A polycyclic aromatic compound and an electroluminescent device thereof

Abstract

The application belongs to the technical field of organic light-emitting materials and semiconductors, and provides a polycyclic aromatic compound and an electroluminescent device, wherein the structural formula of the polycyclic aromatic compound is: the polycyclic aromatic compound is applied to a light-emitting layer of an OLED device as a guest light-emitting material, can effectively reduce the starting voltage of the electroluminescent device, improve the light-emitting efficiency, and prolong the service life of the electroluminescent device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic light-emitting materials and semiconductor technology, and particularly relates to a polycyclic aromatic compound and an electroluminescent device thereof. BACKGROUND

[0002] An organic light emitting diode (OLED) is a current-driven semiconductor light-emitting device based on organic materials. The OLED device has a self-luminous characteristic and does not require a backlight, so it has the characteristics of high contrast, thin thickness, wide viewing angle, and fast response, and can be used in flexible panels. These advantages of the OLED device make it a popular research direction in the lighting and display fields.

[0003] Traditional OLED materials, such as fluorescent materials, have a theoretical internal quantum efficiency upper limit of 25% due to the limitation of spin statistics. Although phosphorescent materials can achieve triplet exciton luminescence through strong spin-orbit coupling of heavy metal atoms, making the internal quantum efficiency close to 100%, they have problems such as high cost, poor stability, and insufficient color purity due to a wide spectrum. With the increasing performance requirements of OLED devices, such as higher luminous efficiency, better color purity, and longer lifespan, new OLED materials need to be developed to meet these increasing performance requirements.

[0004] Multiple resonance OLED materials are a new type of material that can achieve efficient luminescence through molecular structure design and vibration-electron coupling mechanisms. Multiple resonance OLED materials can effectively break through the limitations of traditional luminescence mechanisms, improving luminous efficiency while achieving narrow spectrum emission, and are expected to solve the problems faced by traditional OLED materials, thus becoming one of the hot research directions in OLED materials.

[0005] Although multiple resonance OLED materials have many advantages, they also have some problems in practical applications, mainly including the following aspects: Although multiple resonance OLED materials have high theoretical luminous efficiency, in practical applications, due to various factors such as intermolecular interaction, energy transfer process loss, etc., their actual luminous efficiency is still not ideal, and the molecular structure design of the material needs to be further optimized; secondly, due to the characteristics of multiple resonance OLED materials, the driving voltage of the OLED device is high; thirdly, the OLED device generates heat during operation, and some multiple resonance OLED materials may have increased molecular thermal motion, crystallization, and other phenomena at high temperatures, which can destroy the ordered structure of the material, affect the carrier transport and luminous efficiency, and shorten the lifespan of the OLED device.

[0006] US2022 / 0077406A1 discloses 、 、 、 The multi-resonance OLED material can reduce the driving voltage and improve the luminous efficiency to a certain extent when the multi-resonance OLED material is used as a guest material in an OLED device, but the service life of the OLED device is still insufficient. SUMMARY

[0007] To solve the problems of the prior art, the present application provides a polycyclic aromatic compound and an electroluminescent device, which solves the problems of the prior art, such as low luminous efficiency, high driving voltage, and insufficient service life of the device.

[0008] The present application is achieved by the following technical solutions:

[0009] In a first aspect, the present application provides a polycyclic aromatic compound, the structure of which is shown in formula (1):

[0010]

[0011] In the formula:

[0012] R1 and R2 are each independently selected from H, cyano, trifluoromethyl, C1-C6 alkyl, and C6-C 12 aryl, and R1 and R2 are each bonded to the main structure by a single bond, and the main structure is ;

[0013] Y is selected from -SiCH3, -SiPh, n-BuGe-, and -P=O;

[0014] X is selected from H and C6-C 20 deuterated aromatic secondary amine;

[0015] A is selected from a carbonyl group and a substituted or unsubstituted C6-C 12 aryl group, B is a substituted or unsubstituted C6-C 12 aryl group, and A and B are not the same; when A is a carbonyl group, “ ” is the carbon atom in the carbonyl group, or “ ” is a single bond, and the 2nd or 3rd position in the main structure is the carbon atom in the carbonyl group; when A is a substituted or unsubstituted C6-C 12 aryl group, “ ” is a chemical bond; B can be referred to as ring B, and A is a substituted or unsubstituted C6-C 12 aryl group, which can be referred to as ring A;

[0016] Z1 and Z2 are each independently selected from 、 , 、 、 、 、 、 、 、 、 and wherein, in Z1, " indicates that Z1 is bonded to the corresponding benzene ring in the main structure at position No. 3 by a single bond, and in Z2, " indicates that Z2 is bonded to the corresponding benzene ring in the main structure at position B by a single bond; Z1 and Z2 are not the same. In the present application, Ph in -SiPh- represents phenyl, and n-Bu in n-BuGe- represents n-butyl.

[0017] In the present application, Ph in -SiPh- represents phenyl, and n-Bu in n-BuGe- represents n-butyl.

[0018] In some preferred embodiments of the present application, Y is selected from -SiCH3, n-BuGe- and -P=O; X is C6~C 20 deuterated aromatic secondary amine.

[0019] In other preferred embodiments of the present application, X is H.

[0020] Preferably, the C1~C6 alkyl group in the present application is selected from methyl and tert-butyl.

[0021] Preferably, the substituted or unsubstituted C6~C 12 aryl group in the present application means that the C6~C 12 aryl group can be further substituted by a substituent, or can not be substituted by a substituent; when the C6~C 12 aryl group is substituted by a substituent, the substituent is selected from methyl, ethyl, propyl and tert-butyl; and the C6~C 12 aryl group is preferably phenyl.

[0022] Preferably, the C6~C 20 deuterated aromatic secondary amine in the present application is selected from and wherein, " indicates the position where X is bonded to the main structure. Preferably, the polycyclic aromatic compound in the present application is selected from one of the following compounds 1~112:

[0023]

[0024] ​​

[0025] In a second aspect, the present application provides an electroluminescent device, comprising a cathode, an anode and an organic layer 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), the hole transport layer is between the anode and the emission material layer, and the electron transport layer is between the cathode and the emission material layer; the components of the emission material layer comprise a host emission material and a guest emission material, and the guest emission material comprises a polycyclic aromatic compound as shown in formula (1).

[0026] Preferably, the guest emission material of the present application is any one of the compounds 1-112 of the present application.

[0027] Preferably, the mass of the guest emission material of the present application accounts for 1-3% of the mass of the emission material layer.

[0028] Preferably, the host material of the present application is selected from , , , and .

[0029] Preferably, a substrate can be further provided outside the anode, and a cover layer can be further provided outside the cathode. The substrate is a glass or polymer material with excellent mechanical strength, thermal stability, water resistance, and transparency, such as ITO conductive glass. In addition, the substrate for display can also have a thin film transistor (TFT) array and a specific display image formed by the array combination.

[0030] Preferably, the anode is usually a substance with a large work function to enable the smooth injection of holes into the organic layer. The anode materials that can be used in the present application include indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), and the like.

[0031] Preferably, the cathode is usually a substance with a small work function to enable the easy injection of electrons into the organic layer. The cathode materials that can be used in the present application 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.

[0032] Preferably, the hole transport layer can be a single-layer hole transport layer containing only one compound (a single-layer hole transport layer 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, which are arranged according to the industry general arrangement mode of hole injection layer (HIL), hole transport layer, and electron blocking layer (EBL). In the present application, the hole injection layer is preferably a p-doped hole injection layer, which means a hole injection layer doped with a p-dopant. The p-dopant is a material that can impart p-type semiconductor properties. The p-type semiconductor properties mean the properties of injecting or transporting holes at the HOMO level, i.e., the properties of high hole conductivity.

[0033] 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 realized by using one or a combination of multiple E1, E2, and E3 with excellent performance in the industry.

[0034] In some embodiments of the present application, the electroluminescent device comprises, in sequence, 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.

[0035] In a third aspect, the present application provides a display panel comprising the electroluminescent device of the present application.

[0036] Compared with the prior art, the present application has the following advantages:

[0037] Firstly, in the structure of the polycyclic aromatic compound of the present application, A and B are not the same, and Z1 and Z2 are not the same, so that the central line of the two six-membered rings in which the heteroatoms Ge, Si or P are located is used as an axis for asymmetric connection. Since the atomic radius of the heteroatoms Ge, Si or P is larger than that of the atom B, the larger Ge, Si or P atoms will cause a certain distortion of the conjugated structure of the molecule. This structural change not only can adjust the frontier orbital distribution of the molecule, and thus control the emission wavelength, but also can promote the molecule to absorb a specific wavelength of light and efficiently convert it into visible light emission, thereby achieving a higher luminescent efficiency. Secondly, the heterocyclic system containing P, Ge or Si atoms and N atoms has a strong electron-withdrawing effect, so that the overlap of the frontier orbitals between the electron donors connected thereto is small, realizing a small energy level difference between the S1 state (excited singlet state) and the T1 state (excited triplet state), thereby realizing reverse intersystem crossing under thermal stimulation, thereby prolonging the luminescent lifetime of the compound and improving the luminescent efficiency. Thirdly, in the structure of the polycyclic aromatic compound of the present application, the benzene ring is bonded to A and B through Z1 and Z2, respectively, and the groups connected by Z1 and Z2 form a stereoisomer 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 makes more excited state energy be released in the form of radiative transition, thereby improving the luminescent efficiency, but also improves the thermal stability of the compound, ensures that the compound still maintains stable structure and luminescent properties at a higher temperature, and prolongs the luminescent lifetime of the compound. Performance tests prove that the polycyclic aromatic compound of the present application applied as a guest luminescent material in the light-emitting layer of an OLED device can effectively reduce the starting voltage of the electroluminescent device, improve the luminescent efficiency, and prolong the service life of the electroluminescent device.

[0038] The electroluminescent device of the present application uses the polycyclic aromatic compound as a guest luminescent material, has a lower starting voltage, a higher luminescent efficiency, and a longer service life. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on these drawings.

[0040] Figure 1 A cross-sectional view of the organic electroluminescent device of the present application;

[0041] Figure 2 NMR spectrum of compound 1 synthesized in Preparation Example 1 of the present application;

[0042] Figure 3 NMR spectrum of compound 2 synthesized in Preparation Example 2 of the present application;

[0043] Figure 4 NMR spectrum of compound 57 synthesized in Preparation Example 4 of the present application;

[0044] Figure 5 NMR spectrum of compound 86 synthesized in Preparation Example 5 of the present application.

[0045] Explanation of reference numerals:

[0046] 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 - capping layer. DETAILED DESCRIPTION

[0047] The present application will be described in more detail by the following specific examples. Other advantages and effects of the present application, which could be easily understood by those skilled in the art from this disclosure, can be easily understood from the present specification. The present application can also be implemented or applied by other different specific embodiments, and each detail in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0048] It should be noted that the process equipment or device not specifically mentioned in the following examples is the conventional equipment or device in the art.

[0049] The synthesis process of compounds 1-112 of the present application is as follows.

[0050] The structures of important reactants L1-L23, X1 and X2 involved in the present application are as follows:

[0051]

[0052] Preparation Example 1 (synthesis of compound 1)

[0053]

[0054] Step one:

[0055] Operation process: under nitrogen protection, 1-bromo-2,6-difluorobenzene (19 g, 0.1 mol), reactant L1 (32 g, 0.1 mol), cesium carbonate (41 g, 0.125 mol), 200 mL DMF were added into a 500 mL three-necked flask, stirring was started, the reaction solution was heated to 130°C, and the reaction was continued for 8 h. After the reaction was completed, the reaction solution was cooled to room temperature, dichloromethane and purified water were added for washing, the organic phase was reserved after the liquid was separated, the aqueous phase was further extracted with dichloromethane, the organic phases were combined, dried with anhydrous magnesium sulfate, concentrated, and purified by silica gel column chromatography (petroleum ether / dichloromethane = 5:1) to obtain compound 1-1, 45 g in weight, 91% in yield, 98% in HPLC (High Performance Liquid Chromatography) purity, and 496.2 in LC-MS (Liquid Chromatograph-Mass Spectrometer) molecular weight.

[0056] Step two:

[0057] Operation process: according to the synthesis process of compound 1-1, 1-bromo-2,6-difluorobenzene was replaced with compound 1-1 (25 g, 0.05 mol), and reactant L1 (32 g, 0.1 mol) was replaced with reactant L3 (16.6 g, 0.05 mol) to obtain compound 1-2, 35 g in weight, 88% in yield, 98% in HPLC purity, and 807.3 in LC-MS molecular weight.

[0058] Step three:

[0059] Procedure: Into a 500 mL three-necked flask, was added a solution of compound 1-2 (16.1 g, 0.02 mol) in 150 mL of tert-butyl benzene under nitrogen protection. The system was cooled to -40 °C and 2.5 M sec-BuLi (9.6 mL, 0.024 mol) in n-hexane was added dropwise. The reaction was warmed to 50 °C and stirred for 1 h. The reaction was stopped and the reaction was concentrated at low temperature to remove the n-hexane. The reaction was cooled to -40 °C again and PhSiCl3 (6.3 g, 0.03 mol) was added. The reaction was transferred to room temperature and stirred for 1 h. Ethyldiisopropylamine (DIEA, EtN(iPr)2) (6.2 g, 0.048 mol) was added dropwise. After the addition was completed, the reaction was slowly warmed to 160 °C and stirred for 18 h until the reaction was complete. The reaction was cooled to room temperature and concentrated. The residue was purified by silica gel column chromatography (petroleum ether / dichloromethane = 3:1) to give compound 1, 9.3 g, 56% yield, 99% HPLC content, LC-MS showed the molecular weight of 829.4. The1H NMR spectrum of compound 1 is shown in Figure 2 .

[0060] 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 = 5.0 Hz, 3H), 7.41 –7.28 (m, 8H), 7.20 (dd, J = 20.7, 15.7 Hz, 5H), 7.07 (t, J = 10.0 Hz, 3H), 7.00(s, 1H), 6.94 (d, J = 5.0 Hz, 4H), 1.69 (s, 6H), 1.30 (d, J = 20.0 Hz, 18H).

[0061] Preparation Example 2 (synthesis of compound 2)

[0062]

[0063] Step one:

[0064] Procedure: Refer to the procedure for the synthesis of compound 1-2 to compound 1, 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, 36 g in weight, 89% yield, 98% HPLC purity, LC-MS shows the molecular weight of 807.3.

[0065] Step two:

[0066] Procedure: Refer to the procedure for the synthesis of compound 2-1 to compound 2, replace the compound 1-2 (16.1 g, 0.02 mol) with the compound 2-1 (16.2 g, 0.02 mol), replace the trichlorophenylsilane (6.3 g, 0.03 mol) with the trichloromethylsilane (4.5 g, 0.03 mol) to obtain compound 2, 8.9 g in weight, 58% yield, 99% HPLC purity, LC-MS shows the molecular weight of 769.4. The NMR spectrum of compound 2 is shown in Figure 3

[0067] 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).

[0068] Preparation 3 (synthesis of compound 39)

[0069]

[0070] Procedure: Refer to the procedure for the synthesis of compound 1-2 to compound 1, replace the trichlorophenylsilane (6.3 g, 0.03 mol) with the trichlorobutylgermane (7.1 g, 0.03 mol) to obtain compound 39, 9.7 g in weight, 57% yield, 99% HPLC purity, LC-MS shows the molecular weight of 855.4.

[0071] Preparation 4 (synthesis of compound 57)

[0072]

[0073] Step one:

[0074] ​Procedure: Refer to the synthesis procedure of compound 1-1, replace the reactant L1 (32 g, 0.1 mol) with reactant L2 (45 g, 0.2 mol), to obtain compound 57-1, 35 g, 89% yield, 98% HPLC purity, LC-MS shows the molecular weight of 400.0.

[0075] Step two:

[0076] Procedure: Refer to the synthesis procedure 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, 31 g, 86% yield, 98% HPLC purity, LC-MS shows the molecular weight of 711.2.

[0077] Step three:

[0078] Procedure: Under nitrogen protection, a 1000 mL three-necked flask was charged with a toluene solution containing compound 57-2 (35 g, 0.05 mol) 400 mL, stirring was started, the system was cooled to -40℃, 1.6M sec-butyllithium (38 mL, 0.05 mol) in n-hexane was added dropwise, the reaction solution was slowly warmed to 50℃ and heated and stirred for 2 hours. The reaction solution was cooled to -10℃, and phosphorus trichloride (PCl3) (16 mL, 0.075 mol) was added dropwise. After the addition was completed, the reaction solution was warmed to 80℃ and reacted for 1h, 3.5g of sulfur (S8) was added, and the reaction was continued for 1h. The reaction solution was cooled to -40℃ again, AlCl3 (81 g, 0.25 mol) and DIEA (23 g, 0.18 mol) were added, and the reaction solution was warmed to 110℃, and the reaction was continued for 12h until the reaction was complete. The reaction solution was cooled to room temperature and concentrated, and the residue was purified by silica gel column chromatography (methyl petroleum ether / dichloromethane = 2:1) to obtain compound 57-3, 19 g, 56% yield, 98% HPLC purity, LC-MS shows the molecular weight of 691.2.

[0079] Step four:

[0080] Operation process: Under nitrogen protection, compound 57-3 (13.8 g, 0.02 mol) and 100 mL of dichloromethane were added to a 250 mL three-necked flask, stirring was started, the system was cooled to -15 ° C, and m-CPBA (m-chloroperbenzoic acid, m-Chloroperbenzoic Acid) (5.5 g, 0.032 mol) was slowly added. The reaction was allowed to react for 1 hour until the reaction was complete. The reaction solution was transferred to room temperature, saturated sodium sulfite aqueous solution (10.0 mL) was added, stirred for 1 hour, insoluble matter was removed, and the liquids were separated. The solvent was removed by distillation under reduced pressure, and the residue was purified by silica gel column chromatography (petroleum ether / dichloromethane = 2:1) to obtain compound 57, weighing 8.2 g, with a yield of 61%, HPLC purity of 99%, and LC-MS showing a molecular weight of 675.2. The nuclear magnetic spectrum of compound 57 is shown as follows Figure 4 shown.

[0081] H NMR spectrum 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).

[0082] Preparation Example 5 (Synthesis of Compound 86)

[0083]

[0084] Step 1:

[0085] Operation process: Under nitrogen protection, 2,5-dibromo-1,3-difluorobenzene (82 g, 0.3 mol), reactant X1 (53 g, 0.3 mol) and 1000 mL of toluene were added to a 2000 mL three-necked flask and stirred until the solution was clear. Pd2(dba)3 (5.5 g, 6 mmol), Am-phos ([(4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine) (4.0 g, 15 mmol), sodium tert-butoxide (58 g, 0.6 mol), the reaction solution was heated to 120°C and the reaction was continued for 10 h. After the reaction was completed, it was filtered through diatomaceous earth while hot, the filtrate was cooled to room temperature, and purified water was added for washing. After separation, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous magnesium sulfate, concentrated, and purified 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 a molecular weight of 366.0 according to LC-MS.

[0086] Step two:

[0087] Procedure: Refer to the synthesis procedure of compound 1-1, replace compound 1-1 (25 g, 0.05 mol) with compound 86-1 (37 g, 0.1 mol), to get compound 86-2, 61 g, 91% yield, 98% HPLC purity, LC-MS shows the molecular weight of 667.3.

[0088] Step three:

[0089] Procedure: Refer to the synthesis procedure of compound 1-1, replace compound 1-1 (25 g, 0.05 mol) with compound 86-2 (33 g, 0.05 mol), to get compound 86-3, 44 g, 89% yield, 98% HPLC purity, LC-MS shows the molecular weight of 978.4.

[0090] Step four:

[0091] Procedure: Refer to the synthesis procedure of compound 57-2 to compound 57-3, replace compound 57-2 (35 g, 0.05 mol) with compound 86-3 (19.6 g, 0.02 mol), to get compound 86-4, 11.9 g, 62% yield, 98% HPLC purity, LC-MS shows the molecular weight of 960.4.

[0092] Step five:

[0093] Procedure: Refer to the synthesis procedure 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 get compound 86, 11.7 g, 62% yield, 99% HPLC purity, LC-MS shows the molecular weight of 944.5. The NMR spectrum of compound 86 is shown in Figure 5

[0094] NMR spectrum 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).

[0095] The synthesis of other compounds can be carried out according to the procedure of Preparation Examples 1-5, using the corresponding reactants L1-L33, X1and X2.

[0096] The compositions and mass spectrometry data of some of the compounds are shown in Table 1:

[0097]

[0098] Based on the above polycyclic aromatic compounds (Compounds 1-112), electroluminescent devices were prepared as guest light-emitting materials. The structure of the electroluminescent device is shown in Figure 1 The preparation method of the electroluminescent device uses the currently recognized device preparation process technology in the industry. The electroluminescent device includes 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.

[0099] Comparative Examples 1-4

[0100] The electroluminescent device was prepared according to the following steps:

[0101] Under high vacuum conditions, on a cleaned conductive glass (as substrate 1), indium tin oxide with a thickness of 25 nm was evaporated as anode 2, a mixture of 10 nm of HT-1 and P-1 (used as a p-dopant, mass ratio 97:3) was evaporated as a hole injection layer 3, 50 nm of HT-1 was evaporated as a hole transport layer 4, 10 nm of EB-1 was evaporated as an electron blocking layer 5, after the electron blocking layer was evaporated, a light-emitting layer 6 with a thickness of 30 nm was prepared, the light-emitting layer 6 used PH-4 as the host light-emitting material, and one of BD0X (Comparative Example 1), BD01 (Comparative Example 2), BD02 (Comparative Example 3), or BD03 (Comparative Example 4) as the guest light-emitting material, and the mass ratio of the host light-emitting material and the guest light-emitting material was 98:2. On the light-emitting layer, 16 nm of HB-1 was evaporated as a hole blocking layer 7. On the hole blocking layer, E1 was evaporated, the vacuum evaporation film thickness of this material was 25 nm, as an electron transport layer 8. On the electron transport layer, a 10 nm layer of LiQ (8-hydroxyquinolinol lithium) was prepared by a vacuum evaporation device, the LiQ layer was an electron injection layer 9. On the electron injection layer, an electrode layer of Al with a thickness of 50 nm was prepared by a vacuum evaporation device, this layer was a cathode 10, and finally a cover layer material X was evaporated to complete the preparation process of the electroluminescent device. The electroluminescent device shown in Figure 1 was prepared by this method.

[0102] The detailed preparation scheme of the electroluminescent device of Comparative Examples 1 to 4 is as follows:

[0103] 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);

[0104] 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);

[0105] 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);

[0106] 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).

[0107] Examples 1 to 3

[0108] The preparation method of Comparative Example 1 is followed, except that the guest light-emitting material BD0X is replaced by the compound 1 of the present application, and the mass ratio of the host light-emitting material and the guest light-emitting material is 97:3 (Example 1), 99:1 (Example 2), and 98:2 (Example 3), respectively.

[0109] The detailed preparation scheme of the electroluminescent device of Examples 1 to 3 is as follows:

[0110] 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);

[0111] Example 2: InSnOx (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);

[0112] Example 3: InSnOx (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).

[0113] Examples 4-33

[0114] According to the preparation method of Comparative Example 1, except that the guest light-emitting material BD0X is replaced by the preferred compound of the present application in turn, the mass ratio of the host light-emitting material and the guest light-emitting material is 98:2, and the specific replacement compound names are shown in Table 2 below.

[0115]

[0116] Part of the materials used in the preparation process of the above electroluminescent device are as follows:

[0117]

[0118] The electroluminescent devices prepared according to the above comparative examples and the examples of the present application were subjected to device display performance data collection, and the collected data are shown in Table 3 below.

[0119]

[0120] As can be seen from the data in Table 3, compared with Pro.1~Pro.4 using BD0X, BD01, BD02, BD03 as guest light-emitting material, the driving voltage of the electroluminescent device in Ex.1~Ex.33 using the polycyclic aromatic compound of the application as guest light-emitting material is reduced, the service life is obviously prolonged, and the current efficiency is improved. It is shown that replacing B with heteroatom Ge, Si or P and forming an asymmetric structure with the middle line of the two six-membered rings where Ge, Si or P is located as the axis can improve the light-emitting efficiency of the OLED device when the polycyclic aromatic compound is used as guest light-emitting material and prolong the service life.

[0121] Compared with Pro.1~Pro.4 using BD0X (green light), BD01~BD03 (blue light) as guest light-emitting material, the emission wavelength of the compounds in Ex.1~Ex.27, Ex.29~Ex.30, Ex.32~Ex.33 using the polycyclic aromatic compound of the application as guest light-emitting material is in the range of blue light~violet light, and the wavelength is obviously blue-shifted.

[0122] Compared with Ex.1~Ex.27, Ex.29~Ex.30, Ex.32~Ex.33, the emission wavelength of the compounds in Ex.28, Ex.31 is obviously red-shifted, which may be due to the fact that the corresponding compound 61 and compound 101 in Ex.28, Ex.31 contain carbonyl group. The double bond (C=O) in the carbonyl group contains 1 σ bond and 1 π bond, and the π electron is in the antibonding orbital (π*). When the carbonyl group is connected with other conjugated systems (such as double bond, benzene ring), a larger conjugated π electron system is formed, so the wavelength is red-shifted.

[0123] Compared with Ex.1~Ex.28, the comprehensive light-emitting performance of the electroluminescent device in Ex.29~Ex.33 has obvious advantages, which may be due to the fact that the substituent X1 in the polycyclic aromatic compound used in Ex.29~Ex.33 is deuterated aromatic secondary amine. After introducing deuterium atom into the compound molecule, the spin-orbital coupling effect of the compound molecule is enhanced, which will increase the intersystem crossing (ISC) ability of the electron in the compound molecule, improve the radiation transition rate of the compound molecule, and reduce the non-radiation transition rate, thereby being conducive to improving the quantum efficiency of the guest light-emitting material, and further improving the comprehensive light-emitting performance of the electroluminescent device.

[0124] As can be seen from the data of the electroluminescent device in Ex.1~Ex.3, when the mass ratio of the guest light-emitting material in the light-emitting layer is in the range of 1%~3%, the comprehensive light-emitting efficiency of the electroluminescent device is similar, and when the mass ratio of the guest light-emitting material is 2%, the light-emitting performance of the prepared electroluminescent device is slightly better than that of Example 1 and Example 2.

[0125] In summary, the polycyclic aromatic compound as a guest light-emitting material applied to the light-emitting layer of the OLED device can effectively reduce the starting voltage of the OLED device and improve the light-emitting efficiency and service life of the OLED device.

[0126] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

[0127] Many other changes and modifications can be made to the application without departing from the spirit and scope of the application. It must be understood that the application is not limited to a particular embodiment, and the scope of the application is defined by the appended claims.

Claims

1. A polycyclic aromatic compound, characterized by, The structural formula of the polycyclic aromatic compound is shown as formula (1): In the formula: R1and R2are each independently selected from the group consisting of H, cyano, trifluoromethyl, C1-C6alkyl, and C6-C10aryl, the bonding of R1and R2to the main structure is each single bond bonding, the main structure is 12 ; and ; and Y is selected from -SiCH3, -SiPh, n-BuGe-, and -P=O; X is C6~C 20 Deuterated aromatic secondary amines; A is selected from carbonyl and substituted or unsubstituted C6~C 12 B is a substituted or unsubstituted C6~C 12 The aromatic group, A and B are different; when the C6~C 12 When the aryl group is substituted by a substituent, the substituent is selected from methyl, ethyl, propyl and tert-butyl; when A is a carbonyl group, " " is a carbon atom in a carbonyl group, or," " is a single bond, and the 2nd or 3rd position in the main structure is the carbon atom in the carbonyl group; when A is a substituted or unsubstituted C6~C 12 When the aromatic group ” is a chemical bond; Z1 and Z2 are each independently selected from 、 、 、 、 、 、 、 、 、 、 and , among which, in Z1" " indicates that Z1 is bonded to the corresponding benzene ring and position 3 in the main structure in the form of a single bond, and Z2" " indicates that Z2 is bonded to the corresponding benzene ring and B in the main structure in the form of a single bond; Z1 and Z2 are different.

2. The polycyclic aromatic compound according to claim 1, characterized by Y is selected from -SiCH3, n-BuGe-, and -P=O.

3. The polycyclic aromatic compound according to claim 2, wherein said deuterated secondary aromatic amine is selected from and wherein, " indicates the position of the bond of X to the host structure.

4. The polycyclic aromatic compound according to claim 1, wherein said deuterated secondary aromatic amine is selected from and wherein, " indicates the position of the bond of X to the main structure.

5. The polycyclic aromatic compound according to claim 1, wherein The C1-C6 alkyl group is selected from methyl and tert-butyl.

6. The polycyclic aromatic compound according to claim 1, wherein The polycyclic aromatic compound is selected from one of the following compounds:

7. An electroluminescent device, characterized by The organic layer comprises 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 comprise a host light-emitting material and a guest light-emitting material, and the guest light-emitting material comprises the polycyclic aromatic compound according to any one of claims 1-6.

8. The electroluminescent device according to claim 7, characterized in that The mass of the guest light-emitting material accounts for 1%-3% of the mass of the light-emitting layer.

9. The electroluminescent device according to claim 7, wherein The host emitter material is selected from , , , and .

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