CN114805760A

CN114805760A - Condensed ring n-type polymer with asymmetric framework and preparation method and application thereof

Info

Publication number: CN114805760A
Application number: CN202210453755.1A
Authority: CN
Inventors: 段春晖; 吴宝奇; 田士增
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2022-04-27
Filing date: 2022-04-27
Publication date: 2022-07-29

Abstract

The invention discloses a condensed ring n-type polymer with asymmetric framework, a preparation method and application thereof. In the structural formula of the asymmetric-skeleton condensed ring n-type polymer, a copolymerization unit 1 is an A-D1A 'D2-A condensed ring unit, A' and A are electron-deficient units, and D1 and D2 are electron-donating units with different structures; the copolymerized unit 2 is a conjugated aromatic heterocyclic unit. The polymer provided by the invention is in a random structure due to introduction of a condensed ring unit with asymmetric skeleton. The structure can effectively inhibit the aggregation of the polymer, improve the solubility and the solution processability of the polymer in a halogen-free green solvent, and simultaneously can still maintain proper crystallinity to ensure effective charge transmission. In addition, the polymer provided by the invention has a wide absorption range and a high absorption coefficient, can realize better optical absorption complementation and energy level matching with a p-type semiconductor material, and has good photoelectric response performance when being applied to an organic solar cell.

Description

Condensed ring n-type polymer with asymmetric framework and preparation method and application thereof

Technical Field

The invention belongs to the technical field of photoelectric materials and application, and particularly relates to a condensed ring n-type polymer with asymmetric framework, and a preparation method and application thereof.

Background

In recent years, Organic Solar Cells (OSCs) have been developed rapidly, and all-polymer solar cells (all-PSCs) using p-type polymers as donors and n-type polymers as acceptors have attracted more and more attention due to advantages of adjustable complementary absorption between donors and acceptors, good morphological stability, excellent mechanical properties, and the like. However, since the number of the high-efficiency polymer donors/acceptors is small, and the problems of micro-phase separation structure of the photovoltaic active layer, non-ideal charge mobility and the like are faced for a long time, the development is slow, and the energy conversion efficiency is behind that of the PSCs using small-molecule materials as acceptors.

In view of the advantages of strong and broad absorption, suitable energy levels and excellent photovoltaic performance of non-fullerene small molecule receptors, the li-guangfang courier team proposed a "small molecule receptor polymerization" (PSMAs) strategy for the first time in 2017 (angelw.chem.int.ed., 2017,56, 13503). They introduce non-fullerene small molecules into a polymer chain as a structural unit, and the synthesized polymer acceptor PZ1 shows narrow optical band gap and high absorptivity (1.3 multiplied by 10) ⁵ cm ^-1 ) High electron mobility, high device efficiency and the like, and highlights the great potential of the PSMAs strategy in preparing high-efficiency polymer receptors. In particular, in recent two years, the PSMAs strategy has promoted the rapid development of polymer receptors, making PCEs of all-polymer solar cells breakthrough 17%, further from practical applications (Joule,2021,5, 1548). However, such high-efficiency devices are basically manufactured using halogen-containing solvents such as Chloroform (CF), Chlorobenzene (CB), and the like, under an inert gas atmosphere. Such solvents are generally extremely environmentally toxic and are very hazardous to humans. In addition, post-treatment of such solvents also increases costs, which are detrimental to future large-area commercial production of all-PSCs (j.polym.sci.,2022,60, 945). Therefore, the development of a green, safe and sustainable method for preparing high-performance all-PSCs by using a halogen-free green solvent is imperative. To achieve this, the first requirement is that the conjugated polymer has good solubility in green solvents.

The literature research finds that when asymmetric monomers are used for constructing the polymer, the irregular effect of the main chain structure can be achieved due to the uncertainty of the connection position of the monomers in the main chain of the polymer. This non-regular structure is effective in inhibiting aggregation of the polymer, increasing the solubility of the polymer, and achieving processability in halogen-free, green solvents while still maintaining suitable crystallinity to ensure efficient charge transport (Energy environ. sci.,2021,14, 5530). At present, no report is found on the research of introducing a skeleton asymmetric fused ring unit into an n-type polymer as a conjugated backbone. Therefore, by utilizing the construction mode, a novel asymmetric-skeleton polymerized monomer is designed and synthesized, different copolymerization units are selected, the absorption and energy level of the polymer are adjusted, a high-performance polymer receptor capable of being processed by a green solvent is obtained, and the high-efficiency all-polymer solar cell is prepared by processing the green solvent.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a fused ring n-type polymer with asymmetric framework and a preparation method thereof, and expand the application of the fused ring n-type polymer as an acceptor material in an all-polymer solar cell.

The purpose of the invention is realized by the following technical scheme.

The polymer provided by the invention is an n-type polymer obtained by copolymerizing asymmetric fused ring units of a framework and other conjugated aromatic heterocyclic units.

The invention provides a condensed ring n-type polymer with asymmetric framework, which is characterized in that the structural general formula is shown as formula I:

in the formula I, the copolymerized unit 1 is an A-D1A' D2-A type condensed ring unit and is represented by a formula II:

in the formula II, the D1A' D2 unit is selected from any one of the following structural formulas:

wherein, R in the structural formula of the D1A' D2 unit ₁ 、R ₂ 、R ₃ And R ₄ Each independently selected from H, halogen, straight chain or branched chain alkyl or alkoxy or alkylthio group with 1-50 carbon atoms or alkyl substituted aryl; the alkyl in the alkyl-substituted aryl is a straight chain or branched chain alkyl with the carbon atom number of 1-50, and the aryl is a benzene ring or a thiophene ring; the halogen is F, Cl or I; in the structural formula, X and Y independently represent O, S or Se atom; the dotted line in the structural formula D1A' D2 represents the attachment site to the A unit;

in the formula II, the A unit is selected from any one of the following structural formulas:

dotted line in the A unit structural formula: (ii) denotes the attachment site of the A unit to the D1A' D2 unit; ② represents a connecting site of the A unit and the copolymerization unit 2;

in the formula I, a copolymerization unit 2 is a conjugated aromatic heterocyclic unit and is selected from any one of the following structural formulas:

wherein R in the structural formula of the copolymerization unit 2 is independently selected from H, halogen, straight-chain or branched-chain alkyl or alkoxy or alkylthio with 1-50 carbon atoms, or alkylsilyl or alkyl-substituted aryl; the alkyl in the alkyl-substituted aryl is a straight chain or branched chain alkyl with the carbon atom number of 1-50, and the aryl is a benzene ring or a thiophene ring; the halogen is F, Cl or I; in the structural formula, M represents C, O or S atom; in the structural formula, Z represents H, F or Cl atom; the dotted line in the structural formula of the copolymerization unit 2 represents a connection site with the copolymerization unit 1;

wherein n is the number of the polymer repeating units and is a natural number of 1-10000.

Further, one structure of the copolymerization unit 1 is shown as a formula III:

wherein R in the formula III ₅ 、R ₆ 、R ₇ Each independently selected from H, halogen, straight chain or branched chain alkyl or alkoxy or alkylthio group with 1-50 carbon atoms or alkyl substituted aryl; the alkyl in the alkyl-substituted aryl is a straight chain or branched chain alkyl with the carbon atom number of 1-50, and the aryl is a benzene ring or a thiophene ring; the halogen is F, Cl or I; in the structural formula, X and Y independently represent O, S or Se atom; the dotted line in said formula III indicates the attachment site to the copolymerizing unit 2.

Further, the polymer in the formula I is shown as a formula IV:

wherein R in the formula IV ₅ 、R ₆ 、R ₇ Is as defined for R in formula III ₅ 、R ₆ 、R ₇ (ii) a In the structural formula, X and Y independently represent O, S or Se atom; n is a natural number of 1 to 10000.

Further, the number of carbon atoms of the alkyl straight chain and the branched chain of the polymer is 1-50.

The invention provides a method for preparing the asymmetric fused ring n-type polymer with the skeleton, which comprises the following steps:

in an inert gas atmosphere, mixing a monomer of a copolymerization unit 1 and a monomer of a copolymerization unit 2 in a molar ratio of 1:1 in a reaction solvent, carrying out polymerization reaction under the catalysis of a catalyst, and purifying to obtain the copolymer; the reaction solvent comprises at least one of toluene, o-xylene or chlorobenzene; the catalyst comprises a palladium catalyst; the reaction temperature of the polymerization reaction is 100-120 ℃, the reaction time is 12-72 h, and the stirring speed is 500-1000 rpm; the mixing mode is physical blending; the purification mode comprises one or more of filtration, column chromatography and Soxhlet extraction dialysis.

The fused ring n-type polymer with asymmetric framework provided by the invention can be used as an acceptor material to be applied to preparation of all-polymer solar cells.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the invention designs a condensed ring n-type polymer material with asymmetric framework;

(2) the main chain of the polymer obtained by the invention is of a random structure, so that the aggregation of the polymer can be effectively inhibited, and the solubility and the processability of the material in a halogen-free green solvent are improved;

(3) the fused ring n-type polymer with asymmetric framework can be processed by green solvent and applied to all-polymer solar cells.

Drawings

FIG. 1 is a schematic chemical structure of a polymer donor PM 6.

Fig. 2 is a schematic view of the structures of all-polymer solar cell devices used in examples 9 to 12 and comparative example 1.

Fig. 3 is a voltage-current density curve of an all-polymer solar cell based on PM6: P1 as an active layer prepared by different solvent processes.

Fig. 4 is a wavelength-external quantum efficiency curve of an all-polymer solar cell based on PM6: P1 as an active layer prepared by different solvent processes.

Fig. 5 is a voltage-current density curve of an all-polymer solar cell based on PM6: P2 as an active layer prepared by different solvent processes.

Fig. 6 is a wavelength-external quantum efficiency curve of an all-polymer solar cell based on PM6: P2 as an active layer prepared by different solvent processes.

Fig. 7 is a voltage-current density curve of an all-polymer solar cell based on PM6: P3 as an active layer prepared by different solvent processes.

Fig. 8 is a wavelength-external quantum efficiency curve of all polymer solar cells based on PM6: P3 as active layers prepared by different solvent processes.

Fig. 9 is a voltage-current density curve of an all-polymer solar cell based on PM6: P4 as an active layer prepared by different solvent processes.

Fig. 10 is a wavelength-external quantum efficiency curve of all-polymer solar cells based on PM6: P4 as active layers prepared by different solvent processes.

Fig. 11 is a voltage-current density curve of an all-polymer solar cell based on PM6: PYT as an active layer prepared by different solvent processes.

Fig. 12 is a wavelength-external quantum efficiency curve of an all-polymer solar cell based on PM6: PYT as an active layer prepared by different solvent processes.

Detailed Description

The following description of the embodiments of the present invention is provided in connection with the accompanying drawings and examples, but the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art.

The practice of the present invention may employ conventional techniques of polymer chemistry within the skill of the relevant art. In the following examples, efforts are made to ensure accuracy with respect to numbers used (including amounts, temperature, reaction time, etc.) but some experimental errors and deviations should be accounted for. The temperatures used in the following examples are expressed in degrees Celsius and the pressures are at or near atmospheric. All solvents used were either analytically pure or chromatographically pure, and all reactions were carried out under an inert gas atmosphere. All reagents were obtained commercially unless otherwise indicated.

Example 1

Preparation of polymerized monomer M1

The chemical synthetic route, specific reaction steps and reaction conditions of M1 are as follows.

(1)

Intermediates

3, 5 and 10 were prepared according to the methods reported in the literature (synthesis reference of 3: Macromolecules,2019,52, 4447-4457; synthesis reference of 5: Joule,2019,3, 1140-1151; synthesis reference of 10: adv. Mater.,2020,32, 2005942). Other reagents required for each reaction step are commercially available.

(2) Synthesis of intermediate 2

In a 100mL two-necked flask, trifluoromethanesulfonic acid (CF) was added ₃ SO ₃ H) (18mL, 0.204mol), fuming nitric acid (3mL, 0.051mol) was slowly added dropwise at 0 deg.C, then intermediate 1(5.0g, 0.017mol) was added in 5 portions, followed by warming to 50 deg.C and stirring for reaction for 18 h. After the reaction was stopped and the temperature was cooled to room temperature, the reaction solution was added dropwise to an ice-water bath, and the pH was adjusted to 7 by an aqueous sodium hydroxide solution, whereupon a yellow solid precipitated. The crude solid product obtained by suction filtration was washed several times with deionized water and then recrystallized from toluene to give 4.68g of a pale yellow solid powder with a yield of 72%.

(3) Synthesis of intermediate 4

Under the protection of nitrogen, intermediate 2(2.0g, 5.20mmol), intermediate 3(2.25g, 4.16mmol) and catalyst Pd ₂ (dba) ₃ (95.2mg, 0.104mmol) and ligand P (o-tol) ₃ (253.2mg, 0.832mmol) was dissolved in 30mL of toluene and reacted at 110 ℃ for 24 h. After the reaction was stopped, it was extracted with Dichloromethane (DCM), and the organic phase was collected. Purification by column chromatography gave 1.10g of a tan solid in 48% yield.

(4) Synthesis of intermediate 6

Under the protection of nitrogen, intermediate 4(1.0g, 1.80mmol), intermediate 5(1.58g, 2.70mmol) and Pd are added ₂ (dba) ₃ (33.0mg, 0.036mmol) and P (o-tol) ₃ (87.7mg, 0.288mmol) was dissolved in 20mL of toluene and reacted at 110 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 1.18g of a red crystalline solid in 85% yield.

(5) Synthesis of intermediate 7

Intermediate 6(990.0mg, 1.29mmol) and triphenylphosphine (PPh) were added under nitrogen protection ₃ ) (1.58g, 12.90mmol) was dissolved in 10mL of ultra-dry o-dichlorobenzene and reacted at 180 ℃ for 24 h. After the reaction is stopped, the crude product can be obtained by column chromatography purificationThe blackish green solid was 860.0mg, crude yield 95%. The product can be directly used for the next reaction without more elaborate purification.

(6) Synthesis of intermediate 8

Under nitrogen protection, intermediate 7(860.0mg, 1.22mmol), 11- (bromomethyl) tricosane (2.04g, 4.88mmol), cesium carbonate (Cs) ₂ CO ₃ ) (1.59g, 4.88mmol) and potassium iodide (203.0mg, 1.22mmol) were dissolved in 30mL of ultra dry N, N-Dimethylformamide (DMF) and reacted at 90 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 720.0mg of a yellow viscous liquid in 43% yield.

(7) Synthesis of intermediate 9

DMF (0.6mL, 7.50mmol) was added to a 100mL two-necked flask under nitrogen, and phosphorus oxychloride (POCl) was slowly added dropwise at 0 deg.C ₃ ) (0.7mL, 7.50mmol) and stirring at this temperature was continued for 0.5 h. A solution of intermediate 8(690.0mg, 0.50mmol) in 1, 2-dichloroethane (20mL) was then added dropwise and the reaction continued at 0 ℃ for 2 h. Then the temperature is raised to 90 ℃, and the reaction is stirred for 16 hours. Then, saturated aqueous sodium bicarbonate solution was added thereto, and the mixture was stirred and reacted for 2 hours. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 574.0mg of an orange viscous liquid with a yield of 80%.

(8) Synthesis of monomer M1

Intermediate 9(526.0mg, 0.37mmol) and intermediate 10(405.0mg, 1.48mmol) were dissolved in 30mL of chloroform under nitrogen, stirred for 15min, 1mL of pyridine was added dropwise, and the mixture was reacted at 65 ℃ for 18 h. After the reaction was stopped, a large amount of chloroform solvent was first removed by spinning, and then the remaining mixture was settled in methanol. The collected solid was filtered and purified by column chromatography to obtain 633.0mg of a black solid with a yield of 88%.

Example 2

Preparation of polymerized monomer M2

The chemical synthetic route, specific reaction steps and reaction conditions of M2 are as follows.

(1) Intermediates 8 and 10 are as described in example 1. Other reagents required for each reaction step are commercially available.

(2) Synthesis of intermediate 11

Intermediate 8(1.38g, 1.0mmol) was charged into a 200mL two-necked flask under nitrogen, 80mL of acetic acid was added, and zinc particles (1.31g, 20.0mmol) were added, followed by warming to 100 ℃ and stirring for 4 h. After the reaction was stopped and cooled to room temperature, solid impurities were first filtered, the filtrate was poured into water, the pH was adjusted to be alkaline by an aqueous sodium hydroxide solution, and extraction was performed with ethyl acetate. The collected organic layer was dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure. The resulting brown crude liquid was placed directly in a 100mL two-neck flask without further purification, and a solution of ethylene glycol (2.0mmol, 40 wt.% in water) and 50mL of ethanol were added and reacted with stirring at room temperature for 16 h. After the reaction was stopped, it was extracted with Dichloromethane (DCM), and the organic phase was collected. Purification by column chromatography gave 480.0mg of a yellow viscous liquid in 35% yield.

(3) Synthesis of intermediate 12

Intermediate 11(412.0mg, 0.30mmol) was dissolved in 25mL of anhydrous tetrahydrofuran under nitrogen. The temperature was reduced to-78 deg.C and LDA (1M) (1.5mL,1.50mmol) was slowly added dropwise with continued stirring for 2 h. Thereafter, DMF (0.17mL,2.20mmol) was slowly added dropwise and the reaction was stirred at this temperature for an additional 30 min. Finally, the reaction was continued for 1h while warming to room temperature. After the reaction was complete, water was added to quench, DCM was used for extraction and the organic phase was collected. Purification by column chromatography gave 385.7mg of an orange viscous liquid with a yield of 90%.

(4) Synthesis of monomer M2

Intermediate 12(357.0mg, 0.25mmol) and intermediate 10(273.1mg, 1.0mmol) were dissolved in 30mL of chloroform under nitrogen, stirred for 15min, and 1mL of pyridine was added dropwise, followed by reaction at 65 ℃ for 18 h. After the reaction was stopped, a large amount of chloroform solvent was first removed by spinning, and then the remaining mixture was settled in methanol. The solid collected by filtration was purified by column chromatography to give 450.7mg of a black solid with a yield of 93%.

Example 3

Preparation of polymerized monomer M3

The chemical synthetic route, specific reaction steps and reaction conditions of M3 are as follows.

(1) Intermediate 13 was prepared according to literature reported methods (synthesis of 13: ACS appl. polym. mater.,2019,1,2302).

Intermediates

3, 5 and 10 were as described in example 1. Other reagents required for each reaction step are commercially available.

(2) Synthesis of intermediate 14

Under the protection of nitrogen, intermediate 13(3.66g, 5.20mmol), intermediate 3(2.25g, 4.16mmol) and Pd are added ₂ (dba) ₃ (95.2mg, 0.104mmol) and P (o-tol) ₃ (253.2mg, 0.832mmol) was dissolved in 30mL of toluene and reacted at 110 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 1.60g of a yellow viscous liquid with a yield of 44%.

(3) Synthesis of intermediate 15

Under the protection of nitrogen, intermediate 14(1.58g, 1.80mmol), intermediate 5(1.58g, 2.70mmol) and Pd were added ₂ (dba) ₃ (33.0mg, 0.036mmol) and P (o-tol) ₃ (87.7mg, 0.288mmol) was dissolved in 20mL of toluene and reacted at 110 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 1.63g of an orange-yellow viscous liquid with a yield of 83%.

(4) Synthesis of intermediate 16

Intermediate 15(1.41g, 1.29mmol) and PPh were added under nitrogen protection ₃ (1.58g, 12.90mmol) was dissolved in 10mL of ultra-dry o-dichlorobenzene and reacted at 180 ℃ for 24 h. After the reaction was stopped, purification was performed by column chromatography to obtain 1.26g of a crude product as a dark green solid with a crude yield of 95%. The product can be directly used for the next reaction without more elaborate purification.

(5) Synthesis of intermediate 17

Under the protection of nitrogen, intermediate 16(1.25g, 1.22mmol), 11- (bromomethyl) tricosane (2.04g, 4.88mmol), Cs ₂ CO ₃ (1.59g, 4.88mmol) and potassium iodide (203.0mg, 1.22mmol) were dissolved in 30mL of ultra dry DMF and reacted at 90 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 932.2mg of an orange viscous liquid with a yield of 45%.

(6) Synthesis of intermediate 18

DMF (0.6mL, 7.50mmol) was added to a 100mL two-necked flask under nitrogen, and POCl was slowly added dropwise at 0 deg.C ₃ (0.7mL, 7.50mmol) and stirring at this temperature was continued for 0.5 h. A solution of intermediate 17(850.0mg, 0.50mmol) in 1, 2-dichloroethane (20mL) was then added dropwise and the reaction continued at 0 ℃ for 2 h. Then the temperature is increased to 90 ℃, and the reaction is stirred for 16 h. Then, saturated aqueous sodium bicarbonate solution was added thereto, and the mixture was stirred and reacted for 2 hours. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 728.0mg of an orange viscous liquid with 83% yield.

(7) Synthesis of monomer M3

Intermediate 18(649.0mg, 0.37mmol) and intermediate 10(405.0mg, 1.48mmol) were dissolved in 30mL of chloroform under nitrogen, stirred for 15min, 1mL of pyridine was added dropwise, and the mixture was reacted at 65 ℃ for 18 h. After the reaction was stopped, a large amount of chloroform solvent was first removed by spinning, and then the remaining mixture was settled in methanol. The collected solid was filtered and purified by column chromatography to obtain 754.0mg of a black solid with a yield of 90%.

Example 4

Preparation of polymerized monomer M4

The chemical synthetic route, specific reaction steps and reaction conditions of M4 are as follows.

(1) The intermediate 20 was prepared according to literature reported methods (reference for synthesis of 20: J Phys. org. chem.,2020,33, e 4063).

Intermediates

2, 5 and 10 were as described in example 1. Other reagents required for each reaction step are commercially available.

(2) Synthesis of intermediate 19

Under the protection of nitrogen, intermediate 2(2.0g, 5.20mmol), intermediate 5(2.43g, 4.16mmol) and Pd are added ₂ (dba) ₃ (95.2mg, 0.104mmol) and P (o-tol) ₃ (253.2mg, 0.832mmol) was dissolved in 30mL of toluene and reacted at 110 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 1.24g of a tan solid in 50% yield.

(3) Synthesis of intermediate 21

Under the protection of nitrogen, intermediate 19(1.08g, 1.80mmol), intermediate 20(1.57g, 2.70mmol) and Pd are added ₂ (dba) ₃ (33.0mg, 0.036mmol) and P (o-tol) ₃ (87.7mg, 0.288mmol) was dissolved in 20mL of toluene and reacted at 110 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 1.09g of a greenish black solid in 75% yield.

(4) Synthesis of intermediate 22

Intermediate 21(1.04g, 1.29mmol) and PPh were added under nitrogen protection ₃ (1.58g, 12.90mmol) was dissolved in 10mL of ultra-dry o-dichlorobenzene and reacted at 180 ℃ for 24 h. After the reaction was stopped, purification was performed by column chromatography to obtain 941.0mg of a crude product as a dark green solid with a crude yield of 98%. The product can be directly used for the next reaction without more elaborate purification.

(5) Synthesis of intermediate 23

Under the protection of nitrogen, intermediate 22(908.0mg, 1.22mmol), 11- (bromomethyl) tricosane (2.04g, 4.88mmol), Cs ₂ CO ₃ (1.59g, 4.88mmol) and potassium iodide (203.0mg, 1.22mmol) were dissolved in 30mL of ultra dry DMF and reacted at 90 ℃ for 24 h. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 813.0mg as a dark red solid with a yield of 47%.

(6) Synthesis of intermediate 24

DMF (0.6mL, 7.50mmol) was charged under nitrogen to a 100mL two-necked flaskSlowly dropping POCl at the temperature of 0 DEG C ₃ (0.7mL, 7.50mmol) and stirring at this temperature was continued for 0.5 h. A solution of intermediate 23(709.0mg, 0.50mmol) in 1, 2-dichloroethane (20mL) was then added dropwise and the reaction continued at 0 ℃ for 2 h. Then the temperature is raised to 90 ℃, and the reaction is stirred for 16 hours. Then, saturated aqueous sodium bicarbonate solution was added thereto, and the mixture was stirred and reacted for 2 hours. After the reaction was stopped, it was extracted with DCM and the organic phase was collected. Purification by column chromatography gave 641.0mg of an orange solid in 87% yield.

(7) Synthesis of monomer M4

Intermediate 24(545.0mg, 0.37mmol) and intermediate 10(405.0mg, 1.48mmol) were dissolved in 30mL of chloroform under nitrogen, stirred for 15min, 1mL of pyridine was added dropwise, and the mixture was reacted at 65 ℃ for 18 h. After the reaction was stopped, a large amount of chloroform solvent was first removed by spinning, and then the remaining mixture was settled in methanol. The collected solid was filtered and purified by column chromatography to obtain 609.0mg of a black solid with a yield of 83%.

Example 5

By way of example, the fused ring n-type polymer P1, which is asymmetric based on the backbone, has the following structural formula:

the following examples illustrate the preparation of representative n-type polymers based on backbone asymmetric fused ring units as proposed by the present invention, but the present invention is not limited to the examples given.

(1) The polymerized monomer M5, the catalyst tetrakis (triphenylphosphine) palladium and o-xylene were all obtained commercially.

(2) Preparation of Polymer P1

Monomer M1(58.34mg, 0.03mmol), monomer M5(12.30mg, 0.03mmol) and catalyst Pd (PPh) were weighed accurately under nitrogen ₃ ) ₄ (0.7mg, 0.0006mmol) in 2mL of UltrafiltrationThe reaction was carried out at 110 ℃ for 45min with dry o-xylene. The reaction was stopped, cooled to room temperature, the polymer was precipitated in anhydrous methanol, the solid was collected and placed in a soxhlet extractor. Under the protection of argon, sequentially extracting by methanol, acetone, normal hexane and trichloromethane. Thereafter, the chloroform fraction was collected, most of the solvent was removed by distillation under the reduced pressure, the remaining small portion was settled in methanol, and the solid was collected by mobile phase filtration and finally dried to obtain polymer P1 in a yield of 45.0mg and a yield of 80%. The polymer P1 can be dissolved in common solvents such as chloroform, chlorobenzene and the like, and can also be smoothly dissolved in halogen-free green solvents such as tetrahydrofuran, toluene, o-xylene and the like.

Example 6

By way of example, the fused ring n-type polymer P2, which is asymmetric based on the backbone, has the following structural formula:

(1) Preparation of Polymer P2

Monomer M2(58.16mg, 0.03mmol), monomer M5(12.30mg, 0.03mmol) and Pd (PPh) were weighed accurately under nitrogen ₃ ) ₄ (0.7mg, 0.0006mmol) in 2mL of ultra dry o-xylene and reacted at 110 ℃ for 45 min. The reaction was stopped, cooled to room temperature, the polymer was precipitated in anhydrous methanol, the solid was collected and placed in a soxhlet extractor. Under the protection of argon, sequentially extracting by methanol, acetone, normal hexane and trichloromethane. Thereafter, the chloroform fraction was collected, most of the solvent was removed by distillation under reduced pressure, the remaining small amount was precipitated in methanol, the solid was collected by filtration through a mobile phase, and finallyAfter drying, polymer P2 was obtained in a yield of 47.5mg and 85% yield. The polymer P2 can be dissolved in common solvents such as chloroform, chlorobenzene and the like, and can also be smoothly dissolved in halogen-free green solvents such as tetrahydrofuran, toluene, o-xylene and the like.

Example 7

By way of example, the fused ring n-type polymer P3, which is asymmetric based on the backbone, has the following structural formula:

(1) Preparation of Polymer P3

Monomer M3(67.93mg, 0.03mmol), monomer M5(12.30mg, 0.03mmol) and Pd (PPh) were weighed accurately under nitrogen ₃ ) ₄ (0.7mg, 0.0006mmol) in 2mL of ultra dry o-xylene and reacted at 110 ℃ for 45 min. The reaction was stopped, cooled to room temperature, the polymer was precipitated in anhydrous methanol, the solid was collected and placed in a soxhlet extractor. Under the protection of argon, sequentially extracting by methanol, acetone, normal hexane and trichloromethane. Thereafter, the chloroform fraction was collected, most of the solvent was removed by distillation under the reduced pressure, the remaining small portion was settled in methanol, and the solid was collected by mobile phase filtration and finally dried to obtain polymer P3 in a yield of 59.1mg and 90% yield. The polymer P3 can be dissolved in common solvents such as chloroform, chlorobenzene and the like, and can also be smoothly dissolved in halogen-free green solvents such as tetrahydrofuran, toluene, o-xylene and the like.

Example 8

By way of example, the fused ring n-type polymer P4, which is asymmetric based on the backbone, has the following structural formula:

(1) Preparation of Polymer P4

Monomer M4(59.51mg, 0.03mmol), monomer M5(12.30mg, 0.03mmol) and Pd (PPh) were weighed accurately under nitrogen ₃ ) ₄ (0.7mg, 0.0006mmol) in 2mL of ultra dry o-xylene and reacted at 110 ℃ for 45 min. The reaction was stopped, cooled to room temperature, the polymer was precipitated in anhydrous methanol, the solid was collected and placed in a soxhlet extractor. Under the protection of argon, sequentially extracting by methanol, acetone, normal hexane and chloroform. Thereafter, the chloroform fraction was collected, most of the solvent was removed by distillation under the reduced pressure, the remaining small portion was settled in methanol, and the solid was collected by mobile phase filtration and finally dried to obtain polymer P4 in a yield of 50.4mg and 88% yield. The polymer P4 can be dissolved in common solvents such as chloroform, chlorobenzene and the like, and can also be smoothly dissolved in halogen-free green solvents such as tetrahydrofuran, toluene, o-xylene and the like.

Example 9

The application of the asymmetric condensed ring n-type polymer based on the skeleton in the all-polymer solar cell. By way of example, the polymer P1 selected for use in the following examples has the following structural formula:

an all-polymer solar cell is prepared by taking the exemplified polymer P1 as a polymer acceptor and PM6 as a donor (the structural formula is shown in figure 1). The following examples illustrate the proposed condensed ring n-type polymers based on backbone asymmetry and their application process in organic opto-electronic devices, but the invention is not limited to these examples.

PM 6P 1 blended active layers were processed from the halogen-containing solvent Chloroform (CF) and the green non-halogen solvents Tetrahydrofuran (THF), toluene (toluene), o-xylene (o-xylene), respectively. And then, respectively using the corresponding active layers for preparing the device. The specific preparation process of the device is as follows:

and (3) a 40nm PEDOT (polymer ethylene terephthalate) (PSS) hole transport layer is spin-coated on the ITO, then a mixed light active layer of a polymer donor PM6 and a polymer acceptor P1 with the thickness of about 100nm is spin-coated, then quaternary ammonium bromide (PFN-Br) of amido polyfluorene with the thickness of about 5nm is spin-coated to be used as a cathode interface layer, and then an Ag layer with the thickness of 100nm is vapor-deposited, so that the preparation of the device is completed.

The all-polymer solar cell sequentially comprises a transparent conductive anode, an anode interface layer, a donor/acceptor active layer, a cathode interface layer and a cathode from bottom to top (the cell structure is shown in figure 2). A voltage-current density characteristic test (see fig. 3) and a wavelength-external quantum efficiency test (see fig. 4) were performed. The performance parameters of the device are shown in Table 1, and the Table 1 is a performance parameter table of ITO/PEDOT, PSS/PM6, P1/PFN-Br/Ag of all-polymer solar cell devices processed by different solvents.

Table 1 device parameters of different solvent processed all polymer solar cells based on PM6: P1 as active layer

Example 10

The application of a condensed ring n-type polymer based on skeleton asymmetry in an all-polymer solar cell. By way of example, the polymer P2 selected for use in the following examples has the following structural formula:

an all-polymer solar cell was prepared using the exemplified polymer P2 as the polymer acceptor and PM6 as the donor. The following examples illustrate the proposed condensed ring n-type polymers based on backbone asymmetry and their application process in organic opto-electronic devices, but the invention is not limited to these examples.

PM 6P 2 blended active layers were processed from the halogen-containing solvent Chloroform (CF) and the green non-halogen solvents Tetrahydrofuran (THF), toluene (toluene), o-xylene (o-xylene), respectively. And then, respectively using the active layers obtained correspondingly for preparing the device. The specific preparation process of the device is as follows:

and (3) a 40nm PEDOT (polymer ethylene terephthalate) (PSS) hole transport layer is spin-coated on the ITO, then a mixed optical active layer of a polymer donor PM6 and a polymer acceptor P2 with the thickness of about 100nm is spin-coated, then PFN-Br with the thickness of about 5nm is spin-coated to serve as a cathode interface layer, and then an Ag layer with the thickness of 100nm is vapor-deposited, so that the preparation of the device is completed.

The all-polymer solar cell sequentially comprises a transparent conductive anode, an anode interface layer, a donor/acceptor active layer, a cathode interface layer and a cathode from bottom to top. A voltage-current density characteristic test (see fig. 5) and a wavelength-external quantum efficiency test (see fig. 6) were performed. The performance parameters of the device are shown in Table 2, and the table 2 is a performance parameter table of ITO/PEDOT, PSS/PM6, P2/PFN-Br/Ag of all-polymer solar cell devices processed by different solvents.

Table 2 device parameters of all-polymer solar cells based on PM6: P2 as active layer for different solvent processes

Example 11

The application of a condensed ring n-type polymer based on skeleton asymmetry in an all-polymer solar cell. By way of example, the polymer P3 selected for use in the following examples has the following structural formula:

an all-polymer solar cell was prepared using the exemplified polymer P3 as the polymer acceptor and PM6 as the donor. The following examples illustrate the proposed condensed ring n-type polymers based on backbone asymmetry and their application process in organic opto-electronic devices, but the invention is not limited to these examples.

PM 6P 3 blended active layers were processed from the halogen-containing solvent Chloroform (CF) and the green non-halogen solvents Tetrahydrofuran (THF), toluene (toluene), o-xylene (o-xylene), respectively. And then, respectively using the corresponding active layers for preparing the device. The specific preparation process of the device is as follows:

and (3) a 40nm PEDOT (polymer ethylene terephthalate) (PSS) hole transport layer is spin-coated on the ITO, then a mixed optical active layer of a polymer donor PM6 and a polymer acceptor P3 with the thickness of about 100nm is spin-coated, then PFN-Br with the thickness of about 5nm is spin-coated to serve as a cathode interface layer, and then an Ag layer with the thickness of 100nm is vapor-deposited, so that the preparation of the device is completed.

The all-polymer solar cell sequentially comprises a transparent conductive anode, an anode interface layer, a donor/acceptor active layer, a cathode interface layer and a cathode from bottom to top. A voltage-current density characteristic test (see fig. 7) and a wavelength-external quantum efficiency test (see fig. 8) were performed. The performance parameters of the device are shown in Table 3, and Table 3 is a table of the performance parameters of ITO/PEDOT, PSS/PM6, P3/PFN-Br/Ag of all-polymer solar cell devices processed by different solvents.

Table 3 device parameters of different solvent processed all polymer solar cells based on PM6: P3 as active layer

Example 12

The application of a condensed ring n-type polymer based on skeleton asymmetry in an all-polymer solar cell. By way of example, the polymer P4 selected for use in the following examples has the formula:

an all-polymer solar cell was prepared using the exemplified polymer P4 as the polymer acceptor and PM6 as the donor. The following examples illustrate the proposed condensed ring n-type polymers based on backbone asymmetry and their application process in organic opto-electronic devices, but the invention is not limited to these examples.

PM 6P 4 blended active layers were processed from the halogen-containing solvent Chloroform (CF) and the green non-halogen solvents Tetrahydrofuran (THF), toluene (toluene), o-xylene (o-xylene), respectively. And then, respectively using the corresponding active layers for preparing the device. The specific preparation process of the device is as follows:

and (3) a 40nm PEDOT (polymer ethylene terephthalate) (PSS) hole transport layer is spin-coated on the ITO, then a mixed optical active layer of a polymer donor PM6 and a polymer acceptor P4 with the thickness of about 100nm is spin-coated, then PFN-Br with the thickness of about 5nm is spin-coated to serve as a cathode interface layer, and then an Ag layer with the thickness of 100nm is vapor-deposited, so that the preparation of the device is completed.

The all-polymer solar cell sequentially comprises a transparent conductive anode, an anode interface layer, a donor/acceptor active layer, a cathode interface layer and a cathode from bottom to top. A voltage-current density characteristic test (see fig. 9) and a wavelength-external quantum efficiency test (see fig. 10) were performed. The performance parameters of the device are shown in Table 4, and the table 4 is a table of the performance parameters of ITO/PEDOT, PSS/PM6, P4/PFN-Br/Ag of all-polymer solar cell devices processed by different solvents.

Table 4 device parameters of different solvent processed all polymer solar cells based on PM6: P4 as active layer

Comparative example 1

In order to further illustrate the application potential of the condensed ring n-type polymer with asymmetric framework in the preparation of all-polymer solar cells through green solvent processing, the reported condensed ring n-type polymer with symmetric framework is selected as a control, and the application of the condensed ring n-type polymer in all-polymer solar cells is researched. By way of example, the backbone-symmetric polymer PYT (PYT, Joule,2020,4,1070), selected for the following comparative examples, has the following structure:

an all-polymer solar cell was prepared using the exemplified polymer PYT as the polymer acceptor and PM6 as the donor. The following comparative examples will illustrate the selected backbone-symmetric polymer PYT and its application process in organic opto-electronic devices, but the invention is not limited to the examples given.

PYT has good solubility in Chloroform (CF); limited solubility in o-xylene (o-xylene); the solubility in green solvents such as Tetrahydrofuran (THF) and toluene (tolumen) is poor, and the device is not easy to process and prepare. Therefore, the device used for CF and o-xylene processing only is prepared by the following steps:

and (3) a 40nm PEDOT (polymer ethylene terephthalate) (PSS) hole transport layer is spin-coated on the ITO, a mixed optical active layer of a polymer donor PM6 and a polymer acceptor PYT with the thickness of about 100nm is spin-coated, PFN-Br with the thickness of about 5nm is spin-coated to serve as a cathode interface layer, and an Ag layer with the thickness of 100nm is evaporated to complete the preparation of the device.

The all-polymer solar cell sequentially comprises a transparent conductive anode, an anode interface layer, a donor/acceptor active layer, a cathode interface layer and a cathode from bottom to top. A voltage-current density characteristic test (see fig. 11) and a wavelength-external quantum efficiency test (see fig. 12) were performed. The performance parameters of the device are shown in Table 5, and Table 5 is a table of the performance parameters of ITO/PEDOT, PSS/PM6, PYT/PFN-Br/Ag of all-polymer solar cell devices processed by different solvents.

Table 5 device parameters of different solvent processed all polymer solar cells based on PM6: PYT as active layer

The above data indicate that the backbone symmetric fused ring n-type polymer, although having a higher PCE under halogen-containing solvent processing conditions, has poor solubility in green solvents, and thus it is not easy to prepare high-performance green solvent processable all-polymer solar cell devices. In contrast, the asymmetric fused ring n-type polymer provided by the invention has a random structure in the main chain, so that the aggregation of the polymer can be effectively inhibited, and the solubility and the processability of the material in a halogen-free green solvent are improved. Finally, high PCE can be obtained for all-polymer solar cell devices prepared in either halogen-containing or green solvent conditions, suggesting that the introduction of backbone asymmetric building blocks is an effective method to invent high-performance, green solvent processable fused ring n-type polymers.

The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A condensed ring n-type polymer with asymmetric framework is characterized in that the structural general formula is shown as formula I:

wherein, R in the structural formula of the D1A' D2 unit ₁ 、R ₂ 、R ₃ And R ₄ Each independently selected from H, halogen, straight chain or branched chain alkyl or alkoxy or alkylthio group with 1-50 carbon atoms or alkyl substituted aryl; the alkyl in the alkyl-substituted aryl is a straight chain or branched chain alkyl with 1-50 carbon atoms, and the aryl is a benzene ring or a thiophene ring; the halogen is F, Cl or I; in the structural formula, X and Y independently represent O, S or Se atom; the dotted line in the structural formula D1A' D2 represents the attachment site to the A unit;

dotted line in the A unit structural formula: (ii) denotes the attachment site of the A unit to the D1A' D2 unit; ② represents a linking site of the A unit and the copolymerization unit 2;

2. A backbone-asymmetric fused ring n-type polymer as in claim 1, wherein one of said interpolymerized units 1 is represented by formula iii:

wherein R in the formula III ₅ 、R ₆ 、R ₇ Each independently selected from H, halogen, straight chain or branched chain alkyl or alkoxy or alkylthio group with 1-50 carbon atoms or alkyl substituted aryl; the alkyl in the alkyl-substituted aryl is a straight chain or branched chain alkyl with 1-50 carbon atoms, and the aryl is a benzene ring or a thiophene ring; the halogen is F, Cl or I; in the structural formula, X and Y independently represent O, S or Se atom; the dotted line in said formula III indicates the attachment site to the copolymerizing unit 2.

3. The polymer of claim 1 or 2, wherein one of the polymers of formula i has the structure of formula iv:

4. A process for preparing a polymer of formula i according to any one of claims 1 to 3, comprising the steps of:

and (3) under the inert gas atmosphere, mixing the monomer of the copolymerization unit 1 and the monomer of the copolymerization unit 2 in a reaction solvent, carrying out polymerization reaction under the catalysis of a catalyst, and purifying to obtain the copolymer.

5. The method according to claim 4, wherein the addition amount of the comonomer unit 1 monomer and the comonomer unit 2 monomer is such that: the molar ratio is 1: 1.

6. The method of claim 4, wherein the reaction solvent comprises at least one of toluene, o-xylene, or chlorobenzene.

7. The method of claim 4, wherein the catalyst comprises a palladium catalyst.

8. The method according to claim 4, wherein the polymerization reaction is carried out at a reaction temperature of 100 to 120 ℃, a reaction time of 12 to 72 hours, and a stirring speed of 500 to 1000 rpm.

9. The method of claim 4, wherein the mixing is performed by physical blending; the purification mode comprises more than one of filtration, column chromatography and Soxhlet extraction dialysis.

10. Use of the backbone asymmetric fused ring n-type polymer according to any of claims 1-4 as acceptor material in organic solar cells.