1. The organic solar cell small molecule donor material is characterized in that the structural formula of the organic solar cell small molecule donor material E-1 is shown as the formula (1):

2. the organic solar cell small molecule donor material is characterized in that the structural formula of the organic solar cell small molecule donor material E-2 is shown as the formula (2):

3. the preparation method of the organic solar cell small molecule donor material according to claim 1, wherein the preparation method comprises the following steps:

4. the preparation method of the organic solar cell small molecule donor material according to claim 2, characterized in that the preparation method comprises the following steps:

5. the method of claim 3, comprising the steps of:

(1) mass per reactant a: b is 1: 2.5, adding reactants into a 100ml three-neck flask, adding 25ml to 35ml of toluene as a solvent, adding tetrakis (triphenylphosphine) palladium accounting for 5 percent of the total amount of raw materials as a catalyst, heating and refluxing for 10 hours at 110 ℃, and carrying out Stille coupling reaction;

(2) the mass of the reactants C: D ═ 1: 10, adding the reactant into a 100ml three-neck flask, adding 25 ml-35 ml chloroform as a solvent, adding 5% pyridine of the total amount of the raw materials as a catalyst, and heating and refluxing for 12 h-18 h at 65 ℃ to perform Knoevenagel condensation reaction.

6. The method of claim 4, comprising the steps of:

(1) mass per reactant a': b' ═ 1: 2.5, adding reactants into a 100ml three-neck flask, adding 25ml to 35ml of toluene as a solvent, adding tetrakis (triphenylphosphine) palladium accounting for 5 percent of the total amount of raw materials as a catalyst, heating and refluxing for 10 hours at 110 ℃, and carrying out Stille coupling reaction;

(2) the amount of the reactants C ', D' ═ 1: 10, adding the reactant into a 100ml three-neck flask, adding 25 ml-35 ml chloroform as a solvent, adding 5% pyridine of the total amount of the raw materials as a catalyst, and heating and refluxing for 12 h-18 h at 65 ℃ to perform Knoevenagel condensation reaction.

7. The application of the organic solar cell small molecule donor material as claimed in claim 1 or 2, which is applied to an organic solar cell device, wherein the organic solar cell device comprises a transparent substrate layer, an anode interface layer, an active layer, a cathode interface layer and a cathode layer which are sequentially stacked, and the active layer is made of the organic solar cell small molecule donor material.

Background

The organic solar cell is used as a renewable energy source, and has the advantages of light weight, low price, large-area preparation and the like. But currently cannot be commercialized due to its low energy conversion efficiency (PCE). Under the continuous efforts of global scientists, the energy conversion efficiency of the single organic solar cell device in the laboratory is more than 18 percent at present. Recently, research finds that small molecule donors have the advantages of single structure, easiness in purification, high mobility, adjustable energy level, excellent solubility and the like compared with polymer donors.

Compared with other donor structure central nuclei, Benzodithiophene (BDT) has a large rigid plane conjugated structure, can improve the delocalization capability of pi electrons and pi-pi interaction between molecules, is easy to chemically modify a BDT unit, is convenient to synthesize, has high photoelectric efficiency, and is a well-known electron-rich molecule. Therefore, the introduction of thiophene into BDT causes red shift of the absorption spectrum, resulting in an increase in the absorption wavelength and an increase in Jsc and FF.

Fluorine atoms are an effective electron withdrawing group, have strong electronegativity and small size. The strong electronegativity of fluorine atoms can reduce HOMO and LUMO simultaneously without causing severe steric hindrance. The small size gives the molecular framework greater planarity and facilitates charge transport. The introduction of fluorine atoms on the central core allows it to have a relatively low peak occupied molecular orbital and high electron mobility. In addition, the introduction of fluorine enhances the non-covalent interaction and intermolecular aggregation of fluorine and hydrogen sulfide, thereby improving the film morphology.

4, 4-dihexyl-Dithienocyclopentadiene (DTC) and 4, 4-diethyl-Dithienosilene (DTS) are used as pi-bridges, good Internal Charge Transfer (ICT) can be provided due to the basic characteristics of good fused ring structure, electron-rich groups and the like, and strong non-covalent interaction (H, F, S, F, S, N) exists in the molecule, so that the charge transfer is facilitated. 4, 4-dihexyl-dithienocyclopentadiene and 4, 4-diethyl-dithienosilene are used as donors with less rich electrons, and a unit with less rich electrons is used as a pi bridge, so that the Highest Occupied Molecular Orbital (HOMO) of a donor molecule can be reduced, and the open-circuit voltage (Voc) of the small-molecule donor-fullerene heterojunction (BHJ) solar cell is increased

Butynoxide is widely used as an electron withdrawing group in organic solar cells, rhodanine based organic solar cells have higher open circuit voltages and they have well matched energy levels and optical absorption with the well known P3HT donor, good phase separated film morphology and front dominant crystallinity and can suppress charge recombination. The introduction of 3-butyl rhodanine greatly enhances the light absorption capability of the donor, so that higher Jsc is obtained.

An increase in the number of terminal carbon atoms can improve the solubility of the material, but also can affect intermolecular packing. The packing of molecules becomes disordered the longer the length of the alkyl chain. Alkyl chains of suitable length relative to longer alkyl chains also improve the bulk order of the molecule while ensuring solubility.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the organic solar cell small molecule donor material, the preparation method and the application, and the organic solar cell small molecule donor material has the advantages of stable material, simple process, easy modification and energy conversion efficiency improvement.

In order to solve the technical problems, the invention provides the following technical scheme:

the organic solar cell small molecule material E-1 has a structural formula shown in formula (1):

formula (1).

The invention provides an organic solar cell micromolecule donor material which is a compound taking benzodithiophene as a core, 4-dihexyl-dithienocyclopentadiene as a pi bridge and 3-butylrhodanine as an end group.

A preparation method of an organic solar cell donor material comprises the following steps:

the preparation method comprises the following steps:

(1) mass per reactant a: b is 1: 2.5, adding reactants into a 100ml three-neck flask, adding 25ml to 35ml of toluene as a solvent, adding tetrakis (triphenylphosphine) palladium accounting for 5 percent of the total amount of raw materials as a catalyst, heating and refluxing for 10 hours at 110 ℃, and carrying out Stille coupling reaction;

(2) the mass of the reactants C: D ═ 1: and 5, adding the reactant into a 100ml three-neck flask, adding 25ml to 35ml of chloroform as a solvent, adding 5 percent of pyridine of the total amount of the raw materials as a catalyst, and heating and refluxing for 6h to 8h at 65 ℃ to perform Knoevenagel condensation reaction.

The organic solar cell device comprises a transparent substrate layer, an anode interface layer, an active layer, a cathode interface layer and a cathode layer which are sequentially stacked, wherein the active layer is made of the organic solar cell micromolecule donor material.

The invention provides another organic solar cell small molecule material, wherein the structural formula of the organic solar cell small molecule material E-2 is shown as the formula (2):

formula (2).

The invention provides another organic solar cell micromolecule donor material which is a compound taking benzodithiophene as a core, 4-diethyl-dithienosilene hetero cyclopentadiene as a pi bridge and 3-butyl rhodanine as an end group.

A preparation method of an organic solar cell donor material comprises the following steps:

the preparation method comprises the following steps:

(1) mass per reactant a': b' ═ 1: 2.5, adding reactants into a 100ml three-neck flask, adding 25ml to 35ml of toluene as a solvent, adding tetrakis (triphenylphosphine) palladium accounting for 5 percent of the total amount of raw materials as a catalyst, heating and refluxing for 10 hours at 110 ℃, and carrying out Stille coupling reaction;

(2) the amount of the reactants C ', D' ═ 1: and 5, adding the reactant into a 100ml three-neck flask, adding 25ml to 35ml of chloroform as a solvent, adding 5 percent of pyridine of the total amount of the raw materials as a catalyst, and heating and refluxing for 6h to 8h at 65 ℃ to perform Knoevenagel condensation reaction.

The organic solar cell device comprises a transparent substrate layer, an anode interface layer, an active layer, a cathode interface layer and a cathode layer which are sequentially stacked, wherein the active layer is made of the organic solar cell micromolecule donor material.

The invention has the following beneficial effects:

the micromolecule material is formed by copolymerizing a 3-hexyl rhodanine electron-withdrawing group serving as a terminal group, a pi bridge unit and a phenmediphene structural unit, so that the material is stable.

The material is a micromolecular material, has a simple synthesis process and is easy to modify compared with a polymer, and is suitable for commercial production.

The material is of an A-pi-D-pi-A structure, the structure is more stable, and the spectrum can be subjected to red shift, so that the material can absorb more solar spectra, and the energy conversion efficiency is improved.

The strong electronegativity of fluorine atoms can simultaneously reduce HOMO and LUMO without generating serious steric hindrance, and small-sized atoms endow the molecular skeleton with greater planarity and promote electron transport.

Drawings

FIG. 1 is a J-V characteristic curve of a photovoltaic device with one of the small molecular materials E-1/E-2 as a donor and an acceptor as Y6;

fig. 2 is a schematic diagram of a solar cell device.

Detailed Description

The organic solar cell small molecule donor material and the device provided by the invention are further explained in the following with the accompanying drawings.

Example 1

An organic solar cell small molecule donor material, wherein the structural formula of the organic solar cell small molecule donor material E-1 is shown as the formula (1):

formula (1)

The preparation process is as follows:

the preparation method comprises the following steps:

in a first step, the mass of the reactants A: b is 1: 2.5, adding 0.6gA and 0.72gB into a 100ml three-neck flask, adding 30ml toluene as a solvent, adding 0.04g tetrakis (triphenylphosphine) palladium as a catalyst, heating and refluxing for 12h at 110 ℃ in an anhydrous and oxygen-free environment, and carrying out Stille coupling reaction;

secondly, after the reaction is stopped, the obtained product is dissolved by chloroform after rotary evaporation, is extracted by ultrapure water for three times, is subjected to rotary evaporation, and is purified and separated by column chromatography to obtain an intermediate product C (0.5g, the yield is 62.5%);

third, the mass of the reactants C: d is 1: 10, adding 0.50gC and 0.07gD into a 100ml three-neck flask, adding 25ml chloroform as a solvent and 0.15ml piperidine as a catalyst, heating and refluxing for 12h at 65 ℃ in an anhydrous and oxygen-free environment, and carrying out Knoevenagel condensation reaction.

Fourthly, settling the obtained product with methanol for 3h, standing, performing suction filtration by using a mobile phase filter, drying, and performing column chromatography purification and separation to obtain a final product E-1(0.39, the yield is 62%)

1H NMR(400MHz,CDCl3)δ7.87(s,18H),7.87(s,12H),7.67(s,34H),7.67(s,12H),7.21(s,12H),7.28–7.04(m,103H),7.19(s,12H),7.17(s,12H),7.00(s,3H),4.23–4.03(m,34H),2.84(d,J＝6.4Hz,30H),2.14–1.64(m,101H),1.54(s,35H),1.51–1.28(m,125H),1.12(ddd,J＝67.3,18.4,11.3Hz,207H),0.95(d,J＝7.1Hz,107H),0.87–-0.19(m,191H),-0.00(s,71H),-0.00(s,80H).

Example 2

An organic solar cell small molecule donor material, wherein the structural formula of the organic solar cell small molecule donor material E-2 is shown as the formula (2):

formula (2)

The preparation process is as follows:

the preparation method comprises the following steps:

in a first step, the ratio of the mass of reactants A': b' ═ 1: 2.5, adding 0.4gA and 0.51gB into a 100ml three-neck flask, adding 30ml toluene as a solvent, adding 0.04g tetrakis (triphenylphosphine) palladium as a catalyst, heating and refluxing for 14h at 110 ℃ in an anhydrous and oxygen-free environment, and carrying out Stille coupling reaction;

secondly, after the reaction is stopped, the obtained product is dissolved by chloroform after rotary evaporation, is extracted by ultrapure water for three times, is subjected to rotary evaporation and column chromatography purification and separation to obtain an intermediate product C' (0.45g, the yield is 75%);

third, according to the mass quantity C' of reactants: d ═ 1: 10, adding 0.35gC 'and 0.48 gD' into a 100ml three-neck flask, adding 35ml chloroform as a solvent and 0.4ml pyridine as a catalyst, heating and refluxing for 18h at 65 ℃ in an anhydrous and oxygen-free environment, and carrying out Knoevenagel condensation reaction.

Fourthly, settling the obtained product with methanol for 3h, standing, performing suction filtration by using a mobile phase filter, drying, and performing column chromatography purification and separation to obtain a final product E-2(0.26g, the yield is 60%)

1H NMR(400MHz,CDCl3)δ7.87(s,18H),7.87(s,12H),7.67(s,34H),7.67(s,12H),7.21(s,12H),7.28–7.04(m,103H),7.19(s,12H),7.17(s,12H),7.00(s,3H),4.23–4.03(m,34H),2.84(d,J＝6.4Hz,30H),2.14–1.64(m,101H),1.54(s,35H),1.51–1.28(m,125H),1.12(ddd,J＝67.3,18.4,11.3Hz,207H),0.95(d,J＝7.1Hz,107H),0.87–-0.19(m,191H),-0.00(s,71H),-0.00(s,80H)。

Example 3

One of the materials obtained in example 1 and example 2 is used as a donor material, and the application thereof in an organic solar cell device is illustrated.

The organic solar cell device comprises a transparent substrate layer, an anode interface layer, an active layer, a cathode interface layer and a cathode layer which are sequentially stacked, wherein the active layer is made of organic solar cell micromolecule donor materials.

The following examples will illustrate the organic solar cell small molecule donor materials mentioned in the present invention and the application process thereof in organic solar cell devices, but the application of the present invention is not limited to the following examples.

The specific preparation process of the device is as follows:

firstly, ultrasonically cleaning a patterned conductive ITO glass substrate for 30min by using detergent powder, deionized water, acetone and isopropanol in sequence, and finally performing primula in a clean isopropanol solution;

secondly, drying the cleaned ITO glass by using a nitrogen air gun, and then placing the cleaned ITO glass under an ultraviolet ozone lamp for treatment for 15min so as to increase the hydrophilicity of the surface of the substrate and improve the work function of an ITO electrode, thereby being beneficial to energy level matching of each layer in a device and promoting cavity extraction;

thirdly, spin-coating a layer of PEDOT on the substrate, namely PSS solution is used as a hole transport layer, then immediately placing the whole substrate on an annealing table at 130 ℃, and annealing for 20min to improve the film-forming property of a hole transport layer film;

fourthly, spin-coating the small molecule donor and PTB7-Th blended photoactive layer in a glove box, and then annealing for 10min on an annealing table at 110 ℃;

fifthly, spin-coating PDiNO solution in a glove box as a cathode interface layer

And sixthly, evaporating a 100 nanometer Al layer in the vacuum evaporation chamber.

J-V curve test is carried out on the prepared device, and relevant performance parameters are obtained as shown in the following table.

Table 1 shows the performance parameters of ITO/PEDOT/PSS/E/Y6/PDINO/Al devices

TABLE 1

The above description is only for the purpose of illustrating the present invention and is not to be construed as limiting the invention, and all modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the present invention.