Naphthalimide cathode interface material and preparation method and application thereof
By introducing amine compounds at both ends of the naphthalimide backbone to form a two-sided NDI derivative, the problem of insufficient performance of existing cathode interface materials is solved, achieving efficient electron transport and interface matching, and improving the efficiency and stability of organic solar cells.
Patent Information
- Application Number
- CN202511000580.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-18
- Publication Date
- 2025-10-31
AI Technical Summary
Existing cathode interface materials have insufficient performance in organic solar cells, making it difficult to achieve efficient electron transport and interface matching, which affects device efficiency and stability.
By introducing different types of amine compounds as substituents at both ends of the naphthalene imide (NDI) backbone to form a bilateral NDI derivative, the molecular stacking mode and film morphology are controlled, the LUMO energy level position is precisely adjusted, and the energy level matching with the non-fullerene acceptor and cathode electrode is optimized.
It improves the efficiency and stability of organic solar cells, with a device efficiency of up to 19.39%, exhibiting higher electron mobility and lower carrier recombination rate, and enhancing Voc and FF.
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Figure CN120865198A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of organic semiconductor materials technology, and more specifically, to a naphthalimide-based cathode interface material, its preparation method, and its application. Background Technology
[0002] With the rapid development of the global economy, the consumption of traditional fossil fuels such as coal, oil, and natural gas is accelerating, leading to energy shortages and environmental pollution, which have become major challenges to sustainable human development. In the search for clean energy alternatives, solar energy, as an inexhaustible and renewable energy source, has received widespread attention. Organic solar cells, due to their unique advantages such as light weight, low cost, and the ability to be fabricated into flexible devices, have stood out among numerous solar energy technologies and are considered one of the most promising next-generation solar cell technologies.
[0003] In organic solar cells (OSCs), the cathode interface layer, as a key functional layer in the device structure, is typically located between the photoactive layer and the metal cathode, undertaking multiple important functions. Its main functions include efficiently and selectively extracting and transporting electrons, preventing hole injection and recombination, regulating the energy level matching between the electrode and the active layer, and optimizing the electric field distribution within the device. Devices modified with a cathode interface typically exhibit significantly better photoelectric performance than unmodified devices. By introducing suitable cathode interface materials, the cathode work function can be effectively reduced, achieving better energy level matching, thereby promoting efficient electron extraction and transport, preventing hole back-injection, and suppressing interface recombination. Furthermore, the interface modification layer can optimize interface contact quality, reduce interface defects, improve carrier lifetime and fill factor, ultimately significantly improving the device's open-circuit voltage (Voc), short-circuit current density (Jsc), and power conversion efficiency (PCE).
[0004] However, traditional cathode interface materials such as zinc oxide (ZnO), titanium dioxide (TiO2), and polymer materials PFN (or PFN-Br) still have many limitations in practical applications. Developing cathode interface layer materials with better performance, tunable structure, low-temperature processing, and good interfacial compatibility with active layer materials has become one of the key research directions for improving the efficiency and stability of organic solar cells.
[0005] In recent years, naphthalene diimide (NDI) derivatives have become a hot topic in the research of novel n-type organic semiconductor materials due to their unique molecular structure and excellent photoelectric properties. The NDI-N series uses naphthalene diimide (NDI) as the core backbone and modifies its side chains. Their molecular structures typically contain nitrogen-containing substituents (such as amino groups, quaternary ammonium salts, etc.). Compared to structures modified from the NDI core, their synthesis is relatively simple, usually involving only imidization reactions. The steps are concise, the yield is high, and the long alkyl chains can enhance the solution processability of the molecule, improve film quality, and the side chains can inhibit excessive crystallization and enhance amorphous states, which is beneficial for forming ideal phase-separated structures. Introducing functional groups can regulate interfacial properties; for example, charged groups (quaternary ammonium salts) can regulate electronic polarization and dipole moments, thereby reducing the electrode work function and improving interfacial contact. The NDI unit itself has a strong electron-withdrawing ability, and its low LUMO energy level matches well with the LUMO energy levels of non-fullerene acceptors and polymer donors, thus promoting efficient electron transport from the active layer to the cathode. Furthermore, nitrogen-containing substituents (such as quaternary ammonium salts) can reduce the cathode work function and electron injection barrier by forming interfacial dipoles, while simultaneously enhancing contact with the metal electrode. Compared to traditional ETL, NDI derivative materials exhibit higher electron mobility, lower carrier recombination rate, and superior interfacial contact performance, significantly improving electron extraction efficiency, increasing Voc and FF, and further driving the improvement of device PCE.
[0006] Therefore, a novel naphthalimide-based cathode interface material is provided, which not only helps to deepen the understanding of electron transport and interface engineering in organic photovoltaic devices, but also provides strong technical support and theoretical basis for the commercialization of high-efficiency, long-life, and low-cost organic solar cells. Summary of the Invention
[0007] To achieve the above objectives, this application provides a naphthalimide-based cathode interface material, its preparation method, and its applications. The naphthalimide-based cathode interface material provided by this invention is a bilateral NDI derivative formed by introducing substituents at both ends of the NDI backbone; the substituents are amine compounds. By limiting the types of substituents introduced, this invention effectively controls the molecular stacking mode, film morphology, and crystallization behavior, precisely adjusting its lowest unoccupied molecular orbital (LUMO) energy level position to achieve better energy level matching with mainstream non-fullerene acceptors and cathode electrodes. The naphthalimide-based cathode interface material provided by this invention is a high-performance organic photovoltaic material, and the efficiency of organic solar cell devices assembled with it can reach up to 19.39%.
[0008] The first objective of this invention is to provide a naphthalimide-based cathode interface material. To achieve this objective, this invention provides the following technical solution:
[0009] A naphthalimide-based cathode interface material, wherein the naphthalimide-based cathode interface material is a bilateral NDI derivative formed by introducing substituents at both ends of an NDI backbone, and has the following general structural formula:
[0010] Where R1 and R2 are any of the following structural formulas:
[0011]
[0012] The second objective of this invention is to provide a method for preparing the above-mentioned naphthalimide-based cathode interface material.
[0013] To achieve this objective, the present invention provides the following technical solution:
[0014] A method for preparing a naphthalimide-based cathode interface material: Naphthalene tetracarboxylic anhydride is added to N,N-dimethylformamide and heated to 100–120°C. An amine compound is then added at this temperature to react with the mixture. After cooling, deionized water is added, followed by separation and extraction with ethyl acetate. The organic phase is then collected, dried, and rotary evaporated to obtain a crude product. The crude product is purified by silica gel column chromatography to obtain the target product. The amine compound is any one or any two of 3-morpholinopropane-1-amine, N-isopropyl-1,3-propanediamine, N,N-dibutyl-1,3-propanediamine, 3-(pyrimidin-2-yl)propane-1-amine, and 3-(pyridin-3-yl)propane-1-amine.
[0015] Furthermore, the ratio of N,N-dimethylformamide to naphthalenetetracarboxylic anhydride is 60–100 mL: 1 g.
[0016] Furthermore, the molar ratio of the amine compound to naphthalenetetracarboxylic anhydride is 1 to 6:1.
[0017] Furthermore, the reaction time is 8–10 hours.
[0018] Furthermore, the ratio of deionized water to naphthalene tetracarboxylic anhydride is 100-150 mL: 1 g; the ratio of ethyl acetate to naphthalene tetracarboxylic anhydride is 100-150 mL: 1 g.
[0019] Furthermore, the eluent used for silica gel column chromatography purification was n-hexane and ethyl acetate in a volume ratio of 20:1.
[0020] A third objective of this invention is to provide the application of the above-mentioned naphthalimide cathode interface materials in organic solar cells.
[0021] The technical solution provided in this application has at least the following advantages compared to the prior art:
[0022] 1. This invention forms a bilateral NDI derivative by introducing different types of substituents at both ends of the NDI backbone. The substituents are amine compounds. This derivative can effectively control the molecular stacking mode, film morphology, and crystallization behavior, and can also precisely adjust its lowest unoccupied molecular orbital (LUMO) energy level, thereby achieving better energy level matching with mainstream non-fullerene acceptors and cathode electrodes. It is a high-performance organic photovoltaic material, and the organic solar cell device assembled from it can achieve an efficiency of up to 19.39%.
[0023] 2. The synthesis method provided by this invention is simple and effective. The structure and morphology of the prepared naphthalimide-based cathode interface material are controllable, and its stability and reproducibility are good. When applied to photovoltaic devices, the naphthalimide-based cathode interface material provided by this invention can effectively improve the efficiency and stability of the devices. Attached Figure Description
[0024] Figure 1 The NMR spectrum of NDI-2NO prepared in Example 1;
[0025] Figure 2 The NMR spectrum of NDI-2N-C2 prepared in Example 2;
[0026] Figure 3 The NMR spectrum of NDI-2N-C4 prepared in Example 3;
[0027] Figure 4 This is a schematic diagram of the structure of the organic solar cell prepared in Example 4;
[0028] Figure 5 This is a schematic diagram of the structure of the organic solar cell prepared in Comparative Example 1;
[0029] Figure 6 The JV curves are for the battery devices of Examples 4-6 and Comparative Examples 1-2.
[0030] Figure 7 External quantum efficiency diagrams of the battery devices in Examples 4-6 and Comparative Examples 1-2. Detailed Implementation
[0031] To enable those skilled in the art to better understand this application, the following detailed description is provided in conjunction with embodiments and accompanying drawings. However, it should be understood that the following embodiments are merely preferred embodiments of this application, and the scope of protection claimed in this application shall be determined by the scope defined in the claims.
[0032] In the description of this invention, it should be noted that unless specific conditions are specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0033] <Example>
[0034] Example 1
[0035] This embodiment provides a naphthalimide-based cathode interface material, which has the following structure:
[0036]
[0037] The reaction equations for the above-mentioned naphthalimide-based cathode interface materials are shown below:
[0038]
[0039] The above-mentioned naphthalimide-based cathode interface materials were prepared using the following method:
[0040] In a 50 mL round-bottom flask, naphthalenetetracarboxylic anhydride (300 mg, 1.12 mmol) dissolved in 30 mL DMF was added. The mixture was heated to 100 °C, and 3-morpholinopropane-1-amine (161.33 mg, 1.12 mmol) and N-isopropyl-1,3-propanediamine (130.00 mg, 1.12 mmol) were added. The mixture was reacted at 100 °C for 10 h. After the reaction was complete, 50 mL of water was added to the reaction mixture, and the mixture was extracted three times with 50 mL of ethyl acetate. The organic phase was then collected, dried, and rotary evaporated to obtain the crude product. The crude product was further purified by silica gel column chromatography using n-hexane:ethyl acetate = 20:1 (V / V). The final product was named NDI-2NO. The NMR spectrum of NDI-2NO is shown below. Figure 1 As shown.
[0041] Example 2
[0042] This embodiment provides a naphthalimide-based cathode interface material, which has the following structure:
[0043]
[0044] The reaction equations for the above-mentioned naphthalimide-based cathode interface materials are shown below:
[0045]
[0046] The above-mentioned naphthalimide-based cathode interface materials were prepared using the following method:
[0047] In a 50 mL round-bottom flask, naphthalenetetracarboxylic anhydride (300 mg, 1.12 mmol) dissolved in 30 mL DMF was added. The mixture was heated to 120 °C, and N-isopropyl-1,3-propanediamine (779.98 mg, 6.71 mmol) was added. The reaction was carried out at 120 °C for 10 h. After the reaction was completed, 50 mL of water was added to the reaction mixture, and the mixture was extracted three times with 50 mL of ethyl acetate. The organic phase was then collected, dried, and rotary evaporated to obtain the crude product. The crude product was further purified by silica gel column chromatography using n-hexane:ethyl acetate = 20:1 (V / V). The final product was named NDI-2N-C2. 1 H-NMR such as Figure 2 As shown.
[0048] Example 3
[0049] This embodiment provides a naphthalimide-based cathode interface material, which has the following structure:
[0050]
[0051] The reaction equations for the above-mentioned naphthalimide-based cathode interface materials are shown below:
[0052]
[0053] The above-mentioned naphthalimide-based cathode interface materials were prepared using the following method:
[0054] In a 50 mL round-bottom flask, naphthalenetetracarboxylic anhydride (300 mg, 1.12 mmol) dissolved in 30 mL DMF was added. The mixture was heated to 120 °C, and N,N-dibutyl-1,3-propanediamine (1.25 g, 6.71 mmol) was added. The reaction was carried out at 120 °C for 8 h. After the reaction was completed, 50 mL of water was added to the reaction mixture, and the mixture was extracted three times with 50 mL of ethyl acetate. The organic phase was then collected, dried, and rotary evaporated to obtain the crude product. The crude product was further purified by silica gel column chromatography using n-hexane:ethyl acetate = 20:1 (V / V). The final product was named NDI-2N-C4. 1 H-NMR such as Figure 3 As shown.
[0055] Example 4
[0056] Example 4 provides an organic solar cell device modified with the naphthalimide-based cathode interface material NDI-2NO prepared in Example 1. The structure of the organic solar cell is as follows: Figure 4As shown, from bottom to top, it includes a glass substrate, an ITO conductive electrode, a hole transport layer, a photoactive layer, an NDI-type cathode interface layer, and a metal electrode layer (Ag). Its fabrication method is as follows:
[0057] Step 1: Spin-coat a hole transport layer (2PACz) with a concentration of 0.3 mg / mL onto a glass substrate / ITO. The active layer material is D18:L8:BO, the ratio of D18:L8:BO is 1:1.2, and the concentration is 5 mg / mL based on D18.
[0058] Step 2: Dissolve the cathode interface material (NDI-2NO) prepared in Example 1 in methanol to form a 1 mg / mL cathode interface layer solution, and spin-coat the cathode interface layer solution onto the active layer to form an NDI-type cathode interface layer.
[0059] Step 3: Deposit a silver electrode on the NDI-type cathode interface layer.
[0060] Example 5
[0061] This embodiment 5 provides an organic solar cell device modified with the naphthalimide cathode interface material NDI-2N-C2 prepared in embodiment 2. The difference between this embodiment and embodiment 4 is that the naphthalimide cathode interface material used is NDI-2N-C2 instead of NDI-2NO. All other aspects are the same as in embodiment 4.
[0062] Example 6
[0063] This embodiment 6 provides an organic solar cell device modified with the naphthalimide cathode interface material NDI-2N-C4 prepared in embodiment 3. The difference between this embodiment and embodiment 4 is that the naphthalimide cathode interface material used is NDI-2N-C4 instead of NDI-2NO. All other aspects are the same as in embodiment 4.
[0064] Comparative Example 1
[0065] This comparative example provides an organic solar cell device, the structure of which is as follows: Figure 5 As shown, from bottom to top, it includes a glass substrate, an ITO conductive electrode, a hole transport layer, a photoactive layer, and a metal electrode layer (Ag). The preparation method differs from Example 4 in that the cathode interface layer solution is not spin-coated; all other aspects are the same.
[0066] Comparative Example 2
[0067] This comparative example provides an organic solar cell device modified with a naphthalimide-based cathode interface material. The difference between this device and Example 4 lies in the structural formula of the naphthalimide-based cathode interface material, which is as follows:
[0068] Named NDI-N, all others are the same.
[0069] Performance testing
[0070] The battery device performance, JV curves, and external quantum efficiency of Examples 4-6 and Comparative Examples 1-2 were tested respectively. The battery device performance test results are shown in Table 1; the JV curves are shown in... Figure 6 As shown, the external quantum efficiency is as Figure 7 As shown.
[0071] Table 1
[0072]
[0073] As shown in Table 1, compared with the battery device data of Comparative Example 1, the battery devices of Examples 4-6 clearly have superior performance compared to the battery device without the added cathode interface transport layer; compared with the battery device data of Comparative Example 2, the battery devices of Examples 4-6 also outperform the battery performance of Comparative Example 2. This indicates that the naphthalimide-based cathode interface materials prepared in Examples 1-3 have potential application value in organic solar cells.
[0074] Depend on Figure 6 and Figure 7 It can be seen that, compared with Comparative Examples 1-2, the devices in Examples 4-6 have higher photoelectric conversion efficiency, indicating that the cathode interface material of the present invention provides better interface modification for the device.
Claims
1. A naphthalimide-based cathode interface material, characterized in that, The naphthalimide-based cathode interface material is a bilateral NDI derivative formed by introducing substituents at both ends of the NDI backbone, and it has the following general structural formula: Where R1 and R2 are any of the following structural formulas:
2. The naphthalimide-based cathode interface material according to claim 1, characterized in that, R1 is R2 is 3. The method for preparing the naphthalimide-based cathode interface material according to claim 1 or 2, characterized in that, The preparation method involves adding naphthalenetetracarboxylic anhydride to N,N-dimethylformamide, heating to 100–120°C, and then adding an amine compound at this temperature to react. After cooling, deionized water is added, followed by separation and extraction with ethyl acetate. The organic phase is then collected, dried, and rotary evaporated to obtain a crude product. The crude product is purified by silica gel column chromatography to obtain the target product. The amine compound is any one or any two of 3-morpholinopropane-1-amine, N-isopropyl-1,3-propanediamine, N,N-dibutyl-1,3-propanediamine, 3-(pyrimidin-2-yl)propane-1-amine, and 3-(pyridin-3-yl)propane-1-amine.
4. The method for preparing the naphthalimide-based cathode interface material according to claim 3, characterized in that, The ratio of N,N-dimethylformamide to naphthalenetetracarboxylic anhydride is 60–100 mL: 1 g.
5. The method for preparing the naphthalimide-based cathode interface material according to claim 3, characterized in that, The molar ratio of amine compounds to naphthalenetetracarboxylic anhydride is 1 to 6:
1.
6. The method for preparing the naphthalimide-based cathode interface material according to claim 3, characterized in that, The reaction time is 8 to 10 hours.
7. The method for preparing the naphthalimide-based cathode interface material according to claim 3, characterized in that, The ratio of deionized water to naphthalenetetracarboxylic anhydride is 100-150 mL: 1 g.
8. The method for preparing the naphthalimide-based cathode interface material according to claim 3, characterized in that, The ratio of ethyl acetate to naphthalenetetracarboxylic anhydride is 100–150 mL: 1 g.
9. The method for preparing the naphthalimide-based cathode interface material according to claim 3, characterized in that, The eluent used for silica gel column chromatography purification was n-hexane and ethyl acetate in a volume ratio of 20:
1.
10. The application of the naphthalimide cathode interface material according to claim 1 or 2 in organic solar cells.