A class of bifunctional phosphonic acid self-assembled molecules, their preparation and applications

Abstract

This invention belongs to the field of optoelectronic material preparation and application, and discloses a class of bifunctional phosphonic acid self-assembled molecules, their preparation and application. The self-assembled molecule has a structure as shown in one of general formulas A-1 to A-4, wherein the R1 and R2 groups are independently selected from groups containing lone pairs of electrons. This invention modifies the molecular structure by introducing groups R1 and R2 (e.g., benzaldehyde, methyl sulfone, benzyl oxy) containing lone pairs of electrons to form new self-assembled molecules while retaining the phosphonic acid groups. The resulting phosphonic acid self-assembled molecules possess both hole carrier transport function and perovskite interface defect passivation function, exhibiting bifunctionality.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic material preparation and application, and more specifically, relates to a class of bifunctional phosphonic acid self-assembled molecules, their preparation and application. These phosphonic acid self-assembled molecules can replace the hole transport layer in perovskite light-emitting diode devices, and passivate while transporting charge carriers, thus exhibiting bifunctional characteristics. Background Technology

[0002] Perovskite light-emitting diodes (PeLEDs) have become a key research focus in the field of display luminescence due to their narrower emission spectral bands, higher color purity, and more easily adjustable light color compared to traditional display technologies. Among them, PeLEDs prepared by thermal evaporation exhibit high reliability and are more likely to be compatible with existing OLED production lines, making them a promising technology for industrial application. Among the functional layers that determine device performance, hole transport and interface modification layers play crucial roles. However, most mature hole transport layer materials are suitable for solution-based methods. Perovskite materials prepared by these methods are limited by spin-coating processes, leading to uneven film formation. In contrast, perovskite materials obtained by thermal evaporation achieve uniform film preparation by controlling the precursor evaporation rate. Furthermore, they offer advantages such as tunable bandgap and adjustable light color. However, existing mature hole transport materials, limited by band structure and carrier transport efficiency, do not meet the requirements of thermally evaporated PeLEDs. This results in the relatively low overall performance of PeLEDs prepared by thermal evaporation at present, particularly in terms of efficiency and brightness. Therefore, there is an urgent need to develop a new multifunctional hole transport material system suitable for thermally evaporated PeLEDs.

[0003] Self-assembled molecules (SAMs), as small organic molecules, achieve bonding with metal oxides through special functional groups, such as phosphonic acids and carboxylic acids. Compared with traditional hole transport materials, SAMs and metal oxide substrates (e.g., ITO) are more tightly and firmly bonded through covalent bonds, thus providing a more efficient carrier transport channel for PeLEDs. However, numerous interface defects at the buried interface between the SAMs layer and the perovskite layer inhibit the overall performance of PeLEDs, and current research on the buried interface between the SAMs layer and the perovskite light-emitting layer is relatively lacking. Therefore, designing and fabricating bifunctional SAM molecules suitable for thermally evaporated PeLEDs that simultaneously satisfy the "anchoring effect" with the substrate and the "passivation effect" with the perovskite at the buried interface can not only improve device performance but also simplify the PeLED fabrication process, possessing significant scientific and technological value and promising industrial application prospects. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a class of bifunctional phosphonic acid self-assembled molecules, their preparation, and applications. By modifying the molecular structure, groups R1 and R2 (e.g., benzaldehyde, methyl sulfone, benzyl oxy) containing lone pairs of electrons are introduced while retaining the phosphonic acid groups to form a new self-assembled molecule. The resulting phosphonic acid self-assembled molecule possesses both hole carrier transport and perovskite interface defect passivation functions, exhibiting dual functionality. It can simultaneously replace both the hole transport material and passivating agent in PeLEDs, performing both hole transport and passivation functions. PeLEDs prepared based on this novel self-assembled molecule can effectively improve the defect state density at the interface, thereby enhancing device brightness and efficiency, achieving performance comparable to commercially available NiO-based PeLEDs. x The efficiency of the PVK composite hole transport layer structure device is improved, while the brightness is also significantly enhanced.

[0005] To achieve the above objectives, according to one aspect of the present invention, a bifunctional phosphonic acid self-assembled molecule is provided, characterized in that the self-assembled molecule has a structure as shown in one of general formulas A-1 to A-4:

[0006]

[0007] The R1 and R2 groups are independently selected from groups containing lone pairs of electrons.

[0008] As a further preferred embodiment of the present invention, the R1 and R2 groups are independently selected from: benzaldehyde, methyl sulfone, and benzoxy.

[0009] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned bifunctional phosphonic acid self-assembled molecule, characterized in that,

[0010] When the self-assembled molecule has a structure as shown in one of general formulas A-2 to A-4, and R1 and R2 are the same, the preparation method includes the following steps:

[0011] (1) Using the 3,7-dibromophenazine derivative shown in Formula 1 as a raw material, and combined with the dibromoethane shown in Formula 2, a nucleophilic substitution reaction was carried out to obtain the 3,7-dibromo-bromoethyl-phenazine intermediate 3 shown in Formula 3;

[0012] The reaction formula is:

[0013]

[0014] Where X is oxygen, sulfur, or selenium;

[0015] (2) The intermediate 3 obtained in step (1) is subjected to an Arbuzov reaction with triethyl phosphonate to obtain the phenazine intermediate 4 containing diethyl phosphonate as shown in Formula 4.

[0016] The reaction formula is:

[0017]

[0018] (3) Using the borate ester derivative shown in Formula 5, intermediate 4 obtained in step (2) undergoes a Suzuki reaction to obtain diethyl phosphonate phenazine intermediate 6 with an R1 group; wherein, the R1 group in Formula 5 is benzaldehyde, methyl sulfone or benzoxy; the molar ratio of compound 5 to compound 4 is greater than or equal to 2:1.

[0019] The reaction formula is:

[0020]

[0021] (4) Use bromotrimethylsilane to hydrolyze intermediate 6 to obtain a bifunctional phosphonic acid self-assembled molecule.

[0022] When the self-assembled molecule has a structure as shown in general formula A-1, and R1 and R2 are the same, the preparation method includes the following steps:

[0023] (1) Using 3,6-dibromocarbazole as shown in Formula 1 as a raw material, and combining it with dibromoethane as a raw material shown in Formula 2, a nucleophilic substitution reaction is carried out to obtain 3,6-dibromo-bromoethyl-carbazole intermediate 3 as shown in Formula 3;

[0024] The reaction formula is:

[0025]

[0026] Where X is oxygen, sulfur, or selenium;

[0027] (2) The intermediate 3 obtained in step (1) is subjected to an Arbuzov reaction with triethyl phosphonate to obtain carbazole intermediate 4 with diethyl phosphonate as shown in Formula 4.

[0028] The reaction formula is:

[0029]

[0030] (3) Using the borate ester derivative shown in Formula 5, intermediate 4 obtained in step (2) undergoes a Suzuki reaction to obtain carbazole intermediate 6 with an R1 group; wherein, the R1 group in Formula 5 is benzaldehyde, methyl sulfone or benzoxy; the molar ratio of compound 5 to compound 4 is greater than or equal to 2:1.

[0031] The reaction formula is:

[0032]

[0033] (4) Use bromotrimethylsilane to hydrolyze intermediate 6 to obtain a bifunctional phosphonic acid self-assembled molecule.

[0034] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned bifunctional phosphonic acid self-assembled molecule, characterized in that,

[0035] When the self-assembled molecule has a structure as shown in one of general formulas A-2 to A-4, and R1 and R2 are different, the preparation method includes the following steps:

[0036] S1. Using the 3,7-dibromophenazine derivative shown in Formula 1 as a raw material, and combining it with the dibromoethane shown in Formula 2, a nucleophilic substitution reaction is carried out to obtain the 3,7-dibromo-bromoethyl-phenazine intermediate 3 shown in Formula 3;

[0037] The reaction formula is:

[0038]

[0039] Where X is oxygen, sulfur, or selenium;

[0040] S2. The intermediate 3 obtained in step S1 is subjected to an Arbuzov reaction with triethyl phosphonate to obtain the phenazine intermediate 4 containing diethyl phosphonate as shown in Formula 4.

[0041] The reaction formula is:

[0042]

[0043] S3. Using the borate ester derivative shown in Formula 5, intermediate 4 obtained in step S2 undergoes a Suzuki reaction to obtain diethyl phosphonate phenazine intermediate 7 with an R1 group; wherein, the R1 group in Formula 5 is benzaldehyde, methyl sulfone, or benzoxy; the molar ratio of compound 5 to compound 4 is less than or equal to 1:1 and greater than or equal to 0.5:1.

[0044] The reaction formula is:

[0045]

[0046] S4. The intermediate 7 obtained in S3 is subjected to a Suzuki reaction using the borate ester derivative shown in Formula 5' to obtain a diethyl phosphonate phenazine intermediate 8 with R1 and R2 groups; wherein, the R2 group in Formula 5' is selected from benzaldehyde, methyl sulfone, and benzoxy, and is different from the R1 group; the molar ratio of the compound of Formula 5' to the compound of Formula 7 is greater than or equal to 1:1;

[0047] The reaction formula is:

[0048]

[0049] S5. Using bromotrimethylsilane to hydrolyze intermediate 8 yields a bifunctional phosphonic acid self-assembled molecule.

[0050] When the self-assembled molecule has a structure as shown in general formula A-1, and R1 and R2 are different, the preparation method includes the following steps:

[0051] S1. Using 3,6-dibromocarbazole as shown in Formula 1 as a raw material, and combining it with dibromoethane as a raw material shown in Formula 2, a nucleophilic substitution reaction is carried out to obtain 3,6-dibromo-bromoethyl-carbazole intermediate 3 as shown in Formula 3;

[0052] The reaction formula is:

[0053]

[0054] Where X is oxygen, sulfur, or selenium;

[0055] S2. The intermediate 3 obtained in step S1 is subjected to an Arbuzov reaction with triethyl phosphonate to obtain carbazole intermediate 4 containing diethyl phosphonate as shown in Formula 4.

[0056] The reaction formula is:

[0057]

[0058] S3. Using the borate ester derivative shown in Formula 5, intermediate 4 obtained in step S2 undergoes a Suzuki reaction to obtain carbazole diethyl phosphonate intermediate 7 with an R1 group; wherein, the R1 group in Formula 5 is benzaldehyde, methyl sulfone, or benzoxy; the molar ratio of compound 5 to compound 4 is less than or equal to 1:1 and greater than or equal to 0.5:1.

[0059] The reaction formula is:

[0060]

[0061] S4. The intermediate 7 obtained from S3 is subjected to a Suzuki reaction using the borate ester derivative shown in Formula 5' to obtain a carbazole diethyl phosphonate intermediate 8 with R1 and R2 groups; wherein, the R2 group in Formula 5' is selected from benzaldehyde, methyl sulfone, and benzoxy, and is different from the R1 group; the molar ratio of the compound of Formula 5' to the compound of Formula 7 is greater than or equal to 1:1;

[0062] The reaction formula is:

[0063]

[0064] S5. Intermediate 8 is hydrolyzed using bromotrimethylsilane to obtain a bifunctional phosphonic acid self-assembled molecule.

[0065] As a further preferred embodiment of the present invention, in step (1) or step S1, the nucleophilic substitution reaction is carried out in a solvent system with the participation of tetrabutylammonium bromide and a base. Specifically, 3,6-dibromocarbazole raw material, dibromoethane raw material, tetrabutylammonium bromide, base and solvent are added to the reaction apparatus, and then air is purged using a protective gas. Then, the mixture is heated to reflux under the protection of the protective gas. After the reaction is complete, it is cooled to room temperature for purification and post-treatment to obtain 3,6-dibromo-bromoethyl-carbazole intermediate 3.

[0066] Alternatively, the nucleophilic substitution reaction is carried out in a solvent system with the participation of tetrabutylammonium bromide and a base. Specifically, the 3,7-dibromophenazine derivative raw material, dibromoethane raw material, tetrabutylammonium bromide, base and solvent are added to the reaction apparatus, and then the air is purged with a protective gas. Then, the reaction is heated to reflux under the protection of the protective gas. After the reaction is complete, it is cooled to room temperature for purification and post-treatment to obtain 3,7-dibromo-bromoethyl-phenazine intermediate 3.

[0067] The protective gas is nitrogen or argon; the base is an inorganic base, preferably potassium hydroxide; and the solvent is deionized water.

[0068] Preferably, the molar ratio of 3,6-dibromocarbazole, dibromoethane, tetrabutylammonium bromide, and the base to the volume of the solvent satisfies 1 mmol: 1-2 mmol: 0.1-0.3 mmol: 3-5 mmol: 5-10 ml; the molar ratio of 3,7-dibromophenazine derivative, dibromoethane, tetrabutylammonium bromide, and the base to the volume of the solvent satisfies 1 mmol: 1-2 mmol: 0.1-0.3 mmol: 3-5 mmol: 5-10 ml; and the reaction time under reflux is 24-48 hours.

[0069] As a further preferred embodiment of the present invention, in step (2) or step S2, the Arbuzov reaction is carried out in a solvent system. Specifically, 3,6-dibromo-bromoethyl-carbazole intermediate 3 and triethyl phosphonate are added to the reaction apparatus, air is purged using a protective gas, and then the reaction is heated to reflux under protective gas protection. After the reaction is complete, it is cooled to room temperature for purification and post-treatment to obtain carbazole intermediate 4 containing diethyl phosphonate.

[0070] Alternatively, the Arbuzov reaction is carried out in a solvent system. Specifically, 3,7-dibromo-bromoethyl-phenazine intermediate 3 and triethyl phosphonate are added to the reaction apparatus, air is purged using a protective gas, and then the reaction is heated to reflux under protective gas protection. After the reaction is complete, it is cooled to room temperature for purification and post-processing to obtain phenazine intermediate 4 containing diethyl phosphonate.

[0071] The protective gas is nitrogen or argon.

[0072] Preferably, the molar ratio of 3,6-dibromo-bromoethyl-carbazole intermediate 3 to triethyl phosphonate is 1 mmol: 1-1.5 mmol; the molar ratio of 3,7-dibromo-bromoethyl-phenazine intermediate 3 to triethyl phosphonate is 1 mmol: 1-1.5 mmol; and the reaction time under reflux is 24-48 hours.

[0073] As a further preferred embodiment of the present invention, in step (4) or step S5, the hydrolysis reaction specifically involves adding intermediate 6, bromotrimethylsilane, and dioxane into the reaction apparatus, using a protective gas to purge the air, and then heating to reflux under the protection of the protective gas. After the reaction is complete, the mixture is cooled to room temperature, deionized water is added, the mixture is stirred, and filtered to obtain a bifunctional phosphonic acid self-assembled molecule.

[0074] Alternatively, the hydrolysis reaction specifically involves adding intermediate 8, bromotrimethylsilane, and dioxane into a reaction apparatus, purging the air with a protective gas, heating to reflux under protective gas conditions, cooling to room temperature after the reaction is complete, adding deionized water, stirring, and filtering to obtain a bifunctional phosphonic acid self-assembled molecule.

[0075] The protective gas is nitrogen or argon.

[0076] Preferably, the molar ratio of intermediate 6 and bromotrimethylsilane to the volume of dioxane satisfies 1 mmol: 1-2 mmol: 10 ml; the molar ratio of intermediate 8 and bromotrimethylsilane to the volume of dioxane satisfies 1 mmol: 1-2 mmol: 10 ml; the reaction time under reflux is 48-72 hours; the amount of deionized water added is at least twice the volume of dioxane, and the stirring time is 2 hours.

[0077] As a further preferred embodiment of the present invention, in step (3), the Suzuki reaction is carried out in a solvent system. Specifically, intermediate 4, the borate ester derivative shown in Formula 5, palladium catalyst, base, ethanol, water and toluene are mixed, air is purged using a protective gas, and the reaction is heated under reflux under the protection of the protective gas. After cooling to room temperature, purification treatment is performed to obtain diethyl phosphonate carbazole intermediate 6 with R1 group.

[0078] Alternatively, the Suzuki reaction is carried out in a solvent system, specifically by mixing intermediate 4, the borate ester derivative shown in Formula 5, palladium catalyst, base, ethanol, water, and toluene, purging air with a protective gas, heating and refluxing under protective gas protection, cooling to room temperature, and then purifying to obtain diethyl phosphonate phenazine intermediate 6 with the R1 group.

[0079] The protective gas is nitrogen or argon; the palladium catalyst is preferably tetra(triphenylphosphine)palladium; and the base is preferably potassium carbonate.

[0080] Preferably, the molar ratio of intermediate 4, the borate ester derivative shown in Formula 5, tetra(triphenylphosphine)palladium, and potassium carbonate to the volume ratio of ethanol, water, and toluene satisfies the following: 1 mmol: 2-2.5 mmol: 0.04-0.06 mmol: 2 mmol: 1 ml: 1 ml: 2 ml; and the reaction time of the heating reflux reaction is 12-48 hours.

[0081] As a further preferred embodiment of the present invention, in step S3, the Suzuki reaction is carried out in a solvent system. Specifically, intermediate 4, the borate ester derivative shown in Formula 5, palladium catalyst, base, ethanol, water, and toluene are mixed, air is purged using a protective gas, and the reaction is heated under reflux under the protection of the protective gas. After cooling to room temperature, purification treatment is performed to obtain diethyl phosphonate carbazole intermediate 7 with R1 group.

[0082] Alternatively, the Suzuki reaction is carried out in a solvent system, specifically by mixing intermediate 4, the borate ester derivative shown in Formula 5, palladium catalyst, base, ethanol, water, and toluene, purging air with a protective gas, heating and refluxing under protective gas protection, cooling to room temperature, and then purifying to obtain diethyl phosphonate phenazine intermediate 6 with the R1 group.

[0083] The protective gas is nitrogen or argon; the palladium catalyst is preferably tetra(triphenylphosphine)palladium; and the base is preferably potassium carbonate.

[0084] Preferably, the molar ratio of intermediate 4, the borate ester derivative shown in Formula 5, tetra(triphenylphosphine)palladium, and potassium carbonate to the volume ratio of ethanol, water, and toluene satisfies the following: 1 mmol: 0.5-1 mmol: 0.02-0.05 mmol: 2 mmol: 1 ml: 1 ml: 2 ml; and the reaction time of the heating reflux reaction is 12-48 hours.

[0085] In step S4, the Suzuki reaction is carried out in a solvent system. Specifically, intermediate 7, the borate ester derivative shown in formula 5', palladium catalyst, base, ethanol, water and toluene are mixed, air is purged using a protective gas, and the reaction is heated under reflux under the protection of the protective gas. After cooling to room temperature, purification treatment is performed to obtain diethyl phosphonate carbazole intermediate 8 with R1 and R2 groups.

[0086] Alternatively, the Suzuki reaction is carried out in a solvent system, specifically by mixing intermediate 7, the borate ester derivative shown in Formula 5', a palladium catalyst, a base, ethanol, water, and toluene, purging the air with a protective gas, heating and refluxing under a protective gas atmosphere, cooling to room temperature, and then purifying to obtain diethyl phosphonate phenazine intermediate 8 with R1 and R2 groups.

[0087] The protective gas is nitrogen or argon; the palladium catalyst is preferably tetra(triphenylphosphine)palladium; and the base is preferably potassium carbonate.

[0088] Preferably, the molar ratio of intermediate 7, the borate ester derivative shown in Formula 5', tetra(triphenylphosphine)palladium, and potassium carbonate to the volume ratio of ethanol, water, and toluene satisfies the following: 1 mmol: 1-1.5 mmol: 0.02-0.05 mmol: 2 mmol: 1 ml: 1 ml: 2 ml; and the reaction time of the heating reflux reaction is 12-48 hours.

[0089] According to another aspect of the present invention, the present invention provides the application of a multifunctional layer formed based on the above-mentioned bifunctional phosphonic acid self-assembled molecules as a substitute for a hole transport layer in a perovskite light-emitting diode device, wherein the multifunctional layer is capable of transporting charge carriers and acting as a passivation layer; wherein the multifunctional layer is located between the metal oxide electrode and the perovskite light-emitting layer and is in direct contact with the metal oxide electrode and the perovskite light-emitting layer, and the perovskite material is lead-based perovskite.

[0090] As a further preferred embodiment of the present invention, the application can improve the external quantum efficiency and / or increase the brightness of the perovskite light-emitting diode device.

[0091] As a further preferred embodiment of the present invention, the perovskite light-emitting diode device comprises, in sequence: a metal oxide electrode, a multifunctional layer, a perovskite light-emitting layer, an electron transport layer, an electron injection layer, and a cathode;

[0092] Preferably, the multifunctional layer is a monolayer; the perovskite in the perovskite luminescent layer is prepared by thermal evaporation; the electron transport layer is selected from TPBi, TmPyPB, and C. 60 The cathode is an Al electrode.

[0093] More preferably, the thickness of the perovskite light-emitting layer is between 10-200 nm, the thickness of the electron transport layer is between 15-70 nm, and the thickness of the cathode is between 50-200 nm.

[0094] Compared with the prior art, the phosphonic acid self-assembled molecule obtained by the present invention has a general structure as shown in one of the general formulas A-1 to A-4, with R1 and R2 groups having lone pair electrons (e.g., benzaldehyde, methyl sulfone, benzyl oxy group). This phosphonic acid self-assembled molecule as a whole possesses both hole transport and perovskite passivation effects, exhibiting dual functionality. It can replace the traditional hole transport and passivator composite layer in perovskite light-emitting diodes (especially thermally evaporated perovskite light-emitting diodes), serving as a multifunctional layer at the buried interface of PeLEDs, reducing the thickness of the buried interface layer, and thus improving the luminous efficiency and brightness of PeLEDs. In this invention, the bifunctional phosphonic acid self-assembled molecule can be anchored to metal oxide substrates (such as ITO) on the one hand, and has a passivation effect with perovskite on the other hand, achieving a tighter interlayer bonding, constructing a continuous carrier transport channel, and thus improving the overall performance of the electroluminescent device.

[0095] The bifunctional self-assembled molecule of this invention can simultaneously replace the hole transport material and passivator in PeLEDs, playing both hole transport and passivation roles, significantly reducing the thickness of the buried interface. Furthermore, due to the interaction between the multifunctional layer and the metal oxide substrate (such as ITO) and the light-emitting layer, the continuity of the carrier transport channel is significantly improved, reducing carrier transport losses between interfaces. This synergistic effect further enhances the carrier transport efficiency during PeLED operation, thereby contributing to improved brightness and external quantum efficiency. The phosphonic acid self-assembled molecule obtained in this invention has a general structure as shown in one of the general formulas A-1 to A-4, where the R1 and R2 groups have lone pair electrons (e.g., benzaldehyde, methyl sulfone, benzyl oxy group), and are para-attached to the benzene ring in the general formula. These self-assembled molecules with carbazole or phenazine groups retain the advantages of high hole selectivity, fast hole transfer rate, and low interfacial well state density of carbazole and phenazine groups, while also incorporating a variety of functionalized groups, further enhancing their superiority as multifunctional layers at buried interfaces. PeLEDs fabricated based on these novel self-assembled molecules can effectively improve the defect state density at the interface, thereby improving device brightness and efficiency, achieving performance comparable to commercially available NiO-based peLEDs. x The efficiency of the PVK composite hole transport layer structure device is improved, while the brightness is also significantly enhanced.

[0096] The bifunctionalized phosphonic acid self-assembled molecule of this invention possesses excellent optoelectronic properties, serving as a multifunctional layer at the buried interface in perovskite optoelectronic devices. On one hand, the phosphonic acid groups can chemically bond with the metal oxide substrate (e.g., indium tin oxide, ITO), resulting in a stronger bond between the two functional layers; on the other hand, the functionalized terminal groups can bind to uncoordinated Pb in the perovskite. 2+ Mutual coordination suppresses the generation of defects in the perovskite layer, thereby effectively improving the device performance of perovskite light-emitting diodes.

[0097] This invention further expands the role of carbazole (phenazine) self-assembled molecules in PeLEDs by introducing groups containing lone pairs of electrons (e.g., benzaldehyde, methylbenzene sulfone, benzyloxy) as functionalizing groups. The benzene ring in the three functionalizing groups is used to avoid the shift between the highest occupied molecular orbital (HOMO) and the maximum valence band (VBM) of the perovskite caused by the decrease in dipole moment. The C=O, S=O, and OMe groups attached to the benzene ring connect to the Pb in the perovskite luminescent layer through their lone pairs of electrons. 2+The molecules coordinate with each other to achieve interface passivation. As demonstrated in the examples below, bifunctional phosphonic acid self-assembled molecules are suitable for PeLEDs with a wide range of emission peaks, covering most of the blue and green regions. This also illustrates the broad application range of such bifunctional phosphonic acid self-assembled molecules. However, traditional hole transport layer / passivator composite layers suffer from interfacial contact problems, leading to losses during carrier transport. Therefore, replacing the composite layer with a single-molecule multifunctional layer helps to construct continuous carrier transport channels, thereby improving carrier transport efficiency and achieving higher device brightness and performance.

[0098] The bifunctionalized phosphonic acid self-assembled molecule obtained in this invention serves as a multifunctional layer to replace the original hole transport layer in thermally evaporated perovskite light-emitting diodes (LEDs). This reduces the thickness of the buried interface layer and utilizes the interaction between the bifunctionalized groups and the metal oxide substrate (such as ITO) and the light-emitting layer to construct continuous carrier transport channels. Simultaneously, it serves to transport holes and passivate defects at the buried interface. Furthermore, when the self-assembled molecule of this invention is used as a multifunctional layer at the buried interface, the process is simple and convenient, significantly reducing device fabrication costs.

[0099] Specifically, the present invention can achieve the following beneficial effects:

[0100] (1) The bifunctionalized phosphonic acid self-assembled molecule of the present invention has selected functional groups R1 and R2 containing lone pairs of electrons (e.g., benzaldehyde, methyl sulfone, benzyl oxy), which have a larger electron cloud distribution and can effectively interact with uncoordinated Pb in perovskite. 2+ Therefore, the introduction of bifunctional phosphonic acid self-assembled molecules as a multifunctional layer at the buried interface of PeLED can play a dual anchoring role (the other anchoring role comes from phosphonic acid), firmly connecting the substrate and the light-emitting layer, making hole transport more efficient.

[0101] (2) The bifunctional phosphonic acid self-assembled molecules of this invention can be applied to perovskite light-emitting diode devices in a layer structure with a single-molecule thickness (i.e., the thickness of the multifunctional layer is a single molecule thickness), compared to traditional hole transport materials (NPB, NiO). x The devices obtained based on this invention (such as PVK) exhibit higher brightness. Furthermore, the fabrication process for the multifunctional layer is simple, making it more suitable for large-scale industrial production.

[0102] (3) The bifunctional phosphonic acid self-assembled molecules obtained in this invention can be applied to most blue-green PeLED devices prepared by thermal evaporation. This is mainly due to the fact that after bonding with metal oxide substrates (such as ITO), their deep VBM (around -6.0 eV) matches these blue-green perovskite light-emitting layers. This versatility is of great significance for the industrial production of optoelectronic devices.

[0103] Considering that the anchoring effect between commonly used self-assembled molecules and metal oxides can be disrupted by highly polar solvents (such as dimethyl sulfoxide), their application in solution methods is limited. This invention uses a vapor deposition method instead of the traditional solution method to prepare the perovskite light-emitting layer, avoiding the use of highly polar solvents, enhancing the uniformity of the multifunctional layer, thereby maximizing the effect of self-assembled molecules and improving the device performance of PeLEDs. Attached Figure Description

[0104] Figure 1 This is a schematic diagram of the PeLED device structure; the “hole transport layer (SAMs)” refers to the “multifunctional layer” in each device embodiment or the “traditional hole transport layer” in the comparative sample.

[0105] Figure 2 This diagram illustrates the interaction mechanism between the bifunctionalized phosphonic acid self-assembled molecule of this invention and the ITO substrate and perovskite layer when used as a multifunctional layer material; the R groups in the diagram are R1 and R2 groups.

[0106] Figure 3 The diagrams show the geometric configurations of compounds 1-1 to 4-6. The three-dimensional spatial structure of each compound and the sites of its functionalized groups are visible in the diagrams.

[0107] Figure 4 Compounds 1-1 to 1-6 and NiO from Device Example 1 x / PVK (comparison sample) External quantum efficiency-current density relationship characteristic curve of thermally evaporated perovskite blue light device.

[0108] Figure 5 Compounds 1-1 to 1-6 and NiO from Device Example 1 x The brightness-current density relationship characteristic curve of the thermally evaporated perovskite blue light device in PVK (comparison sample). Detailed Implementation

[0109] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0110] In summary, the bifunctional phosphonic acid self-assembled molecule of the present invention has an intermediate having a general structure as shown in Formula A, and the self-assembled molecule has a general structure as shown in one of general formulas A-1 to A-4 (the R1 and R2 groups in any general formula can be the same group):

[0111]

[0112] Among them, R1 and R2 groups contain lone pairs of electrons, and can be independently selected from benzaldehyde, methyl sulfone, and benzoxy;

[0113] Specifically, the structural formula of the bifunctionalized phosphonic acid self-assembled molecule in this invention is as follows:

[0114]

[0115]

[0116] Accordingly, the bifunctional phosphonic acid self-assembled molecules are prepared from precursors. Specifically, general formula A-1 is prepared from precursor B-1 (i.e., 3,6-dibromocarbazole); A-2, A-3 and A-4 are prepared from B-2 (i.e., 3,7-dibromophenazine derivative), and the element X is O, S or Se; precursors B-1 and B-2 used in the following examples are commercially available.

[0117]

[0118] Specific preparation methods may include the following steps:

[0119] (1) Using 3,6-dibromocarbazole (3,7-dibromophenazine derivative in some synthetic examples) as a raw material, and combined with dibromoethane as a raw material, a nucleophilic substitution reaction was carried out to obtain 3,6-dibromo-bromoethyl-carbazole (3,7-dibromo-bromoethyl-phenazine in some synthetic examples);

[0120] (2) Using the 3,6-dibromo-bromoethyl-carbazole (3,7-dibromo-bromoethyl-phenazine) obtained in step (1) as a raw material, and reacting it with the raw material triethyl phosphonate to undergo an Arbuzov reaction, thereby obtaining a diethyl phosphonate-carbazole derivative (phenazine derivative in some synthetic examples).

[0121] (3) The diethyl phosphonate-carbazole derivative obtained in step (2) (in some synthetic examples, it is a phenazine derivative) is subjected to a Suzuki reaction using a borate ester derivative with a passivation group R1 to obtain a diethyl phosphonate-carbazole derivative with a functionalized group (in some synthetic examples, it is a phenazine derivative); the R1 group is benzaldehyde, methyl sulfone, or benzoxyl.

[0122] (4) The diethyl phosphonate carbazole derivative with functionalized groups obtained in step (3) is subjected to a Suzuki reaction using a borate ester derivative with a passivating group R2, thereby obtaining a diethyl phosphonate carbazole derivative with two functionalized groups (a phenazine derivative in some synthetic examples). The R2 group is benzaldehyde, methyl sulfone, or benzoxyl.

[0123] (5) The phosphonate diethyl carbazole derivative (a phenazine derivative in some synthetic examples) with two functional groups obtained in step (4) is combined with bromotrimethylsilane and hydrolyzed to obtain a bifunctional phosphonate carbazole self-assembled molecule (a bifunctional phosphonate phenazine self-assembled molecule in some synthetic examples).

[0124]

[0125] In some synthetic embodiments, the specific process involved in step (1) can be carried out in a solvent system with the participation of tetrabutylammonium bromide and a base. Specifically, 3,6-dibromocarbazole (3,7-dibromophenazine derivative in some synthetic embodiments), dibromoethane, tetrabutylammonium bromide, base (e.g., potassium hydroxide) and solvent (e.g., deionized water) are added to the reaction apparatus in a volume ratio of 1 mmol:1-2 mmol:0.1-0.3 mmol:3-5 mmol:5-10 ml. Then, the air is purged with nitrogen, and the mixture is heated to reflux under nitrogen protection for 24-48 hours. After the reaction is complete, it is cooled to room temperature for purification and post-treatment to obtain the compound in step (1).

[0126] In some synthetic examples, the specific process involved in step (2) can be triethyl phosphonate and alkyl halides in a solvent system. Specifically, 3,6-dibromo-bromoethyl-carbazole (3,7-dibromo-bromoethyl-phenazine in some synthetic examples) and 1 mmol: 1-1.5 mmol of triethyl phosphonate are added to the reaction apparatus, the air is purged with nitrogen, and then the mixture is heated to reflux under nitrogen protection for 24-48 hours. After the reaction is complete, it is cooled to room temperature for purification and post-processing to obtain carbazole and phenazine intermediate 4 of diethyl phosphonate; thus obtaining the compound in step (2).

[0127] In some synthetic embodiments, the specific processes involved in steps (3) and (4) can be as follows: the intermediate and boric acid raw material in step (2), the palladium catalyst is selected as tetrakis(triphenylphosphine)palladium, the base is selected as potassium carbonate, and the solvent is selected as ethanol and water. The intermediate, boric acid raw material, tetrakis(triphenylphosphine)palladium, potassium carbonate, ethanol and water are added to the reaction apparatus in a molar or volume ratio (ethanol and water) of 1 mmol: 1 mmol: 0.02-0.05 mmol: 2 mmol: 1 ml: 1 ml: 2 ml (wherein, the intermediate, boric acid raw material, tetrakis(triphenylphosphine)palladium, potassium carbonate, ethanol and water used in step (3) can also be in a molar or volume ratio (ethanol and water) of 1 mmol: 1 mmol: 0.02-0.05 mmol: 2 mmol: 1 ml: 1 ml: 2 ml. 0.5-1mmol:0.02-0.05mmol:2mmol:1ml:1ml:2ml, the intermediates, boric acid raw materials, tetra(triphenylphosphine)palladium, potassium carbonate, ethanol and water used in step (4) can also be in the molar or volume ratio (ethanol and water) of 1mmol:1-1.5mmol:0.02-0.05mmol:2mmol:1ml:1ml:2ml, the air is purged with nitrogen (e.g., for 15 minutes), and then heated to reflux under nitrogen protection for 12-48 hours (e.g., 12 hours). After the reaction is complete as detected by thin-layer chromatography, the mixture is cooled to room temperature for post-processing purification to obtain the compounds in steps (3) and (4).

[0128] In some synthetic examples, the specific process involved in step (5) can be as follows: the intermediate of step (4), bromotrimethylsilane, and dioxane are added to the reaction apparatus in a molar or volume ratio (dioxane) of 1 mmol: 1-2 mmol: 10 ml (e.g., 1 mmol: 1.5 mmol: 10 ml). The air is purged with nitrogen, and then the mixture is heated to reflux under nitrogen protection for 48-72 hours. After the reaction is complete, it is cooled to room temperature, 50 ml of deionized water is added, and the mixture is stirred for 2 hours. After filtration, the bifunctional phosphonate carbazole self-assembled molecules as shown in general formulas A-1 to A-4 are obtained (some synthetic examples are bifunctional phosphonate phenazine self-assembled molecules).

[0129] When R1 and R2 groups are the same, step (4) can be omitted. It is only necessary to increase the amount of borate ester derivative with passivation group R1 used in step (3) by at least 1 time, and at the same time increase the amount of palladium catalyst (the amount of other raw materials can remain unchanged, and the reaction conditions can remain unchanged). For example, when R1 and R2 groups are different, the molar ratio of diethyl phosphonate-carbazole derivative, borate ester derivative with passivation group R1, and tetra(triphenylphosphine)palladium in step (3) can be 1 mmol: 0.5-1 mmol: 0.02-0.05 mmol (step 4 can be set as 1 mmol: 1-1.5 mmol: 0.02-0.05 mmol); while when R1 and R2 groups are the same, the molar ratio of diethyl phosphonate-carbazole derivative, borate ester derivative with passivation group R1, and tetra(triphenylphosphine)palladium in step (3) can be 1 mmol: 2-2.5 mmol: 0.04-0.06 mmol.

[0130] In addition, similar to conventional processes in existing technologies, in the synthesis examples, the eluent for column chromatography is cyclohexane or a mixed solution of cyclohexane and dichloromethane in different volume ratios. Purification can specifically involve recrystallization; the preferred solvents for recrystallization are dichloromethane and toluene, while unsuitable solvents are methanol and cyclohexane.

[0131] The following are examples of synthesis:

[0132] Synthesis Example 1: The compound 1-1 of the present invention can be synthesized by the following method:

[0133]

[0134] (1) 3,6-Dibromocarbazole (4 g, 12.4 mmol), dibromoethane (70 ml, 3.13 mmol), tetrabutylammonium bromide (0.4 g, 1.24 mmol), potassium hydroxide (50 g, 0.89 mol), and deionized water (100 ml) were added to a 250 ml three-necked flask. Nitrogen gas was purged for 15 minutes, and then the mixture was heated to 60 °C under nitrogen atmosphere and stirred for 24 hours. After the reaction was complete, the mixture was cooled to room temperature. The organic layer was collected by washing with dichloromethane and water, dried, concentrated, and preliminarily purified by column chromatography. The crude product was further recrystallized from dichloromethane and methanol to obtain a white solid powder compound 1 (i.e., 3,6-dibromo-bromoethyl-carbazole), 5.1 g, yield 92.5%.

[0135] (2) Compound 1 (5g, 11.7mmol) and triethyl phosphonate (40ml) were added to a 100ml three-necked flask, purged with nitrogen for 15 minutes, and then heated to 165℃ under nitrogen and stirred for 20 hours. After the reaction was complete, the mixture was cooled to room temperature, and the organic layer was collected by washing with dichloromethane and water. After drying, the mixture was concentrated and preliminarily purified by column chromatography. The crude product was further recrystallized from dichloromethane and methanol to obtain compound 2, 5.4g, a white solid powder with a yield of 94.7%.

[0136] (3) Then, compound 2 (2g, 4.11mmol), 4-formylphenylboronic acid (3g, 2mmol), tetrakis(triphenylphosphine)palladium (0.05g, 0.04mmol), ethanol (4ml), deionized water (4ml), and dried toluene (8ml) were added to a 100ml three-necked flask. Nitrogen was purged for 15 minutes, and then the mixture was heated to 110°C and stirred under nitrogen for 12 hours. After the reaction was complete, the mixture was cooled to room temperature. The organic layer was collected by washing with dichloromethane and water, dried, concentrated, and preliminarily purified by column chromatography. The crude product was further recrystallized from dichloromethane and methanol to obtain compound 3, 2.2g, a white solid powder with a yield of 91.4%.

[0137] (4) Then, compound 3 (2g, 3.71mmol), dioxane (37ml), and trimethylbromosilane (6g, 3.91mmol) were added to a 50ml three-necked flask. Nitrogen gas was purged for 15 minutes, and the mixture was then refluxed and stirred at room temperature in a nitrogen atmosphere for 48 hours. After the reaction was complete, 20ml of deionized water was added and the mixture was stirred for 2 hours. After standing, the solid was collected and further dried to obtain a white solid powder compound 1-1, 1.4g, with a yield of 77.8%.

[0138] Compound 1-1: APCI-MS (m / z): Theoretical molecular weight: 483.12; Measured value: 484.13. Elemental analysis results: Theoretical values: C: 69.56%; H: 4.59%; N: 2.90%; O: 16.55%; P: 6.41%. Measured values: C: 69.61%; H: 4.56%; N: 2.92%; O: 16.52%; P: 6.39%. 1 ¹H NMR (500MHz, Chloroform) δ 9.94 (s, 2H), 8.15–7.95 (m, 7H), 7.88 (d, J = 4.7Hz, 2H), 7.86–7.75 (m, 4H), 7.65 (s, 1H), 4.35 (d, J = 14.9Hz, 4H), 2.20 (s, 1H). Based on the above test results, the product structure is correct and is the target compound 1-1.

[0139] Similarly, compounds 1-2 to 1-6 are basically the same as those in Example 1, except that the compounds selected for R1 and R2 are different, and are one of three molecules: 4-formylphenylboronic acid, 4-boronbenzenesulfonic acid, and 4-methoxyphenylboronic acid.

[0140] The characterization results of the obtained compounds are as follows:

[0141] Compounds 1-2: APCI-MS (m / z): Theoretical molecular weight: 533.11; Measured value: 534.11. Elemental analysis results: Theoretical values: C: 63.03%; H: 4.53%; N: 2.63%; O: 17.99%; P: 5.81%; S: 6.01%. Measured values: C: 63.14%; H: 4.47%; N: 2.67%; O: 18.13%; P: 5.77%; S: 5.88%. 1 ¹H NMR (500MHz, Chloroform) δ 9.92 (s, 2H), 8.11 (s, 5H), 8.02–7.82 (m, 24H), 7.75 (dd, J = 46.1, 6.9Hz, 4H), 7.69 (s, 1H), 4.45 (s, 5H), 4.34 (s, 5H), 3.34 (s, 7H), 2.19 (s, 4H). Based on the above test results, the product structure is correct and corresponds to target compounds 1-2.

[0142] Compounds 1-3: APCI-MS (m / z): Theoretical molecular weight: 485.14; Measured value: 486.14. Elemental analysis results: Theoretical values: C: 69.27%; H: 4.98%; N: 2.89%; O: 16.48%; P: 6.38%. Measured values: C: 69.30%; H: 4.86%; N: 2.92%; O: 16.61%; P: 6.31%. 1 ¹H NMR (500MHz, Chloroform) δ 9.92 (s, 4H), 8.13 (dt, J = 12.2, 6.1Hz, 5H), 8.09 (s, 5H), 8.05–7.90 (m, 9H), 7.89–7.75 (m, 23H), 7.70 (s, 1H), 7.69 (s, 3H), 7.68–7.53 (m, 10H), 7.02–6.89 (m, 9H), 4.45 (s, 9H), 4.34 (s, 9H), 3.88 (s, 13H), 2.19 (s, 7H). Based on the above test results, the product structure is correct and corresponds to target compounds 1-3.

[0143] Compounds 1-4: APCI-MS (m / z): Theoretical molecular weight 583.09, measured value 584.10. Elemental analysis results: Theoretical values: C: 57.63%; H: 4.49%; N: 2.40%; O: 19.19%; P: 5.31%; S: 10.99%. Experimental values: C: 57.68%; H: 4.40%; N: 2.47%; O: 19.38%; P: 5.26%; S: 10.81%. 1 ¹H NMR (500MHz, Chloroform) δ 8.11 (s, ¹H), 8.02–7.93 (m, ¹⁰H), 7.91 (s, ¹H), 7.86 (s, ¹H), 7.63 (s, ¹H), 4.49 (s, ²H), 4.36 (s, ²H), 3.34 (s, ⁶H), 2.19 (s, ¹H). The above test results indicate that the product structure is correct and corresponds to target compounds 1-4.

[0144] Compounds 1-5: APCI-MS (m / z): Theoretical molecular weight: 535.12; Measured value: 536.12. Elemental analysis results: Theoretical values: C: 62.80%; H: 4.89%; N: 2.62%; O: 17.92%; P: 5.78%; S: 5.99%. Measured values: C: 62.82%; H: 4.85%; N: 2.68%; O: 18.06%; P: 5.72%; S: 5.87%. 1 ¹H NMR (500MHz, Chloroform) δ 8.12 (d, J = 3.6Hz, 2H), 7.94 (dt, J = 38.8, 19.4Hz, 5H), 7.84 (s, 1H), 7.74 (d, J = 39.1Hz, 2H), 7.68–7.53 (m, 2H), 7.02–6.88 (m, 2H), 4.44 (s, 2H), 4.34 (s, 2H), 3.88 (s, 3H), 3.34 (s, 3H), 2.19 (s, 1H). Based on the above test results, the product structure is correct and corresponds to target compounds 1-5.

[0145] Compounds 1-6: APCI-MS (m / z): Theoretical molecular weight: 487.15; Measured value: 488.15. Elemental analysis results: Theoretical values: C: 68.99%; H: 5.38%; N: 2.87%; O: 16.41%; P: 6.35%. Measured values: C: 69.03%; H: 5.32%; N: 2.93%; O: 16.49%; P: 6.23%. 1¹H NMR (500MHz, Chloroform) δ 8.08 (s, 1H), 7.98–7.94 (m, 2H), 7.86 (d, J = 19.7Hz, 2H), 7.63–7.57 (m, 5H), 7.02–6.89 (m, 4H), 4.32 (s, 2H), 4.13 (s, 2H), 3.88 (s, 6H), 2.16 (s, 1H). The above test results indicate that the product structure is correct and corresponds to the target compounds 1-6.

[0146] Similarly, the self-assembled molecules of compounds 2-1 to 2-6 are similar to those synthesized in the examples of compounds 1-2 to 1-6. The difference is that the 3,6-dibromocarbazole raw material used in step (1) is replaced with 3,7-dibromo-10H-phenoxazine.

[0147] The characterization results of the obtained compounds are as follows:

[0148] Compound 2-1: APCI-MS (m / z): Theoretical molecular weight: 499.12; Measured value: 500.13. Elemental analysis results: Theoretical values: C: 67.33%; H: 4.44%; N: 2.80%; O: 19.22%; P: 6.20%. Measured values: C: 67.40%; H: 4.39%; N: 2.87%; O: 19.31%; P: 6.03%. 1 ¹H NMR (500MHz, Chloroform) δ 9.91 (s, ¹H), 8.04–7.90 (m, ³H), 7.90–7.76 (m, ³H), 7.62–7.58 (m, ¹H), 7.45–7.31 (m, ¹H), 7.31–7.16 (m, ¹H), 5.05 (s, ¹H), 4.46 (s, ¹H), 2.13 (s, ¹H). Based on the above test results, the product structure is correct and is the target compound 2-1.

[0149] Compound 2-2: High-resolution mass spectrometry (APCI-MS) (m / z): Theoretical molecular weight: 549.10; Measured value: 550.10. Elemental analysis results: Theoretical values: C: 61.20%; H: 4.40%; N: 2.55%; O: 20.38%; P: 5.64%; S: 5.83%. Measured values: C: 61.24%; H: 4.36%; N: 2.59%; O: 20.43%; P: 5.58%; S: 5.80%. 1¹H NMR (500MHz, Chloroform) δ 9.94 (s, 1H), 8.05–7.87 (m, 6H), 7.87–7.74 (m, 2H), 7.55 (d, J = 2.6Hz, 2H), 7.36 (d, J = 0.6Hz, 2H), 7.33–7.17 (m, 2H), 4.98 (s, 2H), 4.36 (s, 2H), 3.33 (s, 3H), 2.13 (s, 1H). Based on the above test results, the product structure is correct and is the target compound 2-2.

[0150] Compounds 2-3: APCI-MS (m / z): Theoretical molecular weight: 501.13; Measured value: 502.14. Elemental analysis results: Theoretical values: C: 67.06%; H: 4.82%; N: 2.79%; O: 19.14%; P: 6.18%. Measured values: C: 67.11%; H: 4.78%; N: 2.83%; O: 19.18%; P: 6.10%. 1 ¹H NMR (500MHz, Chloroform) δ 9.93 (s, 1H), 8.05–7.91 (m, 2H), 7.88–7.74 (m, 2H), 7.56 (dd, J = 14.0, 7.1Hz, 4H), 7.35 (d, J = 6.2Hz, 2H), 7.24 (d, J = 5.1Hz, 2H), 7.02–6.88 (m, 2H), 4.94 (s, 2H), 4.41 (s, 2H), 3.87 (s, 3H), 2.11 (s, 1H). Based on the above test results, the product structure is correct and is the target compound 2-3.

[0151] Compounds 2-4: APCI-MS (m / z): Theoretical molecular weight: 599.08; Measured value: 600.08. Elemental analysis results: Theoretical values: C: 56.09%; H: 4.37%; N: 2.34%; O: 21.35%; P: 5.17%; S: 10.69%. Measured values: C: 56.14%; H: 4.32%; N: 2.38%; O: 21.39%; P: 5.13%; S: 10.64%. 1 ¹H NMR (500MHz, Chloroform) δ 8.01–7.87 (m, 5H), 7.57–7.53 (m, 1H), 7.42–7.28 (m, 1H), 7.28–7.17 (m, 1H), 4.97 (s, 1H), 4.36 (s, 1H), 3.33 (s, 4H), 2.13 (s, 1H). Based on the above test results, the product structure is correct and corresponds to the target compound 2-4.

[0152] Compounds 2-5: APCI-MS (m / z): Theoretical molecular weight: 551.12; Measured value: 552.13. Elemental analysis results: Theoretical values: C: 60.98%; H: 4.75%; N: 2.54%; O: 20.31%; P: 5.62%; S: 5.81%. Measured values: C: 61.03%; H: 4.71%; N: 2.59%; O: 20.35%; P: 5.60%; S: 5.72%. 1 ¹H NMR (500MHz, Chloroform) δ 8.01–7.87 (m, 3H), 7.56 (dd, J = 14.6, 6.6Hz, 3H), 7.35 (d, J = 4.5Hz, 1H), 7.24 (d, J = 3.5Hz, 1H), 7.02–6.88 (m, 1H), 4.97 (s, 1H), 4.35 (s, 1H), 3.87 (s, 2H), 3.33 (s, 2H), 2.13 (s, 1H). Based on the above test results, the product structure is correct and is the target compound 2-5.

[0153] Compounds 2-6: APCI-MS (m / z): Theoretical molecular weight: 503.15; Measured value: 504.16. Elemental analysis results: Theoretical values: C: 66.80%; H: 5.21%; N: 2.78%; O: 19.07%; P: 6.15%. Measured values: C: 66.83%; H: 5.17%; N: 2.80%; O: 19.11%; P: 6.09%. 1 ¹H NMR (500MHz, Chloroform) δ 7.65–7.55 (m, 3H), 7.55–7.51 (m, 1H), 7.41–7.32 (m, 1H), 7.32–7.16 (m, 1H), 7.02–6.88 (m, 3H), 4.97 (s, 1H), 4.35 (s, 1H), 3.87 (s, 4H), 2.13 (s, 1H). Based on the above test results, the product structure is correct and corresponds to the target compound 2-6.

[0154] Similarly, the self-assembled molecules of compounds 3-1 to 3-6 are similar to those synthesized in the examples of compounds 1-2 to 1-6. The difference is that the 3,6-dibromocarbazole raw material used in step (1) is replaced with 3,7-dibromo-10H-phenthiazide.

[0155] The characterization results of the obtained compounds are as follows:

[0156] Compound 3-1: APCI-MS (m / z): Theoretical molecular weight: 515.52; Measured value: 516.52. Elemental analysis results: Theoretical values: C: 65.24%; H: 4.30%; N: 2.72%; O: 15.52%; P: 6.01%; S: 6.22%. Measured values: C: 66.27%; H: 4.26%; N: 2.73%; O: 15.56%; P: 5.98%; S: 6.20%. 1 ¹H NMR (500MHz, Chloroform) δ 9.91 (s, ¹H), 8.03–7.89 (m, ³H), 7.89–7.76 (m, ³H), 7.69–7.65 (m, ¹H), 7.50–7.35 (m, ¹H), 7.35–7.19 (m, ¹H), 4.94 (s, ¹H), 4.35 (s, ¹H), 1.98 (s, ¹H). Based on the above test results, the product structure is correct and is the target compound 3-1.

[0157] Compound 3-2: High-resolution mass spectrometry (APCI-MS) (m / z): Theoretical molecular weight: 565.59; Measured value: 566.58. Elemental analysis results: Theoretical values: C: 59.46%; H: 4.28%; N: 2.48%; O: 16.97%; P: 5.48%; S: 11.34%. Measured values: C: 59.48%; H: 4.24%; N: 2.50%; O: 17.01%; P: 5.47%; S: 11.30%. 1 ¹H NMR (500MHz, Chloroform) δ 9.91 (s, 1H), 8.06–7.92 (m, 6H), 7.92–7.78 (m, 2H), 7.76 (s, 1H), 7.71 (s, 1H), 7.46 (d, J = 1.8Hz, 2H), 7.37–7.21 (m, 2H), 4.96 (s, 2H), 4.52 (s, 2H), 3.31 (s, 3H), 2.12 (s, 2H). Based on the above test results, the product structure is correct and is the target compound 3-2.

[0158] Compound 3-3: APCI-MS (m / z): Theoretical molecular weight: 517.54; Measured value: 518.53. Elemental analysis results: Theoretical values: C: 64.98%; H: 4.67%; N: 2.71%; O: 15.46%; P: 5.98%; S: 6.19%. Measured values: C: 65.01%; H: 4.66%; N: 2.74%; O: 15.48%; P: 5.95%; S: 6.16%. 1¹H NMR (500MHz, Chloroform) δ 9.91 (s, ¹H), 8.04–7.89 (m, 2H), 7.89–7.75 (m, 2H), 7.67 (s, ¹H), 7.65–7.52 (m, 3H), 7.41 (d, J = 12.8Hz, 2H), 7.27 (d, J = 10.1Hz, 2H), 7.02–6.88 (m, 2H), 4.93 (s, 2H), 4.34 (s, 2H), 3.87 (s, 3H), 1.98 (s, ¹H). Based on the above test results, the product structure is correct and is the target compound 3-3.

[0159] Compounds 3-4: APCI-MS (m / z): Theoretical molecular weight is 615.67, measured value: 616.67. Elemental analysis results: Theoretical values: C: 54.62%; H: 4.26%; N: 2.28%; O: 18.19%; P: 5.03%; S: 15.62%. Experimental values: C: 54.63%; H: 4.23%; N: 2.31%; O: 18.21%; P: 5.01%; S: 15.61%. 1 ¹H NMR (500MHz, Chloroform) δ 8.02–7.86 (m, 6H), 7.66–7.61 (m, 1H), 7.47–7.39 (m, 1H), 7.39–7.22 (m, 2H), 4.94 (s, 1H), 4.37 (s, 1H), 3.33 (s, 4H), 2.12 (s, 1H). Based on the above test results, the product structure is correct and corresponds to the target compound 3-4.

[0160] Compounds 3-5: APCI-MS (m / z): Theoretical molecular weight: 567.61; Measured value: 568.61. Elemental analysis results: Theoretical values: C: 59.25%; H: 4.62%; N: 2.47%; O: 16.91%; P: 5.46%; S: 11.30%. Measured values: C: 59.27%; H: 4.57%; N: 2.50%; O: 16.88%; P: 5.49%; S: 11.29%. 1¹H NMR (500MHz, Chloroform) δ 8.02–7.86 (m, 3H), 7.63 (d, J = 12.7Hz, 1H), 7.59–7.50 (m, 1H), 7.39 (d, J = 3.8Hz, 1H), 7.30 (d, J = 2.9Hz, 1H), 7.02–6.88 (m, 1H), 4.94 (s, 1H), 4.37 (s, 1H), 3.87 (s, 2H), 3.33 (s, 2H), 2.12 (s, 1H). Based on the above test results, the product structure is correct and corresponds to the target compound 3-5.

[0161] Compounds 3-6: APCI-MS (m / z): Theoretical molecular weight: 519.55; Measured value: 520.56. Elemental analysis results: Theoretical values: C: 64.73%; H: 5.04%; N: 2.70%; O: 15.40%; P: 5.96%; S: 6.17%. Measured values: C: 64.74%; H: 5.02%; N: 2.73%; O: 15.38%; P: 5.97%; S: 6.16%. 1 ¹H NMR (500MHz, Chloroform) δ 7.72–7.68 (m, 1H), 7.66–7.51 (m, 2H), 7.49–7.34 (m, 1H), 7.34–7.19 (m, 1H), 7.01–6.87 (m, 2H), 5.02 (s, 1H), 4.42 (s, 1H), 3.87 (s, 3H), 2.09 (s, 1H). Based on the above test results, the product structure is correct and corresponds to the target compound 3-6.

[0162] Similarly, the self-assembled molecules of compounds 4-1 to 4-6 are similar to those synthesized in the examples of compounds 1-2 to 1-6. The difference is that the 3,6-dibromocarbazole raw material used in step (1) is replaced with 3,7-dibromo-10H-phenselenazine.

[0163] Compound 4-1: APCI-MS (m / z): Theoretical molecular weight: 562.43; Measured value: 563.44. Elemental analysis results: Theoretical values: C: 59.80%; H: 3.94%; N: 2.49%; O: 14.22%; P: 5.51%; Se: 14.04%. Measured values: C: 59.83%; H: 3.92%; N: 2.51%; O: 14.18%; P: 5.52%; Se: 14.04%. 1¹H NMR (500MHz, Chloroform) δ 9.91 (s, ¹H), 8.02–7.88 (m, ³H), 7.88–7.76 (m, ³H), 7.73–7.69 (m, ¹H), 7.55–7.39 (m, ¹H), 7.39–7.22 (m, ¹H), 4.82 (s, ¹H), 4.23 (s, ¹H), 1.83 (s, ¹H). The above test results indicate that the product structure is correct and is the target compound 4-1.

[0164] Compound 4-2: APCI-MS (m / z): Theoretical molecular weight: 512.51; Measured value: 513.52. Elemental analysis results: Theoretical values: C: 54.91%; H: 3.95%; N: 2.29%; O: 15.67%; P: 5.06%; S: 5.23%; Se: 12.89%. Measured values: C: 54.94%; H: 3.93%; N: 2.31%; O: 15.66%; P: 5.09%; S: 5.21%; Se: 12.86%. 1 ¹H NMR (500MHz, Chloroform) δ 9.88 (s, 1H), 8.07–7.95 (m, 6H), 7.95–7.80 (m, 2H), 7.78 (s, 1H), 7.73 (s, 1H), 7.48 (d, J = 1.8Hz, 2H), 7.39–7.23 (m, 2H), 4.94 (s, 2H), 4.67 (s, 2H), 3.29 (s, 3H), 2.11 (s, 2H). The above test results indicate that the product structure is correct and is the target compound 4-2.

[0165] Compound 4-3: APCI-MS (m / z): Theoretical molecular weight: 564.45; Measured value: 565.44. Elemental analysis results: Theoretical values: C: 59.58%; H: 4.29%; N: 2.48%; O: 14.17%; P: 5.49%; Se: 13.99%. Measured values: C: 59.60%; H: 4.28%; N: 2.52%; O: 14.14%; P: 5.51%; Se: 13.95%. 1¹H NMR (500MHz, Chloroform) δ 9.88 (s, ¹H), 8.03–7.87 (m, 2H), 7.87–7.73 (m, 2H), 7.65 (s, ¹H), 7.63–7.50 (m, 3H), 7.39 (d, J = 12.8Hz, 2H), 7.25 (d, J = 10.1Hz, 2H), 7.00–6.86 (m, 2H), 4.92 (s, 2H), 4.27 (s, 2H), 3.87 (s, 3H), 1.86 (s, ¹H). Based on the above test results, the product structure is correct and is the target compound 4-3.

[0166] Compound 4-4: APCI-MS (m / z): Theoretical molecular weight: 662.58; Measured value: 663.58. Elemental analysis results: Theoretical values: C: 50.76%; H: 3.96%; N: 2.11%; O: 16.90%; P: 4.67%; S: 9.68%; Se: 11.92%. Measured values: C: 50.78%; H: 3.92%; N: 2.13%; O: 16.88%; P: 4.69%; S: 9.67%; Se: 11.93%. 1 ¹H NMR (500MHz, Chloroform) δ 8.03–7.85 (m, 6H), 7.75–7.70 (m, 1H), 7.52–7.45 (m, 1H), 7.45–7.25 (m, 2H), 4.91 (s, 1H), 4.38 (s, 1H), 3.33 (s, 4H), 2.11 (s, 1H). Based on the above test results, the product structure is correct and is the target compound 4-4.

[0167] Compounds 4-5: APCI-MS (m / z): Theoretical molecular weight: 614.52; Measured value: 615.51. Elemental analysis results: Theoretical values: C: 54.73%; H: 4.26%; N: 2.28%; O: 15.62%; P: 5.04%; S: 5.22%; Se: 12.85%. Measured values: C: 54.75%; H: 4.23%; N: 2.30%; O: 15.61%; P: 5.06%; S: 5.19%; Se: 12.86%. 1¹H NMR (500MHz, Chloroform) δ 8.03–7.85 (m, 3H), 7.70 (d, J = 12.7Hz, 1H), 7.66–7.57 (m, 1H), 7.46 (d, J = 3.8Hz, 1H), 7.37 (d, J = 2.9Hz, 1H), 7.05–6.91 (m, 1H), 4.91 (s, 1H), 4.39 (s, 1H), 3.87 (s, 2H), 3.33 (s, 2H), 2.11 (s, 1H). Based on the above test results, the product structure is correct and corresponds to the target compound 4-5.

[0168] Compounds 4-6: APCI-MS (m / z): Theoretical molecular weight: 566.46; Measured value: 567.45. Elemental analysis results: Theoretical values: C: 59.37%; H: 4.63%; N: 2.47%; O: 14.12%; P: 5.47%; Se: 13.94%. Measured values: C: 59.39%; H: 4.60%; N: 2.49%; O: 14.08%; P: 5.49%; Se: 13.95%. 1 ¹H NMR (500MHz, Chloroform) δ 7.79–7.75 (m, 1H), 7.69–7.51 (m, 2H), 7.53–7.38 (m, 1H), 7.38–7.23 (m, 1H), 7.00–6.86 (m, 2H), 5.07 (s, 1H), 4.49 (s, 1H), 3.87 (s, 3H), 2.05 (s, 1H). Based on the above test results, the product structure is correct and corresponds to the target compound 4-6.

[0169] The aforementioned bifunctionalized self-assembled molecules can be used as a multifunctional layer at the buried interface of PeLEDs. (See attached image) Figure 1 A schematic diagram of an electroluminescent device structure is provided as an example. (Attached) Figure 2 To illustrate the mechanism of action of the bifunctional self-assembled molecules in this invention as a multifunctional layer at the buried interface in an electroluminescent device, the bifunctional self-assembled molecules can form strong chemical bonds with metal oxide substrates (such as ITO), and also with uncoordinated Pb in perovskites. 2+ They are interconnected through electrostatic interactions. The SAM layer is the bifunctional self-assembled molecule described in this invention.

[0170] The bifunctional self-assembled molecules described in this invention are used in PeLEDs. Specific preparation processes may include, for example: (1) Substrate pretreatment: ITO glass substrates are ultrasonically cleaned for 30 minutes in ITO cleaning agent, isopropanol, acetone, ethanol, and deionized water, dried with nitrogen, and then dried in an oven at 120°C for 2 hours. Before device fabrication, the ITO glass substrates are surface-treated with oxygen plasma for 5 minutes. (2) SAM layer spin coating: The bifunctional self-assembled molecules are prepared into a solution (solvent is dimethyl sulfoxide, concentration is 1 mg / ml), and spin-coated at 4000 r / min for 30 s. Annealing at 90°C for 10 min (on the one hand, this removes the solvent; on the other hand, it ensures the integrity of the chemical bonds between the multifunctional layer and the metal oxide surface layer, avoiding pores in the multifunctional layer). Unanchored bifunctional self-assembled molecules on the surface are cleaned with ethanol to form a multifunctional layer with a single-molecule thickness (thickness approximately 1-2 nm). (3) Thermal evaporation of each functional layer of the device. The film thickness of each functional layer is systematically optimized.

[0171] The device structure used in this invention is: ITO / multifunctional layer / perovskite light-emitting layer / electron transport layer / LiF / Al, wherein:

[0172] The multifunctional layer uses the aforementioned bifunctional self-assembled molecule.

[0173] The perovskite emitting layer is a thermally evaporated perovskite, including but not limited to blue or green perovskite emitting layers prepared by dual-source co-evaporation or ternary co-evaporation. The perovskite precursor materials used include, but are not limited to, CsBr, CsCl, PbCl2, and PEACl. Furthermore, the precursor used should satisfy the requirement of an A-site cation (such as CsBr). + ): B-site cation (i.e., Pb) 2+ Halogen ions (such as Br₂) - Cl - The ratio of light to halogen ions (Br) is 1-4:1:3-6. Different light colors can be achieved by adjusting the ratio of halogen ions (Br). - and Cl - The proportion is achieved by increasing Br. - The concentration of [Cl] causes the device to emit a green light, and increasing the Cl content [results in a green light]. - The content of the light will cause the device to emit more blue light.

[0174] The electron transport layer selected is TPBi, TmPyPB, and C. 60 wait.

[0175] The device structures used in the device embodiments described below can be categorized as follows:

[0176] Structure 1: ITO / multifunctional layer / blue light perovskite (100nm) / TPBi (20nm) / LiF (1nm) / Al (100nm).

[0177] Structure 2: ITO / multifunctional layer / blue light perovskite (100nm) / TmPyPB (30nm) / LiF (1nm) / Al (100nm).

[0178] Structure 3: ITO / Multifunctional layer / Blue light perovskite (100nm) / C 60 (15nm) / LiF(1nm) / Al(100nm).

[0179] Structure 4: ITO / multifunctional layer / green perovskite (50nm) / TPBi (20nm) / LiF (1nm) / Al (100nm).

[0180] Structure 5: ITO / multifunctional layer / green perovskite (30nm) / TmPyPB (40nm) / LiF (1nm) / Al (100nm).

[0181] Structure 6: ITO / Multifunctional layer / Green perovskite (60nm) / C 60 (15nm) / LiF(1nm) / Al(100nm).

[0182] Among them, the Br used in the Blue Light Perovskite - Cl - The molar ratio is 3:1; the Br used in the green light perovskite... - Cl - The molar ratio is 1:3. Additionally, the conventional hole transport layer used in the comparative samples of device examples 1-5 is NiO. x / PVK, where NiO x Purchased from Liaoning Youxuan New Energy Technology Co., Ltd.; PVK purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; NiO x The thicknesses of PVK and PVK are 10 nm and 20 nm, respectively. In Device Example 6, the conventional hole transport layer used in Comparative Sample 1 and Comparative Sample 2 is 2PACz or 2PACz / TPPO; 2PACz and TPPO were purchased from Xi'an Baolai Optoelectronic Technology Co., Ltd. 2PACz is a phosphonic acid self-assembled molecule without passivation groups and is used only as a hole transport material, existing in the device as a monolayer; TPPO is used as a passivation layer between the light-emitting layer and 2PACz, with a thickness of 5 nm.

[0183] The following are examples of the device:

[0184] Device Example 1:

[0185] The device structure used in this embodiment is structure 1. The multifunctional layer is one of the bifunctional self-assembled molecules 1-1 to 1-6, 2-1, 3-1 or 4-1 described in this invention.

[0186] When the multifunctional layer material is 1-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The luminance is 10.41%, and the highest brightness can reach 1843 cd / m². 2 .

[0187] When the multifunctional layer material is 1-2, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.33%, and the highest brightness can reach 1376 cd / m². 2 .

[0188] When the multifunctional layer material is 1-3, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.12%, and the highest brightness can reach 1421 cd / m². 2 .

[0189] When the multifunctional layer material is 1-4, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.10%, and the highest brightness can reach 1102 cd / m². 2 .

[0190] When the multifunctional layer material is 1-5, the peak wavelength of electroluminescence is 488nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.02%, and the highest brightness can reach 1221 cd / m². 2 .

[0191] When the multifunctional layer material is 1-6, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing information]. max The brightness is 7.81%, and the highest brightness can reach 1336 cd / m². 2 .

[0192] When the multifunctional layer material is 2-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.75%, and the highest brightness can reach 1820 cd / m². 2 .

[0193] When the multifunctional layer material is 3-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 10.03%, and the highest brightness can reach 1958 cd / m². 2 .

[0194] When the multifunctional layer material is 4-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 10.22%, and the highest brightness can reach 1989 cd / m².2 .

[0195] The comparison device replaces the multifunctional layer material with a traditional hole transport layer structure, NiO. x / PVK, the device has an electroluminescence peak wavelength of 488nm and a maximum external quantum efficiency (EQE). max The brightness is 4.68%, and the highest brightness can reach 575 cd / m². 2 .

[0196] Device Example 2:

[0197] The device structure used in this embodiment is structure 2. The multifunctional layer is one of the bifunctional self-assembled molecules 2-1 to 2-6, 3-1 or 4-1 described in this invention.

[0198] When the multifunctional layer material is 2-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.63%, and the highest brightness can reach 1320 cd / m². 2 .

[0199] When the multifunctional layer material is 2-2, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.59%, and the highest brightness can reach 1090 cd / m². 2 .

[0200] When the multifunctional layer material is 2-3, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.82%, and the highest brightness can reach 903 cd / m². 2 .

[0201] When the multifunctional layer material is 2-4, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.06%, and the highest brightness can reach 840 cd / m². 2 .

[0202] When the multifunctional layer material is 2-5, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 7.70%, and the highest brightness can reach 637 cd / m². 2 .

[0203] When the multifunctional layer material is 2-6, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 7.51%, and the highest brightness can reach 788 cd / m². 2 .

[0204] When the multifunctional layer material is 3-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.81%, and the highest brightness can reach 1304 cd / m². 2 .

[0205] When the multifunctional layer material is 4-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.97%, and the highest brightness can reach 1322 cd / m². 2 .

[0206] The comparison device replaces the multifunctional layer material with a traditional hole transport layer structure, NiO. x / PVK, the device has an electroluminescence peak wavelength of 488nm and a maximum external quantum efficiency (EQE). max The brightness is 4.33%, and the highest brightness can reach 633 cd / m². 2 .

[0207] Device Example 3:

[0208] The device structure used in this embodiment is structure 3. The multifunctional layer is one of the bifunctional self-assembled molecules 3-1 to 3-6, 1-1, 2-1 or 4-1 described in this invention.

[0209] When the multifunctional layer material is 3-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.96%, and the highest brightness can reach 1128 cd / m². 2 .

[0210] When the multifunctional layer material is 3-2, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.50%, and the highest brightness can reach 1076 cd / m². 2 .

[0211] When the multifunctional layer material is 3-3, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.33%, and the highest brightness can reach 1027 cd / m². 2 .

[0212] When the multifunctional layer material is 3-4, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 7.93%, and the highest brightness can reach 1040 cd / m². 2 .

[0213] When the multifunctional layer material is 3-5, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value].max The brightness is 7.71%, and the highest brightness can reach 986 cd / m². 2 .

[0214] When the multifunctional layer material is 3-6, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 7.52%, and the highest brightness can reach 960 cd / m². 2 .

[0215] When the multifunctional layer material is 1-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.64%, and the highest brightness can reach 1439 cd / m². 2 .

[0216] When the multifunctional layer material is 2-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 9.25%, and the highest brightness can reach 1287 cd / m². 2 .

[0217] When the multifunctional layer material is 4-1, the peak wavelength of electroluminescence is 488 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 8.42%, and the highest brightness can reach 1022 cd / m². 2 .

[0218] The comparison device replaces the multifunctional layer material with a traditional hole transport layer structure, NiO. x / PVK, the device has an electroluminescence peak wavelength of 488nm and a maximum external quantum efficiency (EQE). max The brightness is 4.22%, and the highest brightness can reach 610 cd / m². 2 .

[0219] Device Example 4:

[0220] The device structure used in this embodiment is structure 4. The multifunctional layer is one of the bifunctional self-assembled molecules 4-1 to 4-6, 1-1, 2-1 or 3-1 described in this invention.

[0221] When the multifunctional layer material is 4-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 14.32%, and the highest brightness can reach 9022 cd / m². 2 .

[0222] When the multifunctional layer material is 4-2, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 13.66%, and the highest brightness can reach 8790 cd / m². 2 .

[0223] When the multifunctional layer material is 4-3, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 13.05%, and the highest brightness can reach 8691 cd / m². 2 .

[0224] When the multifunctional layer material is 4-4, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The luminance is 13.41%, and the highest brightness can reach 8720 cd / m². 2 .

[0225] When the multifunctional layer material is 4-5, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 11.83%, and the highest brightness can reach 8545 cd / m². 2 .

[0226] When the multifunctional layer material is 4-6, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 10.38%, and the highest brightness can reach 8343 cd / m². 2 .

[0227] When the multifunctional layer material is 1-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 20.34%, and the highest brightness can reach 13022 cd / m². 2 .

[0228] When the multifunctional layer material is 2-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 18.32%, and the highest brightness can reach 11462 cd / m². 2 .

[0229] When the multifunctional layer material is 3-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing information]. max The brightness is 16.17%, with a maximum brightness of 9822 cd / m². 2 .

[0230] The comparison device replaces the multifunctional layer material with a traditional hole transport layer structure, NiO. x / PVK, the device has an electroluminescence peak wavelength of 512nm and a maximum external quantum efficiency (EQE). max The brightness was 6.72%, with a maximum brightness of only 3688 cd / m². 2 .

[0231] Device Example 5: The device structure used in this example is structure 5. The multifunctional layer is one of the bifunctional self-assembled molecules 1-1, 2-1, 3-1, or 4-1 described in this invention.

[0232] When the multifunctional layer material is 1-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 19.20%, and the highest brightness can reach 7322 cd / m². 2 .

[0233] When the multifunctional layer material is 2-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 17.34%, and the highest brightness can reach 7046 cd / m². 2 .

[0234] When the multifunctional layer material is 3-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing information]. max The brightness is 15.63%, and the highest brightness can reach 6630 cd / m². 2 .

[0235] When the multifunctional layer material is 4-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 15.10%, with a maximum brightness of 5709 cd / m². 2 .

[0236] The comparison device replaces the multifunctional layer material with a traditional hole transport layer structure, NiO. x / PVK, the device has an electroluminescence peak wavelength of 512nm and a maximum external quantum efficiency (EQE). max The brightness was 7.02%, with a maximum brightness of only 1475 cd / m². 2 .

[0237] Device Example 6: The device structure used in this example is structure 6. The multifunctional layer is one of the bifunctional self-assembled molecules 1-1, 2-1, 3-1, or 4-1 described in this invention.

[0238] When the multifunctional layer material is 1-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 18.74%, and the highest brightness can reach 7636 cd / m². 2 .

[0239] When the multifunctional layer material is 2-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 15.65%, and the highest brightness can reach 7157 cd / m². 2 .

[0240] When the multifunctional layer material is 3-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing information]. max The brightness is 13.92%, and the highest brightness can reach 6637 cd / m². 2 .

[0241] When the multifunctional layer material is 4-1, the peak wavelength of electroluminescence is 512 nm, and the maximum external quantum efficiency (EQE) is [missing value]. max The brightness is 12.28%, and the highest brightness can reach 5996 cd / m². 2 .

[0242] Comparative device 1 uses 2PACz as the hole transport layer and does not use any passivation layer; the results are as follows: the electroluminescence peak wavelength is 512nm, and the maximum external quantum efficiency (EQE) is... max The brightness was 4.60%, with a maximum brightness of only 1036 cd / m². 2 .

[0243] Comparative device 2 uses 2PACz as the hole transport layer and TPPO as the passivation layer; the results are as follows: the electroluminescence peak wavelength is 512nm, and the maximum external quantum efficiency (EQE) is [missing information]. max The luminance was 10.88%, and the highest brightness was only 3036 cd / m². 2 .

[0244] The above embodiments demonstrate that the bifunctional self-assembled molecules based on the present invention can effectively improve the external quantum efficiency of thermally evaporated PeLEDs. This is mainly due to the fact that SAMs, as a multifunctional layer, are connected by covalent bonds on both sides, which on the one hand constructs a stable and efficient carrier transport channel, and on the other hand effectively passivates defects at the perovskite buried interface. At the same time, since the bifunctional layer replaces the traditional hole transport layer and passivation additives, the spacing thickness between the light-emitting layer and the substrate is reduced, and the loss during the light extraction process is reduced, thus greatly improving the brightness of the light-emitting device.

[0245] Appendix Figure 4 The external quantum efficiency-current density relationship curves are shown for bifunctional self-assembled molecules 1-1 to 1-6 as multifunctional layers. From the external quantum efficiency curves of thermally evaporated PeLEDs, it can be clearly concluded that the device's luminous efficiency is at a high level, and from the attached... Figure 5 As can be seen from the brightness-current density relationship curve, the brightness improvement is also significant when using the SAMs molecules described in this invention as a multifunctional layer. This meets the requirements for the industrial application of PeLEDs.

[0246] The above embodiments are merely examples. Taking the device embodiment as an example, in addition to the six structures with specific layer compositions and layer thicknesses mentioned above, the present invention is also applicable to perovskite light-emitting diode devices with other layer compositions and other thicknesses, as long as the multifunctional layer uses the bifunctional phosphonic acid self-assembled molecules of the present invention. The thickness can be in addition to the thickness of a single molecule, or it can be a multilayer molecule (for example, the cathode, electron injection layer, electron transport layer, and light-emitting layer can also use other materials reported in the prior art); in addition, the anode can be other metal oxide electrodes (such as FTO, etc.) in addition to ITO.

[0247] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements 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 phosphonic acid self-assembled molecule for use in perovskite light-emitting diodes, possessing both hole transport and perovskite passivation effects, characterized in that, This self-assembled molecule has a structure as shown in one of general formulas A-1 to A-4: The R1 and R2 groups are independently selected from: benzaldehyde group and methyl sulfone group.

2. The method for preparing a phosphonic acid self-assembled molecule for perovskite light-emitting diodes, as described in claim 1, and possessing both hole transport and perovskite passivation effects, is characterized in that... When the self-assembled molecule has a structure as shown in one of general formulas A-2 to A-4, and R1 and R2 are the same, the preparation method includes the following steps: (1) Using the 3,7-dibromophenazine derivative shown in Formula 1 as a raw material, and combined with the dibromoethane shown in Formula 2, a nucleophilic substitution reaction is carried out to obtain the 3,7-dibromo-bromoethyl-phenazine intermediate 3 shown in Formula 3; The reaction formula is: Where X is oxygen, sulfur, or selenium; (2) The intermediate 3 obtained in step (1) is subjected to an Arbuzov reaction with triethyl phosphonate to obtain the phenazine intermediate 4 containing diethyl phosphonate as shown in Formula 4. The reaction formula is: (3) The intermediate 4 obtained in step (2) is subjected to a Suzuki reaction using the borate ester derivative shown in Formula 5 to obtain a diethyl phosphonate phenazine intermediate 6 with an R1 group; wherein the R1 group in Formula 5 is benzaldehyde or methyl sulfone; the molar ratio of the compound of Formula 5 to the compound of Formula 4 is greater than or equal to 2:

1. The reaction formula is: (4) Use bromotrimethylsilane to hydrolyze intermediate 6 to obtain a phosphonic acid self-assembled molecule that is used in perovskite light-emitting diodes and has both hole transport and perovskite passivation effects. When the self-assembled molecule has a structure as shown in general formula A-1, and R1 and R2 are the same, the preparation method includes the following steps: (1) Using 3,6-dibromocarbazole as shown in Formula 1 as a raw material, and combined with dibromoethane as a raw material shown in Formula 2, a nucleophilic substitution reaction is carried out to obtain 3,6-dibromo-bromoethyl-carbazole intermediate 3 as shown in Formula 3; The reaction formula is: Where X is oxygen, sulfur, or selenium; (2) The intermediate 3 obtained in step (1) is subjected to an Arbuzov reaction with triethyl phosphonate to obtain carbazole intermediate 4 with diethyl phosphonate as shown in Formula 4. The reaction formula is: (3) The intermediate 4 obtained in step (2) is subjected to a Suzuki reaction using the borate ester derivative shown in Formula 5 to obtain carbazole intermediate 6 with an R1 group; wherein the R1 group in Formula 5 is benzaldehyde group or methyl sulfone group; the molar ratio of the compound of Formula 5 to the compound of Formula 4 is greater than or equal to 2:

1. The reaction formula is: (4) Using bromotrimethylsilane to hydrolyze intermediate 6, a phosphonic acid self-assembled molecule with dual functions of hole transport and perovskite passivation can be obtained.

3. The method for preparing a phosphonic acid self-assembled molecule for perovskite light-emitting diodes, as described in claim 1, and possessing both hole transport and perovskite passivation effects, is characterized in that... When the self-assembled molecule has a structure as shown in one of general formulas A-2 to A-4, and R1 and R2 are different, the preparation method includes the following steps: S1. Using the 3,7-dibromophenazine derivative shown in Formula 1 as a starting material, and combined with the dibromoethane shown in Formula 2, a nucleophilic substitution reaction is carried out to obtain the 3,7-dibromo-bromoethyl-phenazine intermediate 3 shown in Formula 3; The reaction formula is: Where X is oxygen, sulfur, or selenium; S2. The intermediate 3 obtained in step S1 is subjected to an Arbuzov reaction with triethyl phosphonate to obtain the phenazine intermediate 4 containing diethyl phosphonate as shown in Formula 4. The reaction formula is: S3. Using the borate ester derivative shown in Formula 5, intermediate 4 obtained in step S2 undergoes a Suzuki reaction to obtain diethyl phosphonate phenazine intermediate 7 with an R1 group; wherein, the R1 group in Formula 5 is benzaldehyde or methyl sulfone; the molar ratio of compound 5 to compound 4 is less than or equal to 1:1 and greater than or equal to 0.5:

1. The reaction formula is: S4. The intermediate 7 obtained in S3 is subjected to a Suzuki reaction using the borate ester derivative shown in Formula 5' to obtain a diethyl phosphonate phenazine intermediate 8 with R1 and R2 groups; wherein, the R2 group in Formula 5' is selected from benzaldehyde or methyl sulfone and is different from the R1 group; the molar ratio of the compound of Formula 5' to the compound of Formula 7 is greater than or equal to 1:1; The reaction formula is: S5. By using bromotrimethylsilane to hydrolyze intermediate 8, a phosphonic acid self-assembled molecule with dual functions of hole transport and perovskite passivation can be obtained for use in perovskite light-emitting diodes. When the self-assembled molecule has a structure as shown in general formula A-1, and R1 and R2 are different, the preparation method includes the following steps: S1. Using 3,6-dibromocarbazole as shown in Formula 1 as a raw material, and combining it with dibromoethane as a raw material shown in Formula 2, a nucleophilic substitution reaction is carried out to obtain 3,6-dibromo-bromoethyl-carbazole intermediate 3 as shown in Formula 3; The reaction formula is: Where X is oxygen, sulfur, or selenium; S2. The intermediate 3 obtained in step S1 is subjected to an Arbuzov reaction with triethyl phosphonate to obtain carbazole intermediate 4 containing diethyl phosphonate as shown in Formula 4. The reaction formula is: S3. Using the borate ester derivative shown in Formula 5, intermediate 4 obtained in step S2 undergoes a Suzuki reaction to obtain carbazole intermediate 7 containing the R1 group; wherein, the R1 group in Formula 5 is benzaldehyde or methyl sulfone; the molar ratio of compound 5 to compound 4 is less than or equal to 1:1 and greater than or equal to 0.5:

1. The reaction formula is: S4. The intermediate 7 obtained from S3 is subjected to a Suzuki reaction using the borate ester derivative shown in Formula 5' to obtain a carbazole diethyl phosphonate intermediate 8 with R1 and R2 groups; wherein, the R2 group in Formula 5' is selected from benzaldehyde or methyl sulfone and is different from the R1 group; the molar ratio of the compound of Formula 5' to the compound of Formula 7 is greater than or equal to 1:1; The reaction formula is: S5. By using bromotrimethylsilane to hydrolyze intermediate 8, a phosphonic acid self-assembled molecule with dual functions of hole transport and perovskite passivation can be obtained for use in perovskite light-emitting diodes.

4. The preparation method according to claim 2 or 3, characterized in that, In step (1) or step S1, the nucleophilic substitution reaction is carried out in a solvent system with the participation of tetrabutylammonium bromide and a base. Specifically, 3,6-dibromocarbazole raw material, dibromoethane raw material, tetrabutylammonium bromide, base and solvent are added to the reaction apparatus, and then air is purged using a protective gas. Then, the mixture is heated to reflux under the protection of the protective gas. After the reaction is complete, it is cooled to room temperature for purification and post-treatment to obtain 3,6-dibromo-bromoethyl-carbazole intermediate 3. Alternatively, the nucleophilic substitution reaction is carried out in a solvent system with the participation of tetrabutylammonium bromide and a base. Specifically, the 3,7-dibromophenazine derivative raw material, dibromoethane raw material, tetrabutylammonium bromide, base and solvent are added to the reaction apparatus, and then the air is purged with a protective gas. Then, the reaction is heated to reflux under the protection of the protective gas. After the reaction is complete, it is cooled to room temperature for purification and post-treatment to obtain 3,7-dibromo-bromoethyl-phenazine intermediate 3. The protective gas is nitrogen or argon; the base is an inorganic base; and the solvent is deionized water. The molar ratio of 3,6-dibromocarbazole, dibromoethane, tetrabutylammonium bromide, and the base to the volume of the solvent satisfies 1 mmol : 1-2 mmol : 0.1-0.3 mmol : 3-5 mmol : 5-10 ml; the molar ratio of 3,7-dibromophenazine derivative, dibromoethane, tetrabutylammonium bromide, and the base to the volume of the solvent satisfies 1 mmol : 1-2 mmol : 0.1-0.3 mmol : 3-5 mmol : 5-10 ml; the reaction time under reflux is 24-48 hours. In step (2) or step S2, the Arbuzov reaction is carried out in a solvent system. Specifically, 3,6-dibromo-bromoethyl-carbazole intermediate 3 and triethyl phosphonate are added to the reaction apparatus, air is purged using a protective gas, and then the reaction is heated to reflux under protective gas protection. After the reaction is complete, it is cooled to room temperature for purification and post-processing to obtain carbazole intermediate 4 containing diethyl phosphonate. Alternatively, the Arbuzov reaction is carried out in a solvent system. Specifically, 3,7-dibromo-bromoethyl-phenazine intermediate 3 and triethyl phosphonate are added to the reaction apparatus, air is purged using a protective gas, and then the reaction is heated to reflux under protective gas protection. After the reaction is complete, it is cooled to room temperature for purification and post-processing to obtain phenazine intermediate 4 containing diethyl phosphonate. The protective gas is nitrogen or argon. The molar ratio of 3,6-dibromo-bromoethyl-carbazole intermediate 3 to triethyl phosphonate is 1 mmol: 1-1.5 mmol; the molar ratio of 3,7-dibromo-bromoethyl-phenazine intermediate 3 to triethyl phosphonate is 1 mmol: 1-1.5 mmol; the reaction time under reflux is 24-48 hours. In step (4) or step S5, the hydrolysis reaction specifically involves adding intermediate 6, bromotrimethylsilane, and dioxane into the reaction apparatus, purging the air with a protective gas, and then heating to reflux under protective gas conditions. After the reaction is complete, the mixture is cooled to room temperature, deionized water is added, the mixture is stirred, and filtered to obtain a phosphonic acid self-assembled molecule that is used in perovskite light-emitting diodes and has both hole transport and perovskite passivation effects. Alternatively, the hydrolysis reaction specifically involves adding intermediate 8, bromotrimethylsilane, and dioxane into a reaction apparatus, purging the air with a protective gas, heating to reflux under protective gas conditions, cooling to room temperature after the reaction is complete, adding deionized water, stirring, and filtering to obtain a phosphonic acid self-assembled molecule that is bifunctional for perovskite light-emitting diodes and has both hole transport and perovskite passivation effects. The protective gas is nitrogen or argon. The molar ratio of intermediate 6 and bromotrimethylsilane to the volume of dioxane satisfies 1 mmol: 1-2 mmol: 10 ml; the molar ratio of intermediate 8 and bromotrimethylsilane to the volume of dioxane satisfies 1 mmol: 1-2 mmol: 10 ml; the reaction time under reflux is 48-72 hours; the amount of deionized water added is at least twice the volume of dioxane, and the stirring time is 2 hours.

5. The preparation method according to claim 4, characterized in that, In step (1) or step S1, the alkali is potassium hydroxide.

6. The preparation method according to claim 2, characterized in that, In step (3), the Suzuki reaction is carried out in a solvent system. Specifically, intermediate 4, the borate ester derivative shown in formula 5, palladium catalyst, base, ethanol, water and toluene are mixed, air is purged using a protective gas, and the reaction is heated under reflux under the protection of the protective gas. After cooling to room temperature, the mixture is purified to obtain carbazole intermediate 6 with R1 group. Alternatively, the Suzuki reaction is carried out in a solvent system, specifically by mixing intermediate 4, the borate ester derivative shown in Formula 5, a palladium catalyst, a base, ethanol, water, and toluene, purging the air with a protective gas, heating and refluxing under a protective gas atmosphere, cooling to room temperature, and then purifying to obtain diethyl phosphonate phenazine intermediate 6 with an R1 group. The protective gas is nitrogen or argon; the palladium catalyst is tetra(triphenylphosphine)palladium; and the base is potassium carbonate. The molar ratios of intermediate 4, the borate ester derivative shown in Formula 5, tetra(triphenylphosphine)palladium, and potassium carbonate to the volume ratios of ethanol, water, and toluene satisfy the following: 1 mmol: 2-2.5 mmol: 0.04-0.06 mmol: 2 mmol: 1 ml: 1 ml: 2 ml; the reaction time of the heating and reflux reaction is 12-48 hours.

7. The preparation method according to claim 3, characterized in that, In step S3, the Suzuki reaction is carried out in a solvent system. Specifically, intermediate 4, the borate ester derivative shown in Formula 5, palladium catalyst, base, ethanol, water, and toluene are mixed, air is purged using a protective gas, and the mixture is heated under reflux under protective gas protection. After cooling to room temperature, it is purified to obtain diethyl phosphonate carbazole intermediate 7 with R1 group. Alternatively, the Suzuki reaction is carried out in a solvent system, specifically by mixing intermediate 4, the borate ester derivative shown in Formula 5, a palladium catalyst, a base, ethanol, water, and toluene, purging the air with a protective gas, heating and refluxing under a protective gas atmosphere, cooling to room temperature, and then purifying to obtain diethyl phosphonate phenazine intermediate 6 with an R1 group. The protective gas is nitrogen or argon; the palladium catalyst is tetra(triphenylphosphine)palladium; and the base is potassium carbonate. The molar ratios of intermediate 4, the borate ester derivative shown in Formula 5, tetra(triphenylphosphine)palladium, and potassium carbonate to the volume ratios of ethanol, water, and toluene satisfy the following: 1 mmol : 0.5-1 mmol : 0.02-0.05 mmol : 2 mmol : 1 ml : 1 ml : 2 ml; the reaction time for the heating and reflux reaction is 12-48 hours. In step S4, the Suzuki reaction is carried out in a solvent system. Specifically, intermediate 7, the borate ester derivative shown in formula 5', palladium catalyst, base, ethanol, water, and toluene are mixed, air is purged using a protective gas, and the mixture is heated under reflux under protective gas protection. After cooling to room temperature, it is purified to obtain diethyl phosphonate carbazole intermediate 8 with R1 and R2 groups. Alternatively, the Suzuki reaction is carried out in a solvent system, specifically by mixing intermediate 7, the borate ester derivative shown in Formula 5', a palladium catalyst, a base, ethanol, water, and toluene, purging the air with a protective gas, heating and refluxing under a protective gas atmosphere, cooling to room temperature, and then purifying to obtain diethyl phosphonate phenazine intermediate 8 with R1 and R2 groups. The protective gas is nitrogen or argon; the palladium catalyst is tetra(triphenylphosphine)palladium; and the base is potassium carbonate. The molar ratios of intermediate 7, the borate ester derivative shown in Formula 5', tetra(triphenylphosphine)palladium, and potassium carbonate to the volume ratios of ethanol, water, and toluene satisfy the following: 1 mmol: 1-1.5 mmol: 0.02-0.05 mmol: 2 mmol: 1 ml: 1 ml: 2 ml; the reaction time of the heating and reflux reaction is 12-48 hours.

8. The application of a multifunctional layer formed by phosphonic acid self-assembled molecules, which is dual-functionalized for perovskite light-emitting diodes and possesses both hole transport and perovskite passivation effects, as described in claim 1, as a substitute for the hole transport layer in perovskite light-emitting diode devices, wherein the multifunctional layer can transport charge carriers and provide passivation; wherein, The multifunctional layer is located between the metal oxide electrode and the perovskite light-emitting layer, and is in direct contact with both the metal oxide electrode and the perovskite light-emitting layer. The perovskite material is lead-based perovskite.

9. The application as described in claim 8, characterized in that, The application can improve the external quantum efficiency and / or increase the brightness of perovskite light-emitting diode devices.

10. The application as described in claim 8, characterized in that, The perovskite light-emitting diode device comprises, in sequence: a metal oxide electrode, a multifunctional layer, a perovskite light-emitting layer, an electron transport layer, an electron injection layer, and a cathode.

11. The application as described in claim 10, characterized in that, The multifunctional layer is a monolayer; the perovskite in the perovskite luminescent layer is prepared by thermal evaporation; the electron transport layer is selected from TPBi, TmPyPB, and C. 60 The cathode is an Al electrode.

12. The application as described in claim 10, characterized in that, The thickness of the perovskite light-emitting layer is between 10-200 nm, the thickness of the electron transport layer is between 15-70 nm, and the thickness of the cathode is between 50-200 nm.

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