CN111171287A

CN111171287A - Dithia-benzo-dithiophene polymer, preparation method and application thereof

Info

Publication number: CN111171287A
Application number: CN201811328582.0A
Authority: CN
Inventors: 葛子义; 黄佳明; 彭瑞祥; 谢凌超; 宋伟
Original assignee: Ningbo Institute of Material Technology and Engineering of CAS
Current assignee: Ningbo Institute of Material Technology and Engineering of CAS
Priority date: 2018-11-09
Filing date: 2018-11-09
Publication date: 2020-05-19

Abstract

The invention provides a dithiabenzodithiophene polymer, which has a structural formula as shown in the specification,

r1 is alkyl; r2 is alkyl, and n is polymerization degree. The polymer has strong electron donating capability and high carrier mobility, can be used as a donor material of a polymer solar cell, and can improve the short-circuit current density and the open-circuit voltage of a cell device.

Description

Dithia-benzo-dithiophene polymer, preparation method and application thereof

Technical Field

The invention belongs to the technical field of polymers and organic solar cell materials, and particularly relates to a dithiabenzo-dithiophene polymer, a preparation method thereof and application thereof in an organic solar cell.

Background

Polymer Solar Cells (PSCs) have attracted attention in recent decades due to their great potential for low cost, ease of large area, flexible device fabrication, etc.

One of the most important parameters in polymer solar cells, Photoelectric Conversion Efficiency (PCE), is equal to the product of short circuit current (Jsc), open circuit Voltage (VOC) and Fill Factor (FF). Over the years, researchers have promoted the PCE of polymer solar cells from 2% to over 14% by designing new materials, optimizing device structures and processes, and the like. Among them, the ITIC non-fullerene small molecule receptor first reported by professor zhangshiwei has been widely noticed by researchers because of its easy synthesis, adjustability at a molecular level, and the like.

However, non-fullerene small molecule acceptors, such as ITIC, IT-M, IT-4F and the like, have narrow band gaps and absorption ranges of 600-900nm, so that the synthesis of more novel medium and wide band gap donor materials is an effective way for further improving the performance of the polymer solar cell.

Disclosure of Invention

In view of the technical current situation, the invention provides a novel dithiabenzodithiophene polymer which has strong electron donating ability and high carrier mobility, can be used as a donor material of a polymer solar cell, and can improve the short-circuit current density and open-circuit voltage of a cell device.

The dithiabenzo-dithiophene polymer provided by the invention is called PDBT-F for short, and the structural formula of the dithiabenzo-dithiophene polymer is shown as the following formula (I):

wherein R1 is alkyl; r2 is alkyl, and n is polymerization degree.

The R1 is not limited, and preferably, the R1 is a C4-C22 linear alkyl group or a C4-C22 branched alkyl group.

The R2 is not limited, and preferably, the R2 is a C4-C22 linear alkyl group or a C4-C22 branched alkyl group.

Preferably, n is an integer of 5 to 100.

The invention also provides a preparation method of the polymer PDBT-F, as shown in figure 1, under the protection of inert gas, a compound with a structure shown in the following formula (II) and a compound with a structure shown in the following formula (III) are mixed and react under the condition of a catalyst to obtain the polymer shown in the formula (1).

Wherein R1 is alkyl, R2 is alkyl, and Me is methyl.

Preferably, the catalyst is palladium tetratriphenylphosphine.

Preferably, the molar ratio of the catalyst to the compound with the structure of the formula (II) is (0.01-0.1): 1.

As an implementation mode, a compound with a structure of a formula (II), a compound with a structure of a formula (III) and a catalyst are mixed, the mixture reacts for 12h-24h at the temperature of 80-100 ℃, then the mixture is settled in methanol, filtered, sequentially extracted by methanol, acetone and n-hexane, finally extracted by trichloromethane, and finally dried to obtain a compound PDBT-F.

As one implementation, the preparation of a compound of the structure of formula (II) is shown in the reaction scheme of fig. 2, comprising the following steps:

(1) mixing 3-bromothiophene, namely a compound 1 with anhydrous tetrahydrofuran, dripping Lithium Diisopropylamide (LDA) at low temperature, adding bromoalkyl, removing the low temperature, adding deionized water for quenching after the reaction is finished, extracting with dichloromethane, concentrating an organic phase, passing through a petroleum ether column, and distilling under reduced pressure to obtain a colorless transparent liquid compound 2;

(2) mixing the compound 2 with anhydrous tetrahydrofuran, dripping LDA at low temperature, adding trimethyl silicon chloride, removing the low temperature, adding deionized water for quenching after the reaction is finished, extracting with dichloromethane, concentrating an organic phase, and passing through a petroleum ether column to obtain a colorless transparent liquid compound 3;

(3) mixing the compound 3 with anhydrous tetrahydrofuran, dripping N-butyllithium at low temperature, adding N-fluoro-diphenyl sulfonamide (NFSI), removing the low temperature, adding deionized water for quenching after the reaction is finished, extracting with dichloromethane, concentrating an organic phase, and passing through a petroleum ether column to obtain a colorless transparent liquid compound 4;

(4) mixing the compound 4, anhydrous tetrahydrofuran and tetrabutylammonium fluoride (TBAF), adding deionized water for quenching after the reaction is finished, extracting with dichloromethane, concentrating an organic phase, and passing through a petroleum ether column to obtain a colorless transparent liquid compound 5;

(5) mixing the compound 5 with anhydrous tetrahydrofuran, dripping n-butyllithium at low temperature, heating to 50-70 ℃, stirring, adding the compound 6, SnCl2 and HCl, adding deionized water for quenching after the reaction is finished, extracting with dichloromethane, concentrating an organic phase, passing through a petroleum ether column, and drying to obtain a light yellow powder compound 7;

(6) adding the compound 7, chloroform and acetic acid into N-bromosuccinimide (NBS) in batches, reacting in a dark place, adding deionized water for quenching after the reaction is finished, extracting with dichloromethane, concentrating an organic phase, passing through a petroleum ether column, and drying to obtain a light yellow powder compound 8, namely the compound with the structure of the formula (II).

The polymer PDBT-F has the following characteristics:

(1) dithino [2,3-d:2 ', 3 ' -d ' ] benzo [1,2-b:4,5-b ' ] dithiophene (DTBDT) has a longer conjugation length, conjugation area, meaning a stronger electron donating ability and higher carrier mobility, than benzo [1,2-b:4,5-b ' ] dithiophene (BDT).

(2) Fluorine atoms are introduced into the side groups of the polymer, so that the highest molecular occupied orbital (HOMO) of the polymer can be reduced, and higher open-circuit Voltage (VOC) can be obtained; meanwhile, better pi-pi accumulation is formed due to the interaction between hydrogen and fluorine atoms, so that higher short-circuit current density is obtained.

Therefore, compared with the prior art, the polymer PDBT-F can be used as an ideal donor material of a polymer solar cell, and can improve the short-circuit current density and the open-circuit voltage of a solar cell device.

As an implementation mode, the polymer PDBT-F is used as a donor material, IDIC is used as an acceptor material to form a binary polymer solar cell, and the structural formula of the IDIC is as follows

The acceptor material IDIC is preferably doped with PC₇₁BM, constituting a terpolymer solar cell, can expand the absorption range in the visible light region to further increase the short-circuit current density, and on the other hand, it is possible to further improve the short-circuit current density due to PC₇₁BM has higher Lowest Unoccupied Molecular Orbital (LUMO) so as to obtain higher open-circuit voltage and finally obtain more excellent photovoltaic performance, and the strategy of fullerene derivatives and non-fullerene micromolecular acceptors is an effective means for improving the photovoltaic performance of the polymer. The PC₇₁The structural formula of BM is shown in the specification,

drawings

FIG. 1 shows a synthetic route of PDBT-F polymer of the present invention.

FIG. 2 is a scheme showing the synthesis of compound 8 of FIG. 1 according to the present invention.

FIG. 3 is a graph of normalized UV-VIS absorption spectra of the polymer PDBT-F in dilute solution and thin film state in example 1 of the present invention.

FIG. 4 is a thermogravimetric analysis of the polymer PDBT-F in example 1 of the present invention.

FIG. 5 is a differential scanning calorimetry plot of the polymer PDBT-F of example 1 of the present invention.

FIG. 6 is the electrochemical cyclic voltammogram of the polymer PDBT-F in example 1 of the present invention.

FIG. 7 shows that the polymer PDBT-F of example 1 has the structure of ITO/PEDOT: PSS/PDBT-F: IDIC: PC₇₁J-V curve of solar cell device of BM/PDINO/Al.

Detailed Description

The present invention will be described in further detail with reference to the following examples and drawings, which are intended to facilitate the understanding of the present invention and are not intended to limit the present invention in any way.

The test methods in the following examples are conventional methods unless otherwise specified; the materials and reagents are commercially available unless otherwise specified.

Example 1:

in this example, the chemical structure of the dithiabenzodithiophene-based polymer (PDBT-F) is shown in

Wherein R1 is a C8 straight chain alkyl group; r2 is a C8 straight chain alkyl; and n is the degree of polymerization.

As shown in FIGS. 1 and 2, the polymer PDBT-F is specifically prepared as follows:

(1) synthesis of Compound 2

Taking a 250ml three-mouth round-bottom flask, carrying out anhydrous and anaerobic treatment, sequentially adding 10g (0.061mol) of 3-bromothiophene and 100ml of anhydrous tetrahydrofuran as compound 1, dripping LDA36.8ml (0.073mol) at-78 ℃, stirring at low temperature for 20min, adding 16.585g (0.085mol) of bromo-isooctane, removing the low temperature, and reacting overnight; after the reaction, deionized water was added to quench, and the mixture was extracted 3 times with 50ml of dichloromethane, the organic phase was concentrated, passed through a petroleum ether column, and distilled under reduced pressure to obtain 12g of compound 2 as a colorless transparent liquid with a yield of 71.8%.

Nuclear magnetic hydrogen spectrum 1H NMR (400MHz, CDCl3) of this compound 2: δ 7.12(d,1H), δ 6.90(d,1H),2.75(d,2H), δ 1.67(m,1H), δ 1.32(m,8H), δ 0.92(d, 6H).

(2) Synthesis of Compound 3

Taking a 250ml three-mouth round-bottom flask, carrying out anhydrous and anaerobic treatment, sequentially adding 10g (0.036mol) of compound 2 and 100ml of anhydrous tetrahydrofuran, dripping 21.6ml (0.043mol) of LDA at-78 ℃, stirring at low temperature for 20min, adding 5.55g (0.051mol) of trimethylsilyl chloride, removing the low temperature, and reacting overnight; after the reaction was completed, deionized water was added to quench, and the mixture was extracted 3 times with 50ml of dichloromethane, the organic phase was concentrated, and petroleum ether was passed through a column to obtain 11.3g of compound 3 as a colorless transparent liquid with a yield of 90.3%.

Nuclear magnetic hydrogen spectrum 1H NMR (400MHz, CDCl3) of this compound 3: δ 7.00(s,1H),2.75(d,2H), δ 1.67(m,1H), δ 1.32(m,8H), δ 0.92(d,6H), δ 0.29(s, 9H).

(3) Synthesis of Compound 4

Taking a 250ml three-neck round-bottom flask, carrying out anhydrous and anaerobic treatment, sequentially adding 10g (0.029mol) of compound 3 and 100ml of anhydrous tetrahydrofuran, dripping 26.98ml (0.044mol) of n-butyllithium at-78 ℃, stirring at low temperature for 30min, adding 16.34g (0.052mol) of NFSI, removing the low temperature, and reacting overnight; after the reaction was completed, deionized water was added to quench, and the mixture was extracted 3 times with 50ml of dichloromethane, the organic phase was concentrated, and the mixture was subjected to a petroleum ether column chromatography to obtain 6g of compound 4 as a colorless transparent liquid with a yield of 72.2%.

Nuclear magnetic hydrogen spectrum 1H NMR (400MHz, CDCl3) of this compound: δ 682(s,1H),2.62(d,2H), δ 1.67(m,1H), δ 1.32(m,8H), δ 0.92(d,6H), δ 0.29(s, 9H).

(4) Synthesis of Compound 5

Taking a 250ml three-neck round-bottom flask, sequentially adding 5g (0.017mol) of compound 4, 50ml of anhydrous tetrahydrofuran and 20.96ml (0.020mol) of TBAF, and reacting overnight; after the reaction was completed, deionized water was added to quench, and the mixture was extracted 3 times with 50ml of dichloromethane, the organic phase was concentrated, and petroleum ether was passed through a column to give 3.5g of compound 5 as a colorless transparent liquid with a yield of 96.2%.

Nuclear magnetic hydrogen spectrum 1H NMR (400MHz, CDCl3) of this compound 5: δ 6.96(d,1H), δ 6.72(d,1H),2.66(d,2H), δ 1.54(m,1H), δ 1.28(m,8H), δ 0.88(d, 6H).

(5) Synthesis of Compound 7

Taking a 50mL three-neck round-bottom flask, carrying out anhydrous and anaerobic treatment, sequentially adding 0.9g (4.2mmol) of compound 5 and 50mL of anhydrous tetrahydrofuran, dripping 2.2mL (5.5mol) of n-butyllithium at-78 ℃, stirring at low temperature for 20min, gradually heating to 50 ℃, stirring for 1h, adding 0.47g (1.4mmol) of compound 6, continuing stirring for 1h, adding 2.7g (12mmol) of SnCl₂1mL of HCl, and reacting overnight; after the reaction, deionized water was added to quench, and the mixture was extracted 3 times with 50ml of dichloromethane, concentrated in the organic phase, passed through a column with petroleum ether, and dried to obtain 0.8g of a pale yellow powder of compound 7, with a yield of 78.5%.

Nuclear magnetic hydrogen spectrum 1H NMR (400MHz, CDCl3) of this compound 7: δ 7.27(d,2H), δ 7.25(d,2H), δ 7.03(d,2H), δ 2.86(d,4H), δ 1.70(m,2H), δ 1.68-1.38 (m,16H), δ 1.06-0.88 (t, 12H).

(6) Synthesis of Compound 8

Taking a 100ml three-neck flask, adding 0.5g (0.69mmol) of compound 7, 25ml of chloroform and 25ml of acetic acid in turn under an ice water bath, adding 367mg (2mmol) of NBS in batches, and reacting overnight in a dark place; after the reaction is finished, deionized water is added for quenching, 50ml of dichloromethane is used for extraction for 3 times, and the light yellow powder compound 8 is obtained after organic phase concentration, petroleum ether column chromatography and drying.

Nuclear magnetic hydrogen spectrum 1H NMR (400MHz, CDCl3) of this compound 8: δ 7.26(d,2H), δ 7.00(d,2H), δ 2.86(d,4H), δ 1.70(m,2H), δ 1.68-1.38 (m,16H), δ.06-0.88 (t, 12H).

(7) Synthesis of Polymer PDBT-F

The reaction tube was taken out, treated with anhydrous oxygen-free treatment, and 60mg (0.067mmol) of compound 8, 63.34mg (0.067mmol) of compound 9, and 4mg of tetrakis (triphenylphosphine) palladium were added in this order to react at 100 ℃ for 12 hours. Settling in methanol, suction filtering, sequentially extracting with methanol, acetone and n-hexane, finally extracting with chloroform, and spin drying to obtain the compound PDBT-F.

The normalized ultraviolet-visible absorption spectrum of the polymer PDBT-F in the states of dilute solution and thin film is shown in FIG. 3.

The thermogravimetric analysis of the polymer PDBT-F is shown in FIG. 4.

A differential scanning calorimetry chart of the polymer PDBT-F is shown in FIG. 5.

The electrochemical cyclic voltammogram of the PDBT-F polymer is shown in FIG. 6.

The prepared polymer PDBT-F is used for an organic solar cell, wherein an anode adopts ITO, an anode modification layer adopts PEDOT (PolyEthylenedimethylene terephthalate): PSS), the polymer PDBT-F is used as a donor material, and acceptor materials are IDIC (International Density IC) and PC (Poly carbonate))₇₁BM, the cathode modification layer is PDINO, and the cathode is Al.

The structural formula of the IDIC is as follows:

the PC₇₁The structural formula of BM is as follows:

the J-V curve of the prepared ternary photovoltaic device with the structure of ITO/PEDOT: PSS/PDBT-F: IDIC: PC71BM/PDINO/Al is shown in figure 6.

The embodiments described above are intended to illustrate the technical solutions of the present invention in detail, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modification, supplement or similar substitution made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dithiabenzodithiophene polymer, which has the following structural formula (I):

wherein R1 is alkyl; r2 is alkyl, and n is polymerization degree.

2. The dithiabenzodithiophene polymer of claim 1, wherein: and the R1 is C4-C22 straight-chain alkyl or C4-C22 branched-chain alkyl.

3. The dithiabenzodithiophene polymer of claim 1, wherein: and the R2 is C4-C22 straight-chain alkyl or C4-C22 branched-chain alkyl.

4. The dithiabenzodithiophene polymer of claim 1, wherein: and n is an integer of 5-100.

5. The process for producing dithiabenzodithiophene polymer according to any one of claims 1 to 4, wherein: under the protection of inert gas, mixing a compound with a structure shown in the following formula (II) with a compound with a structure shown in the following formula (III), and reacting under the condition of a catalyst to obtain a polymer shown in the formula (1);

wherein R1 is alkyl, R2 is alkyl, and Me is methyl.

6. The process for producing dithiabenzodithiophene polymer according to claim 5, wherein: the catalyst is palladium tetratriphenylphosphine;

7. The process for producing dithiabenzodithiophene polymer according to claim 5, wherein: mixing the compound with the structure of the formula (II), the compound with the structure of the formula (III) and a catalyst, reacting for 12-24 h at 80-100 ℃, then settling in methanol, carrying out suction filtration, sequentially extracting with methanol, acetone and n-hexane, finally extracting with trichloromethane, and spin-drying to obtain the dithiabenzo-dithiophene polymer.

8. The process for producing dithiabenzodithiophene polymer according to claim 5, wherein: the preparation of the compound with the structure of the formula (II) comprises the following steps:

9. Use of the dithiabenzodithiophene polymer of any of claims 1 to 4 as a polymeric solar cell donor material.

10. Use of the dithiabenzodithiophene polymer of claim 9 as a donor material for polymeric solar cells, wherein: the receptor material is IDIC, and the structural formula of the IDIC is as follows

Preferably, the IDIC is doped with PC₇₁BM, the PC₇₁The structural formula of BM is shown in the specification,