An organic conjugated small molecule material with a cyanoindenone end group and its application

Abstract

The present invention provides an organic conjugated small molecule material with a cyanoindenone end group and its application, belonging to the technical field of organic solar cells. The organic conjugated small molecule material provided by the present invention has a structural formula shown in Formula Ι. The end group of the organic conjugated small molecule material provided by the present invention has a larger conjugated area and aggregation characteristics, which is beneficial to the self-assembly and stacking between molecules, thereby improving the photovoltaic performance of this type of small molecule material; moreover, this type of small molecule material has appropriate energy levels and is suitable as an electron acceptor material for use in organic solar cell devices; when this type of material is used as the acceptor material of an organic solar cell, it has a high energy conversion efficiency, which is of great significance for the development of the organic solar cell field.

Description

Technical Field

[0001] The present invention relates to the technical field of organic solar cells, and particularly relates to an organic conjugated small molecule material with a cyanoindenone end group and its application. Background Art

[0002] Organic solar cells have attracted great research enthusiasm in the academic and industrial fields due to their solution processability, good flexibility, high efficiency, light weight and other characteristics, and are one of the research hotspots in the new energy field. Since 1995, bulk heterojunction organic solar cells have attracted extensive attention. In the early stage, fullerene derivatives were the main electron acceptors in organic solar cells and played a crucial role in organic solar cell devices. However, due to the disadvantages of weak absorption, difficult chemical synthesis, strong aggregation and unstable morphology of fullerene derivatives, researchers chose to explore new molecular structures to replace fullerenes. Compared with fullerene acceptors, non-fullerene electron acceptors have the following advantages: non-fullerene acceptors usually exhibit better solubility, a wider light absorption range and adjustable energy levels. These advantages enable researchers to select more excellent donor materials to combine with them to achieve complementary absorption of visible light and near-infrared and energy level matching; non-fullerene acceptors can separate excitons to generate photo-generated charges at negligible or very low driving energies, and have lower voltage losses compared to fullerene acceptor-based photovoltaic devices, so they have received more and more attention. Organic small molecule acceptor materials have been studied more and more deeply due to their definite molecular structure and molecular weight, high purity and no batch differences, etc., which has greatly improved the efficiency of the devices.

[0003] It is not only very necessary but also very feasible to develop high-performance non-fullerene acceptor materials. Through chemical methods, the energy levels and absorption of organic compounds can be effectively improved, better matched with the absorption and energy levels of donor materials, and reasonable regulation of molecular interactions and energy level matching can make organic solar cells more efficient. Therefore, it is necessary to synthesize more types of conjugated small molecule acceptor materials to further improve the device efficiency. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an organic conjugated small molecule material with a cyanoindenone end group and its application. The end group of the organic conjugated small molecule material provided by the present invention has a larger conjugated area and aggregation characteristics, which is beneficial to intermolecular self-assembly and stacking, and thus improves the photovoltaic performance of this type of small molecule material.

[0005] In order to achieve the above purpose, the present invention provides the following technical solution: an organic conjugated small molecule material with a cyanoindenone end group having the structural formula shown in Formula Ι:

[0006]

[0007] Among them, Core is a fused-ring conjugated unit, and Ar is an aromatic heterocyclic unit.

[0008] Preferably, the Ar is selected from one of the following chemical structural formulas:

[0009]

[0010] Among them, R is hydrogen or an alkyl group having 1 to 30 carbon atoms, and one or more carbon atoms in the alkyl group can be substituted by a halogen atom, an oxygen atom, an alkenyl group, an alkynyl group, an aryl group, a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, an ester group, a cyano group or a nitro group.

[0011] The present invention also provides a preparation method of the organic conjugated small molecule material described in the above technical solution, including the following steps:

[0012] Step 1: The intermediate compound (1) containing an aldehyde functional group and bromocyanoindanone (2) undergo a Knoevenagel condensation reaction under the catalysis of a base to obtain compound (3); the base is preferably pyridine; the reaction temperature is 80 °C, and the reaction time is 12 h;

[0013] Step 2: Mix the tributyltin aromatic ring compound (4) and compound (3), and undergo a stille coupling reaction under the action of a palladium catalyst to obtain compound (5), that is, the target organic conjugated small molecule material; the reaction temperature is 80 °C, and the reaction time is 2 h.

[0014] The synthesis route is as follows:

[0015]

[0016] The present invention also provides an organic solar cell, and the photovoltaic material of the solar cell contains the organic conjugated small molecule material described above.

[0017] Preferably, the organic conjugated small molecule material is used as an active layer acceptor material for light capture in a solar cell.

[0018] The present invention characterized the structure of the organic conjugated small molecule material by nuclear magnetic resonance (NMR), mass spectrometry (MS), etc., characterized the electrochemical properties of the organic conjugated small molecule material by cyclic voltammetry, tested the spectral properties of the polymer material by an ultraviolet-visible spectrometer, and characterized their optoelectronic properties by fabricating them into organic photovoltaic devices.

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

[0020] 1. The end groups of the organic conjugated small molecule materials provided by the present invention have a larger conjugated area and aggregation characteristics, which are beneficial to the self-assembly and stacking between molecules, and thus improve the photovoltaic performance of such small molecule materials.

[0021] 2. The small molecule materials provided by the present invention have appropriate energy levels and are suitable as electron acceptor materials for use in organic solar cell devices.

[0022] 3. When the small molecule materials provided by the present invention are used as acceptor materials for organic solar cells, they have a high energy conversion efficiency, which is of great significance for the development of the field of organic solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the short-circuit current-voltage graph of the organic small molecule material A1 obtained in Example 1;

[0024] Figure 2 is the short-circuit current-voltage graph of the organic small molecule material A2 obtained in Example 2;

[0025] Figure 3 is the short-circuit current-voltage graph of the organic small molecule material A3 obtained in Example 3;

[0026] Figure 4 is the short-circuit current-voltage graph of the organic small molecule material A4 obtained in Example 4;

[0027] Figure 5 is the thin film absorption spectrum graph of the small molecule material A1 obtained in Example 1;

[0028] Figure 6 is the thin film absorption spectrum graph of the small molecule material A2 obtained in Example 2;

[0029] Figure 7 is the thin film absorption spectrum graph of the small molecule material A3 obtained in Example 3;

[0030] Figure 8 is the thin film absorption spectrum graph of the small molecule material A4 obtained in Example 4;

[0031] Figure 9 is the redox potential curve graph of the small molecule material A1 obtained in Example 1;

[0032] Figure 10 is the redox potential curve graph of the small molecule material A2 obtained in Example 2;

[0033] Figure 11 is the redox potential curve graph of the small molecule material A3 obtained in Example 3;

[0034] Figure 12Redox potential curve of the small molecule material A4 obtained in Example 4. Detailed implementation mode

[0035] The practice of the present invention can adopt the conventional techniques of polymer chemistry within the art. In the following examples, efforts are made to ensure the accuracy of the numbers used (including quantities, temperatures, reaction times, etc.), but some experimental errors and deviations should be considered. The temperatures used in the following examples are expressed in °C, and the pressures are atmospheric pressure or close to atmospheric pressure. All solvents are purchased at the analytical grade or chromatographic grade, and all reactions are carried out under an inert argon atmosphere. Unless otherwise indicated, all reagents are commercially available.

[0036] Example 1 Synthesis of the organic conjugated small molecule acceptor material A1

[0037]

[0038]

[0039] As shown in the above reaction formula:

[0040] 1) Add 508 mg of compound 1, 298.8 mg of 5-bromocyanoindanone (compound 2), and 30 mL of chloroform to a 100 mL dry two-necked flask in sequence. After stirring evenly at room temperature, introduce argon. After 20 minutes of aeration, add 1 mL of pyridine dropwise to the reaction solution, heat the reaction to 80 °C, and react for 12 hours. Post-treatment of the reaction: Restore the reaction to room temperature, directly separate and purify by column chromatography, the eluent is dichloromethane and petroleum ether, and the obtained compound is recrystallized in methanol to obtain the target compound 3.

[0041] 2) Prepare a 50 mL dry two-necked flask, introduce argon, and add 103.1 mg of compound 3, 2.0 mg of tris(dibenzylideneacetone)dipalladium, 3.6 mg of tris(o-tolyl)phosphine, and 63.5 mg of 2-tributylstannylthiazole (compound 4) to the reaction flask in sequence. Then add 2 mL of chlorobenzene dropwise to the reaction flask. After stirring evenly at room temperature, introduce argon. After 20 minutes of aeration, heat the reaction to 80 °C and react for 2 hours. Post-treatment of the reaction: Restore the reaction to room temperature, directly separate and purify by column chromatography, the eluent is dichloromethane and petroleum ether, and the obtained compound is recrystallized in methanol to obtain the target small molecule acceptor material A1.

[0042] Figure 5 Thin film absorption spectrum of the small molecule material A1 obtained in Example 1. It can be found that the small molecule material disclosed in the present invention has a wide and strong absorption, and this type of material has good sunlight capture ability.

[0043] Figure 9Redox potential curve diagram of small molecule material A1 obtained in Example 1. It can be calculated that the HOMO / LUMO energy levels of A1 are -5.71 / -3.90 eV respectively. It can be seen that the small molecule materials disclosed in the present invention have relatively deep LUMO energy levels and are suitable as electron acceptor materials for use in organic solar cell devices.

[0044] Synthesis of organic conjugated small molecule acceptor material A1 in Example 2

[0045]

[0046] As shown in the above reaction formula:

[0047] 1) Add 593.9 mg of compound 1, 273.8 mg of bromocyanoindenone (mixture 6), and 30 mL of chloroform to a 100 mL dry two-necked flask in sequence. After stirring evenly at room temperature, introduce argon. After 20 minutes of aeration, add 1 mL of pyridine dropwise to the reaction solution, heat the reaction to 80 °C, and react for 12 hours. Post-treatment of the reaction: Restore the reaction to room temperature, directly separate and purify by column chromatography, the eluent is dichloromethane and petroleum ether, and the obtained compound is recrystallized in methanol to obtain the target mixture 7.

[0048] 2) Prepare a 50 mL dry two-necked flask, introduce argon, and add 99.5 mg of mixture 7, 2.0 mg of tris(dibenzylideneacetone)palladium(II), 3.6 mg of tris(o-tolyl)phosphine, and 83.0 mg of 2-tributylstannylthiazole (compound 4) to the reaction flask in sequence. Then add 2 mL of chlorobenzene dropwise to the reaction flask. After stirring evenly at room temperature, introduce argon. After 20 minutes of aeration, heat the reaction to 80 °C and react for 2 hours. Post-treatment of the reaction: Restore the reaction to room temperature, directly separate and purify by column chromatography, the eluent is dichloromethane and petroleum ether, and the obtained compound is recrystallized in methanol to obtain the target small molecule acceptor material A2.

[0049] Figure 6 Film absorption spectrum diagram of small molecule material A2 obtained in Example 2. It can be found that the small molecule materials disclosed in the present invention have broad and strong absorption, and such materials have good sunlight capture ability.

[0050] Figure 10 Redox potential curve diagram of small molecule material A2 obtained in Example 2. It can be calculated that the HOMO / LUMO energy levels of A2 are -5.78 / -3.84 eV respectively. It can be seen that the small molecule materials disclosed in the present invention have relatively deep LUMO energy levels and are suitable as electron acceptor materials for use in organic solar cell devices.

[0051] Synthesis of organic conjugated small molecule acceptor material A3 in Example 3

[0052]

[0053] As shown in the above reaction formula:

[0054] 1) 8510.3 mg of compound 8, 250.7 mg of 5-bromocyanoindanone (compound 2) and 30 mL of chloroform were successively added to a 100 mL dry two-necked flask. After stirring evenly at room temperature, argon was introduced. After 20 minutes of aeration, 1 mL of pyridine was added dropwise to the reaction solution, and the reaction was heated to 80 °C for 12 hours. Post-treatment of the reaction: The reaction was restored to room temperature, and separation and purification were directly carried out by column chromatography. The eluent was dichloromethane and petroleum ether. The obtained compound was recrystallized in methanol to obtain the target compound 9.

[0055] 2) Prepare a 50 mL dry two-necked flask, introduce argon, and successively add 101.3 mg of compound 9, 2.0 mg of tris(dibenzylideneacetone)dipalladium, 3.6 mg of tris(o-tolyl)phosphine and 81.4 mg of 2-tributylstannylthiazole (compound 4) to the reaction flask. Then, 2 mL of chlorobenzene was added dropwise to the reaction flask. After stirring evenly at room temperature, argon was introduced. After 20 minutes of aeration, the reaction was heated to 80 °C for 2 hours. Post-treatment of the reaction: The reaction was restored to room temperature, and separation and purification were directly carried out by column chromatography. The eluent was dichloromethane and petroleum ether. The obtained compound was recrystallized in methanol to obtain the target small molecule acceptor material A3.

[0056] Figure 7 It is the thin film absorption spectrogram of the small molecule material A3 obtained in Example 3. It can be found that the small molecule material disclosed in the present invention has broad and strong absorption, and this kind of material has good sunlight capture ability.

[0057] Figure 11 It is the redox potential curve diagram of the small molecule material A3 obtained in Example 3. It can be calculated that the HOMO / LUMO energy levels of A3 are -5.85 / -3.89 eV respectively. It can be seen that the small molecule material disclosed in the present invention has a relatively deep LUMO energy level and is suitable as an electron acceptor material for use in organic solar cell devices.

[0058] Example 4 Synthesis of Organic Conjugated Small Molecule Acceptor Material A4

[0059]

[0060] As shown in the above reaction formula:

[0061] 1) 8507.4 mg of compound 8, 251.4 mg of bromocyaninoindanone (mixture 6) and 30 mL of chloroform were successively added to a 100 mL dry two-necked flask. After stirring evenly at room temperature, argon was introduced. After 20 minutes of aeration, 1 mL of pyridine was added dropwise to the reaction solution, and the reaction was heated to 80 °C and reacted for 12 hours. Post-treatment of the reaction: The reaction was restored to room temperature, and separation and purification were directly carried out by column chromatography. The eluent was dichloromethane and petroleum ether. The obtained compound was recrystallized in methanol to obtain the target mixture 10.

[0062] 2) A 50 mL dry two-necked flask was prepared, and argon was introduced. 99.7 mg of mixture 10, 2.0 mg of tris(dibenzylideneacetone)dipalladium, 3.6 mg of tris(o-tolyl)phosphine and 80.1 mg of 2-tributylstannylthiazole (compound 4) were successively added to the reaction flask. Then 2 mL of chlorobenzene was added dropwise to the reaction flask. After stirring evenly at room temperature, argon was introduced. After 20 minutes of aeration, the reaction was heated to 80 °C and reacted for 2 hours. Post-treatment of the reaction: The reaction was restored to room temperature, and separation and purification were directly carried out by column chromatography. The eluent was dichloromethane and petroleum ether. The obtained compound was recrystallized in methanol to obtain the target small molecule acceptor material A4.

[0063] Figure 8 It is the thin film absorption spectrum diagram of the small molecule material A4 obtained in Example 4. It can be found that the small molecule material disclosed in the present invention has broad and strong absorption, and this kind of material has good sunlight capture ability.

[0064] Figure 12 It is the redox potential curve diagram of the small molecule material A4 obtained in Example 4. It can be calculated that the HOMO / LUMO energy levels of A4 are -5.86 / -3.88 eV respectively. It can be seen that the small molecule material disclosed in the present invention has a relatively deep LUMO energy level and is suitable as an electron acceptor material for application in organic solar cell devices.

[0065] Example 5 Synthesis of Organic Conjugated Small Molecule Acceptor Material A5

[0066]

[0067] As shown in the above reaction formula:

[0068] 1) 11507.5 mg of compound 11, 323.1 mg of bromocyanoindanone (mixture 6) and 30 mL of chloroform were successively added to a 100 mL dry two-necked flask. After stirring evenly at room temperature, argon was introduced. After 20 minutes of aeration, 1 mL of pyridine was added dropwise to the reaction solution, and the reaction was heated to 80 °C for 12 hours. Post-treatment of the reaction: The reaction was restored to room temperature, and column chromatography was directly used for separation and purification. The eluent was dichloromethane and petroleum ether. The obtained compound was recrystallized in methanol to obtain the target mixture 12.

[0069] 2) A 50 mL dry two-necked flask was prepared, and argon was introduced. 100.5 mg of mixture 12, 2.0 mg of tris(dibenzylideneacetone)dipalladium, 3.6 mg of tris(o-tolyl)phosphine and 75.9 mg of 2-tributylstannylthiazole (compound 4) were successively added to the reaction flask. Then, 2 mL of chlorobenzene was added dropwise to the reaction flask. After stirring evenly at room temperature, argon was introduced. After 20 minutes of aeration, the reaction was heated to 80 °C for 2 hours. Post-treatment of the reaction: The reaction was restored to room temperature, and column chromatography was directly used for separation and purification. The eluent was dichloromethane and petroleum ether. The obtained compound was recrystallized in methanol to obtain the target small molecule acceptor material A5.

[0070] Example 6 Synthesis of Organic Conjugated Small Molecule Acceptor Material A6

[0071]

[0072] As shown in the above reaction formula:

[0073] A 50 mL dry two-necked flask was prepared, and argon was introduced. 101.1 mg of mixture 12 obtained in Example 5, 2.0 mg of tris(dibenzylideneacetone)dipalladium, 3.6 mg of tris(o-tolyl)phosphine and 68.7 mg of 2-tributylstannyl oxazole (compound 13) were successively added to the reaction flask. Then, 2 mL of chlorobenzene was added dropwise to the reaction flask. After stirring evenly at room temperature, argon was introduced. After 20 minutes of aeration, the reaction was heated to 80 °C for 2 hours. Post-treatment of the reaction: The reaction was restored to room temperature, and column chromatography was directly used for separation and purification. The eluent was dichloromethane and petroleum ether. The obtained compound was recrystallized in methanol to obtain the target small molecule acceptor material A6.

[0074] Test Example Photovoltaic Performance of Target Small Molecule Acceptor Material in Organic Solar Cells

[0075] The structural formula of the donor material PM6 used below is:

[0076]

[0077] 1.1 Study on the Photovoltaic Performance of Target Small Molecule Acceptor Material A1 in Organic Solar Cells

[0078] Fabricate a normal-structure organic solar cell device with PM6 as the donor material and A1 as the acceptor material. The mass ratio of the donor material to the acceptor material is 1:1.2, the processing solvent is chloroform, and the device structure is: ITO / PEDOT:PSS / PM6:small molecule acceptor material / PFNBr / Ag. Through the characterization of the device, for the photovoltaic device based on PM6:A1, the energy conversion efficiency is 7.69%, where the short-circuit current density (Jsc) is 15.67 mA cm -2 , the open-circuit voltage (Voc) is 0.928 V, and the fill factor (FF) is 55.84%.

[0079] 1.2 Research goal: Photovoltaic performance of small molecule acceptor material A2 in organic solar cells

[0080] Fabricate a normal-structure organic solar cell device with PM6 as the donor material and A2 as the acceptor material. The mass ratio of the donor material to the acceptor material is 1:1.2, the processing solvent is chloroform, and the device structure is: ITO / PEDOT:PSS / PM6:small molecule acceptor material / PFNBr / Ag. Through the characterization of the device, for the photovoltaic device based on PM6:A2, the energy conversion efficiency is 8.24%, where the short-circuit current density (Jsc) is 16.01 mA cm -2 , the open-circuit voltage (Voc) is 0.976 V, and the fill factor (FF) is 52.72%.

[0081] 1.3 Research goal: Photovoltaic performance of small molecule acceptor material A3 in organic solar cells

[0082] Fabricate a normal-structure organic solar cell device with PM6 as the donor material and A3 as the acceptor material. The mass ratio of the donor material to the acceptor material is 1:1.2, the processing solvent is chloroform, and the device structure is: ITO / PEDOT:PSS / PM6:small molecule acceptor material / PFNBr / Ag. Through the characterization of the device, for the photovoltaic device based on PM6:A3, the energy conversion efficiency is 7.38%, where the short-circuit current density (Jsc) is 15.36 mA cm -2 , the open-circuit voltage (Voc) is 0.928 V, and the fill factor (FF) is 52.26%.

[0083] 1.4 Research goal: Photovoltaic performance of small molecule acceptor material A4 in organic solar cells

[0084] To fabricate a normal - configuration organic solar cell device, PM6 is used as the donor material and A4 as the acceptor material. The mass ratio of the donor material to the acceptor material is 1:1.2, and the processing solvent is chloroform. The device structure is: ITO / PEDOT:PSS / PM6:small - molecule acceptor material / PFNBr / Ag. Through the characterization of the device, for the PM6:A4 - based photovoltaic device, the energy conversion efficiency is 8.80%, where the short - circuit current density (Jsc) is 16.49 mA cm -2 , the open - circuit voltage (Voc) is 0.948 V, and the fill factor (FF) is 56.30%.

[0085] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An organic conjugated small molecule material with a cyanide-containing indanone end group, Characterized in that, The structural formula is as shown in Formula I: Formula Ⅰ.

2. An organic conjugated small molecule material with a cyanide-containing indanone end group, Characterized in that, The structural formula is as shown in Formula II: Formula II.

3. An organic solar cell, Characterized in that, The photovoltaic material of the solar cell contains the organic conjugated small molecule material described in Claim 1 or 2.

4. The organic solar cell according to Claim 3, Characterized in that, The organic conjugated small molecule material is used as an active layer acceptor material for light capture in the solar cell.

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