Organic small molecule material based on xanthene as well as preparation method and electroluminescent application of organic small molecule material

Abstract

The invention belongs to the technical field of organic photoelectric semiconductor materials, and discloses a xanthene-based small organic molecule material as well as a preparation method and application thereof. According to the xanthene-based organic small molecule material structure, triphenylamine is used as a core, a large-volume xanthene spirofluorene unit, a dibenzofuran unit and a carbazole unit are introduced, and the molecular size is increased while the excellent hole mobility of the triphenylamine core is preserved, so that excitons close to an active aromatic amine core are eliminated; the micromolecule has the effect of limiting electron leakage, can keep stable under the action of electrons and excitons, is beneficial to hole injection and transmission, and has the following structural general formula. The xanthene-based small organic molecule material can effectively improve the luminous efficiency and prolong the service life of an organic electroluminescent device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic optoelectronic semiconductor materials, and particularly relates to a kind of organic small molecule materials based on xanthene and a preparation method and electroluminescent application thereof. BACKGROUND

[0002] In recent years, as a new advanced display and lighting solution, organic light-emitting diode (OLED) has attracted extensive attention from academia and industry, and has achieved rapid development under the joint efforts, which has a profound impact on traditional technology system. Currently, OLED is widely used in display modules of smart phones and other electronic devices and various lighting panels. Compared with traditional liquid crystal display (LCD), one of the biggest advantages is the self-luminescent property. LCD relies on backlight illumination, while OLED can directly emit light, thus having lower energy consumption and lighter structure advantages. In addition, OLED can present real pure black when not emitting light, thus realizing higher contrast and wider color gamut. Moreover, OLED does not need backlight module and liquid crystal layer, and can be bent and folded to a large extent, which brings a broad space for innovative design of display devices. Currently, the performance of green OLED and red OLED has basically met the commercialization demand, and has high efficiency and long service life. However, blue OLED still faces the challenge of performance optimization, and its efficiency and stability still need to be further improved to meet the development demand of high-end display technology.

[0003] OLED devices will produce 25% singlet excitons and 75% triplet excitons under current drive. Among them, the singlet exciton has a fast radiative transition rate because the electron spin direction is opposite to that of the ground state, while the radiation of triplet state back to the ground state is spin forbidden. Accumulation of a large number of triplet excitons will cause energy transfer or exciton quenching phenomenon, resulting in dissociation of materials and reduction of exciton utilization rate. In recent years, in order to effectively improve the utilization rate of triplet excitons, fluorescence emission mechanisms such as triplet-triplet annihilation (TTA), triplet-triplet upconversion (TTU) and thermally activated delayed fluorescence (TADF) are used in blue OLED devices. Fluorescent materials usually have better electron transport properties, and electrons are not consumed during the emission process but leaked to the hole transport side, causing bond dissociation of the hole transport material, which reduces the efficiency and service life of the device. Therefore, an electron blocking layer needs to be added to the blue OLED device to optimize and improve the performance of the device.

[0004] Currently, there is limited research on electron blocking materials. Electron blocking materials used in high-performance blue OLED devices typically need to meet the following requirements: (1) Suitable hole mobility, which can effectively reduce the impedance on the hole transport side and enhance hole transport and injection; (2) Electron blocking materials need to have shallow LUMO energy levels to confine electrons in the emissive layer to reduce electron leakage, and have HOMO energy levels that match the hole transport layer and the emissive layer to meet the formation of hole transport channels; (3) High triplet energy, which can prevent energy transfer of triplet excitons and improve exciton utilization; (4) Good thermal stability, which keeps the film stable under the heat of device operation and extends the device lifespan; (5) Good compatibility, which prevents the formation of low-energy charge transfer (CT) states due to intermolecular interactions with the host or dopant. Summary of the Invention

[0005] To improve the luminous efficiency and lifespan of blue OLEDs, this invention aims to provide a novel class of oxanthracene-based organic small molecule materials. The oxanthracene-based organic small molecule materials of this invention are based on a triphenylamine core, an oxanthracene spirofluorene group, a dibenzofuran group, and a carbazole group, with structural modifications achieved by introducing different aromatic ring groups, aromatic heterocyclic groups, or aromatic derivative groups. The introduction of a bulky oxanthracene spirofluorene group significantly improves the material's thermal stability and provides certain electron-donating properties, which is beneficial for increasing the material's LUMO energy level. The dibenzofuran group effectively reduces bond dissociation under electronic influence. The carbazole group enhances hole transport, endowing the material with high HOMO and LUMO energy levels. This type of electron-blocking material exhibits excellent stability and high hole mobility, effectively preventing electron leakage, reducing the hole injection barrier, and improving the photoelectric performance of OLED devices.

[0006] Another objective of this invention is to provide a method for preparing the above-mentioned oxanthracene-based organic small molecule materials.

[0007] Another objective of this invention is to provide the application of the above-mentioned oxanthracene-based organic small molecule material as an electron blocking layer in blue OLEDs.

[0008] This invention is achieved through the following technical solution:

[0009] A class of small organic molecule materials based on oxanthracene has the following structural formula:

[0010]

[0011] Ar1 is an aromatic ring group, an aromatic heterocyclic group, or an aromatic derivative group, and Ar2 is a dibenzofuran group or a carbazole group.

[0012] As a preferred solution, the chemical structure of the organic small molecule material based on xanthene satisfies one of the following structures:

[0013]

[0014]

[0015] The preparation method of the organic small molecule material based on xanthene comprises the following steps:

[0016] (1) Under the atmosphere of inert gas, the Buchwald-Hartwig reaction of compound 4-Ar2-aniline and 1-bromo-4-Ar1-benzene is carried out in an organic solvent under the action of a catalytic system, and after purification, an intermediate product is obtained;

[0017]

[0018] (2) Under the atmosphere of inert gas, the Buchwald-Hartwig reaction of the intermediate product and compound 2'-bromospiro[fluorene-9,9'-xanthene] is carried out in an organic solvent under the action of a catalytic system, and after purification, the final product is obtained.

[0019]

[0020] Preferably, the organic solvent in steps (1) and (2) is at least one of toluene, 1,4-dioxane and tetrahydrofuran, and the amount of the solvent satisfies complete dissolution of the reactants; the catalytic system in steps (1) and (2) independently comprises a base and a catalyst.

[0021] Further preferably, the molar ratio of the compound 4-Ar2-aniline, 1-bromo-4-Ar1-benzene, base and catalyst in step (1) is 1:(1.1-1.3):(3-5):(0.01-0.3); the base is at least one of potassium carbonate, cesium carbonate and sodium tert-butoxide, and more preferably sodium tert-butoxide; the catalyst is at least one of tetrakis triphenylphosphine palladium and palladium acetate, and more preferably tetrakis triphenylphosphine palladium; the reaction temperature is 25-50℃, and the reaction time is 12-24h.

[0022] Further preferably, the catalytic system in step (2) further comprises a ligand, and the molar ratio of the intermediate product, the compound 2'-bromospiro[fluorene-9,9'-xanthene], the base, the catalyst and the ligand in step (2) is 1:(2-5):(3-10):(0.03-0.45):(0.06-0.9); the base is at least one of potassium carbonate, cesium carbonate and sodium tert-butoxide, more preferably sodium tert-butoxide; the catalyst is at least one of tetrakis triphenylphosphine palladium, tris(dibenzylideneacetone)dipalladium and palladium acetate, more preferably tris(dibenzylideneacetone)dipalladium; the ligand is tri-tert-butylphosphine; the reaction temperature is 90-150°C, and the reaction time is 4-12h.

[0023] Preferably, the purification process in step (1) is that after the reaction solution is cooled back to room temperature, dichloromethane and deionized water are used for extraction, the crude product is dissolved in dichloromethane, column chromatography analysis is performed, and the product is concentrated, dried and obtained.

[0024] Preferably, the purification process in step (2) is that after the reaction solution is cooled back to room temperature, dichloromethane and deionized water are used for extraction, the crude product is dissolved in dichloromethane, the mixture of methanol and dichloromethane is used for sedimentation, suction filtration is performed, and the product is dried and obtained.

[0025] The xanthene-based organic small molecule material of the present application is applied to the preparation of an organic electroluminescent device, as an electron blocking material, a hole transport layer or a hole injection layer doped with a P-type dopant.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] (1) The xanthene-based organic small molecule material of the present application has a simple preparation method, easy purification and large-scale production.

[0028] (2) The xanthene-based organic small molecule material of the present application has good stability, good film-forming property, high triplet energy, can prevent electron leakage and can improve the service life of the device.

[0029] (3) The xanthene-based organic small molecule material of the present application is beneficial to hole transport and injection, promotes the process of electron and hole recombination, can reduce the turn-on voltage of the device and improve the photoelectric efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The figure is a nuclear magnetic resonance chart of material C1.

[0031] Figure 2 The figure is a thermogravimetric analysis chart of material C2.

[0032] Figure 3 The figure is a fluorescence emission spectrum chart of material D1 in toluene solution.

[0033] Figure 4 UV-Vis absorption spectrum of material D1 in toluene solution. DETAILED DESCRIPTION

[0034] The application will be described in further detail below with reference to specific embodiments and drawings, but the embodiments of the application are not limited thereto.

[0035] Example 1

[0036] This example provides a preparation of an oxanthrene-based small organic molecule material C1, whose molecular formula is C 55 H 35 NO2, and the specific structure is as follows:

[0037]

[0038] The specific synthesis route and steps are as follows:

[0039]

[0040] (1) Synthesis of compound 1

[0041] A 250 ml round-bottom flask was charged with 4-(4-dibenzofuranyl) aniline (2.59 g, 10 mmol), 4-bromobiphenyl (2.56 g, 11 mmol), sodium tert-butoxide (2.88 g, 30 mmol), palladium acetate (0.22 g, 1 mmol) and toluene (30 ml), and the flask was purged with nitrogen three times. The reaction was stirred with a magnetic stirrer at 25°C for 12 hours. After the reaction was completed, the reaction solution was poured into an aqueous solution, and dichloromethane was used for extraction several times. After the extraction was completed, the organic liquid layer was dried with anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. Purification was performed by silica gel column chromatography, eluent was dichloromethane and petroleum ether, and then recrystallization was performed in n-hexane and chloroform to obtain a white powder. 1 HNMR、 13 CNMR, MS and elemental analysis results show that the obtained compound is the target product. Among them 1 H NMR (500 MHz, DMSO-d6) δ 8.19-8.13 (m, 1H), 8.06 (d, J = 9.2 Hz, 1H), 7.94 (dd, J = 9.2, 0.7 Hz, 1H), 7.80 (dd, J = 6.8, 1.5 Hz, 1H), 7.69 (dd, J = 8.1, 1.4 Hz, 2H), 7.61-7.34 (m, 10H), 7.15 (t, J = 8.0 Hz, 4H), 6.82 (s, 1H).

[0042] (2) Synthesis of compound C1

[0043] Compound 1 (2.06 g, 5 mmol), 2'-bromospiro[fluorene-9,9'-xanthene] (6.17 g, 15 mmol), sodium tert-butoxide (1.44 g, 15 mmol), tris(dibenzylideneacetone)dipalladium (0.92 g, 1 mmol), tri-tert-butylphosphine (0.4 g, 2 mmol) and toluene (20 ml) were placed in a 250 ml round bottom flask, purged with nitrogen three times, heated to 100°C to generate reflux, and stirred with a magnetic bar under reflux conditions for 5 hours. After the reaction was completed, the reaction solution was poured into an aqueous solution, and extracted with dichloromethane several times. After the extraction was completed, the organic liquid layer was dried with anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by sedimentation with methanol and dichloromethane, filtered and dried, and then recrystallized in n-hexane and chloroform to obtain a white solid. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product. Among them 1 H NMR (500 MHz, DMSO-d6) δ 8.19-8.13 (m, 1H), 8.06 (d, J = 9.2 Hz, 1H), 7.94 (dd, J = 9.2, 0.7 Hz, 1H), 7.86 (dd, J = 6.7, 1.3 Hz, 2H), 7.80 (dd, J = 6.8, 1.5 Hz, 1H), 7.69 (dd, J = 8.1, 1.4 Hz, 2H), 7.61-7.34 (m, 17H), 7.24-7.10 (m, 7H), 7.08-6.99 (m, 2H), 6.82 (s, 1H).

[0044] Example 2

[0045] This example provides a preparation of an organic small molecule material C2 based on xanthene, whose molecular formula is C 64 H 43 NO2, and the specific structure is as follows:

[0046]

[0047] The specific synthesis route and steps are as follows:

[0048]

[0049] (1) Synthesis of compound 2

[0050] A 250 ml round bottom flask was charged with 4-(4-dibenzofuranyl) aniline (2.59 g, 10 mmol), 1-(4-bromobiphenyl)-9,9-dimethyl-9H-fluorene (4.54 g, 13 mmol), sodium tert-butoxide (2.88 g, 30 mmol), palladium acetate (0.22 g, 1 mmol) and toluene (30 ml), and the flask was purged with nitrogen three times. The reaction was heated to 50°C and stirred with a magnetic stirrer for 24 hours. After the reaction was completed, the reaction solution was poured into an aqueous solution, and extracted several times with dichloromethane. After the extraction was completed, the organic layer was dried with anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography using dichloromethane and petroleum ether as eluents, and then recrystallized from n-hexane and chloroform to obtain a light yellow powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product. Among them 1 H NMR (500 MHz, DMSO-d6) δ 8.19-8.13 (m, 1H), 8.06 (d, J = 9.1 Hz, 1H), 7.94 (dd, J = 9.2, 0.7 Hz, 1H), 7.86-7.77 (m, 2H), 7.64-7.51 (m, 6H), 7.50-7.31 (m, 7H), 7.14 (dd, J = 8.1, 6.7 Hz, 4H), 6.81 (s, 1H), 1.59 (s, 6H).

[0051] (2) Synthesis of compound C2

[0052] A 250 ml round bottom flask was charged with compound 2 (2.64 g, 5 mmol), 2'-bromospiro[fluorene-9,9'-xanthene] (6.17 g, 15 mmol), sodium tert-butoxide (1.44 g, 15 mmol), tris(dibenzylideneacetone)dipalladium (0.92 g, 1 mmol), tri-tert-butylphosphine (0.4 g, 2 mmol) and toluene (20 ml), and the flask was purged with nitrogen three times. The reaction was heated to 120°C to produce reflux, and stirred with a magnetic stirrer for 6 hours under reflux conditions. After the reaction was completed, the reaction solution was poured into an aqueous solution, and extracted several times with dichloromethane. After the extraction was completed, the organic layer was dried with anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by precipitation with methanol and dichloromethane, filtered and dried, and then recrystallized from n-hexane and chloroform to obtain a yellow solid. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product. Among them 1H NMR (500 MHz, DMSO-d6) δ 8.19 - 8.13 (m, 1H), 8.06 (d, J = 9.2 Hz, 1H), 7.94 (dd, J = 9.2, 0.7 Hz, 1H), 7.88 - 7.84 (m, 3H), 7.80 (dd, J = 6.8, 1.5 Hz, 1H), 7.62 - 7.52 (m, 6H), 7.52 - 7.29 (m, 14H), 7.25 - 7.11 (m, 5H), 7.10 - 7.04 (m, 3H), 7.01 (dd, J = 6.9, 1.2 Hz, 1H), 6.95 (d, J = 7.5 Hz, 1H), 1.59 (s, 6H).

[0053] Example 3

[0054] This example provides a preparation of an organic small molecule material D1 based on xanthene, whose molecular formula is C 61 H 37 NO3, and the specific structure is as follows:

[0055]

[0056] The specific synthesis route and steps are as follows:

[0057]

[0058] (1) Synthesis of compound 3

[0059] A 250 ml round bottom flask was charged with 4-(4-dibenzofuranyl) aniline (2.59 g, 10 mmol), 4-(4-bromophenyl)-dibenzofuran (3.88 g, 12 mmol), sodium tert-butoxide (2.88 g, 30 mmol), palladium acetate (0.22 g, 1 mmol) and toluene (30 ml), and then purged with nitrogen three times, heated to 40°C, and stirred with a magnetic stirrer for 24 hours. After the reaction was completed, the reaction solution was poured into an aqueous solution, and extracted several times with dichloromethane. After extraction, the organic layer was dried with anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. Purification was performed by silica gel column chromatography, eluted with dichloromethane and petroleum ether, and then recrystallized in n-hexane and chloroform to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results show that the obtained compound is the target product. Among them 1H NMR(500MHz,DMSO-d6)δ8.19-8.13(m,2H),8.06(dd,J=9.3,0.8Hz,2H),7.94(dd,J=9.2,0.7Hz,2H) ,7.80(dd,J=6.8,1.4Hz,2H),7.57-7.51(m,4H),7.50-7.34(m,6H),7.17-7.11(m,4H),6.81(s,1H).

[0060] (2) Synthesis of compound D1

[0061] Compound 3 (2.51 g, 5 mmol), 2'-bromospiro[fluorene-9,9'-oxazanthene] (6.17 g, 15 mmol), sodium tert-butoxide (1.44 g, 15 mmol), tris(dibenzylacetone)dipalladium (0.92 g, 1 mmol), tri-tert-butylphosphine (0.4 g, 2 mmol), and toluene (20 ml) were placed in a 250 ml round-bottom flask, purged with nitrogen three times, and heated to 120 °C under reflux. The mixture was stirred magnetically for 8 hours under reflux. After the reaction was complete, the reaction solution was poured into an aqueous solution and extracted several times with dichloromethane. After extraction, the organic liquid layer was dried with anhydrous magnesium sulfate and evaporated under reduced pressure to obtain the crude product. The crude product was purified by precipitation with methanol and dichloromethane, filtered, dried, and then recrystallized in n-hexane and trichloromethane to obtain a white solid. 1 HNMR, 13 CNMR, MS, and elemental analysis results indicate that the obtained compound is the target product. 1 H NMR (500MHz, DMSO-d6) δ8.19-8.13(m,2H),8.06(d,J=9.2Hz,2H),7.94(dd,J=9.2,0.7Hz,2H),7.86(dd,J=6.8,1.3Hz,2H),7. 80(dd,J=6.8,1.5Hz,2H),7.59–7.53(m,4H),7.52–7.29(m,13H),7.24–7.10(m,7H),7.08–6.99(m,2H),6.95(d,J=7.5Hz,1H).

[0062] Application Example 1

[0063] This embodiment provides a method for fabricating a blue undoped organic light-emitting diode (OLED) device. The method is as follows: An indium tin oxide (ITO) substrate with a sheet resistance of 15Ω is ultrasonically cleaned in a mixture of acetone, detergent, deionized water, detergent, and isopropanol. The cleaned ITO is then subjected to plasma etching for 3 minutes. The treated ITO is then placed in a vacuum evaporation apparatus until the vacuum level in the evaporation chamber reaches 10... -5 When Pa is below, A 20 nm thick layer of 1,4,5,8,9,11-hexaazabenzophenanthrenehexacarbonitrile (HATCN) was deposited at a specific rate as a hole injection layer. Then, using... A 20 nm thick layer of N,N,N',N'-tetraphenylbenzidine diamine (BPBPA) was deposited at a specific rate as a hole transport layer. Then, using... A 10 nm thick electron blocking layer (C1, C2, D1) pure film was deposited at a rate of [missing information]. Then, [missing information]... A 20 nm thick layer of adiponitrile-9,10-bis(2-naphthyl)anthracene (ADN) was deposited at a specific rate as the luminescent layer. Then, using... A 30 nm thick layer of 2,2',2”-(1,3,5-phenyltriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBI) was deposited at a specific rate as an electron transport layer. Then, using… A 1 nm thick lithium fluoride (LiF) layer was deposited at a high rate as an electron injection layer. Finally, a 1 nm thick lithium fluoride (LiF) layer was deposited. A 90 nm thick ultrapure aluminum cathode (Al) was deposited at a high rate. The device structure was ITO / HATCN / BPBPA / C1 or C2 or D1 / ADN / TPBI / LiF / Al, and a device without an electron blocking layer was fabricated for comparison.

[0064] The fabricated device was cured and encapsulated using epoxy resin and a thin glass layer under ultraviolet light. Under atmospheric conditions, the device was driven by a voltage applied to a Keithley 2450 source meter, and the current density versus voltage characteristics were obtained. Electroluminescence (EL) spectra were obtained using a Photo Research PR745 optical analyzer, and brightness versus driving voltage characteristics were obtained using a Konica Minolta CS-200 colorimeter. The external quantum efficiency, satisfying Lambertian's law, was calculated from the brightness, current density, and EL spectrum. A constant current density of 50 mA / cm² was applied to the Keithley 2450 source meter. 2 The brightness was recorded using a Konica Minolta CS-200 colorimeter, and the lifetime time for the device brightness to decay from the initial value to 95% was obtained.

[0065] The performance parameters of the fabricated undoped OLED devices are shown in Table 1.

[0066] Table 1 Performance parameters of undoped organic electroluminescent devices

[0067]

[0068] Application Example 2

[0069] This embodiment provides a method for fabricating a blue-doped organic light-emitting diode (OLED) device. The method is as follows: An indium tin oxide (ITO) substrate with a sheet resistance of 15Ω is ultrasonically cleaned in a mixture of acetone, detergent, deionized water, detergent, and isopropanol. The cleaned ITO is then subjected to plasma etching for 3 minutes. The treated ITO is then placed in a vacuum evaporation apparatus until the vacuum level in the evaporation chamber reaches 10... -5 When Pa is below, A 20 nm thick layer of 1,4,5,8,9,11-hexaazabenzophenanthrenehexacarbonitrile (HATCN) was deposited at a specific rate as a hole injection layer. Then, using... A 20 nm thick layer of N,N,N'-tetra(4-biphenyl)-4,4'-biphenyldiamine (BPBPA) was deposited at a specific rate as a hole transport layer. Then, using... A 10 nm thick electron blocking layer (C1, C2, D1) pure film was deposited at a rate of [missing information]. Then, [missing information]... rate and Simultaneously, a 20 nm thick layer of adiponitrile-9,10-bis(2-naphthyl)anthracene (ADN) and N1,N6-bis(dibenzo[b,d]furan-4-yl)-3,8-diisopropyl-N1,N6-bis(4-isopropylphenyl)pyrene-1,6-diamine (BDFDPPDA) were deposited as the luminescent layer. Then, using... A 30 nm thick layer of 2,2',2”-(1,3,5-phenyltriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBI) was deposited at a specific rate as an electron transport layer. Then, using… A 1 nm thick lithium fluoride (LiF) layer was deposited at a high rate as an electron injection layer. Finally, a 1 nm thick lithium fluoride (LiF) layer was deposited. A 90 nm thick ultrapure aluminum cathode (Al) was deposited at a high rate. The device structure was ITO / HATCN / BPBPA / C1orC2orD1 / BDFDPPD(5%):ADN / TPBI / LiF / Al, and a device without an electron blocking layer was fabricated for comparison.

[0070] The fabricated device was cured and encapsulated using epoxy resin and a thin glass layer under ultraviolet light. The device was driven by a voltage applied to a Keithley 2450 source meter, and the current density versus voltage characteristics were obtained. Electroluminescence (EL) spectra were obtained using a PhotoResearch PR745 optical analyzer, and luminance versus driving voltage characteristics were obtained using a Konica Minolta CS-200 colorimeter. The external quantum efficiency, satisfying Lambertian's law, was calculated from the luminance, current density, and EL spectrum. A constant current density of 50 mA / cm² was applied to the Keithley 2450 source meter. 2 The brightness was recorded using a Konica Minolta CS-200 colorimeter, and the lifetime time for the device brightness to decay from the initial value to 95% was obtained.

[0071] The performance parameters of the fabricated doped OLED devices are shown in Table 2.

[0072] Table 2 Performance parameters of doped organic light-emitting devices

[0073] Application Example 3

[0074] This embodiment provides a method for fabricating a blue-doped organic light-emitting diode (OLED) device. The method is as follows: An indium tin oxide (ITO) substrate with a sheet resistance of 15Ω is ultrasonically cleaned in a mixture of acetone, detergent, deionized water, detergent, and isopropanol. The cleaned ITO is then subjected to plasma etching for 3 minutes. The treated ITO is then placed in a vacuum evaporation apparatus until the vacuum level in the evaporation chamber reaches 10... -5 When Pa is below, rate and Simultaneously, 30 nm thick C1 / C2 / D1 and 1,4,5,8,9,11-hexaazabenzophenanthrenehexacarbonitrile (HATCN) layers were deposited at the same rate as hole injection layers. Then, using... A 20 nm thick layer of 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC) was deposited at a certain rate as a hole transport layer, and then... A 10 nm thick layer of 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA) was deposited at a specific rate as an electron blocking layer. Then, using... rate and Simultaneously, a 20 nm thick layer of adiponitrile-9,10-bis(2-naphthyl)anthracene (ADN) and N1,N6-bis(dibenzo[b,d]furan-4-yl)-3,8-diisopropyl-N1,N6-bis(4-isopropylphenyl)pyrene-1,6-diamine (BDFDPPDA) were deposited as the luminescent layer. Then, using... A 30 nm thick layer of 2,2',2"-(1,3,5-benzene triyl)-tris(1-phenyl-1-H- benzimidazole) (TPBI) was deposited at a rate of 0.1 A / s as an electron transport layer. Then a 1 nm thick layer of lithium fluoride (LiF) was deposited at a rate of 0.1 A / s as an electron injection layer. Finally, a 90 nm thick layer of ultrapure aluminum cathode (Al) was deposited at a rate of 10 A / s. The device structure was ITO / HATCN(3%):C1 or C2 or D1 / TAPC / TCTA / BDFDPPDA(5%):ADN / TPBI / LiF / Al, and a device without a hole injection layer was prepared for comparison. A 30 nm thick layer of 2,2',2"-(1,3,5-benzene triyl)-tris(1-phenyl-1-H- benzimidazole) (TPBI) was deposited at a rate of 0.1 A / s as an electron transport layer. Then a 1 nm thick layer of lithium fluoride (LiF) was deposited at a rate of 0.1 A / s as an electron injection layer. Finally, a 90 nm thick layer of ultrapure aluminum cathode (Al) was deposited at a rate of 10 A / s. The device structure was ITO / HATCN(3%):C1 or C2 or D1 / TAPC / TCTA / BDFDPPDA(5%):ADN / TPBI / LiF / Al, and a device without a hole injection layer was prepared for comparison. A 30 nm thick layer of 2,2',2"-(1,3,5-benzene triyl)-tris(1-phenyl-1-H- benzimidazole) (TPBI) was deposited at a rate of 0.1 A / s as an electron transport layer. Then a 1 nm thick layer of lithium fluoride (LiF) was deposited at a rate of 0.1 A / s as an electron injection layer. Finally, a 90 nm thick layer of ultrapure aluminum cathode (Al) was deposited at a rate of 10 A / s. The device structure was ITO / HATCN(3%):C1 or C2 or D1 / TAPC / TCTA / BDFDPPDA(5%):ADN / TPBI / LiF / Al, and a device without a hole injection layer was prepared for comparison.

[0075] The prepared devices were encapsulated using epoxy resin and thin layer glass under ultraviolet light irradiation. The devices were driven by a voltage applied by a Keithley 2450 source meter to obtain current density versus voltage characteristics; by a Photo Research PR745 optical analyzer to obtain electroluminescence (EL) spectra; and by a Konica Minolta colorimeter CS-200 to obtain luminance versus driving voltage characteristics. The external quantum efficiency was calculated according to Lambertian law from the luminance, current density, and EL spectrum.

[0076] The performance parameters of the prepared doped OLED devices are shown in Table 3.

[0077] Table 3 Performance parameters of doped organic electroluminescent devices

[0078]

[0079]

[0080] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are within the scope of the present application.

Claims

1. A class of small organic molecule materials based on xanthene, characterized in that, The chemical structural formula satisfies the following general formula: Wherein Ar1 is an aromatic ring group, an aromatic heterocyclic group or an aromatic derivative group, and Ar2 is a dibenzofuran group or a carbazole group.

2. The hetaryum-based organic small-molecule material according to claim 1, characterized in that The chemical structural formula satisfies one of the following structures:

3. The hetaryum-based organic small-molecule material according to claim 1, characterized in that The chemical structural formula satisfies one of the following structures:

4. A method of preparing an organic small-molecule material based on xanthene according to any one of claims 1 to 3, characterized in that The method comprises the following steps: (1) Buchwald-Hartwig reaction of compound 4-Ar2-aniline and 1-bromo-4-Ar1-benzene in an organic solvent under an inert gas atmosphere in the presence of a catalytic system, and purification to obtain an intermediate product; (2) Buchwald-Hartwig reaction of the intermediate product and compound 2'-bromospiro[fluorene-9,9'-xanthene] in an organic solvent under an inert gas atmosphere in the presence of a catalytic system, and purification to obtain the final product.

5. The method for preparing organic small molecule materials based on xanthracene according to claim 4, characterized in that, The organic solvent in steps (1) and (2) is at least one of toluene, 1,4-dioxane and tetrahydrofuran, and the amount of the solvent satisfies complete dissolution of the reactants; the catalytic system in steps (1) and (2) comprises a base and a catalyst.

6. The method for preparing organic small molecule materials based on xanthracene according to claim 4, characterized in that, The molar ratio of the compound 4-Ar2-aniline, 1-bromo-4-Ar1-benzene, base and catalyst in step (1) is 1:(1.1-1.3):(3-5):(0.01-0.3); the base is at least one of potassium carbonate, cesium carbonate and sodium tert-butoxide, and the catalyst is at least one of tetrakis(triphenylphosphine)palladium and palladium acetate; the reaction temperature is 25-50°C, and the reaction time is 12-24h.

7. The method for preparing organic small molecule materials based on oxanthracene according to claim 4, characterized in that, The catalytic system in step (2) further comprises a ligand, and the molar ratio of the intermediate product, compound 2'-bromospiro[fluorene-9,9'-xanthene], base, catalyst and ligand in step (2) is 1:(2-5):(3-10):(0.03-0.45):(0.06-0.9); the base is at least one of potassium carbonate, cesium carbonate and sodium tert-butoxide, the catalyst is at least one of tetrakis(triphenylphosphine)palladium, tris(dibenzylideneacetone)dipalladium and palladium acetate, and the ligand is tri-tert-butylphosphine; the reaction temperature is 90-150°C, and the reaction time is 4-12h.

8. Use of the xanthene-based small organic molecule material according to any one of claims 1-3 as an electron blocking layer in an organic electroluminescent device.

9. Use of the xanthene-based small organic molecule material according to any one of claims 1-3 as an electron blocking layer in a blue organic electroluminescent device.

10. Use of the xanthene-based small organic molecule material according to any one of claims 1-3 as a hole transport layer or a hole injection layer doped with a P-type dopant in an organic electroluminescent device.

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