Phosphine-, nitrogen heterocyclic cation-containing ionene polymers, methods of making the same, cathode interfacial layer materials, and organic solar cells

Abstract

The present application relates to the technical field of organic solar cell, in particular to a violet polymer containing phosphine and nitrogen heterocyclic cation, a preparation method thereof, a cathode interface layer material and an organic solar cell.The structural formula of the violet polymer is shown as follows: wherein R is selected from a substituted or unsubstituted alkyl chain or a substituted or unsubstituted alkoxy chain; Ar is selected from a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl; N represents phosphine or nitrogen heterocycle; and X represents a counterion group.The violet polymer has good processability, strong interface modification capability and excellent thermal stability, can reduce the work function of an air stable metal electrode, weaken the interface barrier, thereby realizing barrier-free charge transport, inhibiting charge recombination, and effectively improving the photoelectric conversion efficiency of the organic solar cell.

Description

Technical Field

[0001] This invention relates to the field of organic solar cell technology, and more specifically, to violet polymers containing phosphine and nitrogen heterocyclic cations, their preparation methods, cathode interface layer materials, and organic solar cells. Background Technology

[0002] Organic solar cells (OSCs) have attracted widespread attention over the past few decades due to their advantage of using low-cost solution processing to fabricate large-area flexible devices. Currently, single-junction conventional OSC devices with photoelectric conversion efficiencies exceeding 19% have been successfully designed, demonstrating extremely bright commercial application prospects. In the design and development of OSCs, in addition to developing novel photoactive layers, effectively improving charge extraction and transport at the interface is also essential. For example, the cathode interlayer (CIL) located between the active layer and the metal cathode can effectively reduce the work function (WF) of the metal cathode and eliminate the energy barrier at the interface between the active layer and the cathode, promoting selective electron collection and transport. Amine-terminated polyfluorene derivatives (PFNs) and aliphatic amine polymers (PEI and PEIE) represent two classic CILs. However, their poor charge transport performance limits their operation to a thickness of only a few nanometers, posing stringent requirements for device fabrication processes. To achieve thick-film fabrication, naphthalenediimides (NDIs) and perylenediimides (PDIs), which possess high electron mobility, have been introduced into cell interlayers (CILs). However, small molecules based on NDI or PDI typically exhibit a strong tendency to aggregate and crystallize, which is detrimental to the fabrication of uniform and smooth interlayers. Integrating NDI or PDI into the conjugated polymer backbone with a donor-acceptor (DA) structure is an alternative strategy to promote intramolecular charge transfer (ICT). This also simultaneously narrows the band gap and expands the absorption spectrum of the interlayer, competing with the absorption of the photoactive layer in multilayer solar cells. Furthermore, the cumbersome synthesis steps of conjugated polymers significantly increase the cost of OSC devices, hindering their further development. Therefore, developing CILs with strong WF modification capabilities, weak or no absorption in the visible light region, and high conductivity for thick-film fabrication presents a significant challenge.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide phosphine- and nitrogen-containing heterocyclic cation-containing violetene polymers, their preparation methods, cathode interface layer materials, and organic solar cells. The phosphine- and nitrogen-containing heterocyclic cation-containing violetene polymers provided in this invention exhibit good processability, strong interface modification capabilities, and excellent thermal stability. They can reduce the work function of air-stabilized metal electrodes, weaken the interface barrier, thereby achieving unimpeded charge transport, suppressing charge recombination, and thus effectively improving the photoelectric conversion efficiency of organic solar cells.

[0005] This invention is implemented as follows:

[0006] In a first aspect, the present invention provides a violet polymer containing phosphine and nitrogen heterocyclic cations, the structural formula of which is shown below:

[0007] Wherein, R is selected from substituted or unsubstituted alkyl chains or substituted or unsubstituted alkoxy chains; Ar is selected from substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups; N represents a phosphine- or nitrogen-containing heterocycle; and X represents a counterionic group.

[0008] Secondly, the present invention provides a method for preparing the phosphine- and nitrogen-containing heterocyclic cation-based violet polymer described in the foregoing embodiments, comprising synthesizing the phosphine- and nitrogen-containing heterocyclic cation-based violet polymer according to the following synthetic route:

[0009]

[0010] Thirdly, the present invention provides a cathode interface layer material, which is prepared by the violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments.

[0011] Fourthly, the present invention provides an organic solar cell, which is prepared by the violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments or the cathode interface layer material as described in the foregoing embodiments.

[0012] Fifthly, embodiments of the present invention provide an organic semiconductor material prepared by a violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments.

[0013] Sixthly, embodiments of the present invention provide a lithium-ion battery prepared by a violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments.

[0014] The present invention offers the following advantages: In this embodiment, the introduction of phosphine or nitrogen heterocycles into the violet polymer imparts excellent thermal stability to the polymer, overcoming the Hoffmann elimination reaction and providing a possibility for the long-term stability of photovoltaic devices. Simultaneously, the nitrogen heterocycle structure effectively provides more regular interfacial dipoles, thereby effectively reducing the work function (Ag / Cu / Au) of the metal electrode and improving the photoelectric conversion efficiency of organic solar cells. Furthermore, the synthesis process is simple, efficient, and environmentally friendly. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figures 1-2 The result diagram of the JV characteristics provided in the embodiment of the present invention;

[0017] Figure 3 The image shows the results of the photo-aging test of the organic solar cell provided in the embodiment of the present invention;

[0018] Figure 4 The ultraviolet photoelectron spectrum provided in the embodiments of the present invention;

[0019] Figure 5 This is a graph showing the measurement results of a Kelvin probe provided in an embodiment of the present invention;

[0020] Figure 6 Grazing incidence X-ray diffraction pattern provided in an embodiment of the present invention;

[0021] Figure 7 An atomic force microscope image provided for an embodiment of the present invention;

[0022] Figure 8 The graph shows the test results of the charge recombination characteristics of the organic solar cell provided in the embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] This invention provides a violet polymer containing phosphine and nitrogen heterocyclic cations, the structural formula of which is shown below:

[0025] Wherein, R is selected from substituted or unsubstituted alkyl chains or substituted or unsubstituted alkoxy chains; Ar is selected from substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups; N represents a phosphine- or nitrogen-containing heterocycle; and X represents a counterionic group.

[0026] It should be noted that the counterion group refers to the anion relative to the N cation; any anion with the corresponding chemical valence can be used. For example, F can be chosen. - Cl - ,Br - I - OTf - HSO4 - OH - H2PO4 - BF4 - and Tf2N - Any one of the above, but not limited to the anions mentioned above.

[0027] Further, R is selected from substituted or unsubstituted C2-C20 alkyl chains or substituted or unsubstituted C2-C20 alkoxy chains. Specifically, unsubstituted C2-C20 straight alkyl chains can be selected, such as ethyl, propyl, hexyl, butyl, and pentyl, etc., or branched alkyl chains can be selected. At least one hydrogen on one carbon of the alkyl group, or at least two hydrogens on two carbons, or multiple hydrogens on multiple carbons, can be substituted by halogen, hydroxyl, nitro, or other groups. Alternatively, unsubstituted C2-C20 straight alkoxy chains can be selected, including but not limited to pentoxy and hexoxy, or branched alkoxy chains can be selected. At least one hydrogen on one carbon of the alkoxy group, or at least two hydrogens on two carbons, or multiple hydrogens on multiple carbons, can be substituted by halogen, hydroxyl, nitro, or other groups.

[0028] Furthermore, the substituted or unsubstituted aryl groups in Ar include substituted or unsubstituted monocyclic or polycyclic aromatic groups with 6-50 carbon atoms. Specifically, any one of substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthraceneyl, and substituted or unsubstituted pyreneyl; including but not limited to phenyl, benzyl, p-benzyl, m-benzyl, naphthyl, anthraceneyl, and pyreneyl. At least one hydrogen atom in naphthyl, anthraceneyl, and pyreneyl may also be substituted by halogen, hydroxyl, alkyl, alkoxy, nitro, and sulfoxide groups.

[0029] Furthermore, the substituted or unsubstituted heteroaryl group in Ar includes substituted or unsubstituted monocyclic or polycyclic heteroaryl groups with 6-50 carbon atoms and 1-4 heteroatoms; wherein the heteroatoms are selected from any one of N, S, F, Si, and Se.

[0030] Furthermore, Ar is selected from any one of the groups shown in the following structural formulas:

[0031]

[0032]

[0033] Further, N is selected from substituted or unsubstituted monocyclic or polycyclic groups having 5-20 carbon atoms and 1-5 nitrogen atoms; specifically, N is selected from any one of substituted or unsubstituted imidazoles, substituted or unsubstituted pyridines, substituted or unsubstituted pyrimidines, and substituted or unsubstituted pyrazines; for example, N is selected from any one of the groups shown in the following structural formulas:

[0034]

[0035] Furthermore, the violet polymer containing phosphine and nitrogen heterocyclic cations is selected from any one of the compounds shown in the following structural formulas:

[0036]

[0037] Ionene polymers are a unique class of polyelectrolytes in which ionic substances reside within the polymer backbone rather than as side groups. This characteristic allows ionic alkenes with high ionic densities to generate large interfacial dipoles, reducing the metal electrode flux density (WF). Therefore, embodiments of this invention propose the concept of electroactive ions by integrating conjugated building blocks into conventional ionenes to address the limitations of non-conjugated polymer backbones as OSC interlayers in this material platform. This compound combines the excellent electrical properties of conjugated small molecules with the superior solution processability of polymers, potentially enabling CILs with better thickness tolerance during device operation. Conventionally developed electroactive ionenes are limited to N,N-dimethyl-substituted ammonium cations linked by two rotatable single-chain hydrocarbons; these cations can be degraded by Hoffmann elimination, thereby disrupting charge distribution and morphology. Embodiments of this invention, however, design and synthesize a series of novel electroactive ionic alkenes by combining nitrogen-containing heterocycles with various π-coupled diimides via the Menshutkin reaction. Aromatic diimides are used as π-conjugated subunits due to their excellent photostability and thermal stability, high charge carrier mobility, and low LUMO energy level. The structure of the π-conjugated core can provide a platform for better control over the photoelectric properties and morphology of electroactive violets. Results show that these polymers possess good processability and strong interfacial modification capabilities, enabling them to reduce the work function (WFs) of air-stabilized metal electrodes (Ag, Cu, and Au), weaken interfacial barriers, thereby achieving unimpeded charge transport and suppressing charge recombination.

[0038] Secondly, the present invention provides a method for preparing the phosphine- and nitrogen-containing heterocyclic cation-based violet polymer described in the foregoing embodiments, comprising synthesizing the phosphine- and nitrogen-containing heterocyclic cation-based violet polymer according to the following synthetic route:

[0039]

[0040] Specifically, the conditions for forming compound 3 include: a molar ratio of compound 1 to compound 2 of 1:3-6, specifically 1 mmol:4-5 mmol, preferably 1 mmol:4 mmol. The solvent can be an alcohol solvent, such as ethanol, or an amide solvent, such as N,N-dimethylformamide, preferably N,,N-dimethylformamide, wherein the amount of solvent, such as ethanol, used is 10 mL-30 mL, preferably 20 mL. The reaction is preferably carried out under heating conditions, with a heating temperature of 80°C-150°C, specifically 90°C-130°C, preferably 120°C. The reaction time is 10-40 hours, specifically 24-36 hours, preferably 24 hours.

[0041] The preparation of compound (5) is preferably carried out in N,N dimethylformyl at a temperature of 80℃-130℃. The amounts of compound (3) and compound (4) are strictly in the ratio of 1 mmol:1 mmol, and the amount is preferably 10 mL.

[0042] The preferred reaction steps are as follows: Compounds (3) and (4) are completely dissolved in N,N-dimethylformyl solution, and then the oxygen in the reaction system is removed by freezing. Subsequently, the system is heated at 120°C for 48 hours to obtain compound (6). After the reaction is completed, compound (6) is preferably purified as follows: The reaction solution is precipitated in dichloromethane, filtered to obtain solid violet polymer (6), the product is washed multiple times with dichloromethane solution, and then placed in a vacuum oven for 12 hours to obtain a clean product.

[0043] It should be noted that the amounts of each reactant used in the preparation process described above in the embodiments of the present invention are all calculated based on a certain reactant. In actual operation, it is permissible to make corresponding changes to the amounts of all reactants and solvents.

[0044] Thirdly, the present invention provides a cathode interface layer material, which is prepared by the violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments.

[0045] Fourthly, the present invention provides an organic solar cell, which is prepared by the violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments or the cathode interface layer material as described in the foregoing embodiments.

[0046] Fifthly, embodiments of the present invention provide an organic semiconductor material prepared by a violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments. This organic semiconductor material exhibits good biocompatibility with organisms in multifunctional biological systems. Utilizing the excellent light-harvesting capabilities of semiconductors and their synthetic capabilities with biological cells or enzymes, it represents a promising chemical synthesis platform. Due to the excellent photoelectric conversion capabilities of such materials in electrochemical devices, as well as their finely defined leading molecular orbital energy levels and optical band gaps, organic semiconductor materials offer an excellent opportunity to develop highly efficient solar-chemical-biohybrid systems.

[0047] Sixthly, embodiments of the present invention provide a solid electrolyte for a lithium-ion battery, which is prepared by a violet polymer containing phosphine and nitrogen heterocyclic cations as described in any of the foregoing embodiments.

[0048] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0049] Example 1

[0050] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as PMD-DABC), comprising:

[0051] Perform the synthesis according to the following synthesis path:

[0052] Specifically as follows:

[0053] (1) Synthesis of PMD-Br: Pyromellitic dianhydride (1.1 g, 5.0 mmol), 3-bromopropylamine hydrobromide (3.3 g, 15.0 mmol), triethylamine (3.0 mL), and acetic acid (30 mL) were placed in a 100 mL round-bottom flask. After the solid was completely dissolved, the solution was heated under reflux for 18 hours. After cooling to room temperature, the white precipitate was filtered off and washed successively with deionized water and EtOH. The crude product was further purified by silica gel chromatography to obtain pure PMD-Br (1.42 g, yield = 62.0%). 1 HNMR (400MHz, CDCl3, δ): 8.30 (s, 2H), 3.92 (t, J = 6.8 Hz, 4H), 3.43 (t, J = 6.5 Hz, 4H), 2.30 (m, 4H).

[0054] (2) Synthesis of PMD-DABC: PMD-Br (229.1 mg, 0.5 mmol), 1,4-diazabicyclo[2.2.2]octane (56.1 mg, 0.5 mmol), and N,N-dimethylformamide (2 mL) were added to a well-dried glass pressure vessel. The reaction mixture was heated to 130 °C for 72 hours under nitrogen protection. After cooling to room temperature, the reaction mixture was poured into chloroform. The precipitate was collected and dried under vacuum to give PMD-DABC as a pale yellow solid in a yield of 86.0% (245 mg). 1 HNMR (400MHz, D2O, δ): 8.26 (m, 2H), 3.97 (m, 12H), 3.82 (m, 4H), 3.70 (m, 4H), 2.23 (m, 4H). GPC (TFE): Mw=21.2kDa, Mn=18.8kDa,

[0055] Example 2

[0056] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as NDI-DABC), comprising:

[0057] Perform the synthesis according to the following synthesis path:

[0058] Specifically as follows:

[0059] (1) Synthesis of NDI-6OH: 1,4,5,8-naphthalenetetracarboxylic dianhydride (1.34 g, 5.0 mmol), 6-amino-1-hexanol (2.35 g, 20.0 mmol), and DMF (30 mL) were added to a 100 mL round-bottom flask. The solution was heated to 120 °C for 36 hours under a nitrogen atmosphere. After complete conversion of the starting materials, the reaction mixture was cooled to room temperature and poured into water. The purple-pink crystals were filtered and washed three times with water and methanol. After vacuum drying, NDI-6OH in the form of purple crystals was obtained (1.84 g, yield = 79.0%). 1 HNMR (400MHz, CDCl3, δ): 8.79 (s, 4H), 4.23 (t, J = 7.5Hz, 4H), 3.68 (t, J = 6.4Hz, 4H), 1.80 (m, 4H), 1.63 (m, 4H), 1.49 (m, 8H).

[0060] (2) Synthesis of NDI-Br: NDI-6OH (1.40 g, 3.0 mmol) and DMF (30 mL) were added to a 100 mL round-bottom flask, and the mixture was heated at 90 °C until the solid was completely dissolved. The reaction system was then cooled to 0 °C, and PBr3 (4.23 mL, 15.0 mmol) was added dropwise. The mixture was stirred at 0 °C for 0.5 h, and then heated at 110 °C for 48 h. The reaction mixture was then cooled to room temperature, and deionized water (200 mL) was added to quench the reaction. The precipitate was collected by filtration, washed several times sequentially with water and methanol, and finally dried under reduced pressure at 50 °C for 24 h to obtain a yellow solid NDI-Br (1.08 g, yield = 61.0%). 1 HNMR (400MHz, CDCl3, δ): 8.78 (s, 4H), 4.23 (t, J = 7.5Hz, 4H), 3.44 (t, J = 6.8Hz, 4H), 1.91 (m, 4H), 1.78 (m, 4H), 1.52 (m, 8H).

[0061] (3) Synthesis of NDI-DABC: NDI-DABC was synthesized using the same method as PMD-DABC (yellow solid, yield = 89.0%). 1 HNMR (400MHz, CF3COOD, δ): 9.01 (m, 4H), 4.44 (m, 4H), 4.32 (m, 12H), 3.79 (m, 4H), 2.07-1.99 (m, 8H), 1.69 (m, 8H). GPC (TFE): Mw=68.0kDa, Mn=45.2kDa.

[0062] Example 3

[0063] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as PDI-DABC), comprising:

[0064] Perform the synthesis according to the following synthesis path:

[0065] Specifically as follows:

[0066] (1) Synthesis of PDI-6OH: PDI-6OH was synthesized using the same method as NDI-6OH (black solid, yield = 71.0%). 1 HNMR (400MHz, CF3COOD, δ): 8.99 (m, 8H), 4.69 (t, J = 6.5 Hz, 4H), 4.55 (t, J = 7.8 Hz, 4H), 2.08 (m, 8H), 1.79 (m, 8H).

[0067] (2) Synthesis of PDI-Br: PDI-Br was synthesized using the same method as NDI-Br (deep red solid, yield = 73.0%). 1 HNMR (400MHz, CDCl3 / CF3COOH, δ): 8.79 (m, 8H), 4.27 (t, J = 7.4Hz, 4H), 3.45 (t, J = 6.7Hz, 4H), 1.93 (m, 4H), 1.82 (m, 4H), 1.54 (m, 8H).

[0068] (3) Synthesis of PDI-DABC: PDI-DABC was synthesized using the same method as PMD-DABC. The dark solid was washed several times with chloroform and extracted with methanol. Impurities and low molecular weight products were removed by dialysis with methanol (MWCO 3.5 kDa) for 72 h (yield = 65.0%). 1 HNMR (400MHz, CF3COOD, δ): 8.88 (m, 8H), 4.50 (m, 4H), 4.30 (m, 12H), 3.81 (m, 4H), 2.15-2.06 (m, 8H), 1.76 (m, 8H). GPC (TFE): Mw=26.0kDa, Mn=23.0kDa.

[0069] Example 4

[0070] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as PMD-MI), comprising:

[0071] Perform the synthesis according to the following synthesis path:

[0072] Specifically as follows:

[0073] (1) Synthesis of PMD-M: Pyromellitic dianhydride (1.1 g, 5.0 mmol), 1-(3-aminopropyl)imidazole (1.8 g, 14.4 mmol), and DMF (10 mL) were added sequentially to a 100 mL round-bottom flask. The reaction mixture was heated at 120 °C for 18 hours. After that, the reaction was allowed to cool to room temperature. The reaction mixture was then poured into deionized water (50 mL) and the solution was placed in a refrigerator (4 °C). The solid was filtered, washed with water, and further dried under vacuum overnight to give a pure product as a grayish-white solid in a yield of 68.5% (1.48 g). 1 HNMR (400MHz, DMSO-d6): δ (ppm): 8.19 (s, 2H), 7.63 (s, 2H), 7.20 (s, 2H), 6.87 (s, 2H), 4.05 (t, 4H), 3.62 (t, 4H), 2.09 (m, 4H).

[0074] (2) Synthesis of PMD-MI: PMD-M (216.0 mg, 0.5 mmol) and 1,3-dibromopropane (100.9 mg, 0.5 mmol) were dissolved in 2 mL of LDMF in a well-dried glass pressure vessel. The reaction mixture was heated to 130 °C for 48 hours under nitrogen protection. After cooling to room temperature, the reaction mixture was poured into dichloromethane. The precipitate was collected and dried under vacuum to give PMD-DI as a plastic-like yellow solid in 85.4% (270 mg). 1 HNMR (400MHz, DMSO-d6): δ (ppm): 9.33 (m, 2H), 8.24 (m, 2H), 7.86 (m, 4H), 4.30 (m, 8H), 3.70 (m, 4H), 2.44 (m, 2H), 2.23 (m, 4H). GPC (TFE): Mw = 15.1kDa, Mn = 14.9kDa. PDI: 1.01.

[0075] Example 5

[0076] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as NDI-MI), comprising:

[0077] Perform the synthesis according to the following synthesis path:

[0078] Specifically as follows:

[0079] (1) Synthesis of NDI-M: NDI-M was synthesized using the same method as PMD-M (brown crystals, yield = 70.0%). 1 HNMR (400MHz, DMSO-d6): δ (ppm): 8.66 (s, 4H), 7.67 (s, 2H), 7.22 (s, 2H), 6.88 (s, 2H), 4.09 (m, 8H), 2.14 (m, 4H).

[0080] (2) Synthesis of NDI-MI: NDI-M (241.09 mg, 0.5 mmol) and 1,3-dibromopropane (100.09 mg, 0.5 mmol) were dissolved in 2 ml of a mixture of chloroform and methanol in equal volume ratio. The solution was then added to a 10 ml Schlenk tube and polymerized at 70 °C under a nitrogen atmosphere for 48 hours. The reaction solution was then added to dichloromethane to precipitate a brownish-yellow polymer (yield = 86.8%). 1HNMR (400MHz, DMSO-d6 / CF3COOD): δ (ppm): 9.36 (s, 2H), 8.64 (m, 4H) 7.88 (m, 4H), 4.41-4 .24(m,8H),4.11(m,4H),2.67(m,4H),2.24(m,4H).GPC(TFE): Mw=18.0kDa, Mn=12.5kDa.

[0081] Example 6

[0082] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as PDI-MI), comprising:

[0083] Perform the synthesis according to the following synthesis path:

[0084] Specifically as follows:

[0085] (1) Synthesis of PDI-M: PDI-M was synthesized using the same method as PMD-M (dark red crystals, yield = 92.0%). 1 HNMR (400MHz, DMSO-d6 / CF3COOD): δ (ppm): 9.18 (s, 2H), 8.45 (d, 4H) 8.22 (d, 4H), 7.86 (s, 2H), 7.73 (s, 2H), 4.36 (t, 4H), 4.11 (m, 4H), 2.27 (m, 4H).

[0086] (2) Synthesis of PDI-MI: PDI-M (151.7 mg, 0.25 mmol) and 1,3-dibromopropane (50.5 mg, 0.25 mmol) were dissolved in 1.2 ml of trifluoroethanol solvent. The solution was then added to a 10 ml Schlenk tube and polymerized at 90 °C under a nitrogen atmosphere for 48 hours. The reaction solution was then added to dichloromethane to precipitate a blackish-red polymer (yield = 87.2%). 1 HNMR (400MHz, D2O): δ (ppm): 9.07 (s, 2H), 8.11-7.92 (m, 8H) 7.66 (m, 4H), 4.45 (m, 4H), 4.33 (m, 4H), 3.99-3.75 (m, 8H), 2.69 (m, 4H), 2.21 (m, 4H). GPC (TFE): Mw=190.4kDa, Mn=37.6kDa.

[0087] Examples 7-9

[0088] Examples 7-9 provide methods for preparing nitrogen-containing heterocyclic violet polymers, specifically following the synthetic pathways described below:

[0089] The preparation methods of the nitrogen-containing heterocyclic violet polymers in Examples 7-9 are consistent with those in Examples 4-6 (PMD-MI, NDI-MI, and PDI-MI), and will not be described in detail here. The characterization of the products is provided as follows:

[0090] Example 7: PMD-PD: 1 HNMR(400MHz,CF3COOD,δ):8.84(m,4H),8.31(m,2H),7.60(m,4H),4.42(t,4H),4.15(m,4H),2.33(m,4H).

[0091] Example 8: NDI-PD: 1H NMR (400MHz, CF3COOD, δ): 9.01(m, 4H), 8.82(m, 4H), 7.28(m, 4H), 4.39(t, 4H), 4.05(m, 4H), 2.47(m, 4H).

[0092] Example 9: PDI-PD: 1H NMR (400MHz, CF3COOD, δ): 9.13 (m, 8H), 8.93 (m, 4H), 7.89 (m, 4H), 4.51 (t, 4H), 4.23 (m, 4H), 2.82 (m, 4H).

[0093]

[0094] Example 10

[0095] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as PMD-PM), comprising:

[0096] Perform the synthesis according to the following synthesis path:

[0097] Specifically,

[0098] (1) Synthesis of PMD-OH: Pyromellitic dianhydride (1.1 g, 5.0 mmol), 3-amino-1-propanol (1.5 g, 20.0 mmol), and DMF (30 mL) were added to a 100 mL round-bottom flask. The solution was heated to 120 °C for 36 hours under a nitrogen atmosphere. After the starting material was completely converted, the reaction mixture was cooled to room temperature and poured into water. The mixture was filtered white and washed three times with water and methanol. After vacuum drying, PMD-OH was obtained (1.43 g, yield = 89.5%). 1 HNMR (400MHz, CDCl3, δ): 8.30 (m, 2H), 4.01 (t, 4H), 3.60 (t, 4H), 2.03 (m, 4H).

[0099] (2) Synthesis of PMD-Py: PMD-OH (1.00 g, 3.0 mmol), 4-hydroxypyrimidine (1.15 g, 12.0 mmol), triphenylphosphine (5.25 g, 20.0 mmol), and DMF (40 mL) were added to a 100 mL round-bottom flask. After the mixture was completely dissolved, nitrogen gas was purged to completely remove oxygen from the system. The reaction system was then cooled to 0 °C, and a DMF solution of diethyl azodicarbonate (3.48 mL, 15.0 mmol) was added dropwise. The mixture was reacted at room temperature for 24 hours. Deionized water was then added, and the precipitate was collected by filtration. After washing several times with water, the product was purified by column chromatography to obtain a white solid PMD-Py (0.50 g, yield = 34.2%). 1 HNMR (400MHz, CDCl3, δ): 8.75 (s, 2H), 8.39 (d, 2H), 8.28 (s, 2H), 6.70 (d, 2H), 4.53 (t, 4H), 4.40 (t, 4H), 2.30 (m, 4H).

[0100] (3) Synthesis of PMD-PM: PMD-Py (244.23 mg, 0.5 mmol), 1,3-dibromopropane (100.9 mg, 0.5 mmol), and N,N-dimethylformamide (2 mL) were added to a well-dried glass pressure vessel. The reaction mixture was heated to 130 °C for 72 hours under nitrogen protection. After cooling to room temperature, the reaction mixture was poured into chloroform. The precipitate was collected and dried under vacuum to give PMD-PM as a pale yellow solid, with a yield of 79.0% (284.4 mg). 1 HNMR (400MHz, CF3COOD, δ): 8.50 (m, 4H), 8.30 (m, 2H), 7.00 (m, 2H), 4.13 (m, 8H), 4.06 (m, 4H), 2.18 (m, 6H).

[0101] Example 11

[0102] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as NDI-PM), comprising:

[0103] Perform the synthesis according to the following synthesis path:

[0104] Specifically,

[0105] (1) Synthesis of NDI-OH: NDI-OH was synthesized using the same method as PMD-OH (yellow crystals, yield = 83.0%). 1HNMR (400MHz, CDCl3, δ): 8.82 (m, 4H), 4.41 (t, 4H), 3.67 (t, 4H), 2.05 (m, 4H).

[0106] (2) Synthesis of NDI-Py: NDI-Py was synthesized using the same method as PMD-Py (white solid, yield = 30.4%). 1 HNMR (400MHz, CDCl3, δ): 8.78 (s, 4H), 8.77 (s, 2H), 8.42 (d, 2H), 6.72 (d, 2H), 4.57 (t, 8H), 4.44 (t, 4H), 2.31 (m, 6H).

[0107] (3) Synthesis of NDI-PM: NDI-PM was synthesized using the same method as PMD-PM (yellow solid, yield = 77.0%). 1 HNMR(400MHz,CF3COOD,δ):8.79(m,4H),8.31(m,4H),7.01(m,2H),4.20(m,8H),4.11(m,4H),2.25(m,6H).

[0108] Example 12

[0109] This invention provides a method for preparing a nitrogen-containing heterocyclic violet polymer (denoted as PDI-PM), comprising:

[0110] Perform the synthesis according to the following synthesis path:

[0111] Specifically,

[0112] (1) Synthesis of PDI-OH: PDI-OH was synthesized using the same method as PMD-OH (black solid, yield = 65.0%). 1 HNMR (400MHz, CF3COOD, δ): 8.98 (m, 8H), 4.71 (m, 4H), 4.18 (m, 4H), 2.40 (m, 4H).

[0113] (2) Synthesis of PDI-Py: PDI-Py was synthesized using the same method as PMD-Py (red solid, yield = 31.4%). 1 HNMR(400MHz,CF3COOD,δ):9.31(m,2H),9.08(m,8H),8.31(m,2H),7.20(m,2H),4.79(m,4H),4.70(t,4H),2.70(m,4H).

[0114] (3) Synthesis of PDI-PM: PDI-PM was synthesized using the same method as PMD-PM. (Blackish-red solid, yield = 62.5%) 1 HNMR(400MHz,CF3COOD,δ):8.97(m,4H),8.77(m,8H),7.01(m,2H),4.44(m,8H),4.35(m,4H),2.50(m,6H).

[0115] Examples 13-15

[0116] Examples 13-15 provide methods for preparing nitrogen-containing heterocyclic violet polymers, specifically following the synthetic pathways described below:

[0117]

[0118] The preparation methods of the nitrogen-containing heterocyclic violet polymers in Examples 13-15 are consistent with those in Examples 10-12 (PMD-PM, NDI-PM, and PDI-PM), and will not be described in detail here. The characterization of the products is provided as follows:

[0119] Example 13: PMD-PZ: 1 HNMR(400MHz,CF3COOD,δ):9..10(m,6H),8.28(m,2H),4.13(m,8H),4.06(m,4H),2.18(m,6H).

[0120] Example 14: NDI-PZ: 1 HNMR(400MHz,CF3COOD,δ):9.15(m,6H),8..33(m,4H),7.01(m,2H),4.35(m,8H),4.18(m,4H),2.27(m,6H).

[0121] Example 15: PDI-PZ: 1 HNMR(400MHz,CF3COOD,δ):9..18(m,6H),8.86(m,8H),7.62(m,2H),4.48(m,8H),4.29(m,4H),2.49(m,6H).

[0122] Examples 16-18

[0123] Examples 13-15 provide methods for preparing phosphine-based cationic violet polymers, specifically following the synthetic pathways described below:

[0124]

[0125] The preparation methods of the phospho-based violet polymers in Examples 16-18 are consistent with the preparation methods of the nitrogen-containing heterocyclic violet polymers in Examples 1-3 (PMD-DABC, NDI-DABC, and PDI-DABC), and will not be described in detail here. The characterization of the products is provided as follows:

[0126] Example 16: PMD-PI: 1 HNMR(400MHz,CF3COOD,δ):8.39(m,2H),7.54-7.91(m,20H),4.35(m,4H),3.66(m,4H),3.28(m,4H),1.19-1.95(m,20H)

[0127] Example 17: NDI-PI: 1 HNMR(400MHz,CF3COOD,δ):8.73(m,4H),7.61-7.99(m,20H),4.26(m,4H),3.65(m,4H),3.28(m,4H),1.34-1.98(m,20H).

[0128] Example 18: PDI-PI: 1 HNMR (400MHz, CF3COOD, δ): 8.69 (m, 8H), 7..63 (m, 12H), 7.26 (m, 8H), 4.26 (m, 4H), 2.86 (m, 4H), 2.44 (m, 4H), 1.13-1.97 (m, 20H).

[0129] Examples 19-23

[0130] This embodiment provides a method for fabricating an organic solar cell, including:

[0131] OSC is manufactured using a conventional structure of indium tin oxide (ITO) / poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) / active layer / cathode interlayer / metal electrode. First, the ITO-coated glass substrate is continuously cleaned in an ultrasonic bath of detergent, deionized water, acetone, and isopropanol, and then treated in a UV ozone generator for 15 minutes. PEDOT: PSS aqueous solution is spin-coated onto the ITO surface at 3500 rpm (~40 nm) and then annealed at 150°C for 15 minutes under ambient atmosphere. The substrate is then immediately transferred to a glove box (nitrogen atmosphere, O2 < 1 ppm, H2O < 1 ppm). PM6:Y6 (1:1.2, w:w) is dissolved in chloroform with 0.5% by volume of 1-chloronaphthalene. An active layer is formed by spin-coating the solution on top of PEDOT:PSS at 1500 rpm for 40 seconds, followed by thermal annealing at 80°C for 10 minutes. For PM6:L8-BO-based cells, the PM6:L8-BO (1:1.2, w:w) mixture was completely dissolved in chloroform to a total concentration of 15.4 mg / mL. -1 Diiodomethane (DIM) was used as a solvent additive at a volume ratio of 0.5%. The active layer was formed by spin-coating the solution onto PEDOT:PSS at 3000 rpm, followed by thermal annealing at 90°C for 5 minutes. Then, trifluoroethanol (TFE) solutions containing different concentrations (0.5-12 mg / mL) of the nitrogen-containing heterocyclic violet polymer prepared in Example 1 were spin-coated onto the active layer at 4000 rpm to generate cathode interlayers of varying thicknesses. Finally, at a 1×10⁻⁶… -6 An Ag cathode (100 nm) was deposited via thermal evaporation under a vacuum of mbar, with an effective device area of ​​0.04 cm². 2 .

[0132] Examples 24-34

[0133] Organic solar cells were prepared according to the preparation method provided in Example 16 above, except that the nitrogen-containing heterocyclic violet polymers of Examples 2-3 were used respectively.

[0134] Performance testing

[0135] (1) Determination of work function and photoelectric conversion efficiency

[0136] The photovoltaic parameters of the organic solar cells were measured, see Tables 1, 2 and 3.

[0137] Table 1 shows the results at AM 1.5G, 100mW cm⁻¹ -2 Photovoltaic parameters of PM6:Y6-based OSCs with different types of nitrogen-containing heterocyclic violetenes as cathode interlayers under illumination.

[0138]

[0139]

[0140] a a) Average of standard deviations obtained from at least 10 devices; the error represents ±1 standard deviation of the average obtained from at least ten devices; b) Short-circuit current (JSC) calculated from external quantum efficiency (EQE) spectra.

[0141] Table 2 shows the results at AM 1.5G, 100mW cm⁻¹. -2 Photovoltaic parameters of PM6:Y6-based OSCs with different types of nitrogen-containing heterocyclic violet as the cathode intermediate film under different film thicknesses.

[0142]

[0143]

[0144] a The average standard deviation obtained from at least 10 devices; the error is expressed as ±1 standard deviation of the average obtained from at least ten devices; b The short-circuit current (J) calculated based on the external quantum efficiency (EQE) spectrum. SC ).

[0145] Table 3 shows the results at AM 1.5G, 100mW cm⁻¹. –2 Detailed photovoltaic parameters of devices based on PM6:L8-BO and nitrogen-containing heterocyclic violet-based CIL under illumination.

[0146]

[0147] a The average standard deviation obtained from at least 10 devices; the error is expressed as ±1 standard deviation of the average obtained from at least ten devices; b The short-circuit current (J) calculated based on the external quantum efficiency (EQE) spectrum. SC ).

[0148] JV characteristics were tested using a 300W Xe lamp solar simulator (SS-F5-3A, ENLITECH) under simulated AM 1.5G illumination in an N2-filled glove box with a Keithley 2400 source meter, with intensity corrected for certified standard silicon solar cells. External quantum efficiency (EQE) spectra were obtained using a solar cell QE meter (QE-R3011, ENLITECH) calibrated with a xenon lamp probe.

[0149] See results Figure 1 and Figure 2 , Figure 1In the middle, A represents the JV curve of an organic solar cell based on a PMD-DABC violetene cathode interface layer with different film thicknesses; Figure 1 B represents the JV curve of organic solar cells based on NDI-DABC violetene cathode interface layers with different film thicknesses; Figure 1 C represents the JV curve of organic solar cells based on PDI-DABC violetene cathode interface layers with different film thicknesses; Figure 2 In the middle, A represents the JV curve of an organic solar cell with three violet cathode interface layers; Figure 2 JV curve of organic solar cell based on NDI-DABC cathode interface layer with a thickness of 105 nm.

[0150] The photo-aging test of organic solar cells was conducted at the maximum power point (MPP) using a white LED under continuous illumination to measure the photostability of the OSC (spectral region: 410-850 nm, simulated intensity: 100 mW cm⁻¹). -2 Suzhou D&R Instruments, PVLT-6001M-32A, device area: 0.04 cm² 2 Specifically, these devices were sealed with glass slides in an N2-filled glove box with UV bending adhesive (Norland Optical Adhesive 73). The encapsulated devices were irradiated with a 365nm UV lamp (output power: 5W) for 10 minutes, then intermittently moved outdoors and tested using a white light-emitting diode (LED) array with an intensity equivalent to 1-Sun as the light source. During the measurements, the devices were maintained at their maximum power point (MPP) at a temperature of approximately 25°C.

[0151] See results Figure 3 , Figure 3 This indicates the duration of a single solar irradiation (100 mW cm⁻¹). -2 Under the condition of 3, the normalized efficiency (average results from three independent devices) of PM6:Y6 devices based on three violet cathode interface layers is compared with the aging time.

[0152] Based on the above results, taking the DABC series of nitrogen-containing heterocyclic violetenes (nitrogenous heterocyclic violetene polymers prepared in Examples 1-3) as an example, they serve as the cathode interlayer in organic solar cells (OSCs). Regardless of the size of the aromatic diimine, these nitrogen-containing heterocyclic violetene polymers can generate strong interfacial dipoles to effectively reduce the work function (WF) of air-stabilized metal electrodes (including Ag, Cu, and Au). The photoelectric and morphological properties of these ionic polymers can be further tuned by substituting the aromatic diimine, thereby achieving high conductivity and good compatibility with the active layer. Using PMD-DABC, NDI-DABC, and PDI-DABC as PM6:Y6 / PM6:L8-BO binary devices in CIL, photoelectric conversion efficiencies (PCE) of 17.06% / 17.89%, 17.44% / 18.43%, and 17.23% / 18.32% were obtained, respectively. Impressively, even with the NDI-DABC interlayer thickness increasing to 105 nm, PCE of 14.84% and 16.04% were still achieved in PM6:Y6 and PM6:L8-BO-based devices, respectively. This is the best result for OSCs with CIL thicknesses >100 nm, demonstrating the superiority of NDI-DABC in large-area device fabrication. Furthermore, devices based on NDI-DABC and PDI-DABC showed improved performance under continuous solar irradiation (T0). 80 In the maximum power point (MPP) tracking test of the active layer (PM6:Y6) for more than 1000 hours, it maintained more than 80% of its initial efficiency, which is one of the most stable results reported for binary positive organic photovoltaic devices.

[0153] (2) Ultraviolet photoelectron spectroscopy and Kelvin probe (SKP) measurement

[0154] Ultraviolet photoelectron spectroscopy (UPS) was used to investigate the electronic structure of the nitrogen-containing heterocyclic violet polymers (DABC series) from Examples 1-3 on metal electrodes. Specifically, UPS measurements were performed on a Kratos supra. The samples were spin-coated onto a silver substrate to a thickness of ~5 nm, and the test unit consisted of a helium discharge lamp (He I line, 21.2 eV) as the ultraviolet excitation source and a hemispherical sector energy analyzer. All samples measured by UPS were biased at -9 V to compensate for the instrument work function difference caused by the repulsion of low-energy electrons.

[0155] Kelvin probe (SKP) measurements were performed using a KP technology model SKP5050 in ambient air. The test samples consisted of heterocyclic violetene spin-coated onto silver, copper, and gold, respectively.

[0156] See results Figure 4 and Figure 5 . Figure 4 Ultraviolet photoelectron spectroscopy (UPS) spectra of PMD-DABC, NDI-DABC, PDI-DABC, and silver substrates; Figure 5 The scanned Kelvin probe maps (SKPs) are obtained by coating three types of violetene, PMD-DABC, NDI-DABC and PDI-DABC, onto (A) a silver substrate, (B) a copper substrate and (C) a gold substrate.

[0157] Based on the above results, it can be concluded that in a UPS, the secondary electron cutoff (E) in the high-coupling (low-energy) region... SEC The effect of the contact material on the electrode work function (WF) is determined by the difference between the original metal electrode and the ion-polymer coated electrode. SEC The offset can be used to quantify the interfacial dipole value. Notably, when a thin layer of violetene is formed on an Ag substrate, all these electroactive violetenes induce an interfacial dipole of approximately –0.72 eV, corresponding to a WF reduction from ~4.59 eV (original Ag) to ~3.87 eV. This result was further confirmed by scanning Kelvin probe (SKP) measurements. For example, coating a thin layer of three nitrogen-modified heterocyclic violetene polymers on an Ag substrate can uniformly reduce the WF of Ag by 0.61–0.71 eV over a millimeter-square area. SKP measurements were also used to investigate the effect of the modified nitrogen-modified heterocyclic violetene polymers on the WF values ​​of two other commonly used air-stabilized metal electrodes, Ag and Cu. These DABC-based nitrogen-based heterocyclic violets exhibit similar WF-reducing capabilities. After modification with nitrogen-based heterocyclic violet polymers, the WF values ​​of gold and copper decreased significantly from 5.03 eV and 4.98 eV for PMD-DABC to 4.20 eV and 4.17 eV, NDI-DABC to 4.25 eV and 4.19 eV, and PDI-DABC to 4.28 eV and 4.19 eV. The above characterization fully confirms that nitrogen-based heterocyclic ionic groups can effectively reduce the WF of metal electrodes. This WF reduction in the cathode is beneficial for increasing the built-in potential (V) of solar cell devices. bi This is crucial for facilitating electron extraction to maximize V. OC J SC And FF.

[0158] (3) Thin film morphology study

[0159] The structural order of the nitrogen-containing heterocyclic violetene polymer films in Examples 1-3 was compared using grazing incidence X-ray diffraction (GIXD). Specifically, after the violetene material was coated onto a clean, flat silicon wafer, an X-ray beam struck the sample at a grazing angle higher than and lower than the critical angle of the polymer film (αc = 0.16) but lower than the critical angle of the silicon substrate (αc = 0.22). The wavelength of the X-rays was [wavelength value missing]. The scattering intensity was detected using a PILATUS 1M detector.

[0160] The effect of nitrogen-containing heterocyclic violetene on the surface texture of the photoactive layer (PM6:Y6) was investigated using atomic force microscopy (AFM), specifically on a Bruker ICON03040155 microscope. Film thickness was determined using a Bruker surface profilometer (model DEKTAK-XT) and AFM. Samples were obtained by spin-coating different concentrations of violetene solution onto the active layer material (PM6:Y6) film.

[0161] See section 6 for the results. Figure 7 . Figure 6 The images show the grazing incidence X-ray diffraction (GIXD) spectra of (A) PMD-DABC, (B) NDI-DABC, and (C) PDI-DABC violetenes; and the corresponding profiles in the out-of-plane and (E) in-plane directions. Figure 7 Atomic force microscopy (AFM) images of violetenes of different thicknesses, including PMD-DABC, NDI-DABC, and PDI-DABC.

[0162] Based on the above results, the hump-shaped diffraction pattern of PMD-DABC indicates its amorphous nature, while NDI-DABC exhibits moderate crystallinity and a better frontal orientation, showing good in-plane (IP) orientation. There is a clear layered stacking diffraction at that location, At this time, fuzzy π-π packing diffraction is observed in the out-of-plane (OOP) direction. This packing behavior facilitates charge transport through the interlayer in the solar cell. For PDI-DABC, a dominant edge packing mode with excessive crystallinity can be detected, which can be observed through multiple diffraction points and in the IP direction. The sharp diffraction peaks at the point of origin confirm this. Secondly, the effect of electroactive violetene on the surface texture of the photoactive layer (PM6:Y6) was investigated using atomic force microscopy (AFM). A thin (19 nm) electroactive violetene CIL coating helped reduce the root mean square roughness (Rq) from 1.61 nm to less than 1 nm. The smooth, uniform surface facilitated a favorable contact between the CIL and the metal electrode. With increasing film thickness, the surface morphology and Rq of the PMD-DABC and NDI-DABC samples remained good, consistent with their weak crystalline characteristics. In contrast, as the thickness of PDI-DABC increased to 105 nm, Rq increased to 1.16 nm, and a distinct hump-shaped structural domain was observed. This rough surface is likely related to the strong crystallinity of PDI-DABC.

[0163] (4) Test of charge recombination characteristics of organic solar cells

[0164] Dissociation collection rate and light intensity dependence tests were performed under the same conditions as the device's JV characteristics. Mott-Schottky and defect state densities were measured under dark conditions using a Keithley 4200SCS and CHI 600A capacitor. Three averages were used for each data point to improve data quality. CF data were acquired at 0V, and CV data were obtained at 30000Hz. The device structure is ITO / PEDOT:PSS / PM6:Y6 / electroactive violetene / Ag.

[0165] The built-in potential and moving charge density can be extracted from the voltage intercept and slope, respectively, by using C -2 Fitting is performed relative to the bias voltage in region C. C -2 And V is related to the well-known Mott-Schottky equations listed below:

[0166]

[0167] Where A is the device area; q is the elementary charge; c is the vacuum dielectric constant; ε is the dielectric constant of the organic semiconductor; N is the density of mobile charge in the device; V bi It has a built-in voltage.

[0168] Through the formulation by Walter et al., the angular frequency-dependent capacitance can be used to derive the tDOS energy distribution of a solar cell using the following formula:

[0169]

[0170] Where V bi It is the built-in electric field, C represents capacitance, ω is the angular frequency, q is the elementary charge, W is the depletion width, and V is the depletion width. bi It is the built-in potential (this value can be extracted from Mott-Schottky analysis), k B Here, ω is the Boltzmann constant, and T is the temperature in Kelvin. The applied angular frequency ω is defined by the following formula:

[0171]

[0172] Where ω0 is the attempted escape frequency. k B is Boltzmann's constant, and T is temperature in Kelvin. Only within the corresponding angular frequency range can the defect trap or emit electrons that follow the frequency change, thus increasing the capacitance.

[0173] See results Figure 8Among them, (A) the photocurrent density versus effective voltage (Jph-Veff) characteristic curves of the device; (B) the dependence of short-circuit current JSC and (C) open-circuit voltage VOC on light intensity of organic solar cells based on three violetenes; (D) the Mott-Schottky plot and (E) the defect density of states tDOS spectrum (active layer: PM6: Y6) of the device based on the violetene cathode interface layer.

[0174] (A) By measuring photocurrent density (J) ph ) and effective voltage (V eff The dependence between excitons and excitons in organic solar cells was investigated. diss ) and charge collection (P coll ) characteristics.

[0175] Based on this result, it can be seen that the P of OSC based on nitrogen-containing heterocyclic violet polymers CILs (taking DABC as an example) is... diss The values ​​(98.2%-98.6%) were all slightly higher than those of Ag-based OSC (97.4%). The P values ​​of these nitrogen-based heterocyclic violet polymer-modified OSCs were also slightly higher. coll The values ​​were significantly higher than those of naked Ag-based OSCs (PMD-DABC-, NDI-DABC-, PDI-DABC- and naked Ag-based OSCs were 87.5%, 90.7%, 89.5% and 77.8%, respectively), indicating that electroactive ionic alkenes can lead to the inhibition of bimolecular recombination and effective charge collection in OSCs.

[0176] (B) studied V OC and J SC For light intensity (P) light The dependence of J on the degree of charge recombination can be used to track the extent of charge recombination. The degree of bimolecular recombination can be measured by J. SC Formula (J) SC ∝P light α The exponential factor of α in ) is used for evaluation.

[0177] The results show that OSC without CIL produces an α of 0.987, while the incorporation of PMD-DABC, NDI-DABC, and PDI-DABC increases α to 0.990, 0.998, and 0.994, respectively, indicating a weakening of bimolecular recombination. Then, trap-assisted recombination can be determined based on V... OC Equation (V) OC ∝nkT / qlnP light (k, T, and q represent the Boltzmann constant, Kelvin temperature, and elementary charge, respectively) to describe V OC and P light The relationship between them. OSC based on bare silver provides 1.39kT q. –1The slope of the device is relatively large, while the slopes of devices containing PMD-DABC, NDI-DABC, and PDI-DABC are smaller, at 1.24kT q respectively. –1 1.06kT q –1 and 1.09kT q –1 These results demonstrate that both single-molecule and bimolecular recombination significantly mitigate the effects of electroactive violet CILs in OSCs. Among them, the NDI-DABC-based OSC exhibits the highest α and lowest n values, which strongly supports its superior PCE and stability.

[0178] (3) Estimating the V of the solar cell device using Mott-Schottky analysis bi .

[0179] Based on this result, it can be seen that the V of organic solar cells based on nitrogen-containing heterocyclic violet polymers... bi The values ​​are very similar (0.75 V, 0.74 V, and 0.73 V for PMD-DABC, NDI-DABC, and PDI-DABC-based organic solar cells, respectively). The high Vbi value of organic solar cells indicates the realization of an internal electric field that can effectively drive charge drift and reduce charge recombination. Thermal admittance spectroscopy (TAS) was used to quantitatively analyze the density of trapped states (tDOS) at different energy levels in the OSC. All devices showed similar and relatively low defect state densities in the 0.25 (0.34 eV) energy range, mainly due to fewer trapped states that trap or emit charges at high frequencies. Although the tDOS increases significantly when the energy levels of all organic solar cells are above 0.34 eV, the tDOS of NDI-DABC-based organic solar cells is much lower than that of PMD-DABC and PDI-DABC-based organic solar cells. The lower tDOS means that fewer charges are trapped in the NDI-DABC-based OSC, which can effectively reduce carrier recombination and is consistent with improved flyback firing.

[0180] In summary, this invention presents a novel nitrogen-containing heterocyclic violet polymer designed and synthesized efficiently through low-cost, metal-free quaternization polymerization. The use of nitrogen-containing heterocyclic ions facilitates the formation of strong interfacial dipoles, effectively reducing the operating functions of several metal electrodes and significantly enhancing the device's intrinsic potential, regardless of the structure of the conjugated subunits. Furthermore, altering the size of the aromatic diimide can further modulate the absorption, energy levels, self-doping, stacking behavior, crystallinity, and film morphology of the nitrogen-containing heterocyclic violet polymer interlayer, laying the foundation for further improving its conductivity, reducing recombination losses, and promoting charge transport and collection in solar cell devices. Taking the DABC series polymers as examples, the CILs of PMD-DABC, NDI-DABC, and PDI-DABC based devices on PM6:Y6 provide high PCEs of 17.06%, 17.44%, and 17.23%, respectively. The device performance exhibits considerable tolerance to CIL thickness, particularly for NDI-DABC, due to its weak absorption in the visual region, good conductivity, and ideal morphology. Furthermore, in MPP tracking tests under continuous irradiation, the device maintained over 80% of its initial PCE after 1000 hours of continuous operation. Even more impressively, when PMD-DABC, NDI-DABC, and PDI-DABC were used as CILs, the PM6:L8-BO-based OSCs offered PCEs of 17.89%, 18.43%, and 18.32%, respectively. The 18.43% represents one of the best results among binary positive OSCs. As the CIL thickness increased to 105 nm, the NDI-DABC-based OSC still offered a high PCE of 16%, the highest among all types of OSCs with interlayer thicknesses exceeding 100 nm. This work provides a completely different design principle for multifunctional ion-based CILs with an exceptionally flexible thickness fabrication range, enabling high-efficiency OSCs at low cost, demonstrating the enormous commercial potential of organic electronics.

[0181] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cathode interface layer material, characterized in that, It was prepared by a violet polymer containing phosphine and nitrogen heterocyclic cations; wherein, The phosphine-containing, nitrogen-containing heterocyclic cation-containing violet polymer is selected from any one of the compounds shown in the following structural formulas: 。 2. The cathode interface layer material according to claim 1, characterized in that, The violet polymer containing phosphine and nitrogen heterocyclic cations was synthesized according to the following synthetic route: The selection of R, N, X and Ar is as described in claim 1 for the violet polymer containing phosphine and nitrogen heterocyclic cations.

3. The cathode interface layer material according to claim 2, characterized in that, The conditions for the formation of compound 3 include: a molar ratio of compound 1 to compound 2 of 1:3-6, a reaction temperature of 80-150℃, and a reaction time of 10-40 hours; The conditions for the formation of compound 5 include: a molar ratio of compound 3 to compound 4 of 1:1 and a reaction temperature of 80-150℃.

4. An organic solar cell, characterized in that, It is prepared using the cathode interface layer material described in claim 1.

5. An organic semiconductor material, characterized in that, It is prepared using the cathode interface layer material described in claim 1.

6. A lithium-ion battery, characterized in that, It is prepared using the cathode interface layer material described in claim 1.

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