A method for synthesizing hole transport layer material Spiro-OMeTAD

Abstract

The invention discloses a synthesis method of a hole transport layer material Spiro-OMeTAD, comprising the following steps: reacting 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and 4,4'-dimethoxydiphenylamine under the catalysis of a nitrogen heterocyclic carbene palladium complex to obtain the hole transport layer material Spiro-OMeTAD; the structure of the nitrogen heterocyclic carbene palladium complex is shown in formula (I): formula (I); the invention adopts the nitrogen heterocyclic carbene palladium complex to catalyze the preparation of the hole transport layer material Spiro-OMeTAD, has the advantages of small catalyst dosage, high product purity and high catalytic efficiency, and overcomes the problems of high catalytic toxicity of phosphine ligands.

Description

Technical Field

[0001] The invention belongs to the technical field of organic optoelectronic polymer materials, and in particular relates to a method for synthesizing a hole transport layer material Spiro-OMeTAD. Background Art

[0002] Perovskite solar cells have become the focus of research as a new generation of solar cells with high performance and high application value.

[0003] The structure of perovskite solar cells includes a substrate layer, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal back electrode. Among them, the hole transport layer material plays an important role in extracting and transporting photogenerated holes, inhibiting carrier recombination, and protecting the perovskite layer in perovskite solar cells. Therefore, the development of efficient and stable hole transport materials is a research hotspot in the field of perovskite solar cells.

[0004] The commonly used hole transport layer material is mainly Spiro-OMeTAD, which is a type of efficient hole material in perovskite solar cells. Traditionally, palladium / phosphine ligands are often used to catalyze the preparation of Spiro-OMeTAD, but phosphine ligands are not only highly toxic, but also extremely sensitive to air and water vapor, making the conditions for catalytic reactions involving phosphine ligands extremely harsh. In order to solve the problems of phosphine ligands, researchers have discovered that nitrogen heterocyclic carbenes are excellent electron donors, which are called "phosphine-like ligands" in catalytic reactions. They are relatively stable to air and water vapor in the reaction and can be used as palladium-catalyzed ligands for the catalytic preparation of Spiro-OMeTAD. However, the existing nitrogen heterocyclic carbene palladium complexes are used in a high amount for the catalytic preparation of Spiro-OMeTAD, and the purity of the catalytic preparation of Spiro-OMeTAD is not high. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, a method for synthesizing Spiro-OMeTAD, a hole transport layer material, is provided. The present invention adopts nitrogen heterocyclic carbene palladium complex to catalyze the preparation of Spiro-OMeTAD, a hole transport layer material, which has the advantages of small catalyst dosage, high product purity and high catalytic efficiency, and overcomes the problems of high catalytic toxicity of phosphine ligands.

[0006] The object of the present invention is to provide a method for synthesizing a hole transport layer material Spiro-OMeTAD, comprising the following steps:

[0007] Under the catalysis of nitrogen heterocyclic carbene palladium complex, 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and 4,4'-dimethoxydiphenylamine react to obtain the hole transport layer material Spiro-OMeTAD;

[0008] The structure of the nitrogen heterocyclic carbene palladium complex is shown in formula (I):

[0009]

[0010] Formula (I)

[0011] Wherein, R1, R2 and R3 are independently selected from H or C1~C6 alkyl, and X is selected from Cl or Br.

[0012] In some embodiments of the present invention, R1, R2 and R3 are independently selected from H or C1~C3 alkyl.

[0013] In some embodiments of the present invention, R1 or R2 is independently selected from methyl, ethyl or isopropyl, R3 is selected from H or methyl, and R1 is the same as R2.

[0014] In some embodiments of the present invention, the molar ratio of the 4,4'-dimethoxydiphenylamine, 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and the nitrogen heterocyclic carbene palladium complex is 4.1-7.5:1:0.0015-0.0100.

[0015] In some embodiments of the present invention, the reaction further comprises an inorganic base.

[0016] In some embodiments of the present invention, the inorganic base is selected from potassium tert-butoxide.

[0017] In some embodiments of the present invention, the molar ratio of the inorganic base to 2,2',7,7'-tetrabromo-9,9'-spirobifluorene is 5.1-9.5:1.

[0018] In some embodiments of the present invention, the reaction temperature is 80-110° C. and the reaction time is 8-24 h.

[0019] In some embodiments of the present invention, the reaction further comprises a solvent, and the solvent is selected from toluene.

[0020] In some embodiments of the present invention, after the reaction is completed, a purification step is further included.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention utilizes nitrogen heterocyclic carbene palladium complexes to efficiently catalyze the preparation of Spiro-OMeTAD, which has the advantages of small catalyst dosage, high product purity and high catalytic efficiency, and overcomes the problems of high catalytic toxicity of phosphine ligands and sensitivity to water and air.

[0023] (2) The purification steps of the hole transport layer material Spiro-OMeTAD of the present invention are simple, and high-purity Spiro-OMeTAD can be obtained by only using recrystallization, thereby overcoming the shortcomings of the synthesis process, such as multiple product components, complex purification steps, large catalyst dosage, and environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the H NMR spectrum of Spiro-OMeTAD provided in Example 1. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] All raw materials of the present invention are conventionally commercially available.

[0027] The synthesis route of the hole transport layer material Spiro-OMeTAD of the present invention is as follows:

[0028]

[0029] Example 1

[0030] This embodiment provides a preparation of a nitrogen heterocyclic carbene palladium complex C1, which specifically includes the following steps:

[0031] S1. 2,4,6-trimethylaniline (4.4mmol), 4,7-di-tert-butylacenaphthenequinone (2mmol), and anhydrous zinc chloride (4.6mmol) were added to a 100 ml side-mouth bottle in sequence, and 50 ml of glacial acetic acid was added as solvent. The reaction was refluxed at 120°C under N2 protection for 5 hours. After the reaction was completed, the solution was cooled to room temperature. An orange-yellow solid was generated in the solution. The solution was filtered and the filter cake was rinsed with glacial acetic acid for several times to remove the unreacted raw materials. The solid obtained by filtration was dried and dissolved in dichloromethane. The solution was dezincified with 100 mL of potassium oxalate aqueous solution (4.6 g / L). After stirring for 5 hours, the white zinc salt was removed by filtration. The remaining organic layer was extracted with water for several times, and then spin-dried and recrystallized with (dichloromethane / n-hexane) to obtain orange-yellow crystals, i.e., diimine compound D1, with a yield of 64%;

[0032] S2. Weigh the diimine compound D1 (1.0 mmol) into a 25 ml stoppered bottle, add 3-4 ml of chloromethyl ether to dissolve it, expel the air in the bottle with N2 and seal it, react at 100 ° C for 24 hours, and after treatment, obtain compound E1 with a yield of 78%;

[0033] Weigh compound E1 (0.2 mmol), palladium chloride (0.22 mmol), potassium carbonate (2 mmol), and 3-chloropyridine (1.2 mmol) into a reaction bottle, add acetone to cover the solid, react at 60°C for 8 h, and after treatment, obtain a yellow solid, i.e., nitrogen heterocyclic carbene palladium complex C1, with a yield of 45%;

[0034] The NMR data of the nitrogen heterocyclic carbene palladium complex C1 are as follows:

[0035] 1 H NMR (600 MHz, CDCl3) δ 8.67 (d, J = 2.3 Hz, 1H), 8.59 (dd, J = 5.6,1.3 Hz, 1H), 7.69 (s, 2H), 7.58 (t, J = 8.3, 1.8 Hz, 1H), 7.15 (s, 4H), 7.12– 7.09 (m, 1H), 6.98 (d, J = 1.3 Hz, 2H), 2.45 (d, J = 13.5 Hz, 17H), 1.31 (s, 16H).

[0036] 13 C NMR (101 MHz, CDCl3) δ 155.18, 151.42, 150.65, 149.73, 139.41,139.03, 137.63, 136.17, 133.81, 132.09, 129.54, 129.00, 126.38, 125.43,124.43, 122.99, 118.94, 35.53, 31.46, 21.53, 19.29.

[0037] Example 2

[0038] This embodiment provides a preparation of a nitrogen heterocyclic carbene palladium complex C2, which specifically includes the following steps:

[0039] S1. 2,6-diethylaniline (4.4mmol), 4,7-di-tert-butylacenaphthenequinone (2mmol), and anhydrous zinc chloride (4.6mmol) were added to a 100 ml side-mouth bottle in sequence, and 50 ml of glacial acetic acid was added as solvent. The reaction was refluxed at 120°C under N2 protection for 5 hours. After the reaction was completed, the solution was cooled to room temperature. An orange-yellow solid was generated in the solution. The solution was filtered and the filter cake was rinsed with glacial acetic acid for several times to remove the unreacted raw materials. The solid obtained by filtration was dried and dissolved in dichloromethane. The zinc removal reaction was carried out with 100 mL of potassium oxalate aqueous solution (4.6 g / L). After stirring for 5 hours, the white zinc salt was filtered off. The remaining organic layer was extracted with water for several times, and then spin-dried and recrystallized with (dichloromethane / n-hexane) to obtain orange-yellow crystals, i.e., diimine compound D2, with a yield of 62%;

[0040] S2. Weigh the diimine compound D2 (1.0 mmol) into a 25 ml stoppered bottle, add 3-4 ml of chloromethyl ether to dissolve it, expel the air in the bottle with N2 and seal it, react at 100 ° C for 24 hours, and after treatment, obtain compound E2 with a yield of 52%;

[0041] Compound E2 (0.2 mmol), palladium chloride (0.22 mmol), potassium carbonate (2 mmol), and 3-chloropyridine (1.2 mmol) were weighed into a reaction bottle, acetone was added to cover the solid, and the mixture was reacted at 60°C for 8 h. After treatment, a yellow solid, i.e., nitrogen heterocyclic carbene palladium complex C2, was obtained with a yield of 56%;

[0042] The NMR data of the nitrogen heterocyclic carbene palladium complex C2 are as follows:

[0043] 1 H NMR (400 MHz, CDCl3) δ 8.58 (d, J = 2.3 Hz, 1H), 8.49 (dd, J = 5.5,1.1 Hz, 1H), 7.68 (d, J = 0.9 Hz, 2H), 7.62 – 7.54 (m, 3H), 7.43 (d, J = 7.7Hz, 4H), 7.08 (dd, J = 8.2, 5.5 Hz, 1H), 6.98 (d, J = 1.0 Hz, 2H), 2.98 (t, J= 15.3, 7.7 Hz, 4H), 2.80 (t, J = 15.4, 7.5 Hz, 4H), 1.28 (s, 18H), 1.11 (t,J = 7.5 Hz, 12H).

[0044] 13C NMR (101 MHz, CDCl3) δ 156.37, 151.35, 150.57, 149.66, 142.32,139.67, 137.59, 134.98, 132.07, 130.37, 129.02, 126.69, 126.44, 125.43,124.43, 122.93, 119.60, 35.53, 31.35, 25.11, 14.69.

[0045] Example 3

[0046] This embodiment provides a preparation of a nitrogen heterocyclic carbene palladium complex C3, which specifically includes the following steps:

[0047] S1. 2,6-diisopropylaniline (4.4mmol), 4,7-di-tert-butylacenaphthenequinone (2mmol), and anhydrous zinc chloride (4.6mmol) were added to a 100 ml side-mouth bottle in sequence, and 50 ml of glacial acetic acid was added as solvent. The reaction was refluxed at 120°C under N2 protection for 5 hours. After the reaction was completed, the solution was cooled to room temperature. An orange-yellow solid was generated in the solution. The solution was filtered and the filter cake was rinsed with glacial acetic acid for several times to remove the unreacted raw materials. The solid obtained by filtration was dried and dissolved in dichloromethane. The zinc removal reaction was carried out with 100 mL of potassium oxalate aqueous solution (4.6 g / L). After stirring for 5 hours, the white zinc salt was filtered off. The remaining organic layer was extracted with water for several times, and then recrystallized with (dichloromethane / n-hexane) to obtain orange-yellow crystals, i.e., diimine compound D3, with a yield of 68%;

[0048] S2. Weigh the diimine compound D3 (1.0 mmol) into a 25 ml stoppered bottle, add 3-4 ml of chloromethyl ether to dissolve it, expel the air in the bottle with N2 and seal it, react at 100 ° C for 24 hours, and after treatment, obtain compound E3 with a yield of 48%;

[0049] Compound E3 (0.2 mmol), palladium chloride (0.22 mmol), potassium carbonate (2 mmol), and 3-chloropyridine (1.2 mmol) were weighed into a reaction bottle, acetone was added to cover the solid, and the reaction was carried out at 60°C for 8 h. After treatment, a yellow solid, i.e., nitrogen heterocyclic carbene palladium complex C3, was obtained with a yield of 57%;

[0050] The NMR data of the nitrogen heterocyclic carbene palladium complex C3 are as follows:

[0051] 1H NMR (400 MHz, CDCl3) δ 8.70 (d, J = 2.3 Hz, 1H), 8.62 (dd, J = 5.5,1.1 Hz, 1H), 7.64 (d, J = 12.3 Hz, 4H), 7.57 (d, J = 8.3 Hz, 1H), 7.49 (d, J= 7.8 Hz, 4H), 7.10 (dd, J = 8.2, 5.6 Hz, 1H), 6.81 (s, 2H), 3.39 (t, J =13.4, 6.7 Hz, 4H), 1.46 (d, J = 6.6 Hz, 12H), 1.24 (s, 18H), 0.91 (d, J = 6.8Hz, 12H).

[0052] 13 C NMR (101 MHz, CDCl3) δ 157.96, 150.81, 149.74, 147.42, 140.81,137.55, 133.99, 132.00, 130.82, 128.92, 126.41, 125.68, 124.79, 124.44,122.66, 120.90, 35.45, 31.18, 29.01, 25.83, 24.39.

[0053] Example 4

[0054] This embodiment provides a method for synthesizing a hole transport layer material Spiro-OMeTAD, which specifically includes the following steps:

[0055] Under nitrogen protection, 2,2',7,7'-tetrabromo-9,9'-spirobifluorene (5.0mmol), 4,4'-dimethoxydiphenylamine (20.0mmol), potassium tert-butoxide (40.0mmol), nitrogen heterocyclic carbene palladium complex C1 (0.025mmol) and 50mL toluene were added to a 100mL side-mouth round-bottom flask, and the mixture was stirred at 90°C for 12 hours. After the reaction was completed, it was cooled to room temperature, and the organic layer was extracted three times with water / ethyl acetate. The organic layer was collected, the solvent was removed under vacuum, and then recrystallized with dichloromethane / petroleum ether. The precipitated solid was stirred and washed with petroleum ether for several times to obtain a light yellow final product, i.e., the hole transport layer material Spiro-OMeTAD, with a yield of 75.1% and a purity of 99.8%.

[0056] The H NMR spectrum data of the hole transport layer material Spiro-OMeTAD are as follows:

[0057] 1H NMR (400 MHz, DMSO-d6) δ 7.46 (d, J = 8.3 Hz, 4H), 6.89 – 6.77 (m,32H), 6.69 (dd, J = 8.2, 2.2 Hz, 4H), 6.18 (d, J = 2.2 Hz, 4H), 3.71 (s,24H).

[0058] Example 5

[0059] This embodiment provides a method for synthesizing a hole transport layer material Spiro-OMeTAD, which specifically includes the following steps:

[0060] The only difference from Example 4 is that the nitrogen heterocyclic carbene palladium complex C1 is replaced by the nitrogen heterocyclic carbene palladium complex C2, and the other steps are the same as Example 4, to obtain a light yellow final product, namely, the hole transport layer material Spiro-OMeTAD, with a yield of 78.3% and a purity of 99.8%.

[0061] Example 6

[0062] This embodiment provides a method for synthesizing a hole transport layer material Spiro-OMeTAD, which specifically includes the following steps:

[0063] The only difference from Example 4 is that the nitrogen heterocyclic carbene palladium complex C1 is replaced by the nitrogen heterocyclic carbene palladium complex C3, and the other steps are the same as Example 4, to obtain a light yellow final product, namely, the hole transport layer material Spiro-OMeTAD, with a yield of 69.8% and a purity of 99.8%.

[0064] Comparative Example 1

[0065] This embodiment provides a method for synthesizing a hole transport layer material Spiro-OMeTAD, which specifically includes the following steps:

[0066] The only difference from Example 4 is that the nitrogen heterocyclic carbene palladium complex C1 is replaced by tetrakis(triphenylphosphine)palladium, and the other steps are the same as Example 4, to obtain a light yellow final product, namely, the hole transport layer material Spiro-OMeTAD, with a yield of 42.0% and a purity of 99.0%.

[0067] Comparative Example 2

[0068] This embodiment provides a method for synthesizing a hole transport layer material Spiro-OMeTAD, which specifically includes the following steps:

[0069] The only difference from Example 4 is that the nitrogen heterocyclic carbene palladium complex C1 is replaced by [1,1-bis(diphenylphosphino)ferrocene]palladium dichloride, and the other steps are the same as Example 4, to obtain a light yellow final product, namely, the hole transport layer material Spiro-OMeTAD, with a yield of 49.2% and a purity of 98.5%.

[0070] By comparing Examples 4 to 6 with Comparative Examples 1 to 2, it can be seen that the present invention utilizes nitrogen heterocyclic carbene palladium complexes to efficiently catalyze the preparation of Spiro-OMeTAD, which has the advantages of small catalyst dosage, high product purity and high catalytic efficiency, and overcomes the problems of high catalytic toxicity of phosphine ligands and sensitivity to water and air.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the specification of this application, the technicians can still modify or replace the specific implementation mode of the present invention with equivalents, but these modifications or changes do not deviate from the scope of protection of the pending claims of the present application.

Claims

1. A method for synthesizing a hole transport layer material Spiro-OMeTAD, characterized in that: The steps include: Under the catalysis of nitrogen heterocyclic carbene palladium complex, 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and 4,4'-dimethoxydiphenylamine react to obtain the hole transport layer material Spiro-OMeTAD; The structure of the nitrogen heterocyclic carbene palladium complex is shown in formula (I): Wherein, R1 or R2 is independently selected from methyl, ethyl or isopropyl, R3 is selected from H or methyl, R1 is the same as R2, and X is selected from Cl or Br.

2. The method for synthesizing the hole transport layer material Spiro-OMeTAD according to claim 1, characterized in that: The molar ratio of the 4,4'-dimethoxydiphenylamine, 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and the nitrogen heterocyclic carbene palladium complex is 4.1-7.5:1:0.0015-0.0100.

3. The method for synthesizing the hole transport layer material Spiro-OMeTAD according to claim 2, characterized in that: The reaction also includes an inorganic base.

4. The method for synthesizing the hole transport layer material Spiro-OMeTAD according to claim 3, characterized in that: The inorganic base is selected from potassium tert-butoxide.

5. The method for synthesizing the hole transport layer material Spiro-OMeTAD according to claim 3, characterized in that: The molar ratio of the inorganic base to 2,2',7,7'-tetrabromo-9,9'-spirobifluorene is 5.1-9.5:

1.

6. The method for synthesizing the hole transport layer material Spiro-OMeTAD according to claim 1, characterized in that: The reaction temperature is 80-110° C. and the reaction time is 8-24 hours.

7. The method for synthesizing the hole transport layer material Spiro-OMeTAD according to claim 1, characterized in that: The reaction further comprises a solvent, and the solvent is selected from toluene.

8. The method for synthesizing the hole transport layer material Spiro-OMeTAD according to claim 1, characterized in that: After the reaction is completed, a purification step is also included.

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