MR-TADF-phosphorescence self-sensitization system luminescent material based on energy transfer optimization

Abstract

An MR-TADF-phosphorescence self-sensitization system luminescent material based on energy transfer optimization is characterized in that MR-TADF molecules and iridium and platinum complex phosphorescence molecules are covalently bonded in a manner of breaking conjugation through a large torsion angle close to 90 degrees, and the MR-TADF-phosphorescence self-sensitization system luminescent material has high # imgabs0 # resonance energy transfer rate, full inhibition of Dexter energy transfer and high up-conversion efficiency; according to the invention, the resonance energy transfer rate of the # imgabs2 # is improved, the energy transfer of Dexter is inhibited, the energy transfer between the # imgabs2 # and the Dexter is optimized, the triplet state exciton density of a luminescent layer is reduced, and the problem of efficiency roll-off of a phosphorescent OLED (Organic Light Emitting Diode) under high brightness is solved.

Description

Technical Field

[0001] The invention relates to the technical field of organic electroluminescence, and in particular to a luminescent material of a MR-TADF-phosphorescence self-sensitization system based on energy transfer optimization. Background Art

[0002] Organic light-emitting diode (OLED) has become the most competitive light source technology with its advantages of self-luminescence, light weight, flexibility, rich luminous colors, high electroluminescent efficiency and low-cost preparation (solution method). Phosphorescent OLED display screens have occupied a major market share in the display of mobile phones, tablets and computers, creating huge economic value (usually brightness <500cdm -2 However, for lighting, micro-projectors, virtual reality, augmented reality and biomedical devices with high brightness requirements (usually brightness > 5000cdm -2 ) field, serious efficiency roll-off (the phenomenon that the device electroluminescent efficiency decreases with increasing current density) is a common problem of phosphorescent OLEDs at high brightness. The accumulation of long-lived triplet excitons at high brightness (triplet-triplet annihilation, etc.) is the main reason for this phenomenon; it not only increases energy consumption, but also significantly shortens the life of the device, and has become a bottleneck for the further development of phosphorescent OLEDs.

[0003] In order to overcome this difficulty, strategies such as expanding the binding area of ​​holes and electrons, reducing the lifetime of triplet excitons, and inhibiting molecular aggregation have been tried. However, one of the most effective strategies is to use thermally activated delayed fluorescence (TADF) sensitizers to sensitize phosphorescent materials. TADF molecules can upconvert triplet (T1) excitons to singlet (S1) excitons at room temperature, and then through long-range Energy transfer sensitized phosphorescent materials can not only reduce the concentration of triplet excitons in the light-emitting layer, but also improve the utilization efficiency of excitons in the light-emitting layer, showing great potential in reducing device efficiency roll-off. The energy transfer rate is conducive to suppressing the efficiency roll-off of the device, while Dexter energy transfer triggers the efficiency roll-off. The current TADF-sensitized phosphorescence strategy mainly adopts a binary system of TADF host doped with phosphorescent materials or a ternary system of common host doped with auxiliary TADF host and phosphorescent materials. For example, the patent application with publication number US10566542B2 discloses an organic electroluminescent device, in which the host material of the light-emitting layer includes a thermally activated delayed fluorescent material, the host material is doped with a dye, and the dye includes at least one phosphorescent dye. However, this strategy has the following problems: (1) The large intermolecular distance between the TADF host and the phosphorescent material causes The energy transfer rate is low; (2) the high TADF doping concentration makes it difficult to suppress Dexter energy transfer. Summary of the invention

[0004] In view of the shortcomings of the current TADF-sensitized phosphorescence strategy in suppressing the serious efficiency roll-off at high brightness of phosphorescent OLEDs, the purpose of the present invention is to provide a MR-TADF-phosphorescence self-sensitized system luminescent material based on energy transfer optimization, which covalently bonds the MR-TADF molecules to the iridium and platinum complex phosphorescent molecules by interrupting the conjugation with a large torsion angle (close to 90°), thereby improving the efficiency of the luminescent material by shortening the energy transfer distance. The energy transfer rate is improved by suppressing Dexter energy transfer through a large twist angle, thereby improving the upconversion efficiency and reducing the triplet exciton density in the device light-emitting layer. The MR-TADF-phosphorescent self-sensitized system luminescent material with high resonant energy transfer rate, fully suppressed Dexter energy transfer and high upconversion efficiency solves the problem of severe efficiency roll-off under high brightness of phosphorescent OLEDs.

[0005] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A MR-TADF-phosphorescence self-sensitization system luminescent material based on energy transfer optimization has a covalent bond formed between the MR-TADF molecules and the iridium and platinum complex phosphorescent molecules by interrupting the conjugation at a large torsion angle close to 90°.

[0007] The MR-TADF-phosphorescence self-sensitization system luminescent material has a general chemical formula:

[0008]

[0009] Wherein, Ar1 is selected from any of the following structures:

[0010]

[0011] Ar2 is selected from any of the following structures; R1 is any substituent selected from hydrogen atom, fluorine atom, methyl, methoxy, isopropyl or tert-butyl:

[0012]

[0013] BN is selected from any of the following structures, and the substitution position and number of the BN structure on Ar1 or Ar2 can be varied; R2 is any substituent selected from tert-butyl, carbazole, acridine, phenothiazine, phenoxazine or diphenylamine; R3 is any substituent selected from hydrogen, methyl, methoxy or isopropyl:

[0014]

[0015] O^X is an acetylacetone or pyridine carboxylic acid auxiliary ligand, X is an oxygen and nitrogen atom, and is selected from any of the following structures:

[0016]

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) Covalent bonding of MR-TADF and phosphorescent materials can greatly shorten the distance between them and significantly increase Energy transfer rate, high The resonant energy transfer rate can quickly transfer the singlet exciton energy of the MR-TADF sensitizer unit to the phosphorescent center, reduce the number of cyclic conversions between the MR-TADF sensitizer unit S1 and T1, improve its T1→S1 upconversion efficiency, and reduce the triplet exciton density of the light-emitting layer.

[0019] (2) The twist angle close to 90° can effectively prevent the overlap of the frontier orbitals of the two, thereby fully inhibiting the Dexter energy transfer process, blocking the competitive channel of Dexter energy transfer for T1, improving the upconversion efficiency of the MR-TADF sensitization unit T1→S1, and reducing the triplet exciton density of the light-emitting layer. The resonant energy transfer rate and the suppression of Dexter energy transfer double the advantages of this type of MR-TADF-phosphorescent self-sensitized luminescent material to suppress the severe efficiency roll-off at high brightness of phosphorescent OLEDs.

[0020] In summary, the present invention breaks the conjugation by a large torsion angle close to 90°, covalently bonds the MR-TADF molecule to the phosphorescent molecules of iridium and platinum complexes, and develops a series of high MR-TADF-phosphorescent self-sensitized system luminescent materials with high resonant energy transfer rate, fully suppressed Dexter energy transfer and high upconversion efficiency have important practical value for practical applications in the fields of phosphorescent OLED lighting, micro-projectors, virtual reality, augmented reality and biomedical devices with high brightness requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrTT4BN prepared in Example 1 of the present invention in a toluene solution.

[0022] Figure 2 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrBT4BN prepared in Example 2 of the present invention in a toluene solution.

[0023] Figure 3 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrIQTT4BN prepared in Example 3 of the present invention in a toluene solution.

[0024] Figure 4 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrIQBT4BN prepared in Example 4 of the present invention in a toluene solution.

[0025] Figure 5 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrIQPh4BN prepared in Example 5 of the present invention in a toluene solution.

[0026] Figure 6 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrIQCzFl4BN prepared in Example 6 of the present invention in a toluene solution.

[0027] Figure 7 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrTT5BN prepared in Example 7 of the present invention in a toluene solution.

[0028] Figure 8 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrBT5BN prepared in Example 8 of the present invention in a toluene solution.

[0029] Fig. 9 This is a room temperature ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material PtIQCzFl4BN prepared in Example 9 of the present invention in a toluene solution.

[0030] Fig.10 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrTT4BN prepared in Example 1 of the present invention in a toluene solution.

[0031] Fig.11 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrBT4BN prepared in Example 2 of the present invention in a toluene solution.

[0032] Fig.12 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitized system luminescent material IrIQTT4BN prepared in Example 3 of the present invention in a toluene solution.

[0033] Fig.13 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrIQBT4BN prepared in Example 4 of the present invention in a toluene solution.

[0034] Fig.14 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrIQPh4BN prepared in Example 5 of the present invention in a toluene solution.

[0035] Fig.15 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitized system luminescent material IrIQCzFl4BN prepared in Example 6 of the present invention in a toluene solution.

[0036] Fig.16 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitized system luminescent material IrTT5BN prepared in Example 7 of the present invention in a toluene solution.

[0037] Fig.17 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrBT5BN prepared in Example 8 of the present invention in a toluene solution.

[0038] Fig.18 This is a room temperature photoluminescence spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material PtIQCzFl4BN prepared in Example 9 of the present invention in a toluene solution. DETAILED DESCRIPTION

[0039] Embodiment 1

[0040] MR-TADF-phosphorescent self-sensitized system luminescent material IrTT4BN, chemical formula: C 119 H 113 B2IrN6O2S4, molecular structure formula is:

[0041]

[0042] The specific operation process is as follows:

[0043] Step 1: Synthesis of organic ligands containing MR-TADF sensitizing units

[0044]

[0045] (1) 5.00 g of 2-bromo-1,3-difluorobenzene (25.91 mmol) and 15.93 g of 3,6-di-tert-butylcarbazole (57.00 mmol) were weighed into a SCHLENK reaction tube. 150 mL of anhydrous DMF was added under N2 atmosphere, and the mixture was stirred at 150°C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was slowly dripped into stirred saturated brine, and a solid was obtained by filtration. The obtained solid was separated and purified by silica gel column chromatography with a mobile phase of petroleum ether / dichloromethane = 10 / 1, and 15.91 g of Br-tCzPh was finally obtained as a white solid with a yield of 86.3%.

[0046] 1 H NMR (400MHz, CDCl3, δ): 8.16 (d, J=2.0Hz, 4H), 7.67 (dd, J=8.8, 5.4Hz, 1H), 7.61 ( d,J=8.0Hz,2H),7.51(dd,J=8.4,2.0Hz,4H),7.11(d,J=8.4Hz,4H),1.47(s,36H).

[0047]

[0048] (2) Weigh 3.56 g Br-tCzPh (5.00 mmol) into a SCHLENK reaction tube, add 70 mL mesitylene under N2 atmosphere. Then slowly add 2.20 mL n-BuLi (concentration 2.5 M) (5.50 mmol) dropwise under ice bath, react for 20 min under ice bath, and stir at room temperature for 1 h; then cool the reaction to -40 °C, add 0.95 mL pure BBr3 (10.00 mmol), react at this temperature for 15 min, then naturally warm to room temperature and stir for 0.5 h; place the reaction under ice bath, add 1.60 mL N,N-diisopropylethylamine (10 mmol); finally, place the reaction at 180 °C and stir for 16 h. After the reaction was completed, the mixture was cooled to room temperature, ice water was added to quench the reaction, the reaction solution was diluted with saturated saline, extracted with dichloromethane three times, the organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was removed by distillation under reduced pressure. The residual solid was separated and purified by silica gel column chromatography with a mobile phase of petroleum ether / dichloromethane = 7 / 1. Finally, tCzBN was obtained as a yellow solid of 2.01 g with a yield of 62.7%.

[0049] 1 H NMR (400MHz, CDCl3, δ): 9.14 (d, J = 2.0Hz, 2H), 8.47 (d, J = 2.0Hz, 2H), 8.41 (d, J = 8.8Hz, 2H), 8.34 (d, J = 8.0Hz ,2H),8.27(d,J=2.0Hz,2H),8.03(t,J=8.4Hz,1H),7.66(dd,J=8.8,2.0Hz,2H),1.67(s,18H),1.53(s,18H).

[0050]

[0051] (3) 4.00 g tCzBN (6.24 mmol), 2.38 g pinacol borate (9.36 mmol), 0.04 g methoxy(cyclooctadiene)iridium dimer (0.06 mmol), and 0.03 g 4,4'-di-tert-butyl-2,2'-bipyridine (0.12 mmol) were weighed into a SCHLENK reaction tube. Under a N2 atmosphere, 80 mL of THF was added, and the reaction was refluxed and stirred for 16 h. After the reaction system was cooled to room temperature, the solvent was removed by distillation under reduced pressure, and the residual solid was separated and purified by silica gel column chromatography with the mobile phase being petroleum ether / dichloromethane = 4 / 1. Finally, 4.17 g of tCzBN-Bpin was obtained as a yellow solid with a yield of 88.2%.

[0052] 1H NMR (400MHz, CDCl3, δ): 9.14 (d, J = 2.0Hz, 2H), 8.79 (s, 2H), 8.54 (d, J = 8.4Hz, 2H), 8.48 (d, J = 1.6Hz ,2H),8.27(d,J=2.0Hz,2H),7.74(dd,J=8.8,2.0Hz,2H),1.68(s,18H),1.55(s,18H),1.50(s,12H).

[0053]

[0054] (4) Weigh 5.00 g of 2,4-dibromopyridine (21.11 mmol), 4.66 g of thiophene [3,2-B] thiophene-2-boronic acid (25.33 mmol) and 0.24 g of Pd (PPh 3) 4 (0.21 mmol) in a SCHLENK reaction tube. Under N 2 atmosphere, add 80 mL of THF and 30 mL of 2M K 2 CO 3 aqueous solution. Stir the reaction at 60 ° C for 16 h. After the reaction is completed, the reaction solution is diluted with saturated brine, extracted with dichloromethane three times, the organic phases are combined, and the solvent is removed by vacuum distillation. The residual solid is separated and purified by silica gel column chromatography with a mobile phase of petroleum ether / dichloromethane = 2 / 1. Finally, PyTT 4 Br is obtained as a white solid of 4.53 g with a yield of 72.5%.

[0055] 1 H NMR (400MHz, CDCl3, δ): 8.38 (d, J = 5.2Hz, 1H), 7.84 (d, J = 2.0Hz, 1H), 7.78 (s, 1H) ,7.45(d,J=5.2Hz,1H),7.32(dd,J=5.6,1.6Hz,1H),7.29(dd,J=5.2,0.8Hz,1H).

[0056]

[0057] (5) Weigh 0.20g PyTT4Br (0.68mmol), 0.57g tCzBN-BPin (0.74mmol) and 23.4mg Pd(PPh3)4 (0.02mmol) in a SCHLENK reaction tube, add 20mL THF and 8mL 2MK2CO3 aqueous solution under N2 atmosphere. Stir the reaction at 100℃ for 16h; after the reaction is completed, dilute the reaction solution with saturated brine, extract with dichloromethane three times, combine the organic phases, remove the solvent by vacuum distillation, and separate and purify the residual solid by silica gel column chromatography, with the mobile phase being petroleum ether / dichloromethane = 2 / 1. Finally, 0.31g of L-TT4BN was obtained as a yellow solid with a yield of 54.3%.

[0058] 1 H NMR (400MHz, CDCl3, δ): 9.11 (d, J = 2.0Hz, 2H), 8.79 (d, J = 5.2Hz, 1H), 8.50 (s ,2H),8.48(d,J=2.0Hz,2H),8.39(d,J=8.8Hz,2H),8.27(d,J=2.0Hz,2H),8.1 0(s,1H),7.97(s,1H),7.70(dd,J=8.8,2.0Hz,2H),7.65(dd,J=5.2,1.6Hz,1 H),7.47(d,J=5.2Hz,1H),7.36(d,J=5.2Hz,1H),1.68(s,18H),1.54(s,18H).

[0059] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrTT4BN

[0060]

[0061] 0.20 g L-TT4BN (0.23 mmol) and 37.4 mg iridium trichloride (0.12 mmol) were weighed into a SCHLENK reaction tube. Under a N2 atmosphere, 60 mL of a mixed solvent of THF and water (v / v, 3 / 1) was added, and the reaction was stirred at 110°C for 16 h. After the reaction system was cooled to room temperature, it was extracted with dichloromethane three times, the organic phases were combined and dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation under reduced pressure. The residue was redissolved in 20 mL of dry dichloromethane solution. At the same time, 17.8 mg Na(acac) (0.15 mmol) was dissolved in 4 mL of methanol and then dropped into the above dichloromethane reaction solution, and stirred at room temperature for 2 h. After the reaction was completed, the reaction solution was used to remove the solvent using a rotary evaporator, and the residual solid was separated and purified by thin layer chromatography, with the developing solvent being petroleum ether / dichloromethane = 3 / 2. Finally, 82.3 mg of a red solid was obtained with a yield of 35.2%.

[0062] 1H NMR (400MHz, CDCl3, δ): 9.19 (d, J = 2.0Hz, 4H), 8.76 (s, 4H), 8.70 (d, J = 6.0Hz, 2H), 8.56(d,J=8.8Hz,4H),8.53(d,J=2.0Hz,4H),8.33(d,J=2.4Hz,4H),8.07(d,J=2.0 Hz,2H),7.79(dd,J=8.8,2.0Hz,4H),7.65(dd,J=6.0,2.0Hz,2H),7.24(d,J=5.2Hz ,2H),7.13(d,J=5.2Hz,2H),5.49(s,1H),2.02(s,6H),1.71(s,36H),1.57(s,36H).

[0063] Figure 1 The ultraviolet absorption spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrTT4BN in toluene solution finally synthesized in this embodiment shows that the energy of the characteristic absorption band of the MR-TADF unit at 482nm is higher than the MLCT absorption band of the iridium complex unit at 520-600nm, which provides a basis for the MR-TADF unit to transfer energy forward to the iridium complex unit. Fig.10 The photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrTT4BN in toluene solution finally synthesized in this example shows that IrTT4BN only shows the emission peak of the iridium complex unit (630nm), and the emission peak of the MR-TADF unit (around 490nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0064] Embodiment 2

[0065] MR-TADF-phosphorescent self-sensitized system luminescent material IrBT4BN, chemical formula: C 123 H 117 B2IrN6O2S2, molecular structure formula is:

[0066]

[0067] The specific operation process is as follows:

[0068] Step 1: Synthesis of organic ligands containing MR-TADF sensitizing units

[0069] The organic ligand containing the MR-TADF sensitizing unit required to be synthesized in this example shares the same MR-TADF boric acid pinacol ester tCzBN-Bpin containing boron and nitrogen atoms as that in Example 1. Since its detailed synthesis steps have been listed in step 1 (1), (2) and (3) in Example 1, steps 1 (1), (2) and (3) in the specific operation process of this example are omitted here, and step 1 (4) in the operation process is directly listed. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above steps 1 (1), (2) and (3).

[0070]

[0071] (4) The synthesis step of PyBT4Br in step 1 of this example is similar to step 1 (4) in Example 1, so the synthesis method of step 1 (4) in Example 1 can be referred to. Therefore, step 1 (4) in the specific operation process of this example will not be described in detail here.

[0072] PyBT4Br, white solid, yield 78.8%. 1 H NMR (400MHz, CDCl3, δ): 8.44 (d, J = 5.6 Hz, 1H), 7.97 (d, J = 1.6 Hz, 1H), 7.88–7.86 (m, 1H), 7.85 (s, 1H), 7.83–7.80 (m, 1H), 7.39–7.35 (m,

[0073] (5) The synthesis step of L-BT4BN in step 1 of this example is similar to step 1 (5) in Example 1, so the synthesis method of step 1 (5) in Example 1 can be referred to. Therefore, step 1 (5) in the specific operation process of this example will not be described in detail here.

[0074] L-BT4BN, yellow solid, yield 57.4%. 1 H NMR (400MHz, CDCl3, δ): 9.08 (d, J = 2.0 Hz, 2H), 8.82 (d, J = 4.8 Hz, 1H), 8.47–8. 46(m,4H),8.36(d,J=8.8Hz,2H),8.26(d,J=2.0Hz,2H),8.19(s,1H),8.01(s,1 H),7.94(dd,J=6.0,3.6Hz,1H),7.88–7.86(m,1H),7.69(dd,J=8.8,2.0Hz,2H ),7.65(dd,J=4.8,1.6Hz,1H),7.41–7.39(m,2H),1.68(s,18H),1.54(s,18H).

[0075] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrBT4BN

[0076]

[0077] The synthesis step of IrBT4BN in step 2 of this example is similar to step 2 in Example 1, so the synthesis method of step 2 in Example 1 can be referred to, so step 2 in the specific operation process of this example is not described in detail here. The developing solvent in this example is dichloromethane / petroleum ether = 3 / 2, and the yield is 37.6%. The obtained MR-TADF-phosphorescence self-sensitization system luminescent material IrBT4BN is a red solid.

[0078] 1 H NMR (400MHz, CDCl3, δ): 9.19 (d, J = 2.0 Hz, 4H), 8.77 (s, 4H), 8.75 (d, J = 6.0 Hz, 2H), 8.58 (s, 2H) ,8.56(s,2H),8.64(d,J=1.6Hz,4H),8.34(d,J=2.0Hz,4H),8.21(d,J=2.0Hz,2H),7.81(dd,J=8 .8,2.0Hz,4H),7.77(d,J=8.0Hz,2H),7.65(dd,J=6.0,2.0Hz,2H),7.15(t,J=7.6Hz,2H),6.98 (t,J=7.6Hz,2H),6.58(d,J=8.0Hz,2H),5.47(s,1H),1.98(s,6H),1.71(s,36H),1.57(s,36H).

[0079] Figure 2 The ultraviolet absorption spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrBT4BN in toluene solution finally synthesized in this embodiment shows that the characteristic absorption band energy of the MR-TADF unit at 484nm is higher than the MLCT absorption band of the iridium complex unit at 520-600nm, which provides a basis for the MR-TADF unit to transfer energy forward to the iridium complex unit. Fig.11 The photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrBT4BN in toluene solution finally synthesized in this example shows that IrBT4BN only shows the emission peak of the iridium complex unit (650nm), and the emission peak of the MR-TADF unit (around 490nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0080] Embodiment 3

[0081] MR-TADF-phosphorescent self-sensitized system luminescent material IrIQTT4BN, chemical formula: C 127 H 117 B2IrN6O2S4, molecular structure formula is:

[0082]

[0083] The specific operation process is as follows:

[0084] Step 1: Synthesis of organic ligands containing MR-TADF sensitizing units

[0085] The organic ligand containing the MR-TADF sensitizing unit required to be synthesized in this example shares the same MR-TADF boric acid pinacol ester tCzBN-Bpin containing boron and nitrogen atoms as that in Example 1. Since its detailed synthesis steps have been listed in step 1 (1), (2) and (3) in Example 1, steps 1 (1), (2) and (3) in the specific operation process of this example are omitted here, and step 1 (4) in the operation process is directly listed. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above steps 1 (1), (2) and (3).

[0086]

[0087] (4) Weigh 3.00 g 1,4-dichloroisoquinoline (15.15 mmol), 3.35 g thiophene [3,2-B] thiophene-2-boronic acid (18.18 mmol), 6.28 g K2CO3 (45.44 mmol) and 0.53 g Pd(PPh3)2Cl2 (0.76 mmol) in a SCHLENK reaction tube. Add 100 mL of a mixed solvent of THF and water (v / v, 4 / 1) under N2 atmosphere. Stir the reaction at 65°C for 16 h. After the reaction is completed, dilute the reaction solution with saturated brine, extract with dichloromethane three times, combine the organic phases, remove the solvent by vacuum distillation, and separate and purify the residual solid by silica gel column chromatography with a mobile phase of petroleum ether / dichloromethane = 1 / 1. Finally, 3.78 g of IQTT4Cl was obtained as a white solid with a yield of 82.7%.

[0088] 1 H NMR (400MHz, CDCl3, δ): 8.62 (s, 1H), 8.61 (d, J = 8.4Hz, 1H), 8.30 (d, J = 8.4Hz, 1H), 7.86 (td, J = 6.8, 0.8Hz,1H),7.78(s,1H),7.72(td,J=6.8,1.2Hz,1H),7.49(d,J=5.2Hz,1H),7.35(d,J=5.2Hz,1H).

[0089]

[0090] (5) Weigh 0.20 g IQTT4Cl (0.66 mmol), 0.56 g tCzBN-Bpin (0.73 mmol), 0.27 g K2CO3 (1.99 mmol), 7.5 mg Pd(AcO)2 (0.03 mmol) and 31.6 mg X-Phos (0.07 mmol) in a SCHLENK reaction tube. Add 30 mL of a mixed solvent of toluene, ethanol and water (v / v / v, 2 / 1 / 1) under N2 atmosphere. Stir the reaction at 110 °C for 16 h. After the reaction is completed, dilute the reaction solution with saturated brine, extract with dichloromethane three times, combine the organic phases, remove the solvent by vacuum distillation, and separate and purify the residual solid by silica gel column chromatography with a mobile phase of petroleum ether / dichloromethane = 3 / 2. Finally, 0.46 g of L-IQTT4BN was obtained as a yellow solid with a yield of 76.1%.

[0091] 1 H NMR (400MHz, CDCl3, δ): 9.18 (d, J=1.6Hz, 2H), 8.93 (s, 1H), 8.81 (dd, J=6.8, 2.0Hz, 1 H),8.53(s,2H),8.50(d,J=2.0Hz,2H),8.35(dd,J=6.8,2.4Hz,1H),8.31(d,J=8.8Hz, 2H),8.27(d,J=2.0Hz,2H),7.96(d,J=0.8Hz,1H),7.81–7.74(m,2H),7.56(dd,J=8.8, 2.0Hz,2H),7.53(d,J=5.2Hz,1H),7.42(d,J=5.2Hz,1H),1.70(s,18H),1.49(s,18H).

[0092] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrIQTT4BN

[0093]

[0094] The synthesis step of IrIQTT4BN in step 2 of this example is similar to step 2 in Example 1, so the synthesis method of step 2 in Example 1 can be referred to, so step 2 in the specific operation process of this example is not described in detail here. The developing solvent in this example is dichloromethane / petroleum ether = 3 / 2, and the yield is 36.4%. The obtained MR-TADF-phosphorescence self-sensitized system luminescent material IrIQTT4BN is a dark red solid.

[0095] 1H NMR (400MHz, CDCl3, δ): 9.18 (d, J = 1.6 Hz, 4H), 9.03 (dd, J = 7.2, 1.6 Hz, 2H), 8.75 (s, 2H),8.62(s,4H),8.50(d,J=8.0Hz,2H),8.49(d,J=2.0Hz,4H),8.30(d,J=8.8Hz,4H ),8.26(d,J=2.0Hz,4H),7.86–7.79(m,4H),7.49(d,J=8.8Hz,4H),7.31(d,J=5.2Hz ,2H),7.19(d,J=5.2Hz,2H),5.36(s,1H),1.69(s,36H),1.64(s,6H),1.49(s,36H).

[0096] Figure 3 The ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitization system luminescent material IrIQTT4BN in toluene solution finally synthesized in this embodiment shows that the characteristic absorption band energy of the MR-TADF unit at 472nm is higher than the MLCT absorption band of the iridium complex unit at 500-600nm, which provides a basis for the MR-TADF unit to transfer energy forward to the iridium complex unit. Fig.12 The photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrIQTT4BN in toluene solution finally synthesized in this example shows that IrIQTT4BN only shows the emission peak of the iridium complex unit (710nm), and the emission peak of the MR-TADF unit (around 480nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0097] Embodiment 4

[0098] MR-TADF-phosphorescent self-sensitized system luminescent material IrIQBT4BN, chemical formula: C 131 H 121 B2IrN6O2S2, molecular structure formula is:

[0099]

[0100] The specific operation process is as follows:

[0101] Step 1: Synthesis of organic ligands containing MR-TADF sensitizing units

[0102] The organic ligand containing the MR-TADF sensitizing unit required to be synthesized in this example shares the same MR-TADF boric acid pinacol ester tCzBN-Bpin containing boron and nitrogen atoms as that in Example 1. Since its detailed synthesis steps have been listed in step 1 (1), (2) and (3) in Example 1, steps 1 (1), (2) and (3) in the specific operation process of this example are omitted here, and step 1 (4) in the operation process is directly listed. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above steps 1 (1), (2) and (3).

[0103]

[0104] (4) The synthesis step of IrBT4Cl in step 1 of this example is similar to step 1 (4) in Example 3, so the synthesis method of step 1 (4) in Example 3 can be referred to. Therefore, step 1 (4) in the specific operation process of this example will not be described in detail here.

[0105] IQBT4Cl, white solid, yield 63.7%. 1 H NMR (400MHz, CDCl3, δ): 8.66 (s, 1H), 8.33 (d, J = 8.8Hz, 1H), 8.31 (d, J = 8.4Hz, 1H), 7.95–7.9 1(m,1H),7.90–7.85(m,2H),7.81(s,1H),7.73(td,J=6.8Hz,1.6Hz,1H),7.43–7.41(m,2H).

[0106]

[0107] (5) The synthesis step of L-IQBT4BN in step 1 of this example is similar to step 1 (5) in Example 3, so the synthesis method of step 1 (5) in Example 3 can be referred to, so step 1 (5) in the specific operation process of this example is not described in detail here. L-IQBT4BN, yellow solid, yield 77.8%. 1H NMR (400MHz, CDCl3, δ): 9.19 (d, J = 2.0 Hz, 2H), 8.98 (s, 1H), 8.83 (dd, J = 7.6, 2. 0Hz,1H),8.54(s,2H),8.50(d,J=1.6Hz,2H),8.36(dd,J=7.2,2.0Hz,1H),8.31 (d,J=8.8Hz,2H),8.27(d,J=2.0Hz,2H),8.02–7.96(m,3H),7.82–7.76(m,2H), 7.56(dd,J=8.8,2.0Hz,2H),7.47(t,J=8.0Hz,2H),1.70(s,18H),1.50(s,18H).

[0108] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrIQBT4BN

[0109]

[0110] The synthesis step of IrIQBT4BN in step 2 of this example is similar to step 2 in Example 1, so the synthesis method of step 2 in Example 1 can be referred to, so step 2 in the specific operation process of this example is not described in detail here. The developing solvent in this example is dichloromethane / petroleum ether = 3 / 2, and the yield is 38.1%. The obtained MR-TADF-phosphorescence self-sensitization system luminescent material IrIQBT4BN is a brown solid.

[0111] 1 H NMR (400MHz, CDCl3, δ): 9.25 (d, J = 8.4Hz, 2H), 9.16 (d, J = 2.0Hz, 4H), 8.17 (s, 2H), 8.52 (d, J = 8.8H z,2H),8.49(dd,J=8.4,1.6Hz,8H),8.24(d,J=2.0Hz,4H),8.20(d,J=8.8Hz,4H),7.90(t,J=7.2Hz ,2H),7.86(d,J=8.8Hz,2H),7.83(d,J=7.6Hz,2H),7.46(d,J=8.4Hz,4H),7.23(t,J=7.6Hz,2H),6 .99(t,J=7.6Hz,2H),6.66(d,J=8.0Hz,2H),5.34(s,1H),1.68(s,36H),1.58(s,6H),1.49(s,36H).

[0112] Figure 4The ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitized system luminescent material IrIQBT4BN in toluene solution finally synthesized in this embodiment shows that the characteristic absorption band energy of the MR-TADF unit at 472nm is higher than the MLCT absorption band of the iridium complex unit at 500-650nm, which provides a basis for the MR-TADF unit to transfer energy forward to the iridium complex unit. Fig.13 The photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrIQBT4BN in toluene solution finally synthesized in this example shows that IrIQBT4BN only shows the emission peak of the iridium complex unit (730nm), and the emission peak of the MR-TADF unit (around 480nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0113] Embodiment 5

[0114] MR-TADF-phosphorescent self-sensitization system luminescent material IrIQPh4BN, chemical formula: C 127 H 121 B2IrN6O2S2, molecular structure formula is:

[0115]

[0116] The specific operation process is as follows:

[0117] Step 1: Synthesis of organic ligands containing MR-TADF sensitizing units

[0118] The organic ligand containing the MR-TADF sensitizing unit required to be synthesized in this example shares the same MR-TADF boric acid pinacol ester tCzBN-Bpin containing boron and nitrogen atoms as that in Example 1. Since its detailed synthesis steps have been listed in step 1 (1), (2) and (3) in Example 1, steps 1 (1), (2) and (3) in the specific operation process of this example are omitted here, and step 1 (4) in the operation process is directly listed. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above steps 1 (1), (2) and (3).

[0119]

[0120] (4) The synthesis step of IrPh4Cl in step 1 of this example is similar to step 1 (4) in Example 3, so the synthesis method of step 1 (4) in Example 3 can be referred to, so step 1 (4) in the specific operation process of this example is not described in detail here. IQPh4Cl, white solid, yield 60.6%. 1H NMR (400MHz, CDCl3, δ): 8.67 (s, 1H), 8.29 (d, J = 8.8Hz, 1H), 8.12 (d, J = 8.8Hz, 1H), 7.83 (td, J =6.8,1.2Hz,1H),7.67(dd,J=8.0,2.0Hz,2H),7.62(td,J=6.8,1.2Hz,1H),7.57–7.51(m,3H).

[0121]

[0122] (5) The synthesis step of L-IQPh4BN in step 1 of this example is similar to step 1 (5) in Example 3, so the synthesis method of step 1 (5) in Example 3 can be referred to, so step 1 (5) in the specific operation process of this example is not described in detail here. L-IQPh4BN, yellow solid, yield 76.9%. 1 H NMR (400MHz, CDCl3, δ): 9.19 (d, J = 2.0Hz, 2H), 8.96 (s, 1H), 8.55 (s, 2H), 8.50 (d, J = 2.0Hz, 2H), 8.32 (t, J = 8.0Hz, 4H ),8.27(d,J=2.0,2H),7.86(d,J=7.2Hz,2H),7.76(t,J=7.6Hz,1H),7.67–7.55(m,6H),1.70(s,18H),1.50(s,18H).

[0123] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrIQPh4BN

[0124]

[0125] The synthesis step of IrIQPh4BN in step 2 of this example is similar to step 2 in Example 1, so the synthesis method of step 2 in Example 1 can be referred to, so step 2 in the specific operation process of this example is not described in detail here. The developing solvent in this example is dichloromethane / petroleum ether = 1 / 1, and the yield is 35.9%. The obtained MR-TADF-phosphorescence self-sensitization system luminescent material IrIQPh4BN is a red solid.

[0126] 1H NMR (400MHz, CDCl3, δ): 9.18 (d, J = 2.0Hz, 4H), 9.17 (d, J = 7.6Hz, 2H), 8.89 (s, 2H), 8.58 (s, 4H), 8.50(d,J=2.0Hz,4H),8.48(dd,J=8.0,2.0Hz,2H),8.36(d,J=8.8Hz,4H),8.32(d,J=8.8Hz,2H), 8.26(d,J=2.0Hz,4H),7.84–7.77(m,4H),7.58(dd,J=8.8,2.0Hz,4H),7.01(t,J=7.6Hz,2H),6.8 3(t,J=7.6Hz,2H),6.73(d,J=7.6Hz,2H),5.40(s,1H),1.70(s,36H),1.65(s,6H),1.48(s,36H).

[0127] Figure 5 The ultraviolet absorption spectrum of the MR-TADF-phosphorescence self-sensitized system luminescent material IrIQPh4BN in toluene solution finally synthesized in this embodiment shows that the characteristic absorption band energy of the MR-TADF unit at 473nm is higher than the MLCT absorption band of the iridium complex unit at 500-650nm, which provides a basis for the MR-TADF unit to transfer energy positively to the iridium complex unit. Fig.14 This is the photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrIQPh4BN in toluene solution that was finally synthesized in this example. IrIQPh4BN only shows the emission peak of the iridium complex unit (650nm), and the emission peak of the MR-TADF unit (around 480nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0128] Example 6

[0129] MR-TADF-phosphorescent self-sensitized system luminescent material IrIQCzFl4BN, chemical formula: C 185 H 183 B2IrN8O2, molecular structure formula is:

[0130]

[0131] The specific operation process is as follows:

[0132] The organic ligand containing the MR-TADF sensitizing unit required to be synthesized in this example shares the same MR-TADF boric acid pinacol ester tCzBN-Bpin containing boron and nitrogen atoms as that in Example 1. Since its detailed synthesis steps have been listed in step 1 (1), (2) and (3) in Example 1, steps 1 (1), (2) and (3) in the specific operation process of this example are omitted here, and step 1 (4) in the operation process is directly listed. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above steps 1 (1), (2) and (3).

[0133]

[0134] (4) Weigh 4.00 g of 2-bromo-7-iodo-9,9-dimethylfluorene (10.02 mmol), 3.36 g of 3,6-di-tert-butylcarbazole (12.02 mmol), 0.19 g of CuI (1.00 mmol), 0.18 g of 1,10-phenanthroline (1.00 mmol) and 3.37 g of KOH (60.14 mmol) in a SCHLENK reaction tube. Add 100 mL of p-xylene under N2 atmosphere. Stir the reaction at 130°C for 24 h. After the reaction is completed, dilute the reaction solution with saturated brine, extract with dichloromethane three times, combine the organic phases, remove the solvent by vacuum distillation, and separate and purify the residual solid by silica gel column chromatography with petroleum ether / dichloromethane = 10 / 1 as the mobile phase. Finally, 4.07 g of CzFlBr is obtained as a white solid with a yield of 73.7%.

[0135] 1 H NMR (400MHz, CDCl3, δ): 8.16 (d, J = 2.0Hz, 2H), 7.87 (d, J = 8.0Hz, 1H), 7.64 (d, J = 8.0Hz, 1H), 7.61 (t, J = 2.0Hz, 2 H),7.53(td,J=8.4,2.0Hz,2H),7.49(dd,J=8.4,2.0Hz,2H),7.39(d,J=8.4Hz,2H),1.54(s,6H),1.48(s,18H).

[0136]

[0137] (5) Weigh 2.00 g CzFlBr (3.63 mmol), 1.38 g pinacol diboronate (5.45 mmol), 79.7 mg Pd(dppf)Cl2 (0.11 mmol) and 1.07 g potassium acetate (10.90 mmol) in a SCHLENK reaction tube. Add 80 mL 1,4-dioxane under N2 atmosphere. Stir the reaction at 110 °C for 18 h. After the reaction is completed, filter to remove insoluble matter, remove the solvent by vacuum distillation, and separate and purify the residual solid by silica gel column chromatography with a mobile phase of petroleum ether / dichloromethane = 1 / 2. Finally, CzFl-Bpin is obtained as a white solid of 2.77 g with a yield of 88.4%.

[0138] 1 H NMR (400MHz, CDCl3, δ): 8.20 (d, J = 2.0Hz, 2H), 7.95 (d, J = 8.4Hz, 2H), 7.91 (dd, J = 8.0, 1.2Hz, 1H), 7.82, J = 7.6Hz, 1H), 7.66 (d, J = 1. 6Hz, 1H), 7.56 (dd, J=8.0, 2.0Hz, 1H), 7.51 (dd, J=8.8, 2.0Hz, 2H), 7.45 (d, J=8.8Hz, 2H), 1.59 (s, 6H), 1.51 (s, 18H), 1.43 (s, 12H).

[0139]

[0140] (6) The synthesis step of IQCzFl4Cl in step 1 of this example is similar to step 1 (4) in Example 3, so the synthesis method of step 1 (4) in Example 3 can be referred to. Therefore, step 1 (4) in the specific operation process of this example will not be described in detail here.

[0141] IQCzFl4Cl, white solid, yield 82.2%. 1H NMR (400MHz, CDCl3, δ): 8.72 (s, 1H), 8.33 (d, J = 8.8Hz, 1H), 8.23 ​​(d, J = 8.4Hz, 1H), 8.18 (d, J=2.0Hz,2H),7.99(d,J=8.0Hz,1H),7.94(d,J=7.6Hz,1H),7.86(t,J=8.0Hz,1H),7.81(s,1 H),7.71(dd,J=8.0,2.0Hz,1H),7.68(d,J=2.0Hz,1H),7.66(d,J=6.8Hz,1H),7.59(d,J=8.0 ,2.0Hz,1H),7.51(dd,J=8.8,2.0Hz,2H),7.45(d,J=8.8Hz,2H),1.62(s,6H),1.49(s,18H).

[0142]

[0143] (7) The synthesis step of L-IQCzFl4BN in step 1 of this example is similar to step 1 (5) in Example 3, so the synthesis method of step 1 (5) in Example 3 can be referred to, so step 1 (5) in the specific operation process of this example is not described in detail here. L-IQCzFl4BN, yellow solid, yield 75.3%. 1 H NMR (400MHz, CDCl3, δ): 9.20 (d, J = 2.0Hz, 2H), 9.01 (s, 1H), 8.58 (s, 2H), 8.51 (d, J = 2.0Hz, 2H), 8.41 (d, J = 8.4Hz, 1H), 8.38 (d, J = 7 .6Hz,1H),8.36(s,1H),8.34(s,1H),8.28(d,J=2.0Hz,2H),8.18(d,J=1.2Hz,2H),8.04(d,J=2.8Hz,1H),8.02(d,J=2.4Hz,1H),8. 00(d,J=1.2Hz,1H),7.90(dd,J=7.6,1.6Hz,1H),7.79(td,J=7.2,1.2Hz,1H),7.72–7.68(m,2H),7.61(dd,J=8.0,2.0Hz,1H),7.58 (dd,J=8.8,2.4Hz,2H),7.52(dd,J=8.4,1.6Hz,2H),7.47(d,J=8.8Hz,2H),1.71(s,18H),1.68(s,6H),1.51(s,18),1.50(s,18H).

[0144] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrIQCzFl4BN

[0145]

[0146] The synthesis step of IrIQCzFl4BN in step 2 of this example is similar to step 2 in Example 1, so the synthesis method of step 2 in Example 1 can be referred to, so step 2 in the specific operation process of this example is not described in detail here. In this example, the developing solvent is dichloromethane / petroleum ether=2 / 1, and the yield is 37.3%. The obtained MR-TADF-phosphorescence self-sensitization system luminescent material IrIQPh4BN is a brown solid.

[0147] 1 H NMR (400MHz, CDCl3, δ): 9.24 (d, J = 8.4Hz, 2H), 9.20 (d, J = 2.0Hz, 4H), 8.98 (s, 2H), 8.65 (s, 4H), 8.51–8. 48(m,6H),8.43–8.39(m,6H),8.23(d,J=2.0Hz,4H),8.08(d,J=2.0Hz,4H),7.91(t,J=8.0Hz,2H),7.84( d,J=8.0Hz,2H),7.53–7.50(m,6H),7.49(d,J=8.0Hz,2H),7.34(d,J=8.8Hz,4H),7.21–7.18(m,6H),7.1 5(s,2H),5.49(s,1H),1.72(s,6H),1.70(s,36H),1.60(s,6H),1.57(s,6H),1.45(s,36H),1.33(s,36H).

[0148] Figure 6 The ultraviolet absorption spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrIQCzFl4BN in toluene solution finally synthesized in this embodiment shows that the characteristic absorption band energy of the MR-TADF unit at 471nm is higher than the MLCT absorption band of the iridium complex unit at 500-650nm, which provides a basis for the MR-TADF unit to transfer energy positively to the iridium complex unit. Fig.15 This is the photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrIQCzFl4BN in toluene solution that was finally synthesized in this example. IrIQCzFl4BN only shows the emission peak of the iridium complex unit (688nm), and the emission peak of the MR-TADF unit (around 480nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0149] Embodiment 7

[0150] MR-TADF-phosphorescent self-sensitized system luminescent material IrTT5BN, chemical formula: C 171 H 159 B3IrN9S6, molecular structure formula:

[0151]

[0152] The specific operation process is as follows:

[0153] The organic ligand containing the MR-TADF sensitizing unit required to be synthesized in this example shares the same MR-TADF boric acid pinacol ester tCzBN-Bpin containing boron and nitrogen atoms as that in Example 1. Since its detailed synthesis steps have been listed in step 1 (1), (2) and (3) in Example 1, steps 1 (1), (2) and (3) in the specific operation process of this example are omitted here, and step 1 (4) in the operation process is directly listed. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above steps 1 (1), (2) and (3).

[0154]

[0155] (4) Weigh 3.00 g of 5-bromo-2-iodopyridine (10.57 mmol), 2.33 g of thiophene [3,2-B] thiophene-2-boronic acid (12.68 mmol) and 0.37 g of Pd (PPh 3) 4 (0.32 mmol) in a SCHLENK reaction tube. Under N 2 atmosphere, add 80 mL of THF and 30 mL of 2M K 2 CO 3 aqueous solution. Stir the reaction at 90 ° C for 16 h. After the reaction is completed, dilute the reaction solution with saturated brine, extract with dichloromethane three times, combine the organic phases, remove the solvent by vacuum distillation, and separate and purify the residual solid by silica gel column chromatography with petroleum ether / dichloromethane = 2 / 1 as the mobile phase. Finally, 2.77 g of PyTT5Br is obtained as a white solid with a yield of 88.4%. 1 H NMR (400MHz, CDCl3, δ): 8.62 (d, J=2.0Hz, 1H), 7.81 (dd, J=8.8, 2.4Hz, 1H), 7.76 (s, 1H), 7.56 (dd, J=8.8, 0.8Hz, 1H), 7.44 (d, J=5.2Hz, 1H), 7.28 (dd, J=5.2, 0.8Hz, 1H).

[0156]

[0157] (5) The synthesis step of L-TT5BN in step 1 of this example is similar to step 1 (5) in Example 1, so the synthesis method of step 1 (5) in Example 1 can be referred to, so step 1 (5) in the specific operation process of this example is not described in detail here. L-TT5BN, yellow solid, yield 61.4%. 1 H NMR (400MHz, CDCl3, δ): 9.23 (d, J = 2.4Hz, 1H), 9.13 (d, J = 2.0Hz, 2H), 8.53 (s, 2 H),8.48(d,J=1.6Hz,2H),8.43(d,J=8.8Hz,2H),8.27(d,J=2.0Hz,2H),8.24(dd ,J=8.4,2.4Hz,1H),7.92(d,J=8.4Hz,1H),7.91(s,1H),7.68(dd,J=8.8,2.0Hz ,2H),7.48(d,J=5.2Hz,1H),7.36(d,J=5.6Hz,1H),1.68(s,18H),1.54(s,18H).

[0158] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrTT5BN

[0159]

[0160] Weigh 0.20g L-TT5BN (0.23mmol), 37.4mg iridium trichloride (0.12mmol) in a SCHLENK reaction tube, add 60mL of a mixed solvent of THF and water (v / v, 3 / 1) under N2 atmosphere, and stir at 110℃ for 16h. After the reaction system is cooled to room temperature, extract with dichloromethane three times, combine the organic phases and dry with anhydrous sodium sulfate, and remove the solvent by rotary evaporation under reduced pressure. The residue is redissolved in 40mL dry acetone solution, and then 0.10g L-TT5BN (0.12mmol) and 30.0mgCF3SO3Ag (0.12mmol) are added thereto, and the reaction is stirred at 80℃ for 16h. After the reaction is completed, the reaction solution is used to remove the solvent by a rotary evaporator, and the residual solid is separated and purified by thin layer chromatography, and the developing solvent is petroleum ether / dichloromethane = 2 / 1. Finally, 63.1mg of red solid is obtained with a yield of 19.8%.

[0161] 1H NMR (400MHz, CDCl3, δ): 10.95 (d, J = 0.8Hz, 3H), 9.24 (dd, J = 7.2, 2.0Hz, 6H), 8.72 (s, 3H), 8.61 (s, 3H), 8.58 (d, J =8.8Hz,3H),8.52(d,J=2.0Hz,3H),8.38(d,J=1.6Hz,3H),8.02(d,J=2.4Hz,3H),7.86(dd,J=8.8,2.0Hz,3H),7. 83(d,J=2.0Hz,3H),7.64(d,J=8.8Hz,3H),7.04(d,J=8.4Hz,3H),6.99(dd,J=8.8,2.0Hz,3H),6.80(d,J=4.8Hz, 3H),6.61(d,J=4.8Hz,3H),6.37(dd,J=8.4,2.0Hz,3H),1.78(s,27H),1.77(s,27H),1.16(s,27H),0.49(s,27H).

[0162] Figure 7 The ultraviolet absorption spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrTT5BN in toluene solution finally synthesized in this embodiment shows that the characteristic absorption band energy of the MR-TADF unit at 491nm is higher than the MLCT absorption band of the iridium complex unit at 500-570nm, which provides a basis for the MR-TADF unit to transfer energy forward to the iridium complex unit. Fig.16 The photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrTT5BN in toluene solution finally synthesized in this example shows that IrTT5BN only shows the emission peak of the iridium complex unit (644nm), and the emission peak of the MR-TADF unit (around 500nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0163] Embodiment 8

[0164] MR-TADF-phosphorescent self-sensitized system luminescent material IrBT5BN, chemical formula: C 177 H 165 B3IrN9S3, molecular structure formula is:

[0165]

[0166] The specific operation process is as follows:

[0167] Step 1: Synthesis of organic ligand containing MR-TADF sensitizing unit

[0168] The organic ligand containing the MR-TADF sensitizing unit required to be synthesized in this example shares the same MR-TADF boric acid pinacol ester tCzBN-Bpin containing boron and nitrogen atoms as that in Example 1. Since its detailed synthesis steps have been listed in step 1 (1), (2) and (3) in Example 1, steps 1 (1), (2) and (3) in the specific operation process of this example are omitted here, and step 1 (4) in the operation process is directly listed. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above steps 1 (1), (2) and (3).

[0169]

[0170] (4) The synthesis step of PyBT5Br in step 1 of this example is similar to step 1 (4) in Example 7, so the synthesis method of step 1 (4) in Example 7 can be referred to, so step 1 (4) in the specific operation process of this example is not described in detail here. PyBT5Br, white solid, yield 89.6%. 1 H NMR (400MHz, CDCl3, δ): 8.67 (d, J = 2.0Hz, 1H), 7.87–7.79 (m, 4H), 7.68 (d, J = 8.8Hz, 1H), 7.36 (dd, J = 6.0, 3.2Hz, 2H).

[0171]

[0172] (5) The synthesis step of L-BT5BN in step 1 of this example is similar to step 1 (5) in Example 1, so the synthesis method of step 1 (5) in Example 1 can be referred to, so step 1 (5) in the specific operation process of this example is not described in detail here. L-BT5BN, yellow solid, yield 60.5%. 1 H NMR (400MHz, CDCl3, δ): 9.26 (d, J = 2.4Hz, 1H), 9.12 (d, J = 2.0Hz, 2H), 8.51 (s, 2H), 8. 47(d,J=1.6Hz,2H),8.41(d,J=8.8Hz,2H),8.26(d,J=2.0Hz,2H),8.24(dd,J=8.4,2. 4Hz,1H),8.01(d,J=8.0Hz,1H),7.97(s,1H),7.94(dd,J=8.8,3.6Hz,1H),7.89–7.87 (m,1H),7.67(dd,J=8.8,2.0Hz,2H),7.42–7.40(m,2H),1.68(s,18H),1.54(s,18H).

[0173] Step 2: Synthesis of MR-TADF-phosphorescence self-sensitization system luminescent material IrBT5BN

[0174]

[0175] The synthesis step of IrBT5BN in step 2 of this example is similar to step 2 in Example 7, so the synthesis method of step 2 in Example 7 can be referred to, so step 2 in the specific operation process of this example is not described in detail here. The developing solvent in this example is dichloromethane / petroleum ether = 2 / 1, and the yield is 21.5%. The obtained MR-TADF-phosphorescence self-sensitized system luminescent material IrBT5BN is a red solid.

[0176] 1 H NMR (400MHz, CDCl3, δ): 11.13 (d, J = 2.0, 3H), 9.35 (d, J = 2.0 Hz, 6H), 8.73 (s, 3H), 8.70 (s, 3H), 8.64 (d, J = 8.8H z,3H),8.51(d,J=1.6Hz,3H),8.43(d,J=1.6Hz,3H),7.95(dd,J=8.4,2.0Hz,6H),7.88(d,J=2.0Hz,3H),7.75( d,J=7.2Hz,3H),7.17(t,J=8.0Hz,6H),6.94(dd,J=8.8,2.0Hz,3H),6.71(t,J=7.2Hz,3H),6.46(dd,J=8.8,2. 0Hz,3H),6.43(t,J=8.4Hz,3H),5.76(d,J=8.4,3H),1.79(s,27H),1.77(s,27H),1.20(s,27H),0.31(s,27H).

[0177] Figure 8 The ultraviolet absorption spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrBT5BN in toluene solution finally synthesized in this embodiment shows that the energy of the characteristic absorption band of the MR-TADF unit at 492nm is higher than the MLCT absorption band of the iridium complex unit at 530-580nm, which provides a basis for the MR-TADF unit to transfer energy positively to the iridium complex unit. Fig.17 The photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material IrBT5BN in toluene solution finally synthesized in this example shows that IrBT5BN only shows the emission peak of the iridium complex unit (662nm), and the emission peak of the MR-TADF unit (around 500nm) is not observed, indicating that the MR-TADF unit and the iridium complex unit have extremely high forward energy transfer efficiency.

[0178] Embodiment 9

[0179] MR-TADF-phosphorescent self-sensitized system luminescent material PtIQCzFl4BN, chemical formula is C 95 H 95 BN4O2Pt, molecular structure formula is:

[0180]

[0181] The specific operation process is as follows:

[0182] Step 1: Synthesis of organic ligand containing MR-TADF sensitizing unit

[0183] This example shares the same organic ligand containing the MR-TADF sensitizing unit as Example 6. Since its detailed synthesis steps have been listed in Step 1 of Example 6, Step 1 in the specific operation process of this example is omitted here. However, this does not mean that the operation process for synthesizing the organic ligand containing the MR-TADF sensitizing unit required in this example does not include the above-mentioned Step 1.

[0184] Step 2:

[0185]

[0186] Weigh 0.20g L-IQCzFl4BN (0.16mmol), 67.1mg potassium chloroplatinate (0.16mmol) in a SCHLENK reaction tube, add 60mL of a mixed solvent of THF and water (v / v, 3 / 1) under N2 atmosphere, and stir at 90℃ for 16h. After the reaction system is cooled to room temperature, extract with dichloromethane three times, combine the organic phases and dry with anhydrous sodium sulfate, remove the solvent by vacuum rotary evaporation, and redissolve the residue in 20mL dry dichloromethane solution. At the same time, dissolve 24.7mg Na(acac) (0.20mmol) in 4mL methanol and drop into the above dichloromethane reaction solution, and stir at room temperature for 2h. After the reaction is completed, the reaction solution is used to remove the solvent by a rotary evaporator, and the residual solid is separated and purified by thin layer chromatography, and the developing solvent is petroleum ether / dichloromethane = 3 / 1. Finally, 120.5mg of dark red solid is obtained with a yield of 48.7%.

[0187] 1H NMR (400MHz, CDCl3, δ): 9.37 (s, 1H), 9.19 (d, J = 2.0Hz, 2H), 9.09 (d, J = 9.6Hz, 1H), 8.54 (s, 2H), 8.51 (d,J=1.6Hz,2H),8.35(d,J=8.8Hz,2H),8.32–8.29(m,1H),8.28(d,J=2.0Hz,2H),8.26(d,J=7.2Hz, 2H),8.18(s,2H),8.09(d,J=8.0Hz,1H),7.86–7.80(m,2H),7.68(d,J=1.6Hz,1H),7.60–7.50(m,3H) ,7.53–7.48(m,4H),5.53(s,1H),2.16(s,3H),1.93(s,3H),1.70(s,18H),1.69(s,6H),1.50(s,36H).

[0188] Fig. 9 The ultraviolet absorption spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material PtIQCzFl4BN in toluene solution finally synthesized in this embodiment shows that the energy of the characteristic absorption band of the MR-TADF unit at 470nm is higher than the MLCT absorption band of the platinum complex unit at 500-550nm, which provides a basis for the MR-TADF unit to transfer energy positively to the platinum complex unit. Fig.18 This is the photoluminescence spectrum of the MR-TADF-phosphorescent self-sensitized system luminescent material PtIQCzFl4BN in toluene solution that was finally synthesized in this example. PtIQCzFl4BN only shows the emission peaks of the platinum complex unit (536nm and 672nm), and the emission peak of the MR-TADF unit (around 480nm) is not obviously observed, indicating that the MR-TADF unit and the platinum complex unit have extremely high forward energy transfer efficiency.

[0189] In summary, the present invention aims at the shortcomings of the current TADF-sensitized phosphorescence strategy in suppressing the serious efficiency roll-off under high brightness of phosphorescent OLEDs. The multi-resonance thermally activated delayed fluorescence (MR-TADF) molecules are covalently bonded to the phosphorescent luminescent molecules by interrupting the conjugation at a large torsion angle (close to 90°) to construct a MR-TADF-phosphorescent self-sensitized system luminescent material. By shortening the distance between the two, the The resonant energy transfer rate and the large torsion angle between the two fully suppress Dexter energy transfer to improve the upconversion efficiency of the MR-TADF sensitization unit T1→S1, significantly reduce the triplet exciton density of the light-emitting layer, and effectively solve the serious efficiency roll-off problem of phosphorescent OLEDs under high brightness.

Claims

1. A MR-TADF-phosphorescence self-sensitization system luminescent material based on energy transfer optimization, characterized in that: The MR-TADF molecule has a covalent bond with the phosphorescent molecule of the iridium or platinum complex by interrupting the conjugation at a large torsion angle close to 90 degrees.

2. The MR-TADF-phosphorescence self-sensitization system luminescent material based on energy transfer optimization according to claim 1, characterized in that: Its general chemical formula is: Wherein, Ar1 is selected from any of the following structures: Ar2 is selected from any of the following structures; R1 is any substituent selected from hydrogen atom, fluorine atom, methyl, methoxy, isopropyl or tert-butyl: BN is selected from any of the following structures, and the substitution position and number of the BN structure on Ar1 or Ar2 can be varied; R2 is any substituent selected from tert-butyl, carbazole, acridine, phenothiazine, phenoxazine or diphenylamine; R3 is any substituent selected from hydrogen, methyl, methoxy or isopropyl: O^X is an acetylacetone or pyridine carboxylic acid auxiliary ligand, X is an oxygen and nitrogen atom, and is selected from any of the following structures:

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