Indenothiophene-based dimer solar cell donor material and application thereof

Abstract

The application relates to application of an indenothiophene-based dimer donor material in an organic solar cell and belongs to the technical field of organic functional materials and photovoltaic cells. The application discloses an indenothiophene-based dimer donor material (formula 1), which is doped into a PM6:Y6 system as a third component of an active layer donor material to prepare a ternary organic solar cell, and the energy conversion efficiency (PCE) of the device is 17.06%. Moreover, the preparation and synthesis method of the indenothiophene-based dimer donor material is simple, green, non-toxic, high in yield, excellent in batch performance consistency, and easy to adjust the structure, and the like. This shows that the dimer donor material is an effective way to improve the photovoltaic performance and stability of the photovoltaic device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic solar cell donor materials and organic solar cell devices: 1. It relates to the preparation of an indenothiophene-based dimer solar cell donor material; 2. With the material as the third component of the organic solar cell, it is doped in the PM6:Y6 system, and an organic photovoltaic cell device is prepared, and an effective method for improving the stability and PCE of the device is obtained. BACKGROUND

[0002] Organic solar cells are considered to be a new energy technology with great application prospects due to their light weight, flexibility and the ability to prepare large-area devices. At present, the highest efficiency of single active layer binary organic solar cell device has reached 19.70%. However, due to the narrow absorption spectrum of organic semiconductor materials, it is difficult to effectively utilize solar energy. In ternary organic solar cells (TOSCs), three different components are mixed together to form a photoactive layer, which provides an opportunity to improve the power conversion efficiency, such as by broadening the absorption range, improving the mixed morphology or adjusting the exciton splitting and charge extraction. Due to these possibilities, ternary systems are among the best performing OSCs and will play a crucial role in the future of organic photovoltaics. At present, the third component of TOSCs has been reported to be mainly an acceptor material, and there are few literature reports on donor materials as the third component. Among them, oligomeric donor materials have both the advantages of small molecules and polymers, and have been widely concerned in the development of organic solar cells due to their excellent photoelectric performance, charge transport performance, good stability and easy-to-control energy level. SUMMARY

[0003] In view of the current research status of organic solar cell donor materials, the purpose of the present application is to design a kind of indenothiophene-based dimer solar cell donor material, and to prepare a bulk heterojunction organic solar cell device to realize a new method for improving the energy conversion efficiency (PCE).

[0004] The technical scheme of the present application is as follows:

[0005] A kind of indenothiophene-based dimer solar cell donor material, wherein the molecular structure formula of the dimer is:

[0006] Wherein R is C6-C 12 One of the straight-chain alkyl groups.

[0007] A preparation method of an indenothiophene-based dimer solar cell donor material, wherein the preparation of the molecular structure formula of the dimer comprises the following steps:

[0008] (1) the chemical structure formula is and 3-ethylrhodanine were added to a double-port reaction flask of a magnetic stirrer; the double-port reaction flask was vacuumized and N2 was introduced, and piperidine was added to the reaction flask to obtain a second reaction mixture;

[0009] (2) the second reaction mixture was heated to a second predetermined temperature and stirred at the second predetermined temperature for a second predetermined time to obtain a second mixed product; the second mixed product was subjected to a purification treatment to prepare the dimer structure general formula.

[0010] The indenothiophene dimer donor material was doped as a third component in the PM6:Y6 system, and a PM6: indenothiophene dimer donor material:Y6 ternary device was prepared; the mass ratio of PM6:Y6:indenothiophene dimer donor material was 1:1.2:0.05-0.2; and the optimal mass ratio was 1:1.2:0.1.

[0011] The application also provides an application of the indenothiophene dimer solar cell donor material, and the device structure is: ITO / PEDOT:PSS (30 nm) / PM6:dimer donor material:Y6 (100 nm) / PDINO (5 nm) / Ag (100 nm). The active layer is based on PM6: indenothiophene dimer donor material:Y6.

[0012] Compared with the prior art, the dimer donor material provided by the application has the advantages that the synthesis method is simple, green and environmentally friendly, and the yield is high; the synthesized material has good stability and solubility; after being prepared into a heterojunction device, the photovoltaic characteristics of the dimer are improved compared with the photovoltaic characteristics of a haploid. This shows that the dimer donor is an effective way to improve the photovoltaic performance and stability of a photovoltaic device. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The figure is an organic solar cell device structure of the application;

[0014] Figure 2 The figure is a synthesis route of C6dIOEH-RDN32 and C12dIOEH-RDN32 in the application;

[0015] Figure 3 The figure is a nuclear magnetic hydrogen spectrum of intermediate 2 in Example 1 of the application;

[0016] Figure 4 The figure is a nuclear magnetic hydrogen spectrum of C6dIOEH-RDN32 in Example 1 of the application;

[0017] Figure 5 The figure is a nuclear magnetic hydrogen spectrum of intermediate 2 in Example 2 of the application;

[0018] Figure 6NMR of Example 2C12d10EH-RDN32 of the present application;

[0019] Figure 7 UV absorption spectra of solution and solid film of Example 1C6d10EH-RDN32 of the present application;

[0020] Figure 8 UV absorption spectra of solution and solid film of Example 2C12d10EH-RDN32 of the present application;

[0021] Figure 9 UV absorption spectra of solution and solid film of Comparative Example 1 IOEH-RDN32 of the present application;

[0022] Figure 10 Cyclic voltammogram of Example 1C6d10EH-RDN32 of the present application;

[0023] Figure 11 Current-voltage (J-V) curve of the organic solar cell device of Example 1 of the present application;

[0024] Figure 12 Current-voltage (J-V) curve of the organic solar cell device of Comparative Example 1 of the present application.

[0025] Figure 13 Current-voltage (J-V) curve of the organic solar cell device of Example 2 of the present application; DETAILED DESCRIPTION

[0026] The following specific examples are intended to further illustrate the present application, but these specific examples are not intended to limit the scope of the present application in any way.

[0027] Example 1

[0028] 1. Synthesis of C6d10EH-RDN32:

[0029]

[0030] Compound 1 (180 mg, 0.18 mmol), 4,4-bis(2-ethylhexyl)-4H cyclopenta[2,1- b:3,4-b']dithiophene-2,6-dicarboxaldehyde (DTC-CHO) (232 mg, 0.54 mmol) were dissolved in dry toluene (35 mL), added CS2CO3 (234 mg, 0.72 mmol), pivalic acid (PiVOH) (18 mg, 0.18 mmol), Pd2(dba)3 (33 mg, 0.036 mg), tris(2-methoxyphenyl)phosphine (P(O-CH3OPh)3) (51 mg, 0.14 mmol), and reacted overnight at 110 °C under nitrogen atmosphere. After the reaction was completed, the filtrate was filtered through a suction filter funnel, the filtrate was collected, the solvent was removed by a rotary evaporator, and column chromatography on silica gel (eluent: pure dichloromethane) was performed to purify, to obtain compound 2 (125 mg, 44%) as an orange-yellow oily substance. 1 H NMR (400 MHz, Chloroform-d) δ 9.90 (s, 2H), 9.83 (s, 2H), 7.63 (s, 2H), 7.59 (s, 4H), 7.52 (t, J = 5.1 Hz, 2H), 7.16 (s, 2H), 4.28 (t, J = 6.1 Hz, 4H), 2.13 (t, J = 6.6 Hz, 4H), 1.99 (dq, J = 15.4, 4.8, 4.4 Hz, 11H), 1.89 (td, J = 14.0, 13.3, 5.7 Hz, 5H), 1.80 (d, J = 6.6 Hz, 4H), 1.36 - 1.22 (m, 6H), 1.19 - 1.04 (m, 27H), 0.99 - 0.94 (m, 15H), 0.94 - 0.90 (m, 9H), 0.87 - 0.82 (m, 6H), 0.78 (t, J = 6.9 Hz, 11H), 0.73 (t, J = 6.7 Hz, 7H), 0.68 - 0.59 (m, 21H).

[0031] Compound 2 (190 mg, 0.11 mmol) and 3-ethylrhodanine (90 mg, 0.56 mmol) were dissolved in chloroform (20 mL), then piperidine (1.5 mL) was added, and reacted at 60 °C under nitrogen atmosphere for 12 h. After the reaction was completed, the reaction solution was slowly dropped into 100 mL of methanol to precipitate, and the crude product was filtered with a mobile phase to purify by column chromatography on silica gel (eluent: petroleum ether:dichloromethane = 1:1), to obtain C6dIOEH-RDN32 (140 mg, 70%) as a blue-purple solid. 1HNMR (400 MHz, Chloroform-d) δ 7.92 (s, 2H), 7.86 (s, 2H), 7.61 (d, J = 2.5 Hz, 2H), 7.52 (tt, J = 5.1, 2.5 Hz, 2H), 7.27 (s, 2H), 7.23 (d, J = 2.5 Hz, 2H), 7.15 (s, 2H), 4.39 - 4.27 (m, 4H), 4.19 (t, J = 7.4 Hz, 8H), 2.17 (t, J = 7.0 Hz, 4H), 2.06 - 1.79 (m, 20H), 1.58 (s, 4H), 1.29 (q, J = 7.4 Hz, 12H), 1.20 - 1.05 (m, 24H), 1.04 - 0.89 (m, 31 H), 0.84 (d, J = 8.6 Hz, 5H), 0.78 (t, J = 6.9 Hz, 14H), 0.72 (t, J = 6.7 Hz, 6H), 0.69 - 0.64 (m, 10H), 0.64 - 0.62 (m, 4H), 0.60 (d, J = 7.5 Hz, 6H).

[0032] 2. The device structure of the organic solar cell based on Example 1 is: ITO / PEDOT:PSS / active layer / PDINO / Ag. Wherein the mass ratio of the active layer PM6:Y6:C6dIOEH-RDN32 is 1:1.2:0.1. The production scheme is as follows:

[0033] Cleaning and pretreatment of ITO substrate

[0034] The ITO substrate was sequentially cleaned in an ultrasonic cleaning instrument according to the order of washing solution (10 min), isopropanol (20 min), acetone (20 min), deionized water (10 min x 4), isopropanol (20 min), and dried in an oven overnight. Before use, the ITO surface was subjected to 15 min ultraviolet ozone surface treatment and cooled to room temperature.

[0035] Spin coating of hole transport layer PEDOT:PSS

[0036] The PEDOT:PSS solution was spin-coated at room temperature in air environment at a speed of 2500 r / min for 30 s, then baked at 100°C for 15 min, and then cooled at room temperature for 15 min to prepare a uniform and smooth film.

[0037] Mixing and spin coating of active layer material

[0038] The PM6:Y6:C6dIOEH-RDN32 with a mass ratio of 1:1.2:0.1 and a concentration of 10 mg / mL was dissolved in chloroform, and spin-coated at a speed of 2500 r / min for 30 s in a glove box under a nitrogen atmosphere. Then, the spin-coated device was annealed at different temperatures for 10 min, and then cooled at room temperature for 20 min to form a uniform and smooth film.

[0039] Spin-coating of the electron transport layer PDINO and evaporation of the cathode Ag

[0040] The PDINO with a concentration of 1 mg / mL was spin-coated at a speed of 3000 r / min for 30 s in a glove box under a nitrogen atmosphere to form a uniform and smooth film. Then, the spin-coated device was placed in a vacuum evaporation chamber and 100 nm of metal electrode Ag was evaporated on the active layer at a pressure of 1×10 -5

[0041] Performance test of the device

[0042] Under standard test conditions (AM1.5, 100 mW / cm 2 ), the V oc of the device was 0.871 V, the J sc was 25.43 mA / cm 2 , the FF was 76.90%, and the PCE was 17.05%.

[0043] Table 1. Device performance parameters based on PM6:Y6:C6dIOEH-RDN32 under different ratios

[0044]

[0045] Comparative Example 1

[0046] 1. Synthesis of haploid IOEH-RDN32

[0047]

[0048] Compound 1 (100 mg, 0.11 mmol) and 3-ethyl rhodanine (52 mg, 0.32 mmol) were dissolved in chloroform (20 mL), and then piperidine (1.5 mL) was added. The reaction was carried out at 60°C under a nitrogen atmosphere for 12 h. After the reaction was completed, the reaction solution was slowly dropped into 100 mL of methanol for precipitation, and the crude product was filtered with a mobile phase. Purification was performed by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 1:1) to obtain a blue-purple solid (92 mg, 70%). 1 ​HNMR (400 MHz, CDC13) δ 7.84 (s, 1H), 7.81 (d, J = 2.6 Hz, 1H), 7.46 (s, 1H), 7.43 (d, J = 4.3 Hz, 1H), 7.18 (d, J = 4.3 Hz, 1H), 7.15 (d, J = 2.6 Hz, 1H), 7.03 (s, 1H), 4.12 (q, J = 7.1 Hz, 4H), 4.02 (d, J = 5.6 Hz, 2H), 0.69 (t, J = 6.9 Hz, 6H), 2.00 - 0.40 (m, 75H).

[0049] 2. The device structure of the solar cell based on Comparative Example 1 is: ITO / PEDOT:PSS / IOEH-RDN32:Y6 / PDINO / Ag. The mass ratio of the active layer PM6:Y6:IOEH-RDN32 is 1:1.2:0.1. The production scheme is as follows:

[0050] Cleaning and pretreatment of ITO substrate

[0051] The ITO substrate was sequentially cleaned in an ultrasonic cleaning instrument according to the order of washing liquid (10 min), isopropanol (20 min), acetone (20 min), deionized water (10 min x 4), isopropanol (20 min), and dried in an oven overnight. Before use, the ITO surface was subjected to 15 min ultraviolet ozone surface treatment and cooled to room temperature.

[0052] Spin coating of hole transport layer PEDOT:PSS

[0053] The PEDOT:PSS solution was spin-coated at room temperature in air environment at a speed of 2500 r / min for 30 s, then baked at 100°C for 15 min, and then cooled at room temperature for 15 min to prepare a uniform and smooth film.

[0054] Mixing and spin coating of active layer material

[0055] In a nitrogen atmosphere glove box, PM6:Y6:IOEH-RDN32 was dissolved in chloroform at a mass ratio of 1:1.2:0.1 and a donor concentration of 10 mg / mL, and spin-coated at a speed of 2500 r / min for 30 s, then annealed at 100°C for 10 min, and then cooled at room temperature for 20 min to prepare a uniform and smooth film.

[0056] Spin coating of electron transport layer PDINO and evaporation of cathode Ag

[0057] PDINO was spin-coated at a concentration of 1 mg / mL at a speed of 3000 r / min for 30 s to form a uniform and smooth thin film in a glove box under nitrogen atmosphere, and then the spin-coated device was placed in a vacuum evaporation chamber to evaporate 100 nm of metal electrode Ag on the active layer at 1×10 -5 Pa.

[0058] Performance test of the device

[0059] Under standard test conditions (AM1.5, 100 mW / cm 2 ), the V oc = 0.868 V, J sc = 25.59 mA / cm 2 , FF = 75.99%, and PCE = 16.89% were measured for the device.

[0060] The absorption spectra of C6dIOEH-RDN32 and IOEH-RDN32 in chloroform solution and in thin film state were tested using a UV-visible spectrophotometer. C6dIOEH-RDN32 showed strong absorption in the range of 440-650 nm in a dilute chloroform solution, with a maximum absorption at 552 nm; IOEH-RDN32 showed strong absorption in the range of 450-642 nm, with a maximum absorption at 570 nm. The dimer has a wider absorption spectral range than the haploid; in a pure film state, the absorption curves of C6dIOEH-RDN32 and IOEH-RDN32 have a significant red shift compared to their respective solutions. The dimer absorption has a blue shift relative to the haploid, because the flexible linker links the two small molecules together, reducing the diffusion rate of the molecule.

[0061] Electrochemical test was performed on C6dIOEH-RDN32 prepared according to the present application. C6dIOEH-RDN32 was dissolved in chloroform to form a solution with a concentration of 1 mg / mL, and was dropped on the working electrode (dropping diameter of 2 mm). A 0.1M Bu4NPF6 acetonitrile solution was used as the electrolyte, a platinum wire was used as the counter electrode, Ag / Ag+ was used as the reference electrode, and ferrocene was used as the standard substance. Electrochemical cyclic voltammetry was used to measure the redox potential, and then the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were calculated.

[0062]

[0063] E g = 1240 / λ = 1240 / 800 = 1.55

[0064] LUMO = HOMO + E g = -5.41 + 1.55 = -3.86 eV

[0065] Example 2

[0066] 1. Synthesis of C12dIOEH-RDN32:

[0067]

[0068] Compound 1 (362 mg, 0.41 mmol), DTC-CHO (535 mg, 1.24 mmol) were dissolved in dry toluene (80 mL), then CS2CO3 (539 mg, 1.66 mmol), PiVOH (42 mg, 0.41 mmol), Pd2(dba)3 (76 mg, 0.083 mg), P(O-CH3OPh)3 (117 mg, 0.33 mmol) were added, and the reaction was carried out at 110 °C under nitrogen atmosphere overnight. After the reaction was completed, the filtrate was filtered through a suction filter funnel, the filtrate was collected, the solvent was removed by a rotary evaporator, and the product was purified by silica gel column chromatography (eluent: pure dichloromethane) to obtain compound 2 (125 mg, 44%) as an orange-yellow oily substance. 1 H NMR (400 MHz, Chloroform-d) δ 9.90 (s, 2H), 9.83 (s, 2H), 7.63 (s, 2H), 7.57 (d, J = 5.8 Hz, 4H), 7.52 (d, J = 4.4 Hz, 2H), 7.15 (s, 2H), 4.22 (t, J = 6.6 Hz, 4H), 2.08 - 1.93 (m, 16H), 1.89 (t, J = 11.1 Hz, 5H), 1.61 (p, J = 7.3 Hz, 4H), 1.49 - 1.32 (m, 13H), 1.19 - 1.07 (m, 25H), 1.02 - 0.89 (m, 30H), 0.79 (td, J = 17.1, 14.9, 6.0 Hz, 27H), 0.64 (dt, J = 14.7, 6.9 Hz, 20H).

[0069] Compound 2 (202 mg, 0.11 mmol) and 3-ethylrhodanine (91 mg, 0.56 mmol) were dissolved in chloroform (20 mL), then piperidine (1.5 mL) was added, and the reaction was carried out at 60 °C under nitrogen atmosphere for 12 h. After the reaction was completed, the reaction solution was slowly dropped into 100 mL of methanol to precipitate, and the crude product was filtered with a mobile phase to obtain a blue-purple solid C12dIOEH-RDN32 (186 mg, 70%) after purification by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 1:1). 1H NMR (400 MHz, Chloroform-d) δ 7.94 (s, 2H), 7.92 (d, J = 2.4 Hz, 2H), 7.58 (s, 2H), 7.53 (d, J = 4.4 Hz, 2H), 7.28 (d, J = 3.0 Hz, 3H), 7.25 (s, 1H), 7.13 (s, 2H), 4.33 - 4.11 (m, 12H), 2.00 (ddt, J = 31.7, 26.3, 7.2 Hz, 20H), 1.64 (dt, J = 12.0, 5.6 Hz, 5H), 1.55 - 1.41 (m, 12H), 1.31 (td, J = 7.2, 3.7 Hz, 13H), 1.16 (dt, J = 18.0, 5.8 Hz, 23H), 1.05 - 0.91 (m, 31H), 0.88 - 0.73 (m, 27H), 0.66 (dt, J = 19.6, 6.6 Hz, 21H).

[0070] 2. The device structure of the organic solar cell based on Example 2 is: ITO / PEDOT:PSS / active layer / PDINO / Ag. The mass ratio of the active layer PM6:Y6:C12dIOEH-RDN32 is 1:1.2:0.1. The production scheme is as follows:

[0071] Cleaning and pretreatment of ITO substrate

[0072] The ITO substrate is sequentially cleaned in an ultrasonic cleaning instrument according to the order of washing liquid (10 min), isopropanol (20 min), acetone (20 min), deionized water (10 min x 4), isopropanol (20 min), and dried in an oven overnight. Before use, the ITO surface is subjected to 15 min ultraviolet ozone surface treatment and cooled to room temperature.

[0073] Spin coating of hole transport layer PEDOT:PSS

[0074] The PEDOT:PSS solution is spin-coated at room temperature in an air environment at a speed of 2500 r / min for 30 s, then baked at 100°C for 15 min, and then cooled at room temperature for 15 min to prepare a uniform and smooth film.

[0075] Mixing and spin coating of active layer material

[0076] In a nitrogen atmosphere glove box, PM6:Y6:C12dIOEH-RDN32 with a mass ratio of 1:1.2:0.1 and a donor concentration of 10 mg / mL is dissolved in chloroform and spin-coated at a speed of 2500 r / min for 30 s, then annealed at different temperatures for 10 min, and then cooled at room temperature for 20 min to prepare a uniform and smooth film.

[0077] Spin-coating of electron transport layer PDINO, evaporation of cathode Ag

[0078] PDINO with a concentration of 1 mg / mL was spin-coated at a speed of 3000 r / min for 30 s to form a uniform and smooth thin film in a nitrogen atmosphere glove box, and then the spin-coated device was placed in a vacuum evaporation chamber to evaporate 100 nm of metal electrode Ag on the active layer at 1 × 10 -5

[0079] Performance test of the device

[0080] Under standard test conditions (AM1.5, 100 mW / cm 2 ), the V oc of the device was measured to be 0.871 V, the J sc was 25.91 mA / cm 2 , the FF was 75.57%, and the PCE was 17.06%.

[0081] The absorption spectrum of C12dIOEH-RDN32 in chloroform solution and in thin film state was tested using a UV-visible spectrophotometer. C12dIOEH-RDN32 showed strong absorption in the 437-658 nm region in a dilute chloroform solution, with a maximum absorption at 550 nm. In the pure film state, the absorption curves of C12dIOEH-RDN32 and IOEH-RDN32 showed a significant red shift compared to the solution.

[0082] Table 2, device performance parameters based on PM6:Y6:C12dIOEH-RDN32 under different proportions

[0083]

[0084] Table 3, device performance parameters based on PM6:Y6 under different third components and optimal proportions

[0085]

[0086] Although the present application has been described in conjunction with the preferred embodiments, it is to be understood that modifications and variations can be resorted to without departing from the spirit and scope of the application, as broadly disclosed herein and in the appended claims. It is to be understood that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.​

Claims

1. An indenothiophene-based dimer solar cell donor material, characterized by, The chemical structure of the donor material is as follows: wherein R is C6-C 12 one of the linear alkyl groups.

2. The indaceno-thienoacene dimer-based solar cell donor material according to claim 1, characterized in that, The dimer donor is one of C6dIOEH-RDN32 and C12dIOEH-RDN32; The chemical structural formula of C6dIOEH-RDN32 is as follows: The chemical structural formula of C12dIOEH-RDN32 is as follows:

3. Use of an indenothiophene-based dimer solar cell donor material according to claim 1 or 2, characterized in that: The application of the indenothiophene dimer as a donor material in a solar cell device.

4. Use of an indaceno-thiophene-based dimer solar cell donor material according to claim 3, characterized in that: The indenothiophene dimer donor material is doped as a third component in a PM6:Y6 system to prepare a ternary device of PM6: indenothiophene dimer donor material: Y6.

5. Use of an indaceno-thiophene-based dimer solar cell donor material according to claim 4, characterized in that: The mass ratio of PM6: indenothiophene dimer donor material: Y6 is 1:0.05-0.2:1.

2.

6. Use of an indaceno-thiophene-based dimer solar cell donor material according to claim 5, characterized in that: The mass ratio of PM6: indenothiophene dimer donor material: Y6 is 1:0.1:1.

2.

7. Use of an indaceno-thiophene-based dimer solar cell donor material according to claim 4, characterized in that: The device structure is as follows: ITO / PEDOT:PSS / PM6: dimer donor material: Y6 / PDINO / Ag.

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