Preparation method and application of benzoylhydrazide perylene diimide electron transport layer

Abstract

The present invention discloses the preparation and application of a benzoylhydrazide perylene diimide electron transport layer. The benzoylhydrazide group is used to coordinately regulate the bay area and amide position of perylene diimide, which effectively solves many common problems faced by electron transport layers, such as poor stability, low electron mobility and energy level mismatch. The benzoylhydrazide group and the aminoalkyl side chain give the material good solution processing performance, strong self-doping characteristics, thickness insensitivity and work function reduction ability. Nitrogen-containing hydrazine and secondary amine groups can form hydrogen bonds with other molecules or ions under certain circumstances, enhance intermolecular interactions and improve the photothermal stability of the material. In addition, after the bay area is modified with the benzoylhydrazide group, it can effectively inhibit molecular aggregation, regulate crystallinity and form a good thin film morphology. Ultimately, the energy conversion efficiency of the organic solar cell prepared with this electron transport layer reached 15.87%.

Description

Technical Field

[0001] The present invention relates to the technical field of electron transport layers of organic solar cells, and in particular to a preparation method and application of a benzoylhydrazide perylene diimide electron transport layer. Background Art

[0002] Against the backdrop of a rapidly advancing global economy and sustained population growth, the demand for energy is growing. However, the use of traditional fossil fuels not only leads to severe air pollution and greenhouse gas emissions, but also has limited reserves, making it difficult to meet the long-term needs of human development. As the core driving force for economic and social development, energy is directly related to the prosperity and decline of a country's economy and social stability.

[0003] Organic solar cells are an emerging renewable energy technology. They offer significant cost-effectiveness and can be mass-produced through solution processing. Furthermore, their flexibility and bendability allow them to be used in innovative products such as wearable devices and building-integrated solar cells. These applications offer broad potential, making them a key development area within solar technology and attracting significant attention.

[0004] Thanks to the long-term and tireless efforts of numerous researchers, significant progress has been made in the development of organic solar cells. Through innovative device structural design, in-depth mechanism research, breakthroughs in material development, and optimized interface engineering, the power conversion efficiency (PCE) of organic solar cells in single-junction devices has approached 20%. However, compared to inorganic silicon solar cells, their efficiency still needs to be improved.

[0005] As a key component of organic solar cells, the electron transport layer (ETL) can improve interfacial contact, induce carrier transport, regulate interfacial work function, and isolate water and oxygen, significantly impacting the performance of organic solar cells. Currently, researchers have developed a series of highly efficient n-type organic semiconductor materials, including perylene diimide-based ETLs. However, some perylene diimide-based ETLs often contain hydrophilic polar side chains that are susceptible to corrosion by water and oxygen, or, due to their high surface energy, form poor interfacial contact with the active layer, negatively impacting energy conversion efficiency and device stability. Furthermore, the highly coplanar perylene diimide core is prone to excessive molecular aggregation, resulting in a rough interfacial morphology and a high electron extraction barrier, limiting further improvements in the performance of organic solar cells. Therefore, it is necessary to develop efficient and stable ETLs based on perylene diimide. Summary of the Invention

[0006] The present invention provides a preparation method and application of a benzoylhydrazide perylene diimide electron transport layer, which utilizes the benzoylhydrazide group to synergistically regulate the bay area and amide position of the perylene diimide, effectively solving many common problems faced by electron transport layers, such as poor stability, low electron mobility, and energy level mismatch.

[0007] The technical solution adopted by the present invention is as follows: a benzoylhydrazide perylene diimide electron transport layer having a structure shown in Formula 1, as follows:

[0008]

[0009] Formula 1.

[0010] Another technical solution of the present invention is as follows: a benzoylhydrazide perylene diimide electron transport layer containing a structure shown in Formula I, comprising the following steps:

[0011] Step 1: Synthesis of dibromoperylene diimide PDINN-2Br containing an amine alkyl side chain:

[0012] (1) 1,7-Dibromo-3,4,9,10-perylenetetracarboxylic dianhydride (0.550 g, 1 mmol) and N,N-dimethyl-dipropyl-triamine (1.592 g, 10 mmol) were weighed and placed in a 250 mL round-bottom flask. 40 mL of anhydrous methanol was added as the solvent.

[0013] Since 1,7-dibromo-3,4,9,10-perylenetetracarboxylic dianhydride contains bromine, the reaction needs to be protected from light, so the outer periphery of the round-bottom flask needs to be wrapped with tin foil. After the reaction apparatus is set up, the inside of the flask is evacuated with a vacuum pump, and then nitrogen is introduced to ensure a sealed environment to prevent interference from outside air.

[0014] Then, the temperature of the heated stirrer was set to 70 °C, and the stirring bar was started to stir to achieve sufficient dissolution of the reactants and thus achieve a uniform mixing effect; then, condensed water was connected and heated under reflux for 8 h, and the completion of the reaction was confirmed by thin-layer chromatography monitoring;

[0015] (2) After the reaction is completed, a red-black liquid is obtained. Subsequently, the experimental apparatus is disassembled and the flask is removed. The reaction mixture is allowed to cool to room temperature, and the liquid is placed in a 50 mL heart-shaped flask. Methanol is removed by rotary evaporation at 64 °C to obtain a red-black solid substance.

[0016] (3) Extract with deionized water and chloroform. The volume of water used for extraction can be twice the volume of chloroform. Repeat 3 times until the water layer becomes clear and transparent. Combine the collected red organic layers, add an appropriate amount of anhydrous magnesium sulfate to remove the remaining water, stir and let stand, filter and remove the magnesium sulfate; put the liquid into a 50 mL chicken heart bottle, set the rotary evaporator temperature to 60 ° C and remove the chloroform under reduced pressure to obtain a red-black solid crude product;

[0017] (4) The red-black solid crude product was dissolved in 3 mL of dichloromethane and added dropwise into a beaker containing 400 mL of n-hexane. The mixture was stirred with a magnetic stirrer for 24 h to remove residual N,N-dimethyl-dipropyl-triamine. The solid product was filtered and dried in a vacuum drying oven for two days to obtain the intermediate product PDINN-2Br.

[0018] Step 2: Synthesis of a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN;

[0019] (1) PDINN-2Br (0.499 g, 0.6 mmol) and 4-(dimethylamino)benzoylhydrazide (0.645 g, 3.6 mmol) were weighed and added to a 50 mL round-bottom flask. 20 mL of N,N-dimethylformamide (DMF) was added as solvent and the flask was wrapped with tin foil to protect from light. After the reaction apparatus was set up, the inside of the flask was evacuated with a vacuum pump and then nitrogen was introduced to protect the flask. Ensure a sealed environment to prevent interference from outside air.

[0020] Then, the temperature of the heating stirrer was set to 130 °C, and the stirring bar was started to stir to fully dissolve the reactants and achieve a uniform mixing effect; then, condensed water was added and heated under reflux for 8 h, and the reaction was confirmed to be complete by thin-layer chromatography monitoring;

[0021] (2) After the reaction is complete, the solution turns dark purple. Disassemble the apparatus, remove the flask, and wait for the product to cool to room temperature. Then, set up a vacuum distillation apparatus and distill the reaction solution at 120 °C for 5 h to remove the solvent DMF. Finally, a purple-black solid residue is obtained.

[0022] (3) Extraction with deionized water and chloroform, with the volume of water used for extraction being twice that of chloroform, was repeated three times until the aqueous layer became clear and transparent. The collected purple organic layers were combined, and an appropriate amount of anhydrous magnesium sulfate was added to remove the remaining water. After stirring, the mixture was allowed to stand and filtered. The filtrate was placed in a 50 mL heart-shaped bottle. The chloroform solvent was removed under reduced pressure on a rotary evaporator set at 60 °C to obtain a purple-black solid crude product.

[0023] (4) The purple-black solid crude product was dissolved in 3 mL of dichloromethane and then transferred to a beaker containing 400 mL of n-hexane solution. A magnetic stirrer was started to stir for 24 h to remove residual 4-(dimethylamino)benzoylhydrazide. The solid product was filtered and dried in a vacuum drying oven for two days to obtain the purple solid final product PDINN-NOPN.

[0024] Furthermore, an organic solar cell device with a benzoylhydrazide perylene diimide electron transport layer is specifically:

[0025] The invention comprises an ITO glass layer, a PEDOT:PSS layer arranged on the ITO glass layer, an active layer arranged on the PEDOT:PSS layer, a benzoylhydrazide perylene diimide electron transport layer arranged on the active layer, and an Ag electrode arranged on the benzoylhydrazide perylene diimide electron transport layer.

[0026] Furthermore, a synthesis method of a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN is provided. The specific synthesis route reaction equation is as follows:

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

[0028] (1) The present invention provides a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN, which has a simple synthesis process and can obtain the product in only two steps. It can also achieve high conductivity and high electron mobility, and environmentally friendly water / alcohol solubility.

[0029] (2) The hydrazine group in benzoylhydrazide and the secondary amine group in the aminoalkyl side chain can play a good n-type doping role. These nitrogen-containing groups can provide additional electrons to the electron-deficient groups, which can achieve the effect of balancing carriers and improving conductivity. In addition, it can effectively induce the generation of interface dipoles, significantly reducing the work function of the metal electrode, helping to achieve matching arrangement of interface energy levels and lowering the interface electron injection barrier.

[0030] (3) After the benzoylhydrazide group is introduced into the bay area of ​​perylene diimide, a suitable torsion angle is formed, which improves the originally planar molecular structure and inhibits molecular aggregation. It can effectively inhibit molecular aggregation, regulate crystallinity and form a good film morphology.

[0031] (4) Nitrogen-containing hydrazine and secondary amine groups can form hydrogen bonds with other molecules or ions under certain circumstances, enhancing intermolecular interactions and improving the photothermal stability of the material. At the same time, PDINN-NOPN also exhibits excellent interface regulation. It reduces the surface energy of the electron transport layer, improves the interfacial compatibility with the active layer, and achieves coordinated regulation of film morphology and electron mobility.

[0032] (5) In order to study the performance of PDINN-NOPN electron transport layer devices, PDINN-NOPN and classic PDINN were used as electron transport layers in organic solar cell devices. The results showed that the device based on PDINN-NOPN electron transport layer achieved an energy conversion efficiency of 15.87%, which was significantly higher than the 14.83% of organic solar cell devices based on PDINN. In addition, the open circuit voltage, short circuit current density and fill factor were all improved simultaneously, reflecting that the benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN is more compatible with the energy levels of the electrode and active layer, and has good charge transfer ability, which promotes the efficient transmission and collection of carriers.

[0033] (6) Benzoylhydrazide groups and aminoalkyl side chains give the material good solution processing properties, strong self-doping properties, thickness insensitivity and the ability to reduce work function. Nitrogen-containing hydrazide and secondary amine groups can form hydrogen bonds with other molecules or ions under certain circumstances, enhancing intermolecular interactions to improve the photothermal stability of the material. In addition, after the bay area is modified with benzoylhydrazide groups, it can effectively inhibit molecular aggregation, regulate crystallinity and form a good film morphology. PDINN-NOPN and PDINN were used as electron transport layers to prepare devices with PM6:Y6 as active layers for performance testing (results are shown in the attached figure). Figure 4 Then the corresponding external quantum efficiency (EQE) test was carried out to verify the accuracy of the JV curve test (see Appendix Figure 5 ). Compared with the open circuit voltage (V OC ) is 0.68 V, the short-circuit current density (J SC ) is 25.27 mA / cm 2 , the fill factor (FF) is 68.71%, the power conversion efficiency (PCE) is 14.83%, and the performance of the device based on PDINN-NOPN has been improved. OC 0.70 V, J SC 26.16 mA / cm 2 , FF is 71.09% and PCE is 15.87%. In addition, the EQE test shows that the device based on PDINN-NOPN has a higher integrated current density than the corresponding PDINN device, which is 24.62 mA / cm 2 , the latter is 24.15 mA / cm 2 The research results show that PDINN-NOPN is a potential electron transport layer material. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a structural diagram of a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN of the present invention.

[0035] Figure 2 The present invention provides a specific synthesis route for the benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN.

[0036] Figure 3 The device structure diagram of a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN based on the present invention.

[0037] Figure 4 This is the JV curve of the organic solar cell with PDINN-NOPN as the cathode interface layer of the present invention.

[0038] Figure 5 This is the EQE curve of the organic solar cell with PDINN-NOPN as the cathode interface layer of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings.

[0040] The reaction of the present invention is shown in the attached figure, and the specific reaction steps are as follows: Synthesis steps of a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN:

[0041] Step 1: Synthesis of dibromoperylene diimide PDINN-2Br containing an amine alkyl side chain:

[0042] (1) Weigh 1,7-dibromo-3,4,9,10-perylene tetracarboxylic dianhydride (0.550 g, 1 mmol) and N,N-dimethyl-dipropyl-triamine (1.592 g, 10 mmol) into a 250 mL round-bottom flask, and add 40 mL of anhydrous methanol as the solvent. Since 1,7-dibromo-3,4,9,10-perylene tetracarboxylic dianhydride contains bromine, it needs to be protected from light during the reaction, so the outer periphery of the round-bottom flask needs to be wrapped with tin foil. After the reaction apparatus is set up, the inside of the flask is evacuated with a vacuum pump, and then nitrogen is introduced for protection. Ensure a sealed environment to prevent external air from entering and interfering. Then, the temperature of the heating stirrer is set to 70 °C, and the stirring bar is started to stir to achieve full dissolution of the reactants and thus achieve a uniform mixing effect. Then, the condensed water is connected and heated under reflux for 8 h. The reaction is confirmed to be complete by thin-layer chromatography monitoring.

[0043] (2) After the reaction is complete, a reddish-black liquid is obtained. Subsequently, the experimental apparatus is disassembled and the flask is removed. After the reaction mixture cools to room temperature, the liquid is placed in a 50 mL heart-shaped flask. Methanol is removed by rotary evaporation at 64 °C to obtain a reddish-black solid.

[0044] (3) Extract with deionized water and chloroform. The volume of water used for extraction can be twice the volume of chloroform. Repeat three times until the aqueous layer becomes clear and transparent. Combine the collected red organic layers, add an appropriate amount of anhydrous magnesium sulfate to remove the remaining water, stir, let stand, and filter to remove the magnesium sulfate. The liquid is placed in a 50 mL heart-shaped flask. Set the rotary evaporator temperature to 60 °C and remove the chloroform under reduced pressure to obtain a reddish-black solid crude product.

[0045] (4) The reddish-black crude solid product was dissolved in 3 mL of dichloromethane and added dropwise to a beaker containing 400 mL of n-hexane. The mixture was stirred with a magnetic stirrer for 24 h to remove residual N,N-dimethyl-dipropyl-triamine. The solid product was filtered and dried in a vacuum oven for two days to obtain the intermediate product, PDINN-2Br.

[0046] Step 2: Synthesis of a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN.

[0047] (1) PDINN-2Br (0.499 g, 0.6 mmol) and 4-(dimethylamino)benzoylhydrazide (0.645 g, 3.6 mmol) were weighed and added to a 50 mL round-bottom flask. 20 mL of N,N-dimethylformamide (DMF) was added as solvent and the flask was wrapped with tin foil to protect from light. After the reaction apparatus was set up, the inside of the flask was evacuated with a vacuum pump and then nitrogen was introduced for protection. Ensure a sealed environment to prevent interference from external air. Then, the temperature of the heating stirrer was set to 130 °C, and the stirring bar was started to stir to fully dissolve the reactants and achieve a uniform mixing effect. Then, condensed water was connected and heated under reflux for 8 h. The reaction was confirmed to be complete by thin-layer chromatography monitoring.

[0048] (2) After the reaction is complete, the solution turns dark purple. Disassemble the apparatus, remove the flask, and wait for the product to cool to room temperature. Then, set up a vacuum distillation apparatus and distill the reaction solution at 120 °C for 5 h to remove the solvent DMF. Finally, a purple-black solid residue is obtained.

[0049] (3) Extract with deionized water and chloroform. The volume of water used for extraction is twice the volume of chloroform. Repeat 3 times until the water layer becomes clear and transparent. Combine the collected purple organic layers, add appropriate amount of anhydrous magnesium sulfate to remove the remaining water, stir and let stand, filter, and pour the filtrate into a 50 mL chicken heart flask. Set the rotary evaporator temperature to 60 °C and remove the solvent chloroform under reduced pressure to obtain a purple-black solid crude product.

[0050] (4) Dissolve the crude purple-black solid product in 3 mL of dichloromethane, transfer it to a beaker containing 400 mL of n-hexane solution, and stir it with a magnetic stirrer for 24 h to remove residual 4-(dimethylamino)benzoylhydrazide. Filter the solid product and dry it in a vacuum drying oven for two days to obtain the purple solid final product, PDINN-NOPN.

[0051] An organic solar cell device with a benzoylhydrazide perylene diimide electron transport layer, specifically:

[0052] The invention comprises an ITO glass layer, a PEDOT:PSS layer arranged on the ITO glass layer, an active layer arranged on the PEDOT:PSS layer, a benzoylhydrazide perylene diimide electron transport layer arranged on the active layer, and an Ag electrode arranged on the benzoylhydrazide perylene diimide electron transport layer.

[0053] Table 1 Photovoltaic performance of organic solar cells based on PM6:Y6 as active layer with different cathode interface layers.

[0054]

[0055] J SC a Integrated current density refers to the value obtained by integrating the current density generated by a solar cell within a certain wavelength range. This value can reflect the energy conversion efficiency of the solar cell across the entire spectrum.

[0056] The beneficial effects of the present invention are as follows: first, the perylene diimide is modified by the aminoalkyl side chain and the benzoylhydrazide group, giving the material environmentally friendly water / alcohol processing, which is beneficial to the large-scale production and preparation of subsequent devices. Secondly, after the perylene diimide bay area is modified by the benzoylhydrazide group, molecular aggregation is suppressed, the molecular crystallinity is balanced, and a dense and uniform film morphology is formed. In addition, the hydrazine group and the secondary amine group can form hydrogen bonds, and the interaction between the intermolecular hydrogen bonds can greatly improve the photothermal stability of the material and slow down the aging and degradation rate of the material in the environment. Finally, the hydrazine group in the benzoylhydrazide and the secondary amine group of the aminoalkyl side chain can play a good n-type doping role, reduce the interface barrier, and facilitate the extraction and transmission of electrons. As a result, the recombination of electrons in the interface layer is significantly reduced, thereby increasing the open circuit voltage and short-circuit circuit density of the device, and ultimately allowing the PDINN-NOPN-based electron transport layer device.

Claims

1. A benzoylhydrazide perylene diimide electron transport layer having the structure shown in Formula 1, characterized in that: as follows:

2. A benzoylhydrazide perylene diimide electron transport layer according to claim 1, comprising a method for preparing a benzoylhydrazide perylene diimide electron transport layer having a structure shown in Formula I, comprising the following steps: Step 1: Synthesis of dibromoperylene diimide PDINN-2Br containing an amine alkyl side chain: (1) Weigh 1,7-dibromo-3,4,9,10-perylenetetracarboxylic dianhydride (0.550 g, 1 mmol) and N,N-dimethyl-dipropyl-triamine (1.592 g, 10 mmol) into a 250 mL round-bottom flask and add 40 mL of anhydrous methanol as solvent; Since 1,7-dibromo-3,4,9,10-perylenetetracarboxylic dianhydride contains bromine, the reaction needs to be protected from light, so the outer periphery of the round-bottom flask needs to be wrapped with tin foil. After the reaction apparatus is set up, the inside of the flask is evacuated with a vacuum pump, and then nitrogen is introduced to ensure a sealed environment to prevent interference from outside air. Then, the temperature of the heated stirrer was set to 70°C, and the stirring bar was started to stir to achieve sufficient dissolution of the reactants and thus achieve a uniform mixing effect; then, condensed water was connected and heated under reflux for 8 hours, and the completion of the reaction was confirmed by thin layer chromatography monitoring; (2) After the reaction is completed, a red-black liquid is obtained. Subsequently, the experimental apparatus is disassembled and the flask is removed. The reaction mixture is allowed to cool to room temperature, and the liquid is placed in a 50 mL heart-shaped flask. Methanol is removed by rotary evaporation at 64°C to obtain a red-black solid substance. (3) Extract with deionized water and chloroform. The volume of water used for extraction can be twice the volume of chloroform. Repeat 3 times until the water layer becomes clear and transparent. Combine the collected red organic layers, add an appropriate amount of anhydrous magnesium sulfate, remove the remaining water, stir and let stand, filter and remove the magnesium sulfate; put the liquid into a 50 mL chicken heart bottle, set the rotary evaporator temperature to 60 ° C and remove the chloroform under reduced pressure to obtain a red-black solid crude product; (4) The reddish-black solid crude product was dissolved in 3 mL of dichloromethane and added dropwise into a beaker containing 400 mL of n-hexane. The mixture was stirred with a magnetic stirrer for 24 h to remove residual N,N-dimethyl-dipropyl-triamine. The solid product was filtered and dried in a vacuum drying oven for two days to obtain the intermediate product PDINN-2Br. Step 2: Synthesis of a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN; (1) PDINN-2Br (0.499 g, 0.6 mmol) and 4-(dimethylamino)benzoylhydrazide (0.645 g, 3.6 mmol) were weighed and added to a 50 mL round-bottom flask. 20 mL of N,N-dimethylformamide (DMF) was added as solvent and the flask was wrapped with tin foil to protect from light. After the reaction apparatus was set up, the inside of the flask was evacuated with a vacuum pump and then nitrogen was introduced to protect the flask. Ensure a sealed environment to prevent interference from outside air. Then, the temperature of the heating stirrer was set to 130°C, and the stirring bar was started to stir to fully dissolve the reactants and achieve a uniform mixing effect; then, condensed water was added and heated under reflux for 8 hours, and the reaction was confirmed to be complete by thin layer chromatography monitoring; (2) After the reaction is completed, the solution turns dark purple. The flask is removed from the apparatus and the product is allowed to cool to room temperature. A vacuum distillation apparatus is then constructed and the reaction solution is subjected to vacuum distillation at 120°C for 5 h to remove the solvent DMF. Finally, a purple-black solid residue is obtained. (3) Extraction with deionized water and chloroform, with the volume of water used for extraction being twice that of chloroform, was repeated three times until the aqueous layer became clear and transparent. The collected purple organic layers were combined, and an appropriate amount of anhydrous magnesium sulfate was added to remove the remaining water. After stirring, the mixture was allowed to stand and filtered. The filtrate was placed in a 50 mL heart-shaped bottle. The chloroform solvent was removed under reduced pressure on a rotary evaporator set at 60°C to obtain a purple-black solid crude product. (4) The purple-black solid crude product was dissolved in 3 mL of dichloromethane, then transferred to a beaker containing 400 mL of n-hexane solution and stirred with a magnetic stirrer for 24 h; The purpose is to remove residual 4-(dimethylamino)benzoylhydrazide; filter and dry the solid product in a vacuum drying oven for two days to obtain a purple solid final product PDINN-NOPN.

3. The benzoylhydrazide perylene diimide electron transport layer according to claim 1, characterized in that: Organic solar cell devices with electron transport layers, specifically: The invention comprises an ITO glass layer, a PEDOT:PSS layer arranged on the ITO glass layer, an active layer arranged on the PEDOT:PSS layer, a benzoylhydrazide perylene diimide electron transport layer arranged on the active layer, and an Ag electrode arranged on the benzoylhydrazide perylene diimide electron transport layer.

4. The method for synthesizing a benzoylhydrazide perylene diimide electron transport layer PDINN-NOPN according to claim 1, wherein the specific synthetic route reaction equation is as follows:

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