A viscous flow state carbazole-indole-based narrow-band blue-violet light emitting material, a preparation method and applications thereof

Abstract

This invention provides a viscous flow-state carbazole-indole-based narrow-band blue-violet luminescent material, its preparation method, and its applications, belonging to the field of organic light-emitting materials. The viscous flow-state carbazole-indole-based blue-violet luminescent material prepared by this invention has a main blue-emitting framework obtained by connecting two phenyl groups at positions 2 and 10 of the carbazole-indole group, followed by flexible chain modification at positions 2 and 6 of the benzene group. Its core characteristic is that the molecule exhibits a viscous flow state and displays semiconductor properties. The luminescent material prepared by this invention has a regular molecular structure, good structural extensibility, good solubility, and excellent luminous efficiency, and can be used as a main luminescent material or a plasticized semiconductor molecule, thus showing great application prospects in the field of OLED displays.

Description

Technical Field

[0001] This invention belongs to the field of organic light-emitting materials, specifically relating to a viscous flow carbazole-indolyl narrow-band blue-violet light-emitting material, its preparation method, and its application. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are used in information displays, lighting, and medical diagnostic equipment. The controllable preparation of high-performance red, green, and blue primary color emitting materials is a prerequisite for realizing full-color OLED displays. Narrow-band OLEDs are currently the focus of research and development in achieving energy-saving, wide color gamut, and high-quality displays, and represent a direction for both academia and industry. Compared to red and green organic light-emitting molecules, wide-bandgap organic blue light-emitting materials have shorter wavelengths and higher energies, but typically suffer from a wider emission spectrum (over 40 nm), insufficient color purity, and poor stability, which are significant bottlenecks limiting their application in information displays. Especially in donor-acceptor fluorescent molecules and thermally activated delayed fluorescence, these molecules often exhibit strong electron-vibrational coupling and configurational relaxation in their conjugated systems, increasing vibrational degrees of freedom and enhancing charge-transfer excited-state characteristics, leading to a wider emission spectrum (typically 50-80 nm), thus limiting their application in high color gamut displays. Therefore, constructing a luminescent framework with molecular rigidity and local excited-state characteristics is an important strategy for improving color purity. Indole-carbazole luminescent frameworks, due to their fused-ring aromatic structure and highly planar π-conjugated system, have multi-dimensional and multifunctional sites. Introducing flexible or rigid modifying groups at different sites of carbazole can optimize the material structure, effectively restrict intramolecular configurational changes and vibrational degrees of freedom, thereby significantly suppressing excited-state structural relaxation and non-radiative decay processes. At the same time, the indole-carbazole unit has both a high triplet energy level and good electron donor characteristics, which is conducive to the luminescence behavior of local excited state and weak charge transfer characteristics, and can improve luminescence efficiency and conductivity, thereby obtaining a narrow-band emission spectrum with high color purity.

[0003] Although indolecarbazole-based luminescent frameworks can improve the color purity and luminous efficiency of materials, the rigid structure leads to poor solubility and molecular chain aggregation. Therefore, designing and preparing high-efficiency and high-color-purity indolecarbazole organic luminescent molecules is an important strategy for realizing the fabrication of flexible, high-performance narrow-band OLED devices. Summary of the Invention

[0004] The purpose of this invention is to provide a viscous flow carbazole-indole-based narrow-band blue-violet luminescent material, its preparation method, and its application. The prepared luminescent material exhibits semiconductor characteristics, has a regular structure, and possesses excellent and stable blue-violet luminescence properties.

[0005] In a first aspect, the present invention provides a viscous flow-state carbazole-indolyl narrow-band blue-violet light-emitting material, the general structural formula of which is as follows:

[0006]

[0007] In the formula: R1 is a branched alkyl chain with 6-16 carbon atoms.

[0008] In the viscous flow carbazole-indolyl narrow-band blue-violet luminescent material, R1 is a 16-branched alkyl chain with the following structural formula:

[0009]

[0010] Compound 1

[0011] Secondly, the present invention provides a method for preparing compound 1, as follows:

[0012] Step 1: and Potassium carbonate and tetraphenylphosphine palladium were added to a reaction flask, followed by a mixture of tetrahydrofuran / toluene. The mixture was then reacted at 85°C for 12 hours under a nitrogen atmosphere to obtain the compound. .

[0013] Step 2: Boron tribromide was added to a reaction flask, followed by dichloromethane, and the mixture was reacted at 0°C under a nitrogen atmosphere for 1 hour to obtain the compound. .

[0014] Step 3: , Potassium carbonate was added to a reaction flask, followed by N,N-dimethylformamide (DMF), and the mixture was reacted at 115°C for 12 hours under a nitrogen atmosphere to obtain the compound. .

[0015] Step 4: , Cesium carbonate was added to a reaction flask, followed by N,N-dimethylformamide (DMF), and the mixture was reacted at 135°C for 12 hours under a nitrogen atmosphere to obtain the compound. It was named 9,9'-(2,5-dibromo-1,4-phenylene)bis(3-(2,6-bis(2-hexyldecoxy)phenyl)-9H-carbazole).

[0016] Step 5: Add to the reaction flask The reaction mixture consisted of 9,9'-(2,5-dibromo-1,4-phenylene)bis(3-(2,6-bis(2-hexyldecoxy)phenyl)-9H-carbazole), benzyltriethylammonium chloride (TEBAC), triphenylphosphine, potassium carbonate, and palladium acetate. N,N-dimethylformamide (DMF) was added, and the reaction was carried out at 165°C under nitrogen protection for 24 hours. After the reaction was completed, water was added to quench the reaction, and the mixture was extracted with ethyl acetate. The ethyl acetate extracts of the organic phases were combined, dried over anhydrous sodium sulfate, and the desiccant and solvent were removed by filtration. The crude product was purified by silica gel column chromatography to finally obtain viscous flow compound 1.

[0017] Furthermore, the molar ratio of 9,9'-(2,5-dibromo-1,4-phenylene)bis(3-(2,6-bis(2-hexyldecoxy)phenyl)-9H-carbazole), benzyltriethylammonium chloride (TEBAC), triphenylphosphine, potassium carbonate, and palladium acetate is 0.6:1.2:1.68:5.95:0.06.

[0018] Thirdly, the present invention provides the application of a viscous flow state carbazole-indolyl narrow-band blue light emitting material to prepare an organic thin film layer for an organic electroluminescent device, wherein the organic electroluminescent device includes an anode, a cathode, and an organic thin film layer located between the anode and the cathode, and the organic thin film layer contains the viscous flow state fluorene-phenyl blue-violet light emitting material described in the first aspect.

[0019] Beneficial effects:

[0020] (1) The viscous flow carbazole-indolyl blue light emitting material of the present invention is prepared by a simple Szuki reaction, which has the advantages of simple preparation, mild reaction conditions, high yield and simple post-processing.

[0021] (2) The viscous flow carbazole-indolyl blue light emitting material prepared by the present invention has a regular structure, good structural extensibility and good solubility, and exhibits special flexible viscous flow physicochemical properties;

[0022] (3) The viscous flow carbazole-indolyl blue-violet luminescent material of the present invention has good luminous efficiency, and therefore has good application prospects in the field of blue OLED. The luminescent material can be used as a main luminescent material and a plasticized organic semiconductor material. Attached Figure Description

[0023] Figure 1 The pICz-D2Hd proton NMR spectrum;

[0024] Figure 2 The UV-absorbing and visible-emitting spectra of pICz-D2Hd toluene solution and thin film are shown.

[0025] Figure 3A fluorescence image of pICz-D2Hd in the viscous flow state;

[0026] Figure 4 The DSC spectrum of pICz-D2Hd;

[0027] Figure 5 The TGA spectrum of pICz-D2H;

[0028] Figure 6 The CV spectrum of pICz-D2H;

[0029] Figure 7 The electroluminescence spectrum of pICz-D2H is shown.

[0030] Figure 8 This is a graph showing the current density, luminous intensity, and voltage of a pICz-D2H-based light-emitting diode device. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0032] Carbazole-indolyl blue light molecules exhibit complex electronic transition sequences, vibrational relaxation, conformational transitions, and aggregation behaviors, resulting in broad-band, multi-peak, long-baseline, and long-wavelength emission, which reduces the color purity and stability of blue light. By employing steric hindrance and molecular encapsulation strategies to suppress π-electron coupling between conjugated backbones, excited-state behavior of a single molecular state can be achieved, thereby improving color purity and efficiency.

[0033] The carbazole-indole group itself has a λ at 400 nm PL The viscous flow luminescent molecules, through chemical modification, can easily achieve efficient blue light emission. Compared to solid-state blue light-emitting materials, these molecules possess intrinsic flexibility and exhibit excellent and stable blue light emission characteristics, showing broad application prospects in the field of flexible OLED display technology. The multi-site functionalization of the carbazole-indole molecular unit itself provides an effective molecular design strategy for constructing viscous flow luminescent molecules.

[0034] The present invention relates to a type of viscous flow carbazole-indolyl blue light-emitting material, the main blue light-emitting framework of which is obtained by connecting two phenyl groups at the 2 and 10 positions of the carbazole-indolyl group, and then by modifying the 2 and 6 positions of benzene with flexible chains. Its core feature is that the molecule exhibits a viscous flow state and displays semiconductor properties.

[0035] Example 1: Synthesis of Compound 1

[0036] The synthesis method is as follows:

[0037] first step:

[0038]

[0039] Product 1

[0040] 3-Bromocarbazole (1 g, 4.0 mmol), 2,6-methoxyphenylboronic acid (0.9 g, 4.8 mmol), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4, 0.3 g, 0.2 mmol), and potassium carbonate (K2CO3, 3.3 g, 24 mmol) were added to a reaction flask. 30 mL of deoxygenated toluene / tetrahydrofuran (Tol / THF, 1:1 v / v) and 12 mL of deoxygenated water were added to the flask, and the reaction temperature was maintained at 85 °C. The reaction was carried out under nitrogen protection for 12 hours until the substrate was completely reacted. After the reaction was complete, water was added to quench the reaction, and the product was extracted with dichloromethane, dried over anhydrous sodium sulfate, filtered to remove the desiccant and solvent, and purified by silica gel column chromatography to obtain solid product 1.

[0041] Step Two:

[0042]

[0043] Product 1 Product 2

[0044] Add product 1 (1.0 g, 3.3 mmol) to the reaction flask, then add 5 mL of dry dichloromethane (DCM) to the flask. Add boron tribromide (BBr3 (2 M), 8 mL, 16.5 mmol) to the reaction flask under an ice-water bath. O The reaction was carried out at C for 1 hour until the substrate was completely reacted. After the reaction was completed, water was added to quench the reaction. The product was extracted with dichloromethane, dried with anhydrous sodium sulfate, filtered to remove the desiccant and solvent, and the crude product was purified by silica gel chromatography to obtain solid product 1.

[0045] Step 3:

[0046]

[0047] Product 2 Product 3

[0048] Product 2 (1.0 g, 3.6 mmol), 1-bromo-2-hexyldecane (2.7 g, 9 mmol), and potassium carbonate (K₂CO₃, 3.0 g, 21.6 mmol) were added to a reaction flask. 10 mL of N,N-dimethylformamide (DMF) was then added to the flask, and the reaction temperature was maintained at 115 °C. The reaction was carried out under nitrogen protection for 12 hours until the substrates were completely reacted. After the reaction was complete, water was added to quench the reaction, and the mixture was extracted with ethyl acetate. The combined ethyl acetate extracts of the organic phases were dried over anhydrous sodium sulfate, the drying agent was removed, and the solvent was eliminated. The crude product was purified by silica gel column chromatography to obtain viscous product 3.

[0049] Step 4:

[0050]

[0051] Product 3 Product 4

[0052] Product 3 (1 g, 1.4 mmol), 1,4-dibromo-2,5-difluorobenzene (0.2 g, 0.7 mmol), and cesium carbonate (Cs₂CO₃, 0.5 g, 1.6 mmol) were added to a reaction flask. 10 mL of N,N-dimethylformamide (DMF) was then added to the flask, and the reaction temperature was maintained at 135 °C. The reaction was carried out under nitrogen protection for 12 hours until the substrates were completely reacted. After the reaction was complete, water was added to quench the reaction, and the mixture was extracted with ethyl acetate. The combined ethyl acetate extracts of the organic phases were dried over anhydrous sodium sulfate, the drying agent was removed, and the solvent was eliminated. The crude product was purified by silica gel column chromatography to obtain viscous product 4.

[0053] Step 5:

[0054]

[0055] Product 4: Compound 1 (pICz-D2Hd)

[0056] Add 9,9'-(2,5-dibromo-1,4-phenylene)bis(3-(2,6-bis(2-hexyldecoxy)phenyl)-9H-carbazole (1 g, 0.6 mmol), benzyltriethylammonium chloride (TEBAC, 0.27 g, 1.2 mmol), triphenylphosphine (PPh3, 0.44 g, 1.68 mmol), potassium carbonate (K2CO3, 0.82 g, 5.95 mmol), and palladium acetate (Pd(OAc)2, 0.01 g, 0.06 mmol) to the reaction flask. Add 10 mL of N,N-dimethylacetamide (DMAC) to the reaction flask and maintain the reaction temperature at 165 °C. The reaction was carried out under nitrogen protection for 24 hours until the substrate was completely reacted. After the reaction was completed, water was added to quench the reaction, and the mixture was extracted with ethyl acetate. The ethyl acetate extracts of the organic phases were combined, dried with anhydrous sodium sulfate, the desiccant was filtered off, the solvent was removed, and the crude product was purified by silica gel column chromatography to obtain viscous flow pICz-D2Hd.

[0057] like Figure 1 The figure shows the 1H NMR spectrum of pICz-D2Hd prepared in Example 1 of this invention. 1H NMR (400MHz, Chloroform-d) δ 7.99 (s, 2H), 7.85 (d, J = 7.6 Hz, 2H), 7.58 (d, J = 8.5Hz, 2H), 7.41 (d, J = 8.4 Hz, 2H), 7.24 (d, J = 8.2 Hz, 2H), 7.10 (d, J = 6.3Hz, 2H), 7.01 (s, 2H), 6.66 – 6.44 (m, 6H), 3.67 (d, J = 5.4 Hz, 8H).

[0058] Material property testing:

[0059] 1. Spectral testing

[0060] Absorption and emission spectroscopic properties of pICz-D2Hd: The pICz-D2Hd prepared in Example 1 was dissolved in toluene solution to obtain a toluene solution with a concentration of 5 mg / mL. The resulting solution was denoted as pICz-D2Hd-S, where S represents being in solution. The pICz-D2Hd-S solution was spin-coated on a spin coater at a rotation speed of 1500 rmp / min to obtain the corresponding film, denoted as pICz-D2Hd-F, where F represents being in film. Figure 2 The UV-absorbing and visible-emitting spectra of pICz-D2Hd toluene solution and thin film are shown below. Figure 2It can be seen that the absorption and emission wavelengths of the pICz-D2Hd-S solution are approximately 290 nm and 340 nm, respectively, while the maximum absorption and emission wavelengths of the pICz-D2Hd-F film are approximately 285 nm and 434 nm, respectively, exhibiting good blue light emission.

[0061] 2. Viscous Flow Properties

[0062] Figure 3 This is a fluorescence image of the pICz-D2Hd material in its viscous flow state according to Example 1 of this invention. As can be seen from the image, the pICz-D2Hd material exhibits excellent viscous flow physical behavior when picked up with a glass rod.

[0063] 3. Thermal stability test

[0064] The glass transition temperature T of pICz-D2Hd g and thermal weight loss temperature T d The test results are as follows Figure 4 and Figure 5 As shown. It can be seen that, Figure 4 The image shows the DSC spectrum of pICz-D2Hd. The DSC test shows that the glass transition temperature Tg of pICz-D2Hd is less than 0℃, which proves that the pICz-D2Hd material has viscous flow physical properties at room temperature.

[0065] Figure 5 The TGA spectrum of pICz-D2Hd shows the thermogravimetric temperature T of pICz-D2Hd. d The temperature was 382.6℃. This data shows that the pICz-D2Hd prepared by this invention has excellent thermal stability, which can meet the requirements for the use of organic electroluminescent materials.

[0066] 4. Energy level structure testing

[0067] Figure 6 The image shows the CV spectrum of pICz-D2Hd. Based on the CV measurements of the two materials, the corresponding HOMO and LUMO energy level values ​​can be obtained. The HOMO and LUMO energy levels of pICz-D2Hd are -5.55 eV and -2.59 eV, respectively. The band gap value of pICz-D2Hd (E...) is... g The values ​​are 2.96 eV and the band gap is less than 3 eV, indicating that the material emits blue light.

[0068] Example 2: Fabrication of Organic Electroluminescent Devices

[0069] The ITO substrate was ultrasonically cleaned sequentially with detergent, acetone, isopropanol, and deionized water, dried in an oven at 120°C for 2 hours, and treated with ultraviolet ozone for 10 minutes before spin coating. First, a 40 nm thick PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) was prepared at a spin speed of 1500 rpm and annealed at 120°C for 30 minutes. The HOMO and LUMO levels of PVK (poly(9-vinylcarbazole)) were -5.8 eV and -2.0 eV, respectively. The energy levels of PVK and pICz-D2Hd exhibited a stepwise matching. To facilitate electron and hole transport, 20 wt% of the viscous flow luminescent material pICz-D2Hd prepared in Example 1 was co-doped with PVK in a 20 mg / mL toluene solution and spin-coated at 1500 rpm, annealed at 120°C for 20 minutes in a nitrogen atmosphere. The thickness of the spin-coated film of the viscous luminescent material is approximately 50 nm. Finally, at a thickness of less than 1 × 10⁻⁶ nm... −5 Organic electroluminescent devices with an area of ​​1.5 mm × 1.5 mm were prepared by thermal evaporation under a pressure of mbar, consisting of 25 nm TPBi, 0.8 nm LiF, and 100 nm Al.

[0070] Example 3: Device Testing

[0071] The characteristics of the organic electroluminescent device prepared in Example 2 were measured, and all device parameters were measured in an air environment.

[0072] Figure 7 Electroluminescence spectra of the blend of PVK and pICz-D2Hd; Figure 8 The figure shows the voltage-brightness versus current density curves of the OLED device fabricated from pICz-D2Hd. As can be seen from the figure, the viscous flow carbazole-indolyl blue light-emitting material of this invention, when applied to organic electroluminescent devices, can achieve good blue light emission intensity.

[0073] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention.

Claims

1. A viscous flow carbazole-indolyl narrow-band blue-violet luminescent material, characterized in that, The general structural formula of the viscous flow carbazole-indolyl narrow-band blue-violet light-emitting material is as follows: ； In the formula: R1 is a branched alkyl chain with 6-16 carbon atoms.

2. The viscous flow carbazole-indolyl narrow-band blue-violet light-emitting material according to claim 1, characterized in that, R1 is a branched alkyl chain with 16 carbon atoms. The structural formula of the viscous flow carbazole-indolyl narrow-band blue-violet luminescent material is as follows: 。 3. The method for preparing the viscous flow carbazole-indolyl narrow-band blue-violet light-emitting material according to claim 2, characterized in that, The preparation method is as follows: 9,9'-(2,5-dibromo-1,4-phenylene)bis(3-(2,6-bis(2-hexyldecoxy)phenyl)-9H-carbazole), benzyltriethylammonium chloride, triphenylphosphine, potassium carbonate, and palladium acetate were added to a reaction flask. N,N-dimethylacetamide was then added, and the reaction temperature was maintained at 165°C. The reaction was carried out for 24 hours under nitrogen protection to obtain the viscous flow carbazole-indolyl narrow-band blue-violet luminescent material.

4. The preparation method according to claim 3, characterized in that, The molar ratio of 9,9'-(2,5-dibromo-1,4-phenylene)bis(3-(2,6-bis(2-hexyldecoxy)phenyl)-9H-carbazole), benzyltriethylammonium chloride, triphenylphosphine, potassium carbonate, and palladium acetate is 0.6:1.2:1.68:5.95:0.

06.

5. The application of the viscous flow carbazole-indolyl narrow-band blue-violet light-emitting material according to claim 1 in the preparation of organic electroluminescent devices, characterized in that it is used to, Organic thin film layers used to prepare organic electroluminescent devices.

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