Methylamine bis(trifluoromethanesulfonyl)imide compound structure, preparation method and application thereof

Abstract

The present invention provides a methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) compound and a preparation method thereof. The chemical formula of the compound is C3H6F e N2O4S2 or CH3NH3N(CF3SO2)2, with a molecular weight of 312.2g / mol, and the general structural formula of the compound is shown in the attached figure (the same compound, two different structural expressions). There are two preparation methods, both of which react completely within 20 minutes at room temperature. The compound is a white crystal or powder and does not contain active alkali metal elements such as Li contained in inorganic bis(trifluoromethanesulfonyl)imide salts such as commonly used solar cell charge transport layer additives (LiTSFI, NaTSFI, KTSFI, AgTSFI). + 、Na + , K + 、Ag + , with advantages such as chemical inertness, environmental friendliness, abundant raw materials, adjustable size, good crystallinity, and high mobility. This preparation method is simple, convenient, and reproducible, which is conducive to large-scale industrial preparation and can be used as a charge transport layer material in solar cells.

Description

Technical Field

[0001] The present invention relates to a methylamine bis(trifluoromethanesulfonyl)imide compound structure, a preparation method and an application thereof. Background Art

[0002] Bistrifluoromethanesulfonimide (TSFI) salt compounds are a class of excellent charge transport layer additives for solar cells. - The special chemical structure of the cations has high electrochemical stability and conductivity; and the cations are mostly active alkali metals such as Li + 、Na + , K + 、Ag + Etc., there are moisture absorption and instability: Compared with known inorganic bis(trifluoromethanesulfonyl)imide salts such as LiTSFI, NaTSFI, KTSFI, and AgTSFI, the methylamine bis(trifluoromethanesulfonyl)imide compound (MATSFI) based on methylamine (MA) cation has not been reported yet, and it has the advantages of 1) improving charge extraction of the photovoltaic layer; 2) stabilizing the photovoltaic layer interface; 3) enhancing charge transfer performance; 4) inhibiting water and oxygen corrosion; 5) improving high-temperature stability; 6) improving photoelectric conversion efficiency. Therefore, the development of a methylamine bis(trifluoromethanesulfonyl)imide compound with chemical inertness, high reproducibility, simple synthesis, environmental friendliness, and high mobility to achieve solar cells with high photoelectric conversion efficiency is an urgent market demand and also of great significance in the field of this technology. It is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0003] The present invention provides a methylamine bistrifluoromethanesulfonimide (MATSFI) compound, characterized by a chemical formula of C3H6F6N2O4S2 or CH3NH3N(CF3SO2)2, a molecular weight of 312.2 g / mol, and a general structural formula of the compound as shown in the accompanying drawings (two different structural expressions for the same compound).

[0004] The specific technical scheme is as follows: The preparation method of methylamine bis(trifluoromethanesulfonyl imide) comprises the following steps:

[0005] A methylamine solution (CAS No. 74-89-5) and bis(trifluoromethanesulfonyl imide) (CAS No. 82113-65-3) are dissolved in a solvent respectively, and the two solutions are slowly mixed under stirring at room temperature. The reaction is terminated when the two raw materials are mixed in an equal stoichiometric ratio (molar ratio of 1:1). The solvent in the solution after the reaction is completely distilled off by reduced pressure distillation to obtain the target crude product. The methylamine bis(trifluoromethanesulfonyl imide) compound with a purity of up to 99.9% is prepared by low-temperature recrystallization.

[0006] Methylamine halide and silver bis(trifluoromethanesulfonyl imide) (CAS No. 189114-61-2) are dissolved in solvents respectively, and the two solutions are slowly mixed under stirring at room temperature. The reaction is terminated when the two raw materials are mixed in an equal stoichiometric ratio (molar ratio of 1:1). The by-product silver halide precipitate obtained by the reaction is filtered out, and the solvent in the reaction solution is completely distilled off by vacuum distillation to obtain the target crude product. The product is then recrystallized at low temperature to prepare a methylamine bis(trifluoromethanesulfonyl imide) compound with a purity of up to 99.9%.

[0007] As a preferred embodiment, in the method for preparing methylamine bis(trifluoromethanesulfonyl)imide described in

[0005] , the solvent in the methylamine solution is a solvent that can be easily distilled off by reduced pressure, such as water, alcohols, ketones, ethers, lipids, benzene, etc.

[0008] As a preferred embodiment, in the preparation method of methylamine bis(trifluoromethanesulfonyl)imide described in

[0006] , the methylamine halide is methylamine chloride (CAS No. 593-51-1), methylamine bromide (CAS No. 6876-37-5), or methylamine iodide (CAS No. 14965-49-2).

[0009] As a preferred embodiment, in the preparation method of methylamine bis(trifluoromethanesulfonyl)imide described in

[0006] , the solvent is a solvent that does not dissolve the silver halide precipitate, such as water, alcohols, ketones, ethers, lipids, benzene, etc.

[0010] As a preferred embodiment, in the preparation method of methylamine bis(trifluoromethanesulfonyl imide) described in

[0005] , the amounts of trifluoromethanesulfonyl imide and methylamine solution are in an equal stoichiometric ratio (molar ratio of 1:1) to ensure that only the target product and the solvent are produced after the reaction, and to ensure that all the solvent can be evaporated by reduced pressure distillation, thereby improving the yield.

[0011] As a preferred embodiment, in the preparation method of methylamine bis(trifluoromethanesulfonyl)imide described in

[0006] , the amounts of silver bis(trifluoromethanesulfonyl)imide and methylamine halide are in an equal stoichiometric ratio (molar ratio of 1:1) to ensure that only the target product and the by-product silver halide are precipitated after the reaction, and to ensure that all by-products can be removed by filtration and all solvents can be evaporated by vacuum distillation, thereby improving the yield.

[0012] As a preferred embodiment, the preparation method of methylamine bis(trifluoromethanesulfonyl)imide described in

[0005] has the following reaction formula:

[0013]

[0014] As a preferred embodiment, the preparation method of methylamine bis(trifluoromethanesulfonyl)imide described in

[0006] has the following reaction formula:

[0015]

[0016] In one embodiment, the methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) is a single crystal or powder.

[0017] The above-mentioned methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) does not contain active alkali metal elements and has the advantages of being chemically inert, environmentally friendly, having abundant raw materials, adjustable size, good crystallinity, and high mobility.

[0018] The present invention also provides the use of the methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) in the preparation of solar cells.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention discloses a methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) and its preparation method and application. The bis(trifluoromethanesulfonyl)imide salt does not contain active alkali metal elements such as Li contained in inorganic bis(trifluoromethanesulfonyl)imide salts such as common solar cell charge transport layer additives (LiTSFI, NaTSFI, KTSFI, AgTSFI). + 、Na + , K + 、Ag + , with advantages such as chemical inertness, environmental friendliness, abundant raw materials, adjustable size, good crystallinity, and high mobility. This preparation method is simple, convenient, and reproducible, which is conducive to large-scale industrial preparation and can be used as a charge transport layer material in solar cells.

[0021] Therefore, after a large number of experiments, the inventors selected the methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) with 2,2″,7,7″-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD) and 4-tert-butylpyridine (t-BP), doped and mixed them in proportion, and applied them as charge transport layer materials in solar cells.

[0022] In one embodiment, the molar ratio of methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) to 2,2″,7,7″-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD) is 1:0.1 to 1:100; and the molar ratio of methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) to 4-tert-butylpyridine (t-BP) is 1:0.1 to 1:10. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the general structural formula of the methylamine bistrifluoromethanesulfonimide (MATSFI) compound of the present invention (the same compound has two different structural expressions).

[0024] Figure 2 This is a melting point test chart of purified MATSFII in Example 3 of the present invention.

[0025] Figure 3 The purified MATSFI of Example 3 of the present invention 1 H NMR (DMSO) spectrum.

[0026] Figure 4 The purified MATSFI of Example 3 of the present invention 19 F NMR (DMSO) spectrum.

[0027] Figure 5 The purified MATSFI of Example 3 of the present invention 13 C NMR (DMSO) spectrum.

[0028] Figure 6 This is the differential scanning calorimetry (DSC) test curve of the purified MATSFI in Example 3 of the present invention.

[0029] Figure 7 This is a thermogravimetric analyzer (TGA) test curve of the purified MATSFI in Example 3 of the present invention.

[0030] Figure 8 3 is a scanning electron microscope (SEM) photograph of the top surface of the solar cell before and after coating with MATSFI as the charge transport layer material according to Example 4 of the present invention.

[0031] Figure 9 3 is a scanning electron microscope (SEM) photograph of a cross section of a solar cell before and after coating with MATSFI as a charge transport layer material according to Example 4 of the present invention.

[0032] Figure 101 is a charge mobility curve measured by space charge limited current method (SCLC) using MATSFI of Example 4 of the present invention as a charge transport layer material.

[0033] Figure 11 It is the work function of MATSFI in Example 4 of the present invention as the charge transport layer material measured by ultraviolet photoelectron spectroscopy (UPS).

[0034] Figure 12 This is the voltage-current (JV) curve measured for the solar cell using MATSFI as the charge transport layer material according to Example 4 of the present invention. DETAILED DESCRIPTION

[0035] The essential features and advantages of the present invention are further described below with reference to examples, but the present invention is not limited to the examples listed.

[0036] Example 1

[0037] Synthesis of methylamine bis(trifluoromethanesulfonyl imide).

[0038] In a reactor equipped with a stirrer, 281 g (1 mol, 99% purity) of bistrifluoromethanesulfonyl imide (CAS No. 82113-65-3) and 500 mL of anhydrous ethanol were added. After the raw materials were completely dissolved, 1 mol of methylamine solution (33% ethanol solution) was slowly added to the reactor while maintaining the reaction temperature at room temperature (25±10°C). The reaction was stirred at room temperature for 1 hour to complete. After the reaction, the ethanol solvent in the solution was completely distilled off under reduced pressure and vacuum dried at 60°C to obtain crude methylamine bistrifluoromethanesulfonyl imide as white crystals with a yield of no less than 95%.

[0039] Example 2

[0040] Synthesis of methylamine bis(trifluoromethanesulfonyl imide).

[0041] In a reactor equipped with an agitator, 38.8 g (0.1 mol, 99% purity) of silver bis(trifluoromethanesulfonyl)imide (CAS No. 189114-61-2) and 200 mL of anhydrous ethanol were added. After the raw materials were completely dissolved, the reaction temperature was maintained at room temperature (25±10°C). 50 mL of anhydrous ethanol solution containing 15.9 g (0.1 mol, 99% purity) of methylamine iodide (CAS No. 14965-49-2) was slowly added to the reactor. The reaction was stirred at room temperature for 1 hour to complete the reaction. The silver iodide precipitate produced by the reaction was filtered out, and the ethanol solvent in the filtrate was completely distilled off under reduced pressure. The crude product of methylamine bis(trifluoromethanesulfonyl)imide was obtained as white crystals at 60°C, with a yield of not less than 95%.

[0042] Table 1 Effect of different raw material stoichiometric ratios on the purity and yield of methylamine bis(trifluoromethanesulfonyl)imide

[0043]

[0044] Example 3

[0045] Purification of methylamine bis(trifluoromethanesulfonyl imide).

[0046] The crude methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) obtained above was dissolved in an appropriately treated anhydrous polar solvent, and then anhydrous dichloromethane was slowly added dropwise to the solution under stirring until a small amount of crystals precipitated. After being stored in a refrigerator at -20°C for 24 hours, pure white needle-shaped MATSFI crystals were obtained by filtration. After testing, the purity of the product after two recrystallization treatments can reach 99.9%.

[0047] like Figure 2 The melting point of the purified methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) in Example 3 of the present invention is 48°C.

[0048] like Figure 3 Shown is the purified MATSFI of Example 3 of the present invention. 1 H NMR (DMSO) spectrum; Figure 4 Shown is the purified MATSFI of Example 3 of the present invention. 19 F NMR (DMSO) spectrum; Figure 5 Shown is the purified MATSFI of Example 3 of the present invention. 13 C NMR (DMSO) spectrum.

[0049] 1 H NMR (DMSO) δ: 7.45 (3H, NH3), 2.33 (3H, CH3)

[0050] 19 F NMR (DMSO) δ: -78.65 (6F, 2×CF3)

[0051] 13 C NMR (DMSO) δ: 124.80~115.20 (2C, 2×CF3), 24.95 (1C, CH3)

[0052] like Figure 6 This is the differential scanning calorimetry (DSC) test curve of the purified MATSFI of Example 3 of the present invention.

[0053] T m =46.3℃

[0054] like Figure 7This is the thermogravimetric analyzer (TGA) test curve of the purified MATSFI of Example 3 of the present invention.

[0055] T d =320.8℃

[0056] The present invention also provides the use of the methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) in the preparation of solar cells.

[0057] Example 4

[0058] Application of methylamine bis(trifluoromethanesulfonyl)imide (MATSFI) in the preparation of solar cells.

[0059] 6 mg of methylamine bis(trifluoromethanesulfonyl)imide (MATSFI), 28 mg of 4-tert-butylpyridine (t-BP), and 90 mg of 2,2″,7,7″-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD) were dissolved in 1 mL of chlorobenzene to obtain a MATSFI-based charge transport layer material solution.

[0060] The MATSFI-based charge transport layer material solution obtained above was spin-coated on the photovoltaic layer to form a thin film at a rotation speed of 4000 rpm, an acceleration of 2000 rpm, and a spin time of 30 seconds.

[0061] like Figure 8 Shown are scanning electron microscope (SEM) photos of the top surface of the solar cell before and after coating with MATSFI as the charge transport layer material according to Example 4 of the present invention. The photos show that the original photovoltaic layer is completely covered after coating with the MATSFI-based charge transport layer.

[0062] like Figure 9 Shown are cross-sectional scanning electron microscope (SEM) images of a solar cell before and after coating with MATSFI as a charge transport layer material according to Example 4 of the present invention. The images show that the thickness of the MATSFI-based charge transport layer after coating is approximately 100 to 150 nm.

[0063] like Figure 10 The charge mobility curve of MATSFI as the charge transport layer material in Example 4 of the present invention is measured by the space charge limited current method (SCLC). The transfer rate of the charge transport layer based on MATSFI is calculated to be 1.58×10 -4 cm 2 v -1 s -1 .

[0064] like Figure 11The figure shows the work function of MATSFI of Example 4 of the present invention as a charge transport layer material measured by ultraviolet photoelectron spectroscopy (UPS), with a Fermi edge of 16.57 eV and a cutoff edge of 0.34 eV.

[0065] like Figure 12 The voltage-current (JV) curve of the solar cell with MATSFI as the charge transport layer material in Example 4 of the present invention is shown. The positive scan open circuit voltage is 1.137 V and the short circuit current is 25.85 mA / cm 2 , fill factor is 81.09%, conversion efficiency is 23.84%; reverse scan open circuit voltage is 1.158V, short circuit current is 25.84mA / cm 2 , the fill factor is 81.10%, and the conversion efficiency is 24.25%.

[0066] It should be noted that the above preferred embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit and essence of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. Application of a methylamine bis(trifluoromethanesulfonyl imide) compound in the preparation of solar cells. The structural formula of the methylamine bis(trifluoromethanesulfonyl imide) compound is shown below:

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