Flexible electroluminescent line and hole injection material

Abstract

The present application relates to the field of semiconductor light source and organic photoelectric material, and particularly relates to a flexible electroluminescent wire and a hole injection material. The hole injection material introduces phosphoric acid groups and conjugated main chain structures in a molecular skeleton, can form stable combination with the anode surface through hydrogen bond or coordination, and improves the interface adhesion. Meanwhile, the hole injection barrier is reduced by adjusting the work function, so as to improve the hole injection efficiency and reduce the device starting voltage. In addition, the high conjugation of the polymer main chain and the design of the flexible side chain endow the material with excellent mechanical flexibility, so that the life and reliability of the coaxial flexible OLED light-emitting wire are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor light sources and organic optoelectronic materials, and in particular to a flexible electroluminescent wire and a hole injection material. BACKGROUND

[0002] OLED (organic light-emitting diode) has advantages of self-emission, high contrast, wide viewing angle, fast response speed, flexible display, etc., and has shown great potential in the fields of display and lighting. However, the current market applications of OLED are mainly concentrated in flat display and large-area lighting, and there are relatively few studies on light-emitting wire lighting products with special forms and application scenarios.

[0003] With the rapid development of emerging fields such as wearable electronics, smart textiles, and flexible decorative lighting, there is an increasing demand for slender, bendable, and weavable light-emitting devices that can achieve multi-color and uniform light emission. Compared with traditional rigid display and lighting elements, light-emitting devices can be more flexibly integrated into clothing, medical patches, architectural decorations, and portable devices, thereby broadening the application scenarios.

[0004] Organic light-emitting diodes (OLEDs) have been widely used in flat panel displays and lighting panels due to their advantages of self-emission, high contrast, wide viewing angle, low voltage direct current driving, flexibility, and adjustable light-emitting wavelength. In recent years, researchers have begun to attempt to apply OLEDs to fibers or coaxial structures in order to obtain a line-shaped display element with 360° light emission and high flexibility. By using methods such as thermal evaporation, dip coating, and spray coating, OLED multi-layer structures can be deposited on cylindrical substrates, thereby realizing wearable and weavable flexible light-emitting fibers. However, this type of technology still faces several key challenges:

[0005] Limitations of hole injection layer (HIL) materials: The commonly used HIL materials such as PEDOT:PSS, MoO3, and CuPc have limited adhesion on the surface of cylindrical or coaxial anodes, a small range of work function adjustment, and insufficient stability under high humidity, high temperature, and repeated bending conditions, which can easily lead to a shortened device life.

[0006] Insufficient mechanical stability: The traditional HIL layer deposited on the coaxial curved surface is prone to micro-cracks or peeling due to mechanical stress, which affects the hole injection efficiency and light emission uniformity.

[0007] Energy level matching problem: The large difference between the traditional HIL and the anode work function results in a high hole injection barrier, a high device start voltage, and a reduced driving efficiency.

[0008] Poor compatibility for large-scale manufacturing: Some high-performance HIL materials are limited in solution processing and roll-to-roll continuous preparation, which cannot meet the requirements of industrial production.

[0009] To improve the above problems, researchers try to introduce crosslinking agent or hydrophobic modification in PEDOT:PSS to improve the hygrothermal stability, or use inorganic materials (such as NiO X ) to replace HIL to improve the interface energy level matching and chemical stability. But these methods have their own shortcomings: inorganic HIL is usually brittle, it is difficult to deal with the repeated bending of coaxial fiber structure; although the organic HIL such as 2-(3,6-dimethyl-9H-carbazole-9-yl) ethyl phosphonic acid has good flexibility, but the adhesion and stability still cannot meet the needs of long-term use in wearable environment. SUMMARY

[0010] In view of the problems of the existing hole injection layer (HIL) material in the coaxial flexible OLED light-emitting wire, such as interface adhesion, energy level matching, mechanical stability and environmental resistance, the present application proposes to use a phosphonic acid-based polymer with the structure shown in the general formula as a hole injection layer in the OLED device with coaxial structure.

[0011] The technical scheme of the present application is realized by the following way: a flexible electroluminescent wire is provided, which comprises a flexible conductive core wire and an OLED layer wrapped outside the conductive core wire; the OLED layer comprises an anode, a hole transport layer, and a hole injection layer between the anode and the hole transport layer, and the material structure of the hole injection layer is as follows:

[0012]

[0013] Wherein, X is S, O, Se or N-R, R is an alkyl or aryl substituent;

[0014] Ar is an aromatic ring or heteroaromatic ring;

[0015] n is a natural number, n = 1 ~ 100; y is an integer greater than or equal to 0.

[0016] In a preferred embodiment of the present application, the OLED light-emitting layer comprises an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode arranged in sequence.

[0017] In a preferred embodiment of the present application, it further comprises a transparent encapsulation layer wrapped outside the OLED light-emitting layer.

[0018] On the other hand, the present application also provides a hole injection material, Ar is selected from the following:

[0019]

[0020] Wherein, R' is selected from H, alkyl, alkoxy, oligoether group.

[0021] In a preferred embodiment of the present application, the molecular structure of the hole injection material is selected from the following:

[0022]

[0023] .

[0024] The beneficial effects are as follows:

[0025] The phosphoric acid-based polymer of the present application introduces phosphoric acid groups and conjugated main chain structures into the molecular skeleton, can form stable binding with the surface of an anode (such as ITO, graphene, carbon nanotubes, etc.) through hydrogen bonding or coordination, improve the interfacial adhesion; at the same time, by adjusting the work function, the hole injection barrier is reduced, thereby improving the hole injection efficiency and reducing the device start-up voltage. In addition, the high conjugation of the polymer main chain and the design of flexible side chains endow the material with excellent mechanical flexibility and hygrothermal stability, adapt to the roll-to-roll solution processing technology, and are suitable for industrialized continuous production.

[0026] Through the above scheme, the coaxial flexible OLED light emitting line of the present application realizes 360° annular uniform light emission, low-voltage high-efficiency driving, long service life and high reliability, and is especially suitable for wearable devices, smart textiles, medical patches and decorative lighting fields. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The structure schematic diagram of a preferred embodiment of the flexible electroluminescent line of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely in combination with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] The present application will be further described in detail below in combination with the drawings and embodiments.

[0030] The synthesis general formula of the hole injection polymer material of the present application is as follows:

[0031]

[0032] The steps include:

[0033] Alkylation reaction: Carbonazole compound (II-1) was dissolved in dry dimethyl sulfoxide (DMSO) under nitrogen protection, and sodium hydride (NaH) was slowly added. After stirring to complete the reaction, sodium carbazolide anion was generated. Then bromophosphonate compound [II-2, such as diethyl (3-bromopropyl) phosphonate] dissolved in DMSO was added dropwise, and the reaction was carried out at 60°C for 20 hours. After the reaction was completed, it was poured into water, extracted with ethyl acetate, washed with saturated brine, and the organic phase was dried and the solvent was removed under reduced pressure. After silica gel column chromatography, the alkylation product (II-3) was obtained.

[0034] Bromination reaction (NBS bromination): The alkylation product (II-3) was dissolved in a suitable solvent (such as carbon tetrachloride, dichloromethane), N-bromosuccinimide (NBS) and an appropriate initiator were added, and the reaction was carried out under inert atmosphere to introduce bromine atoms as reaction sites for subsequent Suzuki coupling (II-4).

[0035] Suzuki coupling reaction: The bromination product (II-4) was reacted with an aryl borate-containing conjugated monomer (II-5) in the presence of a palladium catalyst (such as Pd(PPh3)4) and a base (such as K2CO3) in a mixed solvent (water / ethanol / tetrahydrofuran) at reflux to form a polymer backbone containing a conjugated main chain and phosphonate side chains (II-6).

[0036] Phosphonate hydrolysis reaction: The obtained polymer (II-6) was dissolved in dichloromethane (CH2Cl2), and trimethylsilyl bromide (BrSiMe3) was added. After stirring at room temperature for 12 hours, methanol was added and stirred for 12 hours to hydrolyze the phosphonate to partially or completely convert it to phosphoric acid groups. Finally, the reaction solution was concentrated, and the product was precipitated by dropping into ether. After multiple precipitation purifications, the target phosphoric acid group-containing polymer (T) was obtained.

[0037] Figure 1 The structure of a preferred embodiment of the flexible electroluminescent wire of the present application is shown. The device structure includes, from the inside out:

[0038] Conductive core wire (01): As the center electrode of the device, materials with good conductivity and flexibility are selected, such as metal filaments (copper, silver), alloy wires, carbon nanotube bundles, graphene fibers, etc. The core wire diameter can be selected in the range of 10-50 μm according to application requirements.

[0039] Insulating isolation layer (02): coated on the outer surface of the conductive core wire, used to achieve electrical isolation and provide a flat deposition interface. The material can be a heat-resistant flexible insulating film such as polyimide (PI) or polyethylene terephthalate (PET), with a thickness of 5-20 μm.

[0040] Anode (03): Deposited on the surface of the insulating isolation layer, used for injecting holes. Indium tin oxide (ITO), fluorine-doped tin oxide (FTO), silver nanowire transparent conductive film, carbon nanotube conductive layer, etc. can be selected. Thickness 50-100 nm.

[0041] Hole injection layer (HIL, 04): The phosphoric acid-based polymer material of the application is used, the phosphoric acid group enhances the adhesion to the surface of the anode through hydrogen bonding or coordination, and adjusts the work function of the anode to optimize the energy level matching. The thickness of this layer is generally 5-20 nm, which can be prepared by solution coating or inkjet printing.

[0042] Hole transport layer (HTL, 05): Located outside the hole injection layer, used for efficient transport of holes to the light-emitting layer. TPD, NPB or other high hole mobility organic semiconductor materials can be used. Thickness 30-50 nm.

[0043] Light-emitting layer (EML, 06): The core of the device for emitting light, which can be used according to the needs of small molecule evaporation type or polymer solution processing type material, the light-emitting color can be adjusted by doping system to realize single color, multi-color or near white light output. Thickness 20-40 nm.

[0044] Electron transport layer (ETL, 07): Used for transporting electrons and blocking holes, materials such as Alq3, TPBi, ZnO nanoparticles, etc. can be selected. Thickness 25-35 nm.

[0045] Electron injection layer (EIL, 08): Located between the outer cathode layer and the electron transport layer, it reduces the electron injection barrier, and the material can be LiF, Cs2CO3, etc. Thickness 0.3-0.7 nm.

[0046] Cathode (09): Used as an electron injection electrode, metal thin films such as aluminum, silver, magnesium-silver alloy, etc. can be selected. Thickness 10-50 nm.

[0047] Flexible transparent encapsulation layer (10): As the outermost protective structure, the material can be a flexible barrier film or a high-transparency polymer, which prevents water and oxygen from entering and protects the device from mechanical damage, and can add microcapsule self-repairing function according to needs. Thickness 10-50 μm.

[0048] In another embodiment of the application, the reverse structure has a cathode inside and an anode outside, and the order of the other layers is changed in sequence except for the insulating isolation layer (02) and the flexible transparent encapsulation layer (10).

[0049] Example 1: Synthesis of a representative hole injection material 1a:

[0050]

[0051] Thiophene carbazole (A-1-1, 179.26 g, 1 mol) was dissolved in 1 L of anhydrous DMSO under nitrogen protection, and 10 equivalents of NaH (60% dispersion, 400 g, NaH 240 g, 10 mol) was added to form a sodium carbazole salt. Then diethyl (3-bromopropyl) phosphonate (A-1-2, 259.08 g, 1 mol) was dissolved in DMSO and added dropwise to the reaction solution, and the reaction was stirred at 60 ℃ for 20 h. After the reaction was completed, it was poured into water, extracted with ethyl acetate, washed with saturated brine, dried with anhydrous MgSO4, and the solvent was removed under reduced pressure. Purification by silica gel column chromatography (petroleum ether: ethyl acetate = 2:1) gave the alkylated product A-1-3, about 319 g, yield 85%. 1 H NMR (500 MHz, Chloroform ) δ 7.46 (d, J = 14.8 Hz,2H), 7.31 (d, J = 15.0 Hz, 2H), 4.16 (t, J = 9.9 Hz, 2H), 4.01 (q, J = 11.8 Hz,4H), 2.36 (td, J = 11.3, 1.0 Hz, 2H), 2.25 – 1.95 (m, 2H), 1.07 (t, J = 11.8 Hz,6H).

[0052] The alkylated product A-1-3 (187.71 g, 0.50 mol) was dissolved in 1.0 L of chloroform under nitrogen protection, and stirred to completely dissolve; N-bromosuccinimide (NBS) (195.79 g, 1.10 mol, 2.2 eq) was prepared into a chloroform slurry (about 500 mL). The reaction solution was cooled to 0-5 ℃, and the NBS slurry was added slowly in batches (control temperature rise). After the addition was completed, it was raised to the reflux temperature of chloroform, and stirred in the dark or weak light for 6 h under inert atmosphere. The reaction solution was cooled to room temperature, and the by-product succinimide solid was removed by filtration, and the filter cake was washed with a small amount of chloroform and the wash was combined. The combined organic phase was washed with 5% Na2S2O3 solution (to remove free bromine), saturated NaHCO3 solution (to neutralize the acid), and saturated brine, dried with anhydrous MgSO4, filtered, and the solvent was removed under reduced pressure. Purification by silica gel column chromatography (petroleum ether / ethyl acetate ≈ 8:1 → 4:1 gradient) gave the brominated product A-1-4, yield about 208.66 g, yield 81%. 1H NMR (500 MHz, Chloroform ) δ 7.63 (s, 2H), 4.16 (t, J = 10.6 Hz, 2H), 4.01 (q, J = 11.8 Hz,4H), 2.49 – 2.21 (m, 2H), 2.21 – 1.90 (m, 2H), 1.07 (t, J = 11.8 Hz, 6H).

[0053] A-1-4 (5.15 g, 10.0 mmol) and A-1-5 (diboronate) (5.58 g, 10.0 mmol) were weighed into a dry three-necked flask under nitrogen protection, and anhydrous toluene 150 mL was added to disperse / dissolve; 2 M aqueous K2CO3 solution 15 mL (30.0 mmol, 3.0 eq) was added to form a toluene / water biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. The system was degassed by vacuum / nitrogen three times, and then the reaction was stirred at toluene reflux (about 110°C) for 12 hours. After the reaction was completed, the reaction solution was slowly poured into a large amount of methanol, and the polymer solid was stirred to precipitate. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, then washed with deionized water until neutral, and placed in a vacuum dryer at 40-50°C. The dried solid was subjected to Soxhlet extraction, and the solvents were in the order of: methanol → acetone → n-hexane → chloroform. The chloroform extract layer was collected and concentrated under reduced pressure to obtain the target polymer A-1-6 as a light-colored solid. 1 H NMR (500MHz, Chloroform ) δ 7.53 (s, 1H), 7.43 (s, 1H), 7.25 (s, 1H), 7.23 (s, 1H),4.21 – 3.85 (m, 10H), 2.44 – 2.26 (m, 2H), 2.20 – 2.02 (m, 2H), 1.95 – 1.68(m, 4H), 1.50 – 1.32 (m, 4H), 1.31 – 1.16 (m, 12H), 1.06 m, 6H), 0.94 – 0.79(m, 6H).

[0054] Polymer A-1-6 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and the mixture was stirred at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and the stirring was continued at room temperature for 12 h. After the reaction was completed, the mixture was concentrated under reduced pressure, and the obtained viscous solution was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times. The precipitate was filtered to obtain a pale yellow powder of the phosphonic acid group-containing polymer 1a. 1 H NMR (500 MHz, Chloroform ) δ 7.60(s, 1H), 7.47 (s, 1H), 7.28 (s, 1H), 7.18 (s, 1H), 4.13 (m, 6H), 2.48 – 2.23(m, 2H), 2.10 – 1.95 (m, 2H), 1.80 (m, 4H), 1.53 – 1.06 (m, 17H), 1.01 – 0.69(m, 6H).

[0055] Example 2: Synthesis of a representative hole injection material 2a:

[0056]

[0057] Under nitrogen protection, A-1-4 (5.15 g, 10.0 mmol) and A-2-1 (diboronate) (5.51 g, 10.0 mmol) were weighed into a dry three-necked flask, and anhydrous toluene 150 mL was added to disperse / dissolve them; 2 M aqueous K2CO3 solution 15 mL (30.0 mmol, 3.0 eq) was added to form a toluene / water two-phase system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were sequentially added as phase transfer catalysts. After the system was degassed by three times of vacuum / nitrogen, the reaction was stirred at toluene reflux (≈110 ℃) for 12 hours.

[0058] After the reaction was completed, the reaction solution was slowly poured into a large amount of methanol, and the polymer solid was precipitated by stirring. The obtained solid was collected by filtration, washed with a dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, washed with deionized water until neutral, and dried in a vacuum at 40-50 ℃. The dried solid was subjected to Soxhlet extraction, and the solvents were sequentially anhydrous methanol, anhydrous acetone, n-hexane, and chloroform. The chloroform extract was collected and concentrated under reduced pressure to obtain the target polymer A-2-2 as a light-colored solid. 1H NMR (500 MHz, Chloroform ) δ 8.16 (s, 1H), 7.88 (s, 1H), 7.28 (s,2H), 4.41 – 3.07 (m, 28H), 2.36 (td, J = 11.0, 1.0 Hz, 2H), 2.24 – 1.97 (m,2H), 1.07 (m, 6H).

[0059] Polymer A-2-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirring was continued at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for another 12 h. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and the resulting viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times. The precipitate was filtered to obtain a yellowish powder of phosphonic acid-based polymer 2a. 1 H NMR (500 MHz, Chloroform ) δ 8.09(s, 1H), 7.87 (s, 1H), 7.31 (s, 1H), 7.29 (s, 1H), 4.44 – 3.09 (m, 24H), 2.52– 2.23 (m, 2H), 2.20 – 1.81 (m, 2H).

[0060] Example 3: Synthesis of a representative hole injection material 3a:

[0061]

[0062] Under nitrogen, A-1-4 (5.15 g, 10.0 mmol) and A-3-1 (diboronate) (3.80 g, 10.0 mmol) were weighed into a dry three-necked flask and dissolved in 150 mL of anhydrous toluene. 15 mL (30.0 mmol, 3.0 eq) of a 2 M aqueous solution of K2CO3 was added to form a toluene / aqueous biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. The system was degassed by three cycles of vacuum / nitrogen and the reaction was stirred at toluene reflux (~ 110 °C) for 12 h. After cooling to room temperature, the reaction was slowly poured into a large excess of methanol and the polymer precipitated. The resulting solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligand / base, then with deionized water until neutral, and dried under vacuum at 40-50 °C. The dried solid was subjected to Soxhlet extraction with solvents in the following order: methanol -> acetone -> n-hexane -> chloroform. The chloroform extract was collected and concentrated under reduced pressure to give the target polymer A-3-2 as a light-colored solid. 1 H NMR (500 MHz, Chloroform ) δ 8.46 (t, J = 2.9 Hz, 1H), 8.12 – 7.44 (m, 7H), 4.35 – 3.76(m, 6H), 2.36 (td, J = 11.7, 1.0 Hz, 2H), 2.21 – 1.83 (m, 2H), 1.07 (m, 6H).

[0063] Polymer A-3-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL) and excess trimethylsilyl bromide (TMSBr, 2.00 g) was added. The mixture was stirred at room temperature for 12 h. Anhydrous methanol (20 mL) was then added and stirring was continued at room temperature for another 12 h. After the reaction was completed, the mixture was concentrated under reduced pressure and the resulting viscous liquid was slowly added dropwise to a large excess of anhydrous diethyl ether (200 mL) to precipitate the polymer. The precipitation was repeated three times and the polymer was collected by filtration as a light yellow powder. 1 H NMR (500 MHz, Chloroform ) δ 8.45(t, J = 3.0 Hz, 1H), 8.05 – 7.42 (m, 7H), 4.15 (t, J = 10.6 Hz, 2H), 2.34 (dd, J= 16.9, 5.7 Hz, 2H), 2.16 – 1.74 (m, 2H).

[0064] Example 4: Synthesis of representative hole injection material 4a:

[0065]

[0066] A-1-4 (5.15 g, 10.0 mmol) and A-4-1 (diboronate) (6.42 g, 10.0 mmol) were weighed into a dry three-necked flask under nitrogen protection, and anhydrous toluene 150 mL was added to disperse / dissolve; 15 mL (30.0 mmol, 3.0 eq) of a 2 M aqueous solution of K2CO3 was added to form a toluene / water biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. After three times of vacuum / nitrogen degassing, the system was stirred at toluene reflux (≈110 °C) for 12 hours. After the reaction was completed, the reaction solution was slowly poured into a large amount of methanol, and the polymer solid was stirred to precipitate. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, then washed with deionized water until neutral, and placed in a vacuum dryer at 40-50 °C. The dried solid was subjected to Soxhlet extraction, and the solvents were in the order of: methanol → acetone → n-hexane → chloroform. The chloroform extract layer was collected and concentrated under reduced pressure to obtain the target polymer A-4-2 as a light-colored solid. 1 H NMR (500MHz, Chloroform ) δ 8.07 (d, J = 15.5 Hz, 1H), 7.79 (ddd, J = 33.5, 11.1, 9.0 Hz,3H), 7.42 (s, 1H), 7.31 (d, J = 2.9 Hz, 1H), 7.20 (dd, J = 14.9, 3.0 Hz, 1H),7.08 (s, 1H), 4.42 – 3.58 (m, 6H), 2.51 – 1.75 (m, 8H), 1.58 – 0.71 (m, 37H).

[0067] Polymer A-4-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirring was continued at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for another 12 h. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and the resulting viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times. The precipitate was filtered to obtain a phosphonic acid-based polymer 4a as a light yellow powder. 1 H NMR (500 MHz, Chloroform ) δ 8.09(d, J = 14.7 Hz, 1H), 7.90 (d, J = 14.9 Hz, 1H), 7.79 (dt, J = 14.8, 3.0 Hz, 2H),7.66 (s, 1H), 7.54 (s, 1H), 7.31 (d, J = 3.0 Hz, 1H), 7.22 (dd, J = 15.0, 2.9 Hz,1H), 4.16 (t, J = 15.1 Hz, 2H), 2.42 – 2.25 (m, 2H), 2.18 – 1.74 (m, 6H), 1.52– 1.12 (m, 25H), 1.05 – 0.61 (m, 6H).

[0068] Example 5: Synthesis of a representative hole injection material 5a:

[0069]

[0070] Under nitrogen, A-1-4 (5.15 g, 10.0 mmol) and A-5-1 (diboronate) (5.31 g, 10.0 mmol) were weighed into a dry three-necked flask and dissolved / dispersed in 150 mL of anhydrous toluene; 15 mL (30.0 mmol, 3.0 eq) of a 2 M aqueous solution of K2CO3 was added to form a toluene / aqueous biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) as phase transfer catalyst were added sequentially. The system was degassed by three cycles of vacuum / nitrogen and the reaction was stirred at toluene reflux (~ 110 °C) for 12 h. After cooling to room temperature, the reaction was slowly poured into a large excess of methanol and the polymer precipitated. The resulting solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligand / base, then with deionized water until neutral, and dried under vacuum at 40-50 °C. The dried solid was subjected to Soxhlet extraction with solvents in the following order: methanol -> acetone -> n-hexane -> chloroform, and the chloroform extract was collected and concentrated under reduced pressure to give the target polymer A-5-2 as a light-colored solid. 1 H NMR (500 MHz, Chloroform ) δ 8.46 (t, J = 2.9 Hz, 1H), 8.12 – 7.44 (m, 7H), 4.35 – 3.76(m, 6H), 2.36 (td, J = 11.7, 1.0 Hz, 2H), 2.21 – 1.83 (m, 2H), 1.07 (m, 6H).

[0071] Polymer A-5-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL) and excess trimethylsilyl bromide (TMSBr, 2.00 g) was added and stirred at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added and stirring was continued at room temperature for 12 h. After the reaction was completed, the reaction mixture was concentrated under reduced pressure and the resulting viscous liquid was slowly dropped into a large excess of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times. The resulting light yellow powder was collected by filtration. 1 H NMR (500 MHz, Chloroform ) δ 7.96(dd, J = 14.9, 3.0 Hz, 1H), 7.88 – 7.51 (m, 5H), 7.42 (d, J = 3.1 Hz, 1H), 7.17(dd, J= 15.0, 2.9 Hz, 1H), 4.16 (t, J = 15.0 Hz, 4H), 2.48 – 2.24 (m, 2H), 2.21– 1.94 (m, 2H), 1.92 – 1.61 (m, 2H), 1.54 – 1.08 (m, 11H), 1.04 – 0.64 (m,3H).

[0072] Example 6: Synthesis of representative hole injection material 6a:

[0073]

[0074] A-1-4 (5.15 g, 10.0 mmol) and A-6-1 (diboronate) (5.50 g, 10.0 mmol) were weighed into a dry three-necked flask under nitrogen protection, and anhydrous toluene 150 mL was added to disperse / dissolve; 2 M aqueous K2CO3 solution 15 mL (30.0 mmol, 3.0 eq) was added to form a toluene / water biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. The system was degassed by vacuum / nitrogen three times, and the reaction was stirred at toluene reflux for 12 hours.

[0075] After the reaction was completed, it was cooled to room temperature, and the reaction solution was slowly poured into a large amount of methanol to precipitate the polymer solid. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, and then washed with deionized water until neutral. The solid was dried in vacuum at 40-50 °C. The dried solid was subjected to Soxhlet extraction, and the solvents were in the order of: methanol → acetone → n-hexane → chloroform. The chloroform extract layer was collected and concentrated under reduced pressure to obtain the target polymer A-6-2 as a light-colored solid. 1 H NMR (500 MHz, Chloroform ) δ 8.14 – 7.53 (m, 5H), 7.47 (d, J = 3.1Hz, 1H), 7.16 (dd, J = 15.0, 2.9 Hz, 1H), 7.04 (s, 1H), 4.80 – 3.24 (m, 15H),2.49 – 1.91 (m, 4H), 1.10 (m, 9H).

[0076] Polymer A-6-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirring was performed at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for 12 h. After the reaction was completed, the reaction solution was concentrated under reduced pressure, and the obtained viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times, and the polymer was collected by filtration to obtain a light yellow powder of the phosphonic acid group-containing polymer 6a. 1 H NMR (500 MHz, Chloroform ) δ 8.13 –7.54 (m, 5H), 7.45 (d, J = 3.1 Hz, 1H), 7.25 – 6.80 (m, 2H), 4.30 (dt, J = 30.2,14.7 Hz, 4H), 3.86 – 3.30 (m, 8H), 2.35 (dd, J = 16.7, 5.7 Hz, 2H), 2.18 – 1.75(m, 2H), 1.13 (t, J = 11.8 Hz, 3H).

[0077] Example 7: Synthesis of a representative hole injection material 7a:

[0078]

[0079] Under nitrogen protection, A-1-4 (5.15 g, 10.0 mmol) and A-7-1 (diboronate) (6.70 g, 10.0 mmol) were weighed into a dry three-necked flask, anhydrous toluene 150 mL was added to disperse / dissolve; 2 M aqueous K2CO3 solution 15 mL (30.0 mmol, 3.0 eq) was added to form a toluene / water two-phase system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were sequentially added as phase transfer catalysts. After three times of vacuum-nitrogen degassing, the system was stirred at toluene reflux (about 110°C) for 12 hours. After the reaction was completed, the reaction solution was slowly poured into a large amount of methanol to precipitate the polymer solid. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, and then washed with deionized water until neutral. The solid was dried at 40-50°C under vacuum. The dried solid was subjected to Soxhlet extraction, and the solvents were sequentially anhydrous methanol, acetone, n-hexane and chloroform. The chloroform extract was collected and concentrated under reduced pressure to obtain the target polymer A-7-2 as a light-colored solid.1 H NMR (500 MHz, Chloroform ) δ 8.33 (s, 1H), 7.83 (s, 1H), 7.73 (s, 1H), 6.99 (s, 1H),4.59 – 3.69 (m, 10H), 2.60 – 2.25 (m, 2H), 2.11 (pd, J = 11.4, 0.9 Hz, 2H),1.91 – 1.63 (m, 4H), 1.58 – 0.64 (m, 28H).

[0080] Polymer A-7-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirring was continued at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for another 12 h. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and the resulting viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times. The precipitate was filtered to obtain a pale yellow powder of phosphonic acid-based polymer 7a. 1 H NMR (500 MHz, Chloroform ) δ 8.35(s, 1H), 7.86 (s, 1H), 7.78 (s, 1H), 7.74 (s, 1H), 4.14 (dt, J = 24.9, 15.0 Hz,6H), 2.58 – 0.64 (m, 31H).

[0081] Example 8: Synthesis of a representative hole injection material 8a:

[0082]

[0083] Under nitrogen, A-1-4 (5.15 g, 10.0 mmol) and A-8-1 (diboronate) (6.78 g, 10.0 mmol) were weighed into a dry three-necked flask and dissolved in 150 mL of anhydrous toluene. 15 mL (30.0 mmol, 3.0 eq) of a 2 M aqueous solution of K2CO3 was added to form a toluene / aqueous biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. The system was degassed by three cycles of vacuum / nitrogen and the reaction was stirred at toluene reflux (~ 110 °C) for 12 h. After cooling to room temperature, the reaction was slowly poured into a large amount of methanol and the polymer was precipitated by stirring. The resulting solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligand / base, and then washed with deionized water until neutral. The dried solid was subjected to Soxhlet extraction with solvents in the following order: methanol → acetone → n-hexane → chloroform. The chloroform extract was collected and concentrated under reduced pressure to obtain the target polymer A-8-2 as a light-colored solid. 1 H NMR (500 MHz, Chloroform ) δ 8.24 (s, 1H), 7.85 (s, 1H), 7.70 (s, 1H), 7.04 (s, 1H),4.68 – 3.16 (m, 28H), 2.36 (td, J = 10.9, 0.7 Hz, 2H), 2.23 – 1.87 (m, 2H),1.07 (m, 6H).

[0084] The polymer A-8-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), and excess trimethylsilyl bromide (TMSBr, 2.00 g) was added. The mixture was stirred at room temperature for 12 h. Then anhydrous methanol (20 mL) was added, and the stirring was continued at room temperature for another 12 h. After the reaction was completed, the mixture was concentrated under reduced pressure, and the resulting viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) for precipitation. The precipitation was repeated three times, and the light yellow powder of the phosphonic acid-based polymer 8a was obtained by filtration. 1 H NMR (500 MHz, Chloroform ) δ 8.22(s, 1H), 7.85 (s, 1H), 7.68 (s, 1H), 7.04 (s, 1H), 4.24 (dt, J= 30.2, 14.7 Hz,6H), 3.89 – 3.17 (m, 18H), 2.44 – 2.25 (m, 2H), 2.20 – 1.95 (m, 2H).

[0085] Example 9: Synthesis of representative hole injection material 9a:

[0086]

[0087] A-1-4 (5.15 g, 10.0 mmol) and A-9-1 (diboronate) (6.30 g, 10.0 mmol) were weighed into a dry three-necked flask under nitrogen protection, and anhydrous toluene 150 mL was added to disperse / dissolve them; 15 mL (30.0 mmol, 3.0 eq) of a 2 M aqueous K2CO3 solution was added to form a toluene / water biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. After three times of vacuum / nitrogen degassing, the system was stirred at toluene reflux (≈110 ℃) for 12 hours. After the reaction was completed, the reaction solution was slowly poured into a large amount of methanol, and the polymer solid was stirred to precipitate. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, and then washed with deionized water until neutral, and placed in a vacuum dryer at 40-50 ℃. The dried solid was subjected to Soxhlet extraction, and the solvents were in the order of: methanol → acetone → n-hexane → chloroform. The chloroform extract layer was collected and concentrated under reduced pressure to obtain the target polymer A-9-2 as a light-colored solid. 1 H NMR (500MHz, Chloroform ) δ 7.58 (s, 1H), 7.34 (s, 1H), 5.02 (q, J = 24.2 Hz, 2H), 4.44– 3.86 (m, 10H), 3.77 – 3.18 (m, 18H), 2.60 – 1.94 (m, 4H), 1.07 (m, 6H).

[0088] Polymer A-9-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirring was continued at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for another 12 h. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and the obtained viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) for precipitation. The precipitation was repeated three times, and the product was collected by filtration to obtain a light yellow powder of the phosphonic acid group-containing polymer 9a. 1 H NMR (500 MHz, Chloroform ) δ 7.53(s, 1H), 7.49 (s, 1H), 5.28 – 4.75 (m, 2H), 4.18 (ddd, J = 23.6, 16.8, 8.4 Hz,6H), 3.90 – 3.19 (m, 19H), 2.34 (td, J = 16.0, 1.4 Hz, 2H), 1.99 (m, 2H).

[0089] Example 10: Synthesis of a representative hole injection material 10a:

[0090]

[0091] A-1-4 (5.15 g, 10.0 mmol) and A-10-1 (diboronate) (6.22 g, 10.0 mmol) were weighed into a dry three-necked flask under nitrogen protection, and anhydrous toluene 150 mL was added to disperse / dissolve them; 15 mL (30.0 mmol, 3.0 eq) of a 2 M aqueous K2CO3 solution was added to form a toluene / aqueous two-phase system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were sequentially added as phase transfer catalysts. After the system was degassed by three times of vacuum / nitrogen alternation, the reaction was stirred at toluene reflux (about 110 °C) for 12 hours. After the reaction was completed, the reaction mixture was slowly poured into a large amount of methanol to precipitate the polymer solid. The obtained solid was collected by filtration, washed with a dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, and then washed with deionized water until neutral. The dried solid was subjected to Soxhlet extraction, and the solvents were used in the following order: methanol → acetone → n-hexane → chloroform. The chloroform extract was collected and concentrated under reduced pressure to obtain the target polymer A-10-2 as a light-colored solid. 1H NMR (500 MHz, Chloroform ) δ 7.61 (s, 1H), 7.32 (s, 1H), 5.01 (q, J = 24.3 Hz, 2H), 4.05 (m,10H), 2.77 – 1.97 (m, 4H), 1.85 – 0.64 (m, 33H).

[0092] Polymer A-10-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirring was continued at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for another 12 h. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and the resulting viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times. The precipitate was filtered to obtain a pale yellow powder of phosphonic acid-based polymer 10a. 1 H NMR (500 MHz, Chloroform ) δ 7.68(s, 1H), 7.62 (s, 1H), 4.98 (q, J = 24.2 Hz, 2H), 4.33 – 3.73 (m, 6H), 2.49 –2.20 (m, 2H), 2.20 – 1.85 (m, 2H), 1.91 – 0.63 (m, 27H).

[0093] Example 11: Synthesis of a representative hole injection material 11a:

[0094]

[0095] Under nitrogen protection, A-1-4 (5.15 g, 10.0 mmol) and A-11-1 (diboronate) (4.48 g, 10.0 mmol) were weighed into a dry three-neck flask, and anhydrous toluene 150 mL was added to disperse / dissolve; 2 M aqueous K2CO3 solution 15 mL (30.0 mmol, 3.0 eq) was added to form a toluene / water biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) as a phase transfer catalyst were added in turn. After three times of vacuum / nitrogen degassing, the system was stirred at toluene reflux for 12 hours. After the reaction was completed, it was cooled to room temperature, and the reaction solution was slowly poured into a large amount of methanol to precipitate the polymer solid. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, then washed with deionized water until neutral, and placed in a vacuum dryer at 40-50 °C. The dried solid was subjected to Soxhlet extraction, and the solvents were in the order of: methanol → acetone → n-hexane → chloroform. The chloroform extract layer was collected and concentrated under reduced pressure to obtain the target polymer A-11-2 as a light-colored solid. 1 H NMR (500 MHz, Chloroform ) δ 7.57 (s, 1H), 7.43 (s, 1H), 7.10 (s, 1H), 4.35 – 3.53 (m, 6H),2.93 – 1.91 (m, 6H), 1.75 – 0.49 (m, 21H).

[0096] The polymer A-11-2 (1.00 g) was dissolved in anhydrous dichloromethane (20 mL), and an excess of trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirred at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for 12 h. After the reaction was completed, it was concentrated under reduced pressure, and the obtained viscous liquid was slowly dropped into a large amount of anhydrous ether (200 mL) for precipitation, and the precipitation was repeated for 3 times, and the light yellow powder of phosphonic acid-based polymer 11a was obtained by filtration. 1 H NMR (500 MHz, Chloroform ) δ 7.60(s, 1H), 7.51 (s, 1H), 7.11 (s, 1H), 4.16 (t, J = 11.0 Hz, 2H), 3.05 – 1.84 (m,6H), 1.72 – 0.64 (m, 14H).

[0097] Example 12: Synthesis of a representative hole injection material 12a:

[0098]

[0099] A-1-4 (5.15 g, 10.0 mmol) and A-12-1 (diboronate) (6.92 g, 10.0 mmol) were weighed into a dry three-necked flask under nitrogen protection, and anhydrous toluene 150 mL was added to disperse / dissolve; K2CO3 2 M aqueous solution 15 mL (30.0 mmol, 3.0 eq) was added to form a toluene / water biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) as a phase transfer catalyst were added in turn. The system was degassed by vacuum-pumping and nitrogen-filling for three times, and then the reaction was stirred at toluene reflux (about 110 °C) for 12 hours. After the reaction was completed, the reaction solution was slowly poured into a large amount of methanol to precipitate the polymer solid. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligand / base, then washed with deionized water until neutral, and dried in vacuum at 40-50 °C. The dried solid was subjected to Soxhlet extraction, and the solvents were used in the following order: methanol → acetone → n-hexane → chloroform. The chloroform extract was collected and concentrated under reduced pressure to obtain the target polymer A-12-2 as a light-colored solid. 1 H NMR (500 MHz, Chloroform ) δ 7.86 (s, 1H), 7.33 (s, 1H), 4.49 – 3.64 (m, 14H), 3.46 –3.07 (m, 4H), 2.77 – 1.98 (m, 4H), 1.87 – 0.55 (m, 35H).

[0100] Polymer A-12-2 (1.00 g) was dissolved in anhydrous dichloromethane (CH2Cl2, 20 mL), and excess trimethylsilyl bromide (TMSBr, 2.00 g) was added. The mixture was stirred at room temperature for 12 h. Then anhydrous methanol 20 mL was added, and the stirring was continued at room temperature for 12 h. After the reaction was completed, the reaction solution was concentrated under reduced pressure, and the obtained viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) for precipitation. The precipitation was repeated for three times, and the product was collected by filtration as a light yellow powder. 1 H NMR (500 MHz, Chloroform ) δ 7.85(s, 1H), 7.32 (s, 1H), 4.60 – 3.14 (m, 14H), 2.62 – 2.21 (m, 2H), 2.19 – 1.86(m, 2H), 1.80 – 0.52 (m, 29H).

[0101] Example 13: Synthesis of a representative hole injection material 1b:

[0102]

[0103] Furancarbazole (A-13-1, 147.03 g, 1 mol) was dissolved in 1 L of anhydrous DMSO under nitrogen protection, and 10 equivalents of NaH (60% dispersion, 400 g, NaH 240 g, 10 mol) was added to form a sodium carbazole salt. Then diethyl (3-bromopropyl) phosphonate (A-13-2, 259.08 g, 1 mol) was dissolved in DMSO and added dropwise to the reaction solution, and the reaction was stirred at 60°C for 20 h. After the reaction was completed, it was poured into water, extracted with ethyl acetate, washed with saturated brine, and the organic phase was dried. The solvent was removed under reduced pressure, and the product was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 2:1) to obtain the alkylated product A-13-3. 1 H NMR (500 MHz, Chloroform ) δ 7.40 (d, J = 15.0 Hz, 2H), 6.80 (d, J = 15.0 Hz, 2H), 4.15 (t, J = 12.0 Hz, 2H), 4.00 (q, J = 12.0 Hz, 4H), 2.36 (t, J =11.1 Hz, 2H), 2.17 – 1.84 (m, 2H), 1.07 (t, J = 12.0 Hz, 6H).

[0104] The alkylated product A-13-3 (162.50 g, 0.50 mol) was dissolved in 1.0 L of chloroform under nitrogen protection and stirred to completely dissolve; another N-bromosuccinimide (NBS) (195.79 g, 1.10 mol, 2.2 eq) was prepared into a slurry of chloroform (about 500 mL). The reaction solution was cooled to 0-5 ℃, and the NBS slurry was added slowly in batches (control temperature rise). After the addition was completed, it was raised to the reflux temperature of chloroform, and stirred in the dark or weak light for 6 h under inert atmosphere. The reaction solution was cooled to room temperature, and the by-product succinimide solid was removed by filtration, the filter cake was washed with a small amount of chloroform and the washing liquid was combined. The combined organic phase was washed with 5% Na2S2O3 solution (to remove free bromine), saturated NaHCO3 solution (to neutralize the acid), and saturated brine in turn, dried over anhydrous MgSO4, filtered, and then the solvent was removed under reduced pressure. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate ≈ 8:1 → 4:1 gradient) to obtain the brominated product A-13-4. 1 H NMR (500 MHz, Chloroform ) δ 6.82 (s, 2H),4.16 (t, J = 15.2 Hz, 2H), 4.01 (q, J = 11.8 Hz, 4H), 2.36 (t, J = 10.6 Hz, 2H),2.20 – 1.68 (m, 2H), 1.07 (t, J = 11.8 Hz, 6H).

[0105] Under nitrogen, A-13-4 (4.80 g, 10.0 mmol) and A-13-5 (diboronate) (5.58 g, 10.0 mmol) were weighed into a dry three-necked flask and dissolved / dispersed in 150 mL of anhydrous toluene. A 2 M aqueous solution of K2CO3 (15 mL, 30.0 mmol, 3.0 eq) was added to form a toluene / aqueous biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. The system was degassed by three cycles of vacuum / nitrogen and the reaction was stirred at toluene reflux (~ 110 °C) for 12 h. After cooling to room temperature, the reaction was slowly poured into a large excess of methanol and the polymer precipitated. The resulting solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligand / base, and then with deionized water until neutral. The dried solid was subjected to Soxhlet extraction with solvents in the following order: methanol -> acetone -> n-hexane -> chloroform. The chloroform extract was collected and concentrated under reduced pressure to give the target polymer A-13-6 as a light-colored solid. 1 H NMR (500MHz, Chloroform ) δ 7.40 (d, J = 15.0 Hz, 2H), 6.80 (d, J = 15.0 Hz, 2H), 4.15(t, J = 12.0 Hz, 2H), 4.00 (q, J = 12.0 Hz, 4H), 2.36 (t, J = 11.1 Hz, 2H), 2.17 –1.84 (m, 2H), 1.07 (m, 6H).

[0106] Polymer A-13-6 (1.00 g) was dissolved in anhydrous dichloromethane (CH2Cl2, 20 mL) and excess trimethylsilyl bromide (TMSBr, 2.00 g) was added. The mixture was stirred at room temperature for 12 h. Anhydrous methanol (20 mL) was then added and stirring was continued at room temperature for another 12 h. After the reaction was completed, the mixture was concentrated under reduced pressure and the resulting viscous liquid was slowly added dropwise to a large excess of anhydrous diethyl ether (200 mL) to precipitate the polymer. The precipitation was repeated three times and the resulting light yellow powder was collected by filtration. 1H NMR (500 MHz, Chloroform ) δ 7.43(s, 1H), 7.35 (s, 1H), 7.29 (s, 1H), 6.78 (s, 1H), 4.14 (dt, J = 25.0, 10.2 Hz,6H), 2.53 – 1.61 (m, 8H), 1.58 – 0.71 (m, 23H).

[0107] Example 14: Synthesis of a representative hole injection material 12c:

[0108]

[0109] Selenophene carbazole (A-14-1, 27.4 g, 1 mol) was dissolved in 1 L of anhydrous DMSO under nitrogen protection, and 10 equivalents of NaH (60% dispersion, 400 g, NaH 240 g, 10 mol) was added to form a sodium carbazole salt. Then diethyl (3-bromopropyl) phosphonate (A-14-2, 259.08 g, 1 mol) was dissolved in DMSO and added dropwise to the reaction solution, and the reaction was stirred at 60°C for 20 h. After the reaction was completed, it was poured into water, extracted with ethyl acetate, washed with saturated brine, and the organic phase was dried. The solvent was removed under reduced pressure, and the alkylated product A-14-3 was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 2:1). 1 H NMR (500 MHz, Chloroform ) δ 7.23 (d, J = 14.8 Hz, 2H), 6.32 (d, J =15.0 Hz, 2H), 4.37 – 3.68 (m, 6H), 2.36 (td, J = 10.9, 0.8 Hz, 2H), 2.24 – 1.91(m, 2H), 1.07 (t, J = 22.0 Hz, 6H).

[0110] Under nitrogen protection, alkylated product A-14-3 (226.47 g, 0.50 mol) was dissolved in 1.0 L chloroform and stirred until completely dissolved; another N-bromosuccinimide (NBS) (195.79 g, 1.10 mol, 2.2 eq) was prepared into a slurry of chloroform (about 500 mL). The reaction solution was cooled to 0-5 ℃, and the NBS slurry was added slowly in batches (control temperature rise). After the addition was completed, it was raised to the reflux temperature of chloroform, and stirred in the dark or weak light for 6 h under inert atmosphere. The reaction solution was cooled to room temperature, and the by-product succinimide solid was removed by filtration, and the filter cake was washed with a small amount of chloroform and the wash was combined. The combined organic phase was washed with 5% Na2S2O3 solution (to remove free bromine), saturated NaHCO3 solution (to neutralize the acid), and saturated brine, dried over anhydrous MgSO4, filtered, and the solvent was removed under reduced pressure. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate) to obtain the brominated product A-14-4. 1 H NMR (500 MHz, Chloroform ) δ 6.77 (s, 2H), 4.41 – 3.77 (m,4H), 2.36 (td, J = 11.1, 0.8 Hz, 2H), 2.13 (m, 2H), 1.07 (t, J = 22.0 Hz, 6H).

[0111] Under nitrogen protection, A-14-4 (6.09 g, 10.0 mmol) and A-14-5 (diboronate) (6.92 g, 10.0 mmol) were weighed into a dry three-necked flask, and anhydrous toluene 150 mL was added to disperse / dissolve them; 2 M aqueous K2CO3 solution 15 mL (30.0 mmol, 3.0 eq) was added to form a toluene / water biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) were added as phase transfer catalysts. The system was degassed by three times of vacuum / nitrogen, and the reaction was stirred at toluene reflux (≈110 ℃) for 12 hours. After the reaction was completed, the reaction solution was cooled to room temperature, and the reaction solution was slowly poured into a large amount of methanol to stir and precipitate the polymer solid. The obtained solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligands / base, then washed with deionized water until neutral, and dried in vacuum at 40-50 ℃. The dried solid was subjected to Soxhlet extraction, and the solvents were used in sequence: methanol → acetone → n-hexane → chloroform. The chloroform extract was collected and concentrated under reduced pressure to obtain the target polymer A-14-6 as a light-colored solid. 1H NMR (500 MHz, Chloroform ) δ 7.07 (s, 1H), 7.05 (s, 1H), 4.42 - 3.67 (m, 15H), 3.52 - 3.16 (m, 4H), 2.55 - 1.92 (m, 4H), 1.76 - 0.65 (m, 38H).

[0112] Polymer A-14-6 (1.00 g) was dissolved in anhydrous dichloromethane (CH2Cl2, 20 mL), excess trimethylsilyl bromide (TMSBr, 2.00 g) was added, and stirring was continued at room temperature for 12 h. Subsequently, anhydrous methanol 20 mL was added, and stirring was continued at room temperature for 12 h. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and the obtained viscous liquid was slowly dropped into a large amount of anhydrous diethyl ether (200 mL) to precipitate, and the precipitation was repeated three times, and the precipitate was filtered to obtain a phosphonic acid group-containing polymer 12c as a light yellow powder. 1 H NMR (500 MHz, Chloroform ) δ 7.07 (s, 1H), 6.56 (s, 1H), 4.16 (dd, J = 16.1, 11.3 Hz, 6H), 3.79 (s, 4H), 3.51 - 3.14 (m, 4H), 2.54 - 1.82 (m, 4H), 1.82 - 1.05 (m, 23H), 1.04 - 0.55 (m, 6H).

[0113] Example 15: Synthesis of a representative hole injection material 12d:

[0114]

[0115] Methylpyrrolocarbazole (A-15-1, 173.10 g, 1 mol) was dissolved in 1 L of anhydrous DMSO under nitrogen protection, and 10 equivalents of NaH (60% dispersion, 400 g, NaH 240 g, 10 mol) was added to generate a sodium salt of carbazole. Subsequently, diethyl (3-bromopropyl) phosphonate (A-15-2, 259.08 g, 1 mol) was dissolved in DMSO, and was added dropwise to the reaction solution, and the reaction was stirred at 60°C for 20 h. After the reaction was completed, the reaction mixture was poured into water, extracted with ethyl acetate, washed with saturated brine, and the organic phase was dried, and the solvent was removed under reduced pressure, and the obtained product was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 2:1) to obtain an alkylated product A-15-3. 1 H NMR (500 MHz, Chloroform ) δ 6.66 (d, J= 15.0 Hz, 2H), 6.17(d, J = 15.0 Hz, 2H), 4.15 (t, J = 10.7 Hz, 2H), 4.00 (q, J = 11.8 Hz, 4H), 3.63(s, 6H), 2.36 (td, J = 11.3, 0.8 Hz, 2H), 2.23 – 1.94 (m, 2H), 1.07 (t, J = 11.8Hz, 6H).

[0116] The alkylated product A-15-3 (175.59 g, 0.50 mol) was dissolved in 1.0 L of chloroform under nitrogen protection, and stirred to completely dissolve; another N-bromosuccinimide (NBS) (195.79 g, 1.10 mol, 2.2 eq) was prepared into a slurry of chloroform (about 500 mL). The reaction solution was cooled to 0-5 ℃, and the NBS slurry was slowly added in batches (control temperature rise). After the addition was completed, it was raised to the reflux temperature of chloroform, and stirred under inert atmosphere for 6 h in the dark or weak light. The reaction solution was cooled to room temperature, and the by-product succinimide solid was removed by filtration, and the filter cake was washed with a small amount of chloroform and the washing liquid was combined. The combined organic phase was washed with 5% Na2S2O3 solution (to remove free bromine), saturated NaHCO3 solution (to neutralize the acid), and saturated brine, dried over anhydrous MgSO4, filtered, and the solvent was removed under reduced pressure. The residue was purified by silica gel column chromatography (petroleum ether / ethyl acetate) to obtain the brominated product A-15-4. 1 H NMR (500 MHz, Chloroform ) δ 6.86 (s, 2H), 4.16 (t, J = 15.1Hz, 2H), 4.01 (q, J = 11.8 Hz, 4H), 3.60 (s, 6H), 2.55 – 2.29 (m, 2H), 2.25 –1.83 (m, 2H), 1.07 (t, J = 11.8 Hz, 6H).

[0117] Under nitrogen, A-15-4 (5.06 g, 10.0 mmol) and A-14-5 (diboronate) (6.92 g, 10.0 mmol) were weighed into a dry three-necked flask and dissolved / dispersed in 150 mL of anhydrous toluene. 15 mL (30.0 mmol, 3.0 eq) of a 2 M aqueous solution of K2CO3 was added to form a toluene / aqueous biphasic system. Pd(PPh3)4 (0.231 g, 0.20 mmol, 2 mol%) and tetrabutylammonium bromide (TBAB, 96 mg, 0.30 mmol, 3 mol%) as phase transfer catalyst were added sequentially. The system was degassed by three cycles of vacuum / nitrogen and the reaction was stirred at toluene reflux (~ 110 °C) for 12 h. After cooling to room temperature, the reaction was slowly poured into a large excess of methanol and the polymer precipitated. The resulting solid was collected by filtration, washed with dilute hydrochloric acid solution (0.1 M) to remove inorganic salts and residual ligand / base, then with deionized water until neutral, and dried under vacuum at 40-50 °C. The dried solid was subjected to Soxhlet extraction with solvents in the following order: methanol -> acetone -> n-hexane -> chloroform. The chloroform extract was collected and concentrated under reduced pressure to give the target polymer A-15-6 as a light-colored solid. 1 H NMR (500 MHz, Chloroform ) δ 7.41 (s, 1H), 6.53 (s, 1H), 4.59 – 3.18 (m, 24H), 2.50 –2.23 (m, 2H), 2.20 – 1.91 (m, 2H), 1.72 – 0.59 (m, 35H).

[0118] The polymer A-15-6 (1.00 g) was dissolved in anhydrous dichloromethane (CH2Cl2, 20 mL) and excess trimethylsilyl bromide (TMSBr, 2.00 g) was added. The mixture was stirred at room temperature for 12 h. Subsequently, anhydrous methanol (20 mL) was added and the stirring was continued at room temperature for another 12 h. After the reaction was completed, the mixture was concentrated under reduced pressure and the resulting viscous liquid was slowly dropped into a large excess of anhydrous diethyl ether (200 mL) for precipitation. The precipitation was repeated three times and the resulting light yellow powder was collected by filtration. 1 H NMR (500 MHz, Chloroform ) δ 6.56(s, 1H), 6.53 (s, 1H), 4.17 (dd, J = 25.0, 14.2 Hz, 4H), 3.78 (dd, J = 121.2,86.2 Hz, 13H), 3.43 – 3.08 (m, 4H), 2.34 (dd, J= 17.4, 6.1 Hz, 2H), 2.19 –1.87 (m, 2H), 1.78 – 1.08 (m, 26H), 1.04 – 0.55 (m, 7H).

[0119] Example 16: Preparation and performance test of coaxial flexible OLED light-emitting wire

[0120] 1. Device preparation

[0121] (1) Coaxial core layer preparation: silver nanowires (AgNWs) dispersion liquid was spun into a conductive core wire with a diameter of about 30 pm by solution spinning technology. The obtained core wire was dried at 60 °C for 2 h to form a flexible and highly conductive core layer.

[0122] (2) Insulating isolation layer preparation: polyimide (PI) precursor solution was deposited on the core wire by inkjet printing to form an insulating isolation layer with a thickness of about 10 pm, and was cured at 120 °C for 30 min to ensure electrical insulation and mechanical flexibility.

[0123] (3) Anode layer preparation: On the outside of the insulating layer, ITO dispersion liquid was deposited by roll-to-roll inkjet printing to form an anode layer with a thickness of about 20 nm, which was further annealed under vacuum conditions after drying to improve the conductivity and light transmittance of the electrode.

[0124] (4) Hole injection layer (HIL) preparation: The phosphonic acid-based polymers synthesized in Examples la-12a, lb, 12c, 12d were respectively dissolved in a methanol / water mixed solvent (concentration 5 mg / mL) and deposited on the anode by inkjet printing, and a hole injection layer with a thickness of about 18 nm was obtained after drying at 80 °C for 10 min. The control device used PEDOT:PSS, 2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl] phosphonic acid (hereinafter referred to as “carbazole-PO3H2”) as the HIL.

[0125] (5) Hole transport layer (HTL) preparation: NPB solution (10 mg / mL, solvent chlorobenzene) was inkjet printed on the HIL and dried at 90 °C to obtain a hole transport layer with a thickness of about 40 nm.

[0126] (6) Light-emitting layer (EML) preparation: The host material (such as CBP) and the carbazole-containing boron-nitrogen compound guest were mixed at a weight ratio of 97:3, dissolved in chlorobenzene, and inkjet printed on the HTL to obtain a light-emitting layer with a thickness of about 30 nm after drying.

[0127] (7) Electron transport layer (ETL) preparation: Alq3 solution (10 mg / mL, chlorobenzene solvent) was inkjet printed on the EML, dried at 90 °C, to form an electron transport layer with a thickness of about 30 nm.

[0128] (8) Electron injection layer (EIL) preparation: LiF solution was deposited on the ETL to form an electron injection layer with a thickness of about 0.5 nm.

[0129] (9) Cathode layer preparation: Al cathode was deposited in a vacuum evaporation machine, with a thickness of about 80 nm, forming a coaxial symmetric structure with the anode.

[0130] (10) Flexible transparent encapsulation layer preparation: A polyurethane (PU) solution containing microcapsules was coated on the outer layer of the device, and after curing, a flexible transparent encapsulation layer with a thickness of about 30 μm was formed, which had both moisture-proof and certain self-repairing functions.

[0131] 2. Performance test method

[0132] Work function measurement: Kelvin probe was used to test the ΔWF (relative to bare ITO) of each HIL film layer.

[0133] Surface morphology: AFM was used to test the surface roughness (Ra) of the film.

[0134] Electroluminescence performance: Under direct current driving, the turn-on voltage, luminance-current-voltage (L-I-V) curve was tested, and the current efficiency was calculated.

[0135] Bending cycle test: The device was subjected to 10,000 cycles of bending with a radius of 5 mm, and the brightness retention rate was tested.

[0136] Hygrothermal aging test: The device was aged at 85 °C / 85% RH for 500 h, and the brightness retention rate was tested.

[0137] 3. Performance test results

[0138] Table 1 Comparison of device performance of different hole injection materials

[0139]

[0140] 4. Results analysis

[0141] (1) Heteroatom effect

[0142] Under the same substituent condition, the difference of X significantly affects the device performance: for example, O (1b) shows higher work function improvement and lower turn-on voltage, while Se (12c) is relatively weak, and N-CH3 (12d) is at an intermediate level.

[0143] (2) Substituent difference

[0144] In all examples, Ar is an electron-donating substituent. Different substituents have certain effects on the energy level matching, film forming property, and device stability of the material, resulting in differences in ΔWF, surface roughness, and device efficiency of each material.

[0145] The overall trend shows that the modification of the molecular structure can regulate the device performance within a certain range, verifying the applicability and universality of the designed material.

[0146] (3) Small molecule comparison

[0147] Compared with PEDOT:PSS, the phosphorus-containing small molecule modifier represented by carbazole-PO3H2 does have certain improvement in work function adjustment and device efficiency, but its limitations are also very obvious: it performs poorly in bending cycle and humidity and heat environment retention, and can only bring moderate performance improvement. In contrast, the polymer hole injection material of the present application is significantly superior to the small molecule control in all the above key performance indicators. The results show that the multiple synergistic effects between the polymer main chain and the phosphate group can simultaneously optimize the energy level matching, improve the film uniformity, and enhance the mechanical flexibility, and the overall effect is much better than that of the single-function small molecule modifier.

[0148] It should be noted that there are indeed many carbazole phosphate derivatives in actual research and application, including small molecules and polymers. The choice of carbazole-PO3H2 as a comparative example is because it is the most common, clear structure and easy to compare representative small molecule, which can effectively reflect the difference between "single small molecule modification" and "polymer synergistic effect". At the same time, the systematic advantages of the material of the present application in many performance indicators do not depend on the specific type of the comparative example, so whether the control object is a carbazole phosphate small molecule or an existing carbazole phosphate polymer, the polymer material of the present application can maintain better overall performance.

[0149] (4) Overall conclusion

[0150] Compared with PEDOT:PSS and carbazole-PO3H2 control, the phosphate group polymer HIL material of the present application significantly improves the device performance: the turn-on voltage is reduced by about 0.6-0.8 V, the current efficiency is increased by 35-45%, the maximum brightness is increased by 40-50%, and the bending and humidity and heat stability is increased by 20-30 percentage points.

[0151] The hole injection material of the present application can have high work function adjustment ability, excellent interface adhesion, mechanical flexibility and environmental stability, and can be adapted to a hole injection material for a roll-to-roll continuous production process, to promote the industrial application of high-performance coaxial flexible OLED light emitting lines.

[0152] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A flexible electroluminescent wire, characterized in that The OLED layer includes an anode, a hole transport layer, and a hole injection layer between the anode and the hole transport layer, and the material structure of the hole injection layer is as follows: X is S, O, Se or N-R, R is an alkyl or aryl substituent; n is a natural number, n = 1-100; y is an integer greater than or equal to 0; Ar is selected from the following: R' is selected from H, alkyl, alkoxy, oligoether.

2. The flexible electroluminescent wire of claim 1, wherein, The OLED layer includes an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode arranged in sequence.

3. The flexible electroluminescent line according to claim 1, characterized in that, A transparent encapsulation layer is further provided outside the OLED layer.

4. The flexible electroluminescent wire of claim 1, wherein, The material of the hole injection layer is selected from the following: 。

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