A compound for assembling a hole injection layer material and preparation and application thereof

Abstract

This invention discloses a compound for assembling hole injection layer materials, its preparation, and its application. The compound comprises a compound with the structure shown in formula (I), where n is an integer from 1 to 10. The preparation method employs a three-step process of nucleophilic substitution, Arbuzov reaction, and esterification. A helical type D1 with 10H-spiro[acridine-9,9'-fluorene] as the parent core and a non-helical type D2 with 9,9-diphenyl-9,10-dihydroacridine as the core are both introduced with phosphonic acid anchoring groups. This invention solves the problem of limited performance and difficulty in achieving both efficiency and lifetime in existing planar structures. The prepared compound is used to covalently bind to hydroxyl groups on the ITO surface to form a stable self-assembled monolayer, achieving precise modification and energy level matching of the ITO interface. Through the self-assembly advantages of the helical configuration, the device's operational stability is improved. 95 The lifespan is 142.8% longer than that of PEDOT:PSS.

Description

Technical Field

[0001] This invention relates to a method for preparing a compound for assembling a hole injection layer material, specifically to a compound for assembling a hole injection layer material and its preparation and application. Background Technology

[0002] Quantum dot light-emitting diodes (QLEDs) possess advantages such as high color purity, tunable emission wavelength, and compatible fabrication processes, making them promising candidates for applications in the display and lighting fields. The performance of QLED devices depends on the balance between carrier injection and transport. Problems such as low hole injection efficiency, poor interface matching, and energy level mismatch between the hole transport layer and the quantum dot layer are key factors limiting improvements in device efficiency, brightness, and lifetime.

[0003] Traditional hole injection materials such as PEDOT:PSS have problems such as strong acidity, strong hygroscopicity, easy corrosion of electrodes with long-term use, and interface stability. Conventional small molecule hole injection layer materials have poor modeling, are prone to crystallization, and are difficult to form dense and uniform films, resulting in increased leakage current and severe exciton quenching. Reference 1 (Liu Y., Yan M., Zhang K., Chen Y., He Y., Meng H., Huang Y., Zhang Y. Self-Assembled Carbazole-Phosphonate Hole-Injection Layer with a Dual-Modification Mechanism Enables High Efficient and Stable Blue Quantum-Dot Light-Emitting Diode. ACS Photonics, 2025, 12(8), 4540-4552. https: / / doi.org / 10.1021 / acsphotonics.5c00937) uses a carbazole phosphonate self-assembled layer to replace the traditional PEDOT:PSS to construct the hole injection layer of blue QLED, and selects the classic [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz) to construct a dual modification mechanism: on the one hand, 2PACz and ITO Surface chemical bonding reduces film surface roughness and passivates interface defect states. On the other hand, 2PACz forms intermolecular interactions with the TFB hole transport layer, optimizing the π-π stacking path, improving hole injection efficiency, and achieving carrier injection balance. The external quantum efficiency of the blue QLED based on 2PACz reaches 16.58%, and the device T50 lifetime is improved from 55 h for the PEDOT:PSS reference device to 148 h, significantly balancing device efficiency and operational stability. However, the 2PACz in Reference 1 is a rigid planar carbazole framework with strong intermolecular π-π stacking interactions, making it prone to molecular aggregation during self-assembly, and there is still room for improvement in film flatness. This study did not quantitatively characterize the molecular dipole moment and ITO work function regulation, focusing only on blue QLED optimization and not exploring the compatibility with green and red devices, thus limiting the device's color gamut and full-color display applications.

[0004] Helical conjugated molecules have a unique spatial structure, and molecules can achieve ordered self-assembly through π-π stacking and dipole interaction to form dense films with regular orientation and few defects. At the same time, their HOMO energy level can be flexibly controlled by modifying the framework, making them very suitable as hole injection layer materials. However, existing helical molecules have problems such as complicated synthesis routes, difficult purification, insufficient matching with QLED energy levels, and low hole mobility, which make it difficult to meet the requirements of high-performance QLED devices. Reference 2 (Wang W, Chen Q, Hua G, et al. Molecular engineering on hole injection self-assembled monolayers for superior RGB quantum dot light-emitting diodes[J]. TheInnovation Materials, 2025, 3: 100151. https: / / doi.org / 10.59717 / j.xinn-mater.2025.100151) describes the design of carbazole phosphonic acid self-assembled monolayers (SAMs) as hole injection layers for QLEDs through molecular engineering. Asymmetric conjugation and bromine atom substitution were performed on the benzo[a]carbazole core to precisely control the molecular dipole moment and achieve interface modification of the ITO substrate work function. The BCB-Br molecule constructs the optimal hole injection energy level matching. A red QLED based on this self-assembled layer achieved an external quantum efficiency of 23.3%, a low start-up voltage of 1.73 V, a power efficiency of 47.0 lm / W, and a current efficiency of 30.4 cd / A. However, the molecule in Reference 2 is still a planar benzocarbazole framework without a helical three-dimensional configuration, lacking intermolecular steric hindrance regulation, which limits the orderliness of the self-assembled thin film; relying solely on halogen single-site substitution to regulate the dipole moment results in a single molecular energy level and dipole regulation method with insufficient flexibility; the study focuses on the performance optimization of red light devices, without systematically reporting device operating lifetime and long-term interface stability data, and the molecular synthesis requires multiple functional group derivation steps, resulting in high synthesis costs, making it difficult to achieve the synergistic development of high-efficiency and long-life devices. Summary of the Invention

[0005] The purpose of this invention is to provide a compound for assembling hole injection layer materials, its preparation, and its application. This solves the problem of limited performance and difficulty in achieving both efficiency and lifetime in existing planar structures. A helical D1 with a 10H-spiro[acridin-9,9'-fluorene] core and a non-helical D2 with 9,9-diphenyl-9,10-dihydroacridin as the core are both introduced with phosphonic acid (-PO(OH)2) anchoring groups for covalent bonding with hydroxyl groups on the ITO surface, forming a stable self-assembled monolayer. This achieves precise modification and energy level matching of the ITO interface. Through the self-assembly advantages of the helical configuration, the device's operational stability is improved. 95 The lifespan is 142.8% longer than that of PEDOT:PSS.

[0006] To achieve the above objectives, the present invention provides a compound for assembling hole injection layer materials, the compound comprising a compound with the structure shown in formula (I): In equation (Ⅰ), n is an integer from 1 to 10.

[0007] Preferably, the compound comprises compounds with structures as shown in formulas (II) and (III): In equations (II) and (III), n is an integer from 1 to 8.

[0008] Preferably, n is 4; the molecular dipole moment of the compound with the structure shown in formula (II) is ≥1.4 D; the molecular dipole moment of the compound with the structure shown in formula (III) is ≥1.5 D.

[0009] This invention provides a method for preparing the compound as described above, the method comprising: (1) Under the protection of an inert gas, acridine compounds, anhydrous aprotic polar organic solvent and NaH were mixed and stirred, and bromoalkane was added to carry out N-nucleophilic substitution reaction. The mixture was cooled, quenched, extracted, dried, concentrated by rotary evaporation, and purified by column chromatography to obtain intermediate 1. (2) Intermediate 1 was mixed with phosphite and subjected to Arbuzov reaction at 140 °C. The mixture was then distilled under reduced pressure to obtain intermediate 2. (3) Dissolve intermediate 2 in anhydrous chlorinated hydrocarbon, add bromosilane and stir to carry out ester decomposition reaction, remove solvent by vacuum evaporation, add methanol and reflux reaction; concentrate by rotary evaporation, recrystallize and dry under vacuum.

[0010] Preferably, the acridine compounds include spiro[acridine-fluorene] compounds and dihydroacridine compounds; the anhydrous aprotic polar organic solvent is N,N-dimethylformamide.

[0011] Preferably, the spiro[acrylidine-fluorene] compound is 10H-spiro[acrylidine-9,9'-fluorene]; the dihydroacrylidine compound is 9,9-diphenyl-9,10-dihydroacrylidine.

[0012] Preferably, the phosphite is triethyl phosphite, the chlorinated hydrocarbon is dichloromethane, the bromosilane is trimethylbromosilane, and the bromoalkane is 1,4-dibromobutane.

[0013] Preferably, the molar ratio of the acridine compound, NaH and bromoalkane is 1:(1~1.5):(1~2); the molar ratio of intermediate 1 to phosphite is 1:(15~25); and the molar ratio of intermediate 2 to bromosilane is 1:(2~4).

[0014] This invention provides an application of the compound as described above in the fabrication of quantum dot light-emitting diodes.

[0015] Preferably, the quantum dot light-emitting diode device adopts a front-mounted structure, comprising: indium tin oxide, a self-assembled monolayer, a hole injection layer, a quantum dot light-emitting layer, a zinc-magnesium oxide alloy layer, and aluminum; wherein, the raw material for preparing the self-assembled monolayer comprises a compound with the structure shown in formula (I); the raw material for preparing the hole injection layer comprises poly(9,9-dioctylfluorene-alt-carbazole); and the aluminum is the cathode.

[0016] More preferably, the raw materials for preparing the self-assembled monolayer comprise compounds with structures as shown in Formula (II) and compounds with structures as shown in Formula (III).

[0017] More preferably, the method for self-assembling a hole injection layer includes: (1) The ITO glass substrate was ultrasonically cleaned in sequence with cleaning agent, deionized water, acetone and isopropanol, dried with nitrogen, and treated with ultraviolet ozone to activate the hydroxyl groups on the ITO surface, thus obtaining an activated ITO substrate. (2) Prepare an ethanol solution containing the compound with the structure shown in Formula (II) or the compound with the structure shown in Formula (III), immerse the activated ITO substrate in the prepared ethanol solution containing the compound with the structure shown in Formula (II) or the compound with the structure shown in Formula (III), and self-assemble at room temperature for 24 h. The concentration of the compound with the structure shown in formula (II) or the compound with the structure shown in formula (III) in the prepared ethanol solution is 1 mmol / L. (3) Take out the substrate, rinse with ethanol to remove unadsorbed molecules, blow dry with nitrogen, and anneal at 120°C for 10 min to obtain a novel spiral self-assembled hole injection layer material for high-performance QLED.

[0018] The compounds with the structure shown in Formula (II) or Formula (III) have phosphonic acid anchoring groups that self-assemble with the ITO surface through PO-In chemical bonds. The film quality, surface roughness, work function, interfacial bonding force, and device performance are highly dependent on four major process parameters: solution concentration, self-assembly time, annealing temperature, and annealing time. Any deviation of any parameter from the optimal value will significantly disrupt the ordered monolayer assembly of SAM.

[0019] This invention discloses a compound for assembling a hole injection layer material, its preparation, and its application. This invention solves the problems of limited performance and difficulty in achieving both efficiency and lifetime in existing planar structures, and has the following advantages: 1. This invention employs a three-step method of "nucleophilic substitution-Arbuzov reaction-ester decomposition". 10H-spiro[acridin-9,9'-fluorene] and 9,9-diphenyl-9,10-dihydroacridin are used as starting materials (neutral small organic molecules, non-acidic and non-corrosive to ITO electrodes). A brominated side chain is introduced through N-alkylation, followed by an Arbuzov reaction to generate a phosphate ester. Finally, acid hydrolysis is used to achieve ester decomposition, yielding a helical D1 (molecular dipole moment 1.57 D) with 10H-spiro[acridin-9,9'-fluorene] as the core and a non-helical D2 (molecular dipole moment 1.48 D) with 9,9-diphenyl-9,10-dihydroacridin as the core. Both introduce phosphonic acid (-PO(OH)2) anchoring groups for covalent bonding with the hydroxyl groups on the ITO surface, forming a stable self-assembled monolayer. Furthermore, this invention optimizes reaction conditions (temperature, solvent, catalyst), reduces side reactions, and employs a two-step purification process of recrystallization and column chromatography to increase the product yield to over 70% and the purity to over 98%, meeting the requirements of device applications.

[0020] 2. This invention enhances the molecular dipole moment through the steric hindrance and electronic effects of the helical configuration, ultimately achieving a molecular dipole moment of 1.57 D for D1. This successfully modulates the ITO work function to -5.51 eV, which is highly matched with the PF8Cz work function (-5.33 eV). The hole injection barrier is only 0.18 eV, far lower than that of D2 (-5.44 eV). Furthermore, DFT calculations verify that the binding energy between D1 and the ITO surface is -0.970 eV, which is higher than that of D2 (-0.844 eV), demonstrating that the binding of helical molecules to ITO is more stable, resulting in a denser self-assembled film. This invention utilizes the steric hindrance of helical molecules to inhibit excessive molecular aggregation, optimizes the self-assembly process, and guides the orderly arrangement of molecules. The root mean square roughness (RMS) of the D1 self-assembled film is only 3.66 nm, which is much lower than the 6.27 nm of the ITO substrate and the 4.13 nm of D2. At the same time, the contact angle test verifies that the contact angle of the ITO surface modified by D1 is 57.95°, which is significantly higher than the 46.1° of D2 and the 45.7° of pure ITO. This proves that the self-assembled film is denser and hydrophobic, which can effectively block water vapor and improve interface stability.

[0021] 3. This invention is the first to use helical acridine phosphonic acid (SAM) in the hole injection layer of QLEDs, achieving precise modification and energy level matching of the ITO interface; the self-assembly process is simple, requiring no complex equipment, and is compatible with existing QLED mass production lines without the need for additional equipment; the energy level modulation and interface passivation effects of D1 on the ITO surface are verified through UPS and XPS characterization, ultimately achieving a comprehensive breakthrough in the performance of the QLED device (ITO / SAM / PF8Cz / QDs / ZnMgO / Al): the start-up voltage of the D1-based QLED is as low as 1.61V, and the maximum brightness reaches 240,500 cd / m². 2 External quantum efficiency (EQE) 26.58%, current efficiency (CE) 27.58 cd / A, T 95 Working life up to 68 hours (@19600 cd / m³) 2 It is superior to D2 and PEDOT:PSS based devices in all aspects. Attached Figure Description

[0022] Figure 1 This invention relates to the chemical structures of helical D1 and non-helical D2 molecules, the structure of QLED devices, and related characterization spectra.

[0023] Figure 2 This is a schematic diagram of the XPS characterization spectra and molecular electrostatic potential surface and dipole moment of the D1 and D2 materials of the present invention.

[0024] Figure 3 The diagram shows the water contact angle, AFM morphology, and surface potential distribution of the ITO / D1 / D2 self-assembled substrate of this invention.

[0025] Figure 4 This document shows the structure of the QLED device, its emission photographs, and related test curves of its photoelectric performance.

[0026] Figure 5 For the present invention D1 1 H NMR nuclear magnetic resonance spectrum and 13 C10 NMR spectrum.

[0027] Figure 6 For the present invention D2 1 H NMR nuclear magnetic resonance spectrum and 13 C10 NMR spectrum.

[0028] Figure 7 This is the mass spectrometry analysis chromatogram of D1 of the present invention.

[0029] Figure 8 This is the mass spectrometry analysis chromatogram of D2 in this invention.

[0030] Figure 9 The present invention provides the HOMO / LUMO energy level diagrams of D1 and D2 obtained by DFT calculation.

[0031] Figure 10 The TGA curves for D1 and (red) D2 of this invention are shown. The decomposition temperatures of D1 and D2 are 247℃ and 194℃, respectively.

[0032] Figure 11 The image shows the cross-sectional profile of the corresponding atomic force microscope (AFM) according to the present invention, where (a) is ITO / D1; and (b) is ITO / D2.

[0033] Figure 12 This is the normalized EL spectrum of the QLED device based on D1 and D2 according to the present invention.

[0034] Figure 13 This is the band structure diagram of the quantum dot light-emitting diode (QLED) based on D1, D2, and PEDOT:PSS of the present invention. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1 A method for preparing a novel spiral self-assembled hole injection layer material for high-performance QLEDs, the method comprising: 1. Synthesis of helical D1 and non-helical D2 The synthesis of helical D1 (10-(4-phosphonobutyl)-10H-spiro[acridin-9,9'-fluorene]) is performed as follows: Step 1: N-nucleophilic substitution reaction to synthesize intermediate 1 Under nitrogen protection, 10H-spiro[acridin-9,9'-fluorene] (1.0 eq) was dissolved in anhydrous DMF, and NaH (1.2 eq) was added. The mixture was stirred at room temperature for 1 h. 1,4-Dibromobutane (1.5 eq) was added, and the reaction was carried out for 12 h. After the reaction was completed, the mixture was cooled to room temperature, quenched with water, extracted with dichloromethane, dried over anhydrous sodium sulfate, concentrated by rotary evaporation, and purified by column chromatography (petroleum ether / dichloromethane) to give a white solid intermediate 1 (10-(4-bromobutyl)-10H-spiro[acridin-9,9'-fluorene]) with a yield of 78%. Dichloromethane was purchased from Sinopharm Group in 500 mL containers; the DMF was purchased from Innochem and was anhydrous DMF with 99.0% water ≤ 30 ppm.

[0037] The 1H NMR spectrum of intermediate 1 (10-(4-bromobutyl)-10H-spiro[acridin-9,9'-fluorene]) is as follows: 1 H NMR (400 MHz, DMSO- d6 ) δ 7.97 (d, J = 7.6 Hz, 2H), 7.43 (td, J = 7.4,1.5 Hz, 2H), 7.31 (m, 8H), 6.67 (m, 2H), 6.28 (dd, J = 7.7, 1.4 Hz, 2H), 4.24(m, 2H), 3.79 (t, J = 6.6 Hz, 2H), 2.24 (m, 2H), 2.09 (m, 2H).

[0038] 13 C NMR (151 MHz, DMSO- d6 ) δ 155.52 , 140.35 , 139.09 , 128.83 ,128.35 , 127.05 , 126.43 , 125.57 , 120.83 , 120.48 , 113.61 , 57.05 , 35.42, 30.11, 24.24.

[0039] Step 2: Arbuzov reaction, synthesis of intermediate 2 Intermediate 1 (1.0 eq) was mixed with triethyl phosphite (20.0 eq) and the mixture was heated to 140 °C and reacted for 24 h. After the reaction was completed, excess triethyl phosphite was removed by vacuum distillation to obtain a white solid intermediate 2 (10-(4-diethoxyphosphonobutyl)-10H-spiro[acridine-9,9'-fluorene]), which was separated by column chromatography with a yield of 92%.

[0040] The 1H NMR spectrum of intermediate 2 (10-(4-diethoxyphosphonobutyl)-10H-spiro[acridin-9,9'-fluorene]) is as follows: 1H NMR (400 MHz, CDCl3) δ 7.75 (d, J = 7.6 Hz, 2H), 7.33 (td, J = 7.4, 1.2 Hz, 2H), 7.25 (t, J = 3.7 Hz, 2H), 7.21 (m, 4H), 7.01 (d, J = 7.8 Hz, 2H), 6.62 (m, 2H), 6.40 (dd, J = 7.7, 1.6 Hz, 2H), 4.22 (m, 4H), 4.10 (m, 2H), 2.13(m, 2H), 1.93 (ddd, J = 13.5, 7.9, 4.2 Hz, 4H), 1.36 (t, J = 7.1 Hz, 6H).

[0041] 13 C NMR (151 MHz, CDCl3) δ 155.74, 140.30, 139.25, 128.33, 128.08, 126.80, 125.65, 120.35, 119.95, 112.51, 61.76, 57.14, 45.87, 26.76, 20.37, 16.67.

[0042] Step 3: Ester decomposition reaction to synthesize the target product D1 Intermediate 2 (1.0 eq) was dissolved in anhydrous dichloromethane, and trimethylbromosilane (3.0 eq) was added. The mixture was stirred at room temperature for 24 h. The solvent was removed by vacuum evaporation, methanol was added, and the mixture was refluxed for 4 h. The mixture was concentrated by rotary evaporation, recrystallized (ethyl acetate / n-hexane), and dried under vacuum to give the white solid target product D1 (helical D1, abbreviated as D1), with an overall yield of 68%.

[0043] Structural characterization of helical D1 (10-(4-phosphonobutyl)-10H-spiro[acridin-9,9'-fluorene]): 1 H NMR, 13 CNMR, 31 The P NMR and MALDI-TOF-MS data are consistent with the target molecule; the molecular dipole moment is 1.57 D (DFT calculation).

[0044] The 1H NMR spectrum of helical D1 (10-(4-phosphonobutyl)-10H-spiro[acridin-9,9'-fluorene]) is as follows: 1 H NMR (600 MHz, DMSO- d6 ) δ 7.92 (d, J = 7.6 Hz, 2H), 7.38 (td, J = 7.6,1.1 Hz, 2H), 7.25 (m, 8H), 6.62 (m, 2H), 6.23 (dd, J = 7.7, 1.3 Hz, 2H), 4.15(m, 2H), 1.97 (t, J = 11.2 Hz, 2H), 1.77 (ddd, J = 25.2, 16.7, 7.7 Hz, 4H).

[0045] 13 C NMR (151 MHz, DMSO- d6 ) δ 155.52 , 140.46 , 139.07 , 128.82 ,128.41 , 128.23 , 126.99 , 126.41 , 125.60 , 120.77 , 120.37 , 113.66 , 26.49, 20.87. HRMS (ESI-TOF) m / z: [M+H] + Calculated for C 29 H 26 NO3P: 468.50769; Found: 468.17289.

[0046] like Figure 5 As shown, the present invention D1 1 H NMR nuclear magnetic resonance spectrum and 13 C10 NMR spectrum.

[0047] like Figure 7 The mass spectrometry analysis diagram of the present invention, D1, is shown.

[0048] The synthesis of non-helical D2 (10-(4-phosphonobutyl)-9,9-diphenyl-9,10-dihydroacridine) is basically the same as that of helical D1, with the following differences: The 10H-spiro[acridine-9,9'-fluorene] was replaced with 9,9-diphenyl-9,10-dihydroacridine, and the rest of the process was carried out in the same manner as the synthesis of helical D1, finally yielding the white solid target product D2 (i.e., non-helical D2, abbreviated as D2), with an overall yield of 65%.

[0049] Structural characterization of non-helical D2 (10-(4-phosphonobutyl)-9,9-diphenyl-9,10-dihydroacridine) by 1H NMR: 1 H NMR, 13 C NMR, 31 The 1H NMR and MALDI-TOF-MS data are consistent with the target molecule; the molecular dipole moment is 1.48 D (DFT calculation). The 1H NMR spectra of the two intermediates for synthesizing the non-helical D2 (10-(4-phosphonobutyl)-9,9-diphenyl-9,10-dihydroacridine) and the non-helical D2 (10-(4-phosphonobutyl)-9,9-diphenyl-9,10-dihydroacridine) are as follows:

[0050] 1 H NMR (400 MHz, CDCl3)δ 7.27 (m, 8H), 7.01 (d, J = 8.2 Hz, 2H), 6.93(m, 8H), 3.90 (t, J = 6.4 Hz, 2H), 2.95 (t, J = 6.3 Hz, 2H), 1.72 (m, 2H), 1.12(m, 2H).

[0051] 13C NMR (151 MHz, CDCl3)δ 146.2 , 141.8 , 132.5 , 130.5 , 130.4 ,127.7 , 127.2 , 126.51 , 119.9 , 112.9 , 77.5 , 77.2 , 76.8 , 57.7 , 43.64 ,33.9 , 28.9 , 24.9。

[0052] 1 H NMR (400 MHz, CDCl3) δ 7.27 (m, 2H), 7.18 (dd, J = 5.8, 3.8 Hz, 6H),6.97 (d, J = 8.2 Hz, 2H), 6.91 (m, 8H), 4.13 (m, 4H), 3.88 (m, 2H), 1.65 (m,4H), 1.37 (m, 8H)。

[0053] 13 CNMR (151 MHz, CDCl3) δ 146.27 , 141.53 , 131.89 , 130.34 , 127.59 ,127.18 , 126.35 , 119.81 , 112.76 , 61.51 , 57.08 , 44.93 (s), 26.89 , 19.76, 16.57。

[0054] 1 H NMR (600 MHz, DMSO- d6 ) δ 7.31 (m, 8H), 7.14 (d, J = 8.2 Hz, 2H),6.89 (t, J = 7.4 Hz, 2H), 6.81 (m, 4H), 6.69 (dd, J = 7.7, 1.4 Hz, 2H), 3.88 (m,2H), 1.63 (m, 2H), 1.45 (m, 4H)。

[0055] 13 C NMR (151 MHz, DMSO- d6) δ 146.46 , 141.15 , 130.62 , 130.16 ,130.00 , 128.11 , 127.88 , 126.85 , 119.99 , 113.36 , 26.40 , 20.41. HRMS(ESI-TOF) m / z: [M+H] + Calculated for C 29 H 28 NO3P: 470.52547; Found: 470.18809.

[0056] like Figure 6 As shown, the present invention D2 1 H NMR nuclear magnetic resonance spectrum and 13 C10 NMR spectrum.

[0057] like Figure 8 The mass spectrometry analysis diagram of the present invention, D2, is shown.

[0058] 2. Preparation of self-assembled hole injection layer (1) The ITO glass substrate was ultrasonically cleaned for 15 min by cleaning agent, deionized water, acetone and isopropanol in sequence, dried with nitrogen, and treated with ultraviolet ozone for 15 min to activate the hydroxyl groups on the ITO surface, thus obtaining an activated ITO substrate. (2) Prepare an ethanol solution of D1 / D2 (the concentration of D1 / D2 in the solution is 1 mmol / L), immerse the activated ITO substrate in the prepared ethanol solution of D1 / D2, and self-assemble at room temperature for 24 h. (3) Take out the substrate, rinse with ethanol to remove unadsorbed molecules, blow dry with nitrogen, and anneal at 120°C for 10 min to obtain ITO / D1 and ITO / D2 self-assembled substrates, which are the new spiral self-assembled hole injection layer materials for high-performance QLED.

[0059] Example 2 The preparation method of the self-assembled hole injection layer is basically the same as that in Example 1, with the following differences: In step (2), the concentration of D1 / D2 in the solution is 0.2 mmol / L, 0.5 mmol / L, 1.5 mmol / L or 2.0 mmol / L.

[0060] Analysis of the results from Example 1 revealed that when the concentration of D1 / D2 in the solution was <1 mmol / L, the number of D1 / D2 molecules in the ethanol solution was insufficient, the adsorption sites on the ITO surface could not be fully occupied, resulting in incomplete SAM assembly and disordered molecular arrangement. AFM measurements showed a significant increase in RMS roughness (higher than D1 3.66 nm and D2 4.13 nm in Example 1); a decrease in contact angle and a deterioration in surface hydrophobicity; a shallower work function in the UPS test and an increased hole injection barrier; an increase in device turn-on voltage and a significant decrease in brightness and EQE, indicating severe interfacial charge accumulation. In Example 1, when the concentration of D1 / D2 in the solution was 1 mmol / L, the molecules just saturated and occupied the active sites on the ITO surface, forming a highly ordered, monomolecular, uniform, and dense film; the PO-In bond was the most stable, with the optimal adsorption energy (D1 −0.970 eV, D2 −0.844 eV); the surface roughness was the lowest, hydrophobicity was optimal, energy level matching was perfect, and charge balance was optimal. When the concentration of D1 / D2 in the solution is >1 mmol / L, the solution becomes supersaturated, which easily leads to multilayer molecular stacking, agglomeration and precipitation, resulting in defects and pinholes; the transmittance of the film decreases and the surface roughness increases; excess unbonded molecules remain at the interface, increasing leakage current; the reverse current of the device increases and the lifetime decays faster, and high concentrations easily induce molecular aggregation, leading to dipole moment disorder and loss of the energy level regulation advantage of spirocyclic D1.

[0061] Example 3 The preparation method of the self-assembled hole injection layer is basically the same as that in Example 1, with the following differences: In step (2), the self-assembly time at room temperature is 0.5 h, 1 h, 3 h or 4 h.

[0062] Analysis of the results from Example 1 revealed that: When the assembly time is too short (0.5 / 1 h), the bonding between the phosphonic acid groups and the ITO surface is insufficient, resulting in low SAM coverage and disordered molecular arrangement; the In 3d and P 2p peaks in XPS show small shifts, indicating weak interfacial interactions; the work function modulation effect is poor, and the hole injection capability is insufficient. When the assembly time is too long (3 / 4 h), the assembled ordered monolayer undergoes rearrangement, collapse, and multilayer adsorption, introducing interfacial defects; surface homogeneity is disrupted, nonradiative recombination of charge carriers increases, and device efficiency and stability decrease. Therefore, only when the assembly time is 2 h can saturated ordered monomolecular self-assembly be achieved, with complete bonding and no excess accumulation.

[0063] Example 4 The preparation method of the self-assembled hole injection layer is basically the same as that in Example 1, with the following differences: In step (3), the annealing temperature is 80 ℃, 120 ℃, 180 ℃ or 200 ℃.

[0064] Analysis of the results from Example 1 revealed that low-temperature annealing (80 / 120 °C) resulted in incomplete solvent evaporation, restricted molecular chain movement, incomplete solidification of PO-In chemical bonds, high internal stress in the SAM film, and weak interfacial bonding; it also made the film susceptible to moisture corrosion, leading to poor long-term device stability. High-temperature annealing (180 / 200 °C) exceeded the thermal stability tolerance of D1 / D2 (D1 decomposition temperature 247 °C, D2 194 °C), causing D2 to easily decompose and D1 to suffer molecular configuration destruction; the rigid spirocyclic structure collapsed, molecular dipole moments became disordered, and work function regulation failed; the film cracked, and roughness increased dramatically. Therefore, the 150 °C setting in Example 1 completely removed the solvent, promoted dense solidification of chemical bonds, and did not damage the molecular framework and spirocyclic configuration.

[0065] Example 5 The preparation method of the self-assembled hole injection layer is basically the same as that in Example 1, with the following differences: In step (3), the annealing time is 10 min, 20 min, 40 min or 60 min.

[0066] Analysis of the results from Example 1 reveals that insufficient annealing time (10 / 20 min) results in incomplete solvent removal, leading to micropores and defects in the SAM, allowing moisture to easily penetrate and corrode the ITO electrode, replicating the hygroscopic corrosion drawbacks of PEDOT:PSS. Excessive annealing time (40 / 60 min) disrupts the thermally induced molecular thermal relaxation and ordered arrangement, weakens the interfacial dipole interaction, reduces hole injection efficiency, and increases device leakage current.

[0067] Experiment Example 1: Structural Performance Characterization The structures of the spiral D1, non-spiral D2, and ITO / D1 / D2 self-assembled substrates prepared in Example 1 were analyzed.

[0068] like Figure 1 As shown, this invention relates to the chemical structures of helical D1 and non-helical D2 molecules, the structure of QLED devices, and related characterization spectra. (a) shows the chemical structures of helical D1 and non-helical D2 molecules; (b) shows the UV photoelectron spectroscopy (UPS); (c) shows the energy level alignment diagram; and (d) shows the device structure and DFT calculations. The left side shows the device structure of a quantum dot light-emitting diode (QLED): from bottom to top, it is glass / ITO / SAM / PF8Cz / QDs / ZnMgO / Al, with SAM as a hole injection / transport modification layer. The right side shows the adsorption model calculated by DFT theory, the adsorption configurations of D1 and D2 molecules on the ITO (or metal oxide) surface, and the adsorption energy (E). ads (a) D1 is -0.970 eV, D2 is -0.844 eV (the larger the negative value, the more stable the adsorption); (e) is X-ray photoelectron spectroscopy (XPS). Figure 1 As shown in (a), the chemical structure diagrams of D1 and D2 demonstrate the difference in molecular skeletons between the spirocyclic D1 and the non-spirocyclic D2. D1 contains a rigid spirocyclic configuration of [acridine-9,9'-fluorene], while D2 has a planar structure of 9,9-diphenylacridine without a spirocyclic ring. The spirocyclic configuration endows D1 with steric hindrance, more regular molecular conjugation, and stronger thermal stability; the rigid skeleton inhibits molecular aggregation, which is conducive to the formation of low-roughness ordered films; and it provides a structural basis for larger molecular dipole moments and deeper work functions. Figure 1 As shown in (b), the UPS spectra of ITO / D1, ITO / D2, and PF8Cz were analyzed using ultraviolet photoelectron spectroscopy to determine the HOMO and Fermi levels of each system. The UPS measurements showed that the HOMO of D1 was -5.97 eV and the Fermi level of the WF was -5.51 eV, deeper than that of D2 (-5.91 eV, WF: -5.44 eV). This deeper work function raises the Fermi level on the ITO surface, reducing the hole injection barrier between ITO and PF8Cz. Simultaneously, it suppresses the reverse migration of electrons towards the anode, achieving charge injection balance and addressing the shortcomings of insufficient hole injection and charge imbalance in traditional PEDOT:PSS. Figure 1 As shown in (c), the schematic diagram of the SAM bandgap position under vacuum reference visualizes the D1 / D2 level arrangement and its matching relationship with the PF8Cz transport layer level. The D1 level exhibits a stepped matching, constructing progressively oriented hole transport channels; the level alignment is significantly better than D2 and PEDOT:PSS, greatly reducing the interface barrier and improving hole transport efficiency. Figure 1 As shown in (d), the SAM-modified ITO QLED device structure, combined with DFT calculations of D1 / D2 and the ITO bonding model, gives the device stacked structure ITO / SAM / PF8Cz / QDs / ZnMgO / Al; the DFT simulation shows the adsorption configuration of molecules on the ITO (100) surface. The DFT adsorption energy D1 (−0.970 eV) > D2 (−0.844 eV), proving that D1 has a stronger interface bonding with ITO; the phosphonic acid hydroxyl group forms a stable PO-In covalent bond with ITO, resulting in better anchoring and a much higher interface stability than the physically adsorbed PEDOT:PSS. Figure 1 As shown in (e), the In 3d XPS spectra of ITO loaded with D1 / D2 characterize the binding energy shift of In elements on the ITO substrate, reflecting the strength of interfacial interactions. The In 3d binding energy shift is more significant after D1 modification, proving that the electronic interaction between D1 and ITO is stronger and the interfacial charge transfer is more complete; it effectively passivates oxygen vacancy defects on the ITO surface, reduces nonradiative recombination, and improves device efficiency and stability.

[0069] like Figure 2The diagram shows the XPS characterization spectra and molecular electrostatic potential surface and dipole moment of materials D1 and D2 in this invention. (a) is the P 2p XPS spectrum of D1 / D2; (b) is the O 1s XPS spectrum of D1 / D2; and (c) is the electrostatic potential surface (EPS) and dipole moment of D1 / D2. Figure 2 As shown in (a), the bonding mode of the phosphoric acid group P element (PO4) can be determined. 3- PO3 4- The greater shift of the P 2p peak of D1 towards higher binding energies indicates a tighter bond between the D1 phosphonic acid groups and ITO, resulting in stronger covalent interactions and superior film adhesion and moisture resistance. Figure 2 As shown in (b), the peak fitting reveals characteristic peaks such as In-OP, In-OH, oxygen vacancies, and adsorbed water. The oxygen vacancy peak intensity of D1 is significantly lower, proving that D1 can effectively passivate oxygen vacancy defects on the ITO surface; hydroxyl protonation forms strong PO-In bonds, reducing the interface defect state density and lowering leakage current and carrier recombination losses. Figure 2 As shown in (c), the DFT calculations show the molecular electrostatic potential distribution and dipole moment magnitudes (D1=1.57 D, D2=1.48 D). The larger molecular dipole moment of D1 can control the interfacial dipoles on the ITO surface, forming a directional dipole field on the ITO surface through self-assembly, increasing the ITO work function from 4.80 eV to 5.51 eV, which is highly matched with the hole transport layer PF8Cz (5.33 eV), with a hole injection barrier of only 0.18 eV. In contrast, the non-spiral D2 has a work function of 5.44 eV and a barrier of 0.11 eV, but D1 has better self-assembly properties, ultimately achieving a lower turn-on voltage (1.61 V), solving the problems of high hole injection barrier and high turn-on voltage in traditional materials, effectively raising the work function and optimizing energy level alignment. The helical configuration induces a more ordered dipole orientation, further enhancing the hole injection capability, which is a structural advantage that the non-spiral D2 does not possess. Therefore, the larger the molecular dipole moment, the stronger the ability to regulate the energy levels of the ITO surface, the smaller the energy loss of holes injected from ITO to HTL, and the lower the turn-on voltage.

[0070] like Figure 3 The diagram shows the water contact angle, AFM morphology, and surface potential distribution of the ITO / D1 / D2 self-assembled substrate of this invention. (a) shows the water contact angle test; (b) shows the AFM morphology and RMS roughness of a 1 μm × 1 μm substrate; and (c) shows the KPFM surface potential distribution and CPD value. Figure 3As shown in (a), ITO / D1 (57.95°), ITO / D2 (46.1°), and pure ITO (45.7°) exhibit different surface velocities. D1 significantly enhances the hydrophobicity of the ITO surface, inhibiting moisture adsorption and penetration, thus fundamentally addressing the fatal defect of PEDOT:PSS hygroscopic corrosion of ITO; it also improves the spreadability of the upper PF8Cz film, resulting in denser interfacial contact. Figure 3 From (b), we know that ITO / D1 RMS = 3.66 nm, ITO / D2 = 4.13 nm, and pure ITO = 6.27 nm. The D1 assembly film has the best surface smoothness and fewest defects; low roughness facilitates uniform deposition of subsequent functional layers, reduces interface pinholes and leakage current, reduces carrier scattering, and improves the device's photoelectric conversion efficiency. Figure 3 As shown in (c), ITO / D1 CPD = −591.5 mV, ITO / D2 = −554.2 mV, and ITO = −531.9 mV. D1 has the lowest contact potential difference, corresponding to a deeper Fermi level and a higher work function, which is completely consistent with the UPS test results; the uniform surface potential enables stable hole transport at the interface, avoiding aging degradation caused by local electric field concentration.

[0071] Comprehensive analysis Figure 2 and Figure 3 It is evident that the D1 self-assembled film is denser and more hydrophobic. XPS testing shows that D1 forms stable In-OP bonds with the ITO surface, effectively passivating ITO surface defects and reducing carrier leakage. Reverse JV characteristics show that the leakage current of the D1-based device is much lower than that of PEDOT:PSS and D2-based devices, solving the problems of numerous defects and large leakage current in traditional material films. Therefore, the steric hindrance of the helical molecules inhibits excessive molecular aggregation, achieving ordered self-assembly and forming a dense film with no pinholes and low defects. At the same time, the covalent bonding between the phosphonic acid groups and ITO enhances interfacial stability and reduces carrier recombination and leakage.

[0072] like Figure 9 As shown, the present invention obtains the HOMO / LUMO energy level diagrams of D1 and D2 by DFT calculation, where (a) is D1 and (b) is D2.

[0073] like Figure 10 The TGA curves of D1 and (red) D2 of this invention are shown. The decomposition temperatures of D1 and D2 are 247℃ and 194℃, respectively.

[0074] like Figure 11 As shown, the corresponding atomic force microscope (AFM) cross-sectional profile of the present invention is shown, where (a) is ITO / D1; and (b) is ITO / D2.

[0075] Experiment 2: Fabrication and Performance Testing of QLED Devices 1. Device fabrication The following structure is used: ITO / SAM (D1 / D2 / PEDOT:PSS) / PF8Cz (HTL, 20 nm) / CdSe / ZnS quantum dot emitting layer (QDs, 30 nm) / ZnMgO (ETL, 40 nm) / Al (cathode, 100 nm). Specific steps are as follows: (1) On ITO / D1 self-assembled substrate and ITO / D2 self-assembled substrate, spin-coat 8 mg / mL of chlorobenzene solution of PF8Cz (poly(9,9-dioctylfluorene-alt-carbazole)) at 3000 rpm and anneal at 150 °C for 30 min. (2) Spin-coat quantum dots in an octane solution (15 mg / mL) at 2000 rpm and anneal at 100℃ for 15 min; (3) Spin-coat an ethanol solution of ZnMgO (30 mg / mL) at 3000 rpm and anneal at 80℃ for 15 min; (4) Vacuum thermal evaporation of Al cathode, evaporation rate 0.1 nm / s, thickness 100 nm; (5) After the device is packaged, its optoelectronic performance is tested.

[0076] like Figure 4 As shown, the QLED device structure, light-emitting photographs, and related test curves of the device's photoelectric performance are presented in this invention. (a) is a schematic diagram of the QLED device structure; (b) are actual light-emitting photographs of D1 and D2-based QLEDs; (c) is the JVL current density-voltage-brightness curve; (d) is the EQE-J external quantum efficiency curve; (e) is the CE-J current efficiency curve; (f) is the reverse JV characteristic; (g) is the device lifetime T95; and (h) is the thin film transmittance. Figure 4 As shown in (a), the standard ITO / SAM (D1 / D2) / PF8Cz / QDs / ZnMgO / Al stacked structure, with spiro-ring SAM replacing PEDOT:PSS as the hole injection layer, constructs an acid-free, low-hygroscopic, and highly stable device system, structurally avoiding the inherent drawbacks of traditional HIL materials. Figure 4 As shown in (b), the device exhibits uniform red light emission under the driving voltage, proving that the SAM-modified device has good light emission uniformity, no bright or dark spots, few interface defects, and uniform charge injection, thus meeting the requirements of display applications. Figure 4 From (c), we know that the luminance of D1 at 8V is 240500 cd / m². 2 D2 168100 cd / m 2 PEDOT:PSS only 85900 cd / m 2D1 exhibits optimal energy level matching and interface bonding, resulting in significantly improved hole injection efficiency and optimal charge balance; its brightness far exceeds that of the control group at the same voltage, demonstrating a significant improvement in driving efficiency. Figure 4 From (d), we can see that: D1 peak EQE = 26.58%, D2 = 24.61%, and PEDOT:PSS = 20.23%. The spiro-ring D1 reduces the injection barrier, decreases defect recombination, optimizes charge balance, and significantly increases the radiative recombination rate, resulting in an EQE 31.39% higher than PEDOT:PSS, reaching the current top level for bipolar devices. Figure 4 As shown in (e), D1 has a current efficiency of 27.58 cd / A, significantly higher than D2 (25.0 cd / A) and PEDOT:PSS (20.21 cd / A). This results in lower leakage current, more efficient carrier utilization, higher output luminous intensity per unit current, and lower device power consumption. Figure 4 As shown in (f), the current density of SAM-based devices is greater than that of PEDOT:PSS, with D1 being the largest. D1 exhibits strong interface bonding and energy level modulation, resulting in strong forward conduction capability, good reverse leakage current suppression, superior rectification characteristics, and better device electrical stability. Figure 4 From (g), we know that D1 T95 = 68 h, D2 = 35 h, and PEDOT:PSS = 28 h. Spiral ring SAM is non-acidic, non-hygroscopic, and does not corrode ITO; it also passivates interface defects, inhibits charge accumulation and non-radiative recombination, and delays device aging and degradation. Figure 4 As shown in (h), D1 and D2 have significantly higher transmittance than PEDOT:PSS. The high-transparency SAM film reduces light absorption loss, improves light extraction efficiency, and further enhances device brightness and efficiency.

[0077] Table 1. Comparison of photoelectric performance of D1, D2 and PEDOT:PSS-based QLED devices of the present invention. As shown in Table 1, the start-up voltages for the three materials are close (1.61~1.69 V), indicating that the SAM material can achieve effective hole injection at low voltage without increasing drive power consumption; the maximum brightness is D1240500 cd / m². 2It is 2.80 times that of PEDOT:PSS, breaking through the brightness bottleneck of traditional HIL; the external quantum efficiency EQE:D1 is 31.3% higher than PEDOT:PSS, reaching 26.58%. In terms of efficiency indicators, CE and EQE both show a gradient of D1 > D2 > PEDOT:PSS, confirming the synergistic advantages of the spiro-ring configuration, high dipole moment, and strong interfacial bonding; in terms of lifetime, D1 T95 68 h is 142.86% higher than PEDOT:PSS 28 h, perfectly matching the data of Instruction 5; in terms of transmittance, the transmittance of D1 and D2 films is significantly higher than that of PEDOT:PSS, indicating higher light extraction efficiency; in terms of leakage current, SAM-based devices have higher forward current and lower reverse leakage current, resulting in better electrical stability. Therefore, overall, it is proven that spiro-ring self-assembled SAM is the preferred material for high-performance, long-lifetime hole injection layers to replace PEDOT:PSS.

[0078] Combined with Table 1 Figure 4 Data analysis reveals that the helical configuration of D1 achieves synergistic optimization of dipole moment, film formation, and energy level matching, significantly improving hole injection efficiency and carrier balance, reducing exciton quenching, while the dense self-assembled thin film blocks moisture and electrode corrosion, significantly extending device lifetime. The overall performance of D1-based QLEDs is comprehensively superior: maximum brightness reaches 240,500 cd / m². 2 It is a PEDOT:PSS-based device (85900 cd / m²). 2 It is 2.8 times that of PEDOT:PSS (20.23%); the external quantum efficiency (EQE) reaches 26.58%, an improvement of 31.4% compared to PEDOT:PSS (20.23%); the current efficiency (CE) reaches 27.58 cd / A, an improvement of 36.5% compared to PEDOT:PSS (20.21 cd / A); T 95 Working life up to 68 hours (@19600 cd / m³) 2 The transmittance of D1 film is 142.8% higher than that of PEDOT:PSS (28 h) and 94.3% higher than that of D2 (35 h). The transmittance of D1 film in the visible light region (480~840 nm) is over 98%, which is significantly higher than that of PEDOT:PSS. It will not affect the light output of the device and is suitable for the application requirements of high-performance display devices.

[0079] like Figure 12 The normalized EL spectrum of the QLED device based on D1 and D2 is shown in the figure.

[0080] like Figure 13 As shown, this invention presents the energy band diagram of a quantum dot light-emitting diode (QLED) based on D1, D2, and PEDOT:PSS.

[0081] Table 2 Optical and electrochemical properties of D1 and D2 A comprehensive analysis of Table 2 and the above results reveals that this invention, through spirocyclic molecular structure design and self-assembly interface engineering, achieves a more fundamental and comprehensive mechanism for improving lifetime. The T95 (brightness decay to 95%) is: D1 = 68 h, PEDOT:PSS = 28 h; D1's T50 is as high as 1286 h; the rigid spirocyclic configuration of D1 exhibits higher thermal stability (Td = 247 ℃), a deeper work function, and high thermal stability, ensuring that the molecular framework does not decompose or the configuration does not collapse under high-temperature operation; D1 forms a strong PO-In covalent bond with ITO, passivating oxygen vacancies and inhibiting ITO corrosion, thus completely solving the PEDOT:PSS problem. It addresses issues such as acid corrosion and moisture aging; it features a larger dipole moment and optimal energy level matching, achieving precise charge balance, reducing interfacial charge accumulation and non-radiative recombination, and physically delaying the aging of the light-emitting layer and interfacial layer; it also has a D1 low-roughness, highly hydrophobic thin film that blocks the intrusion of water vapor and oxygen molecules, reducing the device degradation rate and fundamentally improving device stability; and spirocyclic acridine-based SAM is a new high-performance, long-lifetime, high-transmittance hole injection layer material for QLEDs that can replace PEDOT:PSS.

[0082] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A compound for assembling a hole injection layer material, characterized in that, This compound comprises compounds with the structure shown in formula (I): In equation (Ⅰ), n is an integer from 1 to 10.

2. The compound according to claim 1, characterized in that, The compound comprises compounds with structures as shown in formulas (II) and (III): In equations (II) and (III), n is an integer from 1 to 8.

3. The compound according to claim 2, characterized in that, The n is 4; the molecular dipole moment of the compound with the structure shown in formula (II) is ≥1.4 D; the molecular dipole moment of the compound with the structure shown in formula (III) is ≥1.5 D.

4. A method for preparing the compound according to any one of claims 1 to 3, characterized in that, The method includes: (1) Under the protection of an inert gas, acridine compounds, anhydrous aprotic polar organic solvent and NaH were mixed and stirred, and bromoalkane was added to carry out N-nucleophilic substitution reaction. The mixture was cooled, quenched, extracted, dried, concentrated by rotary evaporation, and purified by column chromatography to obtain intermediate 1. (2) Intermediate 1 was mixed with phosphite and subjected to Arbuzov reaction at 140 °C. The mixture was then distilled under reduced pressure to obtain intermediate 2. (3) Dissolve intermediate 2 in anhydrous chlorinated hydrocarbon, add bromosilane and stir to carry out ester decomposition reaction, remove solvent by vacuum evaporation, add methanol and reflux reaction; concentrate by rotary evaporation, recrystallize and dry under vacuum.

5. The preparation method according to claim 4, characterized in that, The acridine compounds include spiro[acridine-fluorene] compounds and dihydroacridine compounds; the anhydrous aprotic polar organic solvent is N,N-dimethylformamide.

6. The preparation method according to claim 5, characterized in that, The spiro[acridin-fluorene] compound is 10H-spiro[acridin-9,9'-fluorene]; the dihydroacridin compound is 9,9-diphenyl-9,10-dihydroacridin.

7. The preparation method according to claim 4, characterized in that, The phosphite is triethyl phosphite, the chlorinated hydrocarbon is dichloromethane, the bromosilane is trimethylbromosilane, and the bromoalkane is 1,4-dibromobutane.

8. The preparation method according to claim 4, characterized in that, The molar ratio of the acridine compound, NaH, and bromoalkane is 1:(1~1.5):(1~2); the molar ratio of intermediate 1 to phosphite is 1:(15~25); and the molar ratio of intermediate 2 to bromosilane is 1:(2~4).

9. The use of a compound as described in any one of claims 1 to 3 in the fabrication of quantum dot light-emitting diodes.

10. The application according to claim 9, characterized in that, The quantum dot light-emitting diode device adopts a positive-mounted structure and includes: indium tin oxide, a self-assembled monolayer, a hole injection layer, a quantum dot light-emitting layer, a zinc magnesium oxide alloy layer, and aluminum; The raw material for preparing the self-assembled monolayer comprises a compound with the structure shown in formula (I) as described in claim 1; The raw material for preparing the hole injection layer includes poly(9,9-dioctylfluorene-alt-carbazole); The aluminum is used as the cathode.

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