CN106699746A - Bipolar small molecular light-emitting material based on naphthothiodibenzofuran unit as well as preparation method and application of bipolar small molecular light-emitting material - Google Patents

Abstract

The invention discloses a bipolar small molecule luminescent material based on a naphthothiooxyfluorene unit, a preparation method and an application thereof. In the present invention, the naphthothiooxyfluorene unit is used as the nucleus, and the donor unit is connected to the naphthothiooxyfluorene unit through Suzuki coupling reaction, so as to obtain the bipolar small molecule luminescent material based on the naphthothiooxyfluorene unit . The naphthothiooxyfluorene-based bipolar small molecule luminescent material of the present invention has good solubility, and after being dissolved in an organic solvent, the luminescent layer of a light-emitting diode is prepared by spin coating, inkjet printing or printing to form a film. The bipolar small molecule luminescent material based on naphthothiooxyfluorene of the present invention contains both an electron transport unit and a hole transport unit, which is beneficial to the improvement of the device efficiency of the material.

Description

A bipolar small molecule luminescent material based on naphthothiooxyfluorene unit and its preparation Method and Application

technical field

The invention belongs to the field of organic photoelectric technology, in particular to a bipolar small molecule luminescent material and a preparation method and application thereof.

Background technique

Organic light-emitting diodes (OLEDs) have attracted widespread attention due to their high efficiency, low-voltage drive, and ease of large-area fabrication. The research on OLED began in the 1950s. Until 1987, Dr. Deng Qingyun of Kodak Company of the United States developed an OLED device with a sandwich device structure. The luminous brightness of the OLED device can reach 1000cd m ^-2 when driven by a 10V DC voltage, making OLED an epoch-making achievement. develop.

The OLED device consists of a cathode, an anode, and an organic layer in the middle. The organic layer generally includes an electron transport layer, a light-emitting layer, and a hole transport layer. First, electrons and holes are injected from the cathode and anode respectively, and migrate in the functional layer respectively, and then Electrons and holes form excitons at suitable positions, the excitons migrate within a certain range, and finally the excitons emit light.

In order to realize the commercialization of organic/polymer electroluminescent devices as soon as possible, in addition to meeting the requirements of full-color display, high monochromatic purity, good thermochemical stability and long service life, it is also desirable that the device has high luminous efficiency . One of the main factors affecting the efficiency of OLED devices is the imbalance of electron and hole transport and injection in the material itself. Therefore, in order to obtain high-efficiency OLED devices, the balance between electron-hole transport and injection of materials must be adjusted reasonably.

In recent years, ambipolar materials have attracted extensive attention in the field of organic electroluminescence due to their balanced hole and electron carrier flow, and the materials can simplify the structure of devices. This new type of technology is not only favored by scientists in the field of theoretical research, but also is gradually moving towards industrial production, so the development of bipolar materials has practical value.

Contents of the invention

The object of the present invention is to provide a bipolar small molecule luminescent material based on naphthothiooxyfluorene unit. The material has good electron and hole transport capabilities, which can balance the transport of carriers, allowing more excitons to recombine effectively, thereby improving luminous efficiency.

The object of the present invention is also to provide a method for preparing the bipolar small molecule luminescent material based on naphthothioxyfluorene units.

The purpose of the present invention is also to provide the application of the bipolar small molecule luminescent material based on naphthothiooxyfluorene unit in the preparation of the luminescent layer of the light emitting diode.

The specific technical scheme of the present invention is as follows.

A bipolar small molecule luminescent material based on a naphthothiooxyfluorene unit has the following structural formula:

In the formula, R is an aryl group, triphenylamine, a straight chain or branched chain alkyl group with 1-20 carbon atoms, an alkoxy group with 1-20 carbon atoms, or -(CH ₂ ) _n -O-(CH ₂ ) _m -X, wherein, n=1-10, m=1-10, X is any one of the following structures:

Ar ₁ is a donor unit, which is any one of the following structures:

The preparation method of the bipolar small molecule luminescent material based on the naphthothiooxyfluorene unit comprises the following steps:

The naphthothiofluorene unit is used as the nucleus, and the donor unit is connected to the naphthothiofluorene unit through a Suzuki coupling reaction to obtain the bipolar small molecule luminescent material based on the naphthothiofluorene unit.

Further, the temperature of the Suzuki coupling reaction is 110-160° C., and the time is 18-24 hours.

Further, the Suzuki coupling reaction is carried out under an argon atmosphere.

The application of the bipolar small molecule luminescent material based on the naphthothioxyfluorene unit in the preparation of the light emitting layer of the light emitting diode, using the bipolar small molecule luminescent material based on the naphthothioxyfluorene unit The organic solvent is dissolved, and the light-emitting layer of the light-emitting diode is obtained by spin-coating, ink-jet printing or printing to form a film; the light-emitting diode based on the light-emitting layer can be applied and prepared into a flat panel display.

Further, the organic solvent includes chlorobenzene.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention centers on the naphthylthiofluorene unit for the first time, which is a very good electron transport unit, which is beneficial to the injection and transmission of electrons, and then introduces the electron donor unit to form a D-A-D type bipolar small Molecular luminescent materials;

(2) The bipolar small-molecule luminescent material based on naphthothioxyfluorene of the present invention has a higher fluorescence quantum yield because it contains both an electron transport unit and a hole transport unit, which is conducive to improving the device efficiency of the material ;

(3) The bipolar small-molecule luminescent material based on naphthothioxyfluorene of the present invention has good solubility, and is processed into a film by spin coating, inkjet printing or printing;

(4) The bipolar small-molecule luminescent material based on naphthothiooxyfluorene of the present invention has good solubility, film-forming properties and film shape stability, and the luminescent layer based on this material does not need to be used in the preparation of electroluminescent devices. Annealing treatment makes the preparation process simpler.

Description of drawings

Fig. 1 is the thermal analysis spectrogram of compound D1;

Fig. 2 is the photoluminescence spectrogram of compound D2 in thin film state;

Fig. 3 is the photoluminescence spectrogram of compound D3 in thin film state;

Fig. 4 is the current density-lumen efficiency spectrum of compound D4.

detailed description

The present invention will be described in further detail below in conjunction with the examples, but the embodiments of the present invention are not limited to the following examples.

Example 1

Preparation of methyl 1-bromo-naphthoate

Under an argon atmosphere, 1-bromo-2-naphthoic acid (10g, 39.83mmol) was added to a two-neck flask, then 100mL of methanol was added, and then concentrated sulfuric acid (39.06mg, 398.29umol) was added dropwise, heated to 110°C, Reacted for 18h; poured the reaction mixture into water, extracted with ethyl acetate, washed the organic layer with brine, and dried with anhydrous magnesium sulfate; after the solution was concentrated, a white solid crude product was obtained, which was purified by silica gel column chromatography (elution The solvent is petroleum ether/dichloromethane=3/1, v/v), and the product is placed in a refrigerator to obtain a white solid with a yield of 85%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 2

Preparation of 2,8-Dibromothiofluorene

Under an argon atmosphere, add thiofluorene (20g, 108.54mmol) into a 250ml two-necked bottle, then add 100ml of chloroform to dissolve completely, add 0.5g of iodine, and add liquid bromine (38.16 g, 238.80 mmol), the reaction solution was stirred in an ice bath at 0°C for 2 hours, then stirred at room temperature for 2 hours, adding saturated sodium bisulfite to quench liquid bromine, pouring the reaction mixture into water, and extracting with ethyl acetate , the organic layer was washed completely with brine, and dried by adding anhydrous magnesium sulfate; after the solution was concentrated, a white solid crude product was obtained, which was then recrystallized with chloroform, with a yield of 85%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 3

Preparation of 2,8-diboronate thiofluorene

Under an argon atmosphere, 2,8-dibromothiofluorene (10 g, 29.24 mmol) was dissolved in 180 mL of refined tetrahydrofuran (THF), and 1.6 mol.L ^-1 of n-butyl was gradually added dropwise at -78°C Lithium 28mL, react for 2 hours, then quickly add 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborane 25mL, continue reaction at -78°C for 1 hour, slowly warming up to room temperature, and reacting for 24 hours; the reaction mixture was poured into water, extracted with ethyl acetate, the organic layer was washed completely with brine, and dried with anhydrous magnesium sulfate; after the solution was concentrated, a light yellow viscous The crude product was purified by silica gel column chromatography (petroleum ether/ethyl acetate=20/1 as eluent, v/v), and the product was placed in a refrigerator to obtain a white solid with a yield of 70%. ¹ H NMR and GC-MASS tests show that it is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 4

Preparation of compound M1

Under argon atmosphere, 2,8-diborate thiofluorene (5g, 11.46mmol) and 1-bromo-2-naphthoic acid methyl ester (7.6g, 28.66mmol) were added to the two-necked flask, and then 100ml Completely dissolve toluene, then add sodium carbonate (6.07g, 57.32mmol), tetrabutylammonium bromide (312.01mg, 967.86umol) and tetrakistriphenylphosphopalladium (264.93mg, 229.26umol), and react at 110°C 18h; the reaction mixture was poured into water, extracted with ethyl acetate, the organic layer was washed completely with brine, and then dried with anhydrous magnesium sulfate; after the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether/distillate was selected as the eluent). Chloromethane=7/1, v/v), a white solid was finally obtained with a yield of 80%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 5

Preparation of Compound M2

Under an argon atmosphere, add compound M1 (10g, 18.10mmol) into a single-necked bottle, and then add 50ml of anhydrous THF to dissolve completely; then react the reaction solution at 0°C for 1h, and then add n-octyl bromide dropwise Magnesium (C ₈ H ₁₇ MgBr), the mixture was reacted at room temperature for 18 hours; water was added to the reaction solution to quench the reaction, extracted with ethyl acetate, the organic layer was washed completely with brine, and dried with anhydrous magnesium sulfate After the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether/dichloromethane=3/1, v/v was selected as the eluent), and the product was placed in a refrigerator to obtain a white solid with a yield of 80%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 6

Preparation of compound M3

Under an argon atmosphere, compound M2 (5 g, 5.29 mmol) was dissolved in 50 ml of dichloromethane, and boron trifluoride ether solution (439.59 mg, 6.48 mmol) was added dropwise at room temperature for 18 h; After extraction, the organic layer was completely washed with salt water, and then dried with anhydrous magnesium sulfate; after the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether was selected as the eluent), and the product was placed in a refrigerator to obtain a white solid with a yield of 90%. . ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 7

Preparation of compound M4

Under argon atmosphere, compound M3 (5g, 5.50mmol) was dissolved in 50mL of dichloromethane, then iron powder (185.35mg, 3.32mmol) was added, and liquid bromine (1.93g, 12.10mmol) was added dropwise. React at room temperature for 18 hours; extract with ethyl acetate, wash the organic layer completely with brine, and add anhydrous magnesium sulfate to dry; after the solution is concentrated, purify with silica gel column chromatography (petroleum ether is selected as the eluent), and the yield is 70% . ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 8

Preparation of compound M5

Under an argon atmosphere, add compound M4 into a 250ml two-necked flask, add acetic acid to dissolve it, then add hydrogen peroxide (H ₂ O ₂ ), heat to 80°C, and react for 16 hours; extract with ethyl acetate, and use After fully washed with saline, it was dried by adding anhydrous magnesium sulfate; after the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether was selected as the eluent), and the yield was 75%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 9

Preparation of triphenylamine borate

Under an argon atmosphere, 4-bromotriphenylamine (5 g, 15.52 mmol) was dissolved in 180 mL of refined THF, and 28 mL of 1.6 mol L ^-1 n-butyllithium was gradually added dropwise at -78 °C, and reacted for 2 hours. Then 25 mL of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborane was added quickly, the reaction was continued at -78°C for 1 hour, and the temperature was slowly raised to room temperature. React for 24 hours; pour the reaction mixture into water, extract with ethyl acetate, wash the organic layer with brine, and add anhydrous magnesium sulfate to dry; Purification (petroleum ether/ethyl acetate=20/1 as eluant, v/v), the product was placed in a refrigerator to obtain a white solid with a yield of 70%. ¹ H NMR and GC-MASS tests show that it is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 10

Preparation of compound M6

Under an argon atmosphere, 3,6-dibromocarbazole (5g, 915.38mmol) and triphenylamine borate (17.14g, 46.15mmol) were added to the two-necked flask, and then 100ml of toluene was added to dissolve completely, and then Sodium carbonate (8.15g, 76.92mmol), tetrabutylammonium bromide (312.01mg, 967.86umol) and tetrakistriphenylphosphopalladium (355.56mg, 307.69umol), reacted at 110°C for 18h; pour the reaction mixture into In water, extracted with ethyl acetate, the organic layer was washed completely with brine, and then dried with anhydrous magnesium sulfate; after the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether/dichloromethane=6/1 was selected as the eluent, v/v), a white solid was finally obtained with a yield of 80%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 11

Preparation of compound M7

Under an argon atmosphere, 3,6-dibromocarbazole (5g, 15.38mmol) and 3,6-di-tert-butylcarbazole (12.90g, 46.15mmol) were added to a 100ml two-necked bottle, and toluene was added for complete Dissolve, then add palladium acetate (69.08mg, 307.69umol) and tri-tert-butylphosphine (124.50mg, 615.39umol), and react at 110°C for 18h; pour the reaction mixture into water, extract with ethyl acetate, and wash the organic layer with After being completely washed with brine, it was dried by adding anhydrous magnesium sulfate; after the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether/dichloromethane=4/1, v/v was selected as the eluent), and finally a white solid was obtained. Rate 80%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Example 12

Preparation of Compound D1

Under an argon atmosphere, compound M5 (1g, 909.73umol) and triphenylamine borate (1.01g, 2.73mmol) were added to a two-necked flask, and then 100ml of toluene was added to dissolve completely, and then sodium carbonate (482.10mg, 4.55mmol), tetrabutylammonium bromide (312.01mg, 967.86umol) and tetrakistriphenylphosphine palladium (21.02mg, 18.19umol), reacted at 110°C for 18h; poured the reaction mixture into water and washed with ethyl acetate After extraction, the organic layer was completely washed with brine, and then dried with anhydrous magnesium sulfate; after the solution was concentrated, it was purified by silica gel column chromatography (eluent selected petroleum ether/dichloromethane=5/1, v/v), and finally A white solid was obtained in 80% yield. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the preparation chemical reaction equation is as follows:

The thermal analysis spectrum of the obtained compound D1 is shown in FIG. 1 . It can be seen from the figure that the thermal decomposition temperature of the compound is 415° C., indicating that the compound D1 has good thermal stability.

Example 13

Preparation of Compound D2

Under an argon atmosphere, compound M5 (1g, 909.73mol) and 3,6-di-tert-butylcarbazole (762.59mg, 2.73mmol) were added to a two-necked flask, and then 100ml of toluene was added to completely dissolve it, and then acetic acid was added Palladium (4.08mg, 18.19umol) and tri-tert-butylphosphine (7.36mg, 36.39umol) were reacted at 110°C for 18h; the reaction mixture was poured into water, extracted with ethyl acetate, and the organic layer was washed completely with brine , added anhydrous magnesium sulfate to dry; after the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether/dichloromethane=6/1, v/v was selected as the eluent), and finally a white solid was obtained with a yield of 85%. ¹ HNMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

The photoluminescence spectrum of compound D2 in the thin film state is shown in Figure 2. It can be seen from the figure that the maximum emission peak of compound D2 is located at 510nm.

Example 14

Preparation of Compound D3

Under an argon atmosphere, M5 (1g, 909.73umol) and M6 (1.78g, 2.73mmol) were added to a two-necked flask, and then 100ml of toluene was added for complete dissolution, then palladium acetate (4.08mg, 18.19umol) and tris Tert-butylphosphine (7.36mg, 36.39umol), reacted at 110°C for 18h; poured the reaction mixture into water, extracted with ethyl acetate, washed the organic layer with brine, and dried with anhydrous magnesium sulfate; the solution was concentrated Afterwards, it was purified by silica gel column chromatography (petroleum ether/dichloromethane=6/1, v/v was selected as the eluent), and finally a white solid was obtained with a yield of 80%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

The photoluminescence spectrum of compound D3 in the thin film state is shown in Figure 3. It can be seen from the figure that the maximum emission peak of compound D3 is located at 500nm.

Example 15

Preparation of Compound D4

Under an argon atmosphere, compound M5 (1g, 909.73umol) and compound M7 (1.58g, 2.73mmol) were added to a two-neck flask, then 100ml of toluene was added to completely dissolve, and then palladium acetate (4.08mg, 18.19umol) was added React with tri-tert-butylphosphine (7.36mg, 36.39umol) at 110°C for 18h; pour the reaction mixture into water, extract with ethyl acetate, wash the organic layer completely with brine, and dry with anhydrous magnesium sulfate; After the solution was concentrated, it was purified by silica gel column chromatography (petroleum ether/dichloromethane=6/1, v/v was selected as the eluent), and finally a white solid was obtained with a yield of 80%. ¹ H NMR, ¹³ CNMR, MS and elemental analysis results show that the obtained compound is the target product, and the chemical reaction equation of the preparation process is as follows:

Compound D4 is based on the device structure: the current density-lumen efficiency spectrum of ITO/PEDOT/EML/CsF/Al is shown in Figure 4. It can be seen from the figure that the maximum lumen efficiency of the device is 3.2cd/A.

Example 16

Fabrication of Electroluminescent Devices Based on Small Molecule Materials

On the pre-made indium tin oxide (ITO) glass with a sheet resistance of 20Ω/□, it was cleaned with acetone, detergent, deionized water and isopropanol in sequence, and plasma was treated for 10 minutes; Polyethoxythiophene (PEDOT:PSS) film doped with polystyrenesulfonic acid, with a thickness of 150nm; the PEDOT:PSS film was dried in a vacuum oven at 80°C for 8 hours; then bipolar small molecule luminescent materials D1, The chlorobenzene solution (1wt%) of D2, D3, D4 is spin-coated on the surface of PEDOT:PSS film, and thickness is 80nm; Finally, a thin layer of CsF (1.5nm) and 120nm thick metal Al layer are successively vapor-deposited on the light-emitting layer .

Table 1 shows the photoelectric performance test results of the electroluminescent devices based on compounds D1-D4.

Table 1 Photoelectric properties of electroluminescent devices based on compounds D1～D4

It can be seen from Table 1 that compounds D1, D2, D3, and D4 are based on the device structure: the maximum lumen efficiency of ITO/PEDOT/EML/CsF/Al is 1.15cd/A, 1.56cd/A, 1.612cd/A, 2.94cd/A .

The photoluminescence spectrum of compound D2 in the thin film state is shown in Figure 2. It can be seen from the figure that the maximum emission peak of compound D2 is located at 510nm.

The photoluminescence spectrum of compound D3 in the thin film state is shown in Figure 3. It can be seen from the figure that the maximum emission peak of compound D3 is located at 500nm.

Compound D4 is based on the device structure: the current density-lumen efficiency spectrum of ITO/PEDOT/EML/CsF/Al is shown in Figure 4. It can be seen from the figure that the maximum lumen efficiency of the device is 3.2cd/A.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention All should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (6)

1. A bipolar small molecule luminescent material based on naphthothiooxyfluorene unit, characterized in that it has the following structural formula: In the formula, R is an aryl group, triphenylamine, a straight chain or branched chain alkyl group with 1-20 carbon atoms, an alkoxy group with 1-20 carbon atoms, or -(CH ₂ ) _n -O-(CH ₂ ) _m -X, wherein, n=1-10, m=1-10, X is any one of the following structures: Ar ₁ is a donor unit, which is any one of the following structures: 2. the preparation method of a kind of bipolar small molecule luminescent material based on naphthothiooxyfluorene unit according to claim 1, is characterized in that, comprises the steps: The naphthothiofluorene unit is used as the nucleus, and the donor unit is connected to the naphthothiofluorene unit through a Suzuki coupling reaction to obtain the bipolar small molecule luminescent material based on the naphthothiofluorene unit. 3. The preparation method of a bipolar small molecule luminescent material based on naphthothioxyfluorene unit according to claim 2, characterized in that, the temperature of the Suzuki coupling reaction is 110-160°C, and the time is 18-20 hours. 4 . The preparation method of a bipolar small molecule luminescent material based on naphthothioxyfluorene units according to claim 2 , wherein the Suzuki coupling reaction is carried out under an argon atmosphere. 5. The application of a kind of bipolar small molecule luminescent material based on naphthothiooxyfluorene unit in the preparation of light-emitting layer of light-emitting diode according to claim 1, characterized in that, the naphthothiooxyfluorene unit based The bipolar small molecule luminescent material is dissolved in an organic solvent and formed into a film by spin coating, inkjet printing or printing to obtain the luminescent layer of the light emitting diode. 6. application according to claim 5, is characterized in that, described organic solvent comprises chlorobenzene.