D-A Type Fused-Ring Perylene Diimide Interface Materials and Applications

Abstract

The present invention relates to a D-A type polycyclic perylene diimide interfacial material and its application. The interfacial material has the following general chemical structure formula: The D-A type perylene diimide interfacial material provided by the present invention is prepared through a simple and efficient coupling reaction, and has the characteristics of self-assembly, self-doping, good film-forming properties, high electrical conductivity, and thick film processability. As an efficient cathode modification interfacial material, it can be applied to organic photovoltaic cells, which can effectively reduce the energy level barrier, lower the energy loss, enhance the charge transport performance, and thus strengthen the energy conversion efficiency and stability of the device. This type of interfacial material is applicable to various organic photovoltaic cells with high-efficiency active layers.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic cell materials, and particularly relates to an interfacial material for organic photovoltaic cells, especially a D-A type polycyclic perylene diimide interfacial material. In addition, the present invention also relates to a preparation method of the foregoing interfacial material and its application in organic photovoltaic cells. Background Art

[0002] As an efficient, clean and sustainable third-generation photovoltaic cell technology, organic solar cells have the advantages of low cost, light weight, solution processability, large-area thick film preparation and application on flexible substrates, attracting extensive attention from scientific researchers in the photovoltaic field. In recent years, with the rapid development of organic solar cells, they show great application potential in the fields of flexible electronics, building-integrated photovoltaics and indoor photovoltaics. With the continuous innovation of polymer donors and non-fullerene small molecule acceptors, the efficiency of organic solar cells has been continuously improved, and interfacial materials play a key role in strengthening interfacial contact, charge transport and device stability. Compared with organic active layer materials such as donors and acceptors, the development of organic interfacial materials lags behind. The development of organic interfacial materials in organic solar cells faces several research challenges: 1. Organic interfacial materials exhibit poor thin film morphology and solid-state aggregation state, resulting in an increase in the thickness of the interfacial layer film and a significant decrease in interfacial performance; 2. Organic interfacial materials exhibit low charge transport performance and conductivity; 3. Organic interfacial materials also have problems of stability and production cost; 4. There are few types of organic interfacial materials with excellent interfacial performance and universal applicability to be developed. The above key problems limit the subsequent development of organic interfacial materials and at the same time affect the commercialization process of organic solar cells.

[0003] In view of the above technical problems existing in the prior art, on the basis of our previous work, we invented a D-A-D type polycyclic aromatic imide interfacial material (application number: 202310669869.4). This patented technology creatively developed a class of polycyclic aromatic imide small molecule cathode interfacial materials by combining the advantages of polycyclic aromatic diimides and conjugated zwitterionic units, which can to a certain extent solve the problems restricting the application of organic photovoltaic interfacial materials such as high thickness sensitivity, low conductivity and poor stability. However, its disadvantages are that the structure of the material is complex, the synthesis difficulty is high, and the product performance needs to be further improved. Summary of the Invention

[0004] Based on our above-mentioned previous work, the present invention provides a small molecule cathode interface material of polycyclic aromatic imide with improved structure, specifically a D-A type perylene diimide interface material with self-assembly, self-doping, high conductivity, and good film-forming properties. Among them, self-assembly and good film-forming properties are beneficial to adjusting the aggregation state and film morphology, and promoting more regular and orderly molecular arrangement; the polycyclic conjugated backbone and self-doping properties are beneficial to improving the conductivity and charge transport properties of the material; the combination of perylene diimide and dimethylaminopropyl fluorene conjugated backbone can better enhance the stability of the material and reduce the material cost. Therefore, this type of interface material can solve the key problems faced by organic interface materials, and can improve the device efficiency and stability when applied to organic solar cells, and it is expected to obtain a class of efficient and universal organic interface materials.

[0005] The structural general formula Ⅰ of a D-A type polycyclic perylene diimide interface material provided by the present invention is as follows:

[0006]

[0007] X is O, S, Se or SO2;

[0008] Y is an H element or a halogen element;

[0009] R1 is a C1-C 12 linear alkane, a C1-C 12 branched alkane, where n is 1, 2, 3 or 4, and R3 is H, C1-C 12 linear alkane, R4 is H, CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, phenyl or benzyl, and R5 is H, C1-C 12 linear alkane;

[0010] R2 is any one of the following groups:

[0011]

[0012] where n is 1, 2, 3 or 4, and the Z anion is Cl - 、Br - or I - ;

[0013] The synthesis method of the above D-A type polycyclic perylene diimide interface material is as follows:

[0014]

[0015] X is O, S, Se or SO2;

[0016] Y is an H element or a halogen element;

[0017] R1 is C1-C 12 linear alkane, C1-C 12 branched alkane, where n is 1, 2, 3 or 4, and R3 is H, C1-C 12 linear alkane, R4 is H, CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, phenyl or benzyl, and R5 is H, C1-C 12 linear alkane;

[0018] R2 is any one of the following groups:

[0019]

[0020] where n is 1, 2, 3 or 4, and the Z anion is Cl - , Br - or I-;

[0021] The D-A type polycyclic perylene diimide interfacial material of the present invention is suitable as an efficient and universal cathode interfacial material, which can improve interfacial contact, modify the work function of the metal electrode, balance carrier transport, realize a significant improvement in the energy conversion efficiency and stability of the organic photovoltaic cell, and can be used to prepare organic photovoltaic cells with different active layer materials.

[0022] A specific application example is to use the D-A type polycyclic perylene diimide interfacial material of the present invention to form a cathode interfacial layer for an organic solar cell device. Among them, the specific preparation process of the cathode interfacial layer is: dissolving the D-A type polycyclic perylene diimide interfacial material in an alcohol solvent, preparing the cathode interfacial layer by a solution processing method, and then preparing the organic solar cell device. The solvent is one or more of methanol, ethanol, isopropanol, trifluoroethanol or acetic acid. Since the D-A type polycyclic perylene diimide interfacial material provided by the present invention can be dissolved in most organic solvents, it has good film-forming and processing properties.

[0023] A further preferred scheme is that the film thickness of the D-A type polycyclic perylene diimide interfacial material is 5-50 nm.

[0024] A further more preferred scheme is that the electron donor material of the organic active layer of the organic solar cell is PM6, D18 or other organic electron donor materials, and the electron acceptor material is Y6, L8-BO or other organic electron acceptor materials.

[0025] The molecular structures of PM6, D18, Y6, and L8-BO used in the present invention are shown as follows:

[0026]

[0027] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0028] (1) By combining the advantages of polycyclic perylene diimide and conjugated zwitterionic units, the present invention has successfully developed a high-conductivity polycyclic perylene diimide cathode interface material, which solves the key problems restricting the field of organic photovoltaic interfaces, such as high thickness sensitivity, low conductivity, and poor stability. Through the separate regulation and optimization of the polycyclic center, halogen substitution, ionic unit, and side chain engineering, the obtained D-A type polycyclic perylene diimide cathode interface material has the advantages of self-assembly, self-doping, high conductivity, and good film-forming properties. Applying it to large-area thick-film organic battery modules and indoor photovoltaic devices can improve the battery efficiency and stability.

[0029] (2) The D-A type polycyclic perylene diimide interface material of the present invention has good solubility and film-forming properties, suitable molecular energy levels and high conductivity. At the same time, it can improve the interface contact and modify the work function of the metal electrode, and is expected to increase the effective thickness of the film due to its self-assembly characteristics; the conjugated skeleton of polycyclic perylene diimide and self-doping characteristics improve the conductivity of the film; the conjugated ionic unit structure improves the film-forming properties and stability of the film. Therefore, it can be used to prepare highly efficient organic solar cells and is a cathode interface material with great commercial application potential.

[0030] (3) Compared with the commercial cathode interface material, the D-A type polycyclic perylene diimide interface material of the present invention has the advantages of being insensitive to thickness, high conductivity, and good stability, and has excellent interface performance. Its finished product can be used to prepare large-area thick-film organic battery modules and indoor photovoltaic devices.

[0031] (4) Compared with the invention patent "D-A-D type polycyclic aromatic imide interface material and its preparation method and application" (application number: 202310669869.4) applied by us in the early stage, the D-A type polycyclic perylene diimide interface material of the present invention has lower synthesis difficulty, relatively easy control in the synthesis process, relatively lower synthesis cost, and more excellent product performance. Description of the Drawings

[0032] Figure 1 1H NMR spectrum of the interface material FPDI1 prepared in Example 1.

[0033] Figure 2 Absorption spectrum of the methanol solution of the interface material FPDI1 prepared in Example 1.

[0034] Figure 3 Electrochemical curve of the interface material FPDI1 prepared in Example 1.

[0035] Figure 4Prepare the current-voltage (J-V) curve graph of the PM6:Y6-based organic solar cell for Example 1.

[0036] Figure 5 Prepare the external quantum efficiency (EQE) curve graph of the PM6:Y6-based organic solar cell for Example 1.

[0037] Figure 6 Prepare the current-voltage (J-V) curve graph of the PM6:L8-BO-based organic solar cell for Example 1.

[0038] Figure 7 Prepare the external quantum efficiency (EQE) curve graph of the PM6:L8-BO-based organic solar cell for Example 1.

[0039] Figure 8 Prepare the current-voltage (J-V) curve graph of the D18:L8-BO-based organic solar cell for Example 1.

[0040] Figure 9 Prepare the external quantum efficiency (EQE) curve graph of the D18:L8-BO-based organic solar cell for Example 1.

[0041] Figure 10 Prepare the 1H NMR spectrum of the interfacial material FPDI2 prepared in Example 2.

[0042] Figure 11 Prepare the absorption spectrum of the methanol solution of the interfacial material FPDI2 prepared in Example 2.

[0043] Figure 12 Prepare the electrochemical curve of the interfacial material FPDI2 prepared in Example 2.

[0044] Figure 13 Prepare the current-voltage (J-V) curve graph of the PM6:Y6-based organic solar cell for Example 2.

[0045] Figure 14 Prepare the external quantum efficiency (EQE) curve graph of the PM6:Y6-based organic solar cell for Example 2.

[0046] Figure 15 Prepare the current-voltage (J-V) curve graph of the PM6:L8-BO-based organic solar cell for Example 2.

[0047] Figure 16 Prepare the external quantum efficiency (EQE) curve graph of the PM6:L8-BO-based organic solar cell for Example 2.

[0048] Figure 17Prepare the current-voltage (J-V) curve graph of the D18:L8-BO based organic solar cell for Example 2.

[0049] Figure 18 Prepare the external quantum efficiency (EQE) curve graph of the D18:L8-BO based organic solar cell for Example 2.

[0050] Figure 19 Prepare the 1H NMR spectrum of the interfacial material FPDI3 obtained in Example 3.

[0051] Figure 20 Prepare the absorption spectrum of the methanol solution of the interfacial material FPDI3 obtained in Example 3.

[0052] Figure 21 Prepare the electrochemical curve of the interfacial material FPDI3 obtained in Example 3.

[0053] Figure 22 Prepare the current-voltage (J-V) curve graph of the PM6:Y6 based organic solar cell for Example 3.

[0054] Figure 23 Prepare the external quantum efficiency (EQE) curve graph of the PM6:Y6 based organic solar cell for Example 3.

[0055] Figure 24 Prepare the current-voltage (J-V) curve graph of the PM6:L8-BO based organic solar cell for Example 3.

[0056] Figure 25 Prepare the external quantum efficiency (EQE) curve graph of the PM6:L8-BO based organic solar cell for Example 3.

[0057] Figure 26 Prepare the current-voltage (J-V) curve graph of the D18:L8-BO based organic solar cell for Example 3.

[0058] Figure 27 Prepare the external quantum efficiency (EQE) curve graph of the D18:L8-BO based organic solar cell for Example 3. Detailed implementation manners

[0059] The following combines the technical solutions and the drawings to describe in detail the implementation manners of the present invention. It should be noted that the present invention is illustrated by the following examples but not limited thereto. Unless otherwise specified, all parts and percentages are by weight. In addition, the solvents and small molecule intermediates used in the following examples are purchased from Anhui Zesheng Technology Co., Ltd. (Annajie Chemistry) and used directly without further purification before use.

[0060] Example 1

[0061] The structure of the interface material FPDI1 is such that Y is H as described above; is R1 is R2 is When this is the case, the preparation method of the interface material FPDI1 is as follows:

[0062]

[0063] Synthesis of FPDI1. Add the monobrominated polycyclic perylene diimide intermediate (100 mg, 0.11 mmol), the fluorene borate intermediate (62 mg, 0.13 mmol), and tetrakis(triphenylphosphine)palladium (13 mg, 0.011 mmol) into a reactor, then add 2M aqueous potassium carbonate solution (0.4 mL), and use tetrahydrofuran (2 mL) as the solvent. Heat the reaction at 70 °C for 24 hours. Stop the reaction, separate the dichloromethane and water by liquid separation, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 50:1 to obtain a red solid powder. Yield: 70%. 1 H NMR (400 MHz, CDCl3, 25 °C): δ (ppm) = 10.04 (s, 1H), 9.73 (s, 1H), 9.35 (d, 2H), 9.06 (s, 2H), 8.21 - 8.12 (m, 3H), 7.92 (d, 1H), 7.81 (d, 1H), 7.47 - 7.41 (m, 3H), 5.36 (m, 2H), 2.40 - 2.16 (m, 12H), 2.07 (s, 12H), 2.01 - 1.97 (m, 4H), 1.37 - 1.25 (m, 32H), 0.83 (t, 12H); MALDI - TOF - MS: Calcd for C 77 H 92 N4O5, 1152.7068 [M - , found 1152.7061.

[0064] The performance and application of the D - A type polycyclic perylene diimide interface material synthesized in this example are further described in detail below. It should be noted that since the structures of the D - A type polycyclic perylene diimide interface materials prepared by the method of the present invention are very similar and their performances are also relatively close, therefore, the present invention only describes in detail the products obtained from the best examples. However, those skilled in the art can reasonably infer the performances and application effects of other similar products with the structural general formula I claimed in the present invention based on the description of the present invention, and will not be elaborated here.

[0065] Performance testing and application experiments of the FPDI1 interface material.

[0066] a. UV-Vis absorption spectroscopy test

[0067] The instrument model used is the HP8453 UV spectrophotometer from the United States. The product of Example 1 was accurately weighed and diluted into a 1×10 -5 M dichloromethane solution, and tested using a 1 cm glass cuvette at room temperature. The molar extinction coefficient (ε) of this material was calculated using the formula: A = εcb, where A is the absorbance of the maximum absorption peak; c is the molar concentration of the material; b is the thickness of the cuvette used. The optical band gap was calculated by the maximum absorption edge method according to the formula E g = 1240 / λmax eV.

[0068] From the test results, it can be seen that the maximum absorption wavelength of this product is 485 nm, the absorption range is 300 - 600 nm, and its molar absorptivity is calculated to be 8×10 4 M -1 cm -1 , and the optical band gap E g is 2.03 eV, proving that this material has excellent visible light capture performance.

[0069] b. Cyclic voltammetry test

[0070] The instrument model used is the BSA100B / W type electrochemical analysis system. A three-electrode test system was adopted, with a glassy carbon electrode as the working electrode; a saturated calomel electrode as the reference electrode; a platinum wire electrode as the counter electrode; the product of Example 1 was accurately weighed and configured into a 10 mg mL -1 dichloromethane solution, and tetrabutylammonium hexafluorophosphate was added as the electrolyte. Ferrocene was used as the internal standard electrode pair. Referring to the literature, the absolute value of the ferrocene electrode pair relative to vacuum is 4.8 eV. According to the formula E LUMO = -(4.8 + E ox – E 1 / 2 Fc+ / Fc ) eV, the half-wave potential (E onsetre ) of the first reduction peak of the cyclic voltammogram curve of this material was -0.88 V, and the energy level of its LUMO was calculated to be -3.48 eV. Then, according to the formula E HOMO = -(4.8 + E red – E 1 / 2 Fc+ / Fc ) eV, the energy level of its highest occupied molecular orbital (HOMO) was calculated to be -5.75 eV, proving that this material has good redox properties.

[0071] c. Organic solar cell test

[0072] Fabrication of the battery: The ITO substrate was ultrasonically cleaned successively with ethanol, acetone, and ultrapure water; after purging with nitrogen, it was treated with ozone for 30 minutes; a diluted PEDOT:PSS solution was spin-coated with a thickness of about 30 nm; annealed in air at 150 °C for 15 minutes, and then transferred into a glove box to spin-coat a mixed solution of PM6:Y6, PM6:L8-BO, and D18:L8-BO with a thickness of about 100 nm; spin-coated with FPDI1 methanol solutions of different concentrations with a thickness of 5 - 50 nm; the spin-coated substrate was transferred into a vacuum evaporation chamber, and when the vacuum reached 1×10 - 4 Pa, a silver electrode (100 nm) was evaporated.

[0073] Battery performance testing method and process: All batteries were not encapsulated and their performance was tested in a glove box filled with nitrogen. After obtaining the batteries, their J-V curves and EQE curves were measured, that is Figures 4 to 9 . Among them, the J-V curve was measured using a ZolixSolar IV-150A-ZZU system, and the photocurrent was measured using a Zolix-HPS-300XA solar simulator under an AM 1.5G illumination of 100 mW cm -2 , and the light intensity was calibrated using a Zolix QE-B1 silicon-based solar cell. The external quantum efficiency (EQE) spectrum was measured using a ZolixSCS10-X150-DSSC-ZZU system. A formal bulk heterojunction organic solar cell was fabricated with a cell structure of ITO / PEDOT:PSS / organic active layer / FPDI1 / Ag, where indium tin oxide (ITO) and metallic silver were used as electrodes, PEDOT:PSS and NDTI1 were used as the anode modification layer and the cathode modification layer, and the organic active layer was prepared by blending the efficient electron donor PM6 or D18 with the electron acceptor Y6 or L8-BO.

[0074] It can be seen from Figures 4 to 9 that FPDI1, as a cathode interface modification layer, has good interface properties in organic solar cells with different active layers. Compared with the existing cathode interface materials reported in the literature, FPDI1 can simultaneously maintain a high short-circuit current density and fill factor, which is due to the fact that FPDI1 has a large fused-ring ladder conjugated plane, good self-doping properties, and self-assembly characteristics.

[0075] Table 1 lists the best performance parameters of organic solar cells based on different active layers, and Table 2 lists the best performance parameters of organic solar cells based on the PM6:Y6 active layer after applying FPDI1 cathode interface layers with different thicknesses. It can be seen from Tables 1 and 2 that organic solar cells with different active layers all exhibit good photovoltaic performance. When the thickness of the FPDI1 cathode interface layer reaches 50 nm, the cell still maintains an energy conversion efficiency of more than 70%. These results indicate that this technical means can achieve the preparation of high-conductivity, thickness-insensitive, and highly universal cathode interface materials.

[0076] Table 1

[0077]

[0078] Table 2

[0079]

[0080]

[0081] Example 2

[0082] The structure of the interfacial material FPDI2 is as described above with Y being H; being R1 being R2 being When, the preparation method of the interfacial material FPDI2 is as follows:

[0083]

[0084] Synthesis of FPDI2. Add the monobrominated polycyclic perylene diimide intermediate (100 mg, 0.11 mmol), the fluorene borate intermediate (68 mg, 0.15 mmol), and tetrakis(triphenylphosphine)palladium (24 mg, 0.021 mmol) into the reactor, then add 2M aqueous potassium carbonate solution (0.44 mL), and use tetrahydrofuran (2.2 mL) as the solvent. Heat and react at 70 °C for 24 hours. Stop the reaction, separate the dichloromethane and water by liquid separation, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 50:1 to obtain a red solid powder, yield: 70%. 11H NMR(400MHz, CDCl3, 25℃): δ(ppm) = 9.92(s, 1H), 9.44(s, 1H), 9.27(d, 2H), 9.04 - 8.99(m, 3H), 7.96 - 7.79(m, 4H), 7.47 - 7.39(m, 3H), 5.36(m, 2H), 2.42 - 2.37(m, 4H), 2.25 - 2.21(m, 4H), 2.14 - 2.10(m, 4H), 2.05(s, 12H), 1.70 - 1.68(m, 4H), 1.38 - 1.26(m, 32H), 0.83(t, 12H); MALDI - TOF - MS: Calcd for C 77 H 92 N4O4Se, 1216.6284[M - , found 1216.6273.

[0085] The following are the performance tests and application experiments of the FPDI2 interfacial material.

[0086] a. UV - Vis absorption spectrum test

[0087] The maximum absorption wavelength of FPDI2 is 390 nm, and the absorption range is 300 - 600 nm. Its molar extinction coefficient is calculated to be 7×10 4 M -1 cm -1 , and the optical band gap E g is 2.04 eV, indicating that the material has excellent visible - light capture performance.

[0088] b. Cyclic voltammetry test

[0089] The cyclic voltammogram of the material gives the half - wave potential (E onsetre ) of the first reduction peak as - 0.81 V. The energy level of its LUMO is calculated to be - 3.55 eV, and the energy level of its highest occupied molecular orbital (HOMO) is - 5.82 eV, indicating that the material has good redox properties.

[0090] c. Organic solar cell test

[0091] The battery manufacturing method, performance testing method, and process are the same as those in Example 7. The optimal performance parameters of organic solar cells based on different active layers are listed in Table 3, and the optimal performance parameters of organic solar cells based on the PM6:Y6 active layer with different thicknesses of the FPDI2 cathode interface layer are listed in Table 4. It can be seen from Tables 3 and 4 that this performance is higher than that of FPDI2, and at the same time, it maintains a relatively increased open-circuit voltage, short-circuit current density, and fill factor, and is at a relatively high level among the efficiencies of organic solar cells based on the PM6:Y6, PM6:L8-BO, and D18:L8-BO active layers.

[0092] The experimental data show that using FPDI2 as the cathode modification material to prepare organic solar cells can exhibit excellent photovoltaic performance.

[0093] Table 3

[0094]

[0095] Table 4

[0096]

[0097] Example 3

[0098] The structure of the interfacial material FPDI3 is as described above with Y being H; being R1 being R2 being When, the preparation method of the interfacial material FPDI3 is as follows:

[0099]

[0100] Synthesis of FPDI3. Add the monobrominated polycyclic perylene diimide intermediate (100 mg, 0.11 mmol), the fluorene borate intermediate (66 mg, 0.14 mmol), and tetrakis(triphenylphosphine)palladium (13 mg, 0.011 mmol) into the reactor, then add 2M aqueous potassium carbonate solution (0.44 mL), and use tetrahydrofuran (2.2 mL) as the solvent. Heat the reaction at 70 °C for 24 hours. Stop the reaction, separate the dichloromethane and water by liquid separation, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 50:1 to obtain a red solid powder, and the yield is 74%. 11H NMR(400MHz,CDCl3,25℃):δ(ppm)=8.66 - 8.63(m,4H),8.01(s,2H),7.87 - 7.78(dd,2H),7.61 - 7.56(m,1H),7.49 - 7.47(d,2H),7.40 - 7.38(m,3H),5.20(m,2H),2.25 - 2.07(m,12H),2.01(s,12H),1.89 - 1.83(m,4H),1.38 - 1.24(m,32H),0.83(t,12H); MALDI - TOF - MS: Calcd for C 77 H 92 N4O4S, 1168.6839[M - , found 1168.6832.

[0101] The following are the performance tests and application experiments of the FPDI3 material.

[0102] a. UV - Vis absorption spectrum test

[0103] The maximum absorption wavelength of FPDI2 is 537 nm, and the absorption range is 300 - 600 nm. Its molar extinction coefficient is calculated to be 7×10 4 M -1 cm -1 , and the optical band gap E g is 2.04 eV, indicating that the material has excellent visible - light capture performance.

[0104] b. Cyclic voltammetry test

[0105] The cyclic voltammogram of the material gives the half - wave potential (E onsetre ) of the first reduction peak as - 0.76 eV. The calculated energy level of its LUMO is - 3.60 eV, and the energy level of its highest occupied molecular orbital (HOMO) is - 5.86 eV, indicating that the material has good redox properties.

[0106] c. Organic solar cell test

[0107] The battery fabrication method, performance test method and process are the same as those in Example 7. The best performance parameters of organic solar cells based on different active layers are listed in Table 5, and the best performance parameters of organic solar cells based on the PM6:L8 - BO active layer with different thicknesses of the FPDI3 cathode interface layer are listed in Table 6.

[0108] As can be seen from Tables 5 and 6, the batteries with different active layers all showed good performance and excellent thickness tolerance. When the thickness of FPDI3 reached 20 nm, the battery maintained an energy conversion efficiency of 97.6%; when the thickness reached 50 nm, the battery maintained an energy conversion efficiency of 88%. The test data show that using FPDI3 as the cathode modification material to prepare organic solar cells can also exhibit excellent photovoltaic performance.

[0109] Table 5

[0110]

[0111] Table 6

[0112]

[0113]

[0114] Through the performance testing and application experiments of the FPDI1, FPDI2, and FPDI3 materials synthesized in Examples 1 to 3 of the present invention, it can be clearly seen that the D-A type polycyclic perylene diimide interfacial materials provided by the present invention have the advantages of high conductivity, thickness insensitivity, and good universality. It should be noted that when FPDI2 is used as the cathode interfacial layer, the PM6:Y6 organic solar cell obtains one of the highest device efficiencies in this system; in addition, when FPDI2 is applied to the D18:L8-BO organic solar cell, the highest binary regular organic solar cell efficiency is obtained.

[0115] Example 4

[0116] The structure of the interfacial material FPDI4 is as described above, where Y is F; is R1 is R2 is When, the preparation method of the interfacial material FPDI4 is as follows:

[0117]

[0118] Synthesis of FPDI4. Add the monobromo polycyclic perylene diimide intermediate (100 mg, 0.1 mmol), fluorene borate intermediate (93 mg, 0.13 mmol), and tetrakis(triphenylphosphine)palladium (17 mg, 0.014 mmol) into the reactor, then add 2M aqueous potassium carbonate solution (0.4 mL), and N,N-dimethylformamide (2 mL) as the solvent. Heat the reaction at 90 °C for 24 hours. Stop the reaction, separate the dichloromethane and water by liquid separation, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 50:1 to obtain a red solid powder, yield: 72%. MALDI-TOF-MS: Calcd for C85 H 106 Br2F2N2O8P2S, 1572.5480 [M - , found 1572.5411.

[0119] Example 5

[0120] The structure of the interface material FPDI5 is as described above with Y being Cl; being R1 being R2 being When, the preparation method of the interface material FPDI5 is as follows:

[0121]

[0122] Synthesis of FPDI5. Add the monobrominated polycyclic perylene diimide intermediate (100 mg, 0.083 mmol), the fluorene borate intermediate (111 mg, 0.1 mmol) and tetrakis(triphenylphosphine)palladium (12 mg, 0.01 mmol) into the reactor, then add 2M aqueous potassium carbonate solution (0.3 mL), and N,N-dimethylformamide (1.5 mL) as the solvent. Heat the reaction at 90 °C for 24 hours. Stop the reaction, separate the dichloromethane and water by liquid separation, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 50:1, to obtain a red solid powder, yield: 75%. MALDI-TOF-MS: Calcd for C 121 H 132 Cl2I2N2O6P2S, 2126.6748 [M - , found 2126.6734.

[0123] Example 6

[0124] The structure of the interface material FPDI6 is as described above with Y being H; being R1 being R2 being When, the preparation method of the interface material FPDI6 is as follows:

[0125]

[0126] Synthesis of FPDI6. Add the monobrominated polycyclic perylene diimide intermediate (100 mg, 0.097 mmol), the fluorene borate intermediate (65 mg, 0.13 mmol), and tetrakis(triphenylphosphine)palladium (12 mg, 0.01 mmol) into a reactor, then add 2M aqueous potassium carbonate solution (0.4 mL), and use tetrahydrofuran (2 mL) as the solvent. Heat the reaction at 70 °C for 24 hours. Stop the reaction, separate the dichloromethane and water by liquid separation, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 50:1 to obtain a red solid powder with a yield of 71%. MALDI-TOF-MS: Calcd for C 83 H 92 N8O6S, 1328.6861[M - , found 21328.6845.

[0127] Comparative Example 1

[0128] The following is a detailed description of the technological progress of the D-A type polycyclic perylene diimide interfacial material of the present invention compared with the D-A-D type organic cathode interfacial material synthesized in our previous work through comparative examples. Here, the D-A-D type organic cathode interfacial material NDTI1 is taken as an example for detailed description. The structural formula of the NDTI1 material is as follows. For its synthesis method, refer to the invention patent "D-A-D type polycyclic aromatic imide interfacial material and its preparation method and application" (Application No.: 202310669869.4) submitted to the State Intellectual Property Office of China in our previous work.

[0129]

[0130] Table 7 shows the device performance of NDTI1 when paired with different active layers, and Table 8 shows the battery performance of NDTI1 at different thicknesses. From the data in Table 7 and Table 8, combined with the performance test data of the products in Examples 1 to 3 of the present invention, it can be seen that the battery efficiency of FPDI1, FPDI2, and FPDI3 under different active layers is higher than that of NDTI1. Especially for PFDI2, this is mainly due to the improved conductivity. In addition, FPDI3 still maintains efficiencies of 97% and 87% at thicknesses of 20 and 50 nm, which are much higher than the efficiencies of 87% and 72% maintained by NDTI1 at thicknesses of 20 and 50 nm, proving that FPDI3 has significantly improved thickness tolerance. It can be seen that the material performance of the D-A type polycyclic perylene diimide interfacial material with improved structure provided by the present invention is significantly higher than that of the D-A-D type polycyclic aromatic imide interfacial material after application.

[0131] Table 7

[0132]

[0133] Table 8

[0134]

Claims

1. A D-A type fused-ring perylene diimide interfacial material has a structural general formula shown in formula (1): X is O, S, Se or SO2; Y is an H element or a halogen element; R1 is R2 is 2. Application of the D-A type fused-ring perylene diimide interfacial material described in claim 1 as a cathode interfacial material.

3. The application according to claim 2, characterized in that The D-A type fused-ring perylene diimide interfacial material is made into a cathode interfacial layer for an organic solar cell device.

4. The application according to claim 3, characterized in that, The preparation process of the cathode interfacial layer is as follows: The D-A type fused-ring perylene diimide interfacial material is dissolved in an alcohol solvent, and the cathode interfacial layer is obtained by a solution processing method.

5. The application according to claim 4, characterized in that, The solvent uses at least one of methanol, ethanol, isopropanol, and trifluoroethanol.

6. The application according to claim 4, wherein The film thickness of the D-A type fused-ring perylene diimide interfacial material is 5-50 nm.

7. The application according to any one of claims 3 to 6, characterized in that, The electron donor material of the organic active layer of the organic solar cell is PM6 or D18, and the electron acceptor material is Y6 or L8-BO.

Images