A type of β-tetrasubstituted porphyrin organic photovoltaic material and its preparation method and application

Abstract

The present invention belongs to the field of organic small molecule photovoltaic materials and discloses a class of β-tetrasubstituted porphyrin organic photovoltaic materials, their preparation methods, and applications. The β-tetrasubstituted porphyrin photovoltaic material described in the present invention uses the porphyrin ring as the central power-donating unit, and connects power-absorbing units at the four symmetrical β positions of tetraphenylporphyrin to synthesize the target molecule, forming a push-pull electron effect, which can effectively enhance intramolecular charge transfer and broaden absorption. By changing the porphyrin ring and the side groups of the power-absorbing units, the absorption and energy levels of the molecule are effectively adjusted, achieving the purpose of further optimizing the material performance. The present invention demonstrates the modifiability of the porphyrin β site and provides a new direction for the molecular design of β-site porphyrin materials for organic solar cells.

Description

Technical Field

[0001] The present invention belongs to the field of organic small molecule photovoltaic materials, and in particular relates to a type of β-position tetrasubstituted porphyrin organic photovoltaic material and a preparation method and application thereof. Background Art

[0002] Traditional fossil energy sources face a severe energy depletion crisis, while also causing significant environmental pollution. Solar energy is abundant, easily accessible, clean, and green, and organic solar cells, which convert solar energy into electricity, have been widely researched. Organic solar cells achieve photoelectric conversion by absorbing photons using organic photoactive materials. Single-junction device efficiencies now exceed 19%, and certified tandem cell efficiencies exceed 20%. Their diverse material structures allow for solution processing and large-scale roll-to-roll printing, facilitating the design of low- or non-toxic devices. They are also flexible and lightweight, suitable for wearable applications, and can be made into semi-transparent devices for use in green buildings, offering significant potential for application. Therefore, the development of efficient and stable active materials is currently a key focus of organic solar cell research.

[0003] Porphyrin and its derivatives have a wide absorption region and a high extinction coefficient, and their molecular tunability is high. The photoelectric properties can be adjusted by introducing functional groups on the periphery of the porphyrin or different metals in the center. In addition, due to their large conjugated plane, strong electron-donating ability, and good stability, porphyrin-based donor materials have currently achieved efficiencies exceeding 12%. Most high-efficiency porphyrin materials use pyrrolopyrrole dione as the electron-withdrawing unit and extend the conjugation at the meso position. However, β-substituted porphyrins exhibit unique electron transfer properties and have important research significance in the field of organic solar cells. However, β-modified porphyrin materials are rarely used in organic solar cells, with only one patent (Chinese invention authorization right CN113105463 B) achieving a low photoelectric conversion efficiency (PCE) of 3.03%. Summary of the Invention

[0004] To address the shortcomings and deficiencies of the prior art, the primary objective of the present invention is to provide a class of β-tetrasubstituted porphyrin organic photovoltaic materials. This material synthesizes a donor material using a porphyrin ring as the charge-donating unit and triple-bonding charge-withdrawing units at the porphyrin's four symmetrical β positions. The triple-bonding enhances molecular planarity, facilitating charge transfer. Simultaneously, by varying the porphyrin ring and the side groups of the charge-withdrawing units, the absorption and energy levels of the molecule are effectively modulated, further optimizing the material's performance.

[0005] Another object of the present invention is to provide a method for preparing a class of β-tetrasubstituted porphyrin organic photovoltaic materials.

[0006] Another object of the present invention is to provide an application of the above-mentioned β-tetrasubstituted porphyrin organic photovoltaic material in an organic solar cell.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A class of β-tetrasubstituted porphyrin organic photovoltaic materials with the following chemical structure:

[0009]

[0010] Wherein, A is an electron-withdrawing group having a conjugated structure; and R is hydrogen or an alkyl or alkoxy group containing 1 to 4 carbon atoms.

[0011] Preferably, A is one of the following structural units:

[0012]

[0013] Preferably, R is at least one of an H atom, a methyl group, a methoxy group, an isopropyl group, an n-butyl group, and a tert-butyl group.

[0014] The preparation method of the above-mentioned β-tetrasubstituted porphyrin organic photovoltaic material comprises the following steps:

[0015] (1) dissolving compound (I) in an organic solvent and reacting with N-bromosuccinimide (NBS) at 60-70° C. for 3-5 hours to obtain a compound represented by formula (II);

[0016]

[0017] (2) dissolving compound (II) in an organic solvent, adding zinc acetate and reacting at 60-70°C for 8-15 hours to obtain compound (III);

[0018]

[0019] (3) dissolving compound (III) in an organic solvent, adding triisopropylsilyl acetylene, and reacting at 60-70°C for 18-30 hours in the presence of a catalyst to obtain an intermediate product (IV);

[0020] (4) The intermediate product (IV) is dissolved in an organic solvent, and tetrabutylammonium fluoride (THF) solution is added and stirred at room temperature for 5-30 minutes. The reaction is quenched by adding water, extracted, and dried by spin drying and then directly used in the next reaction;

[0021] (5) The spin-dried product in step (4) and the diketopyrrolidine monomer of the receptor molecule A are heated under reflux in an organic solvent in the presence of a catalyst for 48-72 hours to obtain the target compound.

[0022] Wherein, R and A have the same definitions as above.

[0023] Preferably, the organic solvent in step (1) is one of chloroform and dichloromethane;

[0024] Preferably, the molar ratio of compound (I) to N-bromosuccinimide in step (1) is 1:5-1:7;

[0025] Preferably, the organic solvent in step (2) is a mixed solution of chloroform and methanol; the molar amount of chloroform is 3000-4000 times the molar amount of compound (II), and the volume ratio of chloroform to methanol is 6:1-3:1;

[0026] Preferably, the molar ratio of compound (II) to zinc acetate in step (2) is 1:5-1:8;

[0027] Preferably, the organic solvent in step (3) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 1000-3000 times the molar amount of compound (III), and the volume ratio of tetrahydrofuran to triethylamine is 2:1-5:1;

[0028] Preferably, the molar ratio of compound (III) to triisopropylsilyl acetylene in step (3) is 1:8-1:12;

[0029] Preferably, the catalyst in step (3) is bis(triphenylphosphine)palladium dichloride and cuprous iodide. The molar amount of both is 0.15 times the molar amount of compound (III);

[0030] Preferably, the organic solvent in step (4) is tetrahydrofuran; the molar amount of tetrahydrofuran is 1000-3000 times the molar amount of compound (IV);

[0031] Preferably, the molar ratio of the intermediate product (IV) to tetrabutylammonium fluoride in step (4) is 1:6-1:8;

[0032] Preferably, the molar ratio of the spin-dried product in step (5) to the diketopyrrolopyrrole monomer of the receptor molecule A is 1:6-1:8;

[0033] The organic solvent in step (5) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 1000-3000 times the molar amount of the spin-dried product, and the volume ratio of tetrahydrofuran to triethylamine is 2:1-5:1

[0034] Preferably, the catalyst in step (5) is tetrakis(triphenylphosphine)palladium and cuprous iodide; the molar amount of both is 0.15 times the molar amount of the spin-dried product.

[0035] The application of the β-tetrasubstituted porphyrin organic photovoltaic material is preferably in organic solar cells.

[0036] The above-mentioned β-position tetrasubstituted porphyrin organic photoelectric material is used as a donor photovoltaic material, with the porphyrin ring as the electron-donating group and the electron-absorbing units connected by triple bonds to form an effective push-pull electron effect to regulate molecular absorption and energy levels.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] (1) The present invention uses triple bonds to connect electron-withdrawing units at the four symmetrical β positions of porphyrin to maintain the molecular planar structure, effectively increase the molecular conjugation and intramolecular charge transfer (ICT), red-shift and broaden the absorption of the material, and enhance the light absorption capacity of the active layer material.

[0039] (2) The present invention changes the electron-withdrawing ability of the electron-withdrawing group conjugated with porphyrin, effectively adjusting the energy level of the material, thereby designing a donor-acceptor material with a better energy level match.

[0040] (3) The present invention changes the length of the side alkyl chain of the porphyrin electron-withdrawing unit, improves the solubility of the molecule, changes the stacking structure of the molecule, and affects the photovoltaic performance of the organic solar cell device prepared later.

[0041] (4) The β-tetrasubstituted porphyrin material designed by the present invention further demonstrates the multi-site modifiability of porphyrin and provides a new direction for the molecular design of β-site porphyrin materials for organic solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the H NMR spectrum of Example 1.

[0043] Figure 2 This is the mass spectrum (MALDI-TOF) of Example 1.

[0044] Figure 3 This is the H NMR spectrum of Example 2.

[0045] Figure 4 This is the mass spectrum (MALDI-TOF) of Example 2.

[0046] Figure 5 The UV-visible absorption spectra of the solution and film of Example 1 are shown.

[0047] Figure 6 The UV-visible absorption spectra of the solution and film of Example 2 are shown.

[0048] Figure 7 The photovoltaic cells prepared from the materials obtained in Examples 1 and 2 were subjected to AM 1.5 and 100 mW / cm 2 Current-voltage curve under light illumination. DETAILED DESCRIPTION

[0049] The present invention will be described in further detail below with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.

[0050] In the examples of the present invention, if the specific conditions are not specified, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. All raw materials and reagents used without specifying the manufacturer are conventional products that can be purchased from the market.

[0051] Example 1

[0052] Preparation of EHDPP-Por molecules: R is a H atom, and the A unit is 2-ethylhexyl-substituted diketopyrrolopyrrole (EHDPP).

[0053] The reaction process of Example 1 is as follows:

[0054]

[0055] (1) Compound 1 (800 mg, 1.3 mmol) and NBS (1.39 g, 7.8 mmol) were added to a two-necked flask, 100 mL of chloroform solution was used as solvent, and the mixture was refluxed at 65°C for 4 hours. The reaction was terminated by TLC plate detection. The solvent was dried on a rotary evaporator and the mixture was purified by silica gel chromatography using petroleum ether and dichloromethane as eluents. Compound 2 (725 mg, yield 60%) was obtained by recrystallization.

[0056] (2) Compound 2 (720 mg, 0.77 mmol) and zinc acetate (706 mg, 3.85 mmol) were added to a 250 mL reaction flask, and a mixed solvent of 100 mL of chloroform and 20 mL of methanol was added. The mixture was refluxed at 65°C overnight. The reaction was terminated by TLC plate detection. The mixture was passed through a short silica gel column with chloroform as the eluent, and recrystallized to obtain compound 3 (612 mg, 80% yield).

[0057] (3) Under argon, compound 3 (600 mg, 0.6 mmol), 50 ml of ultra-dry tetrahydrofuran (THF), and 10 ml of ultra-dry triethylamine (NEt3) were added to a two-necked flask. 63 mg (0.15 eq) of bis(triphenylphosphine)palladium dichloride and 17 mg (0.15 eq) of cuprous iodide were then added. After purging with argon for 10 min, triisopropylsilyl acetylene was introduced using a long needle. The mixture was heated under reflux at 65°C for 24 hours in the dark. After the reaction, the solvent was dried using a rotary evaporator and the mixture was purified by silica gel chromatography using petroleum ether and dichloromethane as eluents. Compound 4 was recrystallized from chloroform and methanol to obtain compound 4 as a green solid (411 mg, 49% yield).

[0058] (4) Compound 4 (400 mg, 0.28 mmol) was dissolved in 10 mL of THF, and tetrabutylammonium fluoride solution (TBAF) (0.8 mL, 1 M in THF) was added. The reaction was allowed to react at room temperature for 5 min, and then quenched with water. The product was extracted with water / chloroform and dried to give compound 5, which was directly used in the next step.

[0059] (5) Under argon protection, compound 5 (0.14 mmol) and compound EHDPP (506 mg, 0.84 mmol) (purchased from Nanjing Zhiyan Technology Co., Ltd.) were added to a 100 mL double-necked round-bottom flask, dissolved in 20 mL THF and 10 ml Et3N ultra-dry solvent, and then tetrakis(triphenylphosphine)palladium (24.3 mg, 0.021 mmol) and cuprous iodide (4 mg, 0.021 mmol) were added. The reaction system was evacuated three times and then reacted at 65 ° C in the dark for 72 hours. After the reaction was completed, the mixture was dried and passed through a silica gel column using petroleum ether and dichloromethane as eluents. GPC column chromatography was performed using THF as eluent, and then recrystallized from chloroform and methanol to obtain the final product EHDPP-Por (272 mg, yield 68%). 1H NMR (400 MHz, CDCl3) δ 8.92 (dd, J = 7.9, 3.7 Hz, 8H), 8.60 (s, 4H), 8.12 (d, J = 7.0 Hz, 8H), 7.78 (t, J = 7.4 Hz, 4H), 7.70 (t, J = 6.8 Hz, 8H), 7.62 (d, J = 5.0 Hz, 4H), 7.29 (d, J = 4.1 Hz, 4H), 7.24 (d, J = 4.9 Hz, 4H), 4.02 (d, J = 7.7 Hz, 16H), 1.96-1.79 (m, 8H), 1.39-1.19 (m, 64H), 0.85 (m, J = 14.0, 9.0, 4.8 Hz, 48H), H NMR spectrum see Figure 1 .

[0060] Matrix-assisted laser desorption ionization time-of-flight mass spectrometry: experimental value 2864.4; calculated value C 172 H 180 N 12 O8S8Zn2865.27, see Figure 2 .

[0061] The porphyrin organic small molecule photovoltaic material prepared in this example was dissolved in chloroform solution at a concentration of (10 -5 -10 -4 mol / L), the UV-visible absorption spectrum of the obtained chloroform solution is shown in Figure 5 .

[0062] The porphyrin organic small molecule photovoltaic material prepared in this example was prepared into a thin film with a thickness of about 70 nm by spin coating. The ultraviolet-visible absorption spectrum of the thin film is shown in FIG. Figure 5 .

[0063] Using the porphyrin molecules of this example as donor materials and the small molecule Y6 (CAS: 2304444-49-1) as the acceptor material, a face-up device was prepared to study photovoltaic performance. The device structure is ITO / PEDOT:PSS / active layer / PFN-Br / Ag, and the mass ratio of the active layer to the acceptor is 1:0.9. The current-voltage curve (JV curve) under illumination is shown in FIG. Figure 7 The device has a photoelectric conversion efficiency of 5.62% and a short-circuit current of 15.66 mA / cm 2 , the open circuit voltage is 0.78V and the fill factor is 45.98%.

[0064] The photoelectric conversion efficiency achieved by the heterojunction cell prepared in this embodiment is the highest photoelectric conversion efficiency achieved by optimizing the donor-acceptor ratio, using an active layer material prepared with a donor-acceptor mass ratio of 1:0.9, and performing thermal annealing.

[0065] Example 2

[0066] Preparation of BODPP-Por molecules: R is a hydrogen atom, and the A unit is 2-butyloctyl-substituted diketopyrrolopyrrole (BODPP).

[0067]

[0068] Under argon protection, compound 5 (0.14 mmol) and compound BODPP (601 mg, 0.84 mmol) (purchased from Nanjing Zhiyan Technology Co., Ltd.) were added to a 100 mL double-necked round-bottom flask, dissolved with 20 mL THF and 10 ml Et3N ultra-dry solvent, and then tetrakis(triphenylphosphine)palladium (24.3 mg, 0.021 mmol) and cuprous iodide (4 mg, 0.021 mmol) were added. After the reaction system was ventilated three times, it was reacted at 65 ° C in the dark for 72 hours. After the reaction was completed, it was spin-dried and eluted with petroleum ether and dichloromethane. Silica gel chromatography column was used, GPC column chromatography was performed using THF as eluent, and then recrystallized from chloroform and methanol to obtain the final product BODPP-Por (301 mg, 65% yield). 1H NMR (500 MHz, CDCl3) δ 8.92-8.87 (m, 8H), 8.59 (s, 4H), 8.12 (d, J = 6.9 Hz, 8H), 7.79 (t, J = 7.6 Hz, 4H), 7.71 (t, J = 7.5 Hz, 8H), 7.61 (dd, J = 5.0, 0.9 Hz, 4H), 7.28 (d, J = 4.7 Hz, 4H), 7.24 (d, J = 4.9 Hz, 4H), 4.02 (t, J = 6.6 Hz, 16H), 1.94 (m, J = 24.0 Hz, 8H), 1.32-1.17 (m, 128H), 0.85-0.74 (m, 48H), H NMR spectrum see Figure 3 .

[0069] Matrix-assisted laser desorption ionization time-of-flight mass spectrometry: experimental value 3314.4; calculated value C 204 H 244 N 12 O8S8Zn3314.13, see Figure 4 .

[0070] The donor photovoltaic material prepared in this example was dissolved in chloroform solution, and its mass concentration was (10 -5 -10 - 4 mol / L), the UV-visible absorption spectrum of the obtained chloroform solution is shown in Figure 6 .

[0071] The donor photovoltaic material prepared in this example was prepared into a thin film by spin coating, with a film thickness of about 70 nm. The ultraviolet-visible absorption spectrum of the thin film is shown in FIG. Figure 6 .

[0072] Using the porphyrin molecules of this example as donor materials and the small molecule Y6 as acceptor materials, a positive device was prepared to study photovoltaic performance. The structure of the device is ITO / PEDOT:PSS / active layer / PFN-Br / Ag, and the mass ratio of the active layer to the acceptor is 1:0.9. The JV curve under illumination is shown in Figure 2. Figure 7 The device has a photoelectric conversion efficiency of 6.21% and a short-circuit current of 16.72 mA / cm 2 , the open circuit voltage is 0.79V and the fill factor is 47.01%.

[0073] The photoelectric conversion efficiency achieved by the heterojunction cell prepared in this embodiment is the highest photoelectric conversion efficiency achieved by optimizing the donor-acceptor ratio, using an active layer material prepared with a donor-acceptor mass ratio of 1:0.9, and performing thermal annealing.

[0074] By preparing the small molecule donors in Example 1 and Example 2, respectively, it can be seen that the two donor photovoltaic materials have similar absorption. In solution, the absorption peaks of the Soret band and the Q band are located at around 480nm and 700nm, respectively, indicating that there is intramolecular charge transfer between the porphyrin core and the DPP end group, and the absorption peak of around 570nm is attributed to the absorption of the DPP unit; in the thin film state, the absorption of the Soret band and the Q band becomes stronger, the absorption has a red shift of about 20nm, and the absorption peak is broadened, which is attributed to the enhancement of molecular stacking in the solid state. The absorption edge of the molecule EHDPP-Por in Example 1 is 796nm, and the absorption edge of the molecule BODPP-Por in Example 2 is 789nm.

[0075] By comparing the efficiency of the heterojunction batteries prepared in Example 1 and Example 2 with Y6, it can be seen that the molecule BODPP-Por has higher open circuit voltage, short circuit current and fill factor than EHDPP-Por, and therefore has a higher PCE value, extends the alkyl side chain, and optimizes the performance of the material.

[0076] The synthesis methods of other small molecule photovoltaic materials based on the four β-position substitutions of porphyrin to connect the energy-absorbing units are similar to the above method and will not be repeated here.

[0077] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A class of β-tetrasubstituted porphyrin organic photovoltaic materials, characterized in that: It has the following chemical structure: Wherein, R is hydrogen; The specific structure of A is at least one of the following:

2. The method for preparing a β-tetrasubstituted porphyrin organic photovoltaic material according to claim 1, characterized in that: The following steps are involved: (1) Dissolve compound I in an organic solvent and react with N-bromosuccinimide at 60-70°C for 3-5 hours to obtain a compound represented by formula II; (2) dissolving compound II in an organic solvent, adding zinc acetate and reacting at 60-70° C. for 8-15 hours to obtain compound III; (3) dissolving compound III in an organic solvent, adding triisopropylsilyl acetylene, and reacting at 60-70° C. for 18-30 hours in the presence of a catalyst to obtain intermediate product IV; (4) Dissolve the intermediate product IV in an organic solvent, add tetrabutylammonium fluoride solution at room temperature, stir and react for 5-30 minutes, terminate the reaction, extract, spin dry and directly use in the next reaction; (5) heating and refluxing the spin-dried product in step (4) and the diketopyrrolidine monomer of the acceptor molecule A in an organic solvent under the action of a catalyst for 48-72 hours to obtain the β-tetrasubstituted porphyrin organic photovoltaic material; The definitions of R and A are consistent with those in claim 1; The catalyst in step (3) is bis(triphenylphosphine)palladium dichloride and cuprous iodide; The catalyst in step (5) is tetrakis(triphenylphosphine)palladium and cuprous iodide.

3. The method for preparing a β-tetrasubstituted porphyrin organic photovoltaic material according to claim 2, characterized in that: The organic solvent in step (1) is at least one of chloroform and dichloromethane; The molar ratio of compound I to N-bromosuccinimide in step (1) is 1:5-1:

7.

4. The method for preparing a β-tetrasubstituted porphyrin organic photovoltaic material according to claim 2, wherein: The organic solvent in step (2) is a mixed solution of chloroform and methanol; the molar amount of chloroform is 3000-4000 times the molar amount of compound (II), and the volume ratio of chloroform to methanol is 6:1-3:1; The molar ratio of compound (II) to zinc acetate in step (2) is 1:5-1:

8.

5. The method for preparing a β-tetrasubstituted porphyrin organic photovoltaic material according to claim 2, characterized in that: The organic solvent in step (3) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 1000-3000 times the molar amount of compound (III), and the volume ratio of tetrahydrofuran to triethylamine is 2:1-5:1; The molar ratio of compound III to triisopropylsilyl acetylene in step (3) is 1:8-1:12; The molar amounts of the catalysts bis(triphenylphosphine)palladium dichloride and cuprous iodide in step (3) are both 0.15 times the molar amount of compound (III).

6. The method for preparing a β-tetrasubstituted porphyrin organic photovoltaic material according to claim 2, characterized in that: The organic solvent in step (4) is tetrahydrofuran; the molar amount of tetrahydrofuran is 1000-3000 times the molar amount of intermediate product IV; The molar ratio of the intermediate product IV to tetrabutylammonium fluoride in step (4) is 1:6-1:

8.

7. The method for preparing a β-tetrasubstituted porphyrin organic photovoltaic material according to claim 2, characterized in that: The molar ratio of the spin-dried product in step (5) to the diketopyrrolidine monomer of the receptor molecule A is 1:6-1:8; The organic solvent in step (5) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 1000-3000 times the molar amount of the spin-dried product, and the volume ratio of tetrahydrofuran to triethylamine is 2:1-5:1; The molar amounts of the catalyst tetrakis(triphenylphosphine)palladium and cuprous iodide in step (5) are both 0.15 times the molar amount of the spin-dried product.

8. Use of the β-tetrasubstituted porphyrin organic photovoltaic material according to claim 1 in an organic solar cell.

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