Organic solar cell active layer based on oligomer electron acceptor and application thereof

Abstract

The invention discloses an organic solar cell active layer based on an oligomer electron acceptor and application thereof, and belongs to the technical field of organic photovoltaic cells, the organic solar cell active layer based on the oligomer electron acceptor comprises a polymer electron donor material and two electron acceptor materials, wherein one electron acceptor material is an A-DA 'D-A type electron acceptor material, the other electron acceptor material is an oligomer electron acceptor, the oligomer electron acceptor takes a benzothiadiazole trapezoidal fused ring structure as a core, a side chain is substituted by a branched alkyl chain, and the side chain is substituted by a branched alkyl chain. The dimer material is formed by connecting small molecule non-fullerene receptors with electron-withdrawing end groups at two ends, namely dichloro-substituted indandione and monobromo-substituted cyano indanone, through bithiophene or bithiophene containing low polyethylene glycol side chains. The ternary organic solar cell prepared based on the oligomer electron acceptor has high open-circuit voltage, short-circuit current density and filling factor, and the highest energy conversion efficiency is 19.04%.

Description

Technical Field

[0001] This invention belongs to the field of organic photovoltaic cell technology, specifically relating to an organic solar cell active layer based on oligomeric electron acceptors and its application. Background Technology

[0002] In recent years, with the continuous development of novel organic semiconductor materials and the optimization of device structures, the power conversion efficiency (PCE) of organic solar cells has exceeded 20%, demonstrating enormous application potential. Among these advancements, the development of non-fullerene electron acceptor materials has played a crucial role in improving the performance of organic solar cells. Compared with traditional fullerene derivatives, non-fullerene electron acceptors possess advantages such as tunable molecular structure, wide spectral absorption range, and easily modulated energy level structure, providing new insights for designing high-performance organic solar cells.

[0003] Chinese patent document CN113480560A discloses a method for preparing a non-fullerene electron acceptor, its product, and its application. This material uses a benzotrithiophene electron-donating group as the central arm unit and a fused-ring structure as the arm unit. Heteroatoms are introduced onto the fused ring and modified with side groups. The end groups are capped with 3-(dicyanomethylene)indophenone groups and their derivatives. It exhibits excellent thin-film stability, high charge mobility, excellent molar absorptivity, and good thin-film morphology, enabling the fabrication of high-efficiency organic solar cell devices. Chinese patent document CN112778327A discloses an organic non-fullerene electron acceptor material, its preparation method, and its application. This invention's non-fullerene small molecule acceptor material has a fused-ring conjugated group at its center, including ADA and ADADA structures, and is terminated with a trifluoromethyl-substituted 1,3-indanedione derivative. This organic non-fullerene electron acceptor material has good solubility, film-forming properties, and high electron mobility, making it suitable for fabricating high-energy-conversion-efficiency organic solar cells.

[0004] Among numerous non-fullerene electron acceptor materials, dimer electron acceptor materials have attracted considerable attention due to their unique molecular structure and excellent photoelectric properties (as illustrated in Chinese patent document CN119528942A). Dimeric electron acceptor materials typically consist of two small-molecule electron acceptor units connected by a conjugated bridge. This structure not only broadens the spectral absorption range of the material but also optimizes the molecular energy level structure, increasing the glass transition temperature and thus improving the photoelectric conversion efficiency and morphological stability of organic solar cells. Furthermore, by rationally designing the conjugated bridge and electron acceptor units, the crystallinity, charge transport properties, solubility in non-halogen solvents, and compatibility with donor materials can be further controlled, providing a new approach for developing high-performance, high-stability organic solar cells that can be prepared using green solvents. Summary of the Invention

[0005] This invention provides an active layer for organic solar cells based on oligomeric electron acceptors, wherein the oligomeric electron acceptors have a broadened spectral absorption range, optimized energy level structure, and good non-halogen solution processing performance, which can significantly improve the photoelectric conversion efficiency of organic solar cells.

[0006] The specific technical solution adopted is as follows:

[0007] An active layer for an organic solar cell based on an oligomeric electron acceptor includes a polymeric electron donor material and two electron acceptor materials, wherein one electron acceptor material is an A-DA'DA type electron acceptor material, and the other electron acceptor material is an oligomeric electron acceptor. The structural formula of the oligomeric electron acceptor is shown in any of the following formulas:

[0008]

[0009]

[0010] The oligomeric electron acceptor material was designed and synthesized by the inventors. It consists of two small-molecule electron acceptor units connected by a conjugate bridge. Oligomeric glycol side chains can also be introduced into the conjugate bridge structure. The small-molecule electron acceptor units possess strong electron-withdrawing ability and good planarity, contain electron-deficient groups, and have strong charge transport capabilities. Introducing oligomeric glycol side chains into the molecular bridge structure is one of the key innovations of this invention. The oligomeric glycol side chains have excellent flexibility and hydrophilicity, which can significantly improve the solubility and film-forming properties of the material in non-halogen solvents without affecting its photoelectric properties. This overcomes the deficiency of excessive aggregation of electron acceptor materials during film formation in non-halogen solvents. Based on this oligomeric electron acceptor, this invention has prepared an active layer and an organic solar cell. The organic solar cell exhibits excellent performance, possessing high open-circuit voltage, high short-circuit current, and high fill factor.

[0011] Oligomeric electron acceptor materials are small molecule non-fullerene acceptors with a benzothiadiazole-like ladder-shaped fused ring structure as the core, branched alkyl chains as the side chains, and dichloro-substituted indanedione and monobromo-substituted cyanoindanedione as the electron-withdrawing end groups at both ends, which are connected by bithiophene or bithiophene containing oligoethylene glycol side chains to form a dimer material.

[0012] Preferably, the polymer electron donor material is D18 or PM6, and the A-DA'DA type electron acceptor material is L8-BO or BTP-eC9, with the following chemical structural formula:

[0013]

[0014] Furthermore, in the organic solar cell active layer based on oligomer electron acceptors, the mass ratio of polymer electron donor material, A-DA'DA type electron acceptor material and oligomer electron acceptor is 1:1.2:0.05~0.1.

[0015] More preferably, an active layer solution comprising a polymer electron donor material, an A-DA'DA type electron acceptor material, and an oligomeric electron acceptor is prepared, and the active layer solution is spin-coated into a film with a thickness of 50–300 nm. After annealing, an organic solar cell active layer based on oligomeric electron acceptors is obtained.

[0016] In a further preferred embodiment, the active layer solution also includes the additive 3,5-dichlorobromobenzene (DCBB), dissolved in chloroform at a concentration of 10 mg / mL. The additive improves the morphology of the active layer and enhances charge transport capabilities; the DCBB will volatilize after annealing.

[0017] Further preferred, the annealing temperature is 80–200℃, and the annealing time is 5–30 min.

[0018] The present invention also provides an organic solar cell, including the aforementioned organic solar cell active layer based on oligomer electron acceptors.

[0019] Preferably, the organic solar cell comprises a substrate, an anode, an anode modification layer, an organic solar cell active layer based on oligomer electron acceptors, a cathode modification layer, and a cathode arranged sequentially.

[0020] In a further preferred embodiment, the organic solar cell has a glass substrate; an ITO anode; a PEDOT:PSS anode modification layer; a PDINN cathode modification layer; and Ag anode.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The oligomeric electron acceptor of the present invention has a broadened spectral absorption range, optimized energy level structure and good non-halogen solution processing performance, which can significantly improve the photoelectric conversion efficiency of organic solar cells. Moreover, the preparation method of the oligomeric electron acceptor is simple and efficient. The present invention provides ideas for the development of high-efficiency, high-stability and green solution-processable organic solar cells, and has broad application prospects in the fields of flexible electronics and building-integrated photovoltaic systems.

[0023] (2) Oligomeric electron acceptor materials with oligoethylene glycol side chains introduced into the conjugated bridge structure. Due to the introduction of these side chains, good solution processability in non-halogen solvents is achieved. Furthermore, two different ends can be introduced using a simple method to construct an asymmetric structure. The variability of the electron-withdrawing ends allows for energy level structure modulation, thus enabling excellent optimization of material properties. Based on this molecular design concept, the spectral absorption range is broadened, and the LUMO (Lowest Unoccupied Molecular Orbital) energy level is enhanced, resulting in a good balance between photovoltage, photocurrent, and fill factor in the cell. Therefore, organic solar cells based on D18:L8-BO:DTOCl can achieve a high open-circuit voltage of up to 0.934V and a PCE of 19.04%. Attached Figure Description

[0024] Figure 1 The current-voltage curves of the organic solar cells prepared in Comparative Example 1, Example 2 and Example 5 under illumination are shown.

[0025] Figure 2 The external quantum efficiency-wavelength curves are for the organic solar cells prepared in Examples 2 and 5.

[0026] Figure 3 The UV absorption spectra of the active layer films prepared by D18 film, PM6 film, L8-BO film, DTCl film, DTOCl film, L8-BO:DTCl film, L8-BO:DTOCl film, and Comparative Example 1, Example 2 and Example 5 are shown. Detailed Implementation

[0027] The present invention will be further illustrated below with reference to the embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] Below are two specific synthetic routes for the oligomeric electron acceptors DTOCl and DTCl (where compounds a, f, g, c, and d are commercially available products purchased from the manufacturer).

[0029] The specific synthesis steps of oligomeric electron acceptors DTOCl and DTCl are as follows:

[0030] (1) Synthesis of DTOCl

[0031] Under nitrogen protection and in an ice-water bath, 5 ml of DMF (N,N-dimethylformamide) was injected into a two-necked flask, followed by a slow injection of 2 ml of POCl3. The reaction was allowed to proceed for half an hour. Compound a was dissolved in 1,2-dichloroethane (DCE) and added to the two-necked flask. The reaction mixture was refluxed at 69°C for 10 hours. After the reaction was stopped and cooled to room temperature, the mother liquor was added to a 500 ml beaker and hydrolyzed with potassium acetate solution. Extraction and separation were then performed using dichloromethane. Column purification (eluent: petroleum ether:dichloromethane = 1:1, v / v) yielded an orange oily compound b in 85% yield. The reaction equation is shown below:

[0032]

[0033] Compounds b, c, and d were dissolved in toluene in a reaction flask with stirring at room temperature. Boron trifluoride diethyl ether was slowly added dropwise, turning the solution purple-red. After 15 minutes, acetic anhydride was slowly added dropwise, turning the solution blue-purple. The reaction was continued at room temperature for 3 hours. After the reaction was stopped, the solution was added to methanol solution for precipitation, and the resulting black solid was filtered. The solid was purified by column chromatography (eluent: petroleum ether:dichloromethane = 3:2, v / v) to give the black solid compound e in 40% yield. The reaction equation is shown below:

[0034]

[0035] Compounds e and f, along with catalysts Pd(dba)3 and P(o-tol)3, were dissolved in toluene in a reaction flask. Under nitrogen protection, the reactants were refluxed at 100°C for 4 hours. After the reaction was stopped, the mixture was added to a methanol solution for precipitation, and the resulting black solid was filtered off. The product was purified by column chromatography (eluent: dichloromethane) to give a black solid product, DTOCl, in 70% yield. The reaction equation is shown below:

[0036]

[0037] The characterization results of the oligomeric electron acceptor DTOCl are as follows: 1 H NMR(500MHz, CDCl3)δ9.12(s,2H),8.72(d,J=8.3Hz,2H),8.09(d,J=2.3Hz,4H),7.99–7.93(m,4H),7.75(s,2H),7.59(s, 2H),4.79–4.70(m,8H),3.13(d,J=7.5Hz,4H),3.00(d,J=7.4Hz,4H),2.11(t,J=7.0Hz,10H),1.47–0.65(m,268H).calcd for C 232 H 310 Cl4N 12 O14 S 12 ,4017.62.

[0038] (2) Synthesis of DTCl

[0039] Compounds e and g, along with catalysts Pd(dba)3 and P(o-tol)3, were dissolved in toluene in a reaction flask. Under nitrogen protection, the reactants were refluxed at 100°C for 4 hours. After the reaction was stopped, the mixture was added to a methanol solution for precipitation, and the resulting black solid was filtered. The product, DTCl, was purified by column chromatography (eluent: dichloromethane) to give a black solid product, DTCl, in 73% yield. The reaction equation is shown below:

[0040]

[0041] The characterization results of the oligomeric electron acceptor DTCl are as follows: 1 H NMR (500MHz, CDCl3) δ9.06(s,2H),8.68(d,J=8.2Hz,2H),8.14(s,2H),7.94(d,J=7.3Hz,4H),7.85(d,J=8.2Hz,2H),7.78(s,2H),7.48(d, J=3.8Hz,2H),7.32(d,J=3.8Hz,2H),4.75(dd,J=16.8,7.6Hz,8H),3.03(dd,J=15.7,8.5Hz,8H),2.14(s,12H),1.44–0.65(m,236H).calcd for C 218 H 282 Cl4N 12 O6S 12 ,3693.25.

[0042] Example 1

[0043] The transparent conductive glass with striped ITO (anode) etched on the surface was cleaned by ultrasonic oscillation with cleaning agent, deionized water, acetone and isopropanol in sequence, dried and then treated with ultraviolet ozone for 15 min; then a 20 nm thick layer of PEDOT:PSS was spin-coated on the conductive glass surface at a speed of 4500 rpm, and then annealed at 150℃ for 20 min. Next, the sample was transferred to a glove box, and a mixed solution containing D18, L8-BO, and DTOCl was spin-coated into a film. The total concentration of L8-BO and DTOCl was 3.5 mg / mL relative to the mass concentration of D18, and the mass ratio of D18, L8-BO, and DTOCl was 1:1.2:0.1. The solvent for the mixed solution was chloroform. The spin-coating speed was 2500 rpm, and the spin-coating time was 30 s, resulting in a 100 nm thick film. This film was then heat-annealed at 80 °C for 10 min to obtain the active layer. A 5 nm thick PDINN transport layer was then spin-coated onto the active layer using a 1 mg / mL PDINN methanol solution. Finally, a 100 nm thick Ag electrode (cathode) was deposited using an evaporator, resulting in an effective area of ​​4 mm². 2 Organic solar cells.

[0044] At a light intensity of 100mW / cm 2 Under AM1.5 simulated sunlight irradiation, the current-voltage curve of the device was tested, yielding an open-circuit voltage of 0.925V and a short-circuit current density of 25.51mA / cm². 2 The fill factor is 80.00 and the power conversion efficiency (PCE) is 18.71%.

[0045] Example 2

[0046] The transparent conductive glass with striped ITO (anode) etched on the surface was cleaned by ultrasonic oscillation with cleaning agent, deionized water, acetone and isopropanol in sequence, dried and then treated with ultraviolet ozone for 15 min; then a 20 nm thick layer of PEDOT:PSS was spin-coated on the conductive glass surface at a speed of 4500 rpm, and then annealed at 150℃ for 20 min. Next, the sample was transferred to a glove box, and a mixed solution containing D18, L8-BO, and DTOCl was spin-coated into a film. The total concentration of L8-BO and DTOCl was 4.5 mg / mL relative to the mass concentration of D18, and the mass ratio of D18, L8-BO, and DTOCl was 1:1.2:0.1. The solvent for the mixed solution was chloroform. The spin-coating speed was 2500 rpm, and the spin-coating time was 30 s, resulting in a 100 nm thick film. This film was then heat-annealed at 80 °C for 10 min to obtain the active layer. A 5 nm thick PDINN transport layer was then spin-coated onto the active layer using a 1 mg / mL PDINN methanol solution. Finally, a 100 nm thick Ag electrode (cathode) was deposited using an evaporator, resulting in an effective area of ​​4 mm². 2 Organic solar cells.

[0047] At a light intensity of 100mW / cm 2 Under AM1.5 simulated sunlight irradiation, the current-voltage curve of the device was tested, yielding an open-circuit voltage of 0.934V and a short-circuit current density of 25.76mA / cm². 2 The fill factor is 78.93 and the power conversion efficiency (PCE) is 18.76%.

[0048] Example 3

[0049] The transparent conductive glass with striped ITO (anode) etched on the surface was cleaned by ultrasonic oscillation with cleaning agent, deionized water, acetone and isopropanol in sequence, dried and then treated with ultraviolet ozone for 15 min; then a 20 nm thick layer of PEDOT:PSS was spin-coated on the conductive glass surface at a speed of 4500 rpm, and then annealed at 150℃ for 20 min. Next, the sample was transferred to a glove box, and a mixed solution containing PM6, BTP-eC9, and DTOCl was spin-coated into a film. The total concentration of PM6, BTP-eC9, and DTOCl was 16.5 mg / mL, and the mass ratio of PM6, BTP-eC9, and DTOCl was 1:1.2:0.05. The mixed solution included the additive 3,5-dichlorobromobenzene, and the solvent was chloroform. The concentration of 3,5-dichlorobromobenzene was 10 mg / mL. The spin-coating speed was 2500 rpm, and the spin-coating time was 30 s, resulting in a 100 nm thick film. This film was then heat-annealed at 80 °C for 10 min to obtain the active layer. A 5 nm thick PDINN transport layer was then spin-coated onto the active layer using a 1 mg / mL PDINN methanol solution. Finally, a 100 nm thick Ag electrode (cathode) was deposited using an evaporator, resulting in an effective area of ​​4 mm². 2 Organic solar cells.

[0050] At a light intensity of 100mW / cm 2 Under AM1.5 simulated sunlight irradiation, the current-voltage curve of the device was tested, yielding an open-circuit voltage of 0.867V and a short-circuit current density of 27.41mA / cm². 2 The fill factor is 78.50 and the power conversion efficiency (PCE) is 18.65%.

[0051] Example 4

[0052] The transparent conductive glass with striped ITO (anode) etched on the surface was cleaned by ultrasonic oscillation with cleaning agent, deionized water, acetone and isopropanol in sequence, dried and then treated with ultraviolet ozone for 15 min; then a 20 nm thick layer of 2PACz (0.3 mg / mL ethanol solution) was spin-coated on the conductive glass surface at 2500 rpm, and then annealed at 90 °C for 10 min. Next, the sample was transferred to a glove box, and a mixed solution containing D18, L8-BO, and DTOCl was spin-coated into a film. The total concentration of L8-BO and DTOCl was 4.5 mg / mL relative to the mass concentration of D18, and the mass ratio of D18, L8-BO, and DTOCl was 1:1.2:0.1. The solvent for the mixed solution was chloroform. The spin-coating speed was 2500 rpm, and the spin-coating time was 30 s, resulting in a 100 nm thick film. This film was then heat-annealed at 80 °C for 10 min to obtain the active layer. A 5 nm thick PDINN transport layer was then spin-coated onto the active layer using a 1 mg / mL PDINN methanol solution. Finally, a 100 nm thick Ag electrode (cathode) was deposited using an evaporator, resulting in an effective area of ​​4 mm². 2 Organic solar cells.

[0053] At a light intensity of 100mW / cm 2 Under AM1.5 simulated sunlight irradiation, the current-voltage curve of the device was tested, yielding an open-circuit voltage of 0.934V and a short-circuit current density of 25.88mA / cm². 2 The fill factor is 78.76 and the power conversion efficiency (PCE) is 19.04%.

[0054] Example 5

[0055] The transparent conductive glass with striped ITO (anode) etched on the surface was cleaned by ultrasonic oscillation with cleaning agent, deionized water, acetone and isopropanol in sequence, dried and then treated with ultraviolet ozone for 15 min; then a 20 nm thick layer of PEDOT:PSS was spin-coated on the conductive glass surface at a speed of 4500 rpm, and then annealed at 150℃ for 20 min. Next, the sample was transferred to a glove box, and a mixed solution containing D18, L8-BO, and DTCl was spin-coated into a film. The total concentration of L8-BO and DTCl was 4.5 mg / mL relative to the mass concentration of D18, and the mass ratio of D18, L8-BO, and DTCl was 1:1.2:0.1. The solvent for the mixed solution was chloroform. The spin-coating speed was 2500 rpm, and the spin-coating time was 30 s, resulting in a 100 nm thick film. This film was then heat-annealed at 80 °C for 10 min to obtain the active layer. A 5 nm thick PDINN transport layer was then spin-coated onto the active layer using a 1 mg / mL PDINN methanol solution. Finally, a 100 nm thick Ag electrode (cathode) was deposited using an evaporator, resulting in an effective area of ​​4 mm². 2 Organic solar cells.

[0056] At a light intensity of 100mW / cm 2 Under AM1.5 simulated sunlight irradiation, the current-voltage curve of the device was tested, yielding an open-circuit voltage of 0.931V and a short-circuit current density of 25.98mA / cm². 2 The fill factor is 78.48 and the power conversion efficiency (PCE) is 18.98%.

[0057] Comparative Example 1

[0058] Transparent conductive glass with striped ITO (anode) etched on its surface was sequentially cleaned with a cleaning agent, deionized water, acetone, and isopropanol via ultrasonic vibration, dried, and then treated with UV ozone for 15 min. A 20 nm thick layer of PEDOT:PSS was then spin-coated onto the conductive glass surface at 4500 rpm, followed by annealing at 150 °C for 20 min. Next, the sample was transferred to a glove box, and a mixed solution containing D18, L8-BO, and DTOCl was spin-coated to form a film. The total concentration of L8-BO was 4.5 mg / mL relative to the mass concentration of D18, the mass ratio of D18 to L8-BO was 1:1.2, the solvent of the mixed solution was chloroform, the spin-coating speed was 2500 rpm, and the spin-coating time was 30 s, resulting in a 100 nm thick film. This film was then thermally annealed at 80 °C for 10 min to obtain the active layer. Finally, a 5 nm thick PDINN transport layer was spin-coated onto the active layer using a 1 mg / mL PDINN methanol solution. Finally, a 100nm thick Ag electrode (cathode) was deposited using a vapor deposition apparatus, resulting in an effective area of ​​4mm².2 Organic solar cells.

[0059] At a light intensity of 100mW / cm 2 Under AM1.5 simulated sunlight irradiation, the current-voltage curve of the device was tested, yielding an open-circuit voltage of 0.909V and a short-circuit current density of 26.02mA / cm². 2 The fill factor is 78.27 and the power conversion efficiency (PCE) is 18.35%.

[0060] Comparative Example 2

[0061] Transparent conductive glass with striped ITO (anode) etched on its surface was sequentially cleaned with a cleaning agent, deionized water, acetone, and isopropanol via ultrasonic vibration, dried, and then treated with UV ozone for 15 min. A 20 nm thick layer of PEDOT:PSS was then spin-coated onto the conductive glass surface at 4500 rpm, followed by annealing at 150 °C for 20 min. Next, the sample was transferred to a glove box, and a mixed solution containing D18 and DTCl was spin-coated to form a film. The total concentration of DTCl was 4.5 mg / mL relative to the mass concentration of D18, the mass ratio of D18 to DTCl was 1:1.2, the solvent of the mixed solution was chloroform, the spin-coating speed was 2500 rpm, and the spin-coating time was 30 s, resulting in a 100 nm thick film. This film was then thermally annealed at 80 °C for 10 min to obtain the active layer. Finally, a 5 nm thick PDINN transport layer was spin-coated onto the active layer using a 1 mg / mL PDINN methanol solution. Finally, a 100nm thick Ag electrode (cathode) was deposited using a vapor deposition apparatus, resulting in an effective area of ​​4mm². 2 Organic solar cells.

[0062] At a light intensity of 100mW / cm 2 Under AM1.5 simulated sunlight irradiation, the current-voltage curve of the device was tested, yielding an open-circuit voltage of 1.025V and a short-circuit current density of 6.63mA / cm². 2 The fill factor is 45.11 and the power conversion efficiency (PCE) is 3.06%.

[0063] Sample Analysis

[0064] Figure 1 and Figure 2 The figures show the current-voltage curves and external quantum efficiency-wavelength curves of organic solar cells under illumination, respectively, and the results demonstrate the validity of the data.

[0065] Figure 3The ultraviolet absorption spectra of the D18 film, PM6 film, L8-BO film, DTCl film, DTOCl film, L8-BO:DTCl film, L8-BO:DTOCl film, and the active layer films prepared in Comparative Examples 1, 2 and 5 are shown to demonstrate that the ternary system exhibits complementary absorption spectra, which improves the photon capture capability.

[0066] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An active layer for an organic solar cell based on oligomeric electron acceptors, characterized in that, It includes a polymeric electron donor material and two electron acceptor materials, one of which is an A-DA'DA type electron acceptor material, and the other is an oligomeric electron acceptor. The structural formula of the oligomeric electron acceptor is shown in any of the following formulas:

2. The organic solar cell active layer based on oligomer electron acceptors according to claim 1, characterized in that, The polymer electron donor material is D18 or PM6, and the A-DA'DA type electron acceptor material is L8-BO or BTP-eC9.

3. The organic solar cell active layer based on oligomer electron acceptors according to claim 1, characterized in that, In the organic solar cell active layer based on oligomer electron acceptors, the mass ratio of polymer electron donor material, A-DA'DA type electron acceptor material and oligomer electron acceptor is 1:1.2:0.05~0.

1.

4. The organic solar cell active layer based on oligomer electron acceptors according to claim 1, characterized in that, An active layer solution comprising a polymer electron donor material, an A-DA'DA type electron acceptor material, and an oligomeric electron acceptor was prepared. The active layer solution was spin-coated into a film with a thickness of 50–300 nm, and after annealing, an organic solar cell active layer based on oligomeric electron acceptors was obtained.

5. The organic solar cell active layer based on oligomer electron acceptors according to claim 4, characterized in that, The active layer solution also includes the additive 3,5-dichlorobromobenzene, which volatilizes after annealing.

6. The organic solar cell active layer based on oligomer electron acceptors according to claim 4, characterized in that, The annealing temperature is 80–200℃, and the annealing time is 5–30 min.

7. An organic solar cell, characterized in that, The active layer of an organic solar cell based on oligomer electron acceptors as described in any one of claims 1-6.

8. The organic solar cell according to claim 7, characterized in that, The organic solar cell comprises a substrate, an anode, an anode modification layer, an organic solar cell active layer based on oligomer electron acceptors, a cathode modification layer, and a cathode arranged sequentially.

9. The organic solar cell according to claim 8, characterized in that, In the organic solar cell described above, the substrate is glass; the anode is ITO; the anode modification layer is PEDOT:PSS or 2PACz; the cathode modification layer is PDINN; and the cathode is Ag.

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