A class of MR-TADF blue light-emitting materials and their application in near-infrared excimer OLEDs

Abstract

This invention discloses a class of MR-TADF blue luminescent materials and their application in near-infrared excimer organic light-emitting devices (OLEDs). A class of blue luminescent materials with MR-TADF properties was obtained through the Suzuki coupling reaction of 1-quinolinoacridididine dione units and 7-dioxaborane-naphthyl anthracene units. Using these materials as the acceptor component of the excimer and m-MTDATA blue fluorescent material as the donor component, the active luminescent layer was prepared by mixing the two materials in different proportions via a solution method, achieving highly efficient near-infrared excimer luminescence. The results show that the solution-processed OLEDs exhibit high near-infrared luminescence efficiency, with the electroluminescence peak located in the 706–726 nm range and the corresponding maximum external quantum efficiency (EQE) in the 0.35–0.17% region, demonstrating promising application prospects.

Description

Technical Field

[0001] This invention belongs to the fields of light emission, display lighting and biomedical technology. Specifically, it relates to the coupling of a dual MR unit containing a nitrogen carbonyl core with multiple resonance (MR) characteristics and a boron oxygen core with MR characteristics, thereby obtaining an organic multiple resonance thermally activated delayed fluorescence (MR-TADF) blue light material, which is then used as an acceptor component of the exciton complex to prepare near-infrared exciton complex organic electroluminescent devices (OLEDs). Background Technology

[0002] Organic light-emitting diodes (OLEDs) have received widespread attention since their advent in the 20th century, and their unique advantages such as thinness, transparency, and flexibility have led to their application in lighting, screen displays, and other fields. Among them, near-infrared organic light-emitting diodes (NIR-OLEDs) have broad application prospects in light emission, display lighting, and biomedicine. The proposal of thermally activated delayed fluorescence (TADF) materials in 2012 greatly accelerated the development of OLEDs (Nature, 2012, 492, 234). However, TADF materials still have problems such as high turn-on voltage, large efficiency roll-off at high brightness, and complex molecular synthesis. The exciton complex consists of two parts: a donor and an acceptor. Its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are located on the donor and acceptor molecules, respectively, resulting in a small ΔEST of the exciton complex. This allows for 100% exciton utilization through reverse gap crossing (RISC). Compared to electroluminescent devices constructed from pure organic TADF emissive layer materials, electroluminescent devices based on excimer composite emissive active layers have advantages such as lower turn-on voltage and reduced efficiency roll-off at high brightness. In particular, excimer composites only require blending two simple donor and acceptor materials to obtain novel materials with a relative redshift in emission. In 2016, Monkman first obtained a near-infrared excimer composite by blending OZDBPHZ and m-MTDATA, demonstrating the enormous potential of deep red / near-infrared excimer composite emitters in OLED applications (Angew. Chem. Int. Ed. 2016, 55, 5739-5744). In 2020, Liao Liangsheng's research group obtained a near-infrared excimer composite with 730 nm emission by blending a 510 nm green light material with TCTA, with an efficiency of only 0.09%. In 2021, based on this material, they derived a near-infrared excimer composite with 750 nm emission by blending it with PO-01, achieving an efficiency of 0.23%. Summary of the Invention

[0003] There are few reports on near-infrared excimer complexes, and their luminescence efficiency and chemical structure diversity lag far behind those of single-molecule near-infrared TADF materials.

[0004] This invention designs a class of organic blue light-emitting materials with both MR and TADF characteristics and large steric hindrance by coupling two MR units, namely a nitrogen carbonyl core with multiple resonance (MR) characteristics and a boron-oxygen core with MR characteristics. 1) High-efficiency narrow-spectral-band emission is achieved by utilizing the synergistic strategy of MR effect and TADF excited state; 2) Large steric hindrance caused by the large torsion of the two units and the steric hindrance of the tert-butyl group are used to suppress aggregation emission; 3) The material is selected as the acceptor component of the exciton complex and combined with the classic blue light-emitting material 4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA) as the donor component, resulting in near-infrared exciton complex OLEDs with strong resistance to heavy doping and high luminous efficiency, which is of great significance for enriching the near-infrared exciton complex system.

[0005] One objective of this invention is to provide a class of MR-TADF blue light-emitting materials. These materials are obtained through a Suzuki coupling reaction between a 1-quinolinoacrididine dione unit and a 7-dioxaborane anthracene unit, resulting in a class of blue light-emitting materials exhibiting MR-TADF properties. This MR-TADF blue light-emitting material has the structural characteristics shown in formula (1).

[0006] Equation (1).

[0007] Wherein: the R group is hydrogen or tert-butyl.

[0008] Specifically, the representative compound structures of the MR-TADF blue light-emitting material provided by this invention are as follows: .

[0009] Another object of the present invention is to provide the application of this type of organic MR-TADF blue light emitting material in the fabrication of organic electroluminescent devices (OLEDs).

[0010] The electroluminescent device has the following structure from bottom to top: a substrate, an anode electrode, a hole injection layer, an active light-emitting layer, an electron transport layer, an electron injection layer, and a cathode electrode. The active light-emitting layer is prepared by mixing 4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA) as the donor component and the MR-TADF blue light-emitting material provided by this invention as the acceptor component, using a solution method in different proportions; or, the active light-emitting layer is prepared by mixing the MR-TADF blue light-emitting material provided by this invention as the acceptor component and the classic blue light-emitting material m-MTDATA as the donor component, using a solution method in different proportions.

[0011] Among them, indium tin oxide (ITO) glass is used as the substrate and anode material, PEDOT:PSS is used as the hole injection layer material, TmPyPB is used as the electron transport layer material, LiF is used as the electron injection layer material, and aluminum (Al) is used as the cathode material.

[0012] In an exemplary embodiment of the present invention, a near-infrared excimer composite organic electroluminescent device is provided, the structure of which is: ITO (110 nm) / PEDOT:PSS (40 nm) / Exciplex (40 nm) / TmPyPb (55 nm) / LiF (1 nm) / Al (150 nm). Wherein, the Exciplex is a light-emitting layer composed of LY-JP and 4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA) in different proportions. This invention uses it as the acceptor component of the near-infrared excimer complex luminescent layer material and applies it to solution-based organic light-emitting diodes to improve the purity of the emitted color, luminous efficiency, and lifespan of the device.

[0013] Preferably, the present invention provides an MR-TADF blue light-emitting material as a light-emitting layer acceptor component material for use in the fabrication of a near-infrared excimer composite OLED device, the structural formula of which is LY-JP: .

[0014] Preferably, the doping amount of LY-JP in the excitocomplex prepared by blending the organic MR-TADF blue light emitting material compound LY-JP with the donor material m-MTDATA is 10-80%, more preferably 10-50%, even more preferably 10-40%, and most preferably 20%.

[0015] In an exemplary embodiment of the present invention, excitocomposite OLEDs prepared by blending the organic MR-TADF blue light emitting material compound LY-JP with the donor material m-MTDATA in a mass blending ratio of 2:8 were obtained, exhibiting near-infrared emission with an electroluminescence wavelength of 709 nm and a maximum external quantum efficiency of 0.35%.

[0016] Compared with the prior art, the present invention has at least one of the following beneficial effects: (1) The organic MR-TADF blue light emitting material of the present invention has a simple molecular structure and many modifiable sites, which can enrich the library of organic MR-TADF blue light emitting materials.

[0017] (2) The organic MR-TADF blue light emitting material of the present invention has dual characteristics of MR effect and TADF excited state. As a near-infrared excimer complex acceptor material, it has high luminous efficiency and creates conditions for high-efficiency excimer complex near-infrared OLEDs.

[0018] (3) The organic MR-TADF blue light emitting material of the present invention has high thermal stability, good film formation, and excellent carrier transport performance. Attached Figure Description

[0019] Figure 1 Thermogravimetric curve of compound LY-JP obtained in Example 1 of this invention in a thin film.

[0020] Figure 2 This is the ultraviolet-visible absorption spectrum of the compound LY-JP obtained in Example 1 of the present invention in a thin film.

[0021] Figure 3 This is the photoluminescence spectrum of the compound LY-JP obtained in Example 1 of the present invention in a thin film.

[0022] Figure 4 The image shows the delayed lifetime of the compound LY-JP prepared in Example 1 of this invention in a 2% doped CBP film measured under a nitrogen atmosphere.

[0023] Figure 5 The graph shows the instantaneous lifetime of the active layer system prepared in Example 1 of this invention, which is a blend of compound LY-JP and m-MTDATA in a mass ratio of 2:8, in a thin film.

[0024] Figure 6 The graph shows the delayed lifetime of the active layer system prepared in Example 1 of this invention, which is a blend of compound LY-JP and m-MTDATA in a mass ratio of 2:8, in a thin film.

[0025] Figure 7 This is a device structure diagram of an electroluminescent device using the compound LY-JP and m-MTDATA obtained in Example 1 of the present invention as the active light-emitting layer of the exciton complex.

[0026] Figure 8 The electroluminescence spectra of the compound LY-JP and m-MTDATA prepared in Example 1 of this invention at different mass blending ratios are shown.

[0027] Figure 9 The graph shows the external quantum efficiency curves of the compound LY-JP and m-MTDATA prepared in Example 1 of this invention at different mass blending ratios. Detailed Implementation

[0028] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. Those skilled in the art should understand that the specific details described below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0029] In this invention, the preparation methods are all conventional unless otherwise specified. The raw materials used are all available from publicly available commercial sources unless otherwise specified. Example 1

[0030] Preparation of representative compound LY-JP The specific synthetic route of the compound LY-JP of this invention is as follows:

[0031] Synthetic route of compound LY-JP Synthesis of compound M1 Under a nitrogen atmosphere, 2,5-dibromo-1,3-difluorobenzene (30 g, 110.34 mmol), 4-tert-butylphenol (33.15 g, 220.68 mmol), potassium carbonate (K₂CO₃, 45.75 g, 331.02 mmol), and dry N-methylpyrrolidone (NMP, 100.0 mL) were added to a 250 mL single-necked flask. The mixture was heated to 200 °C and stirred overnight. The reaction was stopped, cooled to room temperature, and the reaction mixture was poured into 100 mL of distilled water and filtered. The filter cake was washed with 20 mL of methanol solution and dried under vacuum at 60 °C to give a white solid M1: 55.12 g, yield: 93.84%. 1H NMR (400 MHz, CDCl3) δ 8.03 (dd, J =3.5, 1.7 Hz, 4H), 7.95 (s, 2H), 7.77 (d, J = 1.7 Hz, 2H), 7.50 (dd, J = 8.6,1.9 Hz, 2H), 7.40 (d, J = 8.5 Hz, 2H), 1.44 (d, J = 4.7 Hz, 36H). MALDI-TOFMS (mass m / z): 532.04 (100.0%), 530.05 (51.4%), 534.04 (48.6%), 533.05(28.6%), 531.05 (14.7%), 535.04 (13.7%), 534.05 (4.3%), 532.05 (2.2%), 536.05 (2.1%).

[0032] Synthesis of compound M2 Under a nitrogen atmosphere, M1 (30 g, 56.36 mmol) and toluene (Tol, 200 mL) were added to a 500 mL two-necked flask. After pre-cooling at low temperature for 30 min, n-BuLi (2.4 mol / L, 72.26 mmol, 30 mL) was slowly added dropwise. The mixture was reacted at low temperature for 1 h and then moved to room temperature for 2 h. After pre-cooling at low temperature for 30 min, boron tribromide (BBr3, 90.17 mmol, 8.6 mL) was slowly added dropwise. The mixture was reacted at low temperature for 1 h and then moved to room temperature for 3 h. After pre-cooling at low temperature for 10 min, N,N-diisopropylethylamine (DIPEA, 140.89 mmol, 25 mL) was slowly added dropwise. The mixture was reacted at low temperature for 10 min and then moved to room temperature for 2 h. Finally, the mixture was heated to 120 °C and refluxed for 24 h. The reaction was stopped, cooled to room temperature, poured into 300 mL of methanol, filtered, and dried under vacuum at 60 °C to give a white solid M2: 16.5 g, yield 63.48%. 1H NMR (400 MHz, CDCl3) δ 8.72 (d, J = 2.5 Hz, 2H), 8.72 (d, J = 2.5Hz, 2H), 7.79 (dd, J = 8.8, 2.5 Hz, 2H), 7.79 (dd, J = 8.8, 2.5 Hz, 2H), 7.47(d, J = 8.8 Hz, 2H), 7.47 (d, J = 8.8 Hz, 2H), 7.36 (s, 2H), 7.36 (s, 2H),7.26 (s, 1H), 1.56 (s, 2H), 1.48 (s, 18H), 1.48 (s, 18H), 0.07 (s, 3H).MALDI-TOF MS (mass m / z): 460.12 (100.0%), 462.12 (97.3%), 461.12 (52.3%), 463.12 (27.4%), 459.12 (24.8%), 462.13 (11.3%), 460.13 (7.1%), 464.13 (3.9%), 463.13 (1.8%), 461.13 (1.4%).

[0033] Synthesis of compound M3 Under a nitrogen atmosphere, M2 (10 g, 21.68 mmol), 4,4,4',4',5,5,5',5'-octamethyl-2,2'-bi(1,3,2-dioxaborane) (6.61 g, 26.02 mmol), potassium acetate (ACOK, 10.64 g, 108.41 mmol), [1,1′-bis(diphenylphosphine)ferrocene]palladium(II) dichloride (Pd(dppf)Cl2, 0.476 g, 0.65 mmol), and dried dioxane (Diox, 120 mL) were added to a 250 mL single-necked flask. The mixture was heated to 110 °C and refluxed for 24 h. The reaction was stopped, cooled to room temperature, and extracted three times with DCM (20 mL × 3). The organic phases were combined and washed three times with water (30 mL × 3). The organic phase was separated, dried with magnesium sulfate, filtered to remove magnesium sulfate, and DCM was removed under reduced pressure. The purified phase was then separated by column chromatography using PE:DCM = 3:1 as the developing solvent, and dried under vacuum at 60°C. A white solid M3 of 10.5 g was obtained, with a yield of 95.28%. 1H NMR (400 MHz, CDCl3) δ 8.75(d, J = 2.4 Hz, 2H), 7.79 (d, J = 2.5 Hz, 1H), 7.77 (d, J = 2.5 Hz, 1H), 7.65(s, 2H), 7.50 (s, 1H), 7.48 (s, 1H), 1.48 (s, 18H), 1.40 (s, 12H). MALDI-TOFMS (mass m / z): 508.30 (100.0%), 507.30 (42.4%), 509.30 (30.4%), 510.30(5.7%), 506.30 (5.3%), 509.31 (2.6%), 507.31 (1.9%).

[0034] Synthesis of compound M4 Under a nitrogen atmosphere, methyl 2-methylbenzoate (10 g, 38.2 mmol), 2-bromoaniline (2.6 g, 15.3 mmol), potassium carbonate (5.3 g, 38.2 mmol), copper powder (244 mg, 3.82 mmol), and cuprous iodide (291.4 mg, 1.53 mmol) were added to a 250 mL single-necked flask. Dry o-dichlorobenzene was used as the reaction solvent. The mixture was heated to 180 °C and reacted for 2 days. After cooling to room temperature, O-DCB was removed by vacuum distillation. The mixture was extracted with dichloromethane (3 × 30 mL). The collected organic phase was washed with water, dried, and the solvent was removed by vacuum distillation. The residue was separated by column chromatography using petroleum ether / dichloromethane (1 / 1) as the eluent to obtain a white solid M4: 3.36 g, yield 50%. 1H NMR (400 MHz, CDCl3) δ 7.69-7.63 (m, 1H), 7.60 (d, J =1.6 Hz, 2H), 7.42-7.30 (m, 2H), 7.25-7.19 (m, 1H), 7.17-7.11 (m, 1H), 7.07(ddd, J = 8.4, 5.7, 1.8 Hz, 2H), 7.02-6.96 (m, 2H), 6.91 (d, J = 7.9 Hz, 1H), 3.41 (d, J = 7.1 Hz, 6H). MALDI-MS (m / z): calcd. 440.29 found. 439.04. MALDI-TOF MS (mass m / z): 439.04 (100.0%), 441.04 (97.4%), 440.05 (24.2%), 442.04 (23.7%), 441.05 (3.6%), 443.05 (2.7%).

[0035] Synthesis of compound M5 Under a nitrogen atmosphere, M4 (3.15 g, 7.15 mmol), sodium hydroxide (5.7 g, 143.08 mmol), 50 mL of ethanol, and 50 mL of distilled water were added to a 250 mL single-necked flask. The mixture was heated to 100 °C and reacted for 48 h. After stopping the reaction and cooling to room temperature, the ethanol was removed by vacuum distillation. Then, hydrochloric acid was added to precipitate the solid, which was then filtered to obtain a white solid M5: 2.9 g, yield: 95%. No further purification was required, and the mixture was directly fed to the next step.

[0036] Synthesis of compound M6 First, M5 (500 mg, 1.21 mmol), oxalyl chloride (369.36 mg, 2.91 mmol), and 30 mL of dry dichloromethane were placed in a 50 mL double-necked flask. Two drops of dry DMF were added as a catalyst, and the mixture was refluxed at 55 °C for 0.5 h. Then, tin tetrachloride (0.34 mL, 2.91 mmol) was injected into the reaction system, and the mixture was refluxed for 3 h. After cooling to room temperature, the mixture was extracted (3 × 20 mL), washed with water, dried, and the residue was collected. Column chromatography using petroleum ether / dichloromethane (2 / 1) as the eluent yielded a yellow solid M6: 91 mg, with a yield of 20%. 1H NMR (400 MHz, CDCl3) δ 8.69 (dd, J = 7.6, 1.6 Hz, 1H), 8.61 (dd, J = 7.7, 1.6 Hz, 1H), 8.48 (dd, J = 7.8, 1.5 Hz, 1H), 8.38 (dd, J = 7.9,1.5 Hz, 1H), 7.96 (dd, J = 7.8, 1.5 Hz, 1H), 7.68-7.59 (m, 2H), 7.46 (dd, J =8.7, 1.6 Hz, 1H), 7.42 (d, J = 7.8 Hz, 2H). MALDI-MS (m / z): calcd. 376.21found. 376.3. MALDI-TOF MS (mass m / z): 374.99 (100.0%), 376.99 (97.8%), 375.99 (22.1%), 377.99 (21.2%), 378.99 (2.6%), 377.00 (2.3%).

[0037] Synthesis of compound LY-JP Under a nitrogen atmosphere, M6 (2 g, 5.3 mmol), M3 (3.24 g, 6.4 mmol), tetrakis(triphenylphosphine palladium) (122.9 mg, 0.02 mmol), potassium carbonate (2.9 g, 2.13 mmol), and 30 mL of tetrahydrofuran were added sequentially to a 200 mL single-necked flask. The mixture was heated to 80 °C and reacted for 24 h. The reaction was stopped, cooled to room temperature, and THF was removed by vacuum distillation. The mixture was extracted with dichloromethane (3 × 30 mL). The collected organic phase was washed with water, dried, and the solvent was removed by vacuum distillation. The residue was separated by column chromatography using petroleum ether / dichloromethane (2 / 1) as the eluent to obtain a yellow solid LY-JP: 1.61 g, yield: 45%. 1H NMR (400 MHz, DMSO) δ 8.62 (dd, J = 7.5, 3.1 Hz, 2H), 8.54 (s, 2H), 8.44 (d, J = 7.7 Hz, 1H), 8.05 (d, J = 7.4 Hz, 1H), 7.77 (dd, J = 16.3, 8.4 Hz, 5H), 7.58 (d, J =29.3 Hz, 2H), 7.34 (d, J = 8.4 Hz, 2H), 7.10 (t, J = 7.7 Hz, 1H), 6.82 (t, J= 7.5 Hz, 1H), 6.50 (s, 1H), 1.42 (s, 18H). MALDI-TOF MS (mass m / z): 677.27 (100.0%), 678.28 (53.5%), 676.28 (24.8%), 679.28 (13.3%), 677.28 (12.5%), 680.28 (2.4%). Example 2

[0038] The compound LY-JP from Example 1 was heated in the range of 30–700 °C under N2 protection at a rate of 20 °C / min, and its thermogravimetric curve was measured. Figure 1 It can be seen that the decomposition temperature of compound LY-JP by 5% is 392.0 ℃. Example 3

[0039] Compound LY-JP from Example 1 was dissolved in toluene to prepare a 10 mg / mL toluene solution. This toluene solution was then spin-coated onto an ITO surface at 1000 r / min, and the UV-Vis absorption spectrum was measured at room temperature. Figure 2It can be seen that the absorption peaks before 400 nm are attributed to the n-π* transition absorption of molecules, the absorption peaks around 400 nm are mainly attributed to the π-π* transition absorption of molecules, and the absorption peaks around 450 nm are characteristic absorption peaks caused by MR. Example 4

[0040] The compound LY-JP from Example 1 was dissolved in toluene to prepare a 10 mg / mL toluene solution. This toluene solution was then spin-coated onto an ITO surface at 1000 r / min, and the photoluminescence spectrum was measured at room temperature. Figure 3 It can be seen that the emission peak of LY-JP is located at 465 nm, which is a blue light emitting material; its half-width is less than 70 nm, which is 30 nm, which is a typical characteristic of MR-TADF light emitting materials. Example 5

[0041] The fluorescence lifetime of compound LY-JP from Example 1 in a 2% doped CBP film was tested under a nitrogen atmosphere. Figure 4 As shown, the delayed lifetime of compound LY-JP was found to be 40.15 μs after fitting, further indicating that the compound is an MR-TADF material. Example 6

[0042] Using compound LY-JP from Example 1 as the acceptor component and the classic m-MTDATA as the donor component, a thin film was prepared by spin-coating LY-JP and m-MTDATA at a mass ratio of 2:8 onto an ITO surface and its transient lifetime was tested using an FLIS1000. Figure 5 It can be seen that the instantaneous lifetime is 4.84 ns after fitting, indicating that the active layer of the LY-JP:m-MTDATA (2:8) blend has TADF characteristics. Example 7

[0043] Using compound LY-JP from Example 1 as the acceptor component and the classic m-MTDATA as the donor component, a thin film was prepared by spin-coating LY-JP and m-MTDATA at a mass ratio of 2:8 onto an ITO surface and its transient lifetime was tested using an FLIS1000. Figure 6 It can be seen that the delayed lifetime is 1.1 μs after fitting, indicating that the active layer of the LY-JP:m-MTDATA (2:8) blend has TADF characteristics. Example 8

[0044] Application of compound LY-JP in organic electroluminescent devices in Example 1. Compound LY-JP was used as the acceptor component, and classic m-MTDATA as the donor component. A blend of LY-JP and m-MTDATA at a mass ratio of 2:8 was used as the emitting layer material to prepare a near-infrared device with the structure: ITO (110 nm) / PEDOT:PSS (40 nm) / Exciplex (40 nm) / TmPyPb (55 nm) / LiF (1 nm) / Al (150 nm). Figure 7 As shown.

[0045] Among them, indium tin oxide (ITO) glass is the anode material, PEDOT:PSS is the hole injection layer material, Exciplex is the light-emitting layer of LY-JP and m-MTDATA mixture, TmPyPB is the electron transport layer material, LiF is the electron injection layer material, and aluminum (Al) is the cathode material. Example 9

[0046] The compound LY-JP from Example 1 was used as the acceptor component of the active layer, and the purchased compound m-MTDATA was used as the donor component. The LY-JP / m-MTDATA mass ratios were 1:9, 2:8, 4:6, 5:5, 6:4, and 8:2, respectively, to form the active luminescent layer of the exciton complex. The obtained near-infrared electroluminescence spectra of the exciton complex are shown below. Figure 8 As shown. By Figure 8 It can be seen that the electroluminescence wavelengths of different doping ratios are 701 nm, 709 nm, 712 nm, 718 nm, 720 nm and 720 nm, respectively, indicating that the excitocomplexes formed by LY-JP and m-MTDATA under different ratios all achieve near-infrared emission. Example 10

[0047] The compound LY-JP from Example 1 was used as the acceptor component of the active layer, and the purchased compound m-MTDATA was used as the donor component. The LY-JP / m-MTDATA mass ratios were 1:9, 2:8, 4:6, 5:5, 6:4, and 8:2, respectively, to form the active luminescent layer of the exciton complex. The near-infrared external quantum efficiency curves of the obtained exciton complex are shown below. Figure 9 As shown. By Figure 9 It can be seen that the external quantum efficiencies of different doping ratios are 0.27%, 0.35%, 0.28%, 0.23%, 0.19%, and 0.17%, respectively. The electroluminescence performance parameters of the devices with different doping ratios in this embodiment are recorded in Table 1.

[0048] Table 1 Electroluminescence performance parameters of devices with different doping ratios in the embodiments of the present invention .

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Use of a class of MR-TADF blue light-emitting materials in the preparation of near-infrared exciplex light-emitting devices, characterized in that, The chemical structure of the MR-TADF blue light-emitting material is shown in the following formula: ， The MR-TADF blue light-emitting material is used to prepare the active light-emitting layer of a near-infrared excitocomplex light-emitting device; the active light-emitting layer is an excitocomplex film prepared by mixing the MR-TADF blue light-emitting material as the excitocomplex acceptor component with a donor component; the donor component is 4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine.

2. The application according to claim 1, characterized in that, In the excitocomposite, the doping amount of MR-TADF blue light material is 10~80%.

3. The application according to claim 2, characterized in that, In the excitocomposite, the doping amount of MR-TADF blue light material is 10~50%.

4. The application according to claim 1, characterized in that, The structure of the near-infrared excimer composite light-emitting device, from bottom to top, includes: a substrate, an anode electrode, a hole injection layer, an active light-emitting layer, an electron transport layer, an electron injection layer, and a cathode electrode; the substrate and anode materials are indium tin oxide glass, the hole injection layer material is PEDOT:PSS, the electron transport layer material is TmPyPB, the electron injection layer material is LiF, and the cathode material is aluminum.

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