Cyano-modified double-boron narrow-band luminescent material, preparation method thereof and electroluminescent device

Abstract

The invention relates to the technical field of fluorescent materials, in particular to a cyano-modified double-boron narrow-band light-emitting material, a preparation method thereof and an electroluminescent device.The cyano-modified double-boron narrow-band light-emitting material is a multi-resonance thermally-activated delayed fluorescent compound which has a multi-resonance molecular skeleton and can be used as a light-emitting device. The energy level difference between the single excited state and the triple excited state is small, the exciton utilization rate is 100% theoretically, and meanwhile the narrow-band light-emitting property is shown. Moreover, the luminescent material is modified by cyano groups, on one hand, molecular structure relaxation is further limited, so that the luminescent material shows an ultra-narrow emission spectrum; on the other hand, the charge transfer effect in molecules is enhanced, the coupling effect between single triplet states is enhanced, and the reverse intersystem crossing rate can be increased. In addition, the luminescent material is used for preparing an organic electroluminescent device, so that the preparation of a high-performance device with ultrahigh color purity is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent materials, and in particular to a cyano-modified double-boron narrow-band luminescent material and a preparation method thereof, and an electroluminescent device. Background Art

[0002] In the field of optoelectronics, organic light-emitting devices (OLEDs) have attracted widespread attention due to their excellent brightness, contrast, and color saturation.

[0003] Thermally activated delayed fluorescent materials are recognized as the third generation of luminescent materials in the field of OLEDs because of their extremely small single-triplet energy level difference and theoretical 100% exciton utilization rate even without heavy metal atoms. Among them, thermally activated delayed fluorescent materials are mainly divided into traditional donor-acceptor type and multi-resonance type. Compared with traditional donor-acceptor type thermally activated delayed fluorescent materials, multi-resonance thermally activated delayed fluorescent materials have a more rigid structural skeleton and localized electronic properties, and thus exhibit narrow-band emission properties. They show higher color purity at the same maximum emission wavelength, and have particularly great application prospects in the field of high-definition displays.

[0004] Nevertheless, the half-width of the multi-resonance thermally activated delayed fluorescence materials reported so far is above 100meV, which is difficult to meet the BT.2020 color coordinate standard. Therefore, it is imperative to develop materials with a half-width below 100meV. Reducing the structural relaxation of molecules is one of the effective ways to reduce the half-width of the emission spectrum, but the modification methods for the multi-resonance skeleton are very limited, and the conventional ring-locking method is difficult to synthesize.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a cyano-modified diboron narrow-band luminescent material and a preparation method and an electroluminescent device, aiming to solve the problem of large half-peak width of existing multiple resonance thermally activated delayed fluorescence materials.

[0007] The technical solution of the present invention is as follows:

[0008] A cyano-modified biboron narrow-band luminescent material, the molecular structure of which is shown in formula (1):

[0009]

[0010] In formula (1), R 1 , R 2 are independently selected from hydrogen, cyano, C 1 -C 12 Alkyl, C 4 -C 60One of aryl, diphenylamino, and 9-carbazolyl; Ar 1 is selected from 2,6-dialkylphenyl, 2,4,6-trialkylphenyl, 2,6-diphenylphenyl; Y is selected from bondless, elementless, single bond, oxygen, sulfur, selenium, substituted methylene;

[0011] A 2 Select one of the following structures:

[0012] A method for preparing a cyano-modified diboron narrow-band luminescent material comprises the following steps:

[0013] Will and Cs 2 CO 3 Mixing, heating and stirring for the first time, obtaining

[0014] The and Pd 2 (dba) 3 , S-Phos and t BuONa, and then heated and stirred for the second time to obtain

[0015] After dissolving in ultra-dry o-dichlorobenzene, boron tribromide was added and after the first heating reaction, the obtained

[0016] The With Pd 2 (dba) 3 、Xphos、K 2 CO 3 、Zn(CN) 2 The mixture is mixed with Zn powder and solvent, and subjected to a second heating reaction to obtain a cyano-modified diboron narrow-band luminescent material.

[0017] An electroluminescent device comprises a luminescent layer; the luminescent layer contains the cyano-modified double-boron narrow-band luminescent material.

[0018] Beneficial effects: The present invention provides a cyano-modified diboron narrow-band luminescent material and a preparation method and an electroluminescent device. The provided cyano-modified diboron narrow-band luminescent material is a multi-resonance thermally activated delayed fluorescence compound. This type of compound has a multi-resonance molecular skeleton, a small energy level difference between single and triplet excited states, a theoretical 100% exciton utilization rate, and exhibits narrow-band luminescence properties. Moreover, the luminescent material is modified by cyano to further restrict the relaxation of the molecular structure, so that it exhibits an ultra-narrow emission spectrum; on the other hand, the charge transfer effect within the molecule is enhanced, and the coupling effect between single and triplet states is enhanced, which is beneficial to improve the reverse intersystem crossing rate. In addition, the use of this type of luminescent material in the preparation of organic electroluminescent devices is beneficial to the preparation of high-performance devices with ultra-high color purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the preparation process of a cyano-modified diboron narrow-band luminescent material;

[0020] Figure 2 The figure is a schematic structural diagram of an electroluminescent device of the present invention. DETAILED DESCRIPTION

[0021] The present invention provides a cyano-modified biboron narrow-band luminescent material and a preparation method thereof, and an electroluminescent device. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0023] The present invention provides a cyano-modified diboron narrow-band luminescent material, the molecular structure of which is shown in formula (1):

[0024]

[0025] In formula (1), R 1 , R 2 are independently selected from hydrogen, cyano, C 1 -C 12 Alkyl, C 4 -C 60 One of aryl, diphenylamino, and 9-carbazolyl; Ar1 is selected from 2,6-dialkylphenyl, 2,4,6-trialkylphenyl, 2,6-diphenylphenyl; Y is selected from bondless, elementless, single bond, oxygen, sulfur, selenium, substituted methylene;

[0026] A 2 Select one of the following structures:

[0027] In this embodiment, the provided cyano-modified diboron narrow-band luminescent material is a multi-resonance thermally activated delayed fluorescence compound, which has a multi-resonance molecular skeleton, a small energy level difference between single and triplet excited states, a theoretical 100% exciton utilization rate, and exhibits narrow-band luminescence properties. Moreover, the luminescent material is modified by cyano, on the one hand, further restricting the relaxation of the molecular structure, causing it to exhibit an ultra-narrow emission spectrum; on the other hand, the charge transfer effect within the molecule is enhanced, and the coupling effect between single and triplet states is enhanced, which is beneficial to improve the reverse intersystem crossing rate. In addition, using this type of luminescent material to prepare organic electroluminescent devices is beneficial to the preparation of high-performance devices with ultra-high color purity.

[0028] Specifically, the cyano-modified diboron narrow-band luminescent material is obtained by introducing cyano groups into a boron nitrogen fused ring skeleton with a multiple resonance effect. The introduction of cyano groups can effectively limit molecular relaxation, further reduce the half-peak width of the multiple resonance thermally activated delayed fluorescence material, and help to obtain an organic luminescent material with ultra-high color purity; and the luminescent material has a multiple resonance molecular skeleton. Through cyano modification, on the one hand, the relaxation of the molecular structure is further suppressed, showing an ultra-narrow emission spectrum; on the other hand, the enhanced intramolecular charge transfer effect is conducive to improving the reverse intersystem crossing rate.

[0029] In some embodiments, the cyano-modified diboron narrow-band luminescent material is selected from one of the following structures:

[0030]

[0031]

[0032]

[0033]

[0034] The above-mentioned cyano-modified diboron narrow-band luminescent materials all have narrow-band luminescence characteristics, and have narrower emission spectra than most multi-resonance thermally activated delayed fluorescence materials. Using them as guest materials for the luminescent layer can make the device not only have ultra-high external quantum efficiency, but more importantly, the extremely narrow emission spectrum is conducive to obtaining ultra-high color purity.

[0035] In addition, Figure 1 As shown, the present invention also provides a method for preparing a cyano-modified diboron narrow-band luminescent material, comprising the steps of:

[0036] Step S10: and Cs 2 CO 3 Mixing, heating and stirring for the first time, obtaining

[0037] Step S20: and Pd 2 (dba) 3 , S-Phos and t BuONa, and then heated and stirred for the second time to obtain

[0038]

[0039] Step S30: dissolving in ultra-dry o-dichlorobenzene and adding boron tribromide, and heating for the first time to obtain

[0040] Step S40: With Pd 2 (dba) 3 、Xphos、K 2 CO 3 、Zn(CN) 2 The mixture is mixed with Zn powder and solvent, and subjected to a second heating reaction to obtain a cyano-modified diboron narrow-band luminescent material.

[0041] In this embodiment, first synthesize Then, the chlorine-directed one-pot borylation method was used to obtain The chlorine atom is then replaced with a cyano group by palladium catalysis to obtain a cyano-modified diboron narrow-band luminescent material. The preparation process of this method is simple and easy to implement, and the reaction conditions are relatively mild, which is suitable for large-scale production.

[0042] Moreover, the cyano-modified diboron narrow-band luminescent material prepared by this method is obtained by introducing cyano groups into the boron nitrogen fused ring skeleton with multiple resonance effects. The introduction of cyano groups can effectively limit molecular relaxation, further reduce the half-peak width of the multiple resonance thermally activated delayed fluorescence material, and help to obtain organic luminescent materials with ultra-high color purity.

[0043] In some embodiments, the temperature of the first heating and stirring treatment is 100°C-155°C, and the time of the first heating and stirring treatment is 12h-24h; the temperature of the second heating and stirring treatment is 120°C-140°C, and the time of the second heating and stirring treatment is 12h-24h. The reaction conditions are relatively mild, and under these conditions, a high purity can be synthesized

[0044] Specifically, Figure 1 As shown, the steps S10 to S20 specifically include: in an inert atmosphere, compound m1, compound m2 and Cs 2 CO 3 The DMF mixture was stirred at 100-155°C for 12-24 hours, cooled to room temperature, added with water for precipitation, filtered with ethanol, and washed repeatedly for 3-4 times to obtain compound c (the same method can be used to prepare the substituent R 3 , R 4 ); Compound c, compound m3, Pd 2 (dba) 3 , S-Phos and t BuONa was added to the reaction flask, and then xylene was injected. The reaction system was heated and stirred at 120-140° C. for 12-24 hours. After cooling to room temperature, the reaction mixture was extracted with dichloromethane and water. The organic phase was collected and vacuum dried, and then purified by silica gel column chromatography to obtain compound a.

[0045] In a preferred embodiment, the temperature of the first heating and stirring treatment is 155°C, and the time of the first heating and stirring treatment is 24 hours; the temperature of the second heating and stirring treatment is 140°C, and the time of the second heating and stirring treatment is 24 hours.

[0046] In some embodiments, the temperature of the first heating reaction is 150°C-220°C, and the time of the first heating reaction is 24h-36h; the temperature of the second heating reaction is 120°C-140°C, and the time of the second heating reaction is 12h-36h. Under the above conditions, the reaction can be completed and the purity is high. and cyano-modified diboron narrow-band luminescent materials.

[0047] Specifically, Figure 1As shown, the steps S40 to S50 specifically include: under the protection of inert gas, adding compound a into a pressure-resistant tube and dissolving it in ultra-dry o-dichlorobenzene, adding an excess of boron tribromide, heating to 150-220° C. to react for about one day, cooling to room temperature after the reaction is completed, slowly adding methanol to quench in an ice-water bath, precipitating a large amount of solid, then filtering under reduced pressure, and collecting the filter residue to obtain compound b; under the protection of inert gas, mixing compound b and Pd 2 (dba) 3 、Xphos、K 2 CO 3 、Zn(CN) 2 The mixture is mixed with Zn powder in anhydrous DMF, heated to 120-140°C for reaction for 12-36 hours, and after the reaction is completed, cooled to room temperature, extracted with dichloromethane and water, and the filtrate is spin-dried and purified by column chromatography to obtain a cyano-modified diboron narrow-band luminescent material.

[0048] In a preferred embodiment, the temperature of the first heating reaction is 220° C., and the time of the first heating reaction is 36 hours; the temperature of the second heating reaction is 140° C., and the time of the second heating reaction is 36 hours.

[0049] In some embodiments, the and Pd 2 (dba) 3 , S-Phos and t The molar ratio of BuONa is (2-3):1:(0.05-0.2):(0.1-0.5):(2-5). When the mass ratio of the reactants is controlled within the above range, the reaction can be fully carried out to obtain a high purity It can also avoid the waste of raw materials and reduce environmental pollution.

[0050] In some embodiments, the With Pd 2 (dba) 3 、Xphos、K 2 CO 3 、Zn(CN) 2 The molar ratio of Zn powder is (1-2):(0.1-0.2):(0.2-0.5):(2-5):(1.3):(1-3). After mixing according to the above mass ratio and heating for the second time, a cyano-modified diboron narrow-band luminescent material with high purity and complete reaction can be obtained.

[0051] In a preferred embodiment, the With Pd 2 (dba) 3 、Xphos、K2 CO 3 、Zn(CN) 2 The mass ratio of Ag and Zn powder is 1:0.1:0.4:4:2:2.

[0052] In addition, the present invention also provides an electroluminescent device, comprising a light-emitting layer; the light-emitting layer contains the cyano-modified double-boron narrow-band light-emitting material.

[0053] In this embodiment, the light-emitting material is modified with cyano groups, which further limits the relaxation of the molecular structure, so that it exhibits an ultra-narrow emission spectrum; on the other hand, the charge transfer effect within the molecule is enhanced, and the coupling effect between single and triplet states is enhanced, which is beneficial to increase the reverse intersystem crossing rate. This type of light-emitting material is used to prepare organic electroluminescent devices, which is beneficial to prepare high-performance devices with ultra-high color purity.

[0054] In some embodiments, the mass fraction of the cyano-modified diboron narrow-band luminescent material in the luminescent layer is 0.5%-5%. By controlling the mass fraction of the cyano-modified diboron narrow-band luminescent material in the luminescent layer within the above range, a high-performance device with ultra-high color purity can be obtained.

[0055] In some embodiments, the light-emitting layer is composed of a host material and a guest material, or is formed by co-doping a host material, a sensitizing material and a guest material; the guest material includes the cyano-modified double boron narrow-band light-emitting material

[0056] In some embodiments, the electroluminescent device further comprises an anode layer, a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer stacked in sequence; the light-emitting layer is disposed between the electron blocking layer and the hole blocking layer.

[0057] In some embodiments, the thickness of the hole injection layer (HI) is 4nm-6nm, the thickness of the hole transport layer (HT) is 40nm-50nm, the thickness of the electron blocking layer (EBL) is 8nm-12nm, the thickness of the hole blocking layer (HBL) is 15nm-25nm, the thickness of the electron transport layer (ET) is 25nm-35nm, the thickness of the electron injection layer (EI) is 1nm-4nm, the thickness of the cathode layer is 80nm-120nm; the thickness of the light-emitting layer is 20nm-30nm.

[0058] In some embodiments, the material of the anode layer is ITO, the material of the cathode layer is Al, and the material of the hole injection layer is (HAT-CN), the material of the hole transport layer is (TAPC) and (TCTA), the material of the electron blocking layer is (mCBP), the material of the hole blocking layer is (POT2T), the material of the electron transport layer is (ANT-BIZ), the material of the electron injection layer is (Liq), but not limited thereto.

[0059] In some embodiments, the method for preparing the electroluminescent device comprises the steps of:

[0060] Step S100: using a glass substrate with a certain thickness of ITO as a transparent support substrate by evaporating;

[0061] Step S200: sequentially evaporating a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and an aluminum film on the transparent support substrate to obtain an electroluminescent device.

[0062] Specifically, the electroluminescent device is prepared by vacuum evaporation, and a glass substrate with a certain thickness of ITO is evaporated as a transparent supporting substrate; the transparent supporting substrate is fixed on a substrate holder of an evaporation device, and a molybdenum evaporation boat containing each layer of electroplating material and the luminescent material is installed; a tungsten evaporation boat containing 8-hydroxyquinoline-lithium and aluminum is placed respectively; a hole injection layer, a hole transport layer, an electron blocking layer, a luminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer and an aluminum film are sequentially evaporated on the ITO film of the transparent supporting substrate.

[0063] In some embodiments, the ratio of the host material, the sensitizing material and the luminescent material in the luminescent layer can be adjusted by the evaporation speed to achieve a desired doping ratio.

[0064] The following examples are further given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention.

[0065] Example 1

[0066] This example prepares compound (1) The specific preparation steps are as follows:

[0067] Under an inert gas atmosphere, the compound (m1, 3.28 g, 19.63 mmol), (m2, 3.91 g, 18.69 mmol) and Cs 2 CO3 (9.14 g, 28.04 mmol) of DMF was stirred at 155°C for 24 hours. After cooling to room temperature, water was added to precipitate, filtered with ethanol, and washed repeatedly 3 to 4 times to obtain 5.0g.

[0068] Under an inert gas atmosphere, (4.14 g, 11.61 mmol), (m3, 1.53 g, 4.84 mmol), Pd 2 (dba) 3 (0.13 g, 0.14 mmol), S-Phos (0.20 g, 0.48 mmol) and t BuONa (1.86 g, 19.36 mmol) was added to the reaction flask. Then, xylene was injected. The reaction system was heated and stirred at 140°C for 24 hours. After cooling to room temperature, the reaction mixture was extracted with dichloromethane and water, and the organic phase was collected and vacuum dried, and then purified by silica gel column chromatography to obtain (Compound a).

[0069] Under inert gas protection, reactant a (2.0 g, 2.30 mmol) was added to a pressure tube and dissolved in ultra-dry o-dichlorobenzene, and an excess of boron tribromide was added, and the mixture was heated to 220°C for one day. After the reaction was completed, the mixture was cooled to room temperature, and methanol was slowly added to quench the mixture in an ice-water bath to precipitate a large amount of solids, which were then filtered under reduced pressure and the residue was collected to obtain the product. (Intermediate b).

[0070] Under inert gas protection, intermediate b (0.85 g, 0.96 mmol), Pd 2 (dba) 3 (0.17g, 0.19mmol), Xphos (0.17g, 0.29mmol), K 2 CO 3 (0.03 g, 0.19 mmol), Zn(CN) 2 (0.17 g, 1.44 mmol) and Zn powder (0.63 g, 9.6 mmol) were mixed in anhydrous DMF and heated to 140°C for 36 hours. After the reaction was completed, it was cooled to room temperature, extracted with dichloromethane and water, and the filtrate was dried and separated and purified by column chromatography to obtain the cyano-modified diboron target compound (1) The product was a light yellow solid powder with a yield of 59%. MS (MALDI-TOF): m / z 868.38 [M + ].

[0071] Its H NMR spectrum data is 1H NMR (500 MHz, CDCl 3 )δ(ppm):10.53(s,1H),9.12(d,J=7.5Hz,2H),8.47(m,4H),8.31(d,J=7.6Hz,2H),7.74(s,2H),7.69(t,J=7.4Hz,4H),7.59(s,2H),7.53(d,J=7.5Hz,4H),7.33(d,J=7.5Hz,2H),7.17(d,J=7.8Hz,4H),6.67(d,J=1.1Hz,2H),5.76(s,1H),1.82(s,12H)., indicating that compound (1) was successfully prepared in this example.

[0072] Example 2

[0073] This example prepares compound (2) The preparation method of compound (2) is substantially the same as that of Example 1, except that: m1 is selected

[0074] The compound (2) was prepared by the above route. The product was a light yellow solid powder with a yield of 50%. MS (MALDI-TOF): m / z 924.43 [M + ].

[0075] Example 3

[0076] This example prepares compound (3) The preparation method of compound (3) is substantially the same as that of Example 1, except that: m1 is selected

[0077] The compound (3) was prepared by the above route. The product was a light yellow solid powder with a yield of 45%. MS (MALDI-TOF): m / z 1092.60 [M + ].

[0078] Example 4

[0079] This example prepares compound (4) The preparation method of compound (4) is substantially the same as that of Example 1, except that: m1 is selected

[0080] The compound (4) was prepared by the above route. The product was an orange solid powder with a yield of 39%. MS (MALDI-TOF): m / z 864.33 [M + ]. 1 H NMR (500 MHz, CDCl 3)δ (ppm): 10.80 (s, 1H), 9.28 (d, J = 7.5Hz, 2H), 8.50 (d, J = 7.3Hz, 2H), 8.42 (d, J = 8.3Hz, 2H), 8.37 (s, 2H), 8.31 (d, J = 7.6Hz, 2H), 7.91 (t, J = 7. 5Hz,2H),7.69(t,J=7.8Hz,2H),7.53(t,J=7.4Hz,2H),7.31(s,2H),7.17(d,J=7.8Hz,4H),6.67(d,J=1.1Hz,2H),5.80(s,1H),1.80(s,12H).

[0081] Example 5

[0082] This example prepares compound (5) The preparation method of compound (5) is substantially the same as that of Example 1, except that: m1 is selected

[0083] The compound (5) was prepared by the above route. The product was an orange solid powder with a yield of 44%. MS (MALDI-TOF): m / z 920.41 [M + ].

[0084] Example 6

[0085] This example prepares compound (6) The preparation method of compound (6) is substantially the same as that of Example 1, except that: m1 is selected

[0086] The compound (6) was prepared by the above route. The product was an orange solid powder with a yield of 88%. MS (MALDI-TOF): m / z 1088.53 [M + ].

[0087] Example 7

[0088] This example prepares compound (7) The preparation method of compound (7) is substantially the same as that of Example 1, except that: m1 is selected

[0089] The compound (7) was prepared by the above route. The product was an orange solid powder with a yield of 35%. MS (MALDI-TOF): m / z 1168.38 [M + ].

[0090] Example 8

[0091] This example prepares compound (8) The preparation method of compound (8) is substantially the same as that of Example 1, except that: m1 is selected

[0092] The compound (8) was prepared by the above route. The product was an orange solid powder with a yield of 31%. MS (MALDI-TOF): m / z 1524.44 [M + ].

[0093] Example 9

[0094] This example prepares compound (9) The preparation method of compound (9) is substantially the same as that of Example 1, except that: m1 is selected

[0095] The compound 9 was prepared by the above route, and the product was an orange-red solid powder with a yield of 46%. MS (MALDI-TOF): m / z 1533.39 [M + ].

[0096] Example 10

[0097] This example prepares compound (10) The preparation method of compound (10) is substantially the same as that of Example 1, except that: m1 is selected

[0098] The compound 10 was prepared by the above route. The product was an orange solid powder with a yield of 27%. MS (MALDI-TOF): m / z 964.37 [M + ].

[0099] Embodiment 11

[0100] This example prepares compound (11) The preparation method of compound (11) is substantially the same as that of Example 1, except that: m1 is selected

[0101] The compound 11 was prepared by the above route, and the product was an orange solid powder with a yield of 31%. MS (MALDI-TOF): m / z 1144.48 [M + ].

[0102] Example 12

[0103] This example prepares compound (12) The preparation method of compound (12) is substantially the same as that of Example 1, except that: m1 is selected

[0104] The compound (12) was prepared by the above route. The product was an orange solid powder with a yield of 24%. MS (MALDI-TOF): m / z 1076.26 [M + ].

[0105] Example 13

[0106] This example prepares compound (13) The preparation method of compound (13) is substantially the same as that of Example 1, except that: m1 is selected

[0107] The compound 13 was prepared by the above route. The product was an orange solid powder with a yield of 24%. MS (MALDI-TOF): m / z 1171.15 [M + ].

[0108] Embodiment 14

[0109] This example prepares compound (14) The preparation method of compound (14) is substantially the same as that of Example 1, except that: m1 is selected

[0110] The compound 14 was prepared by the above route. The product was an orange solid powder with a yield of 40%. MS (MALDI-TOF): m / z 1096.56 [M + ].

[0111] Embodiment 15

[0112] This example prepares compound (15) The preparation method of compound (15) is substantially the same as that of Example 1, except that: m1 is selected

[0113] The compound (15) was prepared by the above route. The product was an orange solid powder with a yield of 38%. MS (MALDI-TOF): m / z 1035.58 [M + ].

[0114] Example 16

[0115] This example prepares compound (16) The preparation method of compound (16) is substantially the same as that of Example 1, except that: m1 is selected

[0116] The compound (16) was prepared by the above route. The product was an orange solid powder with a yield of 19%. MS (MALDI-TOF): m / z 1341.50 [M +].

[0117] Embodiment 17

[0118] This example prepares compound (17) The preparation method of compound (17) is substantially the same as that of Example 1, except that: m1 is selected

[0119] The compound (17) was prepared by the above route. The product was an orange solid powder with a yield of 37%. MS (MALDI-TOF): m / z 948.43 [M + ].

[0120] Embodiment 18

[0121] This example prepares compound (18) The preparation method of compound (18) is substantially the same as that of Example 1, except that: m1 is selected

[0122] The compound (18) was prepared by the above route. The product was an orange solid powder with a yield of 35%. MS (MALDI-TOF): m / z 1196.17 [M + ].

[0123] Embodiment 19

[0124] This example prepares compound (19) The preparation method of compound (19) is substantially the same as that of Example 1, except that: m1 is selected

[0125] The compound (19) was prepared by the above route. The product was an orange solid powder with a yield of 31%. MS (MALDI-TOF): m / z 1194.45 [M + ].

[0126] Embodiment 20

[0127] This example prepares compound (20) The preparation method of compound (20) is substantially the same as that of Example 1, except that: m1 is selected

[0128] The compound (20) was prepared by the above route. The product was an orange-yellow solid powder with a yield of 41%. MS (MALDI-TOF): m / z 896.33 [M + ].

[0129] Embodiment 21

[0130] This example prepares compound (45) The preparation method of compound (45) is substantially the same as that of Example 1, except that: m1 is selected m3 selection

[0131]

[0132] The compound (45) was prepared by the above route. The product was a yellow solid powder with a yield of 48%. MS (MALDI-TOF): m / z 1168.64 [M + ].

[0133] Embodiment 22

[0134] This example prepares compound (57) The preparation method of compound (57) is substantially the same as that of Example 1, except that: m1 is selected m3 selection

[0135]

[0136] The compound (57) was prepared by the above route. The product was a yellow solid powder with a yield of 50%. MS (MALDI-TOF): m / z 1196.47 [M + ].

[0137] Embodiment 23

[0138] This example prepares compound (59) The preparation method of compound (59) is substantially the same as that of Example 1, except that: m1 is selected m3 selection

[0139] The compound (59) was prepared by the above route. The product was a yellow solid powder with a yield of 45%. MS (MALDI-TOF): m / z 1143.54 [M + ].

[0140] Embodiment 24

[0141] This example prepares compound (60) The preparation method of compound (60) is substantially the same as that of Example 1, except that: m1 is selected m3 selection

[0142]

[0143] The compound (60) was prepared by the above route with a yield of 35%, MS (MALDI-TOF): m / z 1144.42 [M+ ].

[0144] Embodiment 25

[0145] This embodiment provides an organic electroluminescent device, such as Figure 2 As shown, it includes an anode layer 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9 and a cathode layer 10 stacked in sequence from bottom to top on a substrate 1; the device structure is ITO / HI (5nm) / HT (45nm) / EBL (10nm) / EML (25nm) / HBL (20nm) / ET (30nm) / EI (2nm) / Al (100nm).

[0146] The device was prepared by vacuum evaporation, and the evaporation environment was 2×10 -5 Pa, the evaporation rate of the hole injection layer 3, the hole transport layer 4, the electron blocking layer 5, the light emitting layer 6, the hole blocking layer 7, the electron transport layer 8 and the electron injection layer 9 is The evaporation rate of the cathode layer 10 is

[0147] The anode layer 2 is made of ITO material, i.e. indium tin oxide material;

[0148] The material of the hole injection layer is (HAT-CN), the material of the hole transport layer is (TAPC) and (TCTA), the material of the electron blocking layer is (mCBP), the material of the hole blocking layer is (POT2T), the material of the electron transport layer is (ANT-BIZ), the material of the electron injection layer is (Liq).

[0149] The light-emitting layer is formed by co-doping the host material and the guest material, wherein the host material is a compound (DMIC-TRZ), the guest material is selected from the compound (4) in the cyano-modified double boron narrow-band luminescent material, and the doping amount of the guest material accounts for 1wt% of the total mass of the host material and the guest material.

[0150] Embodiment 26

[0151] In Example 25, the doping ratio of the guest material was changed to 3% and the other conditions remained unchanged to prepare the corresponding electroluminescent device.

[0152] Embodiment 27

[0153] In Example 25, the doping ratio of the guest material was changed to 5%, and the other conditions remained unchanged to prepare the corresponding electroluminescent device.

[0154] Embodiment 28

[0155] In Example 25, the guest material is replaced with compound (5) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0156] Embodiment 29

[0157] In Example 26, the guest material is replaced with compound (5) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0158] Embodiment 30

[0159] In Example 27, the guest material is replaced with compound (5) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0160] Embodiment 31

[0161] In Example 25, the guest material is replaced with compound (7) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0162] Embodiment 32

[0163] In Example 26, the guest material is replaced with compound (7) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0164] Embodiment 33

[0165] In Example 27, the guest material is replaced with compound (7) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0166] Embodiment 34

[0167] In Example 25, the guest material is replaced with compound (8) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0168] Embodiment 35

[0169] In Example 25, the guest material is replaced with compound (10) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0170] Embodiment 36

[0171] In Example 25, the guest material is replaced with compound (11) in the cyano-modified diboron narrow-band luminescent material of the present invention, and other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0172] Embodiment 37

[0173] In Example 25, the guest material is replaced with compound (17) in the cyano-modified diboron narrow-band luminescent material of the present invention, and the other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0174] Embodiment 38

[0175] In Example 25, the guest material is replaced with compound (20) in the cyano-modified diboron narrow-band luminescent material of the present invention, and the other conditions remain unchanged to prepare the corresponding electroluminescent device.

[0176] The electroluminescent properties of the electroluminescent devices prepared in Examples 25 to 38 were tested, and the performance test results are shown in Table 1:

[0177] Table 1

[0178]

[0179]

[0180] The results in Table 1 show that the cyano-modified diboron narrow-band luminescent materials described in the present invention all have narrow-band luminescence characteristics, and have a narrower emission spectrum relative to most multi-resonance thermally activated delayed fluorescent materials. The device in the present invention not only has an ultra-high external quantum efficiency, but more importantly, the extremely narrow emission spectrum is conducive to obtaining ultra-high color purity. Under appropriate doping ratios, the maximum external quantum efficiency of the device can be as high as or even higher than 40%, and the color coordinate y value of the green light device can be as high as 0.79, meeting the BT.2020 green light standard, and having very high color purity. Therefore, the present invention can not only maintain the high performance of the multi-resonance thermally activated delayed fluorescent material, but also further narrow the spectrum and improve the color purity of the device, solving the problem that the color purity of the current multi-resonance thermally activated delayed fluorescent green light material does not meet the BT.2020 standard, and is expected to promote the practical application of multi-resonance thermally activated delayed fluorescent materials in the field of ultra-high-definition display.

[0181] In summary, the present invention provides a cyano-modified diboron narrow-band luminescent material and a preparation method and an electroluminescent device. The cyano-modified diboron narrow-band luminescent material provided is a multi-resonance thermally activated delayed fluorescence compound. This type of compound has a multi-resonance molecular skeleton, a small energy level difference between single and triplet excited states, a theoretical 100% exciton utilization rate, and exhibits narrow-band luminescent properties. Moreover, the luminescent material is modified by cyano, on the one hand, to further limit the relaxation of the molecular structure, so that it exhibits an ultra-narrow emission spectrum; on the other hand, the charge transfer effect within the molecule is enhanced, and the coupling effect between single and triplet states is enhanced, which is beneficial to improve the reverse intersystem crossing rate. In addition, the use of this type of luminescent material in the preparation of organic electroluminescent devices is beneficial to the preparation of high-performance devices with ultra-high color purity.

[0182] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A cyano-modified diboron narrow-band luminescent material, characterized in that: The general molecular structure is shown in formula (1): In formula (1), R1 and R2 are independently selected from hydrogen, cyano, C1-C 12 Alkyl, C4-C 60 One of aryl, diphenylamino, and 9-carbazolyl; Ar1 ​​is selected from one of 2,6-dialkylphenyl, 2,4,6-trialkylphenyl, and 2,6-diphenylphenyl; Y is selected from one of bondless and elementless, single bond, oxygen, sulfur, selenium, and substituted methylene; A2 is selected from one of the following structures:

2. The cyano-modified diboron narrow-band luminescent material according to claim 1, characterized in that: The cyano-modified diboron narrow-band luminescent material is selected from one of the following structures:

3. A method for preparing a cyano-modified diboron narrow-band luminescent material as claimed in any one of claims 1 to 2, characterized in that: Includes steps: Will and Cs2CO3, and then heated and stirred for the first time to obtain The and , Pd2(dba)3, S-Phos and t BuONa, and then heated and stirred for the second time to obtain After dissolving in ultra-dry o-dichlorobenzene, boron tribromide was added and after the first heating reaction, the obtained The The mixture is mixed with Pd2(dba)3, Xphos, K2CO3, Zn(CN)2, Zn powder and solvent, and subjected to a second heating reaction to obtain a cyano-modified diboron narrow-band luminescent material.

4. The method for preparing the cyano-modified diboron narrow-band luminescent material according to claim 3, characterized in that: The temperature of the first heating and stirring treatment is 100°C-155°C, and the time of the first heating and stirring treatment is 12h-24h; the temperature of the second heating and stirring treatment is 120°C-140°C, and the time of the second heating and stirring treatment is 12h-24h.

5. The method for preparing the cyano-modified diboron narrow-band luminescent material according to claim 3, characterized in that: The temperature of the first heating reaction is 150°C-220°C, and the time of the first heating reaction is 24h-36h; the temperature of the second heating reaction is 120°C-140°C, and the time of the second heating reaction is 12h-36h.

6. The method for preparing the cyano-modified diboron narrow-band luminescent material according to claim 3, characterized in that: Said and , Pd2(dba)3, S-Phos and t The molar ratio of BuONa is (2-3):1:(0.05-0.2):(0.1-0.5):(2-5).

7. The method for preparing the cyano-modified diboron narrow-band luminescent material according to claim 3, characterized in that: Said The molar ratios with Pd2(dba)3, Xphos, K2CO3, Zn(CN)2 and Zn powder are (1-2):(0.1-0.2):(0.2-0.5):(2-5):(1.3):(1-3).

8. An electroluminescent device, characterized in that: It comprises a light-emitting layer; the light-emitting layer contains the cyano-modified diboron narrow-band light-emitting material as described in any one of claims 1 to 2.

9. The electroluminescent device according to claim 8, characterized in that The mass fraction of the cyano-modified diboron narrow-band luminescent material in the luminescent layer is 0.5%-5%.

10. The electroluminescent device according to claim 8, characterized in that The electroluminescent device also includes an anode layer, a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer which are stacked in sequence; the light-emitting layer is arranged between the electron blocking layer and the hole blocking layer.

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