A condensed ring small molecule containing an amino side chain and its preparation method and application

Abstract

The present invention discloses a condensed ring small molecule containing an amino side chain, and provides a class of alcohol-soluble sulfur-containing condensed ring small molecules containing an amine group or a quaternary ammonium salt in the side chain. The sulfur-containing condensed ring small molecule has a broad and flat conjugated skeleton structure, can form a good intermolecular stacking, and can effectively carry out carrier transport within and between molecules when applied to the cathode interface layer. The test results of positive organic solar cells show that such small molecules can be applied to the cathode interface layer through processes such as orthogonal solution spin coating, present good cathode modification performance, can significantly improve the photovoltaic performance parameters of the device, and have a bright application prospect.

Description

Technical Field

[0001] The present invention relates to the field of organic optoelectronic technology, and in particular to a condensed ring small molecule containing an amino side chain, a preparation method and an application thereof. Background Art

[0002] Organic solar cells have the advantages of being cheap, lightweight, and can be produced in large areas at high speed through roll-to-roll solution printing technology, and can be made into all-solid-state semi-transparent flexible components. They are of great value in solving the energy crisis and environmental pollution problems in the future. In recent years, their power conversion efficiency has exceeded 19%, and their commercial prospects are becoming increasingly bright. Among them, the organic cathode interface layer can enhance the electron transmission and collection of the cathode, reduce the carrier recombination loss of the cathode, and effectively protect the active layer from the corrosion of water, oxygen and cathode metal atoms, which is the key to ensuring the performance of the device. Therefore, the development of efficient organic cathode interface materials is a scientific problem that must be solved to promote the commercialization of organic solar cells. At present, although there are many varieties of organic cathode interface materials, many of them have obvious defects. For example, the shortcomings of polymer interface materials such as PFN and PFNBr include low purity, unclear structure, molecular weight dispersion, and low batch reproducibility, which significantly increases the difficulty of their application in large-scale organic photovoltaics. In this regard, many research institutions and scientific research institutes are committed to developing related high-performance materials. Summary of the invention

[0003] The present invention aims at the problems faced by current organic solar cells, and provides a class of alcohol-soluble sulfur hetero-condensed ring small molecules with amine groups or quaternary ammonium salts in the side chains. The sulfur hetero-condensed ring small molecules have a broad and smooth conjugated skeleton structure, can form good intermolecular stacking, and can effectively carry out carrier transmission within and between molecules when applied to the cathode interface layer. In addition, the amine groups or quaternary ammonium salts in the side chains have excellent cathode interface modification capabilities, can reduce the cathode work function, passivate interface charge trap states, dope receptors, etc., thereby significantly improving the cathode interface characteristics and improving device efficiency. At the same time, the amine groups or quaternary ammonium salts can also give the small molecules alcohol solvent dissolution and processing characteristics, thereby realizing the preparation of positive organic solar cells with intact active layer / cathode interface layer interfaces by low-cost orthogonal solution processes. The present invention can obtain the small molecules through a series of reactions such as Suzuki coupling and electrophilic substitution type molecular intramolecular ring closure. The test results of the positive organic solar cell show that such small molecules can be applied to the cathode interface layer through processes such as orthogonal solution spin coating, present good cathode modification performance, can significantly improve the photovoltaic performance parameters of the device, and have bright application prospects.

[0004] One object of the present invention is to provide a condensed ring small molecule containing an amino side chain, which is selected from one or more of the following chemical structures:

[0005]

[0006] Wherein, R is selected from a side chain containing an amino group, and the structure of the side chain containing an amino group includes an amino group or a quaternary ammonium salt;

[0007] The R1-R4 are selected from hydrogen atoms or alkyl chains.

[0008] Furthermore, the structures constituting the amino-containing side chains may include one or more of a phenoxy structure, an alkyl structure, and an alkoxy structure.

[0009] Furthermore, the alkyl chain has 1-10 carbon atoms.

[0010] Furthermore, the structure of the side chain containing an amino group is selected from one or more of the following structures:

[0011]

[0012] wherein m, n and o are independently selected from 0 to 2, p is selected from 1 to 9, and X is bromine or iodine.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned condensed ring small molecule containing an amino side chain, which comprises the following steps:

[0014] S1, carrying out a grafting reaction between a brominated substrate containing active hydrogen and a dibromoalkane in the presence of a phase transfer catalyst, a base and a solvent to obtain an intermediate product 1;

[0015] S2, under the protection of inert gas, reacting the intermediate product 1 with an amino group-containing reactant under alkaline conditions to obtain an intermediate product 2;

[0016] S3, under the protection of inert gas, subjecting the intermediate product 2 to a Suzuki reaction with 2-(methylsulfoxide)phenylboronic acid ester to obtain an intermediate product 3;

[0017] S4, dissolving the intermediate product 3 in trifluoroacetic acid, adding phosphorus pentoxide, and performing post-treatment after the reaction to obtain the target product 1;

[0018] S5, quaternizing the target product 1 to obtain the target product 2.

[0019] The above-mentioned alkali can be selected from aqueous solutions of common substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc., and its concentration is generally 40-60wt%

[0020] Furthermore, the brominated substrate is selected from a fused ring derivative structure containing fluorene or carbazole.

[0021] Indene, dibromocarbazole, etc., and the above optional structure must contain an active hydrogen structure, and the active hydrogen can be a hydrogen atom on a hydroxyl group or a hydrogen atom connected to the N atom of carbazole, so that subsequent bromination reaction can be carried out.

[0022] Furthermore, the carbon number of the dibromoalkane is selected from 1 to 20.

[0023] Another object of the present invention is to provide the use of the above-mentioned condensed ring small molecule containing an amino side chain in solar cells.

[0024] Among them, the condensed ring small molecules containing amino side chains are dissolved in an organic solvent (concentration is about 0.2-2 mg / ml) and then formed into a film on the device structure by spin coating, inkjet printing or printing to form a film with a thickness of 4-10 nm.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The alcohol-soluble sulfur-containing condensed ring small molecule with an amine group or a quaternary ammonium salt in the side chain prepared by the present invention has a broad and flat conjugated skeleton structure, which is more conducive to forming a good intermolecular stacking compared with the polyfluorene material. When applied to the cathode interface layer of an organic solar cell, it can carry out efficient carrier transport within and between molecules, which helps to improve the charge transfer efficiency of the device;

[0027] 2. The alcohol-soluble sulfur-containing condensed ring small molecule with an amine group or a quaternary ammonium salt in the side chain prepared by the present invention has a bluer UV-visible absorption spectrum than polyfluorene and perylene imide interface materials, which can reduce the absorption of light by the cathode interface layer, thereby increasing the device photocurrent and contributing to the realization of efficient organic solar cells;

[0028] 3. Compared with polymer-based interface materials, the alcohol-soluble sulfur-containing condensed ring small molecules with amine groups or quaternary ammonium salts in the side chains prepared by the present invention have high purity, clear chemical structure, and unique molecular weight, and can achieve good batch reproducibility, which is helpful for the large-scale preparation of organic solar cells;

[0029] 4. The alcohol-soluble sulfur-containing fused ring small molecules with amine or quaternary ammonium salt side chains prepared by the present invention have good alcohol solvent solubility and processing characteristics. Positive organic solar cells with intact active layer / cathode interface layer can be prepared by low-cost orthogonal solution process, which is helpful to promote the industrialization of organic solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 For M1 1 H NMR spectrum (solvent: CDCl3);

[0031] Figure 2 For M2 1 H NMR spectrum (solvent: DMSO-d6);

[0032] Figure 3 Thermogravimetric analysis curves of M1 and M2;

[0033] Figure 4 is the UV-visible absorption spectra of M1 and M2 in the film;

[0034] Figure 5 The current density-voltage characteristic curve of the positive organic solar cell with M1 and M2 as the cathode interface layer (device structure: ITO (180nm) / PEDOT:PSS (40nm) / PM6:Y6 (150nm) / cathode interface layer (6nm) / Ag (150nm)). DETAILED DESCRIPTION

[0035] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0036] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0037] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all instances by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0038] Example 1

[0039] A preparation method of a condensed ring small molecule M1 containing an amino side chain comprises the following steps:

[0040]

[0041] S1. Preparation of 4-(3-bromopropoxy)phenyl substituted dibromofluorene (2)

[0042] Compound 1 (10.00 g, 19.68 mmol), tetrabutylammonium bromide (63.4 mg, 0.1968 mmol), Br(CH2)3Br (23.84 g, 118.1 mmol) were mixed in dimethyl sulfoxide (100 mL), and sodium hydroxide aqueous solution (50 wt%, 8.00 mL) was added to the above system and stirred at 80 ° C for 8 h. After cooling, distilled water was added to dilute, and the organic phase was extracted with dichloromethane.

[0043] The product was washed with distilled water and saturated sodium chloride solution in turn, dried over anhydrous magnesium sulfate, the solvent was evaporated, and the product was purified by silica gel column chromatography using petroleum ether as eluent to obtain a white solid 2 with a yield of 74%.

[0044] S2. Preparation of 4-(3-dimethylaminopropoxy)phenyl substituted dibromofluorene (3)

[0045] Compound 2 (7.500 g, 9.997 mmol) was dissolved in N,N-dimethylformamide (60 mL), and anhydrous potassium carbonate (8.290 g, 59.98 mmol) and a tetrahydrofuran solution of dimethylamine (2M, 15.00 mL) were added under nitrogen protection, and stirred at 25°C for 8 h. Distilled water was added for dilution, and the mixture was extracted with dichloromethane. The organic phase was washed with distilled water and a saturated sodium chloride aqueous solution in turn, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the product was purified by silica gel column chromatography with dichloromethane / methanol (30 / 1, v / v) as the eluent to obtain a white solid 3 with a yield of 69%.

[0046] S3. Preparation of Suzuki coupling product (4) of 4-(3-dimethylaminopropyloxy)phenyl substituted fluorene and methylsulfoxide benzene

[0047] Compound 3 (5.000 g, 7.369 mmol) was dissolved in 1,4-dioxane (50 mL), and 2-(methylsulfoxy)phenyl borate (4.708 g, 17.69 mmol), tetrakis(triphenylphosphine)palladium (681.5 mg, 0.5895 mmol) and potassium carbonate aqueous solution (2M, 15.00 mL) were added under nitrogen protection, and stirred at 80°C for 8 h. After cooling, distilled water was added to dilute, and the mixture was extracted with dichloromethane. The organic phase was washed with distilled water and saturated sodium chloride aqueous solution in turn, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the product was purified by silica gel column chromatography with dichloromethane / methanol (30 / 1, v / v) as the eluent to obtain white solid 4 with a yield of 62%.

[0048] S4. Preparation of phenyl-substituted bis(benzothiophene)fluorene (M1) containing amine groups on the side chain

[0049] Under ice bath cooling, compound 4 (1.000 g, 1.255 mmol) was dissolved in trifluoroacetic acid (30 mL), phosphorus pentoxide (1.068 g, 7.527 mmol) was added, and the mixture was stirred at 30 °C for 16 h. The reaction solution was poured into ice water, filtered after stirring, and the filter residue was washed with water and dried. All the filter residues were dissolved in pyridine (30 mL) and stirred at 120 °C for 10 h. After cooling, distilled water was added to dilute, extracted with dichloromethane, and the organic phase was washed with distilled water and saturated sodium chloride aqueous solution in turn, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the product was purified by silica gel column chromatography with dichloromethane / methanol (30 / 1, v / v) as eluent to obtain white solid M1 with a yield of 55%. M1 1 HNMR spectrum Figure 1 shown.

[0050] Example 2

[0051] A preparation method of a condensed ring small molecule M2 containing an amino side chain comprises the following steps:

[0052]

[0053] Compound M1 (0.5000 g, 0.6821 mmol) was dissolved in tetrahydrofuran (5 mL) and iodine was added under nitrogen protection.

[0054] Ethane (0.55 mL, 6.821 mmol) was stirred at 25 °C for 16 h, during which an appropriate amount of methanol was added to dissolve the precipitate. The reaction solution was dried, methanol was added, stirred, and filtered. The filtrate was concentrated, ethyl acetate was added dropwise, stirred, and filtered to obtain a white solid M2 with a yield of 42%. 1 H NMR spectrum Figure 2 shown.

[0055] Figure 3 Thermogravimetric analysis curves of M1 and M2;

[0056] Figure 4 UV-visible absorption spectra of M1 and M2 in the film.

[0057] Example 3

[0058] A preparation method of a condensed ring small molecule M3 containing an amino side chain comprises the following steps:

[0059]

[0060] S1. Preparation of 6-bromohexyl substituted bisbromocarbazole (6)

[0061] Compound 5 (6.500 g, 20.00 mmol), tetrabutylammonium bromide (64.48 mg, 0.2000 mmol), Br(CH2)6Br (7.320 g, 30.00 mmol) were mixed in dimethyl sulfoxide (100 mL), and potassium hydroxide aqueous solution (50 wt%, 2.00 mL) was added to the above system and stirred at 100 °C for 16 h. After cooling, distilled water was added to dilute, and the organic phase was extracted with dichloromethane.

[0062] The phase was washed with distilled water and saturated sodium chloride aqueous solution in turn, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the product was purified by silica gel column chromatography using petroleum ether as eluent to obtain a white solid 6 with a yield of 85%.

[0063] S2. Preparation of 6-diethylaminohexyl-substituted bisbromocarbazole (7)

[0064] Compound 6 (5.000 g, 10.24 mmol) was dissolved in N,N-dimethylformamide (50 mL), and anhydrous potassium carbonate (2.124 g, 15.37 mmol) and diethylamine (0.8989 g, 12.29 mmol) were added under nitrogen protection, and stirred at 55°C for 6 h. After cooling, distilled water was added to dilute, and the mixture was extracted with dichloromethane. The organic phase was washed with distilled water and saturated sodium chloride aqueous solution in turn, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the product was purified by silica gel column chromatography with dichloromethane / methanol (30 / 1, v / v) as the eluent to obtain white solid 7 with a yield of 83%.

[0065] S3. Preparation of Suzuki coupling product (8) of 6-diethylaminohexyl substituted carbazole and methylsulfoxide benzene

[0066] Compound 7 (4.000 g, 8.328 mmol) was dissolved in tetrahydrofuran (35 mL), and 2-(methylsulfoxy)phenyl borate (5.321 g, 19.99 mmol), tetrakis(triphenylphosphine)palladium (481.4 mg, 0.4164 mmol) and potassium carbonate aqueous solution (2M, 12.50 mL) were added under nitrogen protection, and stirred at 65°C for 20 h. After cooling, distilled water was added to dilute, and extracted with dichloromethane. The organic phase was washed with distilled water and saturated sodium chloride aqueous solution in turn, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the product was purified by silica gel column chromatography with dichloromethane / methanol (30 / 1, v / v) as the eluent to obtain white solid 8 with a yield of 60%.

[0067] S4. Preparation of bis(benzothiophene)carbazole (M3) containing amine groups on the side chain

[0068] Under ice bath cooling, compound 8 (2.000 g, 3.339 mmol) was dissolved in trifluoroacetic acid (40 mL), phosphorus pentoxide (1.232 g, 8.683 mmol) was added, and the mixture was stirred at 20 °C for 13 h. The reaction solution was poured into ice water, stirred and filtered, and the residue was washed with water and dried. All the residues were dissolved in pyridine (40 mL) and stirred at 110 °C for 24 h. After cooling, distilled water was added to dilute, extracted with dichloromethane, and the organic phase was washed with distilled water and saturated sodium chloride aqueous solution in turn, and dried over anhydrous magnesium sulfate. The solvent was evaporated, and the product was purified by silica gel column chromatography with dichloromethane / methanol (30 / 1, v / v) as the eluent to obtain white solid M3 with a yield of 59%.

[0069] Example 4

[0070] A preparation method of a condensed ring small molecule M4 containing an amino side chain comprises the following steps:

[0071]

[0072] Compound M3 (0.5000 g, 0.9349 mmol) was dissolved in chloroform (8 mL), bromoethane (0.10 mL, 1.402 mmol) was added under nitrogen protection, and stirred at 60°C for 10 h. After cooling, the mixture was filtered, and the residue was dissolved in methanol. After filtering, the filtrate was concentrated, ethyl acetate was added dropwise, and the mixture was stirred and filtered to obtain a white solid M4 with a yield of 76%.

[0073] Test Case

[0074] Preparation of positive organic solar cells with alcohol-soluble small molecules M1-M2 as cathode interface layer

[0075] On the pre-prepared indium tin oxide (ITO) glass (thickness about 180nm), it was ultrasonically cleaned with detergent, deionized water, acetone and isopropanol in sequence, and treated with UV-ozone for 15min. A polyethoxythiophene (PEDOT:PSS) film doped with polystyrene sulfonic acid was spin-coated on the ITO. The PEDOT:PSS film was dried in an oven at 150°C in an air atmosphere for 15min, and its thickness was about 40nm. Subsequently, a chloroform solution (containing 0.5vt% 1-chloronaphthalene) (donor:acceptor=1:1.2, w / w) of a mixture of donor PM6 and acceptor Y6 was spin-coated on the surface of the PEDOT:PSS film, with a total solution concentration of 16mg / mL and an active layer thickness of about 150nm. Then, a 0.5 mg / mL concentration solution of alcohol-soluble sulfur-fused ring small molecule M1 (soluble in methanol containing 1 vt% acetic acid) or M2 (soluble in methanol) or PFN (the number average molecular weight of the polymer is 1132, and the PDI is 1.4; dissolved in methanol containing 1 vt% acetic acid, as a comparative example) with a side chain containing an amine group or a quaternary ammonium salt is spin-coated on the active layer to obtain a cathode interface layer with a thickness of about 6 nm. Finally, a metal Ag layer (about 150 nm) is vacuum evaporated on the cathode interface layer. The organic solar cells made of M1, M2, and PFN as the cathode interface layer have current density-voltage characteristic curves as shown below: Figure 5 The corresponding photovoltaic performance indicators are shown in Table 1:

[0076] Table 1 Solar cell performance data of Examples 1-2

[0077]

[0078] For the reference device without any cathode interface layer, the open circuit voltage, fill factor and short circuit current density are 0.627 V, 56.13% and 24.98 mA / cm, respectively. 2 , the corresponding power conversion efficiency is 8.79%. When PFN is used as the cathode interface layer, its open circuit voltage, fill factor and short circuit current density are 0.738V, 59.78% and 24.81mA / cm 2 , and the corresponding power conversion efficiency is 10.95%. When M1 is used as the cathode interface layer, the above parameters are increased to 0.773V, 62.56% and 25.78mA / cm 2 , the power conversion efficiency increased to 12.47%. When M2 is the cathode interface layer, the above parameters are 0.760V, 62.82% and 25.57mA / cm 2 , the power conversion efficiency is 12.21%. It can be seen that both M1 and M2 can significantly and synchronously improve the three performance parameters of photovoltaic devices, and the final efficiency improvement is 13.88% and 11.51% respectively, so this type of small molecule has a high application potential in the field of organic solar cells.

[0079] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the present invention is determined by the appended claims.

[0080] Rather than being limited to the above description, all changes coming within the meaning and range of equivalency of the claims are therefore intended to be embraced within the invention.

[0081] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A condensed ring small molecule containing an amino side chain, characterized in that: The chemical structure of the condensed ring small molecule containing an amino side chain is as follows: Wherein, R is selected from a side chain containing an amino group, and the structure of the side chain containing an amino group is selected from one or more of the following structures: wherein m, n and o are independently selected from 0 to 2, p is selected from 1 to 9, and X is bromine or iodine; The R1-R4 are selected from hydrogen atoms or alkyl chains.

2. The condensed ring small molecule containing an amino side chain according to claim 1, characterized in that: The alkyl chain has 1 to 10 carbon atoms.

3. The method for preparing a condensed ring small molecule containing an amino side chain according to any one of claims 1 to 2, characterized in that: The preparation method of the condensed ring small molecule containing an amino side chain comprises the following steps: S1, carrying out a grafting reaction between a brominated substrate containing active hydrogen and a dibromoalkane in the presence of a phase transfer catalyst, a base and a solvent to obtain an intermediate product 1; S2, under the protection of inert gas, reacting the intermediate product 1 with an amino group-containing reactant under alkaline conditions to obtain an intermediate product 2; S3, under the protection of inert gas, subjecting the intermediate product 2 to a Suzuki reaction with 2-(methylsulfoxide)phenylboronic acid ester to obtain an intermediate product 3; S4, dissolving the intermediate product 3 in trifluoroacetic acid, adding phosphorus pentoxide, and performing post-treatment after the reaction to obtain the target product 1; S5, quaternizing the target product 1 to obtain the target product 2, i.e. the condensed ring small molecule containing an amino side chain according to claim 1; The brominated substrate is selected from fluorene-containing fused ring derivative structures.

4. Use of the condensed ring small molecule containing an amino side chain as claimed in any one of claims 1 to 2 in solar cells.

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