-6 are obtained.

[0006] Further, in step S1, the amount of 2,5-dibromoterephthalic acid used is 150 mg and the concentration is 0.51 mmol, the amount of 2-[4-(trifluoromethyl)phenyl]acetonitrile used is 190.1 mg and the concentration is 1.03 mmol, the flask is a 100 ml flask, and the amount of ultra-dry ethanol used is 20 ml.

[0007] Furthermore, in step S2, the stirring process is carried out at room temperature for 6 hours to obtain a yellow product compound with a weight of 298 mg and a yield of 93%.

[0008] Further, in step SA1, the following were weighed: 129.6 mg of compound 1 with a concentration of 0.21 mmol; 224 mg of 4-boronate-4',4'-dimethoxytriphenylamine with a concentration of 0.52 mmol; 24 mg of tetra(triphenylphosphine)palladium (Pd(pph3)4) with a concentration of 0.02 mmol; 10 mL of tetrahydrofuran; and 2 mL of K2CO3 with a concentration of 2 mol / L. The mixture was stirred at 85°C under argon atmosphere for 12 h.

[0009] Furthermore, in step SA3, the ratio of petroleum ether to dichloromethane is 2:1, and the purified orange solid compound XLGT-6 weighs 169 mg with a yield of 75%.

[0010] Compared with existing technologies, the beneficial effects of this invention are as follows: The novel material compound XLGT-6 prepared by this invention is mainly suitable for perovskite solar cells, especially pin perovskite solar cells and crystalline silicon-perovskite tandem solar cells. It can be used alone as a hole transport layer or as an interface modification layer to modify hole transport materials such as NiOX, PTAA, and PEDOT:PSS. When used as a hole transport material in perovskite solar cells, it has the advantages of simple synthesis and low cost. Thin films can be prepared by solution methods (such as spin coating, spraying, blade coating, etc.) or by thermal evaporation (vapor deposition), and it has the advantage of not requiring doping. When applied to perovskite solar cells, its photophysical properties such as light absorption, energy levels, crystallinity, and film formation can be controlled through chemical modification of the molecular structure, thereby improving the power generation efficiency of perovskite solar cells. In summary, this invention has good application prospects. Attached Figure Description

[0011] Figure 1 This is the molecular structural diagram of the compound XLGT-6 prepared in this invention.

[0012] Figure 2 This is a diagram illustrating the synthesis process of the compound XLGT-6 prepared in this invention.

[0013] Figure 3 This is the 1H NMR spectrum of the compound XLGT-6 of this invention in CDCl3.

[0014] Figure 4 This is the 13C NMR spectrum of the compound XLGT-6 of this invention in CDCl3.

[0015] Figure 5 This is a high-resolution mass spectrum of the compound XLGT-6 of this invention.

[0016] Figure 6This is a JV curve of an inverted perovskite solar cell using the compound XLGT-6 of this invention as a hole transport material.

[0017] Figure 7 This is a schematic diagram showing the average efficiency of 20 inverted perovskite solar cells using the compound XLGT-6 of this invention as a hole transport material. Detailed Implementation

[0018] Figure 1 , 2 As shown, a method for preparing hole transport materials suitable for perovskite solar cells is presented. This method involves preparing the organic small-molecule hole transport material XLGT-6 for perovskite solar cell production. XLGT-6 can be used alone as a hole transport layer (XLGT-6 is primarily suitable for perovskite solar cells, especially PIN perovskite solar cells and crystalline silicon-perovskite tandem solar cells; it can be used alone as a hole transport layer, or as an interface modification layer (such as NiOX, PTAA, PEDOT:PSS, etc.). XLGT-6 can be prepared into perovskite solar panel thin films using solution methods (such as spin coating, spraying, blade coating, etc.) and thermal evaporation (vapor deposition), without the need for doping. The preparation and synthesis process is relatively simple. Its photophysical properties, such as light absorption, energy levels, crystallinity, and film formation, can be controlled through chemical modification of the molecular structure, making it increasingly popular. The preparation process of compound XLGT-6 has the advantages of simple synthesis and low cost.

[0019] Figure 1 , 2As shown, a method for preparing hole transport materials suitable for perovskite solar cells is specifically included in the synthesis of compound one and the synthesis of compound XLGT-6. In the synthesis of compound one, the Knoevenagel condensation method is used to synthesize the required compound one, specifically including the following sub-steps: (1): Weigh 2,5-dibromoterephthalic acid (150 mg, 0.51 mmol) and 2-[4-(trifluoromethyl)phenyl]acetonitrile (190.1 mg, 1.03 mmol) and add them to a 100 ml round-bottom flask with a magnetic flask (a commonly used experimental instrument for organic reactions). Under the condition that argon gas is introduced into the flask (this reaction is sensitive to water and oxygen and needs to be carried out under anhydrous and oxygen-free conditions, argon gas plays a protective role and is a routine operation in organic synthesis), first inject 20 The reaction was stirred with an electric stirrer using 1 ml of ultra-dry ethanol (this reaction is sensitive to water and oxygen and requires anhydrous and oxygen-free conditions; ordinary anhydrous ethanol contains a small amount of water, so ultra-dry ethanol must be used, which is a routine operation in organic synthesis). Then, NaOH dissolved in ultra-dry anhydrous ethanol (this reaction must be carried out under alkaline conditions) was slowly added dropwise to the round-bottom flask until it changed color. After stirring for another 6 hours at room temperature, a precipitate formed in the flask. The solid was filtered out under reduced pressure (reduced pressure filtration, a routine operation in organic synthesis) and washed repeatedly with water and ethanol to obtain 298 mg of yellow compound (yield 93%). (2): The 1H NMR spectrum of compound 1 obtained in step (1) was identified using a 600 MHz, deuterium-based CDCl3 δ8.39 (s, 2H), 7.86 (s, 2H), 7.85 (d, J = 4.5 Hz, 4H), 7.77 (d, J = 8.3 Hz, 4H) instrument (this step proves that the product obtained is compound 1).

[0020] Figure 1 , 2 As shown, a method for preparing hole transport materials suitable for perovskite solar cells, including the synthesis of compound XLGT-6. The steps are as follows: (1): Weigh compound 1 (129.6 mg, 0.21 mmol) and 4-boronate-4',4'-dimethoxytriphenylamine (224 mg, 0.52 mmol) into a dry Schlenk tube (similar to a flask, a reaction tube used in organic synthesis). In a glove box (a device that provides an inert gas atmosphere), weigh tetra(triphenylphosphine)palladium (Pd(pph3)4 (24 mg, 0.02 mmol). Under the protection of argon gas (this reaction is sensitive to oxygen and needs to be carried out under anaerobic conditions; argon gas plays a protective role and is a routine operation in organic synthesis), add 10 mL of ultra-dry tetrahydrofuran and 2 mL of K2CO3. (Potassium carbonate, concentration 2 mol / L) solution was placed in a Schlenk tube (tetrahydrofuran is the reaction solvent, potassium carbonate is the reaction solvent, this reaction is called Suzuki coupling reaction, which needs to be carried out under alkaline conditions), stirred with an electric stirrer for 12 h in argon at 85℃, cooled and quenched with water after the reaction was complete (a common expression for describing the experimental steps of organic synthesis, meaning to stop the reaction), and then extracted with dichloromethane as the extraction material, and dried with anhydrous sodium sulfate (used to dry and remove water). (2): The excess solvent in the reaction tube was removed by an electric rotary evaporator, and the residue in the reaction tube was purified by column chromatography (column chromatography is one of the organic extraction methods). Petroleum ether and dichloromethane were used as purification materials, and the specific ratio of petroleum ether to dichloromethane was 2:1 (v / v) as the eluent. After purification, 169 mg of orange solid, namely XLGT-6 material, was obtained, with a yield of 75%.(3): ¹H NMR (600 MHz, deuterium-based CDCl₃) was used for spectral analysis: δ 8.24 (s, 2H), 7.72 (d, J = 7.4 Hz, 6H), 7.69 (d, J = 8.4 Hz, 4H), 7.26 (d, J = 5.8 Hz, 4H), 7.13 (d, J = 8.8 Hz, 8H), 6.98 (d, J = 8.6 Hz, 4H), 6.86 (d, J = 8.9 Hz, 8H), 3.80 (s, 12H). ¹³C NMR (151 MHz, deuterium-based CDCl₃) was used for spectral analysis: δ 156.47, 149.16, 143.87, 141.09, 140.17, 137.52, 133.08, 131.24, 130.78, 130.30, 129.48, 127.27, 126.41, 126.15, 119.03, 117.55, 114.89, 111.93, 55.51. High-resolution mass spectrometry (HRMS) [M+H]+ for C66H48F6N4O4 m / z:calcd 1075.3652; found 1075.3645) was used to identify the XLGT-6 material obtained in step (3) by its 1H NMR spectrum, 1C NMR spectrum, and high-resolution mass spectrometry results (this step is to prove that the obtained product is XLGT-6).

[0021] Figure 1 The molecular structure of the organic small-molecule hole transport material XLGT-6 is presented. This hole transport material is mainly suitable for perovskite solar cells, especially pin-type perovskite solar cells and crystalline silicon-perovskite tandem solar cells. It can be used alone as a hole transport layer in perovskite solar cells, or as an interface modification layer to modify hole transport materials such as NiOX, PTAA, and PEDOT:PSS. The advantages of the above-mentioned hole transport material are as follows: simple synthesis (both reactions are relatively conventional organic synthesis reactions), low cost (the raw materials are relatively inexpensive, only two reaction steps are needed to obtain the final product, and the reaction yield is high); in the production of perovskite solar cells, thin films can be prepared by solution methods (such as spin coating, spraying, blade coating, coating, etc.) or by thermal evaporation (vapor deposition).

[0022] Figure 3 This is the 1H NMR spectrum of compound XLGT-6 in CDCl3 (this spectrum, combined with proton NMR, carbon NMR, and high-resolution mass spectrometry, can prove that the synthesized compound is XLGT-6). Figure 4This is the 13C NMR spectrum of compound XLGT-6 in CDCl3 (this spectrum, combined with proton NMR, carbon NMR, and high-resolution mass spectrometry, can prove that the synthesized compound is XLGT-6). Figure 5 This is a high-resolution mass spectrum of compound XLGT-6. Specifically, compound XLGT-6 is used as a hole transport material in the performance of inverted perovskite solar cells (inverted is the standard term). The device (inverted perovskite solar cell, device refers to the inverted perovskite solar cell mentioned in the first half of the sentence) has the structure of ITO / XLGT-6 / Perovskite / PEAI / PCBM / BCP / Ag and the device area is 0.0625 cm2. Figure 6 This is a JV curve of an inverted perovskite solar cell using compound XLGT-6 as a hole transport material. Figure 7 This is the average efficiency of 20 inverted perovskite solar cells using compound XLGT-6 as the hole transport material (the image proves that the data is reproducible).

[0023] The table below shows the performance of the compound XLGT-6 as a hole transport material in an inverted perovskite solar cell.

[0024]

[0025] Please analyze, in conjunction with all the technical solutions in this application, why this application achieves good work function matching with perovskite energy levels, low energy loss at the perovskite / PEDOT:PSS interface, high photoelectric conversion efficiency of PVSCs with PEDOT:PSS as the hole transport layer, good wettability to polar perovskite precursor solutions, reduced complexity of device fabrication process, and no need to improve band alignment through doping. Through the above technical solutions, the novel material compound XLGT-6 prepared by this invention is mainly suitable for perovskite solar cells. When used as a hole transport material in perovskite solar cells, it has the advantages of simple synthesis and low cost. Thin films can be prepared by solution method or thermal evaporation, and doping is not required. Furthermore, its application in the fabrication of perovskite solar cells allows for the regulation of its photophysical properties such as light absorption, energy levels, crystallinity, and film formation through chemical modification of the molecular structure, thereby improving the power generation efficiency of perovskite solar cells.

[0026] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. It will be apparent to those skilled in the art that the present invention is limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0027] Furthermore, it should be understood that although this specification describes the embodiments, the embodiments do not necessarily contain only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a hole transport material suitable for perovskite solar cells, characterized in that, The organic small molecule hole transport material XLGT-6 was prepared for use in the production of perovskite solar cells. XLGT-6 can be used alone as a hole transport layer in perovskite solar cells, or as an interface modification layer to modify the material for hole transport. XLGT-6 can be used to prepare perovskite solar cell films as hole transport materials via solution method or thermal evaporation, without doping. The preparation method specifically includes two steps: the synthesis of compound one and the synthesis of compound XLGT-6. The synthesis of compound one specifically employs the Knoevenagel condensation method, including the following steps: S1: First, weigh 2,5-dibromo-terephthalaldehyde and 2-[4-(trifluoromethyl)phenyl]acetonitrile and add them to a flask equipped with a magnetic stir bar. Under argon gas injection, inject ultra-dry ethanol and stir the reaction. Then, add NaOH dissolved in ultra-dry anhydrous ethanol dropwise to the flask until the color changes. S2: Stirring with a stirrer until a precipitate forms, filtering the solid under reduced pressure, and washing repeatedly with water and ethanol to obtain compound one, a yellow product; S3: Structural identification of compound one by 1H NMR spectroscopy; The synthesis of compound XLGT-6 includes the following steps: SA1: Weighing compound one and 4-boronate-4',4'-dimethoxytriphenylamine into a dry Schlenk tube, weighing tetra(triphenylphosphine)palladium in a glove box, adding ultra-dry toluene and K2CO3 solution into the Schlenk tube under argon protection, and stirring with a stirrer for a period of time under argon; SA2: After the product of SA1 is stirred until the reaction is complete, cooling and quenching the reaction with water, then extracting with dichloromethane and drying on anhydrous sodium sulfate; SA3: Removing excess solvent from step SA2 using a rotary evaporator, purifying the residue by column chromatography using petroleum ether and dichloromethane as eluents, and obtaining orange solid compound XLGT-6 after purification; The structure of XLGT-6 is... .

2. The method for preparing a hole transport material suitable for perovskite solar cells according to claim 1, characterized in that, In step S1, the amount of 2,5-dibromo-terephthalaldehyde used is 150 mg, the amount of 2-[4-(trifluoromethyl)phenyl]acetonitrile used is 190.1 mg, the flask is a 100 ml flask, and the amount of ultra-dry ethanol used is 20 ml.

3. The method for preparing a hole transport material suitable for perovskite solar cells according to claim 1, characterized in that, In step S2, the stirring process was carried out at room temperature for 6 hours, yielding a yellow product compound with a weight of 298 mg and a yield of 93%.

4. The method for preparing a hole transport material suitable for perovskite solar cells according to claim 1, characterized in that, In step SA3, the ratio of petroleum ether to dichloromethane is 2:1, and the purified orange solid compound XLGT-6 weighs 169 mg with a yield of 75%.

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