Blue light materials based on spirofluorene indole isomers and their applications

Abstract

The present invention belongs to the technical field of organic electroluminescent materials, and particularly relates to a blue light material based on spirofluorene indole isomers and its application. A series of novel blue light materials are constructed by combining a tert-butyl spirofluorene unit with indole as an electron donor and a triazine derivative as an electron acceptor. The combination of the tert-butyl spirofluorene unit and indole forms a new donor with stronger rigidity, which increases the molecular rigid structure, is beneficial to inhibiting the non-radiative transition of the molecule, and obtaining a high-efficiency fluorescent material. Using this type of novel blue light material as the luminescent layer dopant, a solution-processable electroluminescent device is prepared, and a relatively high maximum external quantum efficiency is obtained. The present invention details the relationship between the molecular structure and properties, which is of great significance for constructing highly efficient blue fluorescent materials.

Description

Technical Field

[0001] The invention belongs to the technical field of organic electroluminescent materials, and particularly relates to a blue light material based on spirofluorene indole isomers and application thereof. Background Art

[0002] Currently, organic light-emitting diodes (OLEDs) have been widely used in next-generation displays and solid-state lighting based on their desirable properties such as low cost, flexibility, and light weight. With great progress in academia and industry, the performance of green and red devices, including efficiency and lifetime, has reached commercial levels, fully meeting consumer expectations, while blue OLEDs with moderate efficiency are considered a considerable obstacle to improving the lifetime of full-color OLEDs due to the inherent instability of their devices. In order to break through this bottleneck of blue OLEDs, researchers have made great efforts to explore blue OLEDs and optimize the device structure. Successive improvements have been obtained using the following three generations of materials: first-generation fluorescence, second-generation phosphorescence, and third-generation thermally activated delayed fluorescence (TADF). Blue phosphorescent and TADF materials still face severe challenges in view of the high cost of noble metal-containing phosphorescent materials and the severe efficiency degradation caused by the long lifetime of triplet excitons of blue TADF materials. To date, blue fluorescent materials that exhibit moderate efficiency and excellent stability are still favored by commercial blue OLEDs.

[0003] In order to construct excellent fluorescent OLEDs that meet practical needs, donor-acceptor (DA)-type blue light-emitting materials based on polycyclic aromatic hydrocarbons (PAHs) are highly anticipated for their considerable optical properties as well as bipolar charge carrier transport properties, which are beneficial for obtaining balanced carrier transport capabilities and stable operation of OLED devices. In addition, by selecting appropriate D / A units, the electronic interactions and charge transfer efficiency in DA-type PAHs materials can be precisely controlled to obtain the desired emission color. Among all the organic units for constructing OLED materials, spiro structures and their derivative compounds can naturally separate holes and electrons due to their good thermal stability and unique orthorhombic rigid structure, which is beneficial for minimizing the singlet-triplet splitting energy (ΔE ST ). The most classic aromatic spiro unit is 9,9'-bifluorene (SBF), which was first reported in 1930. The research on aromatic spiro compounds is closely related to the development of organic semiconductors; currently, the relationship between the structure and properties of spiro compounds is becoming clearer and clearer, which has attracted widespread attention in the materials industry. Summary of the invention

[0004] To obtain an efficient and stable blue light material, the present invention combines a tert-butyl spirofluorene unit with an indole unit as an electron donor and a triazine derivative as an electron acceptor to construct a series of novel blue light materials. In the technical solution of the present invention, the spirofluorene unit is a good electron-donating unit. The orthogonal structure caused by its spiro configuration can not only reduce the intermolecular interaction, reduce the molecular packing, but also naturally separate holes and electrons, which is beneficial to minimizing ΔE ST . On the other hand, introducing tert-butyl groups at different positions of the spirofluorene donor unit can increase the solubility of the molecule. Combining it with indole forms a new donor with stronger rigidity, obtaining a relatively planar structure while increasing the molecular rigidity, which is beneficial to suppressing the non-radiative transition of the molecule and achieving excellent device performance. In addition, the present invention also systematically studied the influence of the introduction of methyl groups, which results in a larger steric hindrance between the molecular donor and acceptor, on the photophysical properties of the material due to different dihedral angles between the spirofluorene donor and the triazine acceptor, which is of great significance for exploring efficient blue light materials.

[0005] To achieve the above technical objectives, the present invention synthesizes a class of fluorescent materials with a rigid unit of spirofluorene-fused indole isomers as an electron donor and a triazine derivative as an electron acceptor. The fluorescent material has the following structure:

[0006]

[0007] The present invention also provides an application of the above blue light material based on spirofluorene-fused indole isomers. The blue light material based on spirofluorene-fused indole isomers is used as a luminescent layer dopant, and an organic electroluminescent device is prepared by solution processing.

[0008] Furthermore, the structure of the organic electroluminescent device is ITO / PEDOT:PSS / mCPCN:dopant:TAPC / TmPyPB / LiF / Al; where PEDOT:PSS is the hole injection layer, mCPCN:dopant:TAPC is the luminescent layer material, TmPyPB is the electron transport layer, and LiF / Al is the cathode.

[0009] The preparation method of the luminescent layer of the organic electroluminescent diode is: dissolving the blue light material based on spirofluorene-fused indole isomers in a chlorobenzene solution, blending it with mCPCN and TAPC, and then spin-coating it on the surface of the hole injection layer, and forming the luminescent layer of the organic electroluminescent diode after annealing treatment.

[0010] Furthermore, the mass doping ratio of the blue light material based on spirofluorene-fused indole isomers, mCPCN, and TAPC is m mCPCN :m dopant :m TAPC =1-4:2:7; the preferred mass ratio is 3-4:2:7.

[0011] Furthermore, the mass concentration of the blue light material based on spirofluorene indole isomers in chlorobenzene solution is 1-10 mg / ml, preferably 10 mg / ml.

[0012] Furthermore, the spin coating speed is 1500-1800 r / s, preferably 1700 r / s.

[0013] Furthermore, the spin coating thickness is 55 nm.

[0014] Furthermore, the annealing temperature is 70-90 °C, preferably 80 °C, and the annealing time is 15 min.

[0015] Compared with the prior art, the beneficial effects brought by the technical solution of the present invention are as follows: 1. In this invention patent, tert-butyl is introduced into the spirofluorene unit and then combined with indole to form two isomers with stronger rigidity. While increasing the molecular solubility, non-radiative transitions of molecules are inhibited. Through this construction method, a series of blue light materials are obtained, and their maximum emission wavelength is in the range of 430-490 nm; 2. The introduction of phenyl bridge and methyl inhibits the vibration of molecules. More importantly, it plays a role in adjusting the dihedral angle. As the dihedral angle between the donor and acceptor increases, the emission wavelength of the molecule undergoes a significant blue shift, and the full width at half maximum decreases significantly, which is beneficial to improving the color purity of the material and constructing highly efficient blue light materials; 3. Using this type of D-A type blue light material of spirofluorene indole as the light-emitting layer, a highly efficient solution-processable electroluminescent device can be obtained, and its maximum external quantum efficiency is relatively high. Brief Description of the Drawings

[0016] Figure 1 It is the ultraviolet-visible light absorption spectrogram of Compounds 1-6 prepared in Example 1 of the present invention in toluene solution.

[0017] Figure 2 It is the photoluminescence spectrogram of Compounds 1-6 prepared in Example 1 of the present invention in toluene solution.

[0018] Figure 3 It is the photoluminescence spectrogram of Compounds 1-6 prepared in Example 1 of the present invention in 10% doped PMMA film.

[0019] Figure 4 It is the photoluminescence spectrogram of Compound 1 prepared in Example 1 of the present invention in six solutions of n-hexane, toluene, n-butyl ether, chloroform, tetrahydrofuran, ethyl acetate and dichloromethane.

[0020] Figure 5 It is the photoluminescence spectrogram of Compound 2 prepared in Example 1 of the present invention in six solutions of n-hexane, toluene, n-butyl ether, chloroform, tetrahydrofuran, ethyl acetate and dichloromethane.

[0021] Figure 6Photoluminescence spectra of Compound 3 prepared in Example 1 of the present invention in six solutions: n - hexane, toluene, n - butyl ether, chloroform, tetrahydrofuran, ethyl acetate, and dichloromethane.

[0022] Figure 7 Photoluminescence spectra of Compound 4 prepared in Example 1 of the present invention in six solutions: n - hexane, toluene, n - butyl ether, chloroform, tetrahydrofuran, ethyl acetate, and dichloromethane.

[0023] Figure 8 Photoluminescence spectra of Compound 5 prepared in Example 1 of the present invention in six solutions: n - hexane, toluene, n - butyl ether, toluene, chloroform, tetrahydrofuran, ethyl acetate, and dichloromethane.

[0024] Figure 9 Photoluminescence spectra of Compound 6 prepared in Example 1 of the present invention in six solutions: n - hexane, toluene, n - butyl ether, chloroform, tetrahydrofuran, ethyl acetate, and dichloromethane.

[0025] Figure 10 Transient lifetime curves of Compounds 1 - 6 prepared in Example 1 of the present invention in toluene solution.

[0026] Figure 11 Electroluminescence spectrum of Compound 3 prepared in Example 1 of the present invention.

[0027] Figure 12 Comparative electroluminescence spectra of Compounds 3 and 4 prepared in Example 1 of the present invention. Detailed implementation manners

[0028] The following specific implementation cases are intended to further illustrate the present invention, but these specific implementation manners do not limit the protection scope of the present invention in any way.

[0029] Example 1

[0030] The synthesis scheme of the blue - light material based on tert - butyl spirofluorene - indole is as follows:

[0031]

[0032]

[0033] Synthesis of Compound SM1

[0034] 2-Bromodiphenylamine (10.0 g, 40.3 mmol), 1-tert-butyl-4-iodobenzene (12.6 g, 48.6 mmol), palladium acetate (0.456 g, 2.0 mmol), tri-tert-butylphosphine tetrafluoroborate (1.5 g, 5.0 mmol), sodium tert-butoxide (5.9 g, 60.1 mmol) and 125 mL of analytically pure toluene were added to a 500 mL single-mouth bottle in sequence, and the mixture was heated to 110° C. and refluxed for 24 hours under nitrogen protection. The mixture was cooled to room temperature, toluene was removed by rotary evaporation under reduced pressure, extracted with dichloromethane (3×50 mL), washed with water three times, dried over anhydrous magnesium sulfate, filtered, the filtrate was collected, the solvent was dried by rotary evaporation, and 12.3 g of colorless oily liquid was obtained by column chromatography with petroleum ether as eluent, with a yield of 80%. 1 HNMR(400MHz, CDCl3)δ7.63(d,J=8.0Hz,2H),7.50–7.34(m,1H),7.30(d,J=8.3H z,1H),7.23–7.18(m,3H),7.09(t,J=7.6Hz,1H),6.95–6.91(m,5H),1.30(s,9H).

[0035] Synthesis of compounds SM2 and SM3

[0036] Add 35mL of dry tetrahydrofuran to a 250mL double-necked bottle, dissolve compound SM1 (6.0g, 15.8mmol), pass nitrogen, move into a -78℃ low-temperature tank, stir for 0.5 hours, slowly drop n-butyl lithium (8.8mL, 22.1mmol), and stir for 1 hour. Subsequently, dissolve 2-bromo-9-fluorenone (4.9g, 18.9mmol) in dry tetrahydrofuran and slowly drop into the system, stir for 1 hour and then move out of the low-temperature tank, and react at room temperature overnight. After the reaction is completed, add water to quench, extract with dichloromethane (3×50mL), wash three times with water, dry with anhydrous magnesium sulfate, filter and collect the filtrate, and spin dry the solvent. Prepare glacial acetic acid: hydrochloric acid (10:1) solution to dissolve the mixture in the bottle, and heat the mixture to 100℃ under nitrogen protection and reflux for 12 hours. The mixture was cooled to room temperature, extracted with dichloromethane (3×50 mL), washed three times with water, dried over anhydrous magnesium sulfate, filtered, the filtrate was collected, and the solvent was dried by spin drying. 4.4 g of a light yellow solid was obtained by column chromatography using petroleum ether as the eluent, with a yield of 51%. 11H NMR (400 MHz, DMSO) δ 8.03–7.95 (m, 2H), 7.79 (s, 2H), 7.63 (s, 2H), 7.56 (d, J = 7.4 Hz, 1H), 7.49 (s, 3H), 7.36 (d, J = 6.8 Hz, 2H), 7.00 (dd, J = 18.3, 9.2 Hz, 2H), 6.58 (d, J = 3.0 Hz, 1H), 6.23 (d, J = 15.3 Hz, 4H), 1.43 (s, 3H), 0.90 (s, 6H).

[0037] Synthesis of Compounds SM4 and SM5

[0038] Add the mixture of SM2 and SM3 (1.8 g, 3.3 mmol), bis(pinacolato)diboron (1.3 g, 5.0 mmol), 1,1'-bis(diphenylphosphino)ferrocene dichloropalladium (0.1 g, 0.2 mmol), potassium acetate (0.6 g, 6.6 mmol) and 30 mL of analytical pure 1,4-dioxane into a 100 mL single-necked flask. After purging with nitrogen, reflux at 110 °C for 12 h. After the reaction is completed, cool to room temperature, rotary evaporate to remove the solvent, add water and extract with dichloromethane (3 × 50 mL), wash three times with water, dry over anhydrous magnesium sulfate, filter and collect the filtrate, and rotary evaporate the solvent. Using petroleum ether and dichloromethane (volume ratio 6:1) as the eluent, separate by column chromatography to obtain 1.7 g of white solid, with a yield of 89%. 1 1H NMR (400 MHz, CDCl3) δ 7.97 (s, 1H), 7.92 (s, 1H), 7.80 (s, 6H), 7.70 (s, 4H), 7.56 (s, 4H), 7.44 (s, 3H), 7.38 (s, 3H), 7.29 (s, 1H), 6.90 (d, J = 15.4 Hz, 4H), 6.54 (s, 3H), 6.34 (d, J = 28.0 Hz, 8H), 1.47 (s, 6H), 1.32 (s, 24H), 0.96 (s, 12H).

[0039] Synthesis of Compounds SM6 and SM7

[0040] In a 100 mL two-necked flask, add the mixture SM4 and SM5 (1.7 g, 2.9 mmol), 2-bromonitrobenzene (0.9 g, 4.41 mmol), tetrakis(triphenylphosphine)palladium (0.2 g, 0.1 mmol), 15 mL of potassium carbonate solution (2 mol / L), and 48 mL of analytical grade toluene:ethanol (3:1). Under a nitrogen atmosphere, reflux at 80 °C for 24 hours. After the reaction is completed, cool to room temperature, rotary evaporate to remove the solvent, add water, extract with dichloromethane (3 × 50 mL), wash three times with water, dry over anhydrous magnesium sulfate, filter and collect the filtrate, and rotary evaporate the solvent. Using petroleum ether and dichloromethane (volume ratio 6:1) as the eluent, separate by column chromatography to obtain 1.5 g of a white solid with a yield of 89%. 1 H NMR (400 MHz, CDCl3) δ 8.31 (s, 1H), 8.23 (s, 1H), 8.13 (d, J = 6.4 Hz, 1H), 8.06 (d, J = 7.8 Hz, 1H), 7.86 (t, J = 7.6 Hz, 1H), 7.77 (t, J = 8.0 Hz, 3H), 7.67–7.58 (m, 2H), 7.55 (d, J = 6.8 Hz, 2H), 7.38 (q, J = 7.2 Hz, 1H), 7.31 (s, 2H), 7.23 (d, J = 10.8 Hz, 1H), 7.18 (t, J = 6.8 Hz, 1H), 6.95 (d, J = 20.8 Hz, 2H), 6.51 (d, J = 10.7 Hz, 5H), 6.41 (d, J = 10.6 Hz, 1H), 1.49 (s, 3H), 0.88 (s, 6H).

[0041] Synthesis of Compounds SM8 and SM9

[0042] In a 100 mL single-necked flask, add the mixture SM6 and SM7 (total 1.4 g, 2.4 mmol), triethyl phosphite (2.0 g, 12.0 mmol), and 25 mL of o-dichlorobenzene. Under a nitrogen atmosphere, reflux at 180 °C for 36 hours. After the reaction is completed, cool to room temperature, add water, extract with dichloromethane (3 × 50 mL), wash three times with water, dry over anhydrous magnesium sulfate, filter and collect the filtrate, and rotary evaporate the solvent. Using petroleum ether and dichloromethane (volume ratio 4:1) as the eluent, separate by column chromatography to obtain two white solids, namely SM8 0.6 g and SM9 0.1 g, with yields of 43% and 11% respectively. SM8: 11H NMR (400 MHz, CD2Cl2) δ 8.26 (s, 1H), 7.99 (s, 1H), 7.87 (d, J = 7.8 Hz, 1H), 7.81 (s, 2H), 7.68 (s, 2H), 7.53 (s, 1H), 7.50 (s, 2H), 7.39–7.28 (m, 4H), 7.19 (s, 1H), 7.08 (s, 1H), 6.88 (d, J = 6.4 Hz, 1H), 6.82 (s, 1H), 6.42 (s, 2H), 6.36–6.24 (m, 3H), 0.83 (s, 9H). SM9: 1 1H NMR (400 MHz, CD2Cl2) δ 8.26 (s, 1H), 7.98 (s, 1H), 7.84 (s, 1H), 7.80 (s, 2H), 7.69 (d, J = 8.4 Hz, 2H), 7.38 (t, J = 8.4 Hz, 3H), 7.31 (d, J = 7.5 Hz, 3H), 7.17 (s, 1H), 7.08 (s, 1H), 6.83 (s, 2H), 6.44 (s, 2H), 6.34 (d, J = 11.7 Hz, 4H), 1.40 (s, 9H).

[0043] Synthesis of Compound 1

[0044] Compound SM8 (0.4 g, 0.8 mmol), 2-chloro-4,6-diphenyl-1,3,5-triazine (0.3 g, 1.2 mmol), 60% sodium hydride (37.9 mg, 0.9 mmol) and 10 mL of N,N-dimethylformamide (DMF) were successively added to a 100 mL single-necked flask, and the mixture was refluxed at 150 °C for 24 hours. After the reaction was completed, it was cooled to room temperature, filtered by adding water, and dried under vacuum. Then, using petroleum ether and dichloromethane (volume ratio 10:1) as the eluent, 0.5 g of white solid was obtained by column chromatography separation, and the yield was 74%. 1 1H NMR (400 MHz, CDCl3) δ 9.75 (s, 1H), 9.18 (d, J = 8.3 Hz, 1H), 8.89 (d, J = 5.4 Hz, 4H), 8.11 (s, 1H), 7.96 (t, J = 8.4 Hz, 2H), 7.73 (t, J = 11.1 Hz, 7H), 7.59 (d, J = 7.3 Hz, 4H), 7.52–7.37 (m, 4H), 7.30 (d, J = 6.9 Hz, 1H), 7.00 (d, J = 6.4 Hz, 1H), 6.93 (s, 1H), 6.54 (s, 3H), 6.39 (s, 2H), 1.26 (s, 3H), 0.94 (s, 6H).

[0045] Synthesis of Compound 2

[0046] Its synthesis route and method are the same as those of Compound 1, except that Compound SM9 is used as the reactant. 1 HNMR(400MHz,CD2Cl2)δ8.04(s,1H),8.00(s,1H),7.94(d,J=7.7Hz,1H),7.69(d,J=8.5Hz,5H),7.54(d,J=7.1Hz,1H),7.38(t,J=8.0Hz,5H),7.32(d,J=7.0Hz,1H),7.18(dd,J=15.6,9.1Hz,5H),6.88(s,1H),6.85–6.80(m,3H),6.44–6.39(m,3H),6.33(d,J=7.6Hz,5H),1.40(s,9H).

[0047] Synthesis of Compound 3

[0048] Compound SM8 (0.2 g, 0.4 mmol), 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine (0.1 g, 0.4 mmol), 60% sodium hydride (17.4 mg, 0.4 mmol) and 10 mL of DMF were successively added to a 100 mL single-necked flask, and the mixture was refluxed at 150 °C for 24 hours. After the reaction was completed, it was cooled to room temperature, filtered by suction after adding water, and dried under vacuum. Using petroleum ether and dichloromethane (volume ratio 10:1) as the eluent, 230 mg of white solid was obtained by column chromatography separation, and the yield was 74%. 1 H NMR(400MHz,CDCl3)δ9.11(d,J=8.5Hz,2H),8.86(d,J=6.3Hz,4H),8.18(s,1H),8.01(s,1H),7.95(d,J=14.0Hz,3H),7.81(d,J=7.5Hz,1H),7.75(s,2H),7.68–7.53(m,11H),7.43(d,J=13.9Hz,2H),7.34(s,1H),7.23(s,1H),6.98(s,1H),6.92(s,1H),6.53(d,J=25.6Hz,3H),6.42–6.35(m,2H),0.96(s,9H).

[0049] Synthesis of Compound 4

[0050] Its synthesis route and method are the same as those of Compound 3, except that Compound SM9 is used as the reactant. 1HNMR (400 MHz, CDCl3) δ 9.11 (d, J = 8.5 Hz, 2H), 8.87 (d, J = 7.7 Hz, 4H), 8.19 (s, 1H), 8.01 (d, J = 7.7 Hz, 1H), 7.93 (d, J = 8.5 Hz, 3H), 7.79 (s, 1H), 7.74 (s, 2H), 7.64 (d, J = 7.4 Hz, 6H), 7.46 (dd, J = 24.2, 12.1 Hz, 6H), 7.33 (s, 1H), 7.23 (s, 1H), 6.95 (s, 2H), 6.57 (s, 2H), 6.53 (s, 2H), 6.45 (d, J = 8.1 Hz, 2H), 1.49 (s, 9H).

[0051] Synthesis of Compound 5

[0052] Into a 100 mL single-necked flask, add compound SM8 (0.2 g, 0.4 mmol), 2-(4-fluoro-3,5-dimethylphenyl)-4,6-diphenyl-1,3,5-triazine (0.2 g, 0.4 mmol), 60% sodium hydride (22 mg, 0.5 mmol) and 10 mL of DMF in sequence, and reflux at 150 °C for 24 hours. After the reaction is completed, cool to room temperature, add water and filter by suction. After vacuum drying, use petroleum ether and dichloromethane (volume ratio 10:1) as the eluent, and separate by column chromatography to obtain 89 mg of white solid, with a yield of 28%. 1 H NMR (400 MHz, CDCl3) δ 8.86 (d, J = 8.0 Hz, 4H), 8.73 (d, J = 7.2 Hz, 2H), 8.23 (s, 1H), 8.04 (d, J = 7.8 Hz, 1H), 7.73 (d, J = 20.3 Hz, 3H), 7.67–7.57 (m, 9H), 7.45 (s, 1H), 7.40–7.27 (m, 3H), 7.22 (d, J = 12.8 Hz, 2H), 6.97 (t, J = 12.4 Hz, 3H), 6.59 (s, 2H), 6.50 (s, 1H), 6.43 (d, J = 8.3 Hz, 1H), 6.36 (d, J = 8.7 Hz, 1H), 2.18 (s, 3H), 2.08 (s, 3H), 0.94 (s, 9H).

[0053] Synthesis of Compound 6

[0054] Its synthesis route and method are the same as those of Compound 5, with the difference that compound SM9 is used as the reactant. 1HNMR(400 MHz, CDCl3) δ 8.87 (s, 4H), 8.73 (s, 2H), 8.22 (s, 1H), 8.09 (s, 1H), 8.03 (s, 1H), 7.68 (dd, J = 30.9, 13.5 Hz, 9H), 7.52–7.44 (m, 3H), 7.33 (dd, J = 16.1, 8.4 Hz, 3H), 7.23 (d, J = 1.1 Hz, 1H), 7.00–6.94 (m, 3H), 6.57 (dt, J = 17.0, 8.6 Hz, 4H), 6.46 (d, J = 8.3 Hz, 2H), 2.14 (s, 6H), 1.50 (s, 9H).

[0055] Example 2

[0056] Compounds 1 - 6 in Example 1 were dissolved in toluene to form a 10 -5 M solution, and its ultraviolet-visible absorption was tested. It can be Figure 1 seen that the ultraviolet-visible absorption spectrum of the compound in solution generally has three absorption peaks: the absorption peak at short wavelength (280 nm) mainly belongs to the π-π* transition absorption of the molecule; the absorption peak at short wavelength (320 - 330 nm) mainly belongs to the n-π* transition absorption of the molecule; the absorption peak at long wavelength (345 - 370 nm) belongs to the charge transfer (ICT) transition absorption peak from the donor unit to the acceptor unit within the molecule. The absorption peaks of Compounds 1 and 2 are at 345 nm, the absorption peaks of Compounds 3 and 4 are at 367 nm, and the absorption peaks of Compounds 5 and 6 are at 365 nm.

[0057] Example 3

[0058] Compounds 1 - 6 in Example 1 were dissolved in toluene to form a 10 -5 M solution, and its photoluminescence spectrum was tested using an Edinburgh Transient / Steady-State Spectrometer FLS1000 (with a Xenon Lamp as the light source). Since the six molecules are pairwise isomers of each other, the emission peaks between the isomers almost overlap. It can be Figure 2 seen that the emission peaks of Compounds 1 and 2 are at 485 nm, the emission peaks of Compounds 3 and 4 are at 430 nm, and the emission peaks of Compounds 5 and 6 are at 425 nm. Under photoexcitation, all compounds are in the blue light region.

[0059] Example 4

[0060] Compounds 1 - 6 in Example 1 were doped into PMMA, and the photoluminescence spectrum of its 10 wt% PMMA doped film was tested. It can be Figure 3It can be seen that in the 10% PMMA-doped thin film, the emission peak of Compound 1 is 490 nm, the emission peak of Compound 2 is 470 nm, the emission peaks of Compounds 3 and 4 are both 442 nm, the emission peak of Compound 5 is 478 nm, and the emission peak of Compound 6 is 430 nm. Compared with the data measured in toluene solution, only Compound 2 shows an obvious blue shift, while the other five compounds show red shifts.

[0061] Example 5

[0062] Photoluminescence performance tests of Compounds 1-6 in Example 1 in different solutions. The six compounds were respectively dissolved in n-hexane, n-butyl ether, toluene, chloroform, tetrahydrofuran, ethyl acetate, and dichloromethane solutions, and their photoluminescence spectra in different solutions were measured, as Figures 4 to 9 shown. It can be seen from the figure that under photoexcitation, the emission wavelength of the compounds shows a certain red shift with the increase in solvent polarity, indicating that these compounds have strong intramolecular charge transfer.

[0063] Example 7

[0064] The transient lifetimes of Compounds 1-6 in Example 1 in toluene solution were measured under a nitrogen atmosphere, as Figure 10 shown. By fitting, the lifetimes of the six compounds were found to be 8.84, 12.82, 5.26, 4.97, 8.25, and 8.91 ns respectively, all of which are short lifetimes.

[0065] Example 8

[0066] Applications of Compound 3 and Compound 4 in Example 1 in organic light-emitting devices. Organic light-emitting diodes with structures of ITO / PEDOT:PSS (35 nm) / mCPCN:3:TAPC (1:2:7, 3:2:7, 4:2:7) / TmPyPB (45 nm) / LiF (0.5 nm) / Al (90 nm) and ITO / PEDOT:PSS (35 nm) / mCPCN:4:TAPC (4:2:7) / TmPyPB (45 nm) / LiF (0.5 nm) / Al (90 nm) were prepared using Compound 3 and 4 as the light-emitting layers of the devices. Among them, PEDOT:PSS is the hole injection layer, mCPCN:3:TAPC and mCPCN:4:TAPC are the light-emitting layer materials, TmPyPB is the electron transport layer, and LiF / Al is the cathode. The spin-coating process of the light-emitting layer is to dissolve Compound 3 or Compound 4 in chlorobenzene solution at a concentration of 10 mg / ml or 1 mg / ml, blend it with mCPCN and TAPC to form an exciplex, and then spin-coat it on the PEDOT:PSS injection layer at a rotation speed of 1700 r / min within 35 s to obtain a 55-nm-thick film. After the coating is completed, the substrate is annealed at a high temperature of 80 °C for 15 minutes to remove the residual solvent.

[0067] Compound 3 with a concentration of 10 mg / ml obtained the maximum external quantum efficiencies of 17.7%, 20.8% and 20.6% respectively in the devices with mass doping ratios of 1:2:7, 3:2:7 and 4:2:7, as Figure 11 shown; the maximum external quantum efficiencies of Compound 3 and 4 were 10.8% and 11.2% respectively in the device doped with 4:2:7 at the same concentration of 1 mg / ml, as Figure 12 shown.

[0068] Although the present invention has been described in conjunction with the preferred embodiments, the present invention is not limited to the above embodiments. It should be understood that the appended claims define the scope of the present invention. Under the guidance of the inventive concept of the present invention, those skilled in the art should be aware that certain changes made to the embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

Claims

1. A blue light material based on spirofluorene indole isomers, characterized in that, Using tert-butyl spirofluorene indole as the electron donor and triazine derivative as the electron acceptor; the molecular structural formula of the blue light material based on spirofluorene indole isomer is as follows:

2. Use of the blue light material based on spirofluorene indole isomers according to claim 1, characterized in that, Using the blue light material based on spirofluorene indole isomer as the luminescent layer dopant, an organic electroluminescent device is prepared by solution processing.

3. The application of the blue light material based on spirofluorene indole isomers according to claim 2, characterized in that, The preparation method of the luminescent layer is as follows: Dissolve the blue light material based on spirofluorene indole isomer in chlorobenzene solution, blend it with mCPCN and TAPC, and then spin-coat it on the surface of the hole injection layer. After annealing treatment, an organic electroluminescent diode luminescent layer is formed.

4. The application of the blue light material based on spirofluorene indole isomers according to claim 3, characterized in that, The concentration of the blue light material based on spirofluorene indole isomer in chlorobenzene solution is 1 - 10 mg / ml.

5. The application of the blue light material based on spirofluorene indole isomers according to claim 3, characterized in that, The mass doping ratio of the spirofluorene indole isomer-based blue light material, mCPCN, and TAPC is m mCPCN :m dopant :m TAPC = 1 - 4:2:

7.

6. The application of the blue-light material based on spirofluorene indole isomers according to claim 3, characterized in that, The spin-coating speed is 1500 - 1800 r / s.

7. Use of the blue light material based on spirofluorene indole isomers according to claim 3, characterized in that, The spin-coating thickness is 55 nm.

8. The application of the blue light material based on spirofluorene - indole isomers according to claim 3, wherein, The annealing temperature is 70 - 90 °C, and the annealing time is 15 min.

Images