CN106188033B - D-A type micromolecular compound and its preparation method and application - Google Patents

Abstract

The present invention provides D-A type small molecule compound having the structure shown in formula I, formula II or formula III, with phenothiazine as electron-donating group, with malononitrile, 2-ethylhexyl cyanoacetate or 2‑ethylrhodanine as an electron-withdrawing group. In the present invention, there is a phenomenon of internal charge transfer in the small molecules of the D-A structure, which helps to improve the absorption performance of the material; the electron-withdrawing group can adjust the energy level of the small molecule combination of the material to obtain good performance Narrow-band photovoltaic materials. Moreover, phenothiazine itself has moderate steric deformability and the introduction of side chain alkyl makes it have a non-planar geometric configuration. The N and S atoms on the phenothiazine unit help to enhance the electron donation of the main chain of the molecule. ability. Experimental results show that the solar cell device including the D-A type small molecule compound layer provided by the present invention has a relatively high photoelectric energy conversion efficiency of about 2.8%.

Description

D-A type small molecular compound and its preparation method and application

technical field

The invention relates to the technical field of solar cells, in particular to a D-A type small molecule compound and its preparation method and application.

Background technique

Organic solar cells are another new type of non-fossil energy application after inorganic solar cells, which is very in line with the development requirements of clean and pollution-free renewable energy. Organic solar cells are thinner, more flexible, and cheaper, and come in a wider variety of colors, shapes, and transparency. There are two types of organic solar cell materials: small molecules and polymers. Currently, the blend system of polymer donors and fullerene acceptors is the most efficient. However, the molecular structure, molecular weight, and purity of polymers are uncertain, which will cause differences in the properties of different batches of materials, which may lead to batch instability in industrial production in the future. Compared with polymer materials, small organic molecule solar cell materials have a definite molecular structure and molecular weight, and are relatively easy to separate and purify, have high purity, and have good batch stability during the preparation process. Moreover, organic small molecule solar cell materials have the advantages of relatively simple preparation process, low cost, and easy large-scale production, and have been favored by people in recent years.

Small organic molecules have the following advantages: definite structure and molecular weight, high carrier mobility, simple purification process and good repeatability, etc. Based on these advantages of small molecule materials, more and more researchers Set your sights on it. So far, the photovoltaic performance of small-molecule solar cells has been greatly improved, especially the photoelectric conversion efficiency of the device has been greatly improved, but the matching problem between the absorption spectrum of small-molecule materials and the solar spectrum is still a constraint for organic small-molecule materials. Key factor for improved efficiency of molecular solar cells.

Contents of the invention

The object of the present invention is to provide a D-A type small molecule compound and its preparation method and application. The solar cell prepared from the small molecule compound provided by the present invention has higher efficiency.

The present invention provides D-A type small molecular compounds having the structure shown in formula I, formula II or formula III:

The present invention provides a preparation method for the D-A type small molecule compound described in the above technical scheme, comprising the following steps:

Under a protective gas atmosphere, the compound having the structure shown in formula IV, the electron-withdrawing monomer and the catalyst are reacted in an organic solvent system to obtain the D-A small molecule compound with the structure shown in formula I, formula II or formula III;

The electron-withdrawing monomer is malononitrile, 2-ethylhexyl cyanoacetate or 3-ethylrhodanine.

Preferably, when the electron-withdrawing monomer is malononitrile, the catalyst is L-alanine.

Preferably, when the electron-withdrawing monomer is 2-ethylhexyl cyanoacetate, the catalyst is a tertiary amine.

Preferably, when the electron-withdrawing monomer is 3-ethylrhodanine, the catalyst is piperidine.

Preferably, the organic solvent is a chlorinated alkane compound.

Preferably, the molar ratio of the compound represented by the formula IV to the electron-withdrawing monomer is 1:(2-30).

Preferably, after the reaction, the method further includes: performing column chromatography on the reaction product obtained in the reaction.

Preferably, before the column chromatography, it also includes: extracting the reaction solution of the reaction.

The present invention also provides the application of the D-A type small molecule compound described in the above technical solution or the D-A type small molecule compound prepared by the preparation method described in the above technical solution in solar cells.

The present invention also provides a solar cell device, comprising an ITO glass layer, a ZnO layer disposed on the ITO glass layer, a DA type small molecule compound layer disposed on the ZnO layer, and a DA type small molecule compound layer disposed on the DA type small A _C60 electron transport layer on the molecular compound layer, a cathode buffer layer disposed on the _C60 electron transport layer, and an Ag electrode layer disposed on the cathode buffer layer;

The D-A type small molecule compound is the D-A type small molecule compound described in the above technical scheme or the D-A type small molecule compound prepared by the preparation method described in the above technical scheme.

The present invention provides D-A type small molecular compounds having structures shown in formula I, formula II or formula III, with phenothiazine as electron donating group, malononitrile, 2-ethylhexyl cyanoacetate or 2 - Ethyl rhodanine as electron withdrawing group. In the present invention, there is a phenomenon of internal charge transfer in the small molecule of the D-A structure, which helps to improve the absorption performance of the material; the electron-withdrawing group can adjust the energy level of the small molecule combination of the material to obtain a narrow band with good performance. Department of photovoltaic materials. Moreover, phenothiazine itself has moderate steric deformability and the introduction of side chain alkyl makes it have a non-planar geometric configuration. The N and S atoms on the phenothiazine unit help to enhance the electron donation of the main chain of the molecule. ability. In addition, the small molecular compound provided by the present invention also has the following characteristics: (1) There are many active atoms on the ring, and the structure of the molecule can be modified by introducing multiple functional groups (2) The transfer ability of electrons is very strong (3) The formed positron Ions are relatively stable (4) thermal stability and chemical stability are high. Experimental results show that the solar cell device including the D-A type small molecule compound layer provided by the invention has a relatively high photoelectric energy conversion efficiency of about 2.8%.

Description of drawings

FIG. 1 is a schematic structural diagram of a solar cell device provided by Embodiment 4 of the present invention.

Detailed ways

The present invention provides D-A type small molecular compounds having the structure shown in formula I, formula II or formula III:

The present invention uses phenothiazine as an electron-donating unit, and 2-ethylhexyl cyanoacetate, malononitrile or 3-ethylrhodanine as an electron-withdrawing monomer to provide a compound with formula I, formula II or formula The D-A small molecular compound of the structure shown in III, wherein the phenothiazine structure skeleton has moderate steric deformability and the introduction of side chain alkyl makes it a non-planar geometric configuration, and the N on the phenothiazine unit And S atoms help to enhance the electron-donating ability of the main chain of the molecule. In addition, the D-A type small molecular compound provided by the present invention also has the following characteristics: there are many active atoms on the ring, and the molecular structure can be modified by introducing multiple functional groups; the electron transfer ability is strong; the positive ion formed is relatively stable; thermal stability and High chemical stability.

The present invention also provides a preparation method for the D-A type small molecule compound described in the above technical scheme, comprising the following steps:

Under a protective gas atmosphere, the compound having the structure shown in formula IV, the electron-withdrawing monomer and the catalyst are reacted in an organic solvent system to obtain the D-A small molecule compound with the structure shown in formula I, formula II or formula III;

The electron-withdrawing monomer is malononitrile, 2-ethylhexyl cyanoacetate or 3-ethylrhodanine.

In the present invention, the compound having the structure shown in formula IV, the electron-withdrawing monomer and the catalyst are reacted in an organic solvent system under a protective gas atmosphere to obtain the D-A type small molecule compound described in the above technical scheme. In the present invention, when the electron-withdrawing monomer is malononitrile, the prepared D-A type small molecular compound has the structure shown in formula I; when the electron-withdrawing monomer is 2-ethylhexyl cyanoacetic acid In the case of ester, the prepared D-A small molecular compound has the structure shown in formula II; when the electron-withdrawing monomer is 3-ethyl rhodanine, the prepared D-A small molecular compound has the structure shown in formula III.

The present invention has no special limitation on the type of the protective gas, and an inert gas well known to those skilled in the art can be used, such as a rare gas. In an embodiment of the present invention, the protective gas may specifically be argon.

In the present invention, there is no special limitation on the source of the compound having the structure shown in Formula IV, and the technical solution for obtaining the compound having the structure shown in Formula IV can be adopted that is well known to those skilled in the art. In the present invention, the compound having the structure shown in formula IV is preferably obtained according to the following preparation method:

(1) Add 1-bromohexadecane dropwise to a mixture of phenothiazine, dimethyl sulfoxide and sodium hydroxide under a protective gas atmosphere, and react at room temperature for 20 to 28 hours to obtain compound 1;

(2) Under a protective gas atmosphere, sequentially add phosphorus oxychloride and 1,2-dichloroethane solution of compound 1 dropwise into dimethylformamide, heat to 90-100°C for 40-55 hours to obtain Compound 2;

(3) Under a protective gas atmosphere, mix methanol, compound 2 and 2-thiophene acetonitrile, add catalyst potassium tert-butoxide, and heat to 45-55°C for 10-14 hours to obtain compound 3;

(4) Under a protective gas atmosphere, sequentially add phosphorus oxychloride and 1,2-dichloroethane solution of compound 3 dropwise into dimethylformamide, heat to 90-100°C for 40-55 hours to obtain The compound having the structure shown in formula IV.

The present invention prepares the compound with the structure shown in formula IV under the protective gas atmosphere. In the present invention, there is no special limitation on the type of the protective gas, and an inert gas well known to those skilled in the art can be used, such as a rare gas. In the present invention, the protective gas can specifically be argon.

In the present invention, under a protective gas atmosphere, 1-bromohexadecane is added dropwise to a mixture of phenothiazine, dimethyl sulfoxide and sodium hydroxide, and reacted at room temperature for 20-28 hours to obtain compound 1. In the present invention, the molar ratio of the phenothiazine, dimethyl sulfoxide, sodium hydroxide and 1-bromohexadecane is preferably 1: (50-60): (1.8-2.5): (1.4- 1.8). In the present invention, it is preferred to mix phenothiazine, dimethyl sulfoxide and sodium hydroxide, stir the resulting mixture at room temperature for 25-35 minutes, and then add 1-bromohexadecane dropwise under a protective gas atmosphere. The present invention has no special limitation on the method and rate of the dripping, and the technical solution of dripping liquid materials well known to those skilled in the art can be adopted. In the present invention, preferably, the 1-bromohexadecane is added dropwise to the mixture of phenothiazine, dimethyl sulfoxide and sodium hydroxide.

In the present invention, after reacting at room temperature for 20-28 hours, the obtained product is preferably post-treated to obtain compound 1. In the present invention, the post-processing preferably includes the following steps:

After the reaction was over, dimethyl sulfoxide was distilled off under reduced pressure, the resulting material was extracted with CH ₂ Cl ₂ , the organic layer was dried over anhydrous Na ₂ SO ₄ , filtered, and the solvent was removed by distillation under reduced pressure, and the obtained crude product was used Compound 1 was obtained as yellow oil after purification by column chromatography (silica gel, petroleum ether).

In the present invention, under the protective gas atmosphere, phosphorus oxychloride and 1,2-dichloroethane solution of compound 1 are sequentially added dropwise to dimethylformamide, and heated to 90-100°C for 40-55 hours to obtain the compound 2. In the present invention, the molar ratio of compound 1, 1,2-dichloroethane, dimethylformamide and phosphorus oxychloride is preferably 1:(20-24):(23-26):(15 ~20), more preferably 1:(21~23):(24~25):(16~18). In the present invention, under the protection of argon, phosphorus oxychloride and the 1,2-dichloroethane solution of compound 1 are sequentially added dropwise to dimethylformamide cooled in an ice bath. The present invention has no special limitation on the method and rate of the dripping, and the technical solution of dripping liquid materials well known to those skilled in the art can be adopted. In the present invention, the drop rate of phosphorus oxychloride is preferably 0.5-0.6 mL/min; the dropwise addition of the 1,2-dichloroethane solution of compound 1 is preferably dropwise.

In the present invention, after reacting at 90-100° C. for 40-55 hours, the obtained product is preferably post-treated to obtain compound 2. In the present invention, the post-processing preferably includes the following steps:

Cool to room temperature after the reaction, pour into ice water, adjust the pH of the reactant to 6-7 with saturated sodium hydroxide solution, then extract the obtained material with CH ₂ Cl ₂ , and dry the organic layer with anhydrous Na ₂ SO ₄ , The solvent was distilled off under reduced pressure, and the obtained crude product was purified by column chromatography (silica gel, the volume ratio of CH ₂ Cl ₂ and n-hexane was 3:1) to obtain compound 2.

In the present invention, methanol, compound 2 and 2-thiophene acetonitrile are mixed under a protective gas atmosphere, catalyst potassium tert-butoxide is added, heated to 45-55° C. for 10-14 hours, and compound 3 is obtained. In the present invention, the molar ratio of the compound 2, 2-thiophene acetonitrile and methanol is preferably 1:(2~3):(250~260), more preferably 1:(2~3):(253~257 ). In the present invention, there is no special limitation on the dosage of the catalyst potassium tert-butoxide, and a catalytic amount known to those skilled in the art can be used.

In the present invention, after reacting at 45-55°C for 10-14 hours, the obtained product is preferably post-treated to obtain compound 3. In the present invention, the post-processing preferably includes the following steps:

After the reaction was completed, it was cooled to room temperature, and the solvent was spin-dried, and the obtained crude product was purified by column chromatography (silica gel, CH ₂ Cl ₂ ) to obtain compound 3 as a red solid.

In the present invention, under the protective gas atmosphere, phosphorus oxychloride and the 1,2-dichloroethane solution of compound 3 are sequentially added dropwise to dimethylformamide, heated to 90-100° C. for 40-55 hours to obtain the obtained Describe the compound with the structure shown in formula IV. In the present invention, the molar ratio of compound 3, 1,2-dichloroethane, dimethylformamide and phosphorus oxychloride is preferably 1: (30-34): (26-30): (29 ~33), more preferably 1:(31~33):(27~28):(30~32).

In the present invention, under the protection of argon, phosphorus oxychloride and compound 3 in 1,2-dichloroethane are sequentially added dropwise to dimethylformamide cooled in an ice bath. The present invention has no special limitation on the method and rate of the dripping, and the technical solution of dripping liquid materials well known to those skilled in the art can be adopted. In the present invention, the dropping rate of phosphorus oxychloride is preferably 0.15-0.18 mL/min; the dropping method of the 1,2-dichloroethane solution of compound 3 is preferably dropwise.

In the present invention, after reacting at 90-100° C. for 40-55 hours, the obtained product is preferably post-treated to obtain the compound having the structure shown in formula IV. In the present invention, the post-processing preferably includes the following steps:

Cool to room temperature after the reaction, pour into ice water, adjust the pH of the reaction solution to 6-7 with saturated sodium hydroxide solution, then extract the obtained material with CH ₂ Cl ₂ , dry the organic layer with anhydrous Na ₂ SO ₄ , The solvent was distilled off under reduced pressure, and the obtained crude product was purified by column chromatography (silica gel, CH ₂ Cl ₂ ) to obtain a red solid, which was the compound having the structure shown in Formula IV.

In the present invention, different electron-withdrawing monomers correspond to different catalyst systems; when the electron-withdrawing monomer is malononitrile, the catalyst is preferably L-alanine. In an embodiment of the present invention, when L-alanine is used as a catalyst, the ethanol solution of L-alanine is preferably used; in the present invention, the mass concentration of the ethanol solution of L-alanine is preferably 1mg /mL～5mg/mL, more preferably 2mg/mL～4mg/mL, most preferably 3.33mg/mL. In the present invention, the ethanol is preferably absolute ethanol.

When the catalyst is preferably L-alanine, in the present invention, the ethanol solution of L-alanine is preferably added dropwise to the organic solvent system including the compound having the structure shown in formula IV and the electron-withdrawing monomer. The present invention has no special limitation on the method and rate of the dripping, and the technical solution of dripping liquid materials well known to those skilled in the art can be adopted. In the embodiment of the present invention, it is preferable to drop the ethanol solution of L-alanine into the organic solvent system including the compound having the structure shown in formula IV and the electron-withdrawing monomer.

In the present invention, the mass ratio of the malononitrile to the catalyst is preferably (2-5):1, more preferably 3.6:1.

In the invention, when the electron-withdrawing monomer is 2-ethylhexyl cyanoacetate, the catalyst is preferably a tertiary amine, more preferably triethylamine. When the catalyst is preferably a tertiary amine, there is no special limitation on the amount of the catalyst used in the present invention, and a catalytic amount known to those skilled in the art can be used. When the electron-withdrawing monomer is 2-ethylhexyl cyanoacetate and the catalyst is a tertiary amine, the present invention has the compound, electron-withdrawing monomer, catalyst and organic solvent with the structure shown in formula IV There is no special limitation on the order of adding the materials, and any order of material mixing well known to those skilled in the art can be adopted.

In the present invention, when the electron-withdrawing monomer is 2-ethylrhotanine, the catalyst is preferably piperidine. When the catalyst is preferably piperidine, there is no special limitation on the amount of the catalyst used in the present invention, and a catalytic amount known to those skilled in the art can be used. When the electron-withdrawing monomer is 2-ethylrhodanine and the catalyst is piperidine, the present invention is to the order of adding the compound having the structure shown in formula IV, the electron-withdrawing monomer, the catalyst and the organic solvent There is no special limitation, and any sequence of material mixing known to those skilled in the art can be used.

In the present invention, the molar ratio of the compound having the structure represented by formula IV to the electron-withdrawing monomer is preferably 1:(2-30), more preferably 1:(3-25). Specifically, when the electron-withdrawing monomer is malononitrile, the molar ratio of the compound having the structure shown in formula IV to malononitrile is preferably 1:(2-5), more preferably 1:(3 ~4); when the electron-withdrawing monomer is 2-ethylhexyl cyanoacetate, the molar ratio of the compound having the structure shown in formula IV to 2-ethylhexyl cyanoacetate is preferably 1:(15-30), more preferably 1:(20-25), most preferably 1:24; when the electron-withdrawing monomer is 2-ethyl rhodanine, the The molar ratio of the compound of the structure to 2-ethyl rhodanine is preferably 1:(5-15), more preferably 1:(8-12), and most preferably 1:10.8.

In the present invention, the organic solvent is preferably a chlorinated alkane compound, more preferably a dichlorinated alkane compound or a trichloroalkane compound, most preferably dichloromethane or chloroform. In the present invention, the mass ratio of the volume of the organic solvent to the compound having the structure shown in formula IV is preferably (15-200) mL:1g, more preferably (20-180) mL:1g, most preferably For (25 ~ 140) mL: 1g.

In the present invention, in the presence of an organic solvent system and a catalyst, the compound having the structure shown in formula IV reacts with the electron-withdrawing monomer to obtain the D-A type small molecule compound described in the above technical solution. In the present invention, when the electron-withdrawing monomer is malononitrile, the temperature of the reaction is preferably 30°C to 50°C, more preferably 35°C to 45°C, most preferably 40°C; The time is preferably 12h-36h, more preferably 15h-33h, most preferably 16h-30h. Specifically, in the embodiment of the present invention, the reaction can be carried out overnight to obtain the D-A type small molecular compound having the structure shown in formula I.

In the present invention, when the electron-withdrawing monomer is 2-ethylhexyl cyanoacetate, the reaction temperature is preferably 20°C to 40°C, more preferably 25°C to 35°C, most preferably 30°C; specifically, in the examples of the present invention, the reaction is carried out at room temperature without heating or cooling the reaction system; the reaction time is preferably 8h-18h, more preferably 10h-15h , most preferably 12h.

In the present invention, when the electron-withdrawing monomer is 2-ethylrhodanine, the reaction is preferably carried out under reflux conditions; the reaction time is preferably 12h to 36h, more preferably 15h to 33h, Most preferably 16h～30h. Specifically, in an embodiment of the present invention, the reaction can be carried out overnight to obtain a D-A type small molecule compound having the structure shown in formula III.

After the reaction is completed, the present invention preferably performs column chromatography purification on the obtained reaction product. In the present invention, the solvent in the reaction product is preferably removed before performing the column chromatography. The present invention has no special limitation on the device of the column chromatography, and a chromatography column well-known to those skilled in the art can be used; in the embodiment of the present invention, a silica gel column is specifically used. In the present invention, the eluent used in the column chromatography process preferably includes methylene chloride and n-hexane; the volume ratio of methylene chloride and n-hexane is preferably 2:1.

The present invention has no special restrictions on the method for removing the solvent in the reaction product, and the technical solution for removing the solvent well known to those skilled in the art can be used; solvent to obtain crude product. In the present invention, the distillation is preferably vacuum distillation or rotary evaporation. In the present invention, the vacuum degree of the vacuum distillation is preferably 0.09-0.11 MPa, more preferably 0.1 MPa; the temperature of the vacuum distillation is preferably 30-40°C, more preferably 35°C. In the present invention, the vacuum degree of the rotary evaporation is preferably 0.09-0.11MPa, more preferably 0.1MPa; the temperature of the rotary evaporation is preferably 30-40°C, more preferably 35°C; the rotation speed of the rotary evaporation It is preferably 75 to 85 rpm, more preferably 80 rpm.

When the electron-withdrawing monomer is malononitrile, in the present invention, before removing the solvent in the reaction product, the reaction solution obtained by the reaction is extracted with water, and the obtained organic layer is distilled to remove the solvent. In the present invention, the volume ratio of the volume of the added water to the reaction solution is preferably 1: (0.75～1); the extraction agent for the extraction is preferably dichloromethane, and the volume of the dichloromethane is the same as the volume ratio of the reaction solution. The volume ratio of the reaction solution is preferably 1:(0.75-1).

After the organic layer is obtained by extraction, the present invention preferably washes and filters the organic layer to remove the solvent in the organic layer. In the present invention, the washing is preferably performed with brine, and the mass concentration of the brine is preferably 0.3-0.4 g/mL, more preferably 0.36 g/mL.

When the electron-withdrawing monomer is 2-ethylrhotanine, after the extraction, the obtained organic layer is preferably dried and filtered in sequence. In the present invention, the drying is preferably done with a desiccant, and the desiccant is preferably anhydrous sodium sulfate.

The small molecular compound of D-A structure provided by the invention has the phenomenon of internal charge transfer, and its absorption spectrum matches well with the solar spectrum, which helps to improve the absorption performance of the material.

The present invention adjusts the energy level of the material by changing the electron-withdrawing monomer in the small molecule of the D-A structure, so as to facilitate the synthesis of a narrow-band photovoltaic material with good performance; moreover, in the present invention, based on phenothiazine itself, it has moderate spatial deformation The addition of side chain alkyl groups makes it a non-planar geometry, and the N and S atoms on the phenothiazine unit help to enhance the electron-donating ability of the main chain of the molecule.

Based on this, the present invention also provides the application of the DA-type small molecule compound described in the above technical solution or the DA-type small molecule compound prepared by the preparation method described in the above technical solution in solar cells. Specifically, a solar cell device is provided, including an ITO glass layer, a ZnO layer disposed on the ITO glass layer, a DA type small molecule compound layer disposed on the ZnO layer, and a DA type small molecule compound layer disposed on the DA type small molecule compound layer. A _C60 electron transport layer on the compound layer, a cathode buffer layer disposed on the _C60 electron transport layer, and an Ag electrode layer disposed on the cathode buffer layer;

The D-A type small molecule compound is the D-A type small molecule compound described in the above technical scheme or the D-A type small molecule compound prepared by the preparation method described in the above technical scheme.

The solar cell device provided by the invention comprises an ITO glass layer and a ZnO layer arranged on the ITO glass layer. The present invention has no special limitation on the parameters of the ITO glass layer and the ZnO layer, and the ITO glass layer and the ZnO layer in the solar cell well-known to those skilled in the art can be used. In the present invention, the thickness of the ITO glass layer is preferably 1-3 mm, more preferably 2 mm; the thickness of the ZnO layer is preferably 50-100 nm, more preferably 60-85 nm, most preferably 65-75 nm.

The solar cell device provided by the present invention includes a D-A type small molecule compound layer disposed on the ZnO layer. In the present invention, the thickness of the D-A type small molecule compound layer is preferably 40-50 nm, more preferably 42-47 nm. .

The solar device provided by the present invention comprises a _C60 electron transport layer arranged on the DA type small molecule compound layer, a cathode buffer layer arranged on the _C60 electron transport layer, and an Ag electrode arranged on the cathode buffer layer. electrode layer. In the present invention, the thickness of the C ₆₀ electron transport layer is preferably 40-60 nm, more preferably 45-52 nm; the thickness of the cathode buffer layer is preferably 5-10 nm, more preferably 6-8 nm; the Ag The thickness of the electrode layer is preferably 60 to 90 nm, more preferably 65 to 80 nm, most preferably 70 to 75 nm.

In the present invention, the cathode buffer layer is preferably obtained by evaporation of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS). In the present invention, the PEDOT:PSS is preferably a product with a solid content of 1.3%-1.7% as described in CAS:155090-83-8. In the present invention, the PEDOT:PSS is preferably mixed with ethanol to obtain the PEDOT:PSS solution, which is then evaporated to obtain a cathode buffer layer. In the present invention, the mass ratio of PEDOT:PSS to ethanol in the PEDOT:PSS solution is preferably 1:(9-11), more preferably 1:10.

The present invention has no special limitation on the preparation method of the solar cell device, and the technical solutions for solar cell preparation well-known to those skilled in the art can be adopted. In an embodiment of the present invention, the method for preparing the solar cell device preferably includes the following steps:

The ITO glass is cleaned and treated with ultraviolet and ozone in sequence to obtain the ITO glass layer;

On the ITO glass layer, ZnO, DA type small molecule compound, C ₆₀ , PEDOT:PSS and metal electrode Ag are sequentially evaporated, and a ZnO layer, DA type small molecule compound layer, C ₆₀ Electron transport layer, cathode buffer layer and Ag electrode layer to obtain a solar cell device.

In the invention, the ITO glass is cleaned and treated with ultraviolet and ozone in sequence to obtain the ITO glass layer. In the present invention, the cleaning is preferably ultrasonic cleaning with ethanol, ultrasonic cleaning with acetone, ultrasonic cleaning with isopropanol and ultrasonic cleaning with deionized water; after each ultrasonic cleaning, deionized water rinsing is preferably performed. In the present invention, the time of the ethanol ultrasonic cleaning is preferably 10min～20min, more preferably 15min; the time of the acetone ultrasonic cleaning is preferably 10min～20min, more preferably 15min; the time of the isopropanol ultrasonic cleaning It is preferably 10 min to 20 min, more preferably 15 min; the time for ultrasonic cleaning with deionized water is preferably 10 min to 20 min, more preferably 15 min.

After the cleaning of the ITO glass is completed, the present invention preferably blows the cleaned ITO glass dry under nitrogen.

In the present invention, the time of the ultraviolet ozone treatment is preferably 20 min to 40 min, more preferably 25 min to 35 min, and most preferably 30 min. The present invention has no special limitation on the device for the ultraviolet ozone treatment, and the ultraviolet ozone instrument well-known to those skilled in the art can be used.

After the ITO glass layer is obtained, the present invention sequentially vapor-deposits ZnO, DA type small molecular compound, C ₆₀ , PEDOT:PSS and metal electrode Ag on the ITO glass layer, and sequentially forms a ZnO layer, DA Type small molecule compound layer, C ₆₀ electron transport layer, cathode buffer layer and Ag electrode layer to obtain a solar cell device.

In the present invention, the vacuum degree of evaporating ZnO is preferably 3×10 ^-3 ~ 4×10 ^-4 Pa, more preferably 3×10 ^{- 4} Pa; the rate of evaporating ZnO is preferably more preferably

In the present invention, the vacuum degree for vapor deposition of the DA type small molecule compound is preferably 3×10 ^-4 ~ 4×10 ^-4 Pa, more preferably 3.5×10 ^-4 Pa; the vapor deposition of the DA type small molecule The rate of the compound is preferably more preferably

In the present invention, the degree of vacuum for evaporating C ₆₀ is preferably 3×10 ^-4 ~ 4×10 ^-4 Pa, more preferably 3.5×10 ^{- 4} Pa; the rate of evaporating C ₆₀ is preferably more preferably

In the present invention, the vacuum degree of vapor deposition of the PEDOT:PSS is preferably 3×10 ^-3 ~ 4×10 ^-4 Pa, more preferably 3×10 ^-4 Pa; the rate of vapor deposition of the PEDOT:PSS is preferably for more preferably

In the present invention, the vacuum degree of Ag deposition on the metal electrode is preferably 3×10 ^-3 ~ 4×10 ^-4 Pa, more preferably 3×10 ^-4 Pa; the Ag deposition rate on the metal electrode is preferably for more preferably

The present invention has no special limitation on the equipment used for the evaporation, and a vacuum evaporation system well known to those skilled in the art can be used. During the evaporation process of the present invention, it is preferable to use a quartz crystal oscillator to monitor the evaporation rate and film thickness of the material.

The D-A type small molecular compound provided by the present invention and its preparation method and application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the protection scope of the present invention.

In the following examples of the present invention, the compound having the structure shown in formula IV is obtained according to the following preparation method:

Phenothiazine (2g, 10mmol) was added to dimethyl sulfoxide (40mL), then sodium hydroxide (0.8g, 20mmol) was added, and the resulting mixture was stirred at room temperature for 30min, gradually 1-Bromohexadecane (4.88mL, 16mmol) was added dropwise, and the reaction was stirred at room temperature for 24h. After the reaction was completed, dimethyl sulfoxide was distilled off under reduced pressure, and the resulting material was extracted with CH ₂ Cl _2. The organic layer was washed with Anhydrous Na ₂ SO ₄ was dried, filtered, and the solvent was removed by distillation under reduced pressure, and the obtained crude product was purified by column chromatography (silica gel, petroleum ether) to obtain compound 1 as a yellow oil;

Under argon protection, dimethylformamide (12.46mL) was added to a 100mL three-necked flask, cooled in an ice bath, and phosphorus oxychloride (16.51mL) was added dropwise within 30min, and compound 1 (3g, 7.08 mmol) was dissolved in 10mL 1,2-dichloroethane and added dropwise to the above solution, heated to 95°C for 48 hours, cooled to room temperature after the reaction, poured into ice water, and dissolved in saturated sodium hydroxide solution The pH of the reactant was adjusted to 6-7, and then the resulting material was extracted with CH ₂ Cl ₂ , the organic layer was dried with anhydrous Na ₂ SO ₄ , the solvent was distilled off under reduced pressure, and the obtained crude product was passed through column chromatography (silica gel, CH ₂ Cl ₂ and n-hexane volume ratio is 3:1) to obtain compound 2 after purification;

Under argon protection, methanol (23.54mL), compound 2 (1.1g, 2.3mmol) and 2-thiopheneacetonitrile (0.624g, 5.07mmol) were added to a 100mL single-necked flask, and the catalyst potassium tert-butoxide was added and heated to The reaction was stirred at 50°C for 12 hours, cooled to room temperature after the reaction, and the solvent was spin-dried, and the obtained crude product was purified by column chromatography (silica gel, CH ₂ Cl ₂ ) to obtain compound 3 as a red solid;

Under argon protection, dimethylformamide (5mL) was added to a 100mL three-necked flask, cooled in an ice bath, and phosphorus oxychloride (5mL) was added dropwise within 30min, and compound 3 (1.3g, 1.95mmol ) was dissolved in 1,2-dichloroethane (3mL) and added dropwise to the above solution, heated to 95°C for 48 hours, cooled to room temperature after the reaction, poured into ice water, and washed with saturated sodium hydroxide solution The pH of the reaction solution was adjusted to 6-7, and then the obtained material was extracted with CH ₂ Cl ₂ , the organic layer was dried with anhydrous Na ₂ SO ₄ , the solvent was distilled off under reduced pressure, and the obtained crude product was subjected to column chromatography (silica gel, CH ₂ Cl ₂ ) was purified to obtain a red solid, which was the compound having the structure shown in Formula IV.

Example 1:

Under argon protection, 0.2g (0.277mmol) of the compound shown in the structure of Formula IV, 5mL CH ₂ Cl ₂ and 54mg malononitrile (0.831mmol) were added respectively to a 25mL round bottom flask; 15mg L-propane Dissolve L-alanine in 4.5 mL of absolute ethanol, add the obtained L-alanine solution dropwise into the flask, and stir and react at 40°C overnight;

Add 30 mL of water to the obtained reaction solution and extract with 50 mL of CH ₂ Cl ₂ , wash the obtained organic layer with 0.36 g/mL brine three times, filter, and distill under reduced pressure at a vacuum degree of 0.1 MPa and a distillation temperature of 35°C The solvent is removed to obtain the crude product;

The obtained crude product was purified by column chromatography. The column chromatography used a silica gel column, and the eluent of the column chromatography was CH ₂ Cl ₂ and n-hexane with a volume ratio of 2:1 to obtain 0.098 g of a dark red solid.

The yield of the product calculated by the present invention is 42.7%.

In the present invention, the obtained crimson solid is subjected to proton nuclear magnetic resonance spectrum measurement, and the result is: ¹ H NMR (CDCl ₃ , 400Hz, δ/ppm): 7.80-7.84(t, 2H, Ar-H), 7.66-7.71(t ,2H,Ar-H),7.53-7.55(d,1H,AR-H),7.41-7.47(t,1H,Ar-H),7.27(s,2H,thiophene-H),6.90-6.95(m ,2H,alkene-H),3.90-3.92(d,2H,N-CH ₂ ),1.84-1.85(d,2H,CH ₂ ),1.66-1.69(t,2H,CH ₂ ),1.40-1.44( m, 4H, CH ₂ ), 1.32 (s, 8H, CH ₂ ), 0.94-1.00 (t, 17H, CH ₂ , CH ₃ );

In the present invention, the obtained dark red solid is subjected to carbon nuclear magnetic resonance spectrum measurement, and the result is: ¹³ C NMR (CDCl ₃ , 100MHz, δ/ppm): 167.79, 157.07, 149.99, 148.72, 145.75, 141.91, 139.94, 134.74, 132.43, 131.16,130.90,130.14,129.68,128.80,128.25,127.61,126.21,126.17,124.10,123.75,116,115.53,102.73,53.44,48.61,38.71,31.93,30.34,29.71,29.67,29.61,29.53,29.37,29.16,28.92, 26.74, 26.58, 23.73;

The measurement results of hydrogen spectrum and carbon spectrum show that the dark red solid prepared in this embodiment has the structure shown in formula I.

Example 2:

Under argon protection, 0.2g (0.277mmol) of the compound having the structure shown in formula IV, 28mL CH ₂ Cl ₂ , 1.35mL (6.73mmol) 2-ethylhexylcyanoethyl Ester and catalytic amount of triethylamine, the resulting mixed solution was stirred and reacted at room temperature for 12h;

The obtained reaction solution was distilled off under reduced pressure to remove the solvent under the conditions of a vacuum degree of 0.1 MPa and a distillation temperature of 35° C. to obtain a crude product;

The obtained crude product was purified by column chromatography. The column chromatography used a silica gel column. The eluent of the column chromatography was CH ₂ Cl ₂ and n-hexane with a volume ratio of 2:1 to obtain 0.15 g of a dark red solid.

The yield rate of the product calculated by the present invention is 50%.

In the present invention, the obtained dark red solid is subjected to proton nuclear magnetic resonance spectrum measurement, and the result is: ¹ H NMR (CDCl ₃ , 400Hz, δ/ppm): 8.27 (s, 1H, Ar-H), 8.04 (s, 1H, Ar -H),7.93-7.95(d,1H,Ar-H),7.81-7.83(d,1H,Ar-H),7.67-7.68(d,1H,Ar-H),7.40-7.43(t,3H ,Ar-H,thiophene-H),6.90-6.93(m,2H,alkene-H),4.23(s,4H,O-CH ₂ ),3.74(s,2H,N-CH ₂ ),1.84(s ,3H,CH,CH ₂ ),1.71(s,3H,CH,CH ₂ ),1.63(d,9H,CH ₂ ),1.41-1.47(m,6H,CH ₂ ),1.25(s,15H,CH ₂ ),0.86-0.96(m,25H,CH ₂ ,CH ₃ );

In the present invention, the obtained dark red solid is subjected to carbon nuclear magnetic resonance spectrum measurement, and the result is: ¹³ C NMR (CDCl ₃ , 100MHz, δ/ppm): 162.67, 152.7, 148.44, 147.71, 145.98, 145.78, 141.19, 138.95, 135.64, 131.05,130.42,129.77,128.65,128.13,127.44,126.63,123.92,123.76,116.25,115.92,115.74,115.59,115.50,102.85,100.04,99.69,53.46,48.45,38.76,31.95,30.31,29.72,29.69,29.64, 29.57, 29.54, 29.39, 29.20, 28.92;

The measurement results of hydrogen spectrum and carbon spectrum show that the dark red solid prepared in this embodiment has the structure shown in formula II.

Example 3

Under argon protection, 0.2 g (0.277 mmol) of a compound having the structure shown in Formula IV, 28 mL of CHCl ₃ , 487.5 mg of 3-ethylrhodanine (3 mmol) and a catalytic amount of piperin were added to a 50 mL round bottom flask. Pyridine, the resulting mixed solution was refluxed for overnight reaction;

After cooling the obtained reaction solution to room temperature, add water to it and extract with CH ₂ Cl ₂ , dry the obtained organic layer with anhydrous Na ₂ SO ₄ successively, filter, and vacuum under the condition of 0.1MPa and distillation temperature of 35°C The solvent was distilled off under reduced pressure to obtain the crude product;

The obtained crude product was purified by column chromatography. The column chromatography used a silica gel column. The eluent of the column chromatography was CH ₂ Cl ₂ and n-hexane with a volume ratio of 2:1 to obtain 0.1 g of a purple solid.

The present invention calculates that the yield of the product is 35%.

In the present invention, the obtained crimson solid is subjected to proton nuclear magnetic resonance spectrum measurement, and the result is: ¹ H NMR (CDCl ₃ , 400Hz, δ/ppm): 7.54-7.55 (d, 4H, Ar-H), 7.0-7.27 (m ,4H,Ar-H,thiophene-H),6.87-6.92(t,2H,alkene-H),4.19-4.26(m,4H,N-CH ₂ ),3.72-3.75(d,2H,N-CH ₂ ),2.59-2.62(d,2H,CH ₂ ),2.50-2.56(t,2H,CH ₂ ),2.21-2.24(d,2H,CH ₂ ),2.1(s,2H,CH ₂ ),1.79 -1.82(t,29H,CH ₂ ,CH ₃ );

In the present invention, the obtained dark red solid is measured by carbon nuclear magnetic resonance spectrum, and the result is: ¹³ C NMR (CDCl ₃ , 100MHz, δ/ppm): 167.74, 132.49, 130.86, 128.80, 38.76, 37.11, 32.76, 31.92, 30.38, 30.03, 29.70, 29.50, 29.35, 28.93, 27.08, 23.77, 22.97, 22.68, 14.10, 14.02, 10.95;

The measurement results of hydrogen spectrum and carbon spectrum show that the purple-red solid prepared in this embodiment has the structure shown in formula III.

Example 4

The solar cell was prepared by using the compound prepared in Example 1. In this embodiment, the structure of the solar cell was ITO glass layer/ZnO layer/DA type small molecule compound layer/ _C60 layer/cathode buffer layer/Ag electrode layer.

The ITO glass was ultrasonically cleaned with ethanol, acetone, isopropanol, and deionized water for 15 minutes, dried with nitrogen, and then treated for 30 minutes in a UV-ozone instrument;

On the film-forming equipment in the vacuum evaporation box, ZnO, the compound prepared in Example 1, C ₆₀ , PEDOT:PSS and the metal electrode Ag were successively evaporated on the surface of ITO glass, and the vacuum degree of the evaporated organic material was 3× 10 ^-4 Pa, the evaporation rate is The vacuum degree of vapor deposition metal material is 3×10 ^-3 Pa, and the vapor deposition rate is During the evaporation process, a quartz crystal oscillator is used to monitor the evaporation rate and film thickness of the material. Among them, the thickness of the ITO glass layer is 2nm, the thickness of the ZnO layer is 50nm, the thickness of the DA type small molecule compound layer is 40nm, C ₆₀ The thickness of the electron transport layer is 40nm, the thickness of the cathode buffer layer is 10nm, and the thickness of the Ag electrode layer is 90nm; after the evaporation is completed, a complete organic small molecule solar cell device is obtained, and the device structure is shown in Figure 1.

The present invention uses AM1.5 with a light intensity of 100mW/cm ² to simulate sunlight irradiation, and under the simulated conditions, the open circuit voltage of the solar cell device is 0.626V, the short circuit current density is 7.56mA/cm ² , and the fill factor is 0.59, and the photoelectric energy conversion efficiency is 2.79%.

Example 5

The compound prepared in Example 2 was used to prepare a solar cell. In this embodiment, the structure of the solar cell was ITO glass layer/ZnO layer/DA type small molecule compound layer/ _C60 layer/cathode buffer layer/Ag electrode.

The ITO glass was ultrasonically cleaned with ethanol, acetone, isopropanol, and deionized water for 15 minutes, dried with nitrogen, and then treated for 30 minutes in a UV-ozone instrument;

On the film-forming equipment in the vacuum evaporation box, ZnO, the compound prepared in Example 2, C ₆₀ , PEDOT:PSS and the metal electrode Ag were successively evaporated on the surface of ITO glass, and the vacuum degree of the evaporated organic material was 3× 10 ^-4 Pa, the evaporation rate is The vacuum degree of vapor deposition metal material is 3×10 ^-3 Pa, and the vapor deposition rate is During the evaporation process, a quartz crystal oscillator is used to monitor the evaporation rate and film thickness of the material. Among them, the thickness of the ITO glass layer is 3nm, the thickness of the ZnO layer is 100nm, the thickness of the DA type small molecule compound layer is 50nm, and the C ₆₀ The electron transport layer has a thickness of 60 nm, the cathode buffer layer has a thickness of 5 nm, and the Ag electrode layer has a thickness of 60 nm. After the vapor deposition is completed, a complete organic small molecule solar cell device is obtained.

The present invention uses AM1.5 with a light intensity of 100mW/cm ² to simulate sunlight irradiation, and under the simulation conditions, the open circuit voltage of the solar cell device is 0.65V, the short circuit current density is 7.34mA/cm ² , and the fill factor is 0.51, and the photoelectric energy conversion efficiency is 2.43%.

Embodiment 6:

Using the compound prepared in Example 3 to prepare a solar cell, the structure of the solar cell in this embodiment is ITO glass layer/ZnO layer/DA type small molecule compound layer/ _C60 layer/cathode buffer layer/Ag electrode.

The ITO glass was ultrasonically cleaned with ethanol, acetone, isopropanol, and deionized water for 15 minutes, dried with nitrogen, and then treated for 30 minutes in a UV-ozone instrument;

On the film-forming equipment in the vacuum evaporation box, ZnO, the compound prepared in Example 3, C ₆₀ , PEDOT:PSS and the metal electrode Ag were successively evaporated on the surface of ITO glass, and the vacuum degree of the evaporated organic material was 3× 10 ^-4 Pa, the evaporation rate is The vacuum degree of vapor deposition metal material is 3×10 ^-3 Pa, and the vapor deposition rate is During the evaporation process, a quartz crystal oscillator is used to monitor the evaporation rate and film thickness of the material. Among them, the thickness of the ITO glass layer is 1nm, the thickness of the ZnO layer is 70nm, the thickness of the DA type small molecule compound layer is 45nm, and the C ₆₀ The electron transport layer has a thickness of 50 nm, the cathode buffer layer has a thickness of 8 nm, and the Ag electrode layer has a thickness of 80 nm. After the vapor deposition is completed, a complete organic small molecule solar cell device is obtained.

The present invention uses AM1.5 with a light intensity of 100mW/cm ² to simulate sunlight irradiation, and under the simulated conditions, the open circuit voltage of the device is 0.636V, the short circuit current density is 7.42mA/cm ² , and the fill factor is 0.53. The photoelectric energy conversion efficiency is 2.54%.

As can be seen from the above examples, the D-A type small molecule compound provided by the present invention has a structure shown in formula I, formula II or formula III, with phenothiazine as electron-donating group, malononitrile, 2-ethyl Hexyl cyanoacetate or 2-ethylrhodanine as electron-withdrawing groups. In the present invention, there is a phenomenon of internal charge transfer in the small molecule of the D-A structure, which helps to improve the absorption performance of the material; the electron-withdrawing group can adjust the energy level of the small molecule combination of the material to obtain a narrow band with good performance. Department of photovoltaic materials. Moreover, phenothiazine itself has moderate steric deformability and the introduction of side chain alkyl makes it have a non-planar geometric configuration. The N and S atoms on the phenothiazine unit help to enhance the electron donation of the main chain of the molecule. ability. In addition, the small molecular compound provided by the present invention also has the following characteristics: (1) There are many active atoms on the ring, and the structure of the molecule can be modified by introducing multiple functional groups (2) The transfer ability of electrons is very strong (3) The formed positron Ions are relatively stable (4) thermal stability and chemical stability are high. Experimental results show that the solar cell device including the D-A type small molecule compound layer provided by the invention has a relatively high photoelectric energy conversion efficiency of about 2.8%.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (11)

1. D-A type small molecular compound having the structure shown in formula I, formula II or formula III: 2. the preparation method of the described D-A type small molecular compound of claim 1, comprises the following steps: Under a protective gas atmosphere, the compound having the structure shown in formula IV, the electron-withdrawing monomer and the catalyst are reacted in an organic solvent system to obtain the D-A small molecule compound with the structure shown in formula I, formula II or formula III; The electron-withdrawing monomer is malononitrile, 2-ethylhexyl cyanoacetate or 3-ethylrhodanine. 3. The preparation method according to claim 2, characterized in that, when the electron-withdrawing monomer is malononitrile, the catalyst is L-alanine. 4. The preparation method according to claim 2, characterized in that, when the electron-withdrawing monomer is 2-ethylhexyl cyanoacetate, the catalyst is a tertiary amine. 5. The preparation method according to claim 2, characterized in that, when the electron-withdrawing monomer is 3-ethylrhodanine, the catalyst is piperidine. 6. The preparation method according to claim 2, characterized in that, the organic solvent is a chlorinated alkane compound. 7. The preparation method according to claim 2, characterized in that the molar ratio of the compound represented by the formula IV to the electron-withdrawing monomer is 1:(2-30). 8. The preparation method according to any one of claims 2-7, characterized in that, after the reaction, it further comprises: performing column chromatography on the reaction product obtained in the reaction. 9 . The preparation method according to claim 8 , further comprising: extracting the reaction solution of the reaction before the column chromatography. 10 . 10. The application of the D-A type small molecule compound of claim 1 or the D-A type small molecule compound prepared by the preparation method of any one of claims 2 to 9 in solar cells. 11. A solar cell device, comprising an ITO glass layer, a ZnO layer arranged on the ITO glass layer, a DA type small molecule compound layer arranged on the ZnO layer, and a DA type small molecule compound layer arranged on the DA type small molecule compound layer The C ₆₀ electron transport layer on the top, the cathode buffer layer arranged on the C ₆₀ electron transport layer, and the Ag electrode layer arranged on the cathode buffer layer; The D-A type small molecule compound is the D-A type small molecule compound described in claim 1 or the D-A type small molecule compound prepared by the preparation method described in any one of claims 2-9.