Interface modification layer material and synthesis method and application thereof

Abstract

The application relates to the technical field of photoelectric functional materials, in particular to an interface modification layer material and a synthesis method and application thereof. The interface modification layer material provided by the application increases the steric hindrance of the molecule by introducing a functional group at the para-position of the benzene ring in the BPhen molecular structure, and reduces the aggregation and crystallization of the molecule; the molecular weight of the synthesized phenanthroline derivative is large, the glass transition temperature is higher than that of BPhen, and the thermal stability of the material is better; the synthesized phenanthroline derivative exists in the form of ionized quaternary ammonium salt, the reactivity of the imine group in the molecular structure is weaker than that of BPhen or BCP, and the stability of the device is improved; and the synthesis method of the interface modification layer material provided by the application is simple, the yield is high, the purification is easy, the price is low, and the interface modification layer material can be prepared on a large scale. The interface modification layer material can be applied in a semiconductor photoelectric device, and is used as an electrode modification layer to reduce the electrode work function.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric functional materials, in particular to an interface modification layer material and a synthesis method and application thereof. Background Art

[0002] Organic semiconductor optoelectronic devices, such as organic solar cells, perovskite solar cells, and organic light-emitting diodes, currently hold broad application prospects due to their lightweight, flexible, printable, and potentially low-cost advantages. These semiconductor optoelectronic devices consist of multiple functional layers stacked in a "sandwich" structure. The charge extraction (injection) and transfer processes at the interface between these layers are crucial for achieving excellent performance and stability.

[0003] Generally speaking, these devices use low-work-function metals (such as Ca and Mg) as cathodes to extract (inject) and collect electrons. However, these low-work-function metals are relatively active and easily react chemically with water and oxygen in the air, causing device performance degradation. Studies have found that organic electrolyte materials with amino groups or quaternary ammonium salts in their side chains, such as 4,7-diphenyl-1,10-phenanthroline (BPhen), polyethyleneimine (PEI), and poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-2,7-(9,9-dioctylfluorene)] (PFN), can modify the interface of metal electrodes, greatly reducing the work function of the electrodes and effectively improving the performance of semiconductor devices (Appl. Phys. Lett., 2000, 76, 197-199; Science 2012, 336, 327-332; Nat. Photonics 2012, 6, 591-595). Among them, phenanthroline and its derivatives (such as BPhen, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline BCP) are the most commonly used interface modification layer materials and are widely used in organic light-emitting diodes and perovskite solar cell devices. However, Bphen and BCP are prone to aggregation and crystallization due to their large rigid planar molecular skeletons and strong hydrogen bond interactions between molecules (Angew.Chem., 2022, 134, e202202898). Bphen and BCP themselves have low glass transition temperatures and poor thermal stability (Chem.Mater., 2017, 29, 8299-312). In addition, the imine groups on the molecular structures of Bphen, BCP and their derivatives are prone to chemical reactions with high-performance "ADA" type fused-ring non-fullerene acceptor materials developed in recent years, resulting in decreased performance of organic solar cell devices (J.Mater.Chem.A, 2021, 9, 23269-23275).

[0004] Therefore, there is a need to further improve interface modification layer materials such as phenanthroline and its derivatives so that they can be used in the interface modification layers of semiconductor optoelectronic devices such as organic solar cells, perovskite solar cells, and organic light-emitting diodes. Summary of the Invention

[0005] In order to address the above technical deficiencies, the present invention provides an interface modification layer material, a synthesis method thereof, and an application thereof, so as to overcome the shortcomings and deficiencies of existing interface modification layer materials such as phenanthroline and its derivatives when forming an interface modification layer in semiconductor optoelectronic devices, thereby improving the performance and stability of the devices.

[0006] The present invention discloses an interface modification layer material having a molecular structure shown in the following formula I or formula II:

[0007]

[0008] Where: R1 is H or C1~C 12 Alkyl or C1~C 12 aryl groups;

[0009] R2 is C3~C 12 Branched alkyl or C3~C 12 Branched alkoxy or C6~C 12 Aryl or C6~C 12 aryloxy;

[0010] R3 is C1~C 12 Alkyl;

[0011] R4 is a C1-C6 alkyl group;

[0012] X is halogen Br or I.

[0013] A method for synthesizing an interface modification layer material having a molecular structure of Formula I or Formula II comprises the following steps:

[0014] Step 1: The R1-substituted phenanthroline derivative is subjected to a coupling reaction or an etherification reaction under palladium catalysis to obtain a R1- and R2-substituted phenanthroline derivative:

[0015]

[0016] Step 2: The phenanthroline derivatives substituted with R1 and R2 are subjected to quaternization reaction with monohalogenated alkane or dihalogenated alkane to obtain Formula I or Formula II:

[0017]

[0018] The obtained formulas I and II are interface modification layer materials.

[0019] An application of the above-mentioned interface modification layer material is that the interface modification layer material is used for the interface modification layer in semiconductor optoelectronic devices, such as organic solar cells, perovskite solar cells, organic light emitting diodes, etc.

[0020] The interface modification layer material is prepared by at least one method selected from coating, printing or evaporation to form the interface modification layer.

[0021] The thickness of the interface modification layer is 5 to 30 nm.

[0022] The present invention specifically provides an interface modification layer material having a molecular structure such as Formula III:

[0023]

[0024] The interface modification layer material represented by the above formula III can be used to prepare an interface modification layer of an organic semiconductor optoelectronic device, and the organic semiconductor optoelectronic device can be a non-fullerene organic solar cell.

[0025] Specifically, the interface modification layer can be prepared according to the following method:

[0026] (1) dissolving the interface modification layer material represented by Formula I or Formula II in an appropriate amount of alcohol solvent to prepare a 0.1-10 mg / mL solution;

[0027] The alcohol solvent is at least one of methanol, ethanol, isopropanol, n-butanol, and 2-methoxyethanol;

[0028] (2) Spin coating the solution obtained in step (1) on the active layer of an organic semiconductor optoelectronic device such as a non-fullerene organic solar cell, with a spin coating thickness of 5 to 30 nm and a rotation speed of 1000 to 5000 rpm / min.

[0029] The interface modification layer material obtained by the present invention and its synthesis method and application have the following characteristics:

[0030] Beneficial effects:

[0031] 1. In the molecular structure of BPhen, the para-grafting of the benzene ring with branched alkyl, alkoxy, aryl, aryloxy and other functional groups with large steric hindrance can weaken the hydrogen bonding effect between molecules and inhibit the aggregation and crystallization of molecules.

[0032] 2. The molecular weight of the synthesized phenanthroline derivative becomes larger, the glass transition temperature is higher than that of BPhen molecules, and the thermal stability of the material is better.

[0033] 3. The synthesized phenanthroline derivative exists in the form of quaternary ammonium salts, which are easily soluble in common polar water / alcohol solvents. When coated on the electrode surface, it will form an interfacial dipole, reducing the electrode work function. At the same time, the quaternary ammonium salt in ionic form is less reactive than the imine group in the molecular structure of BPhen or BCP, and the adverse interaction between the formed interface layer and the fused-ring non-fullerene acceptor in the active layer of the organic solar cell is suppressed, thereby improving the photoelectric conversion efficiency and device stability of the battery device.

[0034] 4. This type of interface modification layer material is simple to synthesize, has a high yield, is easy to purify, is inexpensive, and can be prepared on a large scale. It overcomes the difficulties of the existing reported interface modification layer materials, which have complex synthesis steps, are difficult to purify, and can only be prepared on a small scale in the laboratory, and is conducive to future large-scale applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the molecular structure of the product tbp-BPBr obtained in Example 1;

[0036] Figure 2 is the NMR spectrum of the product tbp-BPBr obtained in Example 1;

[0037] Figure 3 This is a graph showing the change in work function of the product tbp-BPBr obtained in Example 1 when coated on different metal surfaces;

[0038] Figure 4 The product tbp-BPBr ( Figure 4 a) and reference sample BCP ( Figure 4 b) Morphology image taken by transmission electron microscopy;

[0039] Figure 5 1 is a graph showing the glass transition temperature of the product tbp-BPBr obtained in Example 1 and the reference sample BCP;

[0040] Figure 6 2 is a current-voltage curve of a non-fullerene organic solar cell using tbp-BPBr / Ag as an electrode and a comparative cell using BCP / Ag as an electrode;

[0041] Figure 7 This is a graph showing the change in photoelectric conversion efficiency of the non-fullerene organic solar cell device with tbp-BPBr / Ag as the electrode in Example 2 and the comparative example cell device with BCP / Ag as the electrode over the storage time. DETAILED DESCRIPTION

[0042] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0043] The experimental methods involved in the following examples are conventional methods unless otherwise specified.

[0044] Unless otherwise specified, the materials, reagents, etc. used in the following examples can be commercially available products without special restrictions.

[0045] Example 1:

[0046] The present invention specifically discloses a molecular structure of an interface modification layer material as shown in Formula III:

[0047]

[0048] The interface modification layer material represented by the above formula III can be used to prepare an interface modification layer of an organic semiconductor optoelectronic device, and the organic semiconductor optoelectronic device can be a non-fullerene organic solar cell.

[0049] The synthesis method of the interface modification layer material tbp-BPBr shown in the above formula III is:

[0050] 4,7-Bis(4-bromophenyl)-1,10-phenanthroline (0.49 g, 1 mmol), 2,6-di-tert-butylphenol (0.42 g, 2 mmol), sodium tert-butoxide (0.19 g, 2 mmol), and tetrakis(triphenylphosphine)palladium (0.029 g, 0.03 mmol) were added to a round-bottom flask. 20 mL of anhydrous toluene solution was then added. The mixture was evacuated and filled with nitrogen three times, and refluxed at 110°C for 16 hours. After the reaction, the mixture was cooled to room temperature and separated by column chromatography using petroleum ether and dichloromethane as eluents to obtain the desired white product, 4,7-bis(4-(2,6-di-tert-butylphenoxy)phenyl)-1,10-phenanthroline (0.75 g, approximately 85% yield).

[0051] 4,7-bis(4-(2,6-di-tert-butylphenoxy)phenyl)-1,10-phenanthroline (0.74 g, 1 mmol) and 1,3-dibromopropane (10 mL) were dissolved in a round-bottom flask, vacuumed and filled with nitrogen three times, and the mixture was refluxed at 130 ° C for 24 hours. As the reaction proceeded, a yellow solid precipitated in the round-bottom flask. The solvent was removed by filtration, and the solid was dissolved in dichloromethane and washed three times with n-hexane to obtain the target product tbp-BPBr (0.85 g, yield of about 90%) as a yellow crystal. The H NMR spectrum of the product tbp-BPBr is as follows Figure 2 shown.

[0052] Depend on Figure 3 It can be seen that coating tbp-BPBr on the ITO and Ag surfaces can significantly reduce the work function of the electrode.

[0053] By Figure 4 The morphology chart taken by transmission electron microscope shows that the film surface of tbp-BPBr is more uniform and dense than that of the comparative sample BCP, indicating that the aggregation and crystallization of molecules are inhibited.

[0054] By Figure 5 The glass transition temperature test curve shows that the glass transition temperature of tbp-BPBr is 146.59℃, which is significantly higher than that of the comparative sample BCP (87.06℃), indicating that the thermal stability of the material is improved, and the prepared interface modification layer is also more stable.

[0055] Example 2:

[0056] A non-fullerene organic solar cell with the interface modification layer material tbp-BPBr obtained in Example 1 as the interface modification layer is prepared.

[0057] Specifically as follows:

[0058] (1) The structure of the reference cell device is ITO / PEDOT:PSS (4083) / PM6:Y6 / BCP / Ag, and the device structure with tbp-BPBr / Ag as the electrode is ITO / PEDOT:PSS (4083) / PM6:Y6 / tbp-BPBr / Ag. Among them, PM6 is a high-performance polymer donor reported in the literature (Adv. Mater., 2015, 27, 4655-4660), and Y6 is a high-performance non-fullerene acceptor reported in the literature (Joule, 2019, 3, 1140-1151). A layer of PEDOT:PSS (CLEVIOSTM PVP A1 4083) hole transport layer with a thickness of 35 nm is spin-coated on the surface of the cleaned ITO glass. The pre-configured active layer solution (PM6 and Y6 with a mass ratio of 1:1.2, a mass concentration of 16.5 mg / mL of chloroform solution, and 0.5% by volume of 1-chloronaphthalene as an additive) is dynamically spin-coated on the substrate surface to obtain a PM6:Y6 active layer film with a thickness of about 100 nm.

[0059] (2) The interface modification layer material tbp-BPBr obtained in Example 1 is dissolved in methanol to obtain a solution with a concentration of 1.0 mg / mL, and then spin-coated on the PM6:Y6 active layer at a speed of 3000 rpm / min to obtain an interface modification layer with a thickness of about 10 nm. In the reference device, the concentration of the BCP methanol solution is 1 mg / mL.

[0060] (3) Finally, 100 nm of Ag is evaporated as a metal top electrode to complete the preparation of the cell device. The pressure in the vacuum chamber during metal evaporation is <5×10 -4 Pa, and the evaporation rate is 4 A / s.

[0061] The current-voltage curves of the non-fullerene organic solar cell with tbp-BPBr / Ag as the electrode and the reference cell with BCP / Ag as the electrode are shown in Figure 1, and the specific performance parameters are shown in Table 1. Figure 6

[0062] Table 1 is the performance parameters of the non-fullerene organic solar cell with tbp-BPBr / Ag as the electrode and the reference cell with BCP / Ag as the electrode:

[0063]

[0064] From Figure 6 and Table 1, the open-circuit voltage V OC , short-circuit current J SC and fill factor FF of the non-fullerene organic solar cell with tbp-BPBr / Ag as the electrode are all improved to a certain extent compared with the reference cell with BCP / Ag as the electrode, and the photoelectric conversion efficiency of the cell is improved. More importantly, Figure 7 The T 80 of the cell device with tbp-BPBr / Ag as the electrode under the glove box storage environment is 2270h, which is much better than that of the reference device (T 80 = 203h), and the T 80 indicates the time required for the photoelectric conversion efficiency of the device to decay to 80% of the initial value. Therefore, the application provides a high-efficiency and stable interface modification layer material, which can be successfully used in semiconductor optoelectronic devices such as organic solar cells or perovskite solar cells.

[0065] It is worth mentioning that the non-fullerene and other technical features involved in the present patent application should be regarded as prior art, and the specific structure, working principle and possible characterization and testing methods of these technical features can be selected by the person skilled in the art, which should not be regarded as the invention point of the present patent. The present patent will not be further described in detail.

[0066] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present application. Any simplification, modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application, without departing from the technical solution of the present application, are still within the scope of the technical solution of the present application.​

Claims

1. An interface modification layer material, characterized by: It has the molecular structure shown in the following formula II: Wherein: R1 is H; R2 is C6~C 12 aryloxy; R4 is a C1-C6 alkyl group; X is halogen Br or I.

2. A method for synthesizing the interface modification layer material according to claim 1, characterized in that: The steps include: Step 1: The R1-substituted phenanthroline derivative is subjected to a coupling reaction or an etherification reaction under palladium catalysis to obtain a R1- and R2-substituted phenanthroline derivative: Step 2: quaternize the phenanthroline derivative substituted with R1 and R2 with a dihalogenated alkane to obtain Formula II: The obtained formula II is the interface modification layer material.

3. An application of the interface modification layer material according to claim 1, characterized in that: Interface modification layer materials are used for interface modification layers in semiconductor optoelectronic devices.

4. The application of the interface modification layer material according to claim 3, characterized in that: The interface modification layer material is prepared by at least one method selected from coating, printing or evaporation to form the interface modification layer.

5. The application of the interface modification layer material according to claim 3, characterized in that: The thickness of the interface modification layer is 5 to 30 nm.

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