A kind of double-BODIPY-based organic solar cell small molecule donor material and its preparation method and application

Abstract

The application relates to preparation and application of a kind of double-BODIPY-based organic solar cell small molecule donor material, the small molecule donor material ZMH-3 and ZMH-4 are introduced by introducing electron-withdrawing group five fluorophenyl in meso position, and using Knoevenagel condensation reaction to introduce electron-donating group carbazole or triphenylamine (TPA) group in 3,5 position.The two kinds of small molecule donor materials have narrow band gap, good solubility and large stokes shift.The small molecule donor material provided by the application has suitable energy level and spectral absorption, can form good absorption complement and energy level matching with non-fullerene small molecule fused ring electron acceptor material ITIC;The small molecule donor material is used as the electron donor material of active layer to prepare an organic solar cell, under the optimization condition, the active layer is ZMH-3:ITIC and ZMH-4:ITIC, and the cell obtains photoelectric conversion efficiency of 12.26 and 8.23% respectively, which has potential practical application value and prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of organic compound synthesis, organic solar energy and fine chemical technology, and particularly relates to preparation and application of a BODIPY-based solar cell small molecule donor material. BACKGROUND

[0002] The exhaustion of fossil energy and the severe domestic and international situation make the energy crisis more and more serious, and the overexploitation and use of traditional fossil energy also cause serious environmental and social problems, so it is more and more important to develop clean energy. Among them, the organic solar cell (OSCs) based on the heterojunction (BHJ) active layer (a mixture of organic semiconductor donor and acceptor materials) has attracted the attention of many researchers due to its potential advantages. First, the types and sources of OSCs materials are very extensive, and do not contain any rare elements; second, the structure of such materials is very adjustable, and the functional molecules with target band gap and absorption range can be obtained by optimizing and adjusting the structure, for example, the compounds concentrated in the visible light absorption region can be applied to the indoor soft light field; third, OSCs can be processed by solution method, and can be mass-produced by roll-to-roll printing technology, which is low in cost and is conducive to large-scale commercialization; finally, due to its pollution-free, noiseless, low-cost, light-weight, and flexible device preparation characteristics, it has great application prospects in the future flexible wearable devices, therefore, more and more researchers are engaged in research in this field.

[0003] The core part of the organic solar cell is an organic semiconductor material with photosensitive properties. Organic matter has the characteristics of light weight, simple preparation, semi-transparency, and flexible device, and shows great development potential in the photovoltaic field. However, due to the difficulty in controlling polymers, the repeatability is poor, which is not only not conducive to the analysis of the structure, but also the different polymerization degrees will affect the performance of the device, thereby leading to the difference in the performance of the solar cell with the change of the polymerization degree of the polymer. Compared with polymer materials, small molecule organic materials have the advantages of solubility, simple synthesis and purification, easy modification of molecular structure, and no batch variation. However, the small area power conversion efficiency (PCE) of small molecule solar cells (SMDs) is far behind that of polymers as donors. At present, it is still a great challenge to design and synthesize small molecule donors with high PCE. Therefore, it is of great scientific significance to reasonably design and optimize the molecular configuration and construct efficient small molecule donors matched with these excellent acceptors.

[0004] As an important class of multifunctional fluorophores, boron-dipyrromethene (BODIPY) dyes have many excellent optical properties, such as relatively high molar extinction coefficient and fluorescence quantum yield, good photochemical and thermal stability, and low optical band gap. In addition, BODIPY derivatives are easy to synthesize, and by proper synthetic modification of the BODIPY core, the introduction of appropriate electron donors and electron acceptors can reasonably adjust their optical and electrochemical properties. Therefore, the superior optical and electrochemical properties and the superior modifiability of BODIPY make it have wide application prospects in the field of organic solar cells.

[0005] The present application relates to the preparation and application of an organic solar cell small molecule donor material, using meso strong electron-withdrawing pentafluorophenyl BODIPY derivatives connected by covalent bond, respectively introducing triphenylamine (TPA) or carbazole (CZ) group as electron donor at 3 and 5 positions of BODIPY parent body, effectively adjusting the molecular spectral absorption, energy level distribution and molecular crystallinity by molecular structure modification, and then improving the device performance, providing a new idea for designing and synthesizing new SMDs. The small molecule donors ZMH-3 and ZMH-4 and the non-fullerene electron acceptor ITIC are used as active layer materials in organic solar cells, and good results are obtained, and the photoelectric conversion efficiency can be up to 12.26%, which has good application prospect in the field of organic solar cells. SUMMARY

[0006] The purpose of the present application is to overcome the deficiencies in the prior art, and the purpose of the present application is to prepare a kind of double BODIPY base organic solar cell small molecule donor material and its application.

[0007] Technical scheme: in order to realize the above-mentioned purpose of the present application, the technical scheme adopted by the present application is:

[0008] The preparation and application of a kind of double BODIPY base organic solar cell small molecule donor material of the present application, characterized in that the compound has the structure shown in formula ZMH-3 and ZMH-4:

[0009]

[0010] The preparation method of the organic solar cell small molecule donor material of the present application is as follows:

[0011] 1) under the protection of nitrogen, BODIPY monomer derivative (I) is dissolved in dry dichloromethane, and the solution of ferric chloride in nitromethane is added dropwise at-78℃, after the addition is completed, the reaction is carried out for half an hour, and then the reaction mixture is diluted with dichloromethane, washed with water, and the organic layer is dried with anhydrous sodium sulfate, and then the solvent is removed by vacuum distillation and separated and purified by silica gel column chromatography, and the eluent is dichloromethane-petroleum ether (v:v = 1:1), to obtain compound (II);

[0012] 2) Under the condition of no water, compound (II) is respectively put into a 100mL double-neck reaction bottle with 4-(N,N-diphenylamino)benzaldehyde and 9-butyl-9H-carbazole-3-carboxaldehyde, then new dry p-toluenesulfonic acid is added, followed by 10mL anhydrous toluene dissolved, and 0.2mL piperidine is added as a catalyst, heated to reflux for 4-6 hours, after the reaction is completed, it is cooled to room temperature, the mixture is diluted with dichloromethane, washed with water, the organic layer is dried over anhydrous sodium sulfate, after removing the solvent by reduced pressure distillation, it is separated and purified by silica gel column chromatography, the eluent is dichloromethane-petroleum ether (v:v = 1:1), to obtain small molecule donor materials ZMH-3 and ZMH-4, the specific chemical reaction formula is shown as follows:

[0013]

[0014] In the above step 1), the molar ratio of BODIPY monomer derivative (I) to ferric chloride is 1:3;

[0015] In the above step 2), the molar ratio of compound (II), p-toluenesulfonic acid and 4-(N,N-diphenylamino)benzaldehyde is 1:1:5.0, the molar ratio of compound (II), p-toluenesulfonic acid and 9-butyl-9H-carbazole-3-carboxaldehyde is 1:1:5.0, the volume and molar ratio of toluene, piperidine and compound (I) is 50mL:1mL:1mmol;

[0016] The application of the small molecule donor in the organic solar cell includes the following steps:

[0017] (1) The ITO glass is ultrasonically cleaned with detergent, deionized water, acetone and isopropanol in sequence, and then vacuum dried;

[0018] (2) PEDOT:PSS is spin-coated on the ITO glass at a spin-coating speed of 2500rpm / min to prepare a 35-40nm-thick hole transport layer;

[0019] (3) ZMH-3:ITIC and ZMH-4:ITIC are dissolved in chloroform solvent at a certain mass ratio, and the concentration is 16mg / mL, and the electron donor and electron acceptor materials are spin-coated on the hole PEDOT:PSS transport layer at room temperature and in a nitrogen atmosphere, the spin-coating speed is 2500rpm / min, and the spin-coating time is 60s, to form a bulk heterojunction film, and then the film is treated by solvent vapor annealing, and exposed to tetrahydrofuran vapor for 40s for annealing;

[0020] (4) Dissolve PFN in methanol solvent, spin-coat on the top of the active layer, the spin-coating speed is 3000 rpm / min, and the spin-coating time is 1 min; form an electron transport layer;

[0021] (5) Under vacuum condition, deposit metal aluminum (Al) by thermal evaporation to the top of the PFN electron transport layer.

[0022] The organic solar cell provided by the application is a kind of organic solar cell, and the structure of the cell device is from bottom to top as follows: transparent conductive substrate (ITO glass), hole transport layer (poly (3, 4-ethylenedioxythiophene) (PEDOT): poly (styrene sulfonic acid) (PSS)), organic active layer, electron transport layer (polyfluorene derivative (PFN)), metal electrode (Al). The organic active layer is a bulk heterojunction ZMH-3: ITIC or ZMH-4: ITIC of a donor and an acceptor, respectively.

[0023] The molecular structural formula of the small molecule donor ZMH-3 and ZMH-4 and the non-fullerene fused ring electron acceptor material ITIC in the organic active layer of the application are as follows, respectively:

[0024]

[0025] Advantages of the application

[0026] Compared with the prior art, the application has the following advantages: (1) the reaction steps of the small molecule solar cell donor of the application are simple, the reaction conditions are mild, the selectivity is good, and the synthesis cost is low; (2) the two donor molecules ZMH-3 and ZMH-4 have long absorption wavelength, wide absorption range, narrow molecular energy level and high carrier performance, and the absorption spectrum is complementary to the acceptor material ITIC, which can widen the light absorption range of the whole system, thereby being conducive to improving the short-circuit current (Jsc) and photoelectric conversion performance of the device; (3) the small molecule organic solar cell device can be used as an electron donor material for preparing an organic small molecule organic solar cell device, and the photoelectric conversion efficiency can reach 12.26%, so that it has good application prospect in solar cells. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the electron absorption spectrum of the thin film of the donor material ZMH-3, ZMH-4 and the acceptor material ITIC, wherein the abscissa is wavelength (wavelength), unit: nm, and the ordinate is absorbance;

[0028] Figure 2The images show the thin film-fluorescence emission spectra of donor materials ZMH-3 and ZMH-4, and their respective blends with acceptor material ITIC. The horizontal axis represents wavelength (nm), and the vertical axis represents emission intensity.

[0029] Figure 3 The diagram shows the energy levels of the donor materials ZMH-3 and ZMH-4 and the acceptor material ITIC in the organic solar cells prepared in this invention. The vertical axis represents the energy level, and the unit is eV.

[0030] Figure 4 For the application of the small molecule donor of the present invention in organic solar cells, under preferred conditions, the device current (J) in the solar cell based on (a) ZMH-3:ITIC and (b) ZMH-4:ITIC is... sc - Voltage (V) oc )picture. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] use 1 The device was characterized and confirmed to possess a donor structure for a small-molecule solar cell by 1H-NMR and MALDI-TOF-MS spectroscopy. The instruments used for analysis were: a Bruker ARX400 NMR spectrometer and a Bruker ARX600 NMR spectrometer (both using deuterated chloroform as solvent); a Shimadzu UV-3100 UV-Vis spectrophotometer (scanning range 300-900 nm, optical path slit 2 nm); and fluorescence spectroscopy was measured using an Amico Bowman Series 2 Luminescence Spectrometer. The device's photoelectric conversion efficiency was measured using a Keithley 2400 source meter (AM1.5G, 100 mW / cm²). 2 )test.

[0033] Example 1

[0034] Preparation of compound (II)

[0035] Under nitrogen protection, monomeric BODIPY derivative (I) (134 mg, 0.4 mmol) was dissolved in dry dichloromethane (100 mL), and a nitromethane solution of ferric chloride (648 mg, 4 mmol) (4 mL) was added dropwise at -78 °C. After the addition was completed, the reaction was allowed to proceed for half an hour, and the mixture was allowed to rise naturally to room temperature. The mixture was diluted with dichloromethane and washed with water. The organic layer was dried over anhydrous sodium sulfate, the solvent was removed by vacuum distillation, and then purified by silica gel column chromatography with dichloromethane-petroleum ether (v1:v2 = 1:1) as the eluent to obtain compound (II) (86 mg, 56%).1 H NMR (400MHz, CDCl3): δ (ppm) 6.64 (d, J=4Hz, 2H), 6.48 (s, 2H), 6.35 (d, J=4.4Hz, 2H), 2.68 (s, 6H), 2.58 (s, 6H).

[0036] Example 2

[0037] Preparation of compound ZMH-3

[0038] Under anhydrous conditions, compound (II) (50 mg, 0.065 mmol) and 4-(N,N-diphenylamino)benzaldehyde (88 mg, 0.32 mmol) were placed in a 100 mL double-necked reaction flask. Freshly dried p-toluenesulfonic acid (11 mg, 0.065 mmol) was added, followed by the addition of anhydrous toluene (10 mL) to dissolve the compound. Piperidine (0.2 mL) was added as a catalyst, and the mixture was heated to reflux for 4–6 hours. After the reaction was completed, the mixture was cooled to room temperature, diluted with dichloromethane, washed with water, dried over anhydrous sodium sulfate, and purified by silica gel column chromatography after the solvent was evaporated under reduced pressure. The eluent was dichloromethane-petroleum ether (v1:v2 = 1:1) to obtain the small molecule donor material ZMH-3 (63 mg, 54%). 1 H NMR (CDCl3, 600MHz): δ (ppm) 7.64-7.58 (m, 4H), 7.49 (d, J = 8.4Hz, 4H), 7.31-7.28 (m, 14H), 7.25-7.22 (m, 8H), 7.18 (s, 2 H), 7.15 (d, J=7.2Hz, 8H), 7.10-7.08 (m, 12H), 7.04-7.01 (m, 8H), 6.94-6.92 (m, 6H), 6.72 (d, J=4.8Hz, 2H), 6.65 (s, 2H).

[0039] Example 3

[0040] Preparation of compound ZMH-4

[0041] Under anhydrous conditions, compound (II) (50 mg, 0.065 mmol) and 9-butyl-9H-carbazole-3-carbaldehyde (98 mg, 0.39 mmol) were placed in a 100 mL double-necked reaction flask, and freshly dried p-toluenesulfonic acid (13 mg, 0.074 mmol) was added. The flask was equipped with a Dean-Stark apparatus, and then anhydrous toluene (12 mL) was added to dissolve the compound. Piperidine (0.2 mL) was added as a catalyst, and the mixture was stirred and heated to reflux for 4–6 hours. After the reaction was completed, the mixture was cooled to room temperature, diluted with dichloromethane, washed with water, dried over anhydrous sodium sulfate, and purified by silica gel column chromatography after the solvent was evaporated under reduced pressure. The eluent was dichloromethane-petroleum ether (v1:v2 = 1:1) to obtain the small molecule donor material ZMH-2 (47.5 mg, 43%). 1 H NMR (CDCl3, 600MHz): δ (ppm) 8.41 (s, 2H), 8.29-8.26 (m, 2H), 8.22-8.17 (m, 4H), 7.96-7.87 (m, 6H), 7.72-7.6 5(m, 6H), 7.52-7.50(m, 2H), 7.47-7.43(m, 6H), 7.37-7.34(m, 4H), 7.31(t, J=7.2Hz, 2H), 7.23(t, J=7.8Hz, 2H ), 7.1-7.08(m, 2H), 6.72-6.71(m, 2H), 4.34(t, J=7.2Hz, 4H), 4.27(t, J=7.2Hz, 4H), 3.25(s, 2H), 1.92-1.87( m, 4H), 1.85-1.80 (m, 4H), 1.45-1.41 (m, 4H), 1.38-1.34 (m, 4H), 0.99 (t, J=7.8Hz, 6H), 0.93 (t, J=7.2Hz, 6H).

[0042] Example 4

[0043] Thin-film electron absorption spectra of small molecule donor materials ZMH-3 and ZMH-4 and acceptor material ITIC for solar cells

[0044] Compounds ZMH-3, ZMH-4, and ITIC were dissolved in chloroform solution and spin-coated to prepare thin films, and their electronic absorption spectra were measured.

[0045] Figure 1 Thin-film electron absorption spectra of ZMH-3 and ZMH-4, small molecule donor materials for solar cells, and ITIC, acceptor material.

[0046] Example 5

[0047] Fluorescence emission spectra of thin films blended with small molecule donor materials ZMH-3 and ZMH-4 and acceptor material ITIC for solar cells

[0048] Compounds ZMH-3, ZMH-3:ITIC, ZMH-4, and ZMH-4:ITIC were dissolved in chloroform solution and spin-coated to prepare thin films. The fluorescence emission spectra of the thin films were then measured.

[0049] Figure 2 The images show the fluorescence emission spectra of the small molecule donor materials ZMH-3 and ZMH-4 for solar cells, and their respective blends with the acceptor material ITIC.

[0050] Example 6

[0051] Fabrication of organic solar cell devices

[0052] The battery device is constructed using indium tin oxide (ITO) / PEDOT:PSS / active layer / PFN / Al. ITO is the indium tin oxide conductive glass substrate; poly(3,4-ethylenedichlorothiophene):poly(styrene sulfonate) (PEDOT:PSS) is the hole transport layer (HTL); the active layer is a binary active layer composed of donor ZMH-3 or ZMH-4 and acceptor ITIC; poly[(9,9-bis(3-(N,N-dimethylamino)propyl lentil)-2,7-)-alt-2,7-(9,9-dioctyl lentil) (PFN)] is the electron transport layer (ETL); and Al is the cathode.

[0053] PEDOT:PSS was spin-coated onto ITO glass that had been ultrasonically cleaned with detergent, deionized water, acetone, and isopropanol and then vacuum-dried to prepare a hole transport layer with a thickness of 35–40 nm. Electron donors and acceptors were prepared in ZMH-3:ITIC mass ratios of 1:0.4, 1:0.8, 1:1.2, and 1:1.4, respectively, to form an active layer chloroform solution with a concentration of 16 mg / mL. This solution was then spin-coated onto the hole PEDOT:PSS at room temperature and under a nitrogen atmosphere. On the transport layer, a bulk heterojunction film was formed by spin coating at a speed of 2500 rpm / min for 60 s. Then, it was treated by solvent vapor annealing (SVA) and exposed to tetrahydrofuran vapor for 40 s. PFN was then dissolved in methanol solvent and the above PFN-Br methanol solution was spin-coated onto the active layer of the bulk heterojunction to form the PFN electron transport layer. The spin coating speed was 3000 rpm / min and the spin coating time was 60 s. Finally, aluminum (Al) was deposited on top of the PFN layer by thermal evaporation under vacuum conditions.

[0054] Example 7

[0055] PEDOT:PSS was spin-coated onto ITO glass that had been ultrasonically cleaned with detergent, deionized water, acetone, and isopropanol and then vacuum-dried to prepare a hole transport layer with a thickness of 35–40 nm. Electron donors and acceptors were prepared in ZMH-4:ITIC mass ratios of 1:0.4, 1:0.8, 1:1.2, and 1:1.4, respectively, to form an active layer chloroform solution with a concentration of 16 mg / mL. This solution was then spin-coated onto the hole transport layer PEDOT:PSS at room temperature and under a nitrogen atmosphere. On the transport layer, a bulk heterojunction film was formed by spin coating at a speed of 2500 rpm / min for 60 s. Then, it was treated by solvent vapor annealing (SVA) and exposed to tetrahydrofuran vapor for 40 s. PFN was then dissolved in methanol solvent and the above PFN-Br methanol solution was spin-coated onto the active layer of the bulk heterojunction to form the PFN electron transport layer. The spin coating speed was 3000 rpm / min and the spin coating time was 60 s. Finally, aluminum (Al) was deposited on top of the PFN layer by thermal evaporation under vacuum conditions.

[0056] Example 10

[0057] In this invention, organic solar cells were fabricated using ZMH-3 and ZMH-4 as donor materials and ITIC as acceptor. The binary blended active layers were ZMH-3:IDT-TC (mass ratios of 1:0.4, 1:0.8, 1:1.2, and 1:1.4) and ZMH-4:ITIC (mass ratios of 1:0.4, 1:0.8, 1:1.2, and 1:1.4). The photoelectric conversion efficiency of the devices was tested, and the results are shown in Tables 1 and 2.

[0058] Table 1. Photoelectric parameters of organic solar cells with different mass ratios of active layer ZMH-3: ITIC

[0059]

[0060] a. Photoelectric parameters under optimized conditions;

[0061] Table 2 Photoelectric parameters of organic solar cells with different mass ratios of active layer ZMH-4: ITIC

[0062]

[0063] a. Photoelectric parameters under optimized conditions.

Claims

1. A class of small molecule donor materials ZMH-3 and ZMH-4 for dual-BODIPY-based organic solar cells, characterized in that, Its structural formula is shown below:

2. The method for preparing a type of small molecule donor material for a dual-BODIPY-based organic solar cell as described in claim 1, characterized in that, The preparation method is as follows: BODIPY derivative (I) is catalyzed by FeCl3 to generate bisBODIPY derivative (II), which is then reacted with 4-(N,N-diphenylamino)benzaldehyde and 9-butyl-9H-carbazole-3-carbaldehyde with (II) via Knoevenagel reaction to obtain compounds ZMH-3 and ZMH-4. The reaction formulas for this preparation process are as follows:

3. The method for preparing the small molecule donor materials ZMH-3 and ZMH-4 for a type of dual-BODIPY-based organic solar cell according to claim 2, characterized in that, The feature method includes the following steps: 1) Under nitrogen protection, the BODIPY monomer derivative (I) was dissolved in dry dichloromethane, and a ferric chloride nitromethane solution was added dropwise at -78°C. After the addition was completed, the reaction was carried out for half an hour, and then the mixture was brought up to room temperature. The mixture was extracted with dichloromethane, and the organic layer was dried with anhydrous sodium sulfate, the solvent was removed by vacuum evaporation, and then purified by silica gel column chromatography. The eluent was dichloromethane-petroleum ether v:V = 1:1, to obtain the coupled bisBODIPY compound (II). 2) Under anhydrous conditions, compound (II) was placed in a 100 mL double-necked reaction flask with 4-(N,N-diphenylamino)benzaldehyde and 9-butyl-9H-carbazole-3-carbaldehyde, respectively. Freshly dried p-toluenesulfonic acid was added, followed by 10 mL of anhydrous toluene for dissolution. 0.2 mL of piperidine was added as a catalyst, and the mixture was stirred and heated to reflux for 4–6 hours. After the reaction was completed, the mixture was cooled to room temperature. The mixture was diluted with dichloromethane, washed with water, and the organic layer was dried with anhydrous sodium sulfate. After the solvent was evaporated under reduced pressure, the mixture was purified by silica gel column chromatography with dichloromethane-petroleum ether v:v = 1:1 as the eluent to obtain small molecule donor materials ZMH-3 and ZMH-4.

4. The application of the small molecule donor materials ZMH-3 and ZMH-4 for organic solar cells as described in claim 1, characterized in that, Organic solar cell devices are fabricated using an indium tin oxide (ITO) / polyethoxythiophene (PEDOT): polystyrene sulfonic acid (PSS) / active layer / polyphosphorus derivative (PFN)-Br / Al structure, wherein the active layer includes donor materials and acceptor materials, and the donor materials are small molecule donors ZMH-3 and ZMH-4.

5. The organic solar cell according to claim 4, characterized in that, The donor material for the active layer is ZMH-3 or ZMH-4, and the acceptor material is ITIC.

6. The organic solar cell according to claim 4, characterized in that, The optimal photovoltaic performance of the battery is achieved by blending the binary active layer with ZMH-3:ITIC = 1:1.2 and ZMH-4:ITIC = 1:1.2, resulting in photoelectric conversion efficiencies of 12.26% and 8.23%, respectively.

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