A-pi-D type TADF red light / near infrared luminescent material and application thereof in OLEDs

Abstract

The invention belongs to the technical field of organic photoelectric materials, and particularly discloses an A-pi-D type TADF red light / near-infrared light-emitting material and application thereof in OLEDs (organic light-emitting diodes). The luminescent material is constructed by taking acenaphthylene [1, 2-b] pyrazine-8, 9-dinitrile, acenaphthylene [1, 2-b] quinoxaline-9, 10-dinitrile and acenaphthylene [1, 2-b] pyrazine-9, 10-dinitrile as acceptor units, tert-butyl oxygen bridged triphenylamine as a donor unit and benzene or anthracene as a pi bridge, and realizes efficient red light and near-infrared light emission, so that the luminescent material has the advantages that the luminescent material is simple in structure and low in cost; the thermal decomposition temperature is 450 DEG C or above, and good thermal stability is achieved. The emission peaks of the prepared solution processing type organic light-emitting device are respectively located at 678 nm and 780 nm, the corresponding maximum external quantum efficiencies are respectively 6.13% and 2.15%, and the organic light-emitting device has an attractive application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic photoelectric materials, and specifically discloses a kind of A-π-D type TADF red / near-infrared light-emitting materials and its application in OLEDs. BACKGROUND

[0002] Organic light-emitting diodes (OLEDs) have been widely used in smart wear, smart display, flexible display, healthy lighting and other fields due to their self-luminescence, low energy consumption, flexibility, wide color gamut and other advantages. Since Professor Deng Qingyun published the first organic light-emitting diode in 1987, great progress has been made in the theory and light-emitting materials of organic light-emitting diodes.

[0003] The development of organic light-emitting materials has also gone through three important stages: the first generation of traditional fluorescent materials represented by Alq3, which only utilizes 25% of singlet excitons for light emission, has a low theoretical maximum external quantum efficiency; the second generation of phosphorescent materials represented by Ir, Pt and other complexes can utilize triplet excitons for direct light emission under the spin-orbit coupling induced by heavy atoms, and the light-emitting efficiency is significantly improved; due to the presence of noble metals in phosphorescent materials, the development and application of phosphorescent materials are limited in terms of cost, efficiency and other factors. The third generation of thermally activated delayed fluorescence (TADF) materials represented by 4CzIPN utilizes a small singlet-triplet energy gap (Δ E st ), which can make triplet excitons return to singlet state through reverse intersystem crossing (RISC) process, achieving 100% exciton utilization rate of delayed fluorescence. In recent years, great breakthroughs have been made in efficiency based on blue and green TADF materials.

[0004] However, the development of red to near-infrared TADF materials is relatively slow compared to blue and green TADF materials. The main reasons are: (1) due to the influence of the energy gap law, the fluorescence quantum yield rapidly decreases with the red shift of the emission spectrum, while the non-radiative transition rate caused by internal conversion increases; (2) long-wavelength light-emitting materials generally have a large conjugated system, which will exacerbate the fluorescence quenching caused by π-π stacking; (3) long-wavelength emission generally requires the construction of strong donor-acceptor interaction, which is easy to cause the increase of molecular polarity, thereby increasing the intermolecular interaction and quenching. SUMMARY

[0005] In order to overcome the deficiencies in the prior art, the present application designs a kind of A-π-D type TADF red / near-infrared light-emitting material, introduces π bridge, breaks the energy level distribution between donor and acceptor, reduces Δ E stThe application improves intercavity crossing rate, restrains non-radiation process, simultaneously regulates spatial structure distribution of donor and acceptor, adjusts dihedral angle between donor and acceptor, and obtains an organic electroluminescence diode with excellent performance.

[0006] The application provides a kind of linear A-π-D type TADF red / near-infrared material, which is constructed with tert-butyl oxygen bridge triphenylamine as donor unit, acenaphthylene [1,2-b] pyrazine-8,9-dicyan, acenaphthylene [1,2-b] quinoline-9,10-dicyan and acenaphthylene [1,2-b] pyrazine [2,3-e] pyrazine-9,10-dicyan as acceptor unit, benzene or anthracene as π bridge.

[0007] The A-π-D type TADF red / near-infrared material provided by the application has a structure shown in Formula I:

[0008] Formula I The A unit and the π bridge are independently selected from any one of Formula II:

[0009] Formula II Preferably, the specific structure of the A-π-D type TADF red / near-infrared material is shown in Formula III, and these compounds are only representative compounds:

[0010] Formula III More preferably, the A unit in the A-π-D type TADF red / near-infrared material is acenaphthylene [1,2-b] pyrazine-8,9-dicyan and acenaphthylene [1,2-b] pyrazine [2,3-e] pyrazine-9,10-dicyan, the donor is tert-butyl oxygen bridge triphenylamine, the benzene ring is the π bridge, the positions of the acceptor and the donor are para, and the molecular structure formulas are named as G-1 and G-2, respectively, as shown in the following formula:

[0011] The preparation method of the A-π-D type TADF red / near-infrared material G-1 or G-2 includes the following steps: 4-(tert-butyl)-2-iodo-1-methoxybenzene is obtained by iodization and methoxy protection of hydroxyl from para-tert-butyl phenol, and tert-butyl oxygen bridge triphenylamine donor unit is obtained by Ullmann reaction, methoxy deprotection and nucleophilic substitution ring closure reaction from 4-bromo-2,6-difluoroaniline; 5-boronic ester-acenaphthene-1,2-dione acceptor intermediate is obtained by electrophilic, oxidation and Miyaura boration from acenaphthene; the donor and the acceptor intermediate are coupled with the π bridge through two Suzuki coupling reactions, and the target product is obtained through Schiff base condensation.

[0012] The application further provides application of the A-π-D type TADF red / near-infrared light-emitting material as a light-emitting layer material of an organic electroluminescent diode, to prepare an organic electroluminescent diode.

[0013] The A-π-D type TADF red / near-infrared light-emitting material device of the application has two structures, wherein the doped device structure is: ITO / PEDOT:PSS (30 nm) / CP (90-99%):G1 or G2 (1-10%) (40 nm) / TmPyPB (50 nm) / LiF (1.5 nm) / Al (120 nm); and the non-doped device structure is: ITO / PEDOT:PSS (30 nm) / G1 or G2 (20 nm) / TmPyPB (40 nm) / LiF (1.2 nm) / Al (120 nm). In the structure, ITO is an indium tin oxide conductive glass, serving as a substrate and an anode; PEDOT:PSS is a hole injection layer; mCP is a light-emitting layer host material; the guest material of the doped device and the light-emitting layer of the non-doped device are both the A-π-D type TADF red / near-infrared light-emitting material constructed by acenaphthopyrazine and t-butyl oxygen bridge triphenylamine according to claim 1; TmPyPB is an electron transport layer; LiF is an electron injection layer, and Al is a cathode.

[0014] The application method one is: the A-π-D type TADF red / near-infrared material G-1 is used as a guest material, and mCP is used as a host material to prepare a doped device by a solution method; when the mass doping ratio of G-1 and G2 is 3.0%, the maximum emission peak of the device is located in a 678 nm red light region, and the external quantum efficiency is as high as 6.13%; under the same conditions, when G-2 is used as a guest material, the maximum emission peak of the device is located in a 624 nm red light region, and the external quantum efficiency is 3.87%.

[0015] The application method two is: when G-1 is used as a light-emitting layer to prepare a non-doped device, the maximum emission peak of the device is located in a 780 nm near-red light region, and the external quantum efficiency is as high as 2.15%; when G-2 is used as a light-emitting layer to prepare a non-doped device, the maximum emission peak of the device is located in a 725 nm near-red light region, and the external quantum efficiency is as high as 3.27%.

[0016] Compared with the prior art, the application has the following advantages: (1) The light-emitting material of the application has a planar nitrogen-oxygen heteroatom structure, strong electron-donating ability, and t-butyl increases the solubility of the material, enriching the existing organic donor material library.

[0017] (2) The light-emitting material of the application has high expandability: by selecting different acceptors and π bridges and modifying the connection sites, the energy level distribution can be broken, the HOMO and LUMO overlap can be reduced, and the band gap (ΔE st ), improve reverse intersystem crossing rate (RISC) K RISC ), regulate the dihedral angle and stacking mode of the donor and acceptor, inhibit the fluorescence quenching caused by pi-pi stacking, and realize efficient red light emission of OLEDs.

[0018] (3) The luminescent material has excellent performance, G-1 is used as a luminescent layer, 780nm emission is obtained in a non-doped device, and the external quantum efficiency is 2.15%.

[0019] (4) The luminescent small molecule material has high thermal stability and excellent carrier transport performance. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The nuclear magnetic hydrogen spectrum of the compound G-1 prepared in the embodiment 1 of the application.

[0021] Figure 2 The nuclear magnetic hydrogen spectrum of the compound G-2 prepared in the embodiment 1 of the application.

[0022] Figure 3 The mass spectrum of the compound G-1 prepared in the embodiment 1 of the application.

[0023] Figure 4 The mass spectrum of the compound G-2 prepared in the embodiment 1 of the application.

[0024] Figure 5 The ultraviolet-visible absorption spectrum of G-1 and G-2 prepared in the embodiment 1 of the application in 10 -5 mol / L concentration toluene solution.

[0025] Figure 6 The photoluminescence spectrum of G-1 and G-2 prepared in the embodiment 1 of the application in 10 -5 mol / L concentration toluene solution.

[0026] Figure 7 The thermogravimetric curve of the solid powder of G-1 and G-2 prepared in the embodiment 1 of the application.

[0027] Figure 8 The fluorescence spectrum (Fl) and phosphorescence spectrum (Ph) of the toluene solution (10 -5 mol / l) of the compound G-1 prepared in the embodiment 1 of the application at 77K temperature.

[0028] Figure 9 The fluorescence spectrum (Fl) and phosphorescence spectrum (Ph) of the toluene solution (10 -5Fluorescence (Fl) and phosphorescence (Ph) spectra of compound G-1 prepared in Example 1 of the present application at 77 K temperature.

[0029] Figure 10 The delay lifetime curve of compound G-1 prepared in Example 1 of the present application doped in PMMA thin film at 1 wt% mass ratio.

[0030] Figure 11 The delay lifetime curve of compound G-2 prepared in Example 1 of the present application doped in mCP thin film at 10 wt% mass ratio.

[0031] Figure 12 The device energy level diagram of doped device prepared by solution method with G-1 and G-2 prepared in Example 1 of the present application as guest and mCP as host.

[0032] Figure 13 The electroluminescence spectrum of doped device prepared by solution method with G-1 and G-2 prepared in Example 1 of the present application as guest and mCP as host.

[0033] Figure 14 The maximum external quantum efficiency vs. luminance curve of doped device prepared by solution method with G-1 and G-2 prepared in Example 1 of the present application as guest and mCP as host.

[0034] Figure 15 The device energy level diagram of non-doped organic electroluminescent device prepared by solution method with G-1 and G-2 prepared in Example 1 of the present application.

[0035] Figure 16 The electroluminescence spectrum of non-doped organic electroluminescent device prepared by solution method with G-1 and G-2 prepared in Example 1 of the present application.

[0036] Figure 17 The maximum external quantum efficiency vs. luminance curve of non-doped organic electroluminescent device prepared by solution method with G-1 and G-2 prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0037] In order to make the application clearer, further describe the application with preferred embodiments and drawings. Those skilled in the art should understand that the specific content described below is illustrative rather than limiting, and the protection scope of the application should not be limited thereto.

[0038] In the present application, the preparation method is a conventional method unless otherwise specified. The raw materials used can be obtained from public commercial channels unless otherwise specified. Example 1

[0039] The synthetic scheme of A-π-D TADF red / near-infrared light-emitting materials G-1 and G-2 based on acenaphtho-pyrazine and tert-butyl oxygen bridge triphenylamine is as follows, wherein all the initial raw materials and reagents are purchased from Bid pharmaceutical reagent company.

[0040] The synthetic route of compounds G-1 and G-2 is as follows

[0041] Synthesis of compound M1 A 1000 mL single-necked flask was added 4-(tert-butyl)-2-iodo-1-methoxybenzene (100 g, 344.67 mmol, 2.5 eq), 4-bromo-2,6-difluoroaniline (28.68 g, 137.87 mmol, 1 eq), activated copper powder (Cu, 35.05 g, 551.48 mmol, 4 eq), potassium carbonate (K2CO3, 95.26 g, 689.35 mmol, 5 eq), 18-crown-6 (9.11 g, 34.47 mmol, 0.1 eq), o-dichlorobenzene (o-DCB, 500.0 mL), and stirred at 180°C for 72 hours under a nitrogen atmosphere. The reaction was stopped, cooled to room temperature, filtered under suction, and the filter cake was washed with 300 mL of DCM. The filtrate was collected, and the organic solvent was removed by distillation under reduced pressure. The residue was poured into 300 mL of water, extracted with DCM three times (50 mL x 3), and the organic phase was combined and washed with water five times (100 mL x 5). The organic phase was separated, dried with magnesium sulfate, filtered to remove the magnesium sulfate, and the DCM was removed under reduced pressure. Column chromatography was performed using PE:DCM=2:1 as the developing agent, vacuum dried at 60°C, and white solid was obtained, 61.27 g, yield: 83.45%. 1 H NMR (400 MHz, CDCl3) δ 7.06 (dd, J = 8.5, 2.3 Hz, 2H), 6.99 (d, J = 8.0 Hz, 2H), 6.92 (d, J = 2.2 Hz, 2H), 6.81 (d, J 8.5 Hz, 2H), 3.56 (s, 6H), 1.20 (s, 18H).

[0042] Synthesis of compound M2 A 200 mL two necked flask was charged with 4-bromo-N,N-bis(5-(tert-butyl)-2- methoxyphenyl)-2,6-difluoroaniline (M1, 5 g, 93.90 mmol, 1 eq), dry dichloromethane solution (DCM, 300.0 mL), cooled to 0 °C, boron tribromide (BBr3, 51.75 g, 206.58 mmol, 2.2 eq) was added slowly and the reaction was stirred at room temperature for 12 h. The reaction was quenched by pouring into 500 mL of ice water and extracted with DCM three times (50 mL x 3) and the organic phase was combined and washed with water three times (200 mL x 3). The organic phase was separated, dried over magnesium sulfate, filtered to remove the magnesium sulfate and the DCM was removed under reduced pressure to give a off-white solid residue which was used as such in the next step without further purification. A 500 mL two necked flask was charged with the off-white solid residue, potassium carbonate (K2CO3, 38.93 g, 281.7 mmol, 3 eq), dry dimethylformamide solution (DMF, 300.0 mL), heated to 120 °C and the reaction was stirred for 12 h. The reaction was stopped and cooled to room temperature, the reaction was poured into 800 mL of water and a large amount of white solid was precipitated, stirred vigorously for 30 min, filtered and the filter cake was washed with distilled water (1500 mL), the filter cake was dried under vacuum at 60 °C to give a white solid 4.24 g, yield: 97.25%. N,N HNMR (400MHz, CDCl3) δ 7.36 (s, 2H), 6.92 (dd, J = 8.5, 1.7 Hz, 2H), 6.85-6.80 (m, 2H), 6.64 (s, 2H), 1.28 (s, 18H). 1 HNMR (400MHz, CDCl3) δ 7.36 (s, 2H), 6.92 (dd, J = 8.5, 1.7 Hz, 2H), 6.85-6.80 (m, 2H), 6.64 (s, 2H), 1.28 (s, 18H). J HNMR (400MHz, CDCl3) δ 7.36 (s, 2H), 6.92 (dd, J = 8.5, 1.7 Hz, 2H), 6.85-6.80 (m, 2H), 6.64 (s, 2H), 1.28 (s, 18H).

[0043] Synthesis of compound M3 A 200 mL two-necked flask was charged with 7-bromo-2,12-di-tert-butylbenzo[5,6][1,4]oxazepino[2,3,4-kl]phenoxazine (M2, 4 g, 86.13 mmol, 1 eq), bis(pinacolato)diboron (B2Pin2, 3.281 g, 12.920 mmol, 1.5 eq), dichloro[1,1'-bis(diphenylphosphino)ferrocene] palladium (Pd(dppf)Cl2, 0.189 g, 0.258 mmol, 0.03 eq), potassium acetate (AcOK, 6.762 g, 68.906 mmol, 8 eq), 1,4-dioxane (Diox, 80.0 mL) and stirred at 110 °C for 12 h under nitrogen atmosphere. After the reaction solution was cooled to room temperature, the solvent 1,4-dioxane was removed by distillation under reduced pressure, the reaction solution was extracted with DCM (50 mL x 3) and water three times, the organic phase was combined and washed with water three times (200 mL x 3). The organic phase was separated, dried over magnesium sulfate, filtered to remove the magnesium sulfate, and DCM was removed under reduced pressure to obtain a white solid residue. Column chromatography was performed using PE:DCM = 1:4 as the developing agent, and the product was purified by column chromatography and dried under vacuum at 60 °C to obtain a white solid 4.21 g, yield: 95.57%. 1 H NMR (400MHz, CDCl3) δ 7.37 (d, J = 1.9 Hz, 2H), 6.91 (s, 4H), 6.81 (d, J = 8.4 Hz,2H), 1.31 (s, 12H), 1.28 (s, 18H).

[0044] Synthesis of compound M4 A 100 mL two-necked flask was charged with 7-(4-bromophenyl)-2,12-di-tert- butylbenzo[5,6][1,4]oxazepino[2,3,4-kl]phenoxazine (M3, 4 g, 7.401 mmol, 1 eq), 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)naphthalene-1,2-dione (M8, 2.736 g, 8.881 mmol, 1.2 eq), tetrakis(triphenylphosphine)palladium(0) (Pd(PPh3)4, 0.428 g, 0.370 mmol, 0.05 eq), potassium carbonate (K2CO3, 2.046 g, 14.801 mmol, 2 eq), tetrahydrofuran (THF, 80.0 mL), and stirred at 85 °C for 12 h. After the reaction solution was cooled to room temperature, the reaction solution was distilled to remove the solvent tetrahydrofuran under reduced pressure, extracted with DCM (50 mL x 3) and water three times, and the organic phase was combined and washed with water three times (200 mL x 3). The organic phase was separated, dried with magnesium sulfate, filtered to remove the magnesium sulfate, and DCM was removed under reduced pressure to obtain a white solid residue. Column chromatography was performed using PE:DCM = 1:1 as the developing agent, and the product was dried at 60 °C under vacuum to obtain a yellowish solid 4.27 g, yield: 96.99%. 1 H NMR (400 MHz, CDCl3) δ 8.44 (d, J = 8.6 Hz, 1H), 8.20 (d, J = 7.3Hz, 1H), 8.15 (d, J = 6.9 Hz, 1H), 7.85 (t, J = 7.5 Hz, 2H), 7.72 (d, J = 8.4Hz, 2H), 7.66 (d, J = 8.3 Hz, 2H), 7.44 (d, J = 2.1 Hz, 2H), 6.99 – 6.94 (m,2H), 6.89 (d, J = 8.4 Hz, 2H), 6.85 (s, 2H), 1.31 (s, 18H)。

[0045] Synthesis of compound G-1 In a 100 mL two-necked flask, ADO-oDTPA (M4, 2 g, 3.116 mmol, 1 eq), diaminomaleonitrile (DAMN, 0.337 g, 3.116 mmol, 1 eq), acetic acid 60 mL, the temperature was raised to 120 °C, and stirred under reflux for 24 h. After the reaction was completed, it was cooled to room temperature, poured into water, and filtered under reduced pressure and washed with a large amount of water. The residue was dried and separated and purified on a silica gel column with dichloromethane: petroleum ether = 1:1 (volume ratio) as eluent. The product was refluxed in ethanol, filtered and dried. Finally, 1.87 g of purple red solid was obtained with a yield of 84.06%. The compound was further purified by sublimation before being used in device. 1 H NMR (400 MHz, CDCl3) δ 8.50 (dd, J = 14.8, 7.2 Hz, 2H), 8.38 (d, J = 8.4Hz, 1H), 7.90 (d, J = 7.5 Hz, 2H), 7.63 (d, J = 7.9 Hz, 4H), 7.37 (d, J = 2.1Hz, 2H), 6.90 (dd, J = 8.4, 2.1 Hz, 2H), 6.81 (d, J = 8.4 Hz, 2H), 6.76 (s,2H), 1.25 (s, 18H).

[0046] Synthesis of compound G-2 The synthesis of compound G-2 was consistent with the synthesis conditions of compound intermediate G-1, using 4,5-diaminophthalonitrile (DAPN, 0.493 g, 3.116 mmol, 1 eq) instead of diaminomaleonitrile, and other conditions were consistent. Red solid 1.99 g was obtained by column chromatography (eluent ratio dichloromethane: petroleum ether = 5:4) (yield 83.60%). 1 H NMR (400MHz, CDCl3) δ 8.65 (s, 2H), 8.57 (dd, J = 11.3, 7.1 Hz, 2H), 8.41 (d, J = 8.4Hz, 1H), 7.95 (d, J = 7.3 Hz, 2H), 7.70 (d, J = 1.3 Hz, 4H), 7.44 (d, J= 8.4, 2.1 Hz, 2H), 6.88 (d, J = 8.4, 2.1 Hz, 2H), 6.88 (d, J = 8.4 Hz, 2H), 6.84 (s,2H), 1.32 (s, 18H). Example 2

[0047] The compounds G-1 and G-2 of Example 1 were dissolved in deuterated reagent respectively, and its nuclear magnetic resonance hydrogen spectrum was tested by 400 Mhz nuclear magnetic resonance spectrometer, as shown in Figures 1-2 . Example 3

[0048] The compounds G-1 and G-2 of Example 1 were dissolved in acetonitrile reagent respectively, and it was tested by SCIEX TripleTOF6600 nanoLCMS type liquid chromatography tandem high resolution mass spectrometer, and its mass spectrum is as shown in Figures 3-4 , the theoretical molecular weight is consistent with the molecular weight obtained by mass spectrometer test, obviously, the molecular weight of the compound is accurate. Example 4

[0049] The compounds G-1 and G-2 of Example 1 were dissolved in toluene solution (10 -5 M) respectively, and the ultraviolet-visible light absorption spectrum of the two compounds at room temperature was measured. As can be seen from Figure 5 , the compounds G-1 and G-2 show two main absorption bands, the strong absorption band in the range of 300 nm to 400 nm is derived from the intramolecular π-π * transition, and the absorption peak at 440-550 nm is the CT action peak caused by the transition between the electron-donating unit and the electron-withdrawing unit. Example 5

[0050] The compounds G-1 and G-2 of Example 1 were dissolved in toluene solution (10 -5 M) respectively, and the photoluminescence spectrum at room temperature was measured. As can be seen from Figure 6 , the compounds G-1 and G-2 show strong emission peaks at 710 nm and 650 nm respectively, which are red and near-infrared emission, and the half peak width is 160 nm and 147 nm. Example 6

[0051] The compounds G-1 and G-2 prepared in Example 1 were tested for thermal stability. Under nitrogen atmosphere, the thermal gravimetric test was carried out at a heating rate of 20 ℃ / min from room temperature to 700 ℃. As can be seen from Figure 7As shown, the temperature at which 5% weight loss of compounds G-1 and G-2 is 481.9 and 477.9 ℃, respectively, indicating that the materials have good thermal stability, which lays a foundation for subsequent solution processing of the materials as light-emitting layers and preparation of full-vapor devices. Example 7

[0052] The fluorescence spectrum (Fl) and phosphorescence spectrum (Ph) of compounds G-1 and G-2 prepared in Example 1 were tested at 77K. Both the low-temperature fluorescence and low-temperature phosphorescence spectra showed a wide and non-fine-structured peak shape, which also meant that it was generated by intramolecular charge transfer. According to the peak position of the low-temperature fluorescence spectrum and phosphorescence spectrum and the formula E = 1240 / λ, the S1 energy level of compounds G-1 and G-2 was estimated to be 2.27 and 2.13 eV, respectively, and the T1 energy level was 2.20 and 2.02 eV, respectively, Δ E ST 0.07 and 0.11 eV, respectively, as shown in Figure 8 and Figure 9 Example 8

[0053] The delayed lifetime of compounds G-1 and G-2 prepared in Example 1 in PMMA films doped at 1 wt% mass ratio was tested under nitrogen atmosphere by FlS1000, and the lifetime of G-1, G-2, and doped films was 1.81 and 8.22 μs, respectively, by fitting, as shown in Figure 10 and 11 Example 9

[0054] Application of compounds G-1 and G-2 in Example 1 in organic electroluminescent devices. With the compounds as guest materials of light-emitting layers, organic electroluminescent diodes with the structure of ITO / PEDOT:PSS (30 nm) / mCP (90-99%): G1 or G2 (1-10%) (40 nm) / TmPyPB (50 nm) / LiF (1.5 nm) / Al (120 nm) were prepared. Among them, PEDOT:PSS is a hole injection layer, mCP is a light-emitting layer host material, TmPyPB is an electron transport layer, LiF is an electron injection layer, and Al is a cathode, as shown in Figure 12 Example 10

[0055] The electroluminescence spectrum of compounds G-1 and G-2 in Example 1 in organic electroluminescent devices is shown in Figure 13 , and the maximum emission peak of the doped devices is at 678 and 624 nm, respectively, at 1-10 wt% mass doping. Example 11 ​​​

[0056] The external quantum-efficiency curves of the compounds G-1 and G-2 in Example 1 in solution-processed non-doped organic electroluminescent devices are shown in FIG. 2. The maximum external quantum efficiencies of the doped devices are 7.24% and 3.87% at 1-10 wt% doping concentration. Figure 14 Example 12

[0057] In view of the excellent photoluminescence performance of the compounds G-1 and G-2 in Example 1, in order to further study their performance in electroluminescence, non-doped OLEDs were prepared by solution method, and the structure was ITO / PEDOT: PSS (30 nm) / EML (20 nm) / TmPyPB (40 nm) / LiF (1.2 nm) / Al (120 nm). Among them, the pure thin film of the compounds G-1 and G-2 was used as the light-emitting layer (EML), as shown in FIG. 3. Figure 15 Example 13

[0058] The electroluminescence spectra of the compounds G-1 and G-2 in Example 1 in solution-processed non-doped organic electroluminescent devices are shown in FIG. 4. When the compounds G-1 and G-2 were used as the light-emitting layer, the electroluminescent devices showed red light emission, and the maximum emission peaks of the non-doped devices were at 780 and 725 nm, respectively. Figure 16 Example 14

[0059] The external quantum-efficiency curves of the compounds G-1 and G-2 in Example 1 in solution-processed non-doped organic electroluminescent devices are shown in FIG. 5. When the compounds G-1 and G-2 were used as the light-emitting layer, the maximum external quantum efficiencies of the non-doped devices were 2.15% and 3.27%, respectively. Figure 17

[0060] Although the present application has been described in connection with the preferred embodiments thereof, it will be understood that the application is not limited to the embodiments, and it is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains.​​​​

Claims

1. A type of A-π-D type TADF red / near-infrared luminescent material, characterized in that: The chemical structure of the luminescent material is shown in Formula-1. ， Formula-1 Wherein, the A unit and the π bridge are independently selected from any one of the following molecular structures: 。 2. The A-π-D type TADF red / near-infrared luminescent material according to claim 1, characterized in that: The molecular structural formula of the luminescent material is any one of the following: 。 3. The A-π-D type TADF red / near-infrared luminescent material according to claim 1, characterized in that The molecular structural formula of the luminescent material is any one of the following: 。 4. Use of the A-π-D type TADF red / near-infrared luminescent material according to claim 1, characterized in that: The luminescent material is used for preparing an organic electroluminescent diode.

5. Use of the A-π-D type TADF red / near-infrared luminescent material according to claim 4, characterized in that: The luminescent material is used as a guest material to be doped with a host material to form a luminescent layer of an organic electroluminescent diode, or is directly used as a luminescent layer of an organic electroluminescent diode.

6. Use of the A-π-D type TADF red / near-infrared luminescent material according to claim 5, characterized in that: The main material is mCP, and the mass ratio of doping is 1-10%.

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