Polycyclic aromatic compound and electroluminescent device thereof

Abstract

The invention belongs to the technical field of organic light-emitting materials and semiconductors, and provides a polycyclic aromatic compound and an electroluminescent device thereof, the structural formula of the polycyclic aromatic compound is # imgabs0 #, the polycyclic aromatic compound is applied to a light-emitting layer of an OLED device as a guest light-emitting material, the starting voltage of the electroluminescent device can be effectively reduced, and the light-emitting efficiency of the OLED device is improved. The luminous efficiency is improved, and the service life of the electroluminescent device is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical fields of organic light-emitting materials and semiconductors, and particularly relates to a polycyclic aromatic compound and an electroluminescent device thereof. Background Art

[0002] An organic light-emitting diode (OLED) is a current-type semiconductor light-emitting device based on organic materials. OLED devices have the characteristic of self-luminescence and do not require a backlight. Therefore, they have the advantages of high contrast, thin thickness, wide viewing angle, fast response speed, and can be used for flexible panels. These advantages of OLED devices make them a popular research direction in the fields of lighting and display.

[0003] For traditional OLED materials, such as fluorescent materials, the luminous efficiency is limited by the spin statistics law, and the theoretical upper limit of the internal quantum efficiency is 25%. Although phosphorescent materials can achieve triplet exciton luminescence through the strong spin-orbit coupling of heavy metal atoms, making the internal quantum efficiency close to 100%, there are problems such as high cost, poor stability, and insufficient color purity due to a relatively wide spectrum. With the continuous improvement of the performance requirements for OLED devices, such as higher luminous efficiency, better color purity, and longer lifespan, new OLED materials need to be developed to meet these continuously improving performance requirements.

[0004] Multiresonant OLED materials are a new type of materials that achieve efficient luminescence through molecular structure design and mechanisms such as vibronic coupling. Multiresonant OLED materials can effectively break through the limitations of traditional luminescence mechanisms, achieve narrow-spectrum emission while improving the luminous efficiency, and are expected to solve the problems faced by traditional OLED materials. Therefore, they have become one of the hot research directions in current OLED material research.

[0005] Although multiresonant OLED materials have many advantages, there are also some problems in practical applications, mainly including the following aspects: Although multiresonant OLED materials theoretically have high luminous efficiency, in practical applications, due to the influence of various factors, such as intermolecular interactions and losses during energy transfer processes, their actual luminous efficiency still does not reach the ideal state, and the molecular structure design of the materials needs to be further optimized; Secondly, due to the characteristics of multiresonant OLED materials themselves, the driving voltage of OLED devices is relatively high; Moreover, when OLED devices operate, certain heat will be generated. Some multiresonant OLED materials may exhibit phenomena such as increased molecular thermal motion and crystallization at high temperatures, which will damage the ordered structure of the materials, affect carrier transport and luminous efficiency, and shorten the lifespan of OLED devices.

[0006] The US patent application with the publication number US2022 / 0077406A1 discloses , , , Multi-resonant OLED materials. When these multi-resonant OLED materials are used as guest materials in OLED devices, although the driving voltage can be reduced and the luminous efficiency can be improved to a certain extent, the lifespan of the OLED device is still insufficient. SUMMARY OF THE INVENTION

[0007] To solve the problems of the above-mentioned prior art, the present invention provides a polycyclic aromatic compound and an electroluminescent device thereof, which solve the problems of unsatisfactory luminous efficiency, high driving voltage, and insufficient device lifespan of the existing multi-resonant OLED materials.

[0008] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a polycyclic aromatic compound, and the structural formula of the polycyclic aromatic compound is shown as formula (1):

[0009] In the formula: R1 and R2 are each independently selected from H, cyano, trifluoromethyl, C1-C6 alkyl, and C6-C 12 aryl, and the bonding modes of R1 and R2 with the main structure are both single-bond bonding, and the main structure is ; Y is selected from -SiCH3, -SiPh, n-BuGe-, and -P=O; X is selected from H and C6-C 20 deuterated aromatic secondary amine; A is selected from carbonyl and substituted or unsubstituted C6-C 12 aryl, B is substituted or unsubstituted C6-C 12 aryl, and A and B are different; when A is carbonyl, " " is the carbon atom in the carbonyl, or " " is a single bond, and the carbon atom in the carbonyl is at the 2nd or 3rd position in the main structure; when A is substituted or unsubstituted C6-C 12 aryl, " " is a chemical bond; B can be called ring B, and when A is substituted or unsubstituted C6-C 12 aryl, it can be called ring A; Z1 and Z2 are each independently selected from , , , , , , , , , , and , wherein, in Z1, " " indicates that Z1 is bonded to the corresponding benzene ring and the 3-position in the main structure by a single bond, and in Z2, " " indicates that Z2 is bonded to the corresponding benzene ring and B in the main structure by a single bond; Z1 and Z2 are different.

[0010] In the present invention, Ph in -SiPh refers to phenyl, and n-Bu in n-BuGe- refers to n-butyl.

[0011] In some preferred embodiments of the present invention, Y is selected from -SiCH3, n-BuGe-, and -P=O; X is a deuterated aromatic secondary amine of C6~C 20 .

[0012] In some other preferred embodiments of the present invention, X is H.

[0013] Preferably, the C1~C6 alkyl group in the present invention is selected from methyl and tert-butyl.

[0014] Preferably, the substituted or unsubstituted C6~C 12 aryl group in the present invention means that the C6~C 12 aryl group can be further substituted by a substituent or can be unsubstituted; when the C6~C 12 aryl group is substituted by a substituent, the substituent is selected from methyl, ethyl, propyl, and tert-butyl; the C6~C 12 aryl group is preferably phenyl.

[0015] Preferably, the deuterated aromatic secondary amine of C6~C 20 in the present invention is selected from and , wherein, " " indicates the bonding position of X to the main structure.

[0016] Preferably, the polycyclic aromatic compound in the present invention is selected from one of the following compounds 1 to 112: .

[0017] In a second aspect, the present invention provides an electroluminescent device comprising a cathode, an anode, and an organic layer located between the cathode and the anode, wherein the organic layer comprises a hole transport layer (HTL), an emission material layer (EML), and an electron transport layer (ETL), wherein the hole transport layer is located between the anode and the emission layer, and the electron transport layer is located between the cathode and the emission layer; components of the emission layer include a host luminescent material and a guest luminescent material, and the guest luminescent material includes a polycyclic aromatic compound as shown in formula (1).

[0018] Preferably, the guest luminescent material of the present invention is any one of compounds 1 to 112 of the present invention.

[0019] Preferably, the mass of the guest luminescent material of the present invention accounts for 1% to 3% of the mass of the luminescent layer.

[0020] Preferably, the host luminescent material of the present invention is selected from , , , and .

[0021] Preferably, a substrate may be disposed outside the anode, and a cover layer may be disposed outside the cathode. The substrate may be a glass or polymer material with excellent mechanical strength, thermal stability, water resistance, and transparency, such as ITO conductive glass. Furthermore, the substrate used for a display may also include a thin film transistor (TFT) array and a specific display image formed by the array.

[0022] Preferably, the anode is a material with a large work function to facilitate hole injection into the organic layer. Anode materials that can be used in the present invention include indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), and the like.

[0023] Preferably, for the cathode, in order to facilitate the injection of electrons into the organic layer, a material with a small work function is preferred. The cathode materials that can be used in the present invention include: magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), and alloys formed by any combination or arbitrary combination thereof.

[0024] Preferably, the hole transport layer can be a single-layer hole transport layer, that is, a single-layer hole transport layer containing only one compound (having both hole injection function and hole transport effect), or a composite hole transport layer containing multiple compounds. The composite hole transport layer is composed of multiple organic hole materials, and is mainly arranged in the general layout mode of the industry, namely the hole injection layer (Hole Inject Layer, HIL), the hole transport layer, and the electron blocking layer (Electron Blocking Layer, EBL). In the present invention, the hole injection layer is preferably a p-doped hole injection layer, and the p-doped hole injection layer means a hole injection layer doped with a p-dopant. The p-dopant is a material that can endow p-type semiconductor characteristics. The p-type semiconductor characteristics mean the characteristics of injecting or transporting holes at the HOMO energy level, that is, the characteristics of having a high hole conductivity.

[0025] Preferably, the electron transport layer is a composite electron transport layer, which sequentially includes an electron injection layer, an electron transport layer, and a hole blocking layer. The material of the electron transport layer can be selected from one or more combinations of E1, E2, and E3 with excellent performance in the industry.

[0026] In some specific embodiments of the present invention, the electroluminescent device sequentially includes an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode.

[0027] In a third aspect, the present invention provides a display panel, which includes the electroluminescent device of the present invention.

[0028] Compared with the prior art, the present invention has the following beneficial effects: First, in the structure of the polycyclic aromatic compound of the present invention, A and B are different, and Z1 and Z2 are different, so that the two six-membered rings where the heteroatoms Ge, Si or P are located are asymmetrically connected with the midline of the two six-membered rings as the axis. Since the atomic radius of the heteroatoms Ge, Si or P is larger than that of the B atom, the larger Ge, Si or P atoms will cause a certain distortion and deformation of the conjugated structure of the molecule. This structural change can not only adjust the distribution of the frontier orbitals of the molecule, and then control the emission wavelength, but also prompt the molecule to absorb light of a specific wavelength and efficiently convert it into visible light emission, thereby achieving a high luminous efficiency. Secondly, the heterocyclic system containing P, Ge or Si atoms and N atoms has a strong electron-withdrawing effect, resulting in a small overlap of the frontier orbitals between the electron donors connected thereto, achieving a small energy level difference between the S1 state (singlet excited state) and the T1 state (triplet excited state), so that reverse intersystem crossing can be achieved under thermal stimulation conditions, thereby prolonging the luminescence lifetime of the compound and improving the luminous efficiency. Thirdly, in the structure of the polycyclic aromatic compound of the present invention, the benzene ring is bonded to A and B through Z1 and Z2 respectively, and the groups connected by Z1 and Z2 form stereoisomers with the entire compound structure. This design not only improves the rigidity of the compound, reduces the vibration and rotation within the compound, reduces the probability of non-radiative transition, and enables more excited state energy to be released in the form of radiative transition, thereby improving the luminous efficiency, but also improves the thermal stability of the compound, ensures that the compound still maintains a stable structure and luminescence performance at a higher temperature, and prolongs the luminescence lifetime of the compound. Through performance testing, it is proved that applying the polycyclic aromatic compound of the present invention as the guest luminescent material to the light-emitting layer of an OLED device can effectively reduce the turn-on voltage of the electroluminescent device, improve the luminous efficiency, and prolong the service life of the electroluminescent device.

[0029] The electroluminescent device of the present invention uses the polycyclic aromatic compound as the guest luminescent material, and has a lower turn-on voltage, a higher luminous efficiency, and a longer service life. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for describing the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0031] Figure 1 It is a cross-sectional view of the organic electroluminescent device of the present invention; Figure 2 It is the nuclear magnetic spectrum of compound 1 synthesized in Preparation Example 1 of the present invention; Figure 3 It is the nuclear magnetic spectrum of compound 2 synthesized in Preparation Example 2 of the present invention; Figure 4 It is the NMR spectrum of compound 57 synthesized in Preparation Example 4 of the present invention; Figure 5 It is the NMR spectrum of compound 86 synthesized in Preparation Example 5 of the present invention.

[0032] Explanation of reference numerals: 1 - Substrate, 2 - Anode, 3 - Hole injection layer, 4 - Hole transport layer, 5 - Electron blocking layer, 6 - Light emitting layer, 7 - Hole blocking layer, 8 - Electron transport layer, 9 - Electron injection layer, 10 - Cathode, 11 - Covering layer. Detailed implementation manners

[0033] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] It should be noted that the process equipment or devices not specifically noted in the following examples all adopt conventional equipment or devices in the art.

[0035] The synthesis processes of compounds 1 - 112 of the present invention are as follows.

[0036] The structures of important reactants L1 - L23, X1 and X2 involved in the present invention are as shown below:

[0037] Preparation Example 1 (Synthesis of Compound 1)

[0038] Step 1: Operation procedure: Under nitrogen protection, add 1-bromo-2,6-difluorobenzene (19 g, 0.1 mol), reactant L1 (32 g, 0.1 mol), cesium carbonate (41 g, 0.125 mol), and 200 mL of DMF into a 500 mL three-necked flask. Start stirring, heat the reaction solution to 130 °C, and continue the reaction for 8 h. After the reaction is completed, cool the reaction solution to room temperature, add dichloromethane and purified water for washing. After liquid separation, retain the organic phase. The aqueous phase is continuously extracted with dichloromethane, and the organic phases are combined. The organic phase is dried with anhydrous magnesium sulfate, concentrated, and purified by silica gel column chromatography (petroleum ether / dichloromethane = 5:1) to obtain compound 1-1, weighing 45 g, with a yield of 91%, HPLC (High Performance Liquid Chromatography) purity of 98%, and LC-MS (Liquid Chromatograph-Mass Spectrometer) showing a molecular weight of 496.2.

[0039] Step 2: Operation procedure: Refer to the synthesis process of compound 1-1. Replace 1-bromo-2,6-difluorobenzene with compound 1-1 (25 g, 0.05 mol), and replace reactant L1 (32 g, 0.1 mol) with reactant L3 (16.6 g, 0.05 mol) to obtain compound 1-2, weighing 35 g, with a yield of 88%, HPLC purity of 98%, and LC-MS showing a molecular weight of 807.3.

[0040] Step 3: Operation procedure: Under nitrogen protection, add 150 mL of tert-butylbenzene solution containing compound 1-2 (16.1 g, 0.02 mol) into a 500 mL three-necked flask. Start stirring, cool the system to -40 °C, and dropwise add a n-hexane solution of 2.5 M sec-butyl lithium (sec-BuLi) (9.6 mL, 0.024 mol). Heat the reaction solution to 50 °C, stir for 1 hour, and stop the reaction. Concentrate the reaction solution at low temperature to remove low-boiling n-hexane. Cool the reaction solution to -40 °C again, add trichlorophenylsilane (PhSiCl3) (6.3 g, 0.03 mol), transfer the reaction solution to room temperature and react for 1 h, and dropwise add N,N-diisopropylethylamine (Ethyldiisopropylamine, DIEA, EtN(iPr)2) (6.2 g, 0.048 mol) at room temperature. After the addition is complete, slowly heat the reaction solution to 160 °C and continue the reaction for 18 h until the reaction is complete. After the reaction is completed, cool the reaction solution to room temperature and concentrate. The residue is purified by silica gel column chromatography (petroleum ether / dichloromethane = 3:1) to obtain compound 1, weighing 9.3 g, with a yield of 56%, HPLC content of 99%, and LC-MS showing a molecular weight of 829.4. The NMR spectrum of compound 1 is asFigure 2 as shown

[0041] 1H NMR data of Compound 1: 1 H NMR (500 MHz, CD3OD ) 1 H NMR (500 MHz, Chloroform) δ 8.12 (s, 2H), 7.90 (s, 2H), 7.45 (d, J J = 5.0 Hz, 3H), 7.41 – 7.28 (m, 8H), 7.20 (dd, J J = 20.7, 15.7 Hz, 5H), 7.07 (t, J J = 10.0 Hz, 3H), 7.00 (s, 1H), 6.94 (d, J J = 5.0 Hz, 4H), 1.69 (s, 6H), 1.30 (d, J J = 20.0 Hz, 18H). Preparation Example 2 (Synthesis of Compound 2)

[0042] Step 1: Procedure: Referring to the synthesis process from Compound 1-1 to Compound 1-2, replace the reactant L3 (16.6 g, 0.05 mol) with the reactant L4 (16.7 g, 0.05 mol) to obtain Compound 2-1, weighing 36 g, with a yield of 89% and an HPLC purity of 98%. LC-MS shows a molecular weight of 807.3.

[0043] Step 2: Procedure: Referring to the synthesis process from Compound 1-2 to Compound 1, replace Compound 1-2 (16.1 g, 0.02 mol) with Compound 2-1 (16.2 g, 0.02 mol), and replace trichlorophenylsilane (6.3 g, 0.03 mol) with trichloromethylsilane (4.5 g, 0.03 mol) to obtain Compound 2, weighing 8.9 g, with a yield of 58% and an HPLC purity of 99%. LC-MS shows a molecular weight of 769.4. The 1H NMR spectrum of Compound 2 is as Figure 3 shown

[0044] 1H NMR data of Compound 2: 1 H NMR (500 MHz, CD3OD) δ 7.45 (s, 1H), 7.38 – 7.15 (m, 12H), 7.08 (dd, J= 17.5, 7.5 Hz, 7H), 7.02 – 6.90 (m, 5H), 1.69 (s,6H), 1.32 (s, 9H), 1.28 (s, 9H), 0.66 (s, 3H). Preparation Example 3 (Synthesis of Compound 39)

[0045] Procedure: The synthesis process of Compound 39 refers to the synthesis process of Compound 1-2 to Compound 1. Replace trichlorophenylsilane (6.3 g, 0.03 mol) with trichlorobutylgermane (7.1 g, 0.03 mol) to obtain Compound 39, with a weight of 9.7 g, a yield of 57%, an HPLC purity of 99%, and LC-MS showing a molecular weight of 855.4.

[0046] Preparation Example 4 (Synthesis of Compound 57)

[0047] Step 1: Procedure: Refer to the synthesis process of Compound 1-1. Replace reactant L1 (32 g, 0.1 mol) with reactant L2 (45 g, 0.2 mol) to obtain Compound 57-1, with a weight of 35 g, a yield of 89%, an HPLC purity of 98%, and LC-MS showing a molecular weight of 400.0.

[0048] Step 2: Procedure: Refer to the synthesis process of Compound 1-1 to Compound 1-2. Replace Compound 1-1 (25 g, 0.05 mol) with Compound 57-1 (19.9 g, 0.05 mol) to obtain Compound 57-2, with a weight of 31 g, a yield of 86%, an HPLC purity of 98%, and LC-MS showing a molecular weight of 711.2.

[0049] Step 3: Procedure: Under nitrogen protection, add 400 mL of toluene solution containing compound 57-2 (35 g, 0.05 mol) into a 1000 mL three-necked flask. Start stirring, cool the system to -40 °C, and dropwise add a hexane solution of 1.6 M sec-butyllithium (38 mL, 0.05 mol). Slowly warm the reaction solution to 50 °C and stir it for 2 hours under heating. Cool the reaction solution to -10 °C, and dropwise add phosphorus trichloride (PCl3) (16 mL, 0.075 mol). After the addition is complete, heat the reaction solution to 80 °C and react for 1 h. Add 3.5 g of sublimed sulfur (S8) and continue to react for 1 h. Cool the reaction solution to -40 °C again, add AlCl3 (81 g, 0.25 mol) and DIEA (23 g, 0.18 mol), then warm the reaction solution to 110 °C and continue to react for 12 h until the reaction is complete. Cool the reaction solution to room temperature and concentrate it. The residue is purified by silica gel column chromatography (methyl petroleum ether / dichloromethane = 2:1) to obtain compound 57-3, weighing 19 g, with a yield of 56%, an HPLC content of 98%, and LC-MS showing a molecular weight of 691.2.

[0050] Step 4: Procedure: Under nitrogen protection, add compound 57-3 (13.8 g, 0.02 mol) and 100 mL of dichloromethane into a 250 mL three-necked flask. Start stirring, cool the system to -15 °C, and slowly add m-CPBA (m-Chloroperbenzoic Acid) (5.5 g, 0.032 mol). React for 1 h until the reaction is complete. Transfer the reaction solution to room temperature, add saturated aqueous sodium sulfite solution (10.0 mL), stir and react for 1 h, remove the insoluble matter, and separate the layers. Remove the solvent by distillation under reduced pressure. The residue is purified by silica gel column chromatography (petroleum ether / dichloromethane = 2:1) to obtain compound 57, weighing 8.2 g, with a yield of 61%, an HPLC purity of 99%, and LC-MS showing a molecular weight of 675.2. The NMR spectrum of compound 57 is as Figure 4 shown.

[0051] 1H NMR data of compound 57: 1 H NMR (500 MHz, CD3OD ) δ 7.88 (t, J = 16.7 Hz,5H), 7.65 (d, J = 15.0 Hz, 2H), 7.52 – 7.13 (m, 14H), 7.03 (d, J = 5.0 Hz, 3H),6.94 (s, 1H), 0.66 (s, 6H). Preparation Example 5 (Synthesis of Compound 86)

[0052] Step 1: Operation process: Under nitrogen protection, add 2,5-dibromo-1,3-difluorobenzene (82 g, 0.3 mol), reactant X1 (53 g, 0.3 mol) and 1000 mL of toluene into a 2000 mL three-necked flask. Stir until the solution is clear, then add Pd2(dba)3 (5.5 g, 6 mmol), Am-phos ([(4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine) (4.0 g, 15 mmol), and sodium tert-butoxide (58 g, 0.6 mol). Heat the reaction solution to 120 °C and continue the reaction for 10 h. After the reaction is completed, filter while hot using diatomaceous earth. Cool the filtrate to room temperature, add purified water for washing, separate the layers, and retain the organic phase. Then extract the aqueous phase with ethyl acetate. Combine the organic phases, dry the organic phase with anhydrous magnesium sulfate, concentrate, and purify by silica gel column chromatography (dichloromethane / petroleum ether = 1:3) to obtain compound 86-1, weighing 84 g, with a yield of 76%, an HPLC content of 98%, and LC-MS showing a molecular weight of 366.0.

[0053] Step 2: Operation process: Refer to the synthesis process of compound 1-1, replace compound 1-1 (25 g, 0.05 mol) with compound 86-1 (37 g, 0.1 mol) to obtain compound 86-2, weighing 61 g, with a yield of 91%, an HPLC purity of 98%, and LC-MS showing a molecular weight of 667.3.

[0054] Step 3: Operation process: Refer to the synthesis process of compound 1-1, replace compound 1-1 (25 g, 0.05 mol) with compound 86-2 (33 g, 0.05 mol) to obtain compound 86-3, weighing 44 g, with a yield of 89%, an HPLC purity of 98%, and LC-MS showing a molecular weight of 978.4.

[0055] Step 4: Operation process: Refer to the synthesis process from compound 57-2 to compound 57-3 for the synthesis of compound 86-4. Replace compound 57-2 (35 g, 0.05 mol) with compound 86-3 (19.6 g, 0.02 mol) to obtain compound 86-4, weighing 11.9 g, with a yield of 62%, an HPLC content of 98%, and LC-MS showing a molecular weight of 960.4.

[0056] Step 5: Operation process: The synthesis process of compound 86 refers to the synthesis process of compound 57-3 to compound 57. Replace compound 57-2 (13.8 g, 0.02 mol) with compound 86-4 (19.2 g, 0.02 mol) to obtain compound 86, weighing 11.7 g, with a yield of 62% and an HPLC content of 99%. LC-MS shows a molecular weight of 944.5. The NMR spectrum of compound 86 is as shown in Figure 5 shown below.

[0057] 1H NMR data of compound 86: 1 H NMR (500 MHz, CD3OD ) δ 13.45 (s, 2H), 8.01(s, 1H), 7.90 (s, 2H), 7.64 (s, 1H), 7.45 (s, 1H), 7.34 (s, 2H), 7.28 – 7.05(m, 8H), 7.04 – 6.88 (m, 3H), 6.57 (s, 1H), 6.39 (s, 1H), 1.69 (s, 6H), 1.30(d, J = 20.0 Hz, 18H). The synthesis of other compounds all refers to the synthesis processes of Preparation Examples 1 to 5, and can be replaced with the corresponding reactants L1 to L33, X1 and X2.

[0058] The compositions and mass spectrometry data of some of these compounds are shown in Table 1:

[0059] Based on the above polycyclic aromatic compounds (compounds 1 to 112), as the guest luminescent material, an electroluminescent device is prepared. Among them, the structural schematic diagram of the electroluminescent device is as shown in Figure 1 shown below, including a substrate 1, an anode 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9, a cathode 10 and a cover layer. The preparation method of the electroluminescent device adopts the device preparation process technology generally recognized in the current industry.

[0060] Comparative Examples 1 to 4 Prepare the electroluminescent device according to the following steps: Under high vacuum conditions, indium tin oxide with a thickness of 25 nm is successively evaporated on a cleaned conductive glass (as substrate 1) as anode 2, a mixture of 10 nm of HT-1 and P-1 (used as p-dopant, with a mass ratio of 97:3) is evaporated as hole injection layer 3, HT-1 with a film thickness of 50 nm is evaporated as hole transport layer 4, EB-1 with a film thickness of 10 nm is evaporated as electron blocking layer 5. After the evaporation of the electron blocking layer, a light-emitting layer 6 with a film thickness of 30 nm is fabricated. The light-emitting layer 6 uses PH-4 as the host luminescent material and is combined with one of BD0X (Comparative Example 1), BD01 (Comparative Example 2), BD02 (Comparative Example 3), or BD03 (Comparative Example 4) as the guest luminescent material, and the mass ratio of the host luminescent material to the guest luminescent material is 98:2. On the light-emitting layer, HB-1 with a film thickness of 16 nm is evaporated as hole blocking layer 7. On the hole blocking layer, E1 is evaporated, and the vacuum evaporation film thickness of this material is 25 nm as electron transport layer 8. On the electron transport layer, a LiQ (lithium 8-hydroxyquinoline) layer with a film thickness of 10 nm is fabricated through a vacuum evaporation device, and the LiQ layer is electron injection layer 9. On the electron injection layer, an Al electrode layer with a film thickness of 50 nm is fabricated through a vacuum evaporation device, and this layer is cathode 10. Finally, after evaporating the covering material X, encapsulation is carried out to complete the preparation process of the electroluminescent device. The electroluminescent device shown in Figure 1 is obtained by this method.

[0061] The detailed preparation schemes of the electroluminescent devices of Comparative Examples 1 to 4 are as follows: Comparative Example 1: Indium tin oxide (25 nm) / HT-1:P-1 = 97:3 (10 nm) / HT-1 (50 nm) / EB-1 (10 nm) / PH-4:BD0X = 98:2 (30 nm) / HB-1 (16 nm) / E1 (25 nm) / LiQ (10 nm) / Al (50 nm); Comparative Example 2: Indium tin oxide (25 nm) / HT-1:P-1 = 97:3 (10 nm) / HT-1 (50 nm) / EB-1 (10 nm) / PH-4:BD01 = 98:2 (30 nm) / HB-1 (16 nm) / E1 (25 nm) / LiQ (10 nm) / Al (50 nm); Comparative Example 3: Indium tin oxide (25 nm) / HT-1:P-1 = 97:3 (10 nm) / HT-1 (50 nm) / EB-1 (10 nm) / PH-4:BD02 = 98:2 (30 nm) / HB-1 (16 nm) / E1 (25 nm) / LiQ (10 nm) / Al (50 nm); Comparative Example 4: Indium Tin Oxide (25 nm) / HT-1:P-1 = 97:3 (10 nm) / HT-1 (50 nm) / EB-1 (10 nm) / PH-4:BD03 = 98:2 (30 nm) / HB-1 (16 nm) / E1 (25 nm) / LiQ (10 nm) / Al (50 nm).

[0062] Examples 1 to 3 Prepared according to the preparation method of Comparative Example 1, except that the guest luminescent material BD0X was replaced with Compound 1 of the present invention, and the mass ratios of the host luminescent material to the guest luminescent material were 97:3 (Example 1), 99:1 (Example 2), and 98:2 (Example 3) in sequence.

[0063] The detailed preparation schemes of the electroluminescent devices of Examples 1 to 3 are as follows: Example 1: Indium Tin Oxide (25 nm) / HT-1:P-1 = 97:3 (10 nm) / HT-1 (50 nm) / EB-1 (10 nm) / PH-4:Compound 1 = 97:3 (30 nm) / HB-1 (16 nm) / E1 (25 nm) / LiQ (10 nm) / Al (50 nm); Example 2: Indium Tin Oxide (25 nm) / HT-1:P-1 = 97:3 (10 nm) / HT-1 (50 nm) / EB-1 (10 nm) / PH-4:Compound 1 = 99:1 (30 nm) / HB-1 (16 nm) / E1 (25 nm) / LiQ (10 nm) / Al (50 nm); Example 3: Indium Tin Oxide (25 nm) / HT-1:P-1 = 97:3 (10 nm) / HT-1 (50 nm) / EB-1 (10 nm) / PH-4:Compound 1 = 98:2 (30 nm) / HB-1 (16 nm) / E1 (25 nm) / LiQ (10 nm) / Al (50 nm).

[0064] Examples 4 to 33 Prepared according to the preparation method of Comparative Example 1, except that the guest luminescent material BD0X was sequentially replaced with the preferred compounds of the present invention, and the mass ratio of the host luminescent material to the guest luminescent material was 98:2. The specific compound names for replacement are shown in Table 2 below.

[0065]

[0066] The structures of some materials used in the preparation process of the above electroluminescent devices are as follows:

[0067] Data collection on the display performance of the electroluminescent devices prepared in the above comparative examples and the embodiments of the present invention was carried out, and the collected data is shown in Table 3 below.

[0068]

[0069] It can be seen from the data in Table 3 that, compared with Pro.1 - Pro.4 using BD0X, BD01, BD02, and BD03 as the host luminescent materials, in Ex.1 - Ex.33 using the polycyclic aromatic compounds of the present invention as the host luminescent materials, the driving voltage of the electroluminescent devices decreases, the service life is significantly prolonged, and the current efficiency increases. It shows that replacing B with heteroatoms Ge, Si, or P and forming an asymmetric structure with the midline of the two six - membered rings where Ge, Si, or P is located can improve the luminescence efficiency of OLED devices and prolong the service life when using polycyclic aromatic compounds as the host luminescent materials.

[0070] Compared with Pro.1 - Pro.4 using BD0X (green light) and BD01 - BD03 (blue light) as the host luminescent materials, the emission wavelengths of the compounds in Ex.1 - Ex.27, Ex.29 - Ex.30, Ex.32 - Ex.33 using the polycyclic aromatic compounds of the present invention as the host luminescent materials are in the range of blue light to violet light, and the wavelengths are significantly blue - shifted.

[0071] Compared with Ex.1 - Ex.27, Ex.29 - Ex.30, Ex.32 - Ex.33, the emission wavelengths of the compounds in Ex.28 and Ex.31 are significantly red - shifted. This may be because the corresponding compounds 61 and 101 in Ex.28 and Ex.31 contain carbonyl groups. The double bond (C = O) in the carbonyl group contains 1 σ bond and 1 π bond, and the π electrons are in the antibonding orbital (π*). When the carbonyl group is connected to other conjugated systems (such as double bonds, benzene rings), a larger conjugated π - electron system will be formed, so the wavelength is red - shifted.

[0072] Compared with Ex.1 to Ex.28, the integrated luminescence performance of the electroluminescent devices in Ex.29 to Ex.33 has obvious advantages. This may be because the substituent X1 in the polycyclic aromatic compound used in Ex.29 to Ex.33 is a deuterated aromatic secondary amine. After introducing deuterium atoms into the compound molecule, the spin-orbit coupling effect of the compound molecule is enhanced. This will increase the intersystem crossing (ISC) ability of electrons in the compound molecule, improve the radiative transition rate of the compound molecule, and reduce the non-radiative transition rate. Thus, it is beneficial to improve the quantum efficiency of the guest luminescent material and further improve the integrated luminescence performance of the electroluminescent device.

[0073] From the data of the electroluminescent devices in Ex.1 to Ex.3, it can be seen that when the mass ratio of the guest luminescent material in the light-emitting layer is in the range of 1% to 3%, the integrated luminescence efficiency of the electroluminescent devices is similar. When the mass ratio of the guest luminescent material is 2%, the luminescence performance of the prepared electroluminescent device is slightly better than that of Example 1 and Example 2.

[0074] In summary, when the polycyclic aromatic compound described in the present invention is used as a guest luminescent material in the light-emitting layer of an OLED device, it can effectively reduce the turn-on voltage of the OLED device, improve the luminescence efficiency and service life of the OLED device.

[0075] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the spirit of the present invention.

[0076] Many other changes and modifications can be made without departing from the concept and scope of the present invention. It should be understood that the present invention is not limited to specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A polycyclic aromatic compound, characterized in that, The structural formula of the polycyclic aromatic compound is as shown in Formula (1): In the formula: R1 and R2 are each independently selected from H, cyano, trifluoromethyl, C1-C6 alkyl, and C6-C 12 aryl, and the bonding modes of R1 and R2 to the main structure are both single-bond bonding, and the main structure is ; Y is selected from -SiCH3, -SiPh, n-BuGe-, and -P=O; X is selected from H and deuterated aromatic secondary amines of C6~C 20 ; A is selected from a carbonyl group and a substituted or unsubstituted aryl group having 6 to C 12 aryl group, B is a substituted or unsubstituted aryl group having 6 to C 12 aryl group, and A and B are different; when A is a carbonyl group, " " is the carbon atom in the carbonyl group, or " " is a single bond, and the carbon atom in the carbonyl group is at the 2nd or 3rd position in the main structure; when A is a substituted or unsubstituted aryl group having 6 to C 12 aryl group, " " is a chemical bond; Z1 and Z2 are each independently selected from , , , , , , , , , , and , where " " in Z1 means that Z1 is bonded to the corresponding benzene ring and the 3-position in the main structure by a single bond, and " " in Z2 means that Z2 is bonded to the corresponding benzene ring and B in the main structure by a single bond; Z1 and Z2 are different.

2. The polycyclic aromatic compound according to claim 1, wherein, Y is selected from -SiCH3, n-BuGe-, and -P=O; X is a deuterated aromatic secondary amine having 6 to C 20 of.

3. The polycyclic aromatic compound according to claim 2, wherein, The deuterated aromatic secondary amine is selected from and , wherein " " represents the position where X is bonded to the main structure.

4. The polycyclic aromatic compound according to claim 1, wherein X is H.

5. The polycyclic aromatic compound according to claim 1, wherein The deuterated aromatic secondary amine is selected from and , wherein " " represents the position where X is bonded to the main structure.

6. The polycyclic aromatic compound according to claim 1, characterized in that, The C1-C6 alkyl group is selected from methyl and tert-butyl.

7. The polycyclic aromatic compound according to claim 1, characterized in that, The polycyclic aromatic compound is selected from one of the following compounds 1 to 112:

8. An electroluminescent device, characterized in that, It includes a cathode, an anode, and an organic layer located between the cathode and the anode. The organic layer includes a hole transport layer, a light-emitting layer, and an electron transport layer. The hole transport layer is located between the anode and the light-emitting layer, and the electron transport layer is located between the cathode and the light-emitting layer; the components of the light-emitting layer include a host light-emitting material and a guest light-emitting material, and the guest light-emitting material includes the polycyclic aromatic compound according to any one of claims 1 to 7.

9. The electroluminescent device according to claim 8, characterized in that, The mass of the guest light-emitting material accounts for 1% to 3% of the mass of the light-emitting layer.

10. The electroluminescent device according to claim 8, wherein, The host luminescent material is selected from , , , and .

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