Multi-resonance organic small molecular luminescent material and application thereof in organic light-emitting diode

Abstract

The invention provides a multi-resonance small-molecular luminescent material and an organic electroluminescent diode, and relates to the technical field of organic luminescent materials, the chemical structural general formula of the multi-resonance small-molecular luminescent material is as shown in formula (I), and R represents hydrogen, tert-butyl or a benzene ring. The multi-resonance micromolecular luminescent material is low in synthesis difficulty, high in yield, narrow in fluorescence spectrum and good in efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of organic light-emitting materials, and in particular to a multi-resonance small molecule light-emitting material and an organic electroluminescent diode. Background Art

[0002] In recent decades, organic light-emitting diode (OLED) technology has made great progress and has become the most promising full-color display and lighting technology. Organic light-emitting diode (OLED) has the characteristics of fast response speed, wide viewing angle, light and thin, low energy consumption, and easy flexibility because it does not rely on backlight to actively emit light. Therefore, OLED has attractive application prospects and a broad application market in solid-state lighting and flat panel display. Especially in the field of flat panel display, as users have higher and higher requirements for products, high-definition displays as the mainstream of OLED displays have put forward more stringent requirements on the luminescence performance of OLED luminescent materials. Among them, in addition to the efficiency and stability of luminescent materials, the most important indicator is the narrow emission half-peak width. Traditional fluorescent materials and general TADF materials have relatively wide half-peak widths. If narrow-band luminescence is achieved, a filter system must be added to the two materials with wider emission half-peak widths to cut off the excess emission bands. However, the above operation will significantly reduce the performance of the material and increase the manufacturing cost of the device.

[0003] Organic light-emitting diodes (OLEDs) are a successful light-emitting device that can realize efficient electroluminescent (EL) devices through engineering luminescent materials. They can cover all visible colors, and red, green and blue OLEDs are being used in commercial products. Even near-infrared OLEDs have been studied and are being actively developed. The use of chemical modification methods to prepare multi-resonance materials with narrow emission peak widths provides a more convenient and efficient way. Multi-resonance materials are organic molecules in which atoms or groups with opposite electronegativity are embedded in polycyclic aromatic hydrocarbons. Due to the opposite multi-resonance effect, the frontier molecular orbitals (FMOs) are compensated by the same atoms or groups. This type of material has the advantages of narrow-band luminescence, strong thermal stability, good charge transfer performance and high efficiency. The multi-resonance materials that have been proposed are mostly based on BN(O) multi-resonance small molecules and carbonyl-N multi-resonance small molecules. There are problems such as high synthesis difficulty and low yield, or wide fluorescence spectrum and poor efficiency. Summary of the invention

[0004] The technical problem solved by the present invention is to address at least one of the following aspects: high difficulty in synthesizing multi-resonance materials, low yield, wide fluorescence spectrum and poor efficiency.

[0005] In order to solve the above problems, the present invention provides a multi-resonance small molecule luminescent material, the chemical structure of the multi-resonance small molecule luminescent material is shown in formula (I):

[0006]

[0007] Among them, R 1 -R 4 Each is independently one of hydrogen, an alkyl group having 1 to 10 carbon atoms, a cyano group, an aryl group or a heteroaryl group having 5 to 25 carbon atoms and containing at least one substituent or unsubstituted;

[0008] The substituents are selected from alkyl groups having 1 to 10 carbon atoms.

[0009] Some specific multi-resonance small molecule luminescent materials, R 1 -R 4 Each is independently one of hydrogen, an alkyl group having 1 to 10 carbon atoms, a cyano group, a C5-C15 phenyl group having at least one substituent or no substituent, or a heteroaryl group.

[0010] The substituents are selected from alkyl groups having 1 to 10 carbon atoms.

[0011] The heteroatom on the heteroaryl group is selected from at least one of O, N, and S.

[0012] Some specific multi-resonance small molecule luminescent materials, R 1 -R 4 Each is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or a C5-C15 aryl group having at least one substituent or having no substituent.

[0013] The substituent is selected from an alkyl group having 1 to 6 carbon atoms.

[0014] Some specific multi-resonance small molecule luminescent materials, R 1 -R 4 Each is independently hydrogen, an alkyl group having 1 to 5 carbon atoms, or a phenyl group having at least one substituent or no substituent.

[0015] The substituent is selected from an alkyl group having 1 to 5 carbon atoms.

[0016] Some specific multi-resonance small molecule luminescent materials, R 1 -R 4 Each is independently hydrogen, tert-butyl or phenyl which may have at least one substituent or may not have a substituent.

[0017] The substituent is tert-butyl.

[0018] Furthermore, the multi-resonance small molecule luminescent material is selected from the following structures:

[0019]

[0020] Furthermore, the steady-state fluorescence spectrum of the multi-resonance small molecule luminescent material in toluene solution is in the range of 380-800 nm, and the half-peak width is less than or equal to 40 nm.

[0021] The present invention also provides an organic electroluminescent diode, wherein the light-emitting layer of the diode comprises at least one of the above-mentioned multi-resonance small molecule light-emitting materials.

[0022] Some specific technical solutions, the organic electroluminescent diode includes an anode layer, a hole injection layer, at least one hole transport layer, a light-emitting layer, at least one electron transport layer, an electron injection layer and a cathode layer stacked in sequence, and the light-emitting layer includes the multi-resonance small molecule light-emitting material described above.

[0023] Furthermore, the mass percentage of the multi-resonance small molecule luminescent material in the luminescent layer is 0.1%-20%.

[0024] Furthermore, in the light-emitting layer, the mass percentage of the multi-resonance small molecule light-emitting material is 0.1%-15%.

[0025] Furthermore, in the light-emitting layer, the mass percentage of the multi-resonance small molecule light-emitting material is 3%-12%.

[0026] Furthermore, the thickness of the light-emitting layer is 10nm-200nm.

[0027] The advantages of the organic light-emitting diode described in the present invention over the prior art are the same as the advantages of the multi-resonance small molecule light-emitting material over the prior art, which will not be repeated here.

[0028] The organic small molecule luminescent material of the present invention has the following characteristics:

[0029] 1. The molecular system is novel, has a large expansion space and a narrow half-peak width of the spectrum.

[0030] 2. The multi-resonance small molecule luminescent material of the present invention is easy to synthesize, and the raw materials are cheap and easily available. At the same time, it has a rigid skeleton structure and a planar structure, which reduces the vibration relaxation during the radiation transition process, and gives the molecule good thermal stability and the luminescent film good charge transfer performance, which is beneficial to improving the efficiency and stability of the device.

[0031] 3. The matrix of the organic small molecule luminescent material of the present invention is a CN multi-resonance structure based on carbazole. Compared with the DA or D-π-A structure of the thermally activated delayed fluorescence (TADF) material, it can well separate the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), greatly reducing the excited state configuration transition. The whole molecule therefore exhibits narrow-band luminescence. At the same time, compared with the BN multi-resonance structure that must rely on extremely dangerous alkyl lithium reagents and low-yield introduction of B atoms, the present invention only needs to construct a multi-resonance skeleton through aromatic nucleophilic substitution and intramolecular Heck coupling or dehydrogenation coupling, which is safer, more convenient and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 2 is the thermogravimetric curve of pDCz-BP and pSCz-BP in Examples 1-2 of the present invention.

[0033] Figure 2 The UV-visible absorption spectra of the compound pDCz-BP in Example 1 of the present invention in n-hexane, toluene, chloroform, tetrahydrofuran, acetonitrile and methanol solutions are shown in FIG.

[0034] Figure 3 The UV-visible absorption spectra of the compound pSCz-BP in Example 2 of the present invention in n-hexane, toluene, dichloromethane, tetrahydrofuran, acetonitrile and methanol solutions are shown in FIG.

[0035] Figure 4 The photoluminescence spectra of the compound pDCz-BP in Example 1 of the present invention in n-hexane, toluene, chloroform, tetrahydrofuran, acetonitrile and methanol solutions are shown in FIG.

[0036] Figure 5 The photoluminescence spectra of the compound pSCz-BP in Example 2 of the present invention in n-hexane, toluene, dichloromethane, tetrahydrofuran, acetonitrile and methanol solutions are shown in FIG.

[0037] Figure 6 1 is the structure and energy level diagram of the organic light emitting diode device according to Example 11 of the present invention.

[0038] Figure 7 1 is the structure and energy level diagram of the organic light emitting diode device according to Example 12 of the present invention.

[0039] Figure 8 This is a current density-voltage-brightness curve of the organic light emitting diode of Example 11 of the present invention.

[0040] Fig. 9 This is a current density-voltage-brightness curve of the organic light emitting diode of Example 12 of the present invention.

[0041] Fig.10The brightness-external quantum efficiency curves of the organic light emitting diodes of Examples 11 and 12 of the present invention are shown.

[0042] Fig.11 The electroluminescence spectra of the organic electroluminescent diodes of Examples 11 and 12 of the present invention are shown.

[0043] Fig.12 It is the general structural formula of the multi-resonance small molecule luminescent material of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0045]

[0046] Example 1: Multi-resonance small molecule luminescent material compound

[0047] The synthesis steps of pDCz-BP are as follows:

[0048] Step 1: Add the raw material 1-1 (5.17 g, 16.18 mmol), 1,4-dibromo-2,3-difluorobenzene (2 g, 7.36 mmol), and cesium carbonate (10.55 g, 32.37 mmol) to a 250 ml three-necked flask, then add 40 ml of N, N-dimethylformamide (DMF), evacuate and replace nitrogen three times, and then stir and react for 12 hours at 75 ° C in a nitrogen atmosphere. After cooling, add a large amount of water, precipitate the product, and then filter it, recrystallize it with dichloromethane and methanol to obtain 3.81 g of a white powdery crude product of 2-1, with a yield of 73%.

[0049] Step 2: Add the dried compound 2-1 (3.0 g, 3.45 mmol), palladium acetate (0.26 g, 1.17 mmol), triphenylphosphine (2.62 g, 9.99 mmol), potassium carbonate (4.76 g, 34.46 mmol), benzyltriethylammonium chloride (1.57 g, 6.89 mmol) to a 250 ml three-necked flask, add 50 ml of dimethylacetamide (DMAc), evacuate and replace nitrogen three times, and then stir and react under reflux conditions in a nitrogen atmosphere for 12 hours. After cooling, add a large amount of water to precipitate a dark green solid, then wash with a large amount of ethanol, and then use column chromatography to separate and purify, and then dry to obtain a light yellow powder pDCz-BP, which weighs 1.67 g and has a yield of 68.5%. After recrystallization, a light yellow powder pDCz-BP pure product 1.06 g is obtained, and the yield is 63.5%.

[0050] The nuclear magnetic resonance spectrum of the compound pDCz-BP is: 1H MMR (400 MHz, Chloroform-d) δ8.39 (d, 3H), 8.33 (s, 1H), 8.29 (s, 1H), 8.22 (s, 1H), 8.09 (d, 1H), 7.95 (d, 1H), 7.80 (d, 1H), 7.74-7.62 (m, 11H), 7.50-7.39 (m, 10H), 7.34-7.25 (m, 4H). 13C NMR (400 MHz, Chloroform-d) δ145.87, 144.25, 142.44, 139.25, 139.09, 136.82, 132.56, 131.9 0,130.22,130.17,130.12,129.71128.77,128.38,128.05,127.91,127.57,127.08,125.26,123.11,121.20,120.90,120.26,120.02,119.41,114.42,113.77,MALDI-TOF: found by 710.2717.

[0051] Example 2: The synthesis steps of the multi-resonance small molecule luminescent material compound pSCz-BP are as follows:

[0052] Step 1: Add the raw material 1-2 (4.52 g, 16.18 mmol), 1,4-dibromo-2,3-difluorobenzene (2 g, 7.36 mmol), and cesium carbonate (10.55 g, 32.37 mmol) to a 250 ml three-necked flask, then add 40 ml of N, N-dimethylformamide (DMF), evacuate and replace nitrogen three times, and then stir and react for 12 hours at 75 ° C in a nitrogen atmosphere. After cooling, add a large amount of water, precipitate the product, filter it, and recrystallize it with dichloromethane and methanol to obtain 4.55 g of a white powdery crude product of 2-2 with a yield of 78.3%.

[0053] Step 2: Add the dried compound 2-2 (3.0 g, 3.79 mmol), palladium acetate (0.29 g, 1.29 mmol), triphenylphosphine (2.89 g, 11.00 mmol), potassium carbonate (5.24 g, 37.94 mmol), benzyltriethylammonium chloride (1.73 g, 7.59 mmol) to a 250 ml three-necked flask, add 50 ml of dimethylacetamide (DMAc), evacuate and replace nitrogen three times, and then stir and react under reflux conditions in a nitrogen atmosphere for 12 hours. After cooling, add a large amount of water to precipitate a dark green solid, then wash with a large amount of ethanol, and then use column chromatography to separate and purify, and then dry to obtain a light yellow powder pSCz-BP, which weighs 1.52 g and has a yield of 63.5%. After recrystallization, a light yellow powder pSCz-BP pure product 0.93 was obtained, and the yield was 61.5%.

[0054] The NMR spectrum of the compound pSCz-BP is: 1H MMR (400MHz, Chloroform-d) δ8.22 (s, 1H), 8.17 (s, 2H), 8.12 (s, 2H), 8.07 (s, 1H), 8.02 (d, 1H), 7.84 (d, 1H), 7.64-7.57 (m, 2H), 7.43 (d, 2H), 7.34 (s, 2H), 1.48 (s, 9H), 1.42 (d, 27). 13C NMR (151 MHz, Chloroform-d) δ 147.31, 145.39, 143.85, 142.89, 140.13, 137.88, 137.20, 131.78, 131.45, 130.24, 125.48, 124.46, 123.78, 123.27, 121.85, 120.02, 118.58, 117.62, 117.44, 117.05, 116.39, 112.92, 111.74, 109.33, 366.02, 34.97, 34.78, 32.64, 31.92, 31.76, MALDI-TOF: found by 630.3937.

[0055] Example 3: The synthesis steps of multi-resonance small molecule luminescent material compound 3-3a are as follows:

[0056] Step 1: Add the raw material 3-1 (6.15 g, 16.18 mmol), 1,4-dibromo-2,3-difluorobenzene (2 g, 7.36 mmol), cesium carbonate (10.55 g, 32.37 mmol) to a 250 ml three-necked flask, then add 40 ml N, N-dimethylformamide (DMF), evacuate and replace nitrogen three times, and then stir and react for 12 hours at 75 ° C in a nitrogen atmosphere. After cooling, add a large amount of water, precipitate the product, filter it, and recrystallize it with dichloromethane and methanol to obtain 5.50 g of a white powdery crude product of 3-2 with a yield of 75.5%.

[0057] Step 2: Add the dried compound 3-2 (3.0 g, 3.03 mmol), palladium acetate (0.23 g, 1.13 mmol), triphenylphosphine (2.30 g, 8.78 mmol), potassium carbonate (4.18 g, 30.28 mmol), benzyltriethylammonium chloride (1.38 g, 6.06 mmol) to a 250 ml three-necked flask, add 50 ml of dimethylacetamide (DMAc), evacuate and replace nitrogen three times, and then stir and react under reflux conditions in a nitrogen atmosphere for 12 hours. After cooling, add a large amount of water to precipitate a dark green solid, then wash with a large amount of ethanol, and then use column chromatography to separate and purify, and then dry to obtain a light yellow powder 3-3a, which weighs 1.55 g and has a yield of 61.8%.

[0058] Example 4: The synthesis steps of multi-resonance small molecule luminescent material compound 4-3b are as follows:

[0059] Step 1: Add the raw material 4-1 (6.66g, 16.18mmol), 1,4-dibromo-2,3-difluorobenzene (2g, 7.36mmol), cesium carbonate (10.55g, 32.37mmol) to a 250ml three-necked flask, then add 40ml N,N-dimethylformamide (DMF), evacuate and replace nitrogen three times, and then stir and react for 12h at 75°C in a nitrogen atmosphere. After cooling, add a large amount of water, precipitate the product, filter it, and recrystallize it with dichloromethane and methanol to obtain 4.81g of a white powdery crude product of 4-2, with a yield of 62.0%.

[0060] Step 2: Add the dried compound 4-2 (3.0 g, 2.84 mmol), palladium acetate (0.22 g, 0.97 mmol), triphenylphosphine (2.16 g, 8.25 mmol), potassium carbonate (3.93 g, 28.44 mmol), benzyltriethylammonium chloride (1.29 g, 5.69 mmol) to a 250 ml three-necked flask, add 50 ml of dimethylacetamide (DMAc), evacuate and replace nitrogen three times, and then stir and react under reflux conditions in a nitrogen atmosphere for 12 hours. After cooling, add a large amount of water to precipitate a dark green solid, then wash with a large amount of ethanol, and then use column chromatography to separate and purify, and then dry to obtain a light yellow powder 4-3b, which weighs 1.50 g and has a yield of 58.8%.

[0061] Example 5: The synthesis steps of multi-resonance small molecule luminescent material compound 5-3c are as follows:

[0062] Step 1: Add the raw material 5-1 (5.20 g, 16.18 mmol), 1,4-dibromo-2,3-difluorobenzene (2 g, 7.36 mmol), cesium carbonate (10.55 g, 32.37 mmol) to a 250 ml three-necked flask, then add 40 ml N, N-dimethylformamide (DMF), evacuate and replace nitrogen three times, and then stir and react for 12 hours at 75 ° C in a nitrogen atmosphere. After cooling, add a large amount of water, precipitate the product, filter it, and recrystallize it with dichloromethane and methanol to obtain 5.08 g of a white powdery crude product of 5-2, with a yield of 79.0%.

[0063] Step 2: Add the dried compound 5-2 (3.0 g, 3.43 mmol), palladium acetate (0.22 g, 0.97 mmol), triphenylphosphine (2.61 g, 9.95 mmol), potassium carbonate (4.74 g, 34.30 mmol), benzyltriethylammonium chloride (1.56 g, 6.86 mmol) to a 250 ml three-necked flask, add 50 ml of dimethylacetamide (DMAc), evacuate and replace nitrogen three times, and then stir and react under reflux conditions in a nitrogen atmosphere for 12 hours. After cooling, add a large amount of water to precipitate a dark green solid, then wash with a large amount of ethanol, and then use column chromatography to separate and purify, and then dry to obtain a light yellow powder 5-3c, which weighs 1.22 g and has a yield of 49.7%.

[0064] Example 6: The synthesis steps of multi-resonance small molecule luminescent material compound 6-3d are as follows:

[0065] Step 1: Add the raw material 6-1 (8.05g, 16.18mmol), 1,4-dibromo-2,3-difluorobenzene (2g, 7.36mmol), cesium carbonate (10.55g, 32.37mmol) to a 250ml three-necked flask, then add 40ml N,N-dimethylformamide (DMF), evacuate and replace nitrogen three times, then stir and react for 12h at 75°C in a nitrogen atmosphere. After cooling, add a large amount of water, precipitate the product, filter it, and recrystallize it with dichloromethane and methanol to obtain 5.22g of a white powdery crude product of 6-2, with a yield of 57.8%.

[0066] Step 2: Add the dried compound 6-2 (3.0 g, 2.44 mmol), palladium acetate (0.19 g, 0.83 mmol), triphenylphosphine (1.86 g, 7.09 mmol), potassium carbonate (3.38 g, 24.45 mmol), benzyltriethylammonium chloride (1.11 g, 4.89 mmol) to a 250 ml three-necked flask, add 50 ml of dimethylacetamide (DMAc), evacuate and replace nitrogen three times, and then stir and react under reflux conditions in a nitrogen atmosphere for 12 hours. After cooling, add a large amount of water to precipitate a dark green solid, then wash with a large amount of ethanol, and then use column chromatography to separate and purify, and then dry to obtain a light yellow powder 6-3d, which weighs 1.72 g and has a yield of 65.8%.

[0067] Step 3: Compounds pDCz-BP and pSCz-BP in Examples 1 and 2 were heated in a N 2 The temperature was raised at a rate of 10°C / min under protection, and the thermal gravimetric curve was measured using a differential scanning calorimeter model DSC 204. Figure 1 It can be seen that the temperature at which the compound pDCz-BP decomposes by 5% is 516°C, and the temperature at which the compound pSCz-BP decomposes by 5% is 384°C, indicating that the two materials have good thermal stability.

[0068] Example 7: UV-visible light absorption performance test of the compound pDCz-BP in Example 1 in different solutions. The compound pDCz-BP was dissolved in n-hexane, toluene, dichloromethane, tetrahydrofuran, acetonitrile and methanol solutions (all with a concentration of 10 -5 M), and use UV-visible absorption spectrometer to test its UV-visible light absorption performance in different solutions. Figure 2 As shown, with the increase of solvent polarity, the UV-visible absorption spectrum of compound pDCz-BP did not show obvious changes.

[0069] Example 8: UV-visible light absorption performance test of the compound pSCz-BP in Example 2 in different solutions. The compound pSCz-BP was dissolved in n-hexane, toluene, dichloromethane, tetrahydrofuran, acetonitrile and methanol solutions (all with a concentration of 10 -5 M), and use UV-visible absorption spectrometer to test its UV-visible light absorption performance in different solutions. Figure 3 As shown, the UV-visible absorption spectrum of compound pSCz-BP did not show obvious changes with the increase of solvent polarity.

[0070] Example 9: Photoluminescence performance test of the compound pDCz-BP in Example 1 in different solutions. The compound pDCz-BP was dissolved in n-hexane, toluene, chloroform, tetrahydrofuran, acetonitrile and methanol solutions (all with a concentration of 10 -5 M), and the photoluminescence spectra in different solutions were tested using a fluorescence spectrophotometer. Figure 4 As shown, the solution fluorescence of the compound pDCz-BP in different solvents is all in the near-ultraviolet region, and the half-peak width of the fluorescence spectrum is very narrow, which has the typical characteristics of multi-resonance materials.

[0071] Example 10: Photoluminescence performance test of the compound pSCz-BP in Example 2 in different solutions. The compound pSCz-BP was dissolved in n-hexane, toluene, dichloromethane, tetrahydrofuran, acetonitrile and methanol solutions (all with a concentration of 10 - 5 M), and the photoluminescence spectra in different solutions were tested using a fluorescence spectrophotometer. Figure 5 As shown, the solution fluorescence of the compound pSCz-BP in different solvents is all in the near-ultraviolet violet region, and the half-peak width of the fluorescence spectrum is very narrow, which has the typical characteristics of multi-resonance materials.

[0072] Example 11: The steps for preparing the organic light emitting diode in this example are as follows:

[0073] Step 11-1, clean the conductive ITO glass with a cleaning agent, dry it, treat it with ozone for 30 minutes, and transfer it to a glove box filled with nitrogen for later use;

[0074] Step 11-2, under high vacuum (1X 10 -6Pa) environment, HAT-CN hole injection layer, TAPC hole transport layer, TCTA electron blocking layer, mCP electron blocking layer, light-emitting layer, DPEPO hole blocking layer, TmPyPb electron transport layer, LiF electron injection layer and Al cathode layer purchased from Xi'an Yuri Solar Energy Company are sequentially deposited on the ITO anode layer; wherein the light-emitting layer includes the main materials PPF (95%) and pDCz-BP (5%). The structure of the organic electroluminescent diode device thus prepared is: ITO / HAT-CN (5nm) / TAPC (20nm) / TCTA (5nm) / mCP (5nm) / light-emitting layer (20nm) / PPF (5nm) / TmPyPb (40nm) / LiF (1nm) / Al (200nm);

[0075] Step 11-3, testing of OLED devices: After the overall production of the device is completed, the vacuum chamber of the vacuum coating machine needs to cool down naturally for 30 minutes, and then turn off the molecular pump and mechanical pump in turn. Finally, take out the device from the vacuum chamber, and use the spectrophotometer CS200 and the power supply meter Keithley 236 to test the device voltage-current-brightness data. Then use the spectrophotometer PR705 to test the device's electroluminescence spectrum (EL) and color coordinates (CIE). Use the above data to calculate the current density, current efficiency, power efficiency and external quantum efficiency of the device under different driving voltages, and obtain key performance data such as current density-voltage-brightness, current density-external quantum efficiency and electroluminescence spectrum.

[0076] Example 12: The steps for preparing an organic light-emitting diode in this example are based on Example 11, except that step 11-2 is replaced by step 12-2: in a high vacuum (1×10 -6 In a 100% Pa (1% NaCl) environment, a HATCN hole injection layer, a TAPC hole transport layer, an mCP electron blocking layer, a light-emitting layer, a DPEPO hole blocking layer, a TmPyPB electron transport layer, a TCTA electron blocking layer, a LiF electron injection layer and an Al cathode layer are sequentially deposited on the ITO anode layer; wherein the light-emitting layer comprises the main materials PPF (90%) and pSCz-BP (10%). The structure of the obtained organic light-emitting diode device is: ITO / HAT-CN (5nm) / TAPC (20nm) / TCTA (5nm) / mCP (5nm) / light-emitting layer (20nm) / PPF (5nm) / TmPyPb (40nm) / LiF (1nm) / Al (200nm).

[0077] Figure 6-7 1 is the device structure and energy level diagram of the above embodiment. Figure 8 and Fig. 9The current density-voltage-brightness curves of the organic light-emitting diodes obtained in the above-mentioned embodiment 11 and embodiment 12 are shown in the figure. It can be seen from the figure that the turn-on voltages of the organic light-emitting diodes of embodiments 11 and 12 are 4V and 3.5V respectively; the current density reaches 186.4mA / cm 2 and 261.2mA / cm 2 ; The maximum brightness reaches 472.8cd / m 2 , 545.1cd / m 2 .

[0078] Fig.10 The graph is a brightness-external quantum efficiency curve of the organic light-emitting diodes of Examples 11 and 12. As can be seen from the graph, the maximum external quantum efficiencies of the organic light-emitting diodes of Examples 11 and 12 are 3.94% and 2.44% respectively, which are diode devices with relatively high efficiency in near-ultraviolet devices.

[0079] Fig.11 The electroluminescence spectra of the organic electroluminescent diodes of Examples 11 and 12 are shown in the figure. As can be seen from the figure, the maximum emission wavelength and emission half-peak width of the organic electroluminescent diodes of Examples 11 and 12 are 419nm, 417nm and 35nm, 45nm, respectively, and the emission half-peak width is less than 50nm, which is a very good narrow-band luminescent body. It can be seen that pDCz-BP and pSCz-BP are good material options for high-definition display technology.

[0080] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A multi-resonance small molecule luminescent material, It is characterized in that The chemical structure of the multi-resonance organic small molecule luminescent material is shown in formula (1): Among them, R 1 -R 4 Each is independently one of hydrogen, an alkyl group having 1 to 10 carbon atoms, a cyano group, a C5-C25 phenyl group having at least one substituent or no substituent, or a heteroaryl group; The substituent is selected from an alkyl group having 1 to 10 carbon atoms.

2. The multi-resonance small molecule luminescent material according to claim 1, It is characterized in that R 1 -R 4 Each is independently one of hydrogen, an alkyl group having 1 to 10 carbon atoms, a cyano group, a C5-C15 phenyl group having at least one substituent or no substituent, or a heteroaryl group; The substituent is selected from an alkyl group having 1 to 10 carbon atoms; The heteroatom on the heteroaryl group is selected from at least one of O, N, and S.

3. The multi-resonance small molecule luminescent material according to claim 2, It is characterized in that R 1 -R 4 Each is independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or a C5-C15 aryl group having at least one substituent or no substituent; The substituents are selected from alkyl groups having 1 to 6 carbon atoms.

4. The multi-resonance small molecule luminescent material according to claim 3, It is characterized in that R 1 -R 4 Each is independently hydrogen, an alkyl group having 1 to 5 carbon atoms, or a phenyl group having at least one substituent or no substituent; the substituent is selected from an alkyl group having 1 to 5 carbon atoms.

5. The multi-resonance small molecule luminescent material according to claim 4, It is characterized in that R 1 -R 4 is hydrogen, tert-butyl or phenyl having at least one substituent or no substituent; The substituent is tert-butyl.

6. The multi-resonance small molecule luminescent material according to claim 1, It is characterized in that The material is selected from the following structures:

7. The multi-resonance small molecule luminescent material according to any one of claims 1 to 6, It is characterized in that The range of the steady-state fluorescence spectrum of the multi-resonance small molecule luminescent material in a toluene solution is 380-800 nm, and the half-peak width is less than or equal to 40 nm.

8. An organic light emitting diode, It is characterized in that The light-emitting layer of the diode comprises at least one of the materials described in any one of claims 1 to 6.

9. The organic light emitting diode according to claim 8, It is characterized in that The diode comprises an anode layer, a hole injection layer, at least one hole transport layer, a light emitting layer, at least one electron transport layer, an electron injection layer and a cathode layer which are stacked in sequence.

10. The organic light emitting diode according to claim 9, It is characterized in that The mass percentage of the multi-resonance small molecule luminescent material in the luminescent layer is 0.1%-20%. The thickness of the light emitting layer ranges from 10 nm to 200 nm.

11. Use of the multi-resonance organic small molecule luminescent material according to any one of claims 1 to 6 in electroluminescence.

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