D-A-D type fused-ring aromatic imide interfacial material, its preparation method and application

Abstract

The present invention relates to a D-A-D type polycyclic aromatic imide interfacial material, a preparation method thereof and an application thereof. The interfacial material has the following general chemical structure formula: The D-A-D type polycyclic aromatic imide interfacial material is prepared by a simple and efficient coupling reaction. The present invention provides a D-A-D type polycyclic aromatic imide interfacial material that is insensitive to thickness, has high conductivity and good stability. Such molecules can be used as efficient and universal cathode modification interfacial materials, which can effectively improve interfacial contact, regulate the work function of metal electrodes, balance carrier transport performance, improve electron collection efficiency, and finally greatly improve the energy conversion efficiency and stability of organic photovoltaic cells. Such interfacial materials can be used to prepare organic photovoltaic cells with different active layer materials.

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-D type fused-ring aromatic imide 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] With the continuous consumption of fossil energy, developing high-efficiency clean energy is an important way to cope with the energy crisis. In recent years, organic photovoltaic cells have developed rapidly as a research hotspot in clean energy science. Among them, organic photovoltaic cells have shown great application prospects and development potential in the fields of wearable or portable electronic products, building-integrated photovoltaics, and indoor photovoltaics due to their advantages such as low cost, light weight, solution processability, availability of flexible substrates, and large-area thick film preparation. However, the development of organic photovoltaic cells faces several research difficulties: 1) The synthesis of organic interfacial materials is difficult, costly, and not easy to produce on a large scale; 2) The poor aggregation state and film morphology of the interfacial materials result in high thickness sensitivity; 3) The conductivity of the interfacial materials is relatively low; 4) There are few types of highly efficient and universal interfacial materials to be developed. The above key problems limit the development of organic photovoltaic cells. Therefore, there is a need to develop types of highly efficient and universal interfacial materials.

[0003] Aiming at the technical problems of the difficult synthesis, high cost, and not easy large-scale production of organic interfacial materials, Chinese Patent CN 112409356B provides a preparation method of an aromatic imide-based interfacial layer that is simple and feasible and can be prepared on a large scale. The interfacial material provided by this invention, as the interfacial layer in organic / polymer solar cells, uses a high-work-function metal as the cathode, which can improve the device performance, and the side chain of this cathode interfacial material can effectively dope the aromatic group of the material, with high conductivity. However, it has problems of poor solubility of the interfacial material and film thickness sensitivity. Chinese Patent CN 109535078A discloses a naphthalimide derivative, which uses an n-type naphthalimide as the basic unit, and the naphthalimide is connected by an ethylene bond, an acetylene bond, or an aromatic compound, and the naphthalimide end contains a strongly polar water / alcohol-soluble group. The naphthalimide derivative molecules provided by this invention have excellent solubility in environmentally friendly solvents and can improve the electron transport performance and transport efficiency. However, its disadvantage is that the conjugated plane of this interfacial material is relatively small, resulting in low conductivity.

[0004] In view of the technical problems that many currently efficient organic cathode interface materials result in poor stability and relatively low photovoltaic performance of the prepared battery products, Chinese Patent CN 114478545A discloses a pyrene diimide compound, its preparation method, a cathode interface material, and a semiconductor device. Using the pyrene diimide compound to prepare a cathode interface material can exhibit good film thickness insensitivity and thermal stability, and can form complementary absorption with generally used active layer materials, improving the external quantum efficiency of solar cell devices and enhancing the overall stability of solar cell devices. However, the disadvantage of this inventive method is that the strong crystallinity and poor solubility of the interface material limit the application scope of this type of material. Summary of the Invention

[0005] In view of the above technical problems existing in the prior art, the first object of the present invention is to provide a D-A-D type fused-ring aromatic imide interface material with thickness insensitivity, high conductivity, and good stability.

[0006] The general structural formula Ⅰ of a D-A-D type fused-ring aromatic imide interface material provided by the present invention is as follows:

[0007]

[0008] In formula (Ⅰ), Ar is

[0009] any one of ;

[0010] R1 is a C1-C 12 linear alkane, a C1-C 12 branched alkane, where n is 1, 2, 3, or 4;

[0011] R2 is any one of the following groups:

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

[0013] R3 is H, a C1-C 12 linear alkane;

[0014] R4 is CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, phenyl, or benzyl;

[0015] R5 is H, a C1-C 12 linear alkane.

[0016] In the structure of the D-A-D type polycyclic aromatic imide interfacial material of the present invention, the polycyclic aromatic imide conjugated skeleton structure can improve the conductivity of the thin film, and the conjugated ionic unit structure can effectively improve the film-forming property and stability of the thin film. Through the synergistic effect of the advantages of polycyclic aromatic diimide and conjugated zwitterionic units, controllable adjustment of the polycyclic center, ionic unit and side chain engineering can be achieved. In addition, in the structure of the D-A-D type polycyclic aromatic imide interfacial material of the present invention, the R2 group adopts electron-rich groups containing N or P such as etc., which can increase the intramolecular charge transfer, is beneficial to improving the self-doping effect of the interfacial material, and solves the key problems restricting the organic photovoltaic interface field such as high thickness sensitivity, low conductivity and poor stability of common interfacial materials in the prior art.

[0017] Compared with the commercial cathode interfacial material, the D-A-D type small molecule cathode interfacial material provided by the present invention has the advantages of being insensitive to thickness, high conductivity, good stability, etc., and has good interfacial performance, good solubility, and is easy to be processed into a film, and is suitable for preparing products such as solar cells with high energy conversion efficiency or flexible large-area organic solar cells, etc., and is a potential cathode interfacial material. After double optimization of the molecular structure and device engineering, it is applied to the battery module and indoor photovoltaic device with large-area thick film, and can greatly improve the efficiency and stability of the battery or device.

[0018] The second object of the present invention is to provide a synthesis method for preparing the aforementioned D-A-D type polycyclic aromatic imide interfacial material with mild conditions and simple operation. The specific technical solution is as follows:

[0019] The preparation process of the interfacial material of general formula Ⅰ is as follows:

[0020]

[0021] In the formula is any one of;

[0022] R1 is C1-C 12 linear alkane, C1-C 12 branched alkane, where n is 1, 2, 3 or 4;

[0023] R2 is any one of the following groups:

[0024]

[0025] where n is 1, 2, 3 or 4, and the Z anion is Cl - , Br - or I - [[ID=

[0026] R3 is H, C1-C 12 linear alkane;

[0027] R4 is CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, phenyl or benzyl;

[0028] R5 is H, C1-C 12 linear alkane.

[0029] The preparation method of a D-A-D type polycyclic aromatic imide interface material of the present invention is specifically as follows:

[0030] Using a dibromo polycyclic aromatic imide intermediate and a mono-pinacol borate fluorene derivative as raw materials, their molar ratio is 1:2-5, Pd(PPh3)4 is used as a catalyst, and the molar ratio of the dibromo polycyclic aromatic imide intermediate to the catalyst is 1:0.05-0.2, 0.5-2M K2CO3 is used as a base source, and under the condition of 60-120 °C, stirring reaction is carried out in an organic solvent for 8-24 hours, and a D-A-D type polycyclic aromatic imide interface material of general formula I is obtained through a carbon-carbon coupling reaction.

[0031] Preferably, the organic solvent is selected from one or more of toluene, chlorobenzene, o-dichlorobenzene, tetrahydrofuran, ethylene glycol monomethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone.

[0032] The material prepared by the above method can be separated by conventional methods, such as precipitation and filtration, silica gel column chromatography, solution recrystallization, spray drying, etc.

[0033] The D-A-D type polycyclic aromatic imide interface material of the present invention has mild synthesis conditions and low raw material prices, which is conducive to large-scale production and popularization and application.

[0034] The third object of the present invention is to provide the application of the D-A-D type polycyclic aromatic imide interface material. As an efficient and universal cathode interface material, it can improve interface 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.

[0035] A preferred solution is to use the D-A-D type fused-ring aromatic imide interfacial material to form a cathode interfacial layer for an organic solar cell device. Among them, the specific preparation process of the cathode interfacial layer is as follows: Dissolve the D-A-D type fused-ring aromatic imide interfacial material in an alcohol solvent, and obtain the cathode interfacial layer by solution processing method, and then prepare the organic solar cell device. The solvent is at least one of methanol, ethanol, isopropanol, and trifluoroethanol. Since the D-A-D type fused-ring aromatic imide interfacial material provided by the present invention can be dissolved in conventional organic solvents, it has good processing performance.

[0036] A further preferred solution is that the film thickness of the D-A-D type fused-ring aromatic imide interfacial material is 5-50 nm.

[0037] A further more preferred solution 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.

[0038] The molecular structures of PM6, D18, Y6, and L8-BO used in the present invention are shown as follows:

[0039]

[0040] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0041] (1) The D-A-D type fused-ring aromatic imide interfacial material of the present invention has excellent visible light capture performance. In a specific embodiment, the maximum absorption wavelength of the interfacial material is 350 nm, and the molar extinction coefficient is 5×10 4 M -1 cm -1 , and the optical band gap E g is 2.03 eV.

[0042] (2) The D-A-D type fused-ring aromatic imide interfacial material of the present invention has suitable molecular energy levels. In a specific embodiment, the LUMO energy level of the interfacial material is -3.59 eV, and its highest occupied orbital (HOMO) energy level is estimated to be -5.62 eV, indicating that it has good redox characteristics and is very suitable as a cathode interfacial material.

[0043] (3) The D-A-D type fused-ring aromatic imide interfacial material of the present invention has a ladder-shaped conjugated plane, good self-doping properties and high conductivity. Therefore, as the cathode interfacial layer, it can simultaneously maintain a high short-circuit current density and fill factor.

[0044] (4) The synthesis conditions of the D-A-D type polycyclic aromatic imide interfacial material of the present invention are mild and the raw materials are inexpensive. The synthesized D-A-D type polycyclic aromatic imide interfacial material exhibits high photovoltaic performance in organic solar cells with different organic active layers. In a specific embodiment, when the thickness of the cathode interfacial layer reaches 50 nm, the solar cell using the interfacial material of the present invention still maintains an energy conversion efficiency of more than 70%, indicating that the D-A-D type polycyclic aromatic imide interfacial material prepared by the synthesis method of the present invention has the advantages of high conductivity, insensitivity to thickness, and good universality. Description of the Drawings

[0045] Figure 1 1H NMR spectrum of the interfacial material NDTI1 prepared in Example 1.

[0046] Figure 2 Absorption spectra of the dichloromethane solution and solid film of the interfacial material NDTI1 prepared in Example 1.

[0047] Figure 3 Electrochemical curve of the interfacial material NDTI1 prepared in Example 1.

[0048] Figure 4 Current-voltage (J-V) curve of the PM6:Y6-based organic solar cell prepared in Example 1.

[0049] Figure 5 External quantum efficiency (EQE) curve of the PM6:Y6-based organic solar cell prepared in Example 1.

[0050] Figure 6 Current-voltage (J-V) curve of the PM6:L8-BO-based organic solar cell prepared in Example 1.

[0051] Figure 7 External quantum efficiency (EQE) curve of the PM6:L8-BO-based organic solar cell prepared in Example 1.

[0052] Figure 8 Current-voltage (J-V) curve of the D18:L8-BO-based organic solar cell prepared in Example 1.

[0053] Figure 9 External quantum efficiency (EQE) curve of the D18:L8-BO-based organic solar cell prepared in Example 1.

[0054] Figure 10 Absorption spectra of the dichloromethane solution and solid film of the interfacial material PDTI1 prepared in Example 2.

[0055] Figure 11The electrochemical curve of the interfacial material PDTI1 prepared in Example 2.

[0056] Figure 12 The current-voltage (J-V) curve of the PM6:Y6-based organic solar cell prepared in Example 2.

[0057] Figure 13 The external quantum efficiency (EQE) curve of the PM6:Y6-based organic solar cell prepared in Example 2 Detailed implementation manners

[0058] The implementation manners of the present invention will be described in detail below in combination with the technical solutions and the drawings. 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 were purchased from Anhui Zesheng Technology Co., Ltd. (Anychem Chemical), and were used directly without further purification before use.

[0059] Example 1

[0060] The structure of the interfacial material NDTI1 is as described above, where Ar is is R1 is R2 is When, the preparation method of the interfacial material NDTI1 is as follows:

[0061]

[0062] Synthesis of NDTI1. Add the dibromo fused-ring naphthalimide intermediate (50 mg, 0.04 mmol), the fluorene borate intermediate (48 mg, 0.11 mmol) and tetrakis(triphenylphosphine)palladium (5 mg, 0.004 mmol) into a reactor, then add 2M aqueous potassium carbonate solution (0.5 mL), and tetrahydrofuran (2.5 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 blue solid powder with a yield of 70%. 1 H NMR (400 MHz, CDCl3, 25 °C): δ (ppm) = 8.11 - 8.00 (m, 4H,), 7.73 - 7.71 (m, 4H), 7.45 - 7.39 (m, 8H), 4.38 - 4.35 (m, 4H), 2.20 - 2.08 (m, 40H), 1.25 - 1.19 (m, 90H), 0.83 (t, 12H); MALDI-TOF-MS: Calcd for C 112 H 162N6O4S2, 1719.2099 [M - , found 1719.2091.

[0063] Example 2

[0064] When the structure of the interfacial material PDTI1 is as described above, where Ar is and R1 is R2 is the preparation method of the interfacial material PDTI1 is as follows:

[0065]

[0066] Synthesis of PDTI1. Add the dibrominated polycyclic perylene diimide intermediate (100 mg, 0.078 mmol), the fluorene borate intermediate (92 mg, 0.2 mmol) and palladium tetrakis(triphenylphosphine) (10 mg, 0.008 mmol) into a reactor, then add 2M aqueous potassium carbonate solution (1.2 mL), and use tetrahydrofuran (6 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 = 100:1, obtaining a red solid powder. Yield: 70%. MALDI-TOF-MS: Calcd for C 118 H 150 N6O4S2, 1779.1160 [M - , found 1779.1158.

[0067] Example 3

[0068] When the structure of the interfacial material NDTI2 is as described above, where Ar is and R1 is R2 is the preparation method of the interfacial material NDTI2 is as follows:

[0069]

[0070] Synthesis of NDTI2. Add the dibromo-fused-ring naphthalimide intermediate (100 mg, 0.1 mmol), the fluorene borate intermediate (102 mg, 0.2 mmol) and palladium tetrakis(triphenylphosphine) (12 mg, 0.01 mmol) into a reactor, then add 2M aqueous potassium carbonate solution (1.2 mL), and use tetrahydrofuran (6 mL) as the solvent. Heat the reaction at 70 °C for 24 hours. Stop the reaction, separate the dichloromethane layer from the water layer, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 100:1 to obtain a blue solid powder with a yield of 72%. MALDI-TOF-MS: Calcd for C 94 H 106 N 10 O4Se2, 1598.6729 [M - , found 1598.6711.

[0071] Example 4

[0072] The structure of the interfacial material PDTI2 is as described above, where Ar is is R1 is R2 is When, the preparation method of the interfacial material PDTI2 is as follows:

[0073]

[0074] Synthesis of PDTI2. Add the dibromo-fused-ring perylene diimide intermediate (110 mg, 0.08 mmol), the fluorene borate intermediate (103 mg, 0.16 mmol) and palladium tetrakis(triphenylphosphine) (10 mg, 0.008 mmol) into a reactor, then add 2M aqueous potassium carbonate solution (1.5 mL), and use tetrahydrofuran (7.5 mL) as the solvent. Heat the reaction at 70 °C for 24 hours. Stop the reaction, separate the dichloromethane layer from the water layer, wash with water, dry, remove the solvent, and purify by silica gel column chromatography. The polarity of the eluent is dichloromethane:methanol = 100:1 to obtain a blue solid powder with a yield of 75%. MALDI-TOF-MS: Calcd for C 120 H 154 I4N2O 12 P4S2, 2510.6072 [M - , found 2510.6023.

[0075] Example 5

[0076] The structure of the interfacial material PDTI3 is as described above, where Ar is is R1 is R2 is When, the preparation method of the interface material PDTI3 is as follows:

[0077]

[0078] Synthesis of PDTI3. Add the dibrominated polycyclic perylene diimide intermediate (100 mg, 0.093 mmol), the fluorene borate intermediate (168 mg, 0.19 mmol) and tetrakis(triphenylphosphine)palladium (11 mg, 0.009 mmol) into the reactor, then add 2M aqueous potassium carbonate solution (1.1 mL), and tetrahydrofuran (5.5 mL) as the solvent, heat and react at 70 °C for 24 hours. Stop the reaction, separate 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 = 100:1, and a red solid powder is obtained with a yield of 71%. MALDI-TOF-MS: Calcd for C 160 H 142 Cl4N6O8P4, 2536.8689 [M - , found 2536.8244.

[0079] The performance and application of the D-A-D type polycyclic aromatic imide interface material synthesized by the method of the present invention are further described in detail below through Examples 6 and 7. It should be noted that since the structures of the D-A-D type polycyclic aromatic imide interface materials prepared by the method of the present invention are very similar and their performances are also relatively close, in order to clearly and briefly illustrate the performance and application effects of the materials, Examples 6 and 7 only describe in detail the products prepared in the best Examples 1 and 2 of the present invention respectively. However, those skilled in the art can reasonably infer the performance and application effects of other similar products with the structural general formula I claimed in the present invention based on the best examples of the present invention, which will not be elaborated here.

[0080] Example 6

[0081] This example is a material performance test and application test of the interface material NDTI1 prepared in Example 1.

[0082] a. Ultraviolet-visible absorption spectrum test. The instrument model used is the HP8453 type ultraviolet spectrophotometer of the United States. Accurately weigh the product of Example 1 and dilute it into a 1×10 -5 M dichloromethane solution, and perform the test at room temperature using a 1 cm glass cuvette. The molar extinction coefficient (ε) of this material is 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 is determined by the maximum absorption edge method, according to the formula E g= 1240 / λmax eV for calculation. The maximum absorption wavelength of this product is 350 nm, and the absorption range is 300 - 680 nm. Calculate its molar extinction coefficient to be 5×10 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.

[0083] b. Cyclic voltammetry test. The instrument model used is the BSA100B / W type electrochemical analysis system. A three - electrode test system is 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; accurately weigh the product of Example 1 and prepare a 10 mg mL -1 dichloromethane solution, and add tetrabutylammonium hexafluorophosphate as the electrolyte. Use ferrocene as the internal standard electrode pair. Referring to the literature, the absolute value of the ferrocene electrode pair relative to vacuum is 5.08 eV. According to the formula E LUMO = -(5.08 + E onsetre ) eV, the cyclic voltammogram of this material gives the half - wave potential (E onsetre ) of its first reduction peak as - 1.49 V. Calculate the energy level of its LUMO to be - 3.59 eV. Then, according to the formula E HOMO = (E LUMO - E g ) eV, estimate the energy level of its highest occupied molecular orbital (HOMO) to be - 5.62 eV, proving that this material has good redox properties.

[0084] c. Organic solar cell test. Fabrication of the cell: The ITO substrate is ultrasonically cleaned successively with ethanol, acetone, and ultrapure water; after purging with nitrogen, it is treated with ozone for 30 minutes; spin - coat a diluted PEDOT:PSS solution with a thickness of about 30 nm; anneal in air at 150 °C for 15 minutes, then enter the glove box and spin - coat a mixed solution of PM6:Y6, PM6:L8 - BO, D18:L8 - BO with a thickness of about 100 nm; spin - coat NDTI1 methanol solutions with different concentrations with a thickness of 3 - 50 nm; transfer the spin - coated substrate into the vacuum evaporation chamber. When the vacuum reaches 1×10 -4 Pa, evaporate the silver electrode (100 nm). Battery performance test method and process: All batteries are not encapsulated, and the performance tests are carried out in a glove box filled with nitrogen. After obtaining the battery, test its J - V curve and EQE curve, that is Figures 4 to 9 . Among them, the J - V curve is measured using the Zolix Solar IV - 150A - ZZU system, and the photocurrent is at 100 mW cm -2Measured under AM 1.5G illumination using a Zolix-HPS-300XA solar simulator, 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 Zolix SCS10-X150-DSSC-ZZU system. A formal bulk heterojunction organic solar cell was fabricated with a cell structure of ITO / PEDOT:PSS / organic active layer / NDTI1 / Ag, where indium tin oxide (ITO) and metallic silver were used as electrodes, PEDOT:PSS and NDTI1 were used as an anode modification layer and a cathode modification layer, and the organic active layer was prepared by blending a highly efficient electron donor PM6 or D18 with an electron acceptor Y6 or L8-BO.

[0085] by Figures 4 to 9 It can be seen that the NDTI1 cathode interface layer has high interfacial performance in organic solar cells with different organic active layers. Compared with the existing cathode interface layers reported in the literature, NDTI1 can simultaneously maintain a high short-circuit current density and fill factor, which is due to the trapezoidal conjugated plane, good self-doping property, and high conductivity of NDTI1.

[0086] Table 1 lists the preferred performance parameters of organic solar cells based on different organic active layers, and Table 2 lists the performance parameters of organic solar cells based on the PM6:Y6 active layer when using different thicknesses of the NDTI1 cathode interface layer. As can be seen from Tables 1 and 2, organic solar cells with different active layers all exhibit high photovoltaic performance, and when the thickness of the NDTI1 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 is easy to prepare a highly efficient cathode interface material with high conductivity, thickness insensitivity, and good universality.

[0087] Table 1

[0088]

[0089] Table 2

[0090]

[0091] Example 7

[0092] This example is a material property test and application test of the interface material NDTI1 prepared in Example 2.

[0093] a. UV-visible absorption spectrum test. The maximum absorption wavelength of PDTI1 is 350 nm, and the absorption range is 300 - 800 nm. Its molar extinction coefficient was calculated to be 6×10 4 M -1 cm -1 , and the optical band gap E gIt is 1.71 eV, proving that the material has excellent visible light capture performance.

[0094] b. Cyclic voltammetry test. The cyclic voltammogram of the material gives the half-wave potential (E onsetre ) of its first reduction peak as -1.21 V. Calculating, the energy level of its LUMO is -3.87 eV, and the energy level of its highest occupied molecular orbital (HOMO) is -5.58 eV, proving that the material has good redox characteristics.

[0095] c. Organic solar cell test. The method of fabricating the cell, the method and process of performance testing are the same as those in Example 6. Table 3 lists the preferred performance parameters of the organic solar cell based on the PM6:Y6 active layer. Although the performance is slightly lower than that of NDTI1, it still maintains a relatively good open-circuit voltage, short-circuit current density and fill factor, and is still at a relatively high level among the organic solar cells based on the PM6:Y6 active layer. The experimental data show that using PDTI1 as the cathode modification layer to fabricate organic solar cells can also exhibit relatively high photovoltaic performance.

[0096] Table 3

[0097]

[0098] The analysis and tests of Examples 6 and 7 fully show that the synthesized D-A-D type fused-ring aromatic imide interfacial material prepared by the method of the present invention has high conductivity, thickness insensitivity and good universality after application. At present, many researchers improve the energy conversion efficiency of normal organic solar cells by developing cathode interfacial materials, and this method is also considered to be one of the most effective means to improve the cell performance. It is worth noting that when using the NDTI1 cathode interfacial layer, the efficiency obtained by the PM6:Y6 organic solar cell is one of the highest efficiencies in this system; in addition, when applying NDTI1 to the D18:L8-BO organic solar cell, the highest efficiency of binary normal organic solar cells is obtained.

Claims

1. A D-A-D type fused-ring aromatic imide interfacial material has a structural general formula shown in Formula (1): In formula (I), Ar is For any one of; R1 is C1-C 12 linear alkane, C1-C 12 branched alkane, where n is 1, 2, 3 or 4; R2 is any one of the following groups: where n is 1, 2, 3 or 4, and the Z anion is Cl - , Br - or I - ; R3 is H, C1-C 12 linear alkane; R4 is CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, phenyl or benzyl; R5 is H, C1-C 12 linear alkane.

2. A preparation method of a D-A-D type fused-ring aromatic imide interfacial material, characterized in that, Under alkaline conditions, a carbon-carbon coupling reaction occurs between a dibromo fused-ring naphthalene (perylene) imide intermediate and a mono-pinacol borate fluorene derivative under catalytic action to synthesize a D-A-D type fused-ring aromatic imide interfacial material. The reaction general formula is: wherein is any one of; R1 is C1 to C 12 linear alkane, C1 to C 12 branched alkane, where n is 1, 2, 3 or 4; R2 is any one of the following groups: where n is 1, 2, 3 or 4, and the Z anion is Cl - , Br - or I - ; R3 is H, C1-C 12 linear alkane; R4 is CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, phenyl or benzyl; R5 is H, C1-C 12 linear alkane; The reaction conditions are: using tetrahydrofuran as the reaction solvent and heating the reaction at 70 °C for 24 hours.

3. The preparation method according to claim 2, wherein, The catalyst used in the preparation process is tetrakis(triphenylphosphine)palladium, and the base is potassium carbonate.

4. The preparation method according to claim 2, wherein, The synthesized D-A-D type fused-ring aromatic imide interfacial material is separated by any one of precipitation and filtration, silica gel column chromatography, solution recrystallization, and spray drying.

5. A D-A-D type fused-ring aromatic imide interfacial material, characterized in that, It has the structure shown below:

6. Use of the D-A-D type fused-ring aromatic imide interfacial material according to claim 1 or 5 as a cathode interfacial material.

7. The application according to claim 6, characterized in that The D-A-D type fused-ring aromatic imide interfacial material is made into a cathode interfacial layer for an organic solar cell device.

8. The application according to claim 7, wherein The preparation process of the cathode interfacial layer is: dissolving the D-A-D type fused-ring aromatic imide interfacial material in an alcohol solvent and preparing the cathode interfacial layer by a solution processing method.

9. The application according to claim 8, characterized in that The solvent uses at least one of methanol, ethanol, isopropanol, and trifluoroethanol.

10. The application according to claim 8, characterized in that, The film thickness of the D-A-D type fused-ring aromatic imide interfacial material is 5 - 50 nm.

11. The application according to any one of claims 7 to 10, 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.

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