An organic electroluminescent doping material and a light-emitting device

Abstract

The present invention provides an organic electroluminescent doping material and a light-emitting device. By introducing a deuterium atom group at a specific position on the thiophene ring, the molecular spacing and bond energy of the obtained compound are adjusted, and a doping material with a specific atomic structure is obtained. After using the obtained organic compound with a specific atomic structure in an organic electroluminescent device, the driving voltage is reduced and the light-emitting efficiency of the device is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescent materials. Specifically, it relates to an organic electroluminescent material doping and light-emitting device, and particularly to an organic electroluminescent material and a light-emitting device used as a doping material in organic light-emitting diodes and related electronic devices. Background Art

[0002] Organic semiconductor materials belong to new optoelectronic materials. Their large-scale origin dates back to 1977 when doped polyethylene with a conductivity up to the level of copper was jointly discovered by Hideki Shirakawa, A. Heeger, and A. MacDiarmid. Subsequently, in 1987, C. Tang of Kodak Company et al. invented the organic small molecule light-emitting diode (OLED). When a voltage is applied to a device containing an OLED organic film, light is emitted, and OLEDs have gradually received increasing attention in flat panel displays, lighting, and backlight applications.

[0003] Since 2000, the deuteration strategy has been widely used in the optoelectronic materials industry. The luminescent material of OLED has gradually become a key material affecting the display effect and service life of OLED due to its fast attenuation rate. In the OLED matrix material, the hydrogen / deuterium exchange of the unstable heterocyclic carbon-hydrogen bond can extend the service life of the device. Replacing the unstable C-H bond in the main structure with a C-D bond can increase the device life to about 5 times without loss of efficiency. Therefore, deuterated materials can not only improve the luminescence efficiency and flexible display of OLED devices, but also have characteristics such as increased brightness and long half-life.

[0004] Deuterium is non-toxic and non-radioactive, safe for the human body. More importantly, the C-D bond is more stable than the C-H bond (6 - 9 times). When deuterium atoms are introduced into the material, the spin-orbit coupling effect of the luminescent molecules will be enhanced, which is conducive to the generation of phosphorescence and increases its quantum efficiency. In addition, after introducing deuterium atoms, due to the shorter bond length and larger bond energy of the carbon-deuterium bond, the energy of the luminescent material will decrease, thus significantly enhancing the stability and life of the light-emitting device.

[0005] The literature "Isotope Effect of Host Material on Device Stability of Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes" points out that the green TADF-OLED based on the deuterated compound (PYD2Cz-d16) shows more balanced carrier transport characteristics than the non-deuterated compound (PYD2Cz), thus obtaining better device stability. At an initial brightness of 1000 cd / m 2When the LT95 is 134 h, which is 1.7 times that of the compound (PYD2Cz). It can be seen that deuteration can improve the device lifetime, while the improvement of the driving voltage and device efficiency is unpredictable.

[0006] In the literature "Synthesis of all-deuterated tris(2-phenylpyridine) iridium for highly stable electrophosphorescence: the “deuterium effect”", it is also confirmed that the deuteration of Ir(ppy)3 only slightly improves its photophysical properties, but has a significant impact on the stability and lifetime of the device. At an initial brightness of 1000 cd / m 2 , the device based on Ir(ppy)3-D24 has a 20-fold higher current density and a 6-fold longer lifetime than Ir(ppy)3. Through infrared spectroscopy comparison and DFT calculation, it can be proved that Ir(ppy)3-D24 has much lower internal energy than Ir(ppy)3, especially C-D stretching and bending, which are the main factors for improving device stability and extending device lifetime, and this is called the “deuterium effect”.

[0007] That is to say, at present, it is known that deuterating OLED materials can improve the lifetime of OLED devices, but how to improve the driving voltage and luminous efficiency of the devices is a technical problem that urgently needs to be solved at present. Summary of the Invention

[0008] In view of this, in order to solve the above problems, the present invention provides an organic electroluminescent doping material and a light-emitting device. By introducing a deuterium atom group at a specific position on the thiophene ring, the molecular spacing and bond energy of the obtained compound are adjusted, and a doping material with a specific atomic structure is obtained. After using the obtained organic compound with a specific atomic structure in an organic electroluminescent device, the driving voltage is reduced and the luminous efficiency of the device is improved.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] The present invention provides an organic electroluminescent doping material, which is a compound having the structure shown in Formula I: M(L A )2(L B );

[0011] Wherein, M is a metal;

[0012] L A and L B are both ligands, and L A and L B have the following general formula:

[0013]

[0014] Wherein, Ar1 and Ar2 are independently selected from -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -Ge(Me)3, -Si(Me)3, substituted or unsubstituted C2-C6 alkyl, substituted and unsubstituted C3-C 20 cycloalkyl, substituted or unsubstituted C6-C 10 aryl, and any one of substituted or unsubstituted 4- to 8-membered aromatic heterocyclic groups;

[0015] R1, R2, R3, R4, R5, R6, R7, R8, R9 are independently selected from -H, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -Ge(Me)3, -Si(Me)3, substituted or unsubstituted C2-C6 alkyl, substituted and unsubstituted C3-C 20 cycloalkyl, substituted or unsubstituted C6-C 10 aryl, and any one of substituted or unsubstituted 4- to 8-membered aromatic heterocyclic groups;

[0016] R 10 、R 11 、R 12 are independently selected from -H, -D (deuterium), -T (tritium), -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -Ge(Me)3, -Si(Me)3, substituted or unsubstituted C2-C6 alkyl, substituted and unsubstituted C3-C 20 cycloalkyl, substituted or unsubstituted C6-C 10 aryl, and any one of substituted or unsubstituted 4- to 8-membered aromatic heterocyclic groups.

[0017] According to an embodiment of the present invention, M is preferably the metal Ir.

[0018] According to an embodiment of the present invention, Ar1 and Ar2 are independently selected from -F, -CN, -CF3, -CH2F, -CHF2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, terphenyl, fluorenyl, phenanthryl, triphenylenyl, furyl, benzofuryl, benzothienyl, dibenzofuryl, dibenzothienyl, or any one of the following substituents:

[0019] ;

[0020] It should be noted that in the present invention, * represents the connection position; "substituted" means that it can be substituted by groups such as -H, -D (deuterium), -T (tritium), -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -Ge(Me)3, -Si(Me)3, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, thiolane, phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, phenanthryl, anthryl, indenyl, triphenylenyl, fluoranthenyl, furyl, thienyl, imidazolyl, pyrazolyl, thiazolyl, pyridyl, pyrazinyl, pyrimidinyl, benzofuryl, benzothienyl, isobenzofuryl, dibenzofuryl, dibenzothienyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzothiadiazolyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, carbazolyl, etc.

[0021] According to an embodiment of the present invention, R1-R9 are selected from the following groups: one or more of -H, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -Ge(Me)3, -Si(Me)3, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, thiolane, phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, phenanthryl, anthryl, indenyl, triphenylenyl, fluoranthenyl, furyl, thienyl, imidazolyl, pyrazolyl, thiazolyl, pyridyl, pyrazinyl, pyrimidinyl, benzofuryl, benzothienyl, isobenzofuryl, dibenzofuryl, dibenzothienyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzothiadiazolyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, carbazolyl, etc.

[0022] According to an embodiment of the present invention, R 10 、R 11 、R 12Independently selected from one or more of the following groups: -H, -D (deuterium), -T (tritium), -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -Ge(Me)3, -Si(Me)3, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, tetrahydrofuran, pyrrolidine, thiolane, tetrahydropyran, phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, phenanthryl, anthryl, indenyl, triphenylenyl, pyrenyl, quaterphenyl, perylenyl, chrysenyl, tetrabenaphthenyl, fluoranthenyl, furyl, thienyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, furazanyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, benzofuranyl, benzothienyl, isobenzofuranyl, dibenzofuranyl, dibenzothienyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl, phenoxazinyl, phenanthridinyl, benzodioxolyl, etc.

[0023] According to an embodiment of the present invention, the organic electroluminescent doping material is selected from any one of the following structures:

[0024]

[0025] The present invention also provides a preparation method of an organic electroluminescent doping material. The preparation process of the organic electroluminescent doping material of the compound shown in Formula I is as follows:

[0026]

[0027] Wherein the definitions in the above formula are the same as those described above, and will not be repeated here.

[0028] The present invention also provides an organic electroluminescent device, including a first electrode, a second electrode, and an organic material layer located between the first electrode and the second electrode; the organic material layer can be further divided into multiple regions. For example, the organic material layer includes a hole transport region, a light-emitting layer, and an electron transport region; the light-emitting layer contains an organic electroluminescent doping material.

[0029] According to an embodiment of the present invention, the light-emitting layer may include light-emitting dyes (i.e., dopants) that emit different wavelength spectra, and may also include a host material at the same time. The light-emitting layer may be a monochromatic light-emitting layer that emits a single color such as red, green, or blue. Multiple different-color monochromatic light-emitting layers may be arranged in a planar pattern according to a pixel pattern, or may be stacked together to form a color light-emitting layer. When different-color light-emitting layers are stacked together, they may be separated from each other or connected to each other. The light-emitting layer may also be a single color light-emitting layer that can simultaneously emit different colors such as red and green.

[0030] According to an embodiment of the present invention, the organic electroluminescent doping material may be made of different materials such as phosphorescent electroluminescent materials and thermally activated delayed fluorescence materials. In an OLED device, a single light-emitting technology may be adopted, or a combination of multiple different light-emitting technologies may be adopted. These different light-emitting materials classified by technology may emit light of the same color or different colors. The light-emitting layer may adopt the technology of phosphorescent electroluminescence.

[0031] According to an embodiment of the present invention, the organic electroluminescent device includes an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode that are sequentially arranged.

[0032] According to an embodiment of the present invention, a substrate may be used below the first electrode or above the second electrode. The substrates are all glass or polymer materials with excellent mechanical strength, thermal stability, waterproofness, and transparency. In addition, thin-film transistors (TFTs) may also be provided on the substrate for use as a display.

[0033] According to an embodiment of the present invention, the first electrode may be formed by sputtering or depositing a first electrode material on the substrate. When the first electrode is used as an anode, oxide transparent conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), etc., and any combination thereof may be adopted.

[0034] According to an embodiment of the present invention, the anode material may also be selected from materials that contribute to hole injection and their combinations in addition to the listed anode materials, including known materials suitable for use as an anode.

[0035] According to an embodiment of the present invention, when the first electrode is used as a cathode, metals or alloys such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), etc., and any combination thereof may be adopted.

[0036] In addition to the cathode materials listed above, the cathode material can also be a material that facilitates electron injection and combinations thereof, including known materials suitable for use as cathodes.

[0037] According to an embodiment of the present invention, the organic material layer can be formed on the electrode by methods such as vacuum thermal evaporation, spin coating, printing, etc.

[0038] According to an embodiment of the present invention, the compound used as the organic material layer can be an organic small molecule, an organic macromolecule, a polymer, and combinations thereof.

[0039] According to an embodiment of the present invention, the hole transport region is located between the anode and the light-emitting layer. The hole transport region can be a single-layer hole transport layer (HTL), including a single-layer hole transport layer with only one compound and a single-layer hole transport layer containing multiple compounds.

[0040] According to an embodiment of the present invention, the hole transport region can also be a multi-layer structure including at least one layer of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL).

[0041] According to an embodiment of the present invention, the material of the hole transport layer can be selected from phthalocyanine derivatives, such as CuPc, conductive polymers, etc.

[0042] According to an embodiment of the present invention, the material of the hole transport layer can be selected from polymers containing a conductive dopant.

[0043] For example, poly(phenylene vinylene), polyaniline / dodecylbenzenesulfonic acid (Pani / DBSA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), polyaniline / camphorsulfonic acid (Pani / CSA), polyaniline / poly(4-styrenesulfonate) (Pani / PSS), aromatic amine derivatives such as the compounds shown by HT-1 to HT-34 below; or any combination thereof.

[0044]

[0045] However, it is not limited to the above several materials.

[0046] According to an embodiment of the present invention, the hole injection layer is located between the anode and the hole transport layer.

[0047] According to an embodiment of the present invention, the hole injection layer can be a single compound material or a combination of multiple compounds.

[0048] For example, the hole injection layer can be selected from one or more compounds of HT-1 to HT-34 described above, or one or more compounds of HI-1 to HI-3 described below; it can also be one or more compounds of HT-1 to HT-34 doped with one or more compounds of HI-1 to HI-3:

[0049]

[0050] However, it is not limited to the above several materials.

[0051] The OLED organic material layer may further include an electron transport region between the light emitting layer and the cathode. The electron transport region can be a single-layer electron transport layer (ETL) structure, including a single-layer electron transport layer containing only one compound and a single-layer electron transport layer containing multiple compounds. The electron transport region can also be a multi-layer structure including at least one of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL).

[0052] In one aspect of the present invention, the electron transport layer material can be selected from, but not limited to, a combination of one or more of the following listed ET-1 to ET-57.

[0053]

[0054]

[0055] However, it is not limited to the above several materials.

[0056] According to an embodiment of the present invention, an electron injection layer is further included between the electron transport layer and the cathode in the organic electroluminescent device.

[0057] According to an embodiment of the present invention, the material of the electron injection layer is selected from one or more of LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, and Ca.

[0058] The present application has the following beneficial effects:

[0059] 1) The present invention provides an organic electroluminescent doping material and a light-emitting device. By introducing a deuterium atom group at a specific position on the thiophene ring, the molecular spacing and bond energy of the obtained compound are adjusted, and a doping material with a specific atomic structure is obtained. Applying the obtained doping material with a specific atomic structure to the organic electroluminescent device can significantly reduce the driving voltage and improve the light-emitting efficiency of the device.

[0060] 2) The organic electroluminescent material prepared by the present invention is used in the light-emitting layer of the organic electroluminescent device. Since the light-emitting material is a structure composed of a specific doping material and a host material, and is combined with the design of other layer materials, the turn-on and turn-off voltages of the organic electroluminescent device can be effectively reduced, and the efficiency of the device can be improved. Description of the Drawings

[0061] Figure 1 is the nuclear magnetic resonance hydrogen spectrum of Compound L AF -1 in the examples of the present invention. Detailed Embodiments

[0062] The technical solutions of the synthesis examples and embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0063] Synthesis Example 1

[0064] This synthesis example provides an organometallic compound I-1, and the specific synthesis steps are as follows: 1)

[0066]

[0067] Under a nitrogen protection system, weigh compound 1-bromo-2-chloro-4-iodo-3-methylbenzene (CAS: 1000573-57-8) (1700 mmol), deuterated benzene (170000 mmol), and trifluoromethanesulfonic acid (5100 mmol) and put them into the reaction system. Reflux for 18 h under nitrogen protection. After the reaction is completed, add heavy water to quench, extract with ethyl acetate, wash three times with saturated brine, concentrate under reduced pressure, and perform column chromatography (200 - 300 mesh, 6000 g) with the eluent DCM:PE = 1:10. Rotate the receiving solution until no liquid flows out to obtain the compound shown in Formula L AF -1 (461.19 g, yield 82%).

[0068] Perform the following analytical tests on the intermediate compound shown in Formula L AF -1:

[0069] HPLC purity: greater than 99.5%; Mass spectrometry: measured value is 330.92; 2)

[0071]

[0072] Under a nitrogen protection system, weigh the compound shown in Formula L AF -1 (1350 mmol), neopentylboronic acid (CAS: 701261-35-0) (1350 mmol), and anhydrous potassium carbonate (4050 mmol) and put them into the reaction system. Add 3600 ml of toluene, 1800 mL of absolute ethanol, and 1800 mL of purified water. Add Pd(PPh3)4 (27 mmol) under nitrogen protection and reflux at 100 °C for 22 h under nitrogen protection.

[0073] After the reaction is completed, separate the layers, extract with ethyl acetate, wash three times with saturated brine, and concentrate under reduced pressure. Dissolve in 600 ml of dichloromethane and perform column chromatography (200 - 300 mesh, 2900 g) with the eluent DCM:PE = 1:5. Rotate the receiving solution until no liquid flows out to obtain the compound shown in Formula L AE -1 (129.95 g, yield 35%). Perform the following analytical tests on the intermediate compound shown in Formula L AE -1:

[0074] HPLC purity: greater than 99.5%; Mass spectrometry: measured value is 275.18. 3)

[0076]

[0077] Under a nitrogen protection system, compound formula L AE -1 (470 mmol), bis(pinacolato)diboron (470 mmol), X-Phos (94 mmol), palladium(II) acetate (9.4 mmol), potassium acetate (1410 mmol) and dioxane (2850 mL) were successively added to the reaction system. The system was purged with N2 three times and protected with N2, and then heated and stirred at 100 °C overnight. After the reaction was completed, it was filtered through diatomaceous earth and anhydrous magnesium sulfate, washed twice with ethyl acetate, and the organic phase was collected and concentrated under reduced pressure to obtain the crude product intermediate of formula L AD -1 shown compound, which was directly used for the next step. 4)

[0079]

[0080] Under a nitrogen protection system, compound formula L AD -1 (470 mmol), cuprous bromide (470 mmol), anhydrous sodium methyl mercaptide (1410 mmol) were added to DMF (1850 mL), then water (185 mL) was added. The system was purged with N2 three times and protected with N2, and then heated and stirred at 140 °C for 41 h. After the reaction was completed, it was cooled to room temperature, the reaction solution was poured into 3 times the volume of water, and a solid was precipitated. The solid was filtered, dissolved in DCM, the filtrate was passed through a silica gel funnel, eluted with DCM, and the filtrate was evaporated to dryness to obtain the crude product intermediate of formula L AC -1 shown compound, which was directly used for the next reaction. 5)

[0082]

[0083] Under a nitrogen protection system, compound formula L AC -1 (470 mmol), 2-chloro-3-amino-4-bromopyridine (CAS: 1354021-09-2) (470 mmol), anhydrous potassium carbonate (1410 mmol) were placed in the reaction system, 3100 ml of toluene, 1550 mL of absolute ethanol, and 1550 mL of pure water were added. Pd(PPh3)4 (9.4 mmol) was added under nitrogen protection, and the mixture was refluxed at 100 °C for 23 h under nitrogen protection. After the reaction was completed, it was separated, extracted with ethyl acetate, washed three times with saturated brine, and concentrated under reduced pressure. 750 ml of dichloromethane was added to dissolve it, and the solution was column chromatographed (200 - 300 mesh, 2350 g) with the eluent DCM:PE = 1:2. The receiving solution was rotated until no liquid flowed out to obtain the compound of formula L AB -1 shown compound (67.89 g, yield 43%), and the intermediate compound of formula LAB -1 Perform the following analytical tests:

[0084] HPLC purity: greater than 99.5%; Mass spectrometry: The measured value is 335.96. 6)

[0086]

[0087] Under a nitrogen protection system, weigh compound L AB -1 (200 mmol) and dissolve it in THF (810 mL) in the reaction system. After heating to an internal temperature of 55 °C - 57 °C, stop heating, add copper acetate (200 mmol), and then carefully drop a 105 mL THF solution containing tert-butyl nitrite (240 mmol) into the above system. There is heat and gas evolution in the system. After the dropping is complete, keep the temperature for 1.5 h to end the reaction; directly concentrate the reaction solution under reduced pressure to dryness, then add DCM (1300 mL) and reflux to dissolve clearly. Filter the solution through a silica gel column, collect the column liquid, and concentrate it under reduced pressure to a remaining volume of about 90 mL. Solids will precipitate out. Cool to below 20 °C and filter, filter dry, and dry to obtain compound L AA -1 (25.00 g, yield 41%). For the intermediate compound L AA -1 Perform the following analytical tests:

[0088] HPLC purity: greater than 99.5%;

[0089] The measured value of mass spectrometry is 304.94. 7)

[0091]

[0092] Under a nitrogen protection system, weigh compound L AA -1 (80 mmol), [4-(tert-butyl)naphthalene]-2-boronic acid pinacol ester (CAS: 2217657-10-6) (96 mmol), and anhydrous potassium carbonate (240 mmol) into the reaction system, add 1200 ml of toluene, 600 mL of absolute ethanol, 600 mL of pure water, add Pd(PPh3)4 (1.6 mmol) under nitrogen protection, reflux at 100 °C for 23 h under nitrogen protection. After the reaction is completed, separate the layers, extract with ethyl acetate, wash three times with saturated brine, and concentrate under reduced pressure. Add 185 ml of dichloromethane to dissolve, subject the solution to column chromatography (200 - 300 mesh, 700 g) with the eluent DCM:PE = 1:4, and rotate the receiving solution until no liquid flows out to obtain the compound shown in L A -1 (22.79 g, yield 63%). For the intermediate compound L A -1 Perform the following analytical tests:

[0093] HPLC purity: greater than 99.5%;

[0094] Mass spectrometry: the measured value is 452.38;

[0095] Elemental analysis: the calculated values are C, 82.25; H, 7.57; N, 3.09; S, 7.08. The measured values are C, 82.26; H, 7.56; N, 3.08; S, 7.09. 8)

[0097]

[0098] Under a nitrogen protection system, weigh out the ligand L A -1 (52.8 mmol) and IrC13·3H2O (22 mmol) and place them into the reaction system. Add a mixed solution of 480 ml of ethylene glycol monoethyl ether and 160 ml of pure water. Reflux for 30 hours under nitrogen protection, then cool to room temperature. A precipitate will form. Filter the precipitate by suction, and wash and dry it successively with water, absolute ethanol, and petroleum ether to obtain the bridged ligand II-1 as a dark red powder (15.67 g, yield 63%). 9)

[0100]

[0101] Weigh out the bridged ligand II-1 (5.5 mmol), add potassium carbonate anhydrous (55 mmol), and then add 230 ml of ethylene glycol monoethyl ether to the system. Replace the nitrogen three times, and add the compound L B -1 (CAS: 872802-98-7) (16.5 mmol) under nitrogen. Reflux for 28 hours under nitrogen protection, cool down, filter by suction, wash with alcohol, and dry. Use dichloromethane as the solvent and column chromatography with neutral alumina. Concentrate the filtrate to precipitate the solid, and finally obtain the organophosphorus luminescent material shown in I-1 (4.17 g, yield 29%).

[0102] Analyze and test the obtained organometallic compound with the structure shown in I-1:

[0103] HPLC purity: greater than 99.5%;

[0104] Mass spectrometry: the measured value is 1306.72;

[0105] Elemental analysis: the calculated values are C, 68.93; H, 6.86; N, 2.14; O, 2.45; S, 4.91. The measured values are C, 68.91; H, 6.88; N, 2.15; O, 2.46; S, 4.90;

[0106] 11H NMR (400 MHz, Chloroform-d) δ 8.87 (d, 2H), 8.34 (dd, 2H), 8.01 – 7.94 (m, 2H), 7.81 (d, 2H), 7.70 (d, 2H), 7.54 (s, 2H), 7.45 (td, 2H), 7.37 (td, 2H), 5.65 (dd, 1H), 2.76 (pd, 1H), 2.62 (s, 4H), 2.48 (pd, 1H), 2.31 (s, 6H), 1.63 – 1.51 (m, 4H), 1.50 – 1.44 (m, 4H), 1.43 (d, 18H), 1.00 (d, 18H), 0.89 (t, 12H).

[0107] Synthesis Example 2

[0108] This synthesis example provides an organometallic compound I-193, that is, the compound numbered I-193. The specific synthesis steps are as follows:

[0109]

[0110] Among them, the synthesis method of formula II-193 is as shown in Synthesis Example 1 and will not be elaborated here.

[0111] Weigh the bridging ligand II-193 (5.5 mmol), add anhydrous potassium carbonate (55 mmol), and then add 240 ml of ethylene glycol monoethyl ether to the system. Replace nitrogen three times, and add the compound of formula L B -193 (CAS: 1821143-86-5) (22.0 mmol) under nitrogen. Reflux for 28 hours under nitrogen protection, cool down, filter by suction, wash with alcohol, and dry. Use dichloromethane as the solvent and carry out column chromatography on neutral alumina. Concentrate the filtrate to precipitate a solid, and finally obtain the organometallic compound shown in I-193 (3.79 g, with a yield of 27%). The organometallic compound I-193 was subjected to the following analysis and testing:

[0112] HPLC purity: greater than 99.5%;

[0113] Mass spectrometry: The measured value is 1362.75;

[0114] Elemental analysis: The calculated values are C, 69.62; H, 7.17; N, 2.06; O, 2.35; S, 4.70. The measured values are C, 69.63; H, 7.16; N, 2.07; O, 2.34; S, 4.71;

[0115] 11H NMR (400 MHz, Chloroform-d) δ 8.87 (d, 2H), 8.34 (dd, 2H), 8.01 –7.94 (m, 2H), 7.81 (d, 2H), 7.70 (d, 2H), 7.54 (s, 2H), 7.45 (td, 2H), 7.37(td, 2H), 5.61 (dd, 1H), 2.66 (td, 1H), 2.62 (s, 4H), 2.31 (s, 6H), 2.14(ddd, 1H), 2.00 (dq, 2H), 1.85 (dq, 2H), 1.45 – 1.40 (m, 18H), 1.04 – 0.97(m, 18H), 0.96 – 0.87 (m, 24H).

[0116] The present invention also provides an organic electroluminescent device, which contains the organic electroluminescent doping material of the present invention. More specifically, it contains an organic electroluminescent doping material of a compound having the structure shown in Chemical Formula I.

[0117] In order to further describe the present invention, the following more specific embodiments are listed.

[0118] Device Example 1

[0119] All the device assemblies of the embodiments are fabricated by thermal evaporation under high vacuum (<10 7 Torr). The anode electrode is 1200 Å indium tin oxide (ITO), and the cathode is composed of 10 Å of Liq (lithium 8-hydroxyquinoline) and then 1000 Å of Al. After the device is fabricated, it is immediately encapsulated with a glass cover sealed with epoxy resin in a nitrogen glove box (H2O and O2 < 1 ppm), and a desiccant is incorporated inside the package.

[0120] The organic stack of the device example is as follows in sequence: the ITO surface, 100 Å of HT-16 as the hole injection layer (HIL); 400 Å of HT-16 as the hole transport layer (HTL); 50 Å of EBM as the electron blocking layer (EBL); a 400 Å emission layer (EML) containing RH-01 as the red host and 3% of the emitter Compound I-1; 350 Å of Liq (lithium 8-hydroxyquinoline) doped with 35% of ET-16 as the electron transport layer (ETL). Table 2 shows the thickness and materials of the device layers.

[0121] Table 2: Materials and Thickness of Device Layers

[0122]

[0123] The structure is as follows:

[0124]

[0125] Device Example 2 - 12

[0126] The preparation method is the same as that of Example 1 above, except that: the doping material I - 1 is replaced with I - 5, I - 65, I - 119, I - 142, I - 169, I - 193, I - 197, I - 213, I - 245, I - 281, I - 293.

[0127] Device Comparative Example 1 - 4

[0128] The method for preparing the organic electroluminescent device is the same as that in Example 1 above, except that: the compounds of Comparative Example 1 - Comparative Example 4 are used to replace the compound shown in the doping material formula I - 1 in Example 1.

[0129] The compounds obtained in Comparative Example 1 - 4 are as follows:

[0130]

[0131] The driving voltage, luminous efficiency and lifetime of the organic electroluminescent devices obtained from the above device examples and device comparative examples were characterized at a brightness of 6000 (nits), and the test results are shown in Table 3 below:

[0132] Table 3

[0133]

[0134] As can be seen from Table 3, when the organic electroluminescent doping material compound prepared by the present invention is used as the light-emitting layer and applied to the organic electroluminescent device, compared with the organic electroluminescent device prepared in the comparative example, since the present invention selects a specific ligand compound, by introducing a deuterium atom group on the thiophene ring, the intermolecular spatial configuration, intermolecular spacing and bond energy are changed, the molecular orientation is set, and the device structure of the present invention is matched. Although the lifetime is not significantly improved compared with the comparative example, it can be clearly seen that the OLED device prepared by the present invention has the advantages of high efficiency and low driving voltage.

[0135] The above examples only list the effect data of the devices made of a part of the structural formulas. This is a representative sampling test. Judging from the experimental data, the overall data vary little and can represent the effects of other unlisted structures.

[0136] Those skilled in the art will clearly see that the present invention can have many modifications and variations without departing from the spirit and scope of the present invention. Therefore, it can be expected that the present invention covers the modifications and variations of the present invention provided within the scope of the appended claims and their equivalents.

[0137] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic electroluminescent doping material, characterized in that: Selected from one of the following structures:

2. An organic electroluminescent device, comprising a first electrode, a second electrode, and an organic material layer located between the first electrode and the second electrode; the organic material layer includes a hole transport region, a light-emitting layer, and an electron transport region; characterized in that: The light-emitting layer contains the organic electroluminescent doping material described in claim 1.

3. The organic electroluminescent device according to claim 2, characterized in that: The hole transport region is a single-layer hole transport layer, and the single-layer hole transport layer is a single-layer hole transport layer containing only one compound or a single-layer hole transport layer containing multiple compounds; Alternatively, the hole transport region includes a multi-layer structure of at least one of a hole injection layer, a hole transport layer, and an electron blocking layer.

4. The organic electroluminescent device according to claim 2, wherein: The electron transport region is a single-layer electron transport layer, and the single-layer electron transport layer is a single-layer electron transport layer containing only one compound or a single-layer electron transport layer containing multiple compounds; Alternatively, the electron transport region includes a multi-layer structure of at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

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