Chiral liquid crystal host material, preparation method and application thereof

Abstract

The application belongs to the technical field of organic electroluminescent materials, and specifically discloses a chiral liquid crystal host material and a preparation method and application thereof. A chiral octahydrobinaphthalene or chiral binaphthalene is used as a chiral construction source, 9,9'-(1,3-phenyl)di-9H-carbazole (mCP) or 9-(3-(9H-carbazole-9-yl)phenyl)-9H-carbazole-3-carbonitrile (mCPCN) or other light-emitting host units and liquid crystal units are connected in a non-conjugated manner to construct a chiral liquid crystal host material. The chiral liquid crystal host material is prepared into a circularly polarized organic light-emitting diode with high light-emitting asymmetry factor and high light-emitting efficiency through a solution processing drop coating film method, and has very important significance for the application and popularization of CP-OLEDs.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic electroluminescent materials, and particularly discloses a chiral liquid crystal host material and a preparation method and application thereof. BACKGROUND

[0002] In an organic light-emitting diode (OLED) device structure, in order to improve the light-emitting performance of the device, the light-emitting layer mostly adopts a host-guest structure, that is, a small amount of guest light-emitting material is doped into a host light-emitting material, and therefore the performance of the host material is particularly important. Since Meijer et al. first tried to obtain direct circularly polarized light (CP) from an OLED in 1997, people have carried out a large amount of research on the development of circularly polarized organic light-emitting diodes (CP-OLEDs). Circularly polarized electroluminescence (CPEL) based on OLEDs has attracted more and more attention due to its efficient ability to directly produce CP light and wide application in the fields of 3D display, spin rotation information communication, optical information storage and the like.

[0003] However, the current research on CP-OLEDs mainly focuses on the light-emitting guest material, and the research on chiral host materials is less. The key problems in the research on chiral host materials are (1) chiral energy transfer can be transferred to achiral guest materials, but the transfer mechanism needs to be further studied, and (2) the light-emitting asymmetry factor (g lum ) of most materials is relatively small, mostly 10 -3 to 10 -2 , and the CPEL signal of the prepared CP-OLED device is also very weak, which is difficult to have commercial application value. Therefore, it is of great significance to study and prepare circularly polarized organic light-emitting diodes (CP-OLEDs) with high light-emitting asymmetry factor and high light-emitting efficiency. SUMMARY

[0004] The application constructs a chiral liquid crystal host material of (R / S)-2LC and (R / S)-4LC and the like by taking chiral octahydrobinaphthyl or chiral binaphthyl as a chiral building block, connecting 9,9'-(1,3-phenyl)di-9H-carbazole (mCP) or 9-(3-(9H-carbazole-9-yl)phenyl)-9H-carbazole-3-carbonitrile (mCPCN) or other light-emitting host units and liquid crystal units in a non-conjugated manner, which can be used as a light-emitting host material in circularly polarized organic light-emitting diodes (CP-OLEDs). The chiral energy transfer mechanism from the chiral host to the achiral guest is also studied, which is of great significance for exploring high-efficiency circularly polarized light-emitting materials.

[0005] In order to achieve the above technical purposes, the application provides a chiral liquid crystal host material containing a chiral octahydrobinaphthyl or chiral binaphthyl unit, which has the following structure:

[0006]

[0007] Another object of the present application is to provide the application of the chiral liquid crystal host material, using (R / S)-4LC as the chiral host material, inorganic non-chiral light-emitting material quantum dots or organic non-chiral light-emitting material as the guest material, and using the solution processing drop coating film method to prepare the high-efficiency CP-OLED from the organic chiral host material to the inorganic non-chiral guest material quantum dots for the first time.

[0008] Compared with the prior art, the technical scheme of the present application has the beneficial effects that:

[0009] (1) The chiral liquid crystal host material prepared by the present application has circularly polarized light-emitting performance related to the ordered arrangement of the molecules under specific conditions, and has a very obvious CPL signal in the drop-coated and naturally volatilized thin film, and the strength of the CPL signal is related to the concentration of the prepared solution, and the CPL signal increases with the increase of the concentration of the prepared solution, and reaches the maximum in the 40mg / mL toluene solution, and the g lum are-0.71 and 0.73, respectively.

[0010] (2) The chiral energy transfer of the material of the present application has universality, which can not only be transferred to inorganic non-chiral quantum dot light-emitting materials, but also to organic non-chiral light-emitting materials (phosphorescence, TADF, etc.), and the strength of the chiral signal depends on the ordered arrangement of the molecules of (R / S)-4LC under specific conditions, and the chiral host material has great commercial application value.

[0011] (3) The material of the present application as the chiral host material, inorganic non-chiral light-emitting material quantum dots as the guest material, uses the solution processing drop coating film method to prepare the high-efficiency CP-OLED from the organic chiral host material to the inorganic non-chiral guest material quantum dots for the first time. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The ultraviolet-visible light absorption spectrum and photoluminescence spectrum of the compound (R)-2LC, (R)-4LC and the host material mCPCN prepared in Example 1 in toluene solution.

[0013] Figure 2 The low-temperature fluorescence and low-temperature phosphorescence spectrum of the compound (R)-2LC, (R)-4LC and the host material mCPCN prepared in Example 1 in toluene solution at 77K.

[0014] Figure 3 The TGA curve of the compound (R)-2LC and (R)-4LC prepared in Example 1 of the present application.

[0015] Figure 4Transient fluorescence spectra of pure thin films of compound (R)-2LC and (R)-4LC prepared in Example 1 of the present application.

[0016] Figure 5 DSC plots of compound (R)-2LC and (R)-4LC prepared in Example 1 of the present application (a) and POM plot of (R)-4LC during cooling process (b).

[0017] Figure 6 CPL spectra of compound (R / S)-4LC prepared in Example 1 of the present application in spin-coated thin film, toluene solution and drop-cast thin film (a) and g lum and CPL spectra of (R / S)-4LC in drop-cast thin film at different concentrations.

[0018] Figure 7 CD and CPL spectra of compound (R / S)-4LC prepared in Example 1 of the present application in drop-cast thin film at different concentrations.

[0019] Figure 8 UV-Vis absorption and photoluminescence spectra of compound (R)-4LC prepared in Example 1 of the present application in toluene solution (10 -5 M) (a); photoluminescence spectra (b), CD spectra (c) and CPL spectra (d) of (R)-4LC and quantum dots drop-cast thin film at different doping ratios (wt%).

[0020] Figure 9 Performance of CP-OLED device prepared by compound (R)-4LC prepared in Example 1 of the present application as chiral host material and inorganic achiral guest material quantum dots (QD).

[0021] Figure 10 Application of compound (R / S)-4LC prepared in Example 1 of the present application in other organic achiral luminescent guest materials.

[0022] Figure 11 Performance of CP-OLED device prepared by compound (R)-4LC prepared in Example 1 of the present application as chiral host material and organic achiral guest material Ir(mppy)3.

[0023] Figure 12 Performance of CP-OLED device prepared by compound (R)-4LC prepared in Example 1 of the present application as chiral host material and organic achiral guest material DMAC-TRZ. DETAILED DESCRIPTION

[0024] The following specific examples are intended to further illustrate the present application, but these specific embodiments are not in any way limiting to the scope of the present application.

[0025] Example 1

[0026] The synthesis route of chiral liquid crystal host material is as follows:

[0027]

[0028] Synthesis of compound 1 : In a 250 mL single neck flask, 2,3-difluoro-4- ethoxybenzoic acid (10.0 g, 50.0 mmol), 1 -iodo-4-(4-pentylcyclohexyl)benzene (18.0 g, 50.0 mmol), tetrakis(triphenylphosphine)palladium (0.5 g, 0.5 mmol), 2.0 mol / L aqueous potassium carbonate (30 mL) and 40 mL ethanol and 180 mL toluene were added successively. The reaction system was replaced with nitrogen (3 times) and then refluxed at 80 °C for 24 h. After cooling, the solvent was removed by rotary evaporator, and then extracted with dichloromethane (CH2Cl2) (3 x 60 mL) after adding water, washed with water (3 x 80 mL), dried over anhydrous magnesium sulfate, filtered and collected the filtrate, and then the solvent was removed to obtain white crude product 17.7 g with a yield of 92%. The crude product can be directly used in the next step.

[0029] Synthesis of compound 2: In a 500 mL three-neck flask, compound 1 (18 g, 48 mmol) was added and dissolved with dry CH2Cl2(200 mL). The reaction system was replaced with nitrogen (3 times), and then boron tribromide (15.0 g, 60.0 mmol) was slowly added dropwise at -78 °C. After stirring for one hour at this condition, the temperature was raised to room temperature and the reaction was carried out overnight. After cooling, ice water was added dropwise to quench the remaining boron tribromide, and then the organic phase was washed with aqueous sodium carbonate solution (3 times) and dried over anhydrous magnesium sulfate. After filtering and collecting the filtrate, the solvent was removed by rotary evaporator. Finally, white crude product 15.3 g was obtained with a yield of 89%. The crude product can be directly used in the next step.

[0030] Synthesis of compound 3: In a 500 mL single neck flask, compound 2 (10.0 g, 26.0 mmol), 1,6-dibromo hexane (31.0 g, 130.0 mmol), potassium carbonate (18.0 g, 130.0 mmol) and 150 mL acetone were added successively. The reaction system was replaced with nitrogen (3 times) and then refluxed at 80 °C for 24 h. After cooling, the solvent was removed by rotary evaporator, and then extracted with DCM (3 x 60 mL) after adding water, washed with water (3 x 80 mL), dried over anhydrous magnesium sulfate, filtered and collected the filtrate, and then the solvent was removed again. White solid 9.4 g was obtained by column chromatography with PE and CH2Cl2(volumetric ratio 4:1 ) as eluent with a yield of 69%. 1H NMR (500 MHz, CDC13) δ (ppm) 7.45 (dd, J = 8.1, 1.3 Hz, 2H), 7.32 - 7.27 (m, 2H), 7.11 (td, J = 8.5, 2.2 Hz, 1H), 6.84 - 6.77 (m, 1H), 4.10 (t, J = 6.4 Hz, 2H), 3.46 (t, J = 6.8 Hz, 2H), 2.53 (tt, J = 12.3, 3.1 Hz, 1H), 1.91 (dtd, J = 20.1, 13.4, 6.5 Hz, 8H), 1.58 - 1.44 (m, 6H), 1.38 - 1.23 (m, 9H), 1.08 (dt, J = 15.5, 6.5 Hz, 2H), 0.93 (t, J = 7.1 Hz, 3H).

[0031] Synthesis of compound 4: Into a 200 mL single necked flask was added compound 3 (2.0 g, 3.84 mmol), 5-bromo-1,3-benzenediol (0.33 g, 1.75 mmol), potassium carbonate (1.45 g, 10.5 mmol) and 35 mL of acetone. The reaction was purged with nitrogen three times and refluxed at 80 °C for 24 h. After cooling, the solvent was removed on a rotary evaporator and water was added. The mixture was extracted with DCM (3 x 50 mL), washed with water (3 x 80 mL), dried over anhydrous magnesium sulfate, filtered and the filtrate was collected and the solvent was removed again. Column chromatography was performed using PE and CH2Cl2 (2:1 by volume) as eluent to give 1.69 g of white solid in 91% yield. 1 H NMR (400 MHz, Chloroform-d) δ 7.43 (d, J = 7.3 Hz, 4H), 7.29 (s, 4H), 7.08 (td, J = 8.5, 1.9 Hz, 2H), 6.78 (t, J = 7.6 Hz, 2H), 6.64 (d, J = 2.0 Hz, 2H), 6.37 (s, 1H), 4.08 (t, J = 6.4 Hz, 4H), 3.92 (t, J = 6.3 Hz, 4H), 2.50 (t, J = 12.1 Hz, 2H), 1.96 - 1.77 (m, 16H), 1.56 - 1.40 (m, 11H), 1.38 - 1.18 (m, 19H), 1.06 (q, J = 11.2, 10.6 Hz, 4H), 0.90 (t, J = 6.9 Hz, 6H).

[0032] Synthesis of compound 5: Into a 200 mL single necked flask, compound 4 (0.8 g, 0.75 mmol), bis(pinacolato)diboron (0.29 g, 1.1 mmol), potassium acetate (0.37 g, 3.7 mmol), [l,l'-bis(diphenylphosphino)ferrocene]dichloropalladium (0.03 g, 0.04 mmol) and 30 mL of analytical grade toluene were added sequentially. The reaction was purged with nitrogen three times and then heated to reflux at 110 °C for 24 h. After cooling, the solvent was removed by rotary evaporation and water was added. The mixture was extracted with CH2Cl2(3 x 40 mL), washed with water (3 x 50 mL), dried over anhydrous magnesium sulfate, filtered and the filtrate was concentrated again. Column chromatography was performed using PE and CH2Cl2(1:1 by volume) as eluent to give 0.68 g of white solid with 81% yield. 1 H NMR (400 MHz, Chloroform-d) δ 7.35 (d, J = 7.2 Hz, 4H), 7.22 - 7.17 (m, 5H), 7.01 (td, J = 8.5, 2.1 Hz, 2H), 6.86 (d, J = 2.2 Hz, 2H), 6.70 (t, J = 8.1 Hz, 2H), 6.49 (t, J = 2.2 Hz, 1H), 4.00 (t, J = 6.5 Hz, 4H), 3.91 (t, J = 6.3 Hz, 4H), 2.48 - 2.38 (m, 2H), 1.88 - 1.70 (m, 17H), 1.53 - 1.35 (m, 17H), 1.24 - 1.13 (m, 22H), 1.06 - 0.89 (m, 5H), 0.83 (t, J = 6.9 Hz, 6H). 13 C NMR (101 MHz, Chloroform-d) δ 159.86, 147.37, 132.35, 128.60, 127.02, 123.52, 123.48, 123.44, 112.25, 109.43, 105.09, 83.81, 69.66, 67.75, 44.33, 37.38, 37.29, 34.28, 33.57, 32.22, 29.22, 29.10, 26.66, 25.83, 25.68, 24.83, 22.73, 14.14.

[0033] Synthesis of compound 6: In a 200 mL single necked flask, 1-bromo-3,5-difluorobenzene (1.0 g, 5.18 mmol), carbazole (0.79 g, 4.71 mmol), 9H-carbazole-3-carbonitrile (0.91 g, 4.71 mmol), cesium carbonate (3.07 g, 9.42 mmol) and 30 mL of dry N,N-dimethylformamide were added successively. The reaction system was purged with nitrogen three times and then heated at 120 °C for 24 h. After cooling, water was added and the mixture was extracted with CH2Cl2(3 x 50 mL), washed with water (3 x 60 mL), dried over anhydrous magnesium sulfate, filtered and the filtrate was concentrated using a rotary evaporator. Column chromatography was performed using PE and CH2Cl2(1:1 by volume) as eluent to give 0.91 g of white solid in 38% yield. 1 H NMR (400 MHz, Chloroform-d) δ 8.45 (s, 1H), 8.15 (t, J = 6.8 Hz, 3H), 7.95 (s, 1H), 7.81 (s, 1H), 7.76 - 7.69 (m, 2H), 7.56 - 7.40 (m, 8H), 7.34 (t, J = 7.4 Hz, 2H). 13 C NMR (101 MHz, Chloroform-d) δ 142.05, 141.07, 140.80, 140.12, 139.14, 129.66, 128.67, 127.89, 126.48, 125.48, 124.52, 123.97, 123.94, 123.89, 122.51, 110.41, 110.18, 109.45, 103.68.

[0034] Synthesis of compound 7: The synthesis method and procedure were the same as compound 5. Column chromatography was performed using PE and CH2Cl2(1:1 by volume) as eluent to give 0.87 g of white solid in 88% yield. 1 H NMR (400 MHz, Chloroform-d) δ 8.46 (s, 1H), 8.20 - 8.14 (m, 4H), 8.05 (s, 1H), 7.83 (s, 1H), 7.69 (d, J = 8.6 Hz, 1H), 7.46 (ddd, J = 29.7, 14.8, 7.2 Hz, 8H), 7.32 (t, J = 7.2 Hz, 2H), 1.37 (s, 12H). 13C NMR (101 MHz, Chloroform-d) δ 142.44, 141.49, 140.58, 139.16, 137.54, 133.12, 132.02, 129.36, 128.20, 127.56, 126.13, 125.30, 123.58, 122.23, 121.45, 120.74, 120.46, 120.35, 120.29, 110.47, 110.28, 109.52, 102.92, 84.61, 24.90.

[0035] Synthesis of compound (R / S)-8: The synthesis method and procedure were the same as compound 4, (R / S)-3,3'-dibromo-5,5',6,6',7,7',8,8'-octahydrobinol was added respectively, PE and CH2Cl2(volume ratio 3:1) were used as eluent, column chromatography was used for separation to get yellow sticky substance, (R)-8 was 2.68 g; (S)-8 was 2.66 g, the yield was 91% and 90% respectively. (R)-8: 1 H NMR (400 MHz, Chloroform-d) δ 7.43 (d, J = 7.5 Hz, 4H), 7.28 (d, J = 6.6 Hz, 6H), 7.12 - 7.06 (m, 2H), 6.78 (t, J = 7.8 Hz, 2H), 4.00 (t, J = 6.5 Hz, 4H), 3.79 (q, J = 6.3 Hz, 2H), 3.67 (q, J = 6.1 Hz, 2H), 2.73 (d, J = 5.9 Hz, 4H), 2.50 (t, J = 12.0 Hz, 2H), 2.37 - 2.27 (m, 2H), 2.10 (dt, J = 11.1, 6.4 Hz, 2H), 1.90 (t, J = 13.8 Hz, 8H), 1.75 - 1.61 (m, 12H), 1.53 - 1.43 (m, 8H), 1.35 - 1.21 (m, 22H), 1.06 (q, J = 11.6 Hz, 8H), 0.90 (t, J = 6.9 Hz, 6H). 13C NMR (101 MHz, Chloroform-d) δ 151.05, 150.09, 149.98, 147.37, 143.03, 142.88, 140.58, 140.43, 136.32, 134.62, 132.74, 132.40, 132.35, 128.59, 128.56, 127.02, 123.51, 123.47, 123.43, 122.97, 122.86, 114.24, 109.49, 109.46, 72.20, 69.64, 44.33, 34.28, 33.57, 32.22, 29.78, 29.23, 29.09, 27.45, 26.66, 25.35, 25.33, 22.77, 22.73, 14.14.(S)-8: 1 H NMR (400 MHz, Chloroform-d) δ 7.43 (d, J = 7.5 Hz, 4H), 7.28 (d, J = 6.6 Hz, 6H), 7.12 - 7.06 (m, 2H), 6.78 (t, J = 7.8 Hz, 2H), 4.00 (t, J = 6.5 Hz, 4H), 3.79 (q, J = 6.3 Hz, 2H), 3.67 (q, J = 6.1 Hz, 2H), 2.73 (d, J = 5.9 Hz, 4H), 2.50 (t, J = 12.0 Hz, 2H), 2.32 (dt, J = 16.8, 6.1 Hz, 2H), 2.10 (dt, J = 17.1, 6.1 Hz, 2H), 1.90 (t, J = 13.8 Hz, 8H), 1.67 (dp, J = 24.7, 6.8 Hz, 12H), 1.48 (td, J = 13.1, 8.2 Hz, 8H), 1.30 (dq, J = 18.7, 6.0 Hz, 22H), 1.06 (q, J = 12.5, 11.9 Hz, 8H), 0.90 (t, J = 6.9 Hz, 6H). 13 C NMR (101 MHz, Chloroform-d) δ 151.05, 150.09, 149.98, 147.37, 143.03, 142.88, 140.58, 140.43, 136.32, 134.62, 132.74, 132.40, 132.35, 128.59, 128.56, 127.02, 123.51, 123.47, 123.43, 122.97, 122.86, 114.24, 109.49, 109.46, 72.20, 69.64, 44.33, 34.28, 33.57, 32.22, 29.78, 29.23, 29.09, 27.45, 26.66, 25.35, 25.33, 22.77, 22.73, 14.14.

[0036] Synthesis of compound (R / S)-2LC: The synthesis method and procedure were the same as compound 1, (R / S)-8 and compound 7 were added respectively, eluted with PE and EA (volume ratio 8:1) to separate by column chromatography to obtain white solid, (R)-2LC was 0.43 g; (S)-2LC was 0.42 g, the yield was 53% and 52% respectively. (R)-2LC: 1 H NMR (400 MHz, Chloroform-d) δ 8.42 (s, 2H), 8.13 (d, J = 7.8 Hz, 6H), 8.00 (s, 2H), 7.89 (s, 2H), 7.70 - 7.61 (m, 4H), 7.57 - 7.45 (m, 10H), 7.44 - 7.27 (m, 16H), 7.24 (d, J = 8.1 Hz, 4H), 6.95 - 6.88 (m, 2H), 6.37 (t, J = 8.1 Hz, 2H), 3.67 - 3.61 (m, 2H), 3.57 - 3.42 (m, 6H), 2.88 - 2.77 (m, 4H), 2.55 - 2.42 (m, 4H), 2.37 - 2.29 (m, 2H), 1.91 (t, J = 12.8 Hz, 8H), 1.73 (ddd, J = 23.7, 11.4, 5.8 Hz, 8H), 1.51 - 1.43 (m, 4H), 1.27 (q, J = 14.0, 13.0 Hz, 25H), 1.13 - 0.96 (m, 9H), 0.93 - 0.84 (m, 10H). TOF-MS (ESI) m / z calcd for C 140 H 132 F4N6O4: 2038.63; [M+Na] + found: 2061.963. (S)-2LC: 1H NMR (400 MHz, Chloroform-d) δ 8.42 (s, 2H), 8.13 (d, J = 7.8 Hz, 6H), 8.01 (s, 2H), 7.89 (s, 2H), 7.70 - 7.62 (m, 4H), 7.57 - 7.46 (m, 10H), 7.37 (p, J = 7.6 Hz, 10H), 7.31 - 7.26 (m, 6H), 7.24 (d, J = 8.0 Hz, 4H), 6.91 (t, J = 8.4 Hz, 2H), 6.37 (t, J = 7.7 Hz, 2H), 3.68 - 3.61 (m, 2H), 3.56 - 3.42 (m, 6H), 2.89 - 2.78 (m, 4H), 2.54 - 2.41 (m, 4H), 2.33 (dt, J = 16.9, 6.1 Hz, 2H), 1.91 (t, J = 13.6 Hz, 8H), 1.73 (ddd, J = 23.5, 11.2, 6.0 Hz, 8H), 1.46 (td, J = 13.2, 3.0 Hz, 4H), 1.33 - 1.20 (m, 25H), 1.04 (dq, J = 22.8, 8.7, 7.4 Hz, 9H), 0.92 - 0.83 (m, 10H). TOF-MS (ESI) m / z calcd for C 140 H 132 F4N6O4: 2038.63; [M+Na] + found: 2061.762.

[0037] Synthesis of compound (R / S)-4LC: The synthesis method and procedure were the same as compound (R / S)-2LC, (R / S)-8, compound 5 and compound 7 were added respectively, and the eluent was PE and EA (volume ratio 10:1), and the white solid was separated by column chromatography, (R)-4LC was 0.45 g; (S)-4LC was 0.47 g, the yield was 32% and 33% respectively. 1H NMR (400 MHz, Methylene Chloride-d2) δ 8.36 (dd, J = 1.5, 0.7 Hz, 1H), 8.06 (tt, J = 7.6, 1.0 Hz, 3H), 7.95 (t, J = 1.7 Hz, 1H), 7.85 (t, J = 1.8 Hz, 1H), 7.63 - 7.57 (m, 2H), 7.54 - 7.49 (m, 4H), 7.43 (ddd, J = 8.4, 7.2, 1.2 Hz, 1H), 7.35 - 7.25 (m, 11H), 7.22 - 7.15 (m, 11H), 7.00 - 6.95 (m, 3H), 6.92 - 6.84 (m, 2H), 6.68 (ddd, J = 9.1, 7.6, 1.9 Hz, 2H), 6.63 (d, J = 2.3 Hz, 2H), 6.48 - 6.39 (m, 2H), 6.31 (t, J = 2.2 Hz, 1H), 3.93 (t, J = 6.5 Hz, 4H), 3.86 (t, J = 6.4 Hz, 4H), 3.71 - 3.33 (m, 8H), 3.17 (q, J = 6.3 Hz, 1H), 2.72 (dd, J = 16.6, 5.3 Hz, 4H), 2.45 - 2.32 (m, 6H), 2.25 - 2.16 (m, 2H), 1.80 (d, J = 11.3 Hz, 18H), 1.75 - 1.62 (m, 14H), 1.44 - 1.35 (m, 18H), 1.28 - 1.14 (m, 42H), 0.99 (qd, J = 14.9, 13.2, 10.0 Hz, 15H), 0.82 (ddd, J = 7.2, 5.8, 1.3 Hz, 12H). TOF-MS (ESI) m / z calcd for C 173 H 195 F8N3O8: 2594.48; [M+Na] + found: 2617.768. (S)-4LC: 1H NMR (400MHz, Methylene) Chloride-d2)δ8.36(d,J=1.6Hz,1H),8.09–8.04(m,3H),7.95(t,J=1.8Hz,1 H),7.85(t,J=1.7Hz,1H),7.63–7.58(m,2H),7.55–7.50(m,4H),7.46–7.41(m ,1H),7.37–7.25(m,11H),7.23–7.15(m,11H),7.00–6.95(m,3H),6.88(dtd,J =11.1,8.6,2.3Hz,2H),6.71–6.62(m,4H),6.43(dt,J=15.7,8.5Hz,2H),6.31 (t,J=2.3Hz,1H),3.94(t,J=6.5Hz,4H),3.86(t,J=6.4Hz,4H),3.72–3.51(m, 6H),3.46–3.37(m,2H),3.17(d,J=8.5Hz,1H),2.78–2.68(m,4H),2.45–2.31( m,6H),2.20(dd,J=16.8,6.5Hz,2H),1.84–1.59(m,32H),1.44–1.33(m,18H), 1.29–1.14(m,42H),1.07–0.92(m,15H),0.84–0.80(m,12H).TOF-MS(ESI)m / z calcd for C 173 H 195 F8N3O8: 2594.48; [M+Na] + Found: 2617.657.

[0038] Example 2

[0039] The compounds (R)-2LC and (R)-4LC from Example 1 of this invention, along with the common host material mCPCN, were dissolved in toluene to prepare a 10... -5 Solution M was tested, and its UV-Vis absorption and photoluminescence spectra were measured. Figure 1 It can be seen that the UV-Vis absorption spectrum of the compound in toluene solution exhibits approximately two types of absorption peaks: a strong absorption peak at a short wavelength (280 nm) mainly attributed to the π-π* transition absorption of the molecule; and a long wavelength (330 nm) absorption peak attributed to the intramolecular charge transfer (ICT) transition absorption peak, with (R)-2LC and (R)-4LC absorption peaks at 283, 326, and 339 nm, respectively, consistent with the absorption peaks of the host material mCPCN. Furthermore, from... Figure 1It can be seen that the emission peaks of (R)-2LC and (R)-4LC are 348 nm and 364 nm, which are consistent with the emission peak of the host material mCPCN. This shows that the introduction of octahydrobinaphthyl chiral unit and two liquid crystal units (or four liquid crystal units) has no effect on the absorption and emission of the compound, and the absorption and emission peaks of the compound depend on the absorption and emission peaks of the light-emitting host unit.

[0040] Example 3

[0041] The compounds (R)-2LC, (R)-4LC and mCPCN in Example 1 of the application were prepared into 10 -5 mol / L toluene solution, and then placed in a low-temperature test cell. After vacuumizing for 15 minutes, liquid nitrogen was slowly added until the temperature dropped to 77K, and then the low-temperature fluorescence and phosphorescence spectra were tested. The excitation light source was a 300 nm flicker xenon lamp, as shown in Figure 2 According to the tangent of the peak position in the spectrum, the S1 of compounds (R)-2LC and (R)-4LC was 3.69 eV and 3.65 eV, respectively, and the T1 was 2.96 eV and 3.06 eV, respectively. This is not much different from the S1 of 3.71 eV and the T1 of 3.15 eV of the host material mCPCN. This shows that the introduction of octahydrobinaphthyl chiral unit and two liquid crystal units (or four liquid crystal units) has little effect on the reduction of the triplet state energy level of the compound, and the synthesized compounds (R / S)-2LC and (R / S)-4LC can be used as host materials for light-emitting devices.

[0042] Example 4

[0043] The compounds (R)-2LC and (R)-4LC in Example 1 of the application were subjected to thermal gravimetric analysis to study the thermal stability of the compounds. As shown in Figure 3 , the temperatures at which the compounds (R)-2LC and (R)-4LC lost 5% of their weight were 391°C and 387°C, respectively, both showing very good thermal stability, which is conducive to the preparation of light-emitting devices.

[0044] Example 5

[0045] The transient fluorescence spectra of the compounds (R)-2LC and (R)-4LC in Example 1 of the application in the pure thin film state were characterized, and the excitation light source was EPL 277 nm and the detection wavelength was 372 nm. As shown in Figure 4 , the lifetimes of compounds (R)-2LC and (R)-4LC were 3.3 ns and 6.4 ns, respectively, both of which were fluorescent materials.

[0046] Example 6

[0047] The compounds (R)-2LC and (R)-4LC in Example 1 of the application were tested for DSC curves, and theFigure 5 (a) It is known that the phase transition temperature of both compounds is 112°C. In addition, compound (R)-4LC is heated, which gradually changes from solid to melt, and then to flow, as shown in Figure 5 (b) During the slow cooling process, obvious birefringence is observed, showing a focal conic fan texture, which is a typical smectic phase liquid crystal.

[0048] Example 7

[0049] The compound (R / S)-4LC in Example 1 of the present application is dissolved in toluene solution (10 mg / mL), and the circular dichroism absorption spectrum and circularly polarized luminescence spectrum of the spin-coated film (20 uL of liquid is taken and spun at 1500 r / min) and the drop-coated film (20 uL of liquid is dropped on the substrate) are tested. As shown in Figure 6 , the spin-coated film and the toluene solution have no CPL signal, while the drop-coated film has a very strong CPL signal, and the CPL spectra of the two pairs of enantiomers of (R / S)-4LC show mirror image characteristics. The luminescence asymmetry factor g lum of (R / S)-4LC at the luminescence peak 370 nm is -0.52 and 0.47, respectively. In the solution, the luminescence asymmetry factor g lum is very small, which is lower than the detection value of the detection equipment, so there is no CPL signal. The spin-coated film is formed by spreading the liquid on the substrate by centrifugal force, which destroys the ordered arrangement of (R / S)-4LC molecules, and the chiral signal of the molecules itself cannot be detected by the detection equipment, so it also shows no CPL signal. (R / S)-4LC molecular structure contains not only octahydrobinaphthyl chiral units, but also 4 liquid crystal elements, which makes the natural evaporation process of the drop-coated film naturally ordered arrangement of molecules along a specific direction, which amplifies the chiral signal of individual molecules, and the macroscopic performance is that the drop-coated film can detect a very strong CPL signal, and the CPL spectra of the two pairs of enantiomers of (R / S)-4LC show mirror image characteristics.

[0050] Example 8

[0051] The compound (R / S)-4LC in Example 1 of the present application is dissolved in toluene to obtain solutions of different concentrations (1, 5, 10, 20, 40, 60, 80 mg / mL), and the circular dichroism absorption spectrum and circularly polarized luminescence spectrum of the drop-coated films of different concentrations (20 uL of liquid is dropped) are tested. As shown in Figure 7 , with the increase of the concentration, the CD and CPL signals increase obviously, and the two pairs of enantiomers of (R / S)-4LC show mirror image characteristics. At a concentration of 40 mg / mL, the g lumThe values ​​were -0.71 and 0.73 (at 370 nm), respectively, which is the highest reported value for the luminescence asymmetry factor of this material. As the concentration continued to increase, the excessive aggregation of molecules hindered the orderly arrangement of molecules during the natural evaporation of the droplet film, resulting in a weakening of the CD and CPL signals.

[0052] Example 9

[0053] Using compound (R / S)-4LC from Example 1 of this invention as the chiral host material, chiral signal transmission to inorganic achiral guest luminescent material quantum dots (QDs) (630nm wavelength cadmium-based red quantum dots; specific materials are required in the examples) was achieved for the first time. Figure 8 As shown in (a), the absorption of the inorganic achiral guest quantum dots occurs within the emission region of the (R)-4LC chiral host material, and the spectra of the two overlap, enabling efficient energy transfer. To further verify the chiral energy transfer mechanism from the chiral host to the achiral guest, (R)-4LC (1 mg / mL toluene solution) and different doping ratios (wt%) were used. Figure 8 Thin films were prepared using a quantum dot droplet coating method, and their photoluminescence, CD, and CPL spectra were measured. (See figures below.) Figure 8 As shown in (b, c, d), with the increase of the quantum dot doping ratio, the energy of the (R)-4LC chiral host material is transferred to the achiral guest material quantum dot. At a doping ratio of 60 wt%, the energy of (R)-4LC is almost completely transferred to the inorganic guest material quantum dot. It can also be seen from the CPL spectrum that with the increase of the doping ratio, the achiral guest material quantum dot also begins to have a chiral signal. At a doping ratio of 60 wt%, the chiral signal of the chiral host material (R)-4LC (at 370 nm) is almost completely transferred to the quantum dot (at 630 nm).

[0054] Example 10

[0055] The chiral liquid crystal host material (R)-4LC in the embodiment 1 of the present application and inorganic non-chiral quantum dots (QD) are used as the device light-emitting layer, and the application of the organic chiral host material to the circularly polarized organic light-emitting diode (CP-OLED) of the inorganic non-chiral guest material is realized for the first time. The CP-OLED light-emitting device is prepared by using the compound (R)-4LC as the host material of the device light-emitting layer by the solution processing method, and the device structure is: ITO / PEDOT:PSS (35 nm) / (R)-4LC: 60 wt% QD / DPEPO (9 nm) / TmPyPB (45 nm) / LiF (0.5 nm) / Al (120 nm). In the device structure, the PEDOT:PSS is spin-coated on the ITO anode substrate as the hole transport layer, the DPEPO is the hole blocking layer, the TmPyPB is the electron transport layer, and the Liq and Al are the cathode. The (R)-4LC is the host material of the light-emitting layer, and the inorganic material quantum dot QD is the guest material of the light-emitting layer. The light-emitting layer (organic R-4LC and inorganic QD) is prepared by the drop-coating film method to obtain the circularly polarized organic light-emitting diode for the first time. The device structure and performance are shown in Figure 9 The EL is 636 nm, the EL spectrum of the device is close to the PL spectrum (630 nm) of the inorganic non-chiral light-emitting guest material quantum dot, and the emission peak of the chiral liquid crystal host material R-4LC is not seen, which indicates that the EL spectrum of the device is from the intrinsic emission of the light-emitting guest material quantum dot, and the complete energy transfer occurs between the host and the guest of the device. The color coordinates are CIE (0.29, 0.60), the half peak width FWHM is 42, the maximum external quantum efficiency EQE max is 3%, the g EL of the circularly polarized electroluminescent device is -0.01 (636 nm), which is the first high-efficiency CP-OLED prepared from the organic chiral host material to the inorganic non-chiral guest material.

[0056] Embodiment 11

[0057] The compound (R / S)-4LC in the embodiment 1 of the present application is applied to other organic non-chiral light-emitting guest materials. As shown in Figure 10 , the organic non-chiral light-emitting guest material whose absorption is in the emission region of the chiral liquid crystal host material (R / S)-4LC is selected, and the CP-OLED device is prepared by using the solution processing method. The device structure is: ITO / PEDOT:PSS (35 nm) / (R / S)-4LC: 60 wt% QD / DPEPO (9 nm) / TmPyPB (45 nm) / LiF (0.5 nm) / Al (120 nm). In the device structure, the PEDOT:PSS is spin-coated on the ITO anode substrate as the hole transport layer, the DPEPO is the hole blocking layer, the TmPyPB is the electron transport layer, and the Liq and Al are the cathode. The (R / S)-4LC is the host material of the light-emitting layer, and the inorganic material quantum dot QD is the guest material of the light-emitting layer. The light-emitting layer (organic R-4LC and inorganic QD) is prepared by the drop-coating film method to obtain the circularly polarized organic light-emitting diode for the first time. The device structure and performance are shown in .In toluene solution, the emission peak of achiral phosphorescent guest material tris[2-(p-tolyl)pyridyl]iridium(III) Ir(mppy)3 is 516 nm, the emission peak of bis[2-(1-isoquinolyl-N)phenyl-C](2,4-pentanedionato-O2,O4)iridium(III) Ir(piq)2acac is 630 nm, the emission peak of achiral TADF guest material 10-(4-(4,6-diphenyl-1,3,5-triazol-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroacridine DMAc-TRZ is 501 nm, and the emission peak of achiral boron-nitrogen guest material BN5 (Advanced Materials, 2022, 34, 2105080.

[0058] 499 nm. According to the appropriate doping ratio between the respective host-guest, the ITU films were doped into the chiral liquid crystal host material (R / S)-4LC (10 mg / mL toluene solution), and their CPL spectra were tested. It can be seen from Figure 10 (c, d, e, f) that the chiral energy of the emission peak (370 nm) of the chiral liquid crystal host material (R / S)-4LC is completely transferred to the organic achiral luminescent guest material Ir(mppy)3, Ir(piq)2acac, and DMAC-TRZ, and very strong CPL signals are detected at the respective emission peak positions. The chiral BN5 also detects stronger CPL signals (compared with its intrinsic chiral CPL signal Advanced Materials, 2022, 34, 2105080) at the respective emission peak positions, and the CPL signals of the two pairs of enantiomers exhibit mirror image characteristics. This further indicates that the overlap of the absorption of the achiral guest and the emission of the chiral host material (R / S)-4LC, and the appropriate doping ratio between the host and the guest, can completely transfer the chiral energy of the chiral host material (R / S)-4LC to the achiral guest material, thereby emitting CPL signals at the emission peak position of the guest material, and the strength of the CPL signal depends on the chiral energy of the chiral host material

[0059] The ordered arrangement of molecules during the drop-film evaporation process of (R / S)-4LC at a specific concentration. This also indicates that the chiral energy transfer of the chiral liquid crystal host material (R / S)-4LC and the like has universality, and can be transferred not only to inorganic achiral quantum dot luminescent materials, but also to organic achiral luminescent materials, which has great commercial application value.

[0060] Example 12

[0061] The application of compound (R)-4LC from Example 1 of this invention in circularly polarized organic light-emitting diodes (CP-OLEDs) is illustrated. Using compound (R)-4LC as the host material for the light-emitting layer, CP-OLED devices were fabricated using a solution processing method. The device structure was: ITO / PEDOT:PSS (40nm) /

[0062] (R)-4LC: xwt% Ir(mppy)3 (30nm) / DPEPO (9nm) / TmPyPB (45nm) / LiF (0.5nm) / Al (120nm). In this device structure, PEDOT:PSS is spin-coated onto the ITO anode substrate as a hole transport layer, (R)-4LC is the host material of the light-emitting layer, Ir(mppy)3 is the guest material of the light-emitting layer, DPEPO is the hole blocking layer, TmPyPB is the electron transport layer, and LiQ and Al are used as cathodes. Figure 11 As shown, the EL is 522 nm, which is the PL emission peak of the guest material Ir(mppy)3, with color coordinates CIE(0.32, 0.61) and a maximum external quantum efficiency of 7.4%.

[0063] Example 13

[0064] The application of compound (R)-4LC from Example 1 of this invention in circularly polarized organic light-emitting diodes (CP-OLEDs). Using compound (R)-4LC as the host material of the emitting layer, CP-OLED devices were fabricated using a solution processing method. The device structure was: ITO / PEDOT:PSS (40nm) / (R)-4LC:xwt%DMAC-TRZ (30nm) / DPEPO (9nm) / TmPyPB (45nm) / LiF (0.5nm) / Al (120nm). In this device structure, PEDOT:PSS was spin-coated onto the ITO anode substrate as a hole transport layer, (R)-4LC was the host material of the emitting layer, DMAC-TRZ was the guest material of the emitting layer, DPEPO was the hole blocking layer, TmPyPB was the electron transport layer, and LiF and Al were used as cathodes. Figure 12 As shown, the EL is 512 nm, which is the PL emission peak of the guest material DMAC-TRZ, with color coordinates of CIE (0.25, 0.51) and a maximum external quantum efficiency of 16.4%.

[0065] Although the invention has been described in conjunction with preferred embodiments, the invention is not limited to the above embodiments, and it should be understood that the appended claims summarize the scope of the invention. Guided by the inventive concept, those skilled in the art should recognize that any modifications made to the various embodiments of the invention will be covered by the spirit and scope of the claims.

Claims

1. A type of chiral liquid crystal host material, characterized in that, The chiral liquid crystal host material has the following structure: 。 2. A method for preparing a chiral liquid crystal host material according to claim 1, characterized in that: The preparation method is as follows: using chiral octahydrobinazone or chiral binazone as the chiral building source, 9,9'-(1,3-phenyl)bis-9H-carbazole (mCP) or 9-(3-(9H-carbazole-9-yl)phenyl)-9H-carbazole-3-nitrile (mCPCN) is connected in a non-conjugated manner to construct a chiral liquid crystal host material.

3. An application of the chiral liquid crystal host material according to claim 1, characterized in that, The chiral liquid crystal host material is used to prepare organic electroluminescent devices.

4. The application of the chiral liquid crystal host material according to claim 3, characterized in that, The chiral liquid crystal host material is used to prepare circularly polarized organic light-emitting diodes via solution processing drop-coating thin film method.

5. The application of the chiral liquid crystal host material according to claim 4, characterized in that, The chiral liquid crystal host material and the inorganic achiral quantum dot luminescent material or the organic achiral luminescent material are used as the luminescent layer to prepare a circularly polarized organic light-emitting diode.

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