Seven-fused-ring small molecule compound containing deuterium atoms on side chain and preparation method of seven-fused-ring small molecule compound

Abstract

The invention provides a hepta-fused ring small molecule compound with a side chain containing deuterium atoms and a preparation method. In the structural formula # imgabs0, R1 and R2 are respectively independent deuterium atom-containing straight chain alkyl, branched chain alkyl, alkoxy, alkyl substituted phenyl, alkoxy substituted phenyl, alkyl substituted thienyl or alkoxy substituted thienyl with the carbon atom number of 1-20; a1 and A2 are respectively independent power-drawing sub-units. The compound can be used for an efficient organic photovoltaic cell, the non-radiative energy loss of a material can be effectively regulated and controlled by utilizing a heavy atom substitution effect, and the photoelectric conversion efficiency of a device is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic functional materials and relates to a heptad-fused-ring small molecule compound, and specifically relates to a heptad-fused-ring small molecule compound having a deuterium atom in the side chain and a preparation method thereof. Background Art

[0002] Solar cells are devices that convert sunlight into electricity. Currently, the most widely commercially used solar cells are primarily made from inorganic materials such as silicon. However, these cells are complex to manufacture, heavy, energy-intensive, and environmentally polluting. Organic solar cells, with their diverse molecular structures, lightweight, flexible, translucent properties, and the ability to fabricate them over large areas and with flexible printing, are expected to overcome the limitations of traditional solar cells, driving the advancement of clean energy technologies and further expanding their application scenarios.

[0003] After years of development, organic solar cells have made significant progress. Currently, small-area cells (<1cm 2 ) has reached a photoelectric conversion efficiency of over 20%. These exciting advances have been made thanks to a deeper understanding of the mechanism of organic solar cells, morphology optimization and control, regulation of the performance of various interfaces of the cell, and the continuous emergence of novel electron donor and acceptor materials.

[0004] In particular, in 2015, Professor Zhan Xiaowei of Peking University reported an acceptor-donor-acceptor (ADA) type small molecule acceptor represented by ITIC [Advanced Material. 2015, 27(7): 1170-1174], and in 2019, Professor Zou Yingping of Central South University reported an acceptor-donor-acceptor-donor-acceptor (A-DA'DA) type small molecule acceptor represented by Y6 [Joule, 2019, 3(4): 1140-1151], which significantly improved the performance of organic solar cells. These conjugated molecules have the advantages of wide absorption spectrum, high electron mobility, and easy structural control. They can effectively adjust the absorption spectrum, molecular energy level, and active layer morphology. They can also effectively separate photogenerated excitons under a small driving force and suppress the recombination of electrons and holes in the device. Compared with batteries with fullerene as acceptor, they achieve a simultaneous improvement in open circuit voltage, short circuit current density, and fill factor.

[0005] Despite significant breakthroughs in the efficiency of organic solar cells, there's still a significant gap compared to newer photovoltaic cells like perovskites. Research has shown that the short-circuit current density and fill factor of organic solar cells are comparable to those of perovskites, but their open-circuit voltage is lower, which is related to their significant voltage energy loss. Suppressing energy loss in organic solar cells through molecular design has become a key research focus for further improving their performance.

[0006] Heavy atom substitution, particularly replacing a light-weight element with its heavier isotope or a heavier element from the same group, has become an effective means of improving the quantum efficiency of organic light-emitting materials. In the field of organic photovoltaic materials, heavy atoms such as selenium, silicon, and germanium have been tried in conjugated small molecules and polymers. There have also been reports of introducing deuterium atoms into fullerene acceptors [Organicletters, 2013, 15, 5674] and conjugated polymer donors [Nature Communications, 2014, 5, 4180], but these have not significantly improved cell efficiency.

[0007] There are reports of deuteration of the backbone of A-DA'DA type small molecule receptors [Angew.Chem.Int.Ed., 2024, 63, e202316227], which effectively reduced the non-radiative energy loss of the device and improved the photoelectric conversion efficiency, demonstrating the effectiveness of backbone deuteration in improving the performance of A-DA'DA type receptor molecules. However, there are no reports of introducing deuterium atoms into the side chains of ADA type fused ring small molecule electron receptors and improving their performance. Summary of the Invention

[0008] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a seven-ring fused small molecule compound with a side chain containing a deuterium atom and a preparation method, so as to solve the technical problem in the existing technology that the photoelectric conversion efficiency needs to be further reduced.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A seven-ring fused small molecule compound containing a deuterium atom in the side chain, the structural formula of the compound is:

[0011]

[0012] Where:

[0013] R1 and R2 are independently a linear alkyl group, a branched alkyl group, an alkoxy group, an alkyl-substituted phenyl group, an alkoxy-substituted phenyl group, an alkyl-substituted thienyl group or an alkoxy-substituted thienyl group having 1 to 20 carbon atoms and containing a deuterium atom;

[0014] A1 and A2 are independent pull electronic units.

[0015] The present invention also has the following technical features:

[0016] The R1 and R2 are respectively 4-alkylphenyl groups with 1 to 20 carbon atoms and substituted with deuterium atoms.

[0017] Or R1 and R2 are respectively straight-chain alkyl groups with 1 to 20 carbon atoms substituted with deuterium atoms.

[0018] Or R1 and R2 are branched alkyl groups with 1 to 20 carbon atoms substituted with deuterium atoms.

[0019] Or R1 and R2 are each a 5-alkoxythienyl group having 1 to 20 carbon atoms and substituted with a deuterium atom.

[0020] The R1 is a linear alkyl group with 1 to 20 carbon atoms substituted by a deuterium atom, and R2 is a 4-alkylphenyl group with 1 to 20 carbon atoms substituted by a deuterium atom.

[0021] Or R1 is a branched alkyl group with 1 to 20 carbon atoms substituted by a deuterium atom, and R2 is a 4-alkylphenyl group with 1 to 20 carbon atoms substituted by a deuterium atom.

[0022] Alternatively, R1 is a 4-alkylphenyl group having 1 to 20 carbon atoms and substituted with a deuterium atom, and R2 is a 5-alkoxythienyl group having 1 to 20 carbon atoms and substituted with a deuterium atom.

[0023] Alternatively, R1 is a 4-alkylphenyl group having 1 to 20 carbon atoms and substituted with a deuterium atom, and R2 is a 5-alkylthienyl group having 1 to 20 carbon atoms and substituted with a deuterium atom.

[0024] Said A1 and A2 are independently selected from one of the following structural formulas of the pull-down electronic unit:

[0025]

[0026] Where:

[0027] R3 in A1 and A2 is a linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group having 1 to 12 carbon atoms.

[0028] The present invention also protects a method for preparing the above-mentioned heptapyr-fused-ring small molecule compound having a deuterium atom in the side chain, the synthetic route of which is:

[0029]

[0030] The method comprises the following steps:

[0031] Step 1: react the monomer compounds corresponding to the R1 and R2 groups with bromine and deuterium atoms with n-hexyllithium at -78°C in anhydrous and oxygen-free conditions for 2 hours, then add diethyl 2,5-bis(thieno[3,2-B]thiophen-2-yl)terephthalate, warm to room temperature and continue to react for 2 hours, extract and dry, and then recrystallize and purify; and complete the ring-closure reaction in an acidic environment, and continue to recrystallize and purify to obtain the IDTT intermediate containing deuterated R1 and R2 groups.

[0032] Step 2: The IDTT intermediate is reacted with n-hexyllithium at -78°C in anhydrous and oxygen-free conditions for 2 hours. N,N-dimethylformamide is then added, the temperature is raised to room temperature, and the reaction is continued for 2 hours. After extraction and drying, the IDTT-CHO intermediate containing deuterated R1 and R2 groups is purified by column chromatography.

[0033] Step 3: Add pyridine to the IDTT-CHO intermediate and 4-6 times the amount of the monomer compound corresponding to the electron-pulling unit A1 or A2 in chloroform solution and reflux for 6-12 hours, precipitate with methanol, perform silica gel column chromatography, and elute with chloroform to obtain the product.

[0034] Alternatively, the IDTT-CHO intermediate and a monomer compound corresponding to the electron-withdrawing unit A1 in an amount of 1 to 1.5 times are added with pyridine in a chloroform solution and refluxed for 8 to 12 hours, purified by column chromatography to obtain an intermediate, which is then added with a monomer compound corresponding to the electron-withdrawing unit A2 in an amount of 2 to 4 times the amount in a chloroform solution and refluxed for 6 to 12 hours, precipitated with methanol, subjected to silica gel column chromatography, and eluted with chloroform to obtain a heptad fused ring small molecule compound containing a deuterium atom in the side chain.

[0035] The heptapyr-fused-ring small molecule compound containing deuterium atoms in the present invention is used as an n-type material in a photoactive layer in an organic photovoltaic (OPV) device.

[0036] Compared with the prior art, the present invention has the following technical effects:

[0037] (I) The compounds of the present invention can be used in high-efficiency organic photovoltaic cells. By utilizing the heavy atom substitution effect, the non-radiative energy loss of the material can be effectively regulated, thereby improving the photoelectric conversion efficiency of the device.

[0038] (II) The compound of the present invention has a wide adjustable spectral absorption, a strong absorption coefficient, good charge transport performance and a suitable molecular orbital energy level, and further suppresses non-radiative energy loss through deuterium atom substitution.

[0039] (III) The compound of the present invention is blended with a wide-bandgap polymer electron donor to produce a single-layer binary photovoltaic device, which can effectively improve the photoelectric conversion efficiency. Wide-bandgap polymer electron donors include DA-type donor polymers based on bisfluorobenzotriazole, DA-type donor polymers based on thiazolothiazole, and DA-type donor polymers based on benzo[1,2-C:4,5-C']dithiophene-4,8-dione. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is the mass spectrum of compound A1.

[0041] Figure 2 is the UV-vis absorption spectrum of compound A1.

[0042] Figure 3 is the electrochemical diagram of compound A1.

[0043] Figure 4 JV characteristic curve of organic solar cell device based on compound A1.

[0044] Figure 5 is the mass spectrum of compound A2.

[0045] Figure 6 is the UV-vis absorption spectrum of compound A2.

[0046] Figure 7 This is the electrochemical diagram of compound A2.

[0047] Figure 8 JV characteristic curve of the organic solar cell device based on compound A2.

[0048] The specific contents of the present invention are further explained in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0049] It should be noted that, unless otherwise specified, all materials and instruments in the present invention are those known in the art.

[0050] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0051] Example 1:

[0052] This example provides a method for preparing a small molecule compound having a heptad-fused ring with a deuterium atom in the side chain. The compound is compound 7 of this example, denoted as compound A1. The synthetic route of the compound is:

[0053]

[0054] Preparation of Compound 2: Tetradeuterium-substituted p-bromobenzene was placed in an oxygen-free reactor at -78°C with tetrahydrofuran as the solvent and reacted with n-butyllithium for 2 hours. Then, n-hexyl bromide was added, and the mixture was slowly warmed to room temperature and allowed to react for 2 hours. After extraction and drying, the mixture was purified by high vacuum distillation to obtain a colorless oily tetradeuterium-substituted p-hexylbromobenzene, Compound 2.

[0055] The method comprises the following steps:

[0056] Step 1: Add 5.06 g / 20 mmol of tetradeuterium-substituted p-hexylbromobenzene liquid (i.e., compound 2) and 30 ml of anhydrous tetrahydrofuran to a 100 ml three-necked flask. Place in a -78 ° C cold trap under nitrogen protection, then add 11.45 ml of n-hexyllithium (2.5 M), react for 2 h, and then add diethyl 2,5-bis(thieno[3,2-B]thiophen-2-yl)terephthalate (i.e., compound 3).

[0057] The reaction mixture was stirred for 2 h, and the temperature was slowly raised to room temperature after cooling. The reaction was continued for 2 h. The product was extracted, washed, and recrystallized (tetrahydrofuran / isopropanol). The purified product was dissolved in 20 ml of ethyl acetate, and then 6 ml of glacial acetic acid and 2 ml of concentrated sulfuric acid were added to react for 30 min. The product was then purified by recrystallization (tetrahydrofuran / ethanol) to obtain 2.54 g of an IDTT intermediate containing deuterated R1 and R2 groups, i.e., compound 4, with a liquid content of >99% and a yield of 73%.

[0058] Step 2: Compound 4 0.75 g / 0.724 mmol, anhydrous tetrahydrofuran 10 ml, n-hexane 3 ml, and tetramethylethylenediamine 0.287 ml were added to a 100 ml three-necked flask. The mixture was placed in a -78 ° C cold trap under nitrogen protection, and then 1 ml of n-hexyllithium (2.5 M) was added. After reacting for 2 h, 1 ml of N, N-dimethylformamide was added. The refrigeration was turned off and the temperature was slowly raised to room temperature. The reaction was continued for 2 h. The product was extracted, washed, and purified by column chromatography (ethyl acetate: n-hexane = 60:1) to obtain 0.64 g of IDTT-CHO intermediate containing deuterated R1 and R2 groups, namely compound 5, with a liquid content of >99% and a yield of 86%.

[0059] The structural characterization results of compound 5 in this example are:

[0060] 1H NMR (500MHz, CDCl3, ppm) δ9.89 (s, 1H), 7.94 (s, 1H), 7.61 (s, 1H), 2.69-2.48 (m, 4H), 1.43 (d, J = 146.8Hz, 13H), 1.29-1.13 (m, 4H), 0.87 (s, 6H).

[0061] Step three, take 100 mg / 0.092 mmol of the above compound 5 and 107 mg / 0.5529 mmol of compound 6, place them in a 100 ml three-necked flask, dissolve them in 20 ml of chloroform, then add 0.5 ml of pyridine, heat and reflux for 6 h, stop heating, cool, extract, wash, add the extract dropwise to methanol for precipitation, filter and purify the resulting solid by column chromatography, elute with chloroform to obtain 105 mg of black solid, which is compound 7, with a yield of 82% and a liquid content of >99%.

[0062] The structural characterization results of compound 7 in this example are:

[0063] The mass spectrum of compound 7 in this example is as follows Figure 1 shown.

[0064] 1 H NMR (500MHz, CDCl3, ppm) δ8.85 (s, 2H), 8.53 (dd, J = 9.9, 6.3Hz, 2H), 8.23 ​​(s, 2H), 7.78- 7.59(m,4H),2.63-2.52(m,8H),1.59(s,10H),1.41-1.20(m,27H),0.95-0.79(m,13H).

[0065] 13 C NMR(125MHz, CDCl3)δ:185.78,158.24,155.89,153.61,147.80,147.64,143.96 ,142.45,139.48,138.64,138.44,137.42,137.06,136.69,134.50,128.50,127. 44,121.84,118.68,115.10,114.93,114.23,114.12,112.76,112.62,77.29,77.03,76.78,69.95,63.17,35.50,31.70,31.23,29.72,29.18,22.59,14.08,0.01.

[0066] From the above characterization results, it can be seen that compound 7 of this example is recorded as the target product compound A1.

[0067] The UV-visible-near-infrared absorption spectra of compound A1 solution and film are as follows: Figure 2 shown.

[0068] The electrochemical data of compound A1 are as follows Figure 3 shown.

[0069] Photovoltaic performance research:

[0070] The compound A1 of this example is used as an n-type material in a photoactive layer in an organic photovoltaic (OPV) device.

[0071] The cell structure of ITO / ZnO / PM6: acceptor material / MoO3 / Al is used to make PM6 and acceptor material into polymer photovoltaic cells with an effective area of ​​0.16cm 2 , under the simulated sunlight source (Oriel model91192; 100mW / cm 2 ) and the device's energy conversion efficiency (PCE) was measured to be 11.95%. The JV curve is shown in the figure below. Figure 4 shown.

[0072] The photoelectric performance data of the device based on compound A1 are shown in Table 1.

[0073] Table 1 Photoelectric performance data of devices based on compound A1

[0074]

[0075] Note: a) The data is the average of 10 devices. b) The optimal values ​​are in brackets.

[0076] Example 2:

[0077] This example provides a method for preparing a small molecule compound having a heptad-fused ring with a deuterium atom in the side chain. The compound is compound 7 of this example, denoted as compound A2. The synthetic route of the compound is:

[0078]

[0079] Preparation of Compound 2: Tetradeuterium-substituted p-bromobenzene was placed in an oxygen-free reactor at -78°C and reacted with n-butyllithium in tetrahydrofuran for 2 hours. Then, n-hexyl bromide was added, and the temperature was slowly warmed to room temperature and allowed to react for 2 hours. After extraction and drying, high vacuum distillation and purification afforded a colorless oily tetradeuterium-substituted p-hexylbromobenzene, Compound 2.

[0080] The method comprises the following steps:

[0081] Step 1: Add 5.06 g / 20 mmol of tetradeuterium-substituted p-hexylbromobenzene liquid (i.e., compound 2) and 30 ml of anhydrous tetrahydrofuran to a 100 ml three-necked flask. Place in a -78 ° C cold trap under nitrogen protection, then add 11.45 ml of n-hexyllithium (2.5 M), react for 2 h, and then add diethyl 2,5-bis(thieno[3,2-B]thiophen-2-yl)terephthalate (i.e., compound 3).

[0082] The reaction mixture was stirred for 2 h, and the temperature was slowly raised to room temperature after cooling. The reaction was continued for 2 h. The product was extracted, washed, and recrystallized (tetrahydrofuran / isopropanol). The purified product was dissolved in 20 ml of ethyl acetate, and then 6 ml of glacial acetic acid and 2 ml of concentrated sulfuric acid were added to react for 30 min. The product was then purified by recrystallization (tetrahydrofuran / ethanol) to obtain 2.54 g of an IDTT intermediate containing deuterated R1 and R2 groups, i.e., compound 4, with a liquid content of >99% and a yield of 73%.

[0083] Step 2: Compound 4 0.75 g / 0.724 mmol, anhydrous tetrahydrofuran 10 ml, n-hexane 3 ml, and tetramethylethylenediamine 0.287 ml were added to a 100 ml three-necked flask. The mixture was placed in a -78 ° C cold trap under nitrogen protection, and then 1 ml of n-hexyllithium (2.5 M) was added. After reacting for 2 h, 1 ml of N, N-dimethylformamide was added. The refrigeration was turned off and the temperature was slowly raised to room temperature. The reaction was continued for 2 h. The product was extracted, washed, and purified by column chromatography (ethyl acetate: n-hexane = 60:1) to obtain 0.64 g of IDTT-CHO intermediate containing deuterated R1 and R2 groups, namely compound 5, with a liquid content of >99% and a yield of 86%.

[0084] The structural characterization results of compound 5 in this example are:

[0085] 1 H NMR (500MHz, CDCl3, ppm) δ: 9.89 (s, 1H), 7.94 (s, 1H), 7.61 (s, 1H), 2.69-2.48 (m, 4H), 1.43 (d, J = 146.8Hz, 13H), 1.29-1.13 (m, 4H), 0.87 (s, 6H).

[0086] Step 3: Take 100 mg / 0.092 mmol of the above compound 5 and 107 mg / 0.5529 mmol of compound 6, place them in a 100 ml three-necked flask, dissolve them in 20 ml of chloroform, then add 0.5 ml of pyridine, heat and reflux for 6 h, stop heating, cool, extract, wash, and add the extract dropwise to methanol for precipitation. After filtering, purify the resulting solid by column chromatography and elute with chloroform to obtain 97 mg of black solid, which is compound 7, with a yield of 80% and a liquid content of >99%.

[0087] The structural characterization results of compound 7 in this example are:

[0088] The mass spectrum of compound 7 in this example is as follows Figure 5 shown.

[0089] 1 H NMR (500MHz, CDCl3, ppm) δ: 8.86 (s, 2H), 8.69 (d, J = 7.6Hz, 2H), 8.22 (s, 2H), 7.92 (d, J = 6.8Hz, 2H), 7.83-7. 70(m,4H),7.63(s,2H),2.71-2.45(m,8H),1.65-1.44(m,27H),1.37-1.15(m,29H),0.86(t,J=6.7Hz,14H).

[0090] 13 C NMR(125MHz, CDCl3)δ:185.78,158.24,155.89,153.61,147.80,147.64,143.96 ,142.45,139.48,138.64,138.44,137.42,137.06,136.69,134.50,128.50,127. 44,121.84,118.68,115.10,114.93,114.23,114.12,112.76,112.62,77.29,77.03,76.78,69.95,63.17,35.50,31.70,31.23,29.72,29.18,22.59,14.08,0.01.

[0091] From the above characterization results, it can be seen that compound 7 of this example is recorded as the target product compound A2.

[0092] The UV-visible-near-infrared absorption spectra of compound A1 solution and film are as follows: Figure 6 shown.

[0093] The electrochemical data of compound A1 are as follows Figure 7 shown.

[0094] Photovoltaic performance research:

[0095] The compound A2 of this example is used as an n-type material in a photoactive layer in an organic photovoltaic (OPV) device.

[0096] Using the cell structure of ITO / ZnO / PBDB-T: acceptor material / MoO3 / Al, PM6 and the acceptor material are made into polymer photovoltaic cells with an effective area of ​​0.16cm 2 , under the simulated sunlight source (Oriel model91192; 100mW / cm 2 ) and the device's energy conversion efficiency (PCE) was measured to be 10.93%. Figure 8 shown.

[0097] The photoelectric performance data of the device based on compound A2 are shown in Table 2.

[0098] Table 2 Photoelectric performance data of devices based on compound A2

[0099]

[0100] Note: a) The data is the average of 10 devices. b) The optimal values ​​are in brackets.

[0101] Example 3:

[0102] This example provides a method for preparing a small molecule compound having a heptad-fused ring with a deuterium atom in the side chain. The compound is compound 7 of this example, denoted as compound A3. The synthetic route of the compound is:

[0103]

[0104] The method comprises the following steps:

[0105] Step 1: 5.07 g / 18 mmol of the monomer compound corresponding to the R1 and R2 groups with bromine and deuterium atoms (i.e., compound 2) and 30 ml of anhydrous tetrahydrofuran were added to a 100 ml three-necked flask, and the mixture was placed in a -78 ° C cold trap under nitrogen protection. 11.45 ml of n-hexyllithium (2.5 M) was added, and after reacting for 2 h, compound 1 (1.5 g / 3.2 mmol) was added. The refrigeration was turned off and the temperature was slowly raised to room temperature. The reaction was continued for 2 h. The product was extracted, washed, and recrystallized (tetrahydrofuran / isopropanol). The purified product was dissolved in 20 ml of ethyl acetate, and then 6 ml of glacial acetic acid and 2 ml of concentrated sulfuric acid were added to react for 30 min. The mixture was then purified by recrystallization (tetrahydrofuran / ethanol) to obtain 2.1 g of compound 3 with a liquid content of >99% and a yield of 64%.

[0106] Step 2: Compound 3 (0.75 g / 0.701 mmol), 10 ml of anhydrous tetrahydrofuran, 3 ml of n-hexane, and 0.287 ml of tetramethylethylenediamine were added to a 100 ml three-necked flask. The mixture was placed in a -78 ° C cold trap under nitrogen protection, and 1 ml of n-hexyllithium (2.5 M) was added. After reacting for 2 h, 1 ml of N, N-dimethylformamide was added. The refrigeration was turned off and the temperature was slowly raised to room temperature. The reaction was continued for 2 h. The product was extracted, washed, and purified by column chromatography (ethyl acetate: n-hexane = 60:1) to obtain 0.58 g of IDTT-CHO intermediate containing deuterated R1 and R2 groups, namely compound 5, with a liquid content of >99% and a yield of 84%.

[0107] The structural characterization results of compound 5 in this example are:

[0108] 1 H NMR (500MHz, CDCl3, ppm) δ: 9.91 (s, 0H), 7.91 (d, J = 0.6Hz, 1H), 2.46 (t, J = 8.0Hz, 2H), 2.19-2.08 (m, 1H), 1.94-1.84 (m, 1H), 1.66-1.48 (m, 2H),

[0109] 1.47-1.35(m,3H),1.38-1.31(m,2H),1.34-1.30(m,2H),1.31(s,1H),1.33-1.26(m,1H).

[0110] Step 3: Take 100 mg / 0.092 mmol of the above compound 4 and 100 mg / 0.52 mmol of compound 5, place them in a 100 ml three-necked flask, dissolve them in 20 ml of chloroform, then add 0.5 ml of pyridine, heat and reflux for 6 h, stop heating, cool, extract, wash, add the extract dropwise to methanol for precipitation, filter and purify the resulting solid by column chromatography, elute with chloroform to obtain 94 mg of black solid, which is compound 7, with a yield of 82% and a liquid content of >99%.

[0111] The structural characterization results of compound 7 in this example are:

[0112] 1H NMR (500MHz, CDCl3, ppm) δ: 8.27 (d, J = 0.6Hz, 1H), 8.17 (dd, J = 8.0, 1.7Hz, 1H), 8.13(s,1H),7.99(dd,J=7.8,1.7Hz,1H),7.65(td,J=7.9,1.7Hz,1H),7.59(td ,J=7.8,1.6Hz,1H),2.46(t,J=8.0Hz,4H),2.18-2.08(m,2H),1.93-1.83(m,2H ),1.66-1.48(m,4H),1.47-1.35(m,5H),1.38-1.30(m,7H),1.33-1.25(m,4H).

[0113] 13 C NMR(125MHz, CDCl3)δ:187.71,166.27,146.48,146.33,146.21,141.95,14 1.84,139.70,138.51,137.65,137.40,135.38,135.06,132.68,130.51,129 .05,128.63,128.57,127.55,127.37,127.17,126.51,115.09,114.40,113.61,72.62,51.98,35.51,35.40,30.96,29.72,29.62,29.51,24.88,23.73.

[0114] From the above characterization results, it can be seen that compound 7 of this example is the target product compound A3.

Claims

1. A small molecule compound having a heptad fused ring with a deuterium atom in the side chain, characterized in that: The structural formula of the compound is: Where: R1 and R2 are independently a linear alkyl group, a branched alkyl group, an alkoxy group, an alkyl-substituted phenyl group, an alkoxy-substituted phenyl group, an alkyl-substituted thienyl group or an alkoxy-substituted thienyl group having 1 to 20 carbon atoms and containing a deuterium atom; A1 and A2 are independent pull electronic units.

2. The heptapyr-fused-ring small molecule compound having a deuterium atom in the side chain according to claim 1, wherein: Said R1 and R2 are respectively 4-alkylphenyl groups with 1 to 20 carbon atoms substituted with deuterium atoms; Or R1 and R2 are each a linear alkyl group having 1 to 20 carbon atoms substituted with a deuterium atom; Or R1 and R2 are branched alkyl groups with 1 to 20 carbon atoms substituted with deuterium atoms. Or R1 and R2 are each a 5-alkoxythienyl group having 1 to 20 carbon atoms and substituted with a deuterium atom.

3. The heptapyr-fused-ring small molecule compound having a deuterium atom in the side chain according to claim 1, wherein: The R1 is a linear alkyl group with 1 to 20 carbon atoms substituted with a deuterium atom, and R2 is a 4-alkylphenyl group with 1 to 20 carbon atoms substituted with a deuterium atom; Or R1 is a branched alkyl group with 1 to 20 carbon atoms substituted with a deuterium atom, and R2 is a 4-alkylphenyl group with 1 to 20 carbon atoms substituted with a deuterium atom; Or R1 is a 4-alkylphenyl group having 1 to 20 carbon atoms and substituted with a deuterium atom, and R2 is a 5-alkoxythienyl group having 1 to 20 carbon atoms and substituted with a deuterium atom; Alternatively, R1 is a 4-alkylphenyl group having 1 to 20 carbon atoms and substituted with a deuterium atom, and R2 is a 5-alkylthienyl group having 1 to 20 carbon atoms and substituted with a deuterium atom.

4. The heptapyr-fused-ring small molecule compound having a deuterium atom in the side chain according to claim 1, wherein: Said A1 and A2 are independently selected from one of the following structural formulas of the pull-down electronic unit: Where: R3 in A1 and A2 is a linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group having 1 to 12 carbon atoms.

5. A method for preparing a small molecule compound having a heptapyr-fused ring with a deuterium atom in the side chain according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: Step 1: reacting monomer compounds corresponding to R1 and R2 groups with bromine and deuterium atoms with n-hexyllithium at -78°C in anhydrous and oxygen-free conditions for 2 hours, then adding diethyl 2,5-bis(thieno[3,2-B]thiophen-2-yl)terephthalate, heating to room temperature and continuing the reaction for 2 hours, extracting and drying, and then recrystallizing and purifying; completing the ring-closure reaction in an acidic environment, and continuing recrystallizing and purifying to obtain an IDTT intermediate containing deuterated R1 and R2 groups; Step 2: The IDTT intermediate is reacted with n-hexyllithium at -78°C under anhydrous and oxygen-free conditions for 2 hours, and then N,N-dimethylformamide is added. The temperature is raised to room temperature and the reaction is continued for 2 hours. After extraction and drying, the IDTT-CHO intermediate containing deuterated R1 and R2 groups is purified by column chromatography. Step 3: Add pyridine to the IDTT-CHO intermediate and 4-6 times the amount of the monomer compound corresponding to the electron-pulling unit A1 or A2 in a chloroform solution and reflux for 6-12 hours, precipitate with methanol, perform silica gel column chromatography, and elute with chloroform to obtain the product; Alternatively, the IDTT-CHO intermediate and a monomer compound corresponding to the electron-withdrawing unit A1 in an amount of 1 to 1.5 times are added with pyridine in a chloroform solution and refluxed for 8 to 12 hours, purified by column chromatography to obtain an intermediate, which is then added with a monomer compound corresponding to the electron-withdrawing unit A2 in an amount of 2 to 4 times the amount in a chloroform solution and refluxed for 6 to 12 hours, precipitated with methanol, subjected to silica gel column chromatography, and eluted with chloroform to obtain a heptad fused ring small molecule compound containing a deuterium atom in the side chain.

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