Organic electroluminescent material and preparation method and application thereof

Abstract

The present invention belongs to the field of organic photoelectric materials, and discloses an organic electroluminescent material and a preparation method and application thereof. The structure of the organic electroluminescent material is shown in Formula I: The compound provided by the present invention can be used as a doping material for a light-emitting layer. By selecting a specific ligand compound and substituting a specific substituent at the 3-position of dibenzothiophene, the spatial configuration and stereostructure between molecules can be changed, and the molecular orientation can be set. It has the advantages of improving the turn-on voltage and the special device performance of low driving voltage, improving the crosstalk phenomenon between sub-pixels, and making the OLED device have the advantages of long life, high efficiency and low driving voltage.

Description

Technical Field

[0001] The invention belongs to the field of organic photoelectric materials, and in particular relates to an organic electroluminescent material and a preparation method and application thereof. Background Art

[0002] Organic electroluminescent display (OLED) is an active light-emitting display device with the advantages of simple preparation process, low cost, high contrast, wide viewing angle, low power consumption, etc. Optoelectronic devices using organic materials are becoming more and more popular.

[0003] The performance of the materials used to make OLED display devices will affect the performance of the display screen. Generally, organic photoelectroluminescent materials need to have the following performance requirements: 1. High luminous efficiency; 2. Excellent electron and hole stability; 3. Suitable luminous color; 4. Low driving voltage; 5. Suitable turn-on voltage; 6. Excellent film processing properties.

[0004] In existing OLED display devices, the turn-on voltages of the RGB sub-pixels are inconsistent. The turn-on voltage is defined as the voltage at which the device luminance reaches 1cd / m 2 The voltage required to be applied when the light is on. A low turn-on voltage will cause crosstalk between sub-pixels at low grayscale. At the same time, obtaining the best luminous efficiency of the device under low driving voltage conditions is a common demand in the OLED field. Reducing the driving voltage is an important way to reduce power consumption, improve device luminous efficiency and stability, and other issues.

[0005] Therefore, how to obtain an organic electroluminescent material with a high turn-on voltage and a relatively low driving voltage is a problem that those skilled in the art need to solve urgently. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide an organic electroluminescent material with high turn-on voltage and relatively low driving voltage, thereby obtaining an organic electroluminescent device with high efficiency and long life.

[0007] In order to achieve the above-mentioned purpose, the first object of the present invention is to provide an organic electroluminescent material. The following technical scheme is adopted:

[0008] An organic electroluminescent material has a molecular formula of Ir(LA)2(LB) and has a structure of Formula I:

[0009] ;

[0010] In the general formula, R is selected from any one of -D (deuterium), -T (tritium), -F, -CN, -CT3, -CF3, -CH2F, -CHF2, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted 4-24 membered aromatic heterocyclic group;

[0011] R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 Independently selected from -H, -D (deuterium), -T (tritium), -F, -CN, -CD3, -CT3, -CF3, -CH2F, -CHF2, -Ge(Me)3, -Si(Me)3, any one of substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, and substituted or unsubstituted 4-24 membered aromatic heterocyclic group.

[0012] It should be noted that the organic electroluminescent device provided by the present invention adopts a doping material with a specific atomic structure, and introduces a substituent at the 3-position of dibenzothiophene to adjust the spatial stereo configuration and size of the molecular structure of the obtained compound, so that the obtained organic compound has a long life, high efficiency, low driving voltage, and can increase the turn-on voltage after being used in the organic electroluminescent device.

[0013] Furthermore, all atoms in the above groups may be substituted by deuterium.

[0014] Further, R is selected from -D, -F, -CN, -CF3, -CH2F, -CHF2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, terphenyl, fluorenyl, phenanthryl, triphenylene, furyl, benzofuranyl, benzothienyl, dibenzofuranyl, dibenzothienyl or any one of the following substituents:

[0015] ;

[0016] R1-R 11independently selected from -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, Any one of phenanthryl, anthracenyl, indenyl, triphenylene, fluoranthene, furanyl, thienyl, imidazolyl, pyrazolyl, thiazolyl, pyridyl, pyrazinyl, pyrimidinyl, benzofuranyl, benzothienyl, isobenzofuranyl, dibenzofuranyl, dibenzothienyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl and carbazolyl.

[0017] Furthermore, R is selected from methyl, ethyl, -F, -CN, -CF3 or any one of the following substituents:

[0018] ;

[0019] R1 is hydrogen, methyl, ethyl, -F, -CN, -CF3 or any one of the following substituents: ;

[0020] R2 and R3 are independently selected from -H or -D.

[0021] It is worth noting that in the present invention, * represents the connection position; "substituted" means that it can be replaced by -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, The benzothiophene group may be substituted with biphenyl, terphenyl, naphthyl, fluorenyl, phenanthryl, anthracenyl, indenyl, triphenylene, fluoranthene, furanyl, thienyl, imidazolyl, pyrazolyl, thiazolyl, pyridyl, pyrazinyl, pyrimidinyl, benzofuranyl, benzothiophenyl, isobenzofuranyl, dibenzofuranyl, dibenzothienyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, carbazolyl, or the like.

[0022] Furthermore, the organic electroluminescent material is selected from one of the following structures:

[0023] .

[0024] The second object of the present invention is to provide a method for preparing the organic electroluminescent material as described above, the specific operations are as follows:

[0025] 1. Under nitrogen protection, the ligand LA structure compound and IrC13·3H2O are placed in a reaction system, and a mixed solution of ethylene glycol ethyl ether and purified water is added. The mixture is refluxed under nitrogen protection, and then cooled to room temperature. A precipitate is precipitated. The precipitate is filtered, washed and dried with water, anhydrous ethanol, and petroleum ether in sequence to obtain a bridging ligand compound shown in the intermediate formula II;

[0026] 2. Weigh the intermediate compound of formula II and anhydrous potassium carbonate, add ethylene glycol ethyl ether, and then add the ligand compound of formula LB. Under nitrogen protection, reflux reaction, filter, wash with alcohol, and dry. Use dichloromethane as solvent, use silica gel column chromatography, concentrate the filtrate and precipitate solid to obtain the compound shown in formula I.

[0027] The specific synthetic route is as follows:

[0028] ;

[0029] Among them, R, R1-R 11 The representative groups are the same as mentioned above.

[0030] The third object of the present invention is to provide an application of an organic electroluminescent material. The organic electroluminescent material as described above is applied to an organic electroluminescent device and can be used as a doping material in a light-emitting layer.

[0031] Compared with the prior art, the present invention provides an organic electroluminescent material and a preparation method and application thereof, which have the following excellent effects:

[0032] 1. By introducing a substituent group at the 3-position of dibenzothiophene, the spatial structure size and morphology of the resulting substance can be adjusted, which has the special device performance of improving the turn-on voltage and low driving voltage, improving the crosstalk phenomenon between sub-pixels, and making the OLED device have the advantages of long life, high efficiency and low driving voltage.

[0033] 2. In the study of the diketone ligand part of the iridium complex, a complete theoretical system has not yet been formed. Because the carbon atoms on the side chain do not participate in conjugation, they have a certain influence on the electron cloud distribution but the influence is not significant. At the same time, the study found that the length, configuration, and group size of the side chain alkyl group will have a certain degree of influence on the performance indicators such as the wavelength, half-peak width, efficiency, life, and CIE coordinates of the doped material. More importantly, for different red light host (RH) materials, the molecular structure of the diketone ligand is regulated to match RH with the red light doping material (RD). At present, this matching basically has no directional guidance and needs to be verified through massive experiments.

[0034] In summary, the light-emitting layer of the organic electroluminescent device adopts the doping material shown in Formula I of the present invention and the structure formed with the main material, and is combined with other layer materials to enable the obtained organic electroluminescent device to effectively increase the turn-on voltage, maintain a lower driving voltage, improve the crosstalk phenomenon between sub-pixels, improve efficiency, and improve the problem of low lifespan. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0036] Figure 1 This is a brightness-voltage test diagram of the organic electroluminescent device prepared from Compound I-3 and Comparative Example 5.

[0037] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of compound 1-3. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the related drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The invention specifically discloses an organic electroluminescent material and a preparation method and application thereof.

[0040] The following will be described clearly and completely in conjunction with the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides an organometallic compound Ⅰ-1, that is, a compound numbered Ⅰ-1, and the specific synthesis steps are as follows:

[0043] ;

[0044] Under nitrogen protection, weigh the compound 1-bromo-2-chloro-4-iodo-3-methylbenzene (CAS: 1000573-57-8) (950mmol), isobutylboric acid (CAS: 84110-40-7) (950mmol), anhydrous potassium carbonate (990mmol) and put it into the reaction system, add 2000ml toluene, 1000mL anhydrous ethanol, 1000mL pure water, add Pd(PPh3)4 (9.5mmol) under nitrogen protection, reflux at 100℃ for 25h under nitrogen protection, after the reaction is completed, separate the liquid, extract with ethyl acetate, wash three times with saturated brine, and concentrate under reduced pressure. Add 400ml of dichloromethane to dissolve, and the solution is column chromatographed (200-300 mesh, 900g) with the developing agent DCM:PE=1:2, and the receiving liquid is vortexed until no liquid flows out to obtain the compound shown in formula L AE -1 (93.8 g, yield 37.9%), the intermediate compound formula L AE -1 Carry out the following analysis tests:

[0045] HPLC purity: greater than 99.5%;

[0046] Mass spectrum: Test value is 260.12.

[0047] ;

[0048] Under nitrogen protection system, compound formula LAE -1 (360mmol), biboric acid pinacol ester (360mmol), X-Phos (72mmol), palladium acetate (7.2mmol), potassium acetate (1080mmol) and dioxane (1200mL) were added to the reaction system, replaced by N2 three times and protected by N2, heated and stirred at 100°C overnight. After the reaction was completed, diatomaceous earth and anhydrous magnesium sulfate were filtered, washed twice with ethyl acetate, and the organic phase was collected and concentrated under reduced pressure to obtain a crude product intermediate of formula L AD -1 is used directly in the next step.

[0049] ;

[0050] Under nitrogen protection system, compound formula L AD -1 (360mmol), cuprous bromide (360mmmol), anhydrous sodium methylthiolate (1080mmol), added to DMF (900mL), then added water (90mL), N2 replaced three times and N2 protected, heated and stirred at 140°C for 48h. After the reaction was completed, cooled to room temperature, the reaction solution was poured into 3 times the volume of water, solid precipitated, filtered, the solid was dissolved with DCM, the filtrate was passed through a silica gel funnel, DCM was rinsed, and the filtrate was spin-dried to obtain a crude product intermediate of formula L AC -1 was directly used in the next reaction.

[0051] ;

[0052] Under nitrogen protection system, weigh compound formula L AC -1 (360mmol), 2-chloro-3-amino-4-bromopyridine (CAS: 1354021-09-2) (360mmol), anhydrous potassium carbonate (1080mmol) were placed in the reaction system, 2600ml toluene, 1300mL anhydrous ethanol, 1300mL purified water were added, Pd (PPh3) 4 (7.2mmol) was added under nitrogen protection, refluxed at 100 ° C for 26h under nitrogen protection, after the reaction was completed, the liquid was separated, extracted with ethyl acetate, washed with saturated brine three times, and concentrated under reduced pressure. 400ml of dichloromethane was added to dissolve, the solution was column chromatographed (200-300 mesh, 1000g) with a developing agent of DCM: PE = 1:1, and the receiving liquid was vortexed until no liquid flowed out to obtain the compound shown in formula L AB -1 (55.3 g, yield 48.2%), the intermediate compound formula L AB -1 Carry out the following analysis tests:

[0053] HPLC purity: greater than 99.5%;

[0054] Mass spectrum: Test value is 320.26.

[0055] ;

[0056] Under nitrogen protection system, weigh compound formula L AB -1 (170mmol) was dissolved in THF (700mL) in the reaction system. After the temperature reached 55°C to 57°C, the heating was stopped, copper acetate (170mmol) was added, and then 90mL of THF solution containing tert-butyl nitrite (204mmol) was carefully dripped into the above system. The system released heat and gas. After the addition was completed, the temperature was kept for 1.5h to complete the reaction. The reaction solution was directly concentrated to dryness under reduced pressure, and then DCM (900mL) was added to reflux and dissolve until it became clear. The solution was passed through a silica gel column. After the column liquid was collected, it was concentrated under reduced pressure to a remaining volume of about 100ml. After solid precipitation, the temperature was lowered to below 20°C, filtered, drained, and dried to obtain compound L AA -1 (22.1 g, yield 45.1%), the intermediate compound formula L AA -1 Carry out the following analysis tests:

[0057] HPLC purity: greater than 99.5%;

[0058] The mass spectrometry test value was 289.42.

[0059] ;

[0060] Under nitrogen protection system, weigh compound formula L AA -1 (75mmol), [4-(tert-butyl) naphthalene] -2-boronic acid pinacol ester (CAS: 2217657-10-6) (82.5mmol), anhydrous potassium carbonate (225mmol) were put into the reaction system, 1200ml toluene, 600mL anhydrous ethanol, 600mL purified water were added, Pd (PPh3) 4 (1.5mmol) was added under nitrogen protection, refluxed at 100 ° C for 24h under nitrogen protection, after the reaction was completed, the liquid was separated, extracted with ethyl acetate, washed with saturated brine three times, and concentrated under reduced pressure. 200ml of dichloromethane was added to dissolve, the solution was column chromatographed (200-300 mesh, 600g) with the developing agent DCM: PE = 1:5, and the receiving liquid was vortexed until no liquid flowed out to obtain the compound shown in formula L A -1 (22.3 g, yield 68.1%), the intermediate compound formula L A -1 Carry out the following analysis tests:

[0061] HPLC purity: greater than 99.5%;

[0062] Mass spectrum: test value is 437.39;

[0063] Elemental Analysis:

[0064] Calculated values: C, 82.33; H, 7.14; N, 3.20; S, 7.33.

[0065] The test values ​​are C, 82.35; H, 7.12; N, 3.21; S, 7.32.

[0066] ;

[0067] Under nitrogen protection system, weigh the ligand formula L A -1 (48.4mmol), IrC13·3H2O (22mmol) were put into the reaction system, and a mixed solution of 450ml of ethylene glycol ethyl ether and 150ml of pure water was added. The mixture was refluxed for 28 hours under nitrogen protection, and then cooled to room temperature. A precipitate was precipitated. The precipitate was filtered, washed with water, anhydrous ethanol and petroleum ether in turn, and dried to obtain a dark red powder of the bridged ligand Ⅱ-1 (14.52, yield 59.8%).

[0068] ;

[0069] Weigh the bridged ligand II-1 (5.5 mmol), add anhydrous potassium carbonate (55 mmol), then add 190 ml of ethylene glycol ether to the system, replace nitrogen three times, and add formula L under nitrogen. B Compound (CAS: 2891969-73-4) (16.5 mmol), under nitrogen protection, reflux for 23 hours, cool, filter, wash with alcohol, and dry. Use dichloromethane as solvent, use neutral alumina column chromatography, concentrate the filtrate to precipitate solid, and finally obtain the luminescent material shown in Ⅰ-1 (4.3 g, yield 29.4%);

[0070] The organometallic compound I-1 was subjected to the following analytical tests:

[0071] HPLC purity: greater than 99.5%;

[0072] Mass spectrum: test value is 1332.75;

[0073] Elemental Analysis:

[0074] Calculated values ​​are C, 69.38; H, 6.88; N, 2.10; O, 2.40; S, 4.81.

[0075] The test values ​​are C, 69.39; H, 6.87; N, 2.11; O, 2.41; S, 4.80;

[0076] 1H NMR (400 MHz, Chloroform-d) δ 8.87 (d, 2H), 8.34 (dd, 2H), 7.98(dd, 2H), 7.81 (d, 2H), 7.71 (d, 2H), 7.62 (s, 2H), 7.45 (td, 2H), 7.37 (td,2H), 7.27 (d, 2H), 5.68 (dd, 1H), 2.78 (pd, 1H), 2.60 – 2.51 (m, 5H), 2.29(s, 6H), 1.90 (dp, 2H), 1.74 (dq, 2H), 1.62 – 1.39 (m, 26H), 0.93 – 0.84 (m, 18H), 0.83 (dd, 12H).

[0077] Example 2

[0078] This embodiment provides an organometallic compound I-3, i.e., a compound numbered I-3, and the specific synthesis steps are as follows:

[0079] ;

[0080] Under nitrogen protection system, weigh the compound 1-bromo-2-chloro-4-iodo-3-methylbenzene (CAS: 1000573-57-8) (1380mmol), neopentylboronic acid (CAS: 701261-35-0) (1380mmol), anhydrous potassium carbonate (4140mmol) and put them into the reaction system, add 2500ml toluene, 1250mL anhydrous ethanol, 1250mL purified water, add Pd(PPh3)4 (27.6mmol) under nitrogen protection, reflux at 100℃ for 25h under nitrogen protection, after the reaction is completed, separate the liquid, extract with ethyl acetate, wash three times with saturated brine, and concentrate under reduced pressure. Add 600ml dichloromethane to dissolve, and the solution is column chromatographed (200-300 mesh, 1000g) with developing agent DCM:PE=1:4, and the receiving liquid is vortexed until no liquid flows out to obtain the compound shown in formula L AE -3 (121.0 g, yield 32.1%), the intermediate compound formula L AE -3 Carry out the following analysis tests:

[0081] HPLC purity: greater than 99.5%;

[0082] Mass spectrum: Test value is 274.15.

[0083] ;

[0084] Under nitrogen protection system, compound formula LAE -3 (440mmol), biboric acid pinacol ester (440mmol), X-Phos (88mmol), palladium acetate (8.8mmol), potassium acetate (1320mmol) and dioxane (2000mL) were added to the reaction system, replaced by N2 three times and protected by N2, and heated and stirred at 100°C overnight. After the reaction was completed, diatomaceous earth and anhydrous magnesium sulfate were filtered, washed twice with ethyl acetate, and the organic phase was collected and concentrated under reduced pressure to obtain a crude product intermediate of formula L AD -3 is used directly in the next step.

[0085] ;

[0086] Under nitrogen protection system, compound formula L AD -3 (440mmol), cuprous bromide (440mmmol), anhydrous sodium methylthiolate (1320mmol), added to DMF (1500mL), then added water (150mL), N2 replaced three times and N2 protected, heated and stirred at 140°C for 45h. After the reaction was completed, cooled to room temperature, the reaction solution was poured into 3 times the volume of water, solid precipitated, filtered, the solid was dissolved with DCM, the filtrate was passed through a silica gel funnel, DCM was rinsed, and the filtrate was spin-dried to obtain a crude product intermediate of formula L AC -3 was directly used in the next reaction.

[0087] ;

[0088] Under nitrogen protection system, weigh compound formula L AC -3 (440mmol), 2-chloro-3-amino-4-bromopyridine (CAS: 1354021-09-2) (440mmol), anhydrous potassium carbonate (1320mmol) were put into the reaction system, 2800ml toluene, 1400mL anhydrous ethanol, 1400mL purified water were added, Pd (PPh3) 4 (8.8mmol) was added under nitrogen protection, refluxed at 100 ° C for 22h under nitrogen protection, after the reaction was completed, the liquid was separated, extracted with ethyl acetate, washed with saturated brine three times, and concentrated under reduced pressure. 700ml of dichloromethane was added to dissolve, the solution was column chromatographed (200-300 mesh, 1200g) with the developing agent DCM: PE = 1:2, and the receiving liquid was vortexed until no liquid flowed out to obtain the compound shown in formula L AB -3 (72.1 g, yield 49.3%), the intermediate compound formula L AB -3 Carry out the following analysis tests:

[0089] HPLC purity: greater than 99.5%;

[0090] Mass spectrum: Test value is 334.28.

[0091] ;

[0092] Under nitrogen protection system, weigh compound formula L AB -3 (215mmol) was dissolved in THF (800mL) in the reaction system. After the temperature reached 55°C to 57°C, the heating was stopped, copper acetate (215mmol) was added, and then 120mL of THF solution containing tert-butyl nitrite (258mmol) was carefully dripped into the above system. The system released heat and gas. After the addition was completed, the temperature was kept for 1.5h to complete the reaction. The reaction solution was directly concentrated to dryness under reduced pressure, and then DCM (1000mL) was added to reflux and dissolve until it became clear. The solution was passed through a silica gel column. After the column liquid was collected, it was concentrated under reduced pressure to a remaining volume of about 100ml. After solid precipitation, the temperature was lowered to below 20°C, filtered, drained, and dried to obtain compound L AA -3 (27.4 g, yield 42.3%), the intermediate compound formula L AA -3 Carry out the following analysis tests:

[0093] HPLC purity: greater than 99.5%;

[0094] The mass spectrometry test value is 303.26.

[0095] ;

[0096] Under nitrogen protection system, weigh compound formula L AA -3 (90mmol), [4-(tert-butyl) naphthalene] -2-boronic acid pinacol ester (CAS: 2217657-10-6) (99mmol), anhydrous potassium carbonate (270mmol) were put into the reaction system, 1500ml toluene, 750ml anhydrous ethanol, 750ml purified water were added, Pd (PPh3) 4 (1.8mmol) was added under nitrogen protection, refluxed at 100 ° C for 20h under nitrogen protection, after the reaction was completed, the liquid was separated, extracted with ethyl acetate, washed with saturated brine three times, and concentrated under reduced pressure. 200ml of dichloromethane was added to dissolve, the solution was column chromatographed (200-300 mesh, 700g) with the developing agent DCM: PE = 1:4, and the receiving liquid was vortexed until no liquid flowed out to obtain the compound shown in formula L A -3 (23.2 g, yield 57.3%), the intermediate compound formula L A -3 Carry out the following analysis tests:

[0097] HPLC purity: greater than 99.5%;

[0098] Mass spectrum: Test value is 451.37;

[0099] Elemental Analysis:

[0100] Calculated values: C, 82.44; H, 7.36; N, 3.10; S, 7.10.

[0101] The test values ​​are C, 82.46; H, 7.32; N, 3.11; S, 7.11.

[0102] ;

[0103] Under nitrogen protection system, weigh the ligand formula L A -3 (50mmol), IrC13·3H2O (22mmol) were put into the reaction system, and a mixed solution of 480ml of ethylene glycol ethyl ether and 160ml of pure water was added. The mixture was refluxed for 30 hours under nitrogen protection, and then cooled to room temperature. A precipitate was precipitated. The precipitate was filtered, washed with water, anhydrous ethanol and petroleum ether in turn, and dried to obtain a dark red powder of the bridged ligand Ⅱ-3 (14.2, yield 57.4%).

[0104] ;

[0105] Weigh the bridged ligand II-3 (5.5 mmol), add anhydrous potassium carbonate (55 mmol), then add 200 ml of ethylene glycol ether to the system, replace nitrogen three times, and add formula L under nitrogen. B Compound (CAS: 2891969-73-4) (22 mmol), under nitrogen protection, reflux for 23 hours, cool, filter, wash with alcohol, and dry. Use dichloromethane as solvent, use neutral alumina column chromatography, concentrate the filtrate to precipitate solid, and finally obtain the luminescent material shown in Ⅰ-3 (5.1 g, yield 34.1%);

[0106] The organometallic compound I-3 was subjected to the following analytical tests:

[0107] HPLC purity: greater than 99.5%;

[0108] Mass spectrum: test value is 1360.87;

[0109] Elemental Analysis:

[0110] Calculated values ​​are C, 69.72; H, 7.04; N, 2.06; O, 2.35; S, 4.71.

[0111] The test values ​​are C, 69.74; H, 7.02; N, 2.06; O, 2.32; S, 4.74.

[0112] Figure 2 It is the hydrogen nuclear magnetic resonance spectrum of compound I-3.

[0113] Example 3

[0114] This embodiment provides an organometallic compound I-70, that is, a compound numbered I-70, and the specific synthesis steps are as follows:

[0115] ;

[0116] Among them, formula L AA -70 is prepared as in Example 2, formula L A -1 is shown and will not be repeated here.

[0117] Under nitrogen protection system, weigh compound formula L AA -70 (100 mmol), deuterated benzene (10000 mmol), trifluoromethanesulfonic acid (300 mmol) were put into the reaction system, refluxed under nitrogen protection for 18 h, after the reaction was completed, heavy water was added to quench, extracted with ethyl acetate, washed with saturated brine three times, concentrated under reduced pressure, column chromatography (200-300 mesh, 600 g) with developing agent DCM:PE=1:10, the receiving solution was vortexed until no liquid flowed out, and the compound shown in formula L was obtained. A -70 (23.9 g, yield 51.9%), the intermediate compound formula L A -70 The following analytical tests were performed:

[0118] HPLC purity: greater than 99.5%;

[0119] Mass spectrum: test value is 460.43;

[0120] Elemental Analysis:

[0121] Calculated values: C, 80.82; H, 9.19; N, 3.04; S, 6.96.

[0122] The test values ​​are C, 80.84; H, 9.17; N, 3.06; S, 6.94.

[0123] ;

[0124] Under nitrogen protection system, weigh the ligand formula L A -70 (55mmol), IrC13·3H2O (22mmol) were put into the reaction system, and a mixed solution of 540ml of ethylene glycol ethyl ether and 180ml of pure water was added. The mixture was refluxed for 32 hours under nitrogen protection, and then cooled to room temperature. A precipitate was precipitated. The precipitate was filtered, washed with water, anhydrous ethanol and petroleum ether in turn, and dried to obtain a dark red powder of the bridged ligand Ⅱ-70 (14.80g, yield 58%).

[0125] ;

[0126] Weigh the bridged ligand II-70 (5.5 mmol), add anhydrous potassium carbonate (55 mmol), then add 190 ml of ethylene glycol ether to the system, replace nitrogen three times, and add formula L under nitrogen. B Compound (CAS: 2891969-73-4) (11 mmol), under nitrogen protection, reflux for 36 hours, cool, filter, wash with alcohol, and dry. Use dichloromethane as solvent, use neutral alumina column chromatography, concentrate the filtrate to precipitate solid, and finally obtain the luminescent material shown in Ⅰ-70 (4.7 g, yield 31.2%);

[0127] The organometallic compound I-70 was subjected to the following analytical tests:

[0128] HPLC purity: greater than 99.5%;

[0129] Mass spectrum: test value is 1378.95;

[0130] Elemental Analysis:

[0131] Calculated values ​​are C, 68.80; H, 8.26; N, 2.03; O, 2.32; S, 4.65;

[0132] The test values ​​are C, 68.82; H, 8.24; N, 2.03; O, 2.35; S, 4.62.

[0133] 1 H NMR (400 MHz, Chloroform-d) δ 5.60 (dd, 1H), 2.78 (d, 1H), 2.66 –2.51 (m, 5H), 2.32 (s, 6H), 1.74 (dq, 2H), 1.62 – 1.37 (m, 26H), 1.03 – 0.99(m, 18H), 0.93 – 0.86(m, 18H).

[0134] Example 4

[0135] This embodiment provides an organometallic compound I-99, i.e., a compound numbered I-99, and the specific synthesis steps are as follows:

[0136] ;

[0137] Under nitrogen protection system, weigh the compound 2-bromo-1-chloro-4-iodobenzene (CAS: 31928-46-8) (1500mmol), neopentylboric acid (CAS: 701261-35-0) (1500mmol), anhydrous potassium carbonate (4500mmol) and put it into the reaction system, add 3000ml toluene, 1500mL anhydrous ethanol, 1500mL pure water, add Pd(PPh3)4 (30mmol) under nitrogen protection, reflux at 100℃ for 25h under nitrogen protection, after the reaction is completed, separate the liquid, extract with ethyl acetate, wash with saturated brine three times, and concentrate under reduced pressure. Add 900ml dichloromethane to dissolve, and the solution is column chromatographed (200-300 mesh, 1250g) with developing agent DCM:PE=1:6, and the receiving liquid is vortexed until no liquid flows out to obtain the compound shown in formula L AE -99 (128.70 g, yield 33%), the intermediate compound formula L AE -99 performs the following analysis tests:

[0138] HPLC purity: greater than 99.5%;

[0139] Mass spectrum: Test value is 260.17.

[0140] ;

[0141] Under nitrogen protection system, compound formula L AE -99 (490mmol), cuprous bromide (490mmmol), anhydrous sodium methylthiolate (1470mmol) were added to DMF (1300mL), and then water (130mL) was added, and N2 was replaced three times and N2 was protected, and the reaction was stirred at 140°C for 45h. After the reaction was completed, it was cooled to room temperature, and the reaction solution was poured into 3 times the volume of water to precipitate solids, filtered, and the solids were dissolved with DCM. The filtrate was passed through a silica gel funnel, rinsed with DCM, and the filtrate was spin-dried to obtain a crude product intermediate of formula L AD -99 was directly used in the next reaction.

[0142] ;

[0143] Under nitrogen protection system, compound formula L AD -99 (490mmol), biboric acid pinacol ester (490mmol), X-Phos (98mmol), palladium acetate (9.8mmol), potassium acetate (1470mmol) and dioxane (1500mL) were added to the reaction system, replaced with N2 three times and protected with N2, and heated and stirred at 100°C overnight. After the reaction was completed, the mixture was filtered with diatomaceous earth and anhydrous magnesium sulfate, washed twice with ethyl acetate, and the organic phase was collected and concentrated under reduced pressure to obtain a crude product intermediate of formula L AC-99 is used directly in the next step.

[0144] ;

[0145] Under nitrogen protection system, weigh compound formula L AC -99 (490mmol), 2-chloro-3-amino-4-bromopyridine (CAS: 1354021-09-2) (490mmol), anhydrous potassium carbonate (1470mmol) were placed in the reaction system, 2900ml toluene, 1450mL anhydrous ethanol, 1450mL purified water were added, Pd (PPh3) 4 (9.8mmol) was added under nitrogen protection, refluxed at 100 ° C for 28h under nitrogen protection, after the reaction was completed, the liquid was separated, extracted with ethyl acetate, washed with saturated brine three times, and concentrated under reduced pressure. 400ml of dichloromethane was added to dissolve, the solution was column chromatographed (200-300 mesh, 1000g) with a developing agent of DCM: PE = 1:1, and the receiving liquid was vortexed until no liquid flowed out to obtain the compound shown in formula L AB -99 (69.02 g, yield 44%), the intermediate compound formula L AB -99 performs the following analysis tests:

[0146] HPLC purity: greater than 99.5%;

[0147] Mass spectrum: Test value is 320.26.

[0148] ;

[0149] Under nitrogen protection system, weigh compound formula L AB -99 (215 mmol) was dissolved in THF (950 mL) in the reaction system. After the temperature reached 55°C to 57°C, the heating was stopped, copper acetate (215 mmol) was added, and then 95 mL of THF solution containing tert-butyl nitrite (258 mmol) was carefully dripped into the above system. The system released heat and gas. After the addition was completed, the temperature was kept for 2.5 h to complete the reaction. The reaction solution was directly concentrated to dryness under reduced pressure, and then DCM (1000 mL) was added to reflux and dissolve until it became clear. The solution was passed through a silica gel column. After the column liquid was collected, it was concentrated under reduced pressure to a remaining volume of about 100 ml. After solid precipitation, the temperature was lowered to below 20°C, filtered, drained, and dried to obtain compound L AA -99 (24.91 g, yield 40%), the intermediate compound formula L AA -99 performs the following analysis tests:

[0150] HPLC purity: greater than 99.5%;

[0151] The mass spectrometry test value was 289.26.

[0152] ;

[0153] Under nitrogen protection system, weigh compound formula L AA -99 (85mmol), [4-(tert-butyl) naphthalene] -2-boronic acid pinacol ester (CAS: 2217657-10-6) (102mmol), anhydrous potassium carbonate (255mmol) were placed in the reaction system, 1500ml toluene, 750ml anhydrous ethanol, 750ml purified water were added, Pd (PPh3) 4 (1.7mmol) was added under nitrogen protection, and refluxed at 100 ° C for 27h under nitrogen protection. After the reaction was completed, the liquid was separated, extracted with ethyl acetate, washed with saturated brine three times, and concentrated under reduced pressure. 200ml of dichloromethane was added to dissolve, and the solution was column chromatographed (200-300 mesh, 800g) with a developing agent of DCM: PE = 1:5, and the receiving liquid was vortexed until no liquid flowed out to obtain the compound shown in formula L A -99 (22.3 g, yield 60.2%), the intermediate compound formula L A -99 performs the following analysis tests:

[0154] HPLC purity: greater than 99.5%;

[0155] Mass spectrum: test value is 437.37;

[0156] Elemental Analysis:

[0157] Calculated values: C, 82.33; H, 7.14; N, 3.20; S, 7.33.

[0158] The test values ​​are C, 82.35; H, 7.12; N, 3.22; S, 7.32.

[0159] ;

[0160] Under nitrogen protection system, weigh the ligand formula L A -99 (55mmol), IrC13·3H2O (22mmol) were put into the reaction system, and a mixed solution of 480ml of ethylene glycol ethyl ether and 160ml of pure water was added. The mixture was refluxed for 29 hours under nitrogen protection, and then cooled to room temperature. A precipitate was precipitated. The precipitate was filtered, washed with water, anhydrous ethanol and petroleum ether in turn, and dried to obtain the bridged ligand Ⅱ-99 (15.49g, yield 64%).

[0161] ;

[0162] Weigh the bridged ligand II-99 (5.5 mmol), add anhydrous potassium carbonate (55 mmol), then add 230 ml of ethylene glycol ether to the system, replace nitrogen three times, and add formula L under nitrogen.B Compound (CAS: 2891969-73-4) (19.25 mmol), under nitrogen protection, reflux for 26 hours, cool, filter, wash with alcohol, and dry. Use dichloromethane as solvent, use neutral alumina column chromatography, concentrate the filtrate to precipitate solid, and finally obtain the luminescent material shown in Ⅰ-99 (3.6 g, yield 25%);

[0163] The organometallic compound I-99 was subjected to the following analytical tests:

[0164] HPLC purity: greater than 99.5%;

[0165] Mass spectrum: test value is 1332.74;

[0166] Elemental Analysis:

[0167] Calculated values ​​are C, 69.38; H, 6.88; N, 2.10; O, 2.40; S, 4.81;

[0168] The test values ​​are C, 69.39; H, 6.87; N, 2.11; O, 2.41; S, 4.80;

[0169] 1 H NMR (400 MHz, Chloroform-d) δ 8.88 (d, 2H), 8.34 (dd, 2H), 7.98(dd, 2H), 7.89 – 7.84 (m, 4H), 7.82 (d, 2H), 7.57 (s, 2H), 7.45 (td, 2H),7.37 (td, 2H), 7.23 (dd, 2H), 5.68 (dd, 1H), 2.78 (pd, 1H), 2.55 (pd, 1H),2.48 (s, 4H), 1.74 (dh, 2H), 1.61 – 1.39 (m, 26H), 0.98 – 0.92 (m, 18H), 0.92– 0.86 (m, 18H).

[0170] The preparation methods of other compounds are the same as above, which will not be described one by one here. The mass spectra or molecular formulas of other embodiments are shown in Table 1 below:

[0171] Table 1

[0172]

[0173] The present invention also provides an organic electroluminescent device, which is made of the organic electroluminescent material, more specifically, made of the organic electroluminescent material of the compound of chemical formula I.

[0174] The compound of formula I of the present invention is used as a doping material in a light-emitting layer, specifically as a phosphorescent doping material.

[0175] The present invention also provides a display panel, comprising a substrate, a first electrode, a hole injection layer, a hole transport layer, an electron blocking layer, an organic electroluminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a second electrode arranged in sequence.

[0176] Generally speaking, an organic electroluminescent device includes a first electrode, a second electrode, and an organic material layer between the electrodes. The organic material can be divided into multiple regions. For example, the organic material layer can include a hole transport region, a light emitting layer, and an electron transport region.

[0177] In a specific embodiment, a substrate may be used below the first electrode or above the second electrode. The substrate is a glass or polymer material with excellent mechanical strength, thermal stability, water resistance, and transparency. In addition, a thin film transistor (TFT) may also be provided on the substrate used as a display.

[0178] The first electrode can be formed by sputtering or depositing a material used as the first electrode on a substrate. When the first electrode is used as an anode, transparent conductive oxide materials such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO) and any combination thereof can be used. In addition, the anode material can also be selected from materials and combinations thereof that facilitate hole injection other than the listed anode materials, including materials known to be suitable for anodes. 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) and any combination thereof can be used. In addition to the cathode materials listed above, the cathode material can also be a material and a combination thereof that facilitates electron injection, including materials known to be suitable for cathodes.

[0179] The organic material layer can be formed on the electrode by vacuum thermal evaporation, spin coating, printing and the like. The compound used as the organic material layer can be an organic small molecule, an organic macromolecule and a polymer, and a combination thereof. The hole transport region is located between the anode and the light-emitting layer. The hole transport region can be a hole transport layer (HTL) of a single-layer structure, including a single-layer hole transport layer containing only one compound and a single-layer hole transport layer containing multiple compounds. The hole transport region can also be a multilayer structure including at least one layer of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL).

[0180] The hole injection layer is located between the anode and the hole transport layer. The hole injection layer can be a single compound material or a combination of multiple compounds. For example, the hole injection layer can use one or more compounds from HT-1 to HT-34 (as shown below), or one or more compounds from HI-1 to HI-3 below; or one or more compounds from HT-1 to HT-34 can be doped with one or more compounds from HI-1 to HI-3 below, but it is not limited to the above materials.

[0181] .

[0182] The material of the hole transport layer can be selected from but not limited to phthalocyanine derivatives such as CuPc, conductive polymers or polymers containing conductive dopants such as polyphenylene ethylene, 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 in HT-1 to HT-34 below; or any combination thereof.

[0183]

[0184] .

[0185] The light-emitting layer includes a light-emitting dye (i.e., dopant) that can emit different wavelength spectra, and may also include a host material (Host). The light-emitting layer can be a monochrome light-emitting layer that emits a single color such as red, green, and blue. A plurality of monochrome light-emitting layers of different colors can be arranged in a plane according to a pixel pattern, or they can be stacked together to form a color light-emitting layer. When light-emitting layers of different colors are stacked together, they can be separated from each other or connected to each other. The light-emitting layer can also be a single color light-emitting layer that can simultaneously emit different colors such as red and green.

[0186] According to different technologies, the luminescent layer material can be phosphorescent electroluminescent materials, thermally activated delayed fluorescent luminescent materials and other materials. In an OLED device, a single luminescent technology can be used, or a combination of multiple different luminescent technologies can be used. These different luminescent materials classified by technology can emit light of the same color or different colors. Formula I of the present invention is used as a doping material in the luminescent layer.

[0187] The OLED organic material layer may further include an electron transport region between the light emitting layer and the cathode. The electron transport region may be an electron transport layer (ETL) of a single-layer 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 may also be a multi-layer structure including at least one layer of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL).

[0188] In the present invention, the electron transport layer material can be selected from but not limited to one or more combinations of ET-1 to ET-57 listed below:

[0189]

[0190] .

[0191] The device also includes an electron injection layer located between the electron transport layer and the cathode. The electron injection layer material includes but is not limited to one or more combinations of the following: LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, Ca.

[0192] In order to further describe the present invention, more specific device embodiments are listed below.

[0193] Device Example 1

[0194] All example devices were passed through a high vacuum (<10 -7The anode electrode was 1200 Å indium tin oxide (ITO). The cathode consisted of 10 Å Liq (8-hydroxyquinoline lithium) followed by 1000 Å Al. All devices were packaged with epoxy-sealed glass lids in a nitrogen glove box (H2O and O2 <1 ppm) immediately after fabrication, and a dehumidifier was incorporated inside the package. The organic stack of the device example is composed of the following in sequence: ITO surface, 100Å of HT-13 as a hole injection layer (HIL); 400Å of HT-13 as a hole transport layer (HTL); 50Å of EBM as an electron blocking layer (EBL); the light-emitting layer red host material RH-01 and the phosphorescent dopant material compound I-1 are mixed and evaporated at a rate ratio of 97:3 to form an light-emitting layer (EML), and the light-emitting layer has a thickness of 400Å; 350Å of Liq (8-hydroxyquinoline lithium) doped with 35% ET-13 as an electron transport layer (ETL) is evaporated thereon.

[0195] Table 2 shows the materials and thicknesses of the device layers.

[0196] Table 2 Device layer materials and thickness

[0197]

[0198] Device Example 2-Device Example 18

[0199] An organic electroluminescent device was prepared by the same method as in Device Example 1, with the only difference being that the doping material Ⅰ-1 was replaced by Ⅰ-3, Ⅰ-6, Ⅰ-13, Ⅰ-15, Ⅰ-31, Ⅰ-41, Ⅰ-58, Ⅰ-69, ​​Ⅰ-70, Ⅰ-72, Ⅰ-80, Ⅰ-97, Ⅰ-99, Ⅰ-103, Ⅰ-105, Ⅰ-116 and Ⅰ-120, respectively.

[0200] Device Comparison Examples 1-8

[0201] An organic electroluminescent device was prepared in the same manner as in Device Example 1, except that the compound of the structure of Comparative Example 1-8 was used instead of the compound of doping compound I-1 in Example 1.

[0202] The structures of EBM, RH-01 and Comparative Examples 1-8 are as follows:

[0203]

[0204]

[0205]

[0206]

[0207] .

[0208] The driving voltage, luminous efficiency and life of the organic electroluminescent devices obtained in the above device embodiments and device comparative examples were characterized at a brightness of 6000 (nits). The test results are shown in Table 3 below:

[0209] Table 3

[0210]

[0211] It can be seen from Table 3 that, compared with the organic electroluminescent device prepared by using the compound provided by the present invention as the doping material of the light-emitting layer, the present invention selects a specific ligand compound, and by replacing the 3-position of dibenzothiophene with a specific substituent, it is possible to change the spatial configuration and stereostructure between molecules, set the molecular orientation, and have special device performances of increasing the turn-on voltage and low driving voltage, improve the crosstalk phenomenon between sub-pixels, and enable the OLED device to have the advantages of long life, high efficiency, and low driving voltage.

[0212] The above embodiments only list the effect data of devices made of a part of the structural formulas. This is a representative sampling test. According to the experimental data, the overall data is not much different and can represent the effects of other unlisted structures.

[0213] Formula I-3 of the present invention replaces substituents at both the 3-position and 4-position of dibenzothiophene, while comparative example 5 replaces only at the 4-position. The start-up voltage is increased by 0.1V, and the driving voltage is reduced by 0.2V. The efficiency is increased by about 24% and the life is increased by 300h, achieving a significant improvement in performance.

[0214] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic electroluminescent material, characterized in that: The structure of the organic electroluminescent material is shown in Formula I: ； in, R is selected from -D, -F, -CN, -CF3, -CH2F, -CHF2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, terphenyl, fluorenyl, phenanthrenyl, triphenylene or any one of the following substituents: ； R1 is hydrogen, methyl, ethyl, -F, -CN, -CF3 or any one of the following substituents: ； R2 and R3 are independently selected from -H or -D; R4-R 11 Independently selected from any one of -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, phenanthrenyl, anthracenyl, and triphenylene.

2. The organic electroluminescent material according to claim 1, characterized in that: R is selected from methyl, ethyl, -F, -CN, -CF3 or any one of the following substituents: 。 3. An organic electroluminescent material, characterized in that: The structure of the organic electroluminescent material includes but is not limited to any one of the following compounds: 。 4. A method for preparing an organic electroluminescent material as claimed in claim 1, characterized in that: The method operates as follows: (1) Under nitrogen protection, a ligand compound of formula LA and IrC13·3H2O are placed in a reaction system, a mixed solution of ethylene glycol ethyl ether and purified water is added, and the mixture is refluxed under nitrogen protection, and then cooled to room temperature. A precipitate is precipitated, and the precipitate is filtered, washed and dried with water, anhydrous ethanol, and petroleum ether in sequence to obtain a bridging ligand compound represented by intermediate formula II; (2) Weigh the intermediate compound of formula II and anhydrous potassium carbonate, add ethylene glycol ethyl ether, and then add the ligand compound of formula LB, reflux under nitrogen protection, filter, wash with alcohol, and dry; use dichloromethane as solvent, use silica gel column chromatography, concentrate the filtrate to precipitate solid, and obtain compound of formula I; The specific synthetic route is as follows: ; Among them, R, R1-R 11 The selected groups are as defined in claim 1.

5. An application of an organic electroluminescent material, characterized in that: The organic electroluminescent material according to any one of claims 1 to 3 is applied to an organic electroluminescent device.

6. The use according to claim 5, characterized in that: The organic electroluminescent device comprises an organic layer; the organic layer contains the organic electroluminescent material.

7. The use according to claim 6, characterized in that: The organic electroluminescent material is used as a doping material in the light-emitting layer.

Images