CN111100145B

CN111100145B - Asymmetric aromatic heterocyclic thiophene diketone organic solar cell donor material, and preparation method and application thereof

Info

Publication number: CN111100145B
Application number: CN201911316309.0A
Authority: CN
Inventors: 高跃岳; 谭付瑞; 刘荣; 董琛; 张伟风
Original assignee: Henan University
Current assignee: Henan University
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2020-10-27
Anticipated expiration: 2039-12-19
Also published as: CN111100145A

Abstract

The application discloses an asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material, a preparation method and application thereof, wherein the chemical structural formula of the polymer is as follows:

R₁，R₂，R₃the material is C4-C16 saturated alkane, X is O or S, Y is O or S, A is one of O, S and Se, a Z-containing ring is thiophene, furan, a benzene ring or a naphthalene ring, and n = 6-30. In addition, the series of polymers designed and synthesized by the invention have higher conjugated planes and moderate HOMO energy levels and LUMO energy levels. Asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material and PC₇₁The polymer solar cell prepared by BM blending has the advantages that the cell shows better photovoltaic performance based on the thiophene benzofuran-thiophene diketothiophene polymer PTBF-asy-BDD without any treatment, and the corresponding cell preparation has no harsh requirements on operation, so that the polymer solar cell is suitable for wide popularization.

Description

Asymmetric aromatic heterocyclic thiophene diketone organic solar cell donor material, and preparation method and application thereof

Technical Field

The invention belongs to the field of polymer synthesis and application thereof, and particularly relates to an asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material, and a preparation method and application thereof.

Background

The Bulk Polymer Solar Cells (B-PSCs) not only have the characteristics of light weight, good flexibility and low cost, but also can be prepared by various methods such as a spin coating method, ink-jet printing, screen printing, roll printing and the like. Therefore, the polymer solar cell is considered to be an effective means for realizing photoelectric conversion in a smart window, a flexible substrate and a special environment in a large-scale laying manner in the future. The bulk heterojunction polymer solar cell is a photovoltaic device generally constructed by sandwiching a photosensitive material between two electrodes, wherein the photosensitive material of the device is an active layer mainly constructed by blending a p-type organic semiconductor material and an n-type organic semiconductor material. In general, p-type organic semiconductor materials mainly include small molecules and polymers, and the development of new polymers has been an important driving role in the development of polymer solar cells.

The mainstream polymer is a conjugated polymer containing a Donor-Acceptor unit (Donor-Acceptor) in a molecular skeleton, wherein the Donor unit and the Acceptor unit have large selectivity space, so that researchers have successfully synthesized tens of thousands of novel polymers. Among the acceptor units, the thienothiophene diketone serving as a high-efficiency acceptor unit not only has a simple, symmetrical and polar structure, but also has easily-modified photophysical properties, and the corresponding polymer shows excellent photovoltaic performance. When the thienothiophene diketone and other donor units are copolymerized, a polymer can form a larger pi conjugated system, so that electron delocalization is facilitated, and meanwhile, the thienothiophene diketone also has a stronger electron-withdrawing effect, so that the HOMO and LUMO energy levels of corresponding polymers can be reduced, the open-circuit voltage of a cell can be improved, the energy conversion efficiency of the polymer solar cell can be improved, and the problem that the efficiency of corresponding cell devices is lower is solved.

So far, the photoelectric conversion efficiency of the polymer solar cell based on thienothiophene diketone exceeds 12%, but most of the reported thienothiophene diketone-based polymers are based on a polymer system with a symmetrical molecular structure, the carrier transmission rate of the polymer and the corresponding device is low, the device carrier recombination is caused to a certain extent, and the short-circuit current and the filling factor of the cell are reduced. Compared with a molecular structure with a symmetrical structure, the asymmetric molecular structure is introduced into polymer molecules, so that dipole moment can be introduced, charge transmission in the polymer molecules is enhanced, and the asymmetric polymer always has higher number average molar mass, so that the capability of absorbing sunlight photons can be enhanced, and the short-circuit current of the cell can be promoted. So far, although there have been some studies on asymmetric thienothiophene dione based polymers, the related studies have mainly focused on asymmetric studies of donor fragments, and few studies on asymmetric structures of thienothiophene dione acceptor units. Therefore, the development of the polymer research based on the asymmetric thienothiophene diketone can not only provide a research foundation for the research of the high-efficiency polymer based on the asymmetric thienothiophene diketone, but also further enrich the polymer donor material system, and has important research significance.

Disclosure of Invention

The invention aims to provide an asymmetric aromatic heterocyclic thiophene diketone organic solar cell donor material, a preparation method and application thereof.

The structural formula of the donor material of the asymmetric aromatic heterocyclic thiophene diketone organic solar cell prepared by the invention is as follows:

，R₁，R₂，R₃is C4-C16 saturated alkane, X is O or S, Y is O or S, A is one of O, S and Se, the ring containing Z is thiophene, furan, benzene ring or naphthalene ring, n =6-30, and R is₁≠R₂。

A preparation method of asymmetric aromatic heterocyclic thiophene diketone organic solar cell donor materials comprises the following steps:

(1) synthesis of Donor units reference (BDT Synthesis reference)Macromolecules, 2008,416012 reference for synthesis of TBFDyes Pigments., 2017,146543 synthetic reference to BDFSolar RRL,2018,2, 1800186)。

(2) Dissolving the compound 1 in glacial acetic acid, dropwise adding an acetic acid solution of liquid bromine in an ice water bath, absorbing tail gas generated in the dropwise adding process by a tail gas absorption device, gradually heating the mixture until reflux is achieved after the dropwise adding is finished, stirring and reacting the mixture to be complete, removing the solvent after the mixture is cooled to room temperature, dropwise adding a saturated sodium thiosulfate aqueous solution into the remaining mixture until the system does not generate bubbles any more and the system pH =7, filtering, washing a filter cake, and recrystallizing to obtain a compound 2;

(3) dissolving the compound 2 in dichloromethane, injecting 2-3 drops of DMF (dimethyl formamide) by using an injector, placing the mixture in an ice bath under a protective atmosphere, stirring for 20-40 mins, dropwise adding oxalyl chloride, moving the mixture to room temperature after dropwise adding is finished, stirring for reacting completely, removing the solvent and excessive oxalyl chloride, and directly using the crude product 2, 5-dibromo-3, 4-thiophene diformyl chloride in the next step;

dissolving 2, 5-dibromo-3, 4-thiophene diformyl chloride in anhydrous dichloromethane, adding a compound 3, placing the mixture in an ice bath, stirring for 20-40 mins, adding anhydrous aluminum trichloride in batches, stirring for 10-30 mins in the ice water bath after the addition is finished, moving to room temperature, stirring completely, pouring the mixture into ice hydrochloric acid, extracting with chloroform, drying, filtering, removing the solvent under reduced pressure, and separating a crude product by column chromatography to obtain a compound 4;

(4) dissolving the compound 10 and the compound 4 in a mixed solvent of chlorobenzene and DMF (the volume ratio of the chlorobenzene to the DMF is 9: 1), adding a catalyst of tetrakis (triphenylphosphine) palladium, heating to react completely, and carrying out post-treatment to obtain the target polymer.

Further, the tail gas absorption device in the step (2) is a saturated aqueous solution of sodium hydroxide; the stirring reaction time is 12-16 h.

Further, the syringe volume of step (3) is 2 mL.

Further, the molar ratio of the compound 1 to the liquid bromine in the step (2) is 1 (6-6.1); the molar ratio of the compound 2 to oxalyl chloride in the step (3) is 1 (10-10.5); the molar ratio of the compound 2, the compound 3 and the aluminum trichloride is 1 (1.1-1.2) to 4.2-5; in the step (5), the molar ratio of the compound 4 to the compound 10 to the tetrakis (triphenylphosphine) palladium is 1:1 (0.03-0.05). When the compound 4 is prepared in the step (3), the volume ratio of the petroleum ether and the dichloromethane in the eluent is 7: 1-5: 1.

Furthermore, chlorobenzene and N, N-dimethylformamide in the step (5) are ultra-dry anhydrous reagents, and the water content is less than 10 ppm. Particularly, the post-treatment of the target polymer in the step (5) is to cool the mixed solution to room temperature, add the mixed solution into methanol and stir the mixed solution for 0.5 to 5 hours, then filter and collect the solid, quickly pass through a silica gel column, place the solid in a Soxhlet extractor, sequentially extract the solid with methanol, acetone, n-hexane and chloroform for 2 to 6 hours respectively, finally remove most of the solvent from the chloroform solution through a rotary evaporator, add the residual viscous mixture into methanol again for precipitation, filter and dry the viscous mixture to obtain the target polymer.

The method for preparing the polymer solar cell by using the asymmetric aromatic heterocyclic thiophene diketone organic solar cell donor material comprises the following steps:

(1) cleaning the ITO conductive glass;

(2) blow-drying the ITO with nitrogen flow, and then placing the ITO in an argon plasma cleaning instrument for plasma treatment;

(3) preparing a PEDOT (PSS (poly 3, 4-ethylenedioxythiophene: polystyrene sulfonate)) hole transport layer;

(4) asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material and PC₇₁BM blending and dissolving in an organic solvent, then stirring for at least 6.0 h, and spin-coating on a PEDOT (PSS) hole transport layer to prepare an optical active layer;

(5) spin-coating methanol solution of PFN on the active layer to obtain PFN electron transport layer;

(6) a photocathode was prepared by thermal evaporation of metallic Al on the PFN electron transport layer.

The donor material of the asymmetric aromatic heterocyclic thiophene diketone organic solar cell is

n=7、

n=17、

n=25。

Asymmetric aromatic heterocyclic thiophene diketone organic solar cell donor material and PC₇₁The mass ratio of BM is 1 (1-2), the organic solvent is chloroform, and the concentration of the asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material in chloroform is 5-15 mg/mL.

According to the polymer solar cell prepared by the preparation method, the thickness of a hole transmission layer of the polymer solar cell is 40-50nm, the thickness of an active layer is 90-120 nm, the thickness of an electron transmission layer is 8-10nm, and the thickness of a photocathode is 100-110 nm.

The invention provides a preparation method of an asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material and application thereof in the field of polymer solar cells.

The technical scheme of the invention at least has the following beneficial effects:

(1) the invention prepares a series of novel asymmetric thienothiophene five-membered fused ring diketone acceptor units, and particularly takes the performance of the asymmetric thienothiophene diketone acceptor units as the best;

(2) the invention prepares a series of D-A type medium band gap polymers based on asymmetric thienothiophene diketone;

(3) the series of D-A type medium band gap polymers based on the asymmetric thienothiophene diketone have better electrochemical performance;

(4) the D-A type medium band gap polymer based on the asymmetric thienothiophene diketone prepared by the invention has better photovoltaic performance.

Drawings

FIG. 1 is a schematic view of a tail gas absorption unit involved in the synthesis process of the present invention;

FIG. 2 is an asymmetric thieno five-membered fused ring diketone acceptor unit designed according to this invention;

FIG. 3 is a chemical structural formula of a cathode interface transport layer PFN of a battery device according to the present invention;

FIG. 4 is a schematic diagram of a battery according to the present invention;

FIG. 5 is a schematic diagram of the electron energy levels of various portions of a battery of the present invention;

FIG. 6 shows examples 5 to 7 of polymer solar cells prepared based on asymmetric thienothiophene diketo-based polymers according to the present inventionJ-V curve (tested by solar photoelectric test system (94043A-S), in glove box, from-0.2V to 1.2V, sweep speed of 10mV/S, delay time of 20ms, AM1.5G simulated sunlight, light intensity of 100mW/cm²）。

Detailed Description

To make the purpose, technology and advantages of the present invention clearer and more complete description of the technical solutions related to the present invention will be given below with reference to specific embodiments of the present invention, and it will be apparent to those skilled in the art that various modifications may be made without departing from the principles of the embodiments of the present invention, and these modifications are also considered as the scope of the embodiments of the present invention.

Example 1

Preparation of compound Asy-BDD:

EH stands for isopropyl.

(1) Compound 1(5g, 28.5 mmol), 60 mL glacial acetic acid were placed in a 500mL three-necked flask, and the three-necked flask was placed under an ice-water bath and stirred for 30 mins. A solution of liquid bromine in acetic acid (1mol/L, 172mL, 172mmol) was slowly added dropwise to the three-necked flask via a constant pressure dropping funnel, and after the addition, the stirring was continued for 15mins in an ice-water bath. Then slowly heating to 85 DEG^oC stirred overnight. And (3) cooling the mixture to room temperature, decompressing and spinning out most of the solvent through a rotary evaporator, adding saturated sodium thiosulfate aqueous solution into the residue, and stirring while changing the addition until the reaction does not generate gas any more and the pH of the system is close to 7. Filtering, washing a filter cake with a small amount of deionized water and absolute ethyl alcohol, placing the filter cake into the deionized water for recrystallization, filtering and drying in vacuum to obtain 8.2 g of gray needle-shaped solid 2, 5-dibromo-3, 4-thiophenedicarboxylic acid (compound 2), wherein the yield is 87.2%.¹H-NMR(400MHz, DMSO,TMS): 13.62 (s, 2H)。

(2) Compound 2(8.16g, 24.7mmol), 30 mL of anhydrous dichloromethane, 05mL of DMMF was placed in a 250mL two-necked flask and protected with nitrogen, and then the two-necked flask was placed in an ice-water bath and stirred for 30 mins. Oxalyl chloride (167mL, 250mmol) was slowly added dropwise to the two-necked flask via a constant pressure dropping funnel, and after the addition was completed, the ice-water bath was stirred for a further 15mins, then allowed to warm to room temperature and stirred overnight. The solvent was spun off rapidly by rotary evaporator and 60 mL of anhydrous dichloromethane, 2-butyl-5-isopropylthiophene (compound 3a, 7.47g, 29.6mmol), nitrogen protected, was added again rapidly and stirred for 30mins under ice-water bath. Anhydrous aluminum trichloride (16.46g, 123.5mmol) was added in four portions at a rapid rate, and stirring was continued for 30mins in an ice-water bath after the addition was completed. The two-necked flask was then allowed to warm to room temperature and stirred overnight. The mixture was poured slowly into ice in 1-1.5 mol/L hydrochloric acid and extracted with 5X 60 mL chloroform, the combined organic phases were dried over anhydrous magnesium sulfate, filtered and the solvent was removed by rotary evaporation. The obtained crude product is separated by column chromatography (petroleum ether/dichloromethane = 7-5: 1, volume ratio), and finally dried in vacuum to obtain 6.49 g of light yellow solid asymmetric thienothiophene diketone (Asy-BDD), wherein the yield is 48.1%.¹H-NMR(400MHz, CDCl₃, TMS): 3.31 (d,J=6.8Hz，2H)，2.26 (t,J=6.4Hz，2H)，1.78 (m, 1H)，1.51-1.27 (m, 12H)，0.91-0.89 (t,J=6.4Hz，9H)。

Example 2

Benzodithiophene-bistrimethyltin donor units (BDT, 0.20 mmol, 180.9 mg), asymmetric thienothiophenedione acceptor units (Asy-BDD, 0.20 mmol, 109.3 mg), tetrakis (triphenylphosphine) palladium (0.0069mmol, 8 mg) were added to a flask containing N₂In a 25.0 mL single neck flask with a protective device. Then, the vacuum pumping and nitrogen filling cycle is repeated for 3-4 times, and 9mL of anhydrous chlorobenzene and 1mL of anhydrous DMF are injected by a syringe under the protection of nitrogen. After the addition, the mixture was again evacuated and charged with nitrogen. The mixture was then heated rapidly to 120 ℃ during which time the change in viscosity of the mixture was observed. When the rotor speed in the reaction flask becomes slow, 0.1mL of 2-tributylstannane thiophene (capping agent) is injected by a syringe, and stirring is continued for 2.0 h. Tighten up0.1mL 2-bromothiophene (capping agent) was then injected with a syringe and stirring was continued for 2.0 h. After the mixture was cooled to room temperature, the mixture was slowly added to 200mL of methanol and stirred for 2.0 h. The solid was collected by filtration, dissolved in chloroform and rapidly passed through a small silica gel column (length 200 mm. times.inner diameter 20 mm; eluent chloroform), the solvent was removed from the chloroform pool by a rotary evaporator, and the residual solid was placed in a Soxhlet extractor and extracted with 50mL of methanol, 50mL of acetone, 50mL of n-hexane and 50mL of chloroform in this order for 12 hours each. Finally, the chloroform solution was evaporated under reduced pressure by a rotary evaporator to remove most of the solvent, and the remaining viscous mixture was added dropwise to 200mL of methanol to precipitate again, filtered, and dried in vacuo to give PBDT-asy-BDD (108.3 mg, 56.2%), GPC (CB) as a dark brown solid, Mn =6.4 kDa (n =7), Mw =11.6 kDa, and PDI =1.82.

Example 3

Thiophene benzofuran-bis-trimethyltin donor units (TBF, 0.20 mmol, 177.7 mg), asymmetric thienothiophene dione acceptor units (Asy-BDD, 0.20 mmol, 109.3 mg), tetrakis (triphenylphosphine) palladium (0.0087mmol, 10mg) were added to the charge N₂In a 25.0 mL single neck flask with a protective device. Then, the vacuum pumping and nitrogen filling cycle is repeated for 3-4 times, and 9mL of anhydrous chlorobenzene and 1mL of anhydrous DMF are injected by a syringe under the protection of nitrogen. After the addition, the mixture was again evacuated and charged with nitrogen. Then rapidly heating to 130 deg.C^oAnd C, observing the change of the viscosity of the mixture in the period. When the rotor speed in the reaction flask becomes slow, 0.1mL of 2-tributylstannane thiophene was injected with the syringe and stirring was continued for 2.0 h. 0.1mL 2-bromothiophene was then injected with a syringe and stirring was continued for 2.0 h. After the mixture was cooled to room temperature, the mixture was slowly added to 200mL of methanol and stirred for 2.0 h. The solid was collected by filtration, dissolved in chloroform and rapidly passed through a small silica gel column (length 200 mm. times.inner diameter 20 mm; eluent chloroform), the solvent was removed from the chloroform pool by a rotary evaporator, and the residual solid was placed in a Soxhlet extractor and extracted with 50mL of methanol, 50mL of acetone, 50mL of n-hexane and 50mL of chloroform in this order for 12 hours each. Finally, the chloroform solution is subjected to spinMost of the solvent was removed under reduced pressure by a trans-evaporator, and the remaining viscous mixture was added dropwise to 200mL of methanol to precipitate again, filtered, and dried in vacuo to give PTBF-asy-BDD (152.2 mg, 80.3%), GPC (CB) as a dark brown solid, Mn =23.6 kDa (n =25), Mw =45.1kDa, and PDI = 1.91.

Example 4

Benzodifuran-bistrimethyltin donor units (BDF, 0.20 mmol, 174.5 mg), asymmetric thienothiophenedione acceptor units (Asy-BDD, 0.20 mmol, 109.3 mg), tetrakis (triphenylphosphine) palladium (0.0078mmol, 9 mg) were added to the charge N₂In a 25.0 mL single neck flask with a protective device. Then, the vacuum and nitrogen filling cycle is repeated for 3-4 times, and 10mL of anhydrous chlorobenzene and 1mL of anhydrous DMF are injected by a syringe under the protection of nitrogen. After the addition, the mixture was again evacuated and charged with nitrogen. Then rapidly heating to 130 deg.C^oAnd C, observing the change of the viscosity of the mixture in the period. When the rotor speed in the reaction flask becomes slow, 0.1mL of 2-tributylstannane thiophene was injected with the syringe and stirring was continued for 2.0 h. 0.1mL 2-bromothiophene was then injected with a syringe and stirring was continued for 2.0 h. After the mixture was cooled to room temperature, the mixture was slowly added to 200mL of methanol and stirred for 2.0 h. The solid was collected by filtration, dissolved in chloroform and rapidly passed through a small silica gel column (length 200 mm. times.inner diameter 20 mm; eluent chloroform), the solvent was removed from the chloroform pool by a rotary evaporator, and the residual solid was placed in a Soxhlet extractor and extracted with 50mL of methanol, 50mL of acetone, 50mL of n-hexane and 50mL of chloroform in this order for 12 hours each. Finally, the chloroform solution was evaporated under reduced pressure by a rotary evaporator to remove most of the solvent, and the remaining viscous mixture was added dropwise to 200mL of methanol to precipitate again, filtered, and dried in vacuo to give PBDF-asy-BDD (115.7 mg, 62.1%), GPC (CB) Mn =11.8 kDa (n =17), Mw =21.8 kDa, and PDI =1.85 as a dark brown solid.

The following examples are the application of asymmetric aromatic heterocyclic thiophene diketo organic solar cell donor materials in polymer solar cells.

Example 5

According to the electron energy level of the donor material of the asymmetric aromatic heterocyclic thiophene diketone organic solar cell prepared by the invention, the donor material and PC are prepared₇₁And preparing a polymer solar cell by BM blending, and testing the photovoltaic performance of the device. In the preparation process of a battery device, the invention adopts asymmetric thienothiophene diketone-based polymer as a donor material, and PC₇₁BM is used as an acceptor material to prepare an active layer, ITO is used as a battery anode, PEDOT, PSS, PFN, Al and PC are used as battery electron transport layers, and the device structure is ITO/PEDOT, PSS/P-asy-BDD and PC₇₁BM/PFN/Al as shown in FIG. 4. The preparation process comprises the following steps:

1) and (3) ultrasonically cleaning the ITO conductive glass substrate (15 omega/square) with toluene, deionized water, ethanol, acetone and isopropanol for 15min respectively in sequence.

2) The ITO was blown dry with a stream of nitrogen and then treated in an argon plasma processor for 5mins (P < -92 kPa).

3) Aqueous dispersions of PEDOT: PSS (Clevious PVP AI 4083) were filtered through a 0.22 μm aqueous microfiltration membrane filter and spin-coated on a treated ITO substrate by a spin coater at 4500 rpm/s for 25 s, with a membrane thickness of about 40 nm. Then, the ITO substrate was placed at 150^oC, annealing for 15min on a hot bench. After cooling to room temperature, move into glove box (C)_O2<0.1 ppm，C_H2O<0.1 ppm)。

4) The polymer material and the receptor material are co-dissolved in chloroform according to a certain proportion, stirred at room temperature for at least 6.0 h, and then spin-coated with an active layer film on a PEDOT (polymer induced thermal plasticity) PSS (polymer induced plasticity) layer by a spin coater at a certain rotating speed.

5) An electron transport layer was prepared by spin-coating a solution of PFN (structural formula shown in FIG. 3) in methanol at 4000 rpm/s through a spin coater.

6) At 7X 10^-4Preparing photocathode by thermally evaporating metal (Al) under Pa vacuum degree, and the area of the active layer of the cell is 4.0 mm²The battery device structure is shown in fig. 4.

7) And testing the photoelectric performance of the battery device.

Taking PBDT-asy-BDD as an example, the structure of the battery device is ITO/PEDOT: PSS (40)nm)/PBDT-asy-BDD:PC₇₁BM (95nm)/PFN (8nm)/Al (100nm), wherein PBDT-asy-BDD is mixed with PC₇₁BM was dissolved in chloroform and the concentration of PBDT-asy-BDD in chloroform was 10 mg/mL. When PBDT-asy-BDD and PC₇₁BM mass ratio of 1:1.5 and device V as shown in FIG. 6 without any treatment_oc=0.858 V，J _sc=3.02mA/cm²FF =33.9%, PCE = 0.878%. The lower short circuit current exhibited by PBDT-asy-BDD based devices is due to their smaller molar mass, limiting carrier transport and photon capture; the poor filling factor is caused by the strong aggregation effect of the material, and a large self pure phase can be formed without uniformly mixing the material for the receptor.

Example 6

Taking PTBF-asy-BDD as an example, the structure of the battery device is ITO/PEDOT: PSS (40nm)/PTBF-asy-BDD: PC₇₁BM (112nm)/PFN (9nm)/Al (110nm), wherein PTBF-asy-BDD and PC₇₁BM was dissolved in chloroform and the concentration of PBDT-asy-BDD was controlled to be 11.5 mg/mL. When PTBF-asy-BDD is PC₇₁BM mass ratio of 1:1.5 and device V as shown in FIG. 6 without any treatment_oc=0.880 V，J _sc=12.15mA/cm²FF =69.8%, PCE = 7.46%. The higher open circuit voltage exhibited by PBDT-asy-BDD based devices stems from their higher HOMO levels; higher short-circuit current is derived from larger molar mass of the short-circuit current, and can efficiently promote carrier transmission and enhance the capture of photons; the better filling factor is due to the better solubility of the material, and can be possibly mixed with the PC acceptor material₇₁BM forms a uniform mixture.

Example 7

Taking PBDF-asy-BDD as an example, the structure of the battery device is ITO/PEDOT: PSS (40nm)/PBDF-asy-BDD: PC₇₁BM (106nm)/PFN (10nm)/Al (105nm), wherein PBDF-asy-BDD is mixed with PC₇₁BM was dissolved in chloroform and the concentration of PBDF-asy-BDD was controlled to 10 mg/mL. When PBDF-asy-BDD is PC₇₁BM mass ratio of 1:1.5 and device V as shown in FIG. 6 without any treatment_oc=0.910 V，J _sc=11.88mA/cm²FF =50.8%, PCE = 5.49%. PBDT-asy-BDD-based devices show betterThe high open circuit voltage is derived from its higher HOMO level; higher short-circuit current is derived from larger molar mass of the short-circuit current, and can efficiently promote carrier transmission and enhance the capture of photons; the poor filling factor is derived from the stronger conjugation effect, forms stronger self-aggregation domain and is difficult to receive the material PC₇₁The BM forms uniform mixing, and increases the probability of carrier recombination to a certain extent.

The present invention includes, but is not limited to, the above embodiments, and any equivalent substitutions or partial modifications made under the principle of the spirit of the present invention are considered to be within the scope of the present invention.

Claims

1. An asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material is characterized in that: the asymmetric aromatic heterocyclic thiophene diketone organic solar cell donor material has the following structural formula:

，R₁，R₂，R₃is C4-C16 saturated alkane, R₁≠R₂X is O or S, Y is O or S, A is one of O, S and Se, a Z-containing ring is thiophene, and n = 17-30.

2. The preparation method of the donor material of the asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell according to claim 1 is characterized in that the synthetic route is as follows:

(1) dissolving the compound 1 in glacial acetic acid, dropwise adding an acetic acid solution of liquid bromine in an ice water bath, absorbing tail gas generated in the dropwise adding process by an absorption device, heating the mixture to reflux after the dropwise adding is finished, stirring and reacting completely, removing the solvent after the mixture is cooled to room temperature, dropwise adding a saturated sodium thiosulfate aqueous solution into the rest mixture until the system does not generate bubbles any more, filtering, washing a filter cake, and recrystallizing to obtain a compound 2;

(2) dissolving a compound 2 in dichloromethane, injecting 2-3 drops of DMF (dimethyl formamide), placing the mixture in an ice bath under a protective atmosphere, stirring for 20-40 mins, dropwise adding oxalyl chloride, moving the mixture to room temperature after dropwise adding, stirring and reacting completely, removing a solvent and unreacted oxalyl chloride, dissolving a crude product in anhydrous dichloromethane, adding a compound 3, placing the mixture in an ice bath, stirring for 20-40 mins, adding anhydrous aluminum trichloride in batches, stirring for 10-30 mins in an ice water bath after adding, moving to room temperature, stirring completely, pouring the mixture into ice hydrochloric acid, extracting with chloroform, drying, filtering, removing the solvent under reduced pressure, and separating the crude product by column chromatography to obtain a compound 4;

(3) dissolving the compound 10 and the compound 4 in a mixed solvent of chlorobenzene and DMF, adding a catalyst of tetrakis (triphenylphosphine) palladium, heating to react completely, and carrying out post-treatment to obtain the target polymer.

3. The preparation method of the donor material of the asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell according to claim 2, characterized in that the molar ratio of the compound 1 to the liquid bromine in the step (1) is 1 (6-6.1); the molar ratio of the compound 2 to oxalyl chloride in the step (2) is 1 (10-10.5); the molar ratio of the compound 2, the compound 3 and the aluminum trichloride is 1 (1.1-1.2) to 4.2-5; the molar ratio of the compound 4, the compound 10 and the tetrakis (triphenylphosphine) palladium in the step (4) is 1:1 (0.03-0.05).

4. A method for preparing a polymer solar cell by using the donor material of the asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell as described in claim 1, which is characterized by comprising the following steps:

(1) cleaning the conductive glass;

(2) blowing the conductive glass by using nitrogen flow, and then placing the conductive glass in an argon plasma cleaning instrument for plasma treatment;

(3) spin-coating PEDOT, namely a PSS hole transport layer;

(4) asymmetric aromatic heterocyclic ringDiketothiophene organic solar cell donor material and PC₇₁BM blending and dissolving in an organic solvent, then stirring for at least 6.0 h, and spin-coating on a PEDOT (PSS) hole transport layer to prepare an optical active layer;

5. The method for preparing the polymer solar cell according to claim 4, wherein the asymmetric aromatic heterocyclic thiophene diketo organic solar cell donor material is

n=17、

n =25, and EH represents isopropyl group in the formula.

6. The method for preparing a polymer solar cell according to claim 4 or 5, wherein the asymmetric aromatic heterocyclic thiophene diketo organic solar cell donor material is mixed with PC₇₁The mass ratio of BM is 1 (1-2), the organic solvent is chloroform, and the concentration of the asymmetric aromatic heterocyclic thiophene diketone-based organic solar cell donor material in chloroform is 5-15 mg/mL.

7. The polymer solar cell prepared by the preparation method of claim 4 or 5, wherein the thickness of the hole transport layer of the polymer solar cell is 40-50nm, the thickness of the active layer is 90-120 nm, the thickness of the electron transport layer is 8-10nm, and the thickness of the photocathode is 100-110 nm.

8. The use of the asymmetric aromatic heterocyclic thiophene diketo organic solar cell donor material according to claim 1 in the field of organic solar cells.