Multi-resonance thermal activation delayed fluorescence compound with space heavy atom effect and organic electroluminescent device

Abstract

The invention relates to a multi-resonance thermal activation delayed fluorescence compound with a space heavy atom effect and an organic electroluminescent device, and belongs to the field of organic luminescent materials. In the compound, a heavy atom-containing structural unit and a multi-resonance thermal activation delayed fluorescence unit are connected through a space confinement molecular skeleton; molecular orbits of the two are subjected to spatial interaction to promote the anti-intersystem crossing process of the multi-resonance thermal activation delayed fluorescence unit, so that the delayed fluorescence lifetime is shortened, and the device performance is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of luminescent materials, and in particular relates to an organic electroluminescent material, specifically a multi-resonance thermally activated delayed fluorescence compound with spatial heavy atom effect. Background Art

[0002] Organic light-emitting diodes (OLEDs) have the advantages of bright colors, fast response speed, large viewing angle, low driving voltage, energy saving, light weight and flexible display. The fluorescent materials of traditional OLEDs are expensive, highly toxic, and have low exciton utilization. The emergence of thermally activated delayed fluorescence (TADF) materials has promoted the development of OLED technology.

[0003] Multiresonance Thermally Activated Delayed Fluorescence (MR-TADF) materials are based on an intramolecular push-pull electron system formed by electron-rich and electron-deficient courtyards embedded in a fused aromatic ring skeleton. They have the characteristics of thermally activated delayed fluorescence effect and narrow spectrum emission, with an exciton utilization rate of up to 100% and high luminescent color purity. They have broad application prospects in the preparation of high-efficiency, wide-color gamut organic light-emitting devices. However, unlike traditional TADF materials with donor-acceptor structures, MR-TADF uses the resonance effect of electron-rich and electron-deficient atoms in the fused molecular skeleton to regulate the distribution of frontier molecular orbitals. Here, the frontier molecular orbital refers to the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), that is, the HOMO-LUMO energy level orbital. HOMO and LUMO are alternately distributed on adjacent atoms, so it is difficult to achieve effective HOMO and LNMO separation. Therefore, MR-TADF usually exhibits a large singlet energy level difference (ΔE ST ), low Reverse Intersystem Crossing (RISC) rate (k RISC ≈10 4 -10 5 s -1 ) and a longer fluorescence lifetime, which in turn leads to a serious device efficiency roll-off.

[0004] By embedding heavy atoms in the MR-TADF molecular skeleton or introducing structural units containing heavy atoms on the periphery of its units, the heavy atom effect is used to enhance the spin-orbit coupling (SOC) between singlet and triplet states, which is an effective means to promote the RISC process. However, structural units containing heavy atoms can produce strong electronic coupling and charge transfer states with the MR-TADF luminescent core; on the other hand, heavy atoms with large atomic radius embedded in the MR-TADF molecular skeleton will destroy its own planar molecular configuration, resulting in molecular configuration distortion and causing large excited state structural relaxation (Structural Relaxation). Therefore, the above schemes will inevitably lead to the problems of red shift and broadening of the luminescence spectrum, thereby affecting the purity of the luminescence color.

[0005] How to promote the RISC process of MR-TADF materials and further improve their luminescence performance without affecting their luminescence properties is a problem that needs to be solved urgently. Summary of the invention

[0006] In order to address the deficiencies in the prior art, the present invention proposes a multiple resonance thermally activated delayed fluorescence compound and an organic electroluminescent device with a spatial heavy atom effect. In the compound, a heavy atom structural unit (Heavy Atom Unit, HAU) and a MR-TADF unit are connected by a spatially restricted molecular skeleton, avoiding a strong electrical coupling effect caused by a direct bond between the two. The molecular orbitals between the two can also produce a spatial interaction, which can effectively reduce the delayed fluorescence lifetime and improve the device performance.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0008] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the molecular formula of which is shown in formula (I):

[0009]

[0010] in:

[0011] is a structural unit containing a heavy atom, wherein the atomic number of the heavy atom is greater than 13,

[0012] is a multiple resonance thermally activated delayed fluorescence unit,

[0013] SCB is a spatially restricted molecular skeleton that can confine structural units containing heavy atoms and multi-resonance thermally activated delayed fluorescence units to within the spatial range;

[0014] m is the number of structural units containing heavy atoms in the above compound, m is an integer from 1 to 10, n is the number of multiple resonance thermally activated delayed fluorescence units in the above compound, n is an integer from 1 to 10, and p is the number of spatially restricted molecular skeletons in the above compound, p is an integer from 1 to 10.

[0015] In the present invention, the unit containing a heavy atom is selected from any one of the following formulas HAU-1 to HAU-9:

[0016]

[0017] Among them, the dotted line indicates bonding or non-bonding;

[0018] K is selected from B, N, R 3 -P=one of O;

[0019] Q 1 , Q 2 and Q 3 Each independently selected from R 4 -Si-R 5 , R 6 -Ge-R 7 , S, Se, Te;

[0020] R in formula HAU-1 to HAU-8 1 ~R 7 Each is independently selected from H, halogen, -CN, -NO 2 , substituted or unsubstituted C1-C22 straight-chain alkyl, substituted or unsubstituted C1-C22 branched alkyl, substituted or unsubstituted C1-C22 cycloalkyl, substituted or unsubstituted C1-C22 alkoxy chain, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C3-C20 heteroaryl, a group formed by a combination of the above groups, or a group formed by a fusion of the above groups; or R 1 ~R 7 They can be connected by chemical bonds to form a bridge structure.

[0021] Preferably, the above-mentioned unit containing a heavy atom is selected from any one of the groups formed by lacking a hydrogen atom in the following formulas HAU-1-1 to HAU-9-12:

[0022]

[0023]

[0024]

[0025] In the present invention, the multiple resonance thermally activated delayed fluorescence unit is selected from any one of the following formulas MR-1 to MR-4:

[0026]

[0027] Wherein, G1 to G2 are each independently selected from non-bonded, single-bonded, BR 1 , R 1 -CR 2 , R 1 -Si-R 2 NR 1 , PR 1 , R 1 -P=O, C=O, S=O, O=S=O, O, S, Se or Te;

[0028] M1~M4 are selected from BR 1 NR 1 , PR 1 , R 1 -P=O, C=O, S=O, O=S=O, O, S, Se or Te;

[0029] K1-K2 are each independently selected from B, N, P, P=O;

[0030] BR in G1~G2 and M1~M4 1 , R 1 -CR 2 , R 1 -Si-R 2 NR 1 , PR 1 With R 1 -P=R in O 1 and R 2 are each independently selected from substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl; or said BR 1 , R 1 -CR 2 , R 1 -Si-R 2 NR 1 , PR 1 With R 1 -P=R in O 1 and R 2 Through a linker or single bond to the adjacent A 1 ~A 5 One or two bonds in the 1 , R 1 -CR 2 , R 1 -Si-R2 NR 1 , PR 1 With R 1 -P=R in O 1 and R 2 A is connected to one or two adjacent M1 to M4 via a linker or a single bond; 1 ~A 5 Each is independently selected from a C6-C60 aromatic ring or a C3-C60 aromatic heterocyclic ring.

[0031] Among them, A in the above-mentioned multiple resonance thermally activated delayed fluorescence unit 1 ~A 5 Each is independently selected from any one of the following formulas 1 to 53:

[0032]

[0033]

[0034] Wherein, L1, L2 and L3 are each independently selected from: (i) H, halogen, -CN, -NO 2 , OH; (ii) a straight chain, branched or cycloalkyl or alkoxy chain containing 1 to 30 carbon atoms, wherein one or more non-adjacent carbon atoms may be substituted by O, S, Si, -CO-O-, and one or more hydrogen atoms may be substituted by halogen; (iii) a substituted or unsubstituted C6-C60 aryl or C5-C60 heteroaryl; L1, L2 and L3 may be connected by chemical bonds to form a bridge structure.

[0035] Preferably, the above-mentioned multiple resonance thermally activated delayed fluorescence unit is selected from any one of the following formulas MR-1-1 to MR-4-6:

[0036]

[0037]

[0038]

[0039]

[0040]

[0041] Among them, R in formula MR-1-1 to MR-4-6 1 ~R 12 Each is independently selected from H, halogen, -CN, -NO 2, substituted or unsubstituted C1-C22 straight-chain alkyl, substituted or unsubstituted C1-C22 branched alkyl, substituted or unsubstituted C1-C22 cycloalkyl, substituted or unsubstituted C1-C22 alkoxy chain, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C3-C20 heteroaryl, a group formed by a combination of the above groups, or a group formed by a fusion of the above groups; or R 1 ~R 12 They are connected by chemical bonds to form a bridge structure.

[0042] Furthermore, the above-mentioned multiple resonance thermally activated delayed fluorescence unit is selected from any one of the following formulas MR-1-1-1 to MR-4-5-1:

[0043]

[0044]

[0045]

[0046] In the present invention, the space-restricted molecular skeleton is selected from any one of the following formulas SCB-1 to SCB-6:

[0047]

[0048] Among them, T 1 and T 2 Each independently selected from a single bond, R 4 -CR 5 , R 4 -Si-R 5 , R 4 -Ge-R 5 , O, S, Se, Te;

[0049] R in SCB-1 to SCB-6 1 ~R 5 Each is independently selected from H, halogen, -CN, -NO 2 , substituted or unsubstituted C1-C22 straight-chain alkyl, substituted or unsubstituted C1-C22 branched alkyl, substituted or unsubstituted C1-C22 cycloalkyl, substituted or unsubstituted C1-C22 alkoxy chain, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C3-C20 heteroaryl, a group formed by a combination of the above groups, or a group formed by a fusion of the above groups; or R 1 ~R 5 They are connected by chemical bonds to form a bridge structure.

[0050] Furthermore, the space-restricted molecular skeleton is selected from any one of the following formulas SCB-1-1 to SCB-6-1:

[0051]

[0052]

[0053] Furthermore, the multi-resonance thermally activated delayed fluorescence compound with spatial heavy atom effect is one of the following formulas A-1-C-33:

[0054]

[0055]

[0056]

[0057]

[0058] In the present invention, an organic electroluminescent device comprises the above-mentioned multi-resonance thermally activated delayed fluorescence compound with spatial heavy atom effect, and uses it as the luminescent material of the organic electroluminescent device.

[0059] Furthermore, the organic electroluminescent device includes a substrate, an anode arranged on the substrate, an organic layer arranged on the anode, and a cathode arranged on the organic layer, wherein there is at least one organic layer, and at least one organic electroluminescent layer in the organic layer, and the organic electroluminescent layer includes one or more of the above-mentioned multiple resonance thermally activated delayed fluorescence compounds with spatial heavy atom effect.

[0060] Furthermore, the substrate is made of glass or plastic with a thickness of 0.3 to 0.7 mm; the anode is a material based on hole injection, a conductive metal or a conductive metal oxide, preferably indium tin oxide; the cathode is a metal, one of calcium, magnesium, barium, aluminum, and silver, preferably aluminum.

[0061] Furthermore, the organic layer between the anode and the organic electroluminescent layer includes a hole injection layer, a hole transport layer and an electron blocking layer, and the organic layer between the organic electroluminescent layer and the cathode includes a hole blocking layer and an electron injection / transport layer.

[0062] In the present invention, the method for preparing the above-mentioned organic electroluminescent device comprises the following steps:

[0063] forming an anode on the substrate;

[0064] forming one or more organic layers on the anode, including an organic electroluminescent layer;

[0065] A cathode is formed on the organic layer.

[0066] Among them, the organic electroluminescent layer and the organic layers below it can be formed on the anode by solution spin coating, inkjet printing, offset printing or stereo printing. After the organic electroluminescent layer is formed, a hole blocking layer and an electron injection / transport layer can be formed on its surface by vacuum evaporation or spin coating; the formation method of the cathode includes but is not limited to vacuum deposition.

[0067] Compared with the prior art, the present application adopts a multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect as a luminescent material for an organic electroluminescent device. In the compound, the structural unit HAU containing heavy atoms and the MR-TADF unit are connected by a spatially restricted molecular skeleton, thereby avoiding a strong electrical coupling effect caused by the bond between the two. On the other hand, the spatially restricted molecular skeleton can confine the two to a certain spatial range, and the molecular orbitals of the two can produce spatial interactions, enhancing the spin-orbit coupling of the MR-TADF unit, thereby promoting the RISC process of MR-TADF, thereby reducing the delayed fluorescence lifetime, suppressing the device efficiency roll-off, and providing a new approach for the development of high-performance MR-TADF materials and their organic light-emitting devices. DETAILED DESCRIPTION

[0068] The present invention is further described below in conjunction with specific preferred embodiments of the specification, but the protection scope of the present invention is not limited thereby.

[0069] Example 1

[0070] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0071]

[0072] In a nitrogen atmosphere, 5 mmol of compound 1, 4.5 mmol of compound 2, and 0.25 mmol of Pd (pph) were added to a 100 ml Schlenk bottle. 3 ) 4 、15mmol K 2 CO 3 , 30 mL tetrahydrofuran (THF) and 8 mL deionized water, heated to 65°C, reacted for 8 h. The organic phase was washed with clean water and dried in vacuo. The obtained solid was separated and purified by silica gel column chromatography (petroleum ether / dichloromethane = 2:1) to obtain compound 3 as a yellow solid with a yield of 78%. Elemental analysis structure (C 59 H 55 BN 2O): theoretical value C: 86.54; H: 6.77; B: 1.32; N: 3.42; measured value C: 87.02; H: 6.58; B: 1.39; N: 3.28; MALDI-TOF mass spectrum: theoretical value 818.1; experimental value 818.4 (M + ).

[0073] Under nitrogen atmosphere, 3mmol of compound 4 and 20mL of anhydrous THF were added to a 100ml Schlenk bottle, stirred to dissolve, and cooled to -78°C. Subsequently, 3.3mmol of n-butyllithium solution was added dropwise to the reaction system. After reacting for 2h, a THF solution of compound 3 (2.7mmol, 20mL) was added dropwise to the reaction system. After stirring for 1h, the mixture was heated to room temperature and reacted for 8h. After the reaction solution was washed with water, dried, and concentrated, the resulting solid was dissolved in 20mL of acetic acid AcOH, and then 1mL of hydrochloric acid HCl was added, the temperature was raised to 100°C, and the reaction was reacted for 5h. The reaction solution was poured into 100mL of water, filtered to obtain a solid, and separated and purified by silica gel column chromatography (petroleum ether / dichloromethane = 4:1) to obtain compound A-2 as a yellow solid with a yield of 68%. Elemental analysis structure (C 77 H 66 BN 3 Se): theoretical value C: 82.34; H: 5.92; B: 0.96; N: 3.74; test value C: 82.68; H: 5.27; B: 1.04; N: 3.59; MALDI-TOF mass spectrum: theoretical value 1123.5; experimental value 1123.5 (M + ).

[0074] Example 2

[0075] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0076]

[0077] The synthetic route and preparation conditions of compound A-3 are consistent with those of compound A-2, and the initial raw material is replaced by compound 4 from compound 1. The target compound is a yellow solid with a yield of 65%. Elemental analysis structure (C 123 H 113 B 2 N 5 Se): theoretical value C: 83.85; H: 6.46; B: 1.23; N: 3.98; test value C: 84.51; H: 6.21; B: 1.32; N: 3.79; MALDI-TOF mass spectrum: theoretical value 1761.8; experimental value 1762.8 (M + ).

[0078] Example 3

[0079] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0080]

[0081] The synthetic route and preparation conditions of compound A-6 are consistent with those of compound A-2, and the initial raw material is replaced by compound 6 from compound 1. The target compound is a yellow solid with a yield of 59%. Elemental analysis structure (C 77 H 66 BN 3 OSe): theoretical value C: 81.19; H: 5.84; B: 0.95; N: 3.69; measured value C: 81.87; H: 5.61; B: 1.03; N: 3.57; MALDI-TOF mass spectrum: theoretical value 1139.5; experimental value 1139.5 (M + ).

[0082] Example 4

[0083] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0084]

[0085] Under nitrogen atmosphere, 10 mmol of compound 8, 22 mmol of compound 9, and 0.5 mmol of Pd (pph) were added to a 250 ml Schlenk bottle. 3 ) 4 , 66mmol K 2 CO 3 , 65 mL THF and 35 mL deionized water, heated to 65 ° C, reacted for 8 hours. The organic phase was washed with water and dried in vacuo, and the obtained solid was separated and purified by silica gel column chromatography (petroleum ether / dichloromethane = 4:1) to obtain compound 10 as a white solid with a yield of 74%. Elemental analysis structure (C 56 H 47 N 3 Se 2 ): Theoretical value C: 73.11; H: 5.15; N: 4.57; Test value C: 73.69; H: 4.98; N: 4.83; MALDI-TOF mass spectrum: theoretical value 921.2; experimental value 921.2 (M + ).

[0086] Under nitrogen atmosphere, 5.0 mmol of compound 10, 6.0 mmol of compound 11, and 0.25 mmol of Pd were added to a 100 ml Schlenk bottle.2 (dba) 3 , 1.0mmol t-Bu 3 PHB 4 , 15mmol t-BuONa and 75mL toluene, heated to 105°C, reacted for 8h. The organic phase was washed with water and dried in vacuo, and the obtained solid was separated and purified by silica gel column chromatography (petroleum ether / dichloromethane = 4:1) to obtain compound A-19, a yellow solid, with a yield of 69%. Elemental analysis structure (C 102 H 94 BN 5 Se 2 ): Theoretical value C: 78.60; H: 6.08; B: 0.69; N: 4.49; Test value C: 79.35; H: 5.97; B: 0.73; N: 4.54; MALDI-TOF mass spectrum: theoretical value 1559.6; experimental value 1558.6 (M + ).

[0087] Example 5

[0088] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0089]

[0090] In a 100 ml Schlenk bottle under nitrogen atmosphere, 10 mmol of compound 12, 12 mmol of compound 2, and 0.25 mmol of Pd (pph) were added. 3 ) 4 , 33mmol K 2 CO 3 , 40mL THF and 16mL deionized water, heated to 65°C, reacted for 8h. The organic phase was washed with water and dried in vacuo, and the obtained solid was separated and purified by silica gel column chromatography (petroleum ether / dichloromethane = 4:1) to obtain compound 13 as a yellow solid with a yield of 62%. Elemental analysis structure (C 66 H 72 BN 3 ): Theoretical value C: 86.34; H: 7.90; B: 1.18; N: 4.58; Test value C: 86.83; H: 7.67; B: 1.21; N: 4.45; MALDI-TOF mass spectrum: theoretical value 917.6; experimental value 917.6 (M + ).

[0091] Under nitrogen atmosphere, 5.0 mmol of compound 13, 6.0 mmol of compound 14, and 0.25 mmol of Pd were added to a 100 ml Schlenk bottle. 2 (dba)3 , 1.0mmol t-Bu 3 PHB 4 , 15mmol t-BuONa and 75mL toluene, heated to 105°C, reacted for 8h. The organic phase was washed with water and dried in vacuo, and the obtained solid was separated and purified by silica gel column chromatography (petroleum ether / dichloromethane = 4:1) to obtain compound A-20, a yellow solid, with a yield of 54%. Elemental analysis structure (C 85 H 87 BN 4 Se): theoretical value C: 81.39; H: 6.99; B: 0.86; N: 4.47; test value C: 81.87; H: 6.86; B: 0.92; N: 4.53; MALDI-TOF mass spectrum: theoretical value 1254.6; experimental value 1254.6 (M + ).

[0092] Example 6

[0093] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0094]

[0095] The synthetic route and preparation conditions of compound A-21 are consistent with those of compound A-20, and the initial raw material is replaced by compound 8 from compound 12. The target compound is a yellow solid with a yield of 59%. Elemental analysis structure (C 131 H 134 B 2 N 6 Se): theoretical value C: 83.11; H: 7.13; B: 1.14; N: 4.44; test value C: 83.68; H: 6.89; B: 1.22; N: 4.38; MALDI-TOF mass spectrum: theoretical value 1893.0; experimental value 1894.0 (M + ).

[0096] Example 7

[0097] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0098]

[0099] The synthetic route and preparation conditions of compound 17 are consistent with those of compound A-20, and the initial raw material is replaced by compound 16 instead of compound 13. Compound 17 is a white solid with a yield of 52%. Elemental analysis structure (C 36 H 23 N 3Se): theoretical value C: 74.99; H: 4.02; N: 7.29; test value C: 75.32; H: 3.94; N: 7.41; MALDI-TOF mass spectrum: theoretical value 577.1; experimental value 577.1 (M + ).

[0100] The synthetic route and preparation conditions of compound A-32 are consistent with those of compound A-19, and the initial raw material is replaced by compound 17 instead of compound 10. Compound A-32 is a yellow solid with a yield of 61%. Elemental analysis structure (C 82 H 70 BN 5 Se): theoretical value C: 81.04; H: 5.81; B: 0.89; N: 5.76; test value C: 80.67; H: 5.86; B: 0.92; N: 5.81; MALDI-TOF mass spectrum: theoretical value 1215.5; experimental value 1215.5 (M + ).

[0101] Example 8

[0102] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0103]

[0104] The synthetic route and preparation conditions of compound A-33 are consistent with those of compound A-32, and the initial raw material is replaced by compound 18 from compound 14. The target compound is a yellow solid with a yield of 47%. Elemental analysis structure (C 146 H 127 B 2 N 9 Se): theoretical value C: 83.18; H: 6.07; B: 1.03; N: 5.98; test value C: 83.52; H: 5.96; B: 1.21; N: 5.79; MALDI-TOF mass spectrum: theoretical value 2108.0; experimental value 2108.0 (M + ).

[0105] Example 9

[0106] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0107]

[0108] Compound A-47 was prepared by two-step Suzuki reaction. The specific reaction conditions and preparation process were the same as those of compound 10. Compound A-47 was obtained as a yellow solid with a yield of 47%. Elemental analysis structure (C74 H 70 BN 3 Se): theoretical value C: 81.45; H: 6.47; B: 0.99; N: 3.85; test value C: 81.83; H: 6.38; B: 1.04; N: 3.79; MALDI-TOF mass spectrum: theoretical value 1091.5; experimental value 1091.5 (M + ).

[0109] Example 10

[0110] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0111]

[0112] The synthetic route and preparation conditions of compound A-49 are consistent with those of compound A-47, and the initial raw material is replaced by compound 22 instead of compound 20. The target compound is a yellow solid with a yield of 42%. Elemental analysis structure (C 84 H 72 BN 3 Se): theoretical value C: 83.16; H: 5.98; B: 0.89; N: 3.46; test value C: 83.57; H: 5.86; B: 0.95; N: 3.35; MALDI-TOF mass spectrum: theoretical value 1213.5; experimental value 1213.5 (M + ).

[0113] Embodiment 11

[0114] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0115]

[0116] The synthetic route and preparation conditions of compound A-36 are consistent with those of compound A-47, and the initial raw material is replaced by compound 23 from compound 20. The target compound is a yellow solid with a yield of 39%. Elemental analysis structure (C 79 H 72 BN 3 OSe): theoretical value C: 81.15; H: 6.21; B: 0.92; N: 3.59; measured value C: 81.48; H: 6.09; B: 1.03; N: 3.47; MALDI-TOF mass spectrum: theoretical value 1169.5; experimental value 1270.5 (M + ).

[0117] Example 12

[0118] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0119]

[0120] The synthetic route and preparation conditions of compound B-20 are consistent with those of compound A-36, and the initial raw material is replaced by compound 25 instead of compound 9. The target compound is a yellow solid with a yield of 44%. Elemental analysis structure (C 74 H 67 BN 2 O 2 Se): theoretical value C: 80.35; H: 6.11; B: 0.98; N: 2.53; test value C: 80.62; H: 5.97; B: 1.04; N: 2.48; MALDI-TOF mass spectrum: theoretical value 1106.5; experimental value 1106.5 (M + ).

[0121] Embodiment 13

[0122] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0123]

[0124] The synthetic route and preparation conditions of compound C-14 are consistent with those of compound A-36, except that compound 2 in the second step reaction is replaced by compound 27. The target compound is a yellow solid with a yield of 51%. Elemental analysis structure (C 59 H 50 BNOS 2 Se): theoretical value C: 75.15; H: 5.34; B: 1.15; N: 1.49; test value C: 75.47; H: 5.26; B: 1.21; N: 1.44; MALDI-TOF mass spectrum: theoretical value 943.2; experimental value 943.2 (M + ).

[0125] Embodiment 14

[0126] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0127]

[0128] The synthetic route and preparation conditions of compound C-18 are consistent with those of compound A-36, except that compound 2 in the second step reaction is replaced by compound 28. The target compound is a yellow solid with a yield of 47%. Elemental analysis structure (C 57H 37 BN 2 O 2 Se): theoretical value C: 78.54; H: 4.28; B: 1.24; N: 3.21; test value C: 78.83; H: 4.31; B: 1.18; N: 3.07; MALDI-TOF mass spectrum: theoretical value 872.2; experimental value 872.2 (M + ).

[0129] Embodiment 15

[0130] A multi-resonance thermally activated delayed fluorescence compound with a spatial heavy atom effect, the structural formula and the monomers used are as follows:

[0131]

[0132] The synthetic route and preparation conditions of compound C-32 are consistent with those of compound A-36, except that compound 2 in the second step reaction is replaced by compound 29. The target compound is a yellow solid with a yield of 47%. Elemental analysis structure (C 53 H 34 N 2 O 3 Se): theoretical value C: 77.08; H: 4.15; N: 3.39; test value C: 77.31; H: 4.08; N: 3.53; MALDI-TOF mass spectrum: theoretical value 826.2; experimental value 826.2 (M + ).

[0133] The photophysical properties of Examples 1-15 provided by the present invention were characterized, and the results are shown in Table 1.

[0134] Table 1 Photophysical properties of the multi-resonance thermally activated delayed fluorescence compounds with spatial heavy atom effect prepared in Examples 1-15 of the present invention

[0135]

[0136] Note: The delayed fluorescence lifetime in the table is obtained by doping the compound at a concentration of 1wt% in polystyrene to make the tested sample, and testing it using a time-resolved fluorescence spectrometer; the half-peak width is the peak width at half the peak height of the fluorescence spectrum at room temperature, where the fluorescence spectrum is obtained by doping the compound at a concentration of 1*10 -5 The concentration of mol / L was dissolved in toluene solution to prepare the tested sample.

[0137] As can be seen from the data in Table 1, the multiple resonance thermally activated delayed fluorescence compounds with spatial heavy atom effect in Examples 1-15 provided by the present invention all exhibit the characteristics of narrow spectral emission, and their half-peak width is 21-27nm. At the same time, the above compounds all exhibit short delayed fluorescence lifetimes, and their delayed fluorescence lifetimes are less than 20μs, which overcomes the problem of long lifetimes of traditional multiple resonance thermally activated delayed fluorescence compounds.

[0138] Device Embodiment

[0139] The specific device structure used is ITO / TAPC (40nm) / TCTA (10nm) / EML (30nm) / TSPO1 (5nm) / TmPyPB (25nm) / LiF (1nm) / Al, where ITO, PEDOT:PSS, TSPO1, TmPyPB, LiF, and Al are anode, hole injection layer, hole blocking layer, electron transport layer, electron injection layer, and cathode, respectively.

[0140]

[0141] The EML is made of the invented luminescent compound and the host material (mCBP) in a mass ratio of 1:9. The device manufacturing process is as follows: 4×10 -4 Pa, TAPC, TCTA, EML, TSPO1, TmPyPB, LiF and Al were deposited in sequence on oxygen ITO supported on a glass substrate to obtain an organic electroluminescent device.

[0142] Comparative Example 1

[0143]

[0144] In Comparative Example 1, the device structure and preparation process are the same as those of the device embodiment, and the luminescent material in the luminescent layer is replaced with a comparative compound Ctrl-1 that does not have a spatial heavy atom effect. The performance parameters of the obtained electronic light-emitting device are listed in Table 2.

[0145] Table 2 Performance parameters of organic electroluminescent devices obtained from device examples and comparative examples

[0146]

[0147] Note: Half-peak width is the peak width at half the peak height of the electroluminescence spectrum at room temperature; Turn-on voltage is the value at which the brightness is 1 cd m -2 The maximum external quantum efficiency is obtained according to the current-voltage curve and electroluminescence spectrum of the device according to the calculation method described in the literature (Jpn. J. Appl. Phys. 2001, 40, L783).

[0148] It can be seen from the above data that based on the same MR-TADF luminescent unit, the electroluminescent spectrum and spectral half-peak width of the multi-resonance thermally activated delayed fluorescence compound with spatial heavy atom effect provided by the present invention are basically consistent, indicating that in the above compound, the introduction of heavy atoms can still enable the MR-TADF unit to maintain the original luminescent peak position and narrow spectrum emission characteristics. In addition, the compound provided by the present invention has high brightness (1000cd / m 2 ) allows the device efficiency to maintain a relatively high level, with an external quantum efficiency of 16-20%, which is significantly better than the control example, indicating that the technical solution provided by the present invention can effectively suppress the roll-off of the device efficiency, overcome the problem of low efficiency of traditional MR-TADF materials at high brightness, and provide a new approach to the development of high-performance MR-TADF OLEDs.

[0149] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A multi-resonance thermally activated delayed fluorescence compound with spatial heavy atom effect, characterized in that: Its molecular formula is shown in formula (I): in: is a structural unit containing a heavy atom, wherein the atomic number of the heavy atom is greater than 13, is a multiple resonance thermally activated delayed fluorescence unit, SCB is a spatially restricted molecular skeleton that can confine structural units containing heavy atoms and multi-resonance thermally activated delayed fluorescence units to within the spatial range; m is the number of structural units containing heavy atoms in the above compound, m is an integer from 1 to 10, n is the number of multiple resonance thermally activated delayed fluorescence units in the above compound, n is an integer from 1 to 10, and p is the number of spatially restricted molecular skeletons in the above compound, p is an integer from 1 to 10.

2. The compound according to claim 1, characterized in that: The unit containing heavy atoms is selected from any one of the following formulas HAU-1 to HAU-9: Among them, the dotted line indicates bonding or non-bonding; K is selected from one of B, N, and R3-P=O; Q1, Q2 and Q3 are each independently selected from one of R4-Si-R5, R6-Ge-R7, S, Se, Te; R1 to R7 in formulas HAU-1 to HAU-8 are each independently selected from H, halogen, -CN, -NO2, substituted or unsubstituted C1 to C22 straight chain alkyl, substituted or unsubstituted C1 to C22 branched alkyl, substituted or unsubstituted C1 to C22 cycloalkyl, substituted or unsubstituted C1 to C22 alkoxy chain, substituted or unsubstituted C6 to C20 aryl, substituted or unsubstituted C3 to C20 heteroaryl, a group formed by a combination of the above groups, or a group formed by a condensation of the above groups; or R1 to R7 can be connected by chemical bonds to form a bridge structure.

3. The compound according to claim 2, characterized in that: The unit containing a heavy atom is selected from any one of the groups formed by lacking a hydrogen atom in the following formulas HAU-1-1 to HAU-9-12:

4. The compound according to claim 1, characterized in that: The multiple resonance thermally activated delayed fluorescence unit is selected from any one of the following formulas MR-1 to MR-4: Wherein, G1 to G2 are each independently selected from non-bonded, single-bonded, BR 1 , R 1 -CR 2 , R 1 -Si-R 2 NR 1 , PR 1 , R 1 -P=O, C=O, S=O, O=S=O, O, S, Se or Te; M1~M4 are selected from BR 1 NR 1 , PR 1 , R 1 -P=O, C=O, S=O, O=S=O, O, S, Se or Te; K1-K2 are each independently selected from B, N, P, P=O; BR in G1~G2 and M1~M4 1 , R 1 -CR 2 , R 1 -Si-R 2 NR 1 , PR 1 With R 1 -P=R in O 1 and R 2 are each independently selected from substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl; or said BR 1 , R 1 -CR 2 , R 1 -Si-R 2 NR 1 , PR 1 With R 1 -P=R in O 1 and R 2 It is connected to one or two of the adjacent A1 to A5 via a linker or a single bond; or the BR 1 , R 1 -CR 2 , R 1 -Si-R 2 NR 1 , PR 1 With R 1 -P=R in O 1 and R 2 It is bonded to one or two adjacent M1-M4 via a linking group or a single bond; A1-A5 are each independently selected from a C6-C60 aromatic ring or a C3-C60 aromatic heterocyclic ring.

5. The compound according to claim 4, characterized in that: A1 to A5 in the multiple resonance thermally activated delayed fluorescence unit are each independently selected from any one of the following formulas 1 to 53: Wherein, L1, L2 and L3 are each independently selected from: (i) H, halogen, -CN, -NO2, OH; (ii) a straight chain, branched chain or cycloalkyl or alkoxy chain containing 1 to 30 carbon atoms, wherein one or more non-adjacent carbon atoms may be substituted by O, S, Si, -CO-O-, and one or more hydrogen atoms may be substituted by halogen; (iii) a substituted or unsubstituted C6~C60 aryl group or C5~C60 heteroaryl group; L1, L2 and L3 may be connected by chemical bonds to form a bridge structure.

6. The compound according to claim 4, characterized in that: The multiple resonance thermally activated delayed fluorescence unit is selected from any one of the following formulas MR-1-1 to MR-4-6: Among them, R1 to R in formula MR-1-1 to MR-4-6 12 Each is independently selected from H, halogen, -CN, -NO2, substituted or unsubstituted C1-C22 straight-chain alkyl, substituted or unsubstituted C1-C22 branched alkyl, substituted or unsubstituted C1-C22 cycloalkyl, substituted or unsubstituted C1-C22 alkoxy chain, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C3-C20 heteroaryl, a group formed by a combination of the above groups, or a group formed by a fusion of the above groups; or R1-R 12 They are connected by chemical bonds to form a bridge structure.

7. The polymer compound according to claim 6, characterized in that: The multiple resonance thermally activated delayed fluorescence unit is selected from any one of the following formulas MR-1-1-1 to MR-4-5-1:

8. The compound according to claim 1, characterized in that: The space-restricted molecular skeleton is selected from any one of the following formulas SCB-1 to SCB-6: Wherein, T1 and T2 are each independently selected from a single bond, R4-C-R5, R4-Si-R5, R4-Ge-R5, O, S, Se, Te; R1 to R5 in SCB-1 to SCB-6 are each independently selected from H, halogen, -CN, -NO2, substituted or unsubstituted C1 to C22 straight-chain alkyl, substituted or unsubstituted C1 to C22 branched alkyl, substituted or unsubstituted C1 to C22 cycloalkyl, substituted or unsubstituted C1 to C22 alkoxy chain, substituted or unsubstituted C6 to C20 aryl, substituted or unsubstituted C3 to C20 heteroaryl, a group formed by a combination of the above groups, or a group formed by a fusion of the above groups; or R1 to R5 are connected by chemical bonds to form a bridge structure.

9. The compound according to claim 8, characterized in that: The spatially restricted molecular skeleton is selected from any one of the following formulas SCB-1-1 to SCB-6-1:

10. An organic electroluminescent device, comprising the multi-resonance thermally activated delayed fluorescence compound with spatial heavy atom effect as claimed in any one of claims 1 to 9, characterized in that: The polymer compound is used as the luminescent material of the organic electroluminescent device.

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